High tumor mutation burden fails to predict immune checkpoint blockade response across all cancer types

BACKGROUND

High tumor mutation burden (TMB-H) has been proposed as a predictive biomarker for response to immune checkpoint blockade (ICB), largely due to the potential for tumor mutations to generate immunogenic neoantigens. Despite recent pan-cancer approval of ICB treatment for any TMB-H tumor, as assessed by the targeted FoundationOne CDx assay in nine tumor types, the utility of this biomarker has not been fully demonstrated across all cancers.

PATIENTS AND METHODS

Data from over 10 000 patient tumors included in The Cancer Genome Atlas were used to compare approaches to determine TMB and identify the correlation between predicted neoantigen load and CD8 T cells. Association of TMB with ICB treatment outcomes was analyzed by both objective response rates (ORRs, N = 1551) and overall survival (OS, N = 1936).

RESULTS

In cancer types where CD8 T-cell levels positively correlated with neoantigen load, such as melanoma, lung, and bladder cancers, TMB-H tumors exhibited a 39.8% ORR to ICB [95% confidence interval (CI) 34.9-44.8], which was significantly higher than that observed in low TMB (TMB-L) tumors [odds ratio (OR) = 4.1, 95% CI 2.9-5.8, P < 2 × 10^-16]. In cancer types that showed no relationship between CD8 T-cell levels and neoantigen load, such as breast cancer, prostate cancer, and glioma, TMB-H tumors failed to achieve a 20% ORR (ORR = 15.3%, 95% CI 9.2-23.4, P = 0.95), and exhibited a significantly lower ORR relative to TMB-L tumors (OR = 0.46, 95% CI 0.24-0.88, P = 0.02). Bulk ORRs were not significantly different between the two categories of tumors (P = 0.10) for patient cohorts assessed. Equivalent results were obtained by analyzing OS and by treating TMB as a continuous variable.

CONCLUSIONS

Our analysis failed to support application of TMB-H as a biomarker for treatment with ICB in all solid cancer types. Further tumor type-specific studies are warranted.

Abstract SP085: Metastatic TNBC - What’s new on the horizon?

Until very recently, the treatment for locally advanced or metastatic breast cancer revolved solely around sequential chemotherapies, alone or in combination. With the increasing recognition that triple negative breast cancers are a very heterogeneous group of tumors, exciting new strategies have emerged. Here we review some of the recent advances to standard chemotherapy now in clinical use as well discuss new strategies in development. Immunotherapy: There is currently an indication for nab-paclitaxel and atezolizumab for patients with locally advanced or metastatic triple negative breast cancer with PD-L1 positive tumor-infiltrating immune cells. The Impassion130 study first presented a median PFS of 7.2 months with nab-paclitaxel and atezolizumab vs. 5.5 months of nab-paclitaxel and placebo (HR 0.80; 95% confidence interval (CI) 0.69-0.92). Further analyses showed no benefit in the PD-L1 negative group.1 An exploratory overall survival analysis in the PD-L1+ subset showed an increase in the atezolizumab group of 25 months vs 18 in the control group.2 Immunotherapy for metastatic breast cancer will be presented in greater detail in another talk in this session. Sacituzumab govitecan: Sacituzumab govitecan is an antibody-drug conjugate (ADC) targeting Trop-2 and linked with SN-38, the active metabolite of irinotecan and a potent DNA- damaging agent. Trop-2 has been estimated to be expressed in up to 90% of TNBC, making it an attractive target for an ADC. Sacituzumab govitecan was conditionally approved for use after the Phase I/II trial demonstrated and objective response rate of 33.3% and a median overall survival of 13.0 months.3 The recently presented phase III ASCENT trial evaluated patients with metastatic TNBC who had at least 2 previous lines of therapy in the metastatic setting. There was an improvement in median PFS from 1.7 to 5.6 months for patients who received sacituzumab vs. physician’s choice of therapy. The HR for PFS was 0.41; 95% CI: 0.32-0.52) Additionally, there was an improvement in median OS of 6.7 to 12.1 months (HR 0.48; 95%CI:0.38-0.59).4PARP Inhibitors: There are now 2 PARP inhibitors that have FDA approval for use for patients with metastatic breast cancer and a germline BRCA pathogenic variant.5,6 Both Olaparib and Talazoparib demonstrated improvements in PFS which led to FDA approval. While neither the OlympiAD (olaparib) nor the EMBRACA (talazoparib) trial showed statistically significant improvement in OS, both trials showed a significant improvement in quality of life measures. Future Directions: Ongoing trials evaluating further ADCs, targeted therapies and drugs targeting DNA Damage Repair pathways for both germline and somatic pathogenic variants will be discussed

1.Schmid P, Adams S, Rugo HS, et al: Atezolizumab and Nab-Paclitaxel in Advanced Triple-Negative Breast Cancer. NEJM 379:2108-2121, 20182.Schmid P, Rugo HS, Adams S, et al: Atezolizumab plus nab-paclitaxel as first-line treatment for unresectable, locally advanced or metastatic triple-negative breast cancer The Lancet Oncology 21:44-59, 20203.Bardia A, Mayer IA, Diamond JR, et al: Efficacy and Safety of Anti-Trop-2 Antibody Drug Conjugate Sacituzumab Govitecan (IMMU-132) in Heavily Pretreated Patients With Metastatic Triple-Negative Breast Cancer. J Clin Oncol 35:2141-2148, 20174.Bardia A, Tolaney S, Loirat D, et al: ASCENT: A randomized phase III study of sacituzumab govitecan (SG) vs treatment of physician’s choice (TPC) in patients (pts) with previously treated metastatic triple-negative breast cancer (mTNBC). Annals of Oncology 31:S1142-S1215. 10.1016/annonc/annonc325, 20205.Robson M, Im S-A, Senkus E, et al: Olaparib for Metastatic Breast Cancer in Patients with a Germline BRCA Mutation. NEJM 377:523-533, 20176.Litton JK, Rugo HS, Ettl J, et al: Talazoparib in Patients with Advanced Breast Cancer and a Germline BRCA Mutation. NEJM 379:753-763, 2018

Citation Format: J Litton. Metastatic TNBC - What’s new on the horizon? [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SP085.

Talazoparib versus chemotherapy in patients with germline BRCA1/2-mutated HER2-negative advanced breast cancer: final overall survival results from the EMBRACA trial

BACKGROUND

In EMBRACA, talazoparib prolonged progression-free survival versus chemotherapy (hazard ratio [HR] 0.542 [95% confidence interval (CI) 0.413-0.711]; P < 0.0001) and improved patient-reported outcomes (PRO) in germline BRCA1/2 (gBRCA1/2)-mutated advanced breast cancer (ABC). We report final overall survival (OS).

PATIENTS AND METHODS

This randomized phase III trial enrolled patients with gBRCA1/2-mutated HER2-negative ABC. Patients received talazoparib or physician's choice of chemotherapy. OS was analyzed using stratified HR and log-rank test and prespecified rank-preserving structural failure time model to account for subsequent treatments.

RESULTS

A total of 431 patients were entered in a randomized study (287 talazoparib/144 chemotherapy) with 412 patients treated (286 talazoparib/126 chemotherapy). By 30 September 2019, 216 deaths (75.3%) occurred for talazoparib and 108 (75.0%) chemotherapy; median follow-up was 44.9 and 36.8 months, respectively. HR for OS with talazoparib versus chemotherapy was 0.848 (95% CI 0.670-1.073; P = 0.17); median (95% CI) 19.3 months (16.6-22.5 months) versus 19.5 months (17.4-22.4 months). Kaplan-Meier survival percentages (95% CI) for talazoparib versus chemotherapy: month 12, 71% (66% to 76%)/74% (66% to 81%); month 24, 42% (36% to 47%)/38% (30% to 47%); month 36, 27% (22% to 33%)/21% (14% to 29%). Most patients received subsequent treatments: for talazoparib and chemotherapy, 46.3%/41.7% received platinum and 4.5%/32.6% received a poly(ADP-ribose) polymerase (PARP) inhibitor, respectively. Adjusting for subsequent PARP and/or platinum use, HR for OS was 0.756 (95% bootstrap CI 0.503-1.029). Grade 3-4 adverse events occurred in 69.6% (talazoparib) and 64.3% (chemotherapy) patients, consistent with previous reports. Extended follow-up showed significant overall improvement and delay in time to definitive clinically meaningful deterioration in global health status/quality of life and breast symptoms favoring talazoparib versus chemotherapy (P < 0.01 for all), consistent with initial analyses.

CONCLUSIONS

In gBRCA1/2-mutated HER2-negative ABC, talazoparib did not significantly improve OS over chemotherapy; subsequent treatments may have impacted analysis. Safety was consistent with previous observations. PRO continued to favor talazoparib.

Progression-free survival (PFS) and toxicities of palbociclib in a geriatric population

PURPOSE

Over 40% of newly diagnosed metastatic breast cancer patients are ≥ 70 years old; however, this population is less likely to be represented in clinical trials. The objective of this study was to analyze PFS, dose reductions, dose delays, and toxicity in a geriatric population receiving palbociclib in a non-trial setting.

METHODS

Patients with metastatic breast cancer receiving palbociclib in any line of therapy were identified from a cohort of 845 patients at a large academic institution. Dose delays, dose reductions, and toxicities were retrospectively extracted from the medical record. Data were analyzed using Fischer's exact test for categorized variables and T test/Wilcoxon rank-sum test for continuous variables. PFS and OS were analyzed using the Kaplan-Meier method.

RESULTS

605 patients who met eligibility criteria were included. 160 patients were ≥ 65 years old and 92 patients were ≥ 70 years old. Patients ≥ 70 had a significantly increased number of dose reductions (p = 0.03) and dose delays (p = 0.02) compared to the younger patients. There was no significant increase in toxicities, including neutropenic fever, infections, or hospitalizations, in the ≥ 70 cohort (p = 0.3). The ≥ 70 cohort had a significantly improved PFS as compared to the younger cohort (p = 0.02); however, age was no longer a significant variable in the multivariate analysis.

CONCLUSIONS

Palbociclib was well tolerated in the geriatric population and there was no difference in PFS between older and younger patients. These results are reassuring as palbociclib becomes the frontline standard of care therapy for patients.

Abstract OT1-03-04: INTERACT- INTegrated Evaluation of Resistance and Actionability using Circulating Tumor DNA in hormone receptor (HR) positive metastatic breast cancers (MBC)

Background

Mutations in the ligand-binding domain of ESR1 have been demonstrated to mediate resistance to aromatase inhibitors (AI) and are associated with poor survival. Analyses of circulating tumor DNA (ctDNA) offer a minimally invasive and real-time approach to characterize genomic landscape, clonal evolution, and treatment response. Early detection and intervention with alternate therapy to overcome resistance at minimal disease burden progression could have a larger impact than treating higher burden disease at clinical progression. However, whether treatment decisions made based on the emergence of secondary resistance mutations or mutant allele fraction (MAF) changes in ctDNA can improve clinical outcomes is unknown. Currently, the most effective therapy for patients harboring ESR1 mutations is unclear; although, pre-clinical and retrospective clinical trial analyses have suggested that some of these mutations may exhibit greater sensitivity to fulvestrant, a selective estrogen receptor down-regulator, compared to AI. This study hypothesizes that real-time monitoring of ctDNA for secondary ESR1 alterations can identify subclinical progression and early intervention with a targeted-agent that has greater efficacy against ESR1 mutations can improve disease-free survival.

Trial Design

This is a randomized, open-label, Phase-2 study for HR-positive MBC patients who are on AI and CDK 4/6 inhibitor as first line therapy. Patients on treatment for at least 12 months without evidence of clinical progression would be screened for ESR1 mutations using Guardant360 ctDNA assay. Patients with positive ESR1 mutations would be randomized to change of endocrine therapy to fulvestrant vs. continuing AI.

Eligibility criteria

-Histologically confirmed HR-positive (ER and/or PR &gt;10%) and HER2-negative MBC

-On AI with CDK4/6 inhibitor as first line therapy for 12 months without evidence of clinical progression

-Activating ESR1 mutation identified on ctDNA

-ECOG performance status ≤1

-Normal organ and marrow function

Specific aims

- To assess progression-free survival (PFS) with transition to fulvestrant compared with continuing AI therapy in patients with emergence of ESR1 mutations in plasma

-To assess ctDNA ESR1 mutant allele fraction and kinetics with transition to fulvestrant compared with AI

-To assess the prevalence of ESR1 mutations in patients with exposure to endocrine therapy

-To assess overall survival with fulvestrant transition compared with continuing AI therapy in patients with emergence of ESR1 mutations

Statistical methods

To detect a change in median PFS from 5 months (for AI arm) to 9 months (with fulvestrant arm) would require about 124 patients (5% two-sided alpha, 80% power, log rank testing). Interim analysis will be performed when 42 PFS events are observed. Using O'Brien-Fleming stopping boundaries, we will stop for futility if the log rank test p-value &gt; 0.72 and stop for success if it is &lt; 0.004.

Citation Format: Damodaran S, Meric-Bernstam F, Hess KR, Litton JK, Raymond V, Lanman R, Ueno NT, Hamilton S, Wistuba II, Valero V, Moulder SL, Tripathy D. INTERACT- INTegrated Evaluation of Resistance and Actionability using Circulating Tumor DNA in hormone receptor (HR) positive metastatic breast cancers (MBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT1-03-04.

Abstract P6-18-12: EMBRACA: Efficacy and safety of talazoparib or physician's choice of therapy in patients with advanced breast cancer and a germline BRCA1/2 mutation: A regional analysis

Background: Talazoparib (TAL) prevents DNA damage repair by inhibiting poly (ADP-ribose) polymerase (PARP) enzymes and trapping PARP on DNA, resulting in cell death in BRCA1/2-mutated cells.

Methods: EMBRACA is an open-label, randomized, 2-arm phase 3 trial in which efficacy and safety of TAL (1 mg/d) were compared with physician's choice of therapy (PCT; capecitabine, eribulin, gemcitabine, vinorelbine) in patients (pts) with locally advanced or metastatic breast cancer (ABC) and a germline BRCA mutation (gBRCAm). Outcomes were assessed by region of the world (North America [NA]; Europe [EU]; rest of world [ROW]). Progression-free survival (PFS), objective response rate (ORR), and clinical benefit rate (CBR) at 24 wks were assessed; safety was also assessed.

Results: 431 pts were randomized 2:1. Pt characteristics were well balanced, although a higher percentage of pts in ROW had more severe disease (eg, triple-negative breast cancer [TNBC], Disease-free interval [DFI]&lt;12 mo, more distant metastases, more disease sites) and were on average younger than pts in NA/EU. TAL provided improvement in PFS, ORR, and CBR in all regions vs PCT. The most common toxicities with TAL included anemia, neutropenia, thrombocytopenia, fatigue, and nausea for all regions. Alopecia was less frequent with TAL in EU/ROW. Serious adverse events for pts receiving TAL were more frequent in EU than NA/ROW. Incidences of adverse events associated with permanent treatment discontinuation in pts receiving TAL were low in all regions and generally lower than for PCT.

Table 1CategoryNA* (N=156)EU* (N=190)ROW* (N=85)Mean age, years49.049.244.2Race, %   White76.971.152.9Black5.8-3.5Asian5.8-42.4Not reported-27.4-TNBC, %424447BRCA1**, %414748BRCA2**, %595352DFI&lt;12 mo, %313444Distant metastases, %949397≥3 disease sites, %474049PFS, (hazard ratio [HR]; [95% CI]); P value0.46 [0.29-0.74] P=.00090.52 [0.33-0.80]; P&lt;.0030.57 [0.31-1.07] ;P=.08ORR (odds ratio [OR] [95% CI]); P value5.54 [2.4-16.1];P&lt;.00013.75 [1.57-9.87]; P=.0016.7 [1.61-28.39]; P=.001CBR (OR [95% CI]); P value4.71 [2.20-10.57]; P&lt;.00013.39 [1.56-7.36]; P=.00075.70 [1.70-17.13]; P=.002Hematologic AEs, %   Anemia50.558.642.6Neutropenia31.332.346.3Thrombocytopenia28.322.635.2Nonhematologic AEs, %   Fatigue59.643.650.0Nausea47.545.957.4Headache32.330.837.0Alopecia34.320.320.4Serious adverse events, %25.340.622.2Treatment discontinuation, n/N, (%)   TAL7/99 (7.1)12/133 (9.0)3/54 (5.6)PCT7/43 (16.3)3/54 (5.6)2/29 (6.9)AE, adverse event; CI, confidence interval; *NA (United States); EU (Belgium, France, Germany, Ireland, Italy, Poland, Spain, United Kingdom, Russia, Ukraine, Israel); ROW (Brazil, Korea, Australia, Taiwan).**Central laboratory.

Conclusions: In pts with gBRCAm ABC, TAL demonstrated significant improvements in clinical outcomes compared with PCT regardless of the region of the world in which they lived. However, slight differences among the regions in baseline characteristics were noted, possibly due to regional variation in diagnosis and detection of gBRCAm ABC as well as different treatment paradigms for metastatic breast cancer.

Funding: Medivation LLC, acquired by Pfizer.

Citation Format: Mina L, Lee K-H, Gonçalves A, Woodward N, Hurvitz SA, Diab S, Yerushalmi R, Goodwin A, Moreira Costa Zorzetto M, Kim S-B, Czibere A, Tudor IC, Gauthier E, Litton JK, Ettl J. EMBRACA: Efficacy and safety of talazoparib or physician's choice of therapy in patients with advanced breast cancer and a germline BRCA1/2 mutation: A regional analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-12.

Abstract OT3-03-02: A phase 2, open-label, single-arm, multi-center study of talazoparib for neoadjuvant treatment of germline BRCA1/2 mutation patients with early-stage triple-negative breast cancer (TNBC)

Background: Approximately 15% of all breast cancers are triple negative and deleterious BRCA1/2 mutations are found in ˜11% of unselected TNBC. In the phase 3 EMBRACA trial (NCT01945775), the poly (ADP-ribose) polymerase (PARP) inhibitor talazoparib was superior to chemotherapy in prolonging progression-free survival in BRCA1/2 mutation patients with advanced breast cancer. A recent pilot study (NCT02282345) of 20 patients, explored the feasibility of neoadjuvant talazoparib in BRCA1/2 mutation patients; pathologic complete response (pCR) was reported at 53% with 6 months of single agent talazoparib.

Trial Design: This phase 2, single-arm, open-label, multi-center study has a Simon 2-stage design. Eligible pts have stage I-III invasive TNBC (ER and PR &lt;10%), with germline BRCA1/2 mutations who are suitable for neoadjuvant therapy. Pts will receive talazoparib 1 mg daily for 24 weeks, followed by breast surgery, which should occur within 4 to 6 weeks of the last dose. Ultrasound will be performed serially to assess tumor response. The primary objective is to evaluate pCR after 24 weeks of neoadjuvant talazoparib. pCR (ypT0/is ypN0) will be assessed by independent central review. Safety will also be assessed. Pts will be followed for at least 5 years to assess long term outcomes (event-free and overall survival). After surgery, any further adjuvant therapy will be given at the discretion of the treating physician. Pt reported outcomes will be assessed electronically including the global health status/quality of life, functions, and symptoms using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaires C30 and BR23. Plasma pharmacokinetic (PK) samples for determination of talazoparib concentrations will be collected at defined timepoints to describe the steady-state PK of talazoparib. Exploratory biomarker research will also take place. Approximately 122 men and women will be enrolled in the study, of which 112 evaluable pts are planned. With 112 evaluable pts and one interim futility look, the null hypothesis that the true pCR rate is 35% will be tested against a 1-sided alternative. This design yields a 1-sided type 1 error rate of 2.5% and power of 90% when the true pCR rate is 50%. An interim analysis will be performed to evaluate the efficacy of talazoparib after 28 evaluable pts undergo talazoparib treatment for 24 weeks, followed by surgery, and are assessed for pCR by central review. This trial is currently recruiting and is registered at clinicaltrials.gov (NCT03499353).

Funding: This study is sponsored by Pfizer, Inc.

Citation Format: Litton J, Symmans F, Gogineni K, Saltzman M, Telli ML, Usha L, Chakrabarti J, Tudor IC, Quek RG, Czibere A. A phase 2, open-label, single-arm, multi-center study of talazoparib for neoadjuvant treatment of germline BRCA1/2 mutation patients with early-stage triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT3-03-02.

Abstract P2-09-01: Subgroups analysis of a multicenter, prospective, randomized, blinded phase 2b trial of trastuzumab + nelipeptimut-S (NeuVax) vs trastuzumab for prevention of recurrence in breast cancer patients

Background:HER2 low-expressing (LE) (IHC 1-2+, FISH non-amplified) breast cancer (BC) patients (pts) have not benefited from HER2-directed therapy despite HER2 antigen availability. Triple negative BC (TNBC), in particular, is immunogenic and in need of additional therapeutic options. We have previously shown the HER2-derived nelipeptimut-S (E75) + GM-CSF (NeuVax) to be synergistic with trastuzumab (Tz) in pre-clinical and pilot clinical studies. In a planned interim analysis of a multi-center, prospective, randomized, single-blinded, placebo-controlled phase 2b trial of Tz + NeuVax vs Tz to reduce recurrence in HER2 LE, node-positive (NP) and/or triple negative BC (TNBC) pts, we previously reported that the NeuVax + Tz was safe without added cardiac toxicity and demonstrated a significant reduction of recurrences in TNBC pts. This analysis examines additional subsets in this trial.

Methods:HER2 LE, NP and/or TNBC pts who were clinically disease-free after standard therapy were randomized to receive Tz+NeuVax (vaccine group; VG) or Tz+GM-CSF (control group; CG). All pts received 1 yr of Tz per label. NeuVax or GM-CSF was given every 3 weeks x 6 starting with the 3rdTz dose, and then boosted every 6 months x 4. This pre-specified interim analysis was triggered 6 months after last enrollment. The primary endpoint is intention-to-treat 24 month disease-free survival (DFS) evaluated by log rank.

Results: Of 275 pts randomized in the study (VG n=136, CG n=139), 98 had TNBC (VG=53, CG=45). In the interim analysis, estimated disease-free survival (DFS) was assessed with a median follow up of 18.8 months. No significant clinicopathologic differences were seen between treatment groups. In the TNBC group, estimated DFS was higher overall in VG vs CG (91.9% v 69.9%, p=0.023; hazard ratio [HR] 0.29, 95% confidence interval [CI] 0.09-0.90). On TNBC subgroup analysis, estimated DFS was higher in VG vs CG among pts who received neoadjuvant chemotherapy (VG n=35, CG n=31; HR 0.26, CI 0.07-0.93; p=0.03), HER2 IHC 1+ BC (VG n=34, CG n=28; HR 0.20, CI 0.04-0.96; p=0.03), pts who were AJCC 7thedition stage I/II (VG n=37, CG n=27; HR incalculable, no recurrences in the VG, p=0.008), and pts 351yr of age (VG n=32 & CG n = 26; HR 0.26 CI 0.07,0.94; p=0.009). HRs did not appreciably vary based on the histologic grade or presence of lymphovascular invasion.

Conclusion:Examining the subgroups from the pre-specified interim analysis demonstrates a highly significant clinical benefit in TNBC pts overall. Within the TNBC cohort, specific benefit was seen in pts who received chemotherapy neoadjuvantly, expressed lower HER2, were earlier stage, and were older in age. These factors may help enrich the TNBC population targeted in a definitive Phase 3 study in TNBC patients with residual disease after neoadjuvant chemotherapy.

Citation Format: Clifton GT, Kemp Bohan PM, Hale DF, Myers JW, Brown TA, Holmes JP, Vreeland TJ, Litton JK, Murthy RK, Mittendorf EA, Peoples GE. Subgroups analysis of a multicenter, prospective, randomized, blinded phase 2b trial of trastuzumab + nelipeptimut-S (NeuVax) vs trastuzumab for prevention of recurrence in breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-01.

Abstract P6-17-04: 3-year relapse-free survival of stage II-III HER2-neu positive breast cancer treated with pertuzumab and trastuzumab-containing neoadjuvant therapy compared to trastuzumab-containing therapy

Background: Pertuzumab (P) in combination with trastuzumab (H) based chemotherapy is FDA-approved as a standard neoadjuvant treatment for patients with clinical stage II-III HER2-positive (HER2+) breast cancer (BC). The goal of this study was to evaluate the pathologic complete response (pCR) rate for neoadjuvant HP-containing regimens compared to H-containing regimens and report the 3-year relapse-free survival (RFS) for patients who had a pCR compared to those with residual disease (RD).

Methods: All patients with stage II-III non-inflammatory HER2+ BC who received neoadjuvant H-containing or HP-containing therapy and underwent definitive breast and axillary surgery were identified from 2005 to 2016 through an institutional database. Medical records were examined for patient demographics, breast cancer stage, pathology results, surgical outcomes, and treatment details. pCR was defined as ypT0/is, ypN0. RFS was defined as the interval from surgery to date of last followup or death from any cause. Descriptive statistics, Cox proportional hazards, and Kaplan-Meier estimates were used for statistical analysis.

Results: Patient characteristics and results by pCR or RD status are shown in the table below. The median age was 51 (22-84) years for the HP group and 50 (21-87) years for the H group. The median follow-up time was 1.9 (0-4.2) years for the HP group and 5.3 (0.1-12) years for the H group. For the HP group, the 3-year RFS was 98% (95% CI: 95, 100) for the pCR group and 90% (95% CI: 83, 97) for the RD group; HR 0.17 (0.04, 0.82), p=0.012. For the H group, the 3-year RFS was 91% (95% CI: 88,94) for the pCR group and 75% (95% CI: 71-79) for the RD group; HR 0.31 (0.22, 0.44), p&lt;0.0001. Among the 520 patients who achieved pCR and the 502 patients who had RD, the effect of HP vs. H was statistically significant (pCR: HR 0.24 (0.06, 1.00); p=0.015) (no pCR: HR 0.46 (0.22, 0.94); p=0.017).

Conclusion: Patients who achieve pCR have an improved 3-year RFS compared to patients who have RD. Treatment with HP-containing neoadjuvant regimens is associated with a high 3-year RFS.

VariableHP (n=215)H (n=807)  pCR n=121RD n=94pCR n=399RD n= 408Age at Diagnosis&lt;5043%46%46%51% ≥5057%54%54%49%Menopausal StatusPremenopausal46%50%53%57% Postmenopausal54%50%47%43%Clinical Stage at DiagnosisIIA40%29%34%29% IIB29%31%23%28% IIIA14%15%17%16% IIIB0%5%5%9% IIIC17%20%21%18%Clinical Nodal StatusNode (+)63%76%69%73% Node (-)37%24%31%27%Nuclear Grade1II25%32%22%28% III75%65%78%72%HR statusHR(+)52%74%52%67% HR(-)48%26%48%33%Adjuvant therapyTrastuzumab88%80%100%100% Trastuzumab and Pertuzumab3%5%0%0% Unknown9%15%20%0%11 patient in the HP pCR group had nuclear grade 1; 2 patients in the HP RD group had nuclear grade 1 tumors 2 2 patients received adjuvant TDM-1 on the NSABP B50 protocol

Citation Format: Murthy RK, Raghavendra AS, Hess KR, Barcenas CH, Lim B, Moulder SL, Giordano SH, Mittendorf EA, Thompson A, Ueno NT, Valero V, Litton JK, Tripathy D, Chavez-Macgregor M. 3-year relapse-free survival of stage II-III HER2-neu positive breast cancer treated with pertuzumab and trastuzumab-containing neoadjuvant therapy compared to trastuzumab-containing therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-04.

Revisiting the definition of estrogen receptor positivity in HER2-negative primary breast cancer

Background

Although 1% has been used as cut-off for estrogen receptor (ER) positivity, several studies have reported that tumors with ER < 1% have characteristics similar to those with 1% ≤ ER < 10%. We hypothesized that in patients with human epidermal growth factor 2 (HER2)-negative breast cancer, a cut-off of 10% is more useful than one of 1% in discriminating for both a better pathological complete response (pCR) rate to neoadjuvant chemotherapy and a better long-term outcome with adjuvant hormonal therapy. Our objectives were to identify a percentage of ER expression below which pCR was likely and to determine whether this cut-off value can identify patients who would benefit from adjuvant hormonal therapy.

Patients and methods

Patients with stage II or III HER2-negative primary breast cancer who received neoadjuvant chemotherapy followed by definitive surgery between June 1982 and June 2013 were included. Logistic regression models were used to assess the association between each variable and pCR. Cox models were used to analyze time to recurrence and overall survival. The recursive partitioning and regression trees method was used to calculate the cut-off value of ER expression.

Results

A total of 3055 patients were analyzed. Low percentage of ER was significantly associated with high pCR rate (OR = 0.99, 95% CI = 0.986-0.994, P < 0.001). The recommended cut-off of ER expression below which pCR was likely was 9.5%. Among patients with ER ≥ 10% tumors, but not those with 1%≤ER < 10% tumors, adjuvant hormonal therapy was significantly associated with long time to recurrence (HR = 0.24, 95% CI = 0.16-0.36, P < 0.001) and overall survival (HR = 0.32, 95% CI = 0.2-0.5, P < 0.001).

Conclusion

Stage II or III HER2-negative primary breast cancer with ER < 10% behaves clinically like triple-negative breast cancer in terms of pCR and survival outcomes and patients with such tumors may have a limited benefit from adjuvant hormonal therapy. It may be more clinically relevant to define triple-negative breast cancer as HER2-negative breast cancer with <10%, rather than <1%, of ER and/or progesterone receptor expression.

Abstract P4-02-04: Quantitative MRI features analysis for differentiation of triple negative and HER2 positive subtypes of breast cancer

Objective: The aim of this study was to evaluate ability of quantitative analysis of MRI features to distinguish triple negative (TN) and HER2 positive (HER2+) subtypes of breast cancer, which have different biological characteristics, exhibiting different growth patterns and response to treatment.

Materials and Method: Breast cancer patients, who had MRI exam of the breast in our institution at the time of staging for breast carcinoma and who subsequently had surgery (segmentectomy or mastectomy) from January 1, 2008 through December 31, 2015 were identified. All lesions were evaluated by radiologists in accordance with the BI-RADS lexicon. The patient's age, breast cancer histology, multifocality/multicentricity (MF/MC), lesion size, axillary lymphadenopathy (LAN), MRI morphologic and enhancement characteristics were documented. Quantitative MRI feature analysis was performed using shape, texture, and histogram based features. Machine-learning-based (Xgboost) models were used to predict subtypes, and Leave-one-out cross-validation (LOOCV) was used to avoid model overfitting. Statistical significance was determined using the Student's t-test.

Results: Total of 105 patients, 51 patients with TN and 54 patients with HER2+ breast cancer were included in analysis. Mean age for TN was 50 (range 29-79)) years old and for HER2+ was 49 (range 25-70) years old. Axillary LAN and MF/MC disease was seen more commonly in HER2+ patients when compared to TN patients, but didn't reach statistical significance (13 vs 7, p=0.9; and 31 vs 20, p=0.06, respectively). Mass rim enhancement was associated with TN subtype and irregular mass enhancement was associated with HER2+ subtype of breast cancer (p&lt;0.05). Quantitative analysis showed that six out of the top 10 ranked MRI features: surface to volume ratio, difference variance, difference entropy, inverse difference moment, 75 percentile in histogram and sum average, were significantly different between these 2 subtypes with p&lt;0.05. When the significant features were incorporated to distinguish TN and HER+ subtypes, use of the top 2 features achieved the best accuracy on LOOCV of 0.69.

Conclusion: The quantitative MRI features show promise in distinguishing TN and HER2+ breast cancer subtypes reflecting their underlying biological characteristics and may be used as predictive quantitative biological markers. Further studies in a larger cohort evaluating associations with treatment response are underway.

FeatureIndexP-valueSurface to volume ratioShape30.005Difference VarianceGLCM110.005Difference EntropyGLCM100.009Inverse Difference MomentGLCM50.01875 percentile in histogramHistogram50.043Sum AverageGLCM60.044Median in histogramHistogram 30.08025 percentile in histogramHistogram 40.095VolumeShape10.104Max in histogramHistogram 10.105

Citation Format: Rauch GM, Li H, Zhu H, Adrada BE, Santiago L, Candelaria RP, Wang H, Leung J, Thompson A, Litton J, Wu Y, Lim B, Moulder S, Mittendorf EA, Yang W. Quantitative MRI features analysis for differentiation of triple negative and HER2 positive subtypes of breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-02-04.

Abstract P5-05-01: A molecularly annotated collection of breast cancer patient-derived xenograft models aligned with ongoing clinical trials built from fine needle aspiration samples throughout neoadjuvant treatment

BACKGROUND: Patient-derived xenograft (PDX) models of breast cancer replicate the diverse histologic and molecular features of patient tumors and provide a renewable source of human tumor tissue. However, collection of tissue by core needle biopsy is problematic due to patient discomfort, bleeding risk and the limited number of passes a patient can tolerate. Several studies have catalogued the maintenance of molecular features of patient tumors in PDX models of breast cancer.

METHODS: To support the neoadjuvant molecular diagnostic and drug development program in triple negative breast cancer (TNBC), a pilot study was conducted to determine if fine needle aspiration (FNA) could be used for building PDX models. Subsequently, PDX models are being established in alignment with ongoing clinical trials at MDACC. The molecular evolution of patient's tumors, matched with PDXs engrafted from their tumors, is under study throughout the neoadjuvant treatment of TNBC using RNA sequencing, whole-exome sequencing, deep sequencing of cancer genes, and histologic analyses.

RESULTS: To date, 20 established PDX models have been developed and stable PDX models continue to be generated at a rate of 2-3 per month. Several of these models are derived from serial FNAs derived from patients throughout neoadjuvant treatment. These models retain histologic and molecular features of the original patient tumors. Serial patient biopsies, matched with PDX models, have enabled measurement of the mutational and transcriptomic evolution in vivo of TNBC undergoing neoadjuvant treatment.

We have standardized the use of FNAs to generate PDX models both pre- and post-neoadjuvant therapy in the following ongoing neoadjuvant clinical trials:

1. MDACC 2014-0185 (PI Stacy Moulder, 360 patients), 'ARTEMIS: A Randomized TNBC-Enrolling trial to confirm Molecular profiling Improves Survival'

2. MDACC 2014-0045 (PI Jennifer Litton, 20+ patients), 'A pilot study of BMN673 as a neoadjuvant study in patients with a diagnosis of invasive breast cancer and a deleterious BRCA mutation'

CONCLUSION: We demonstrated that PDX models from tissue collected by FNA recapitulate the biology and clinical course of the patient's tumor. Sequencing analyses revealed that neoadjuvant chemotherapy and PDX engraftment enrich for cancer gene mutations. We observe association of the rate of successful PDX engraftment with clinical parameters such as the patient's residual cancer burden (RCB) status at the time of surgery (upon completion of neoadjuvant treatment). In addition, we observe that PDX models derived from serial patient biopsies throughout treatment are more resistant to chemotherapy treatment. These models recapitulate the variety of chemotherapy responses observed in patients with TNBC and serve as powerful tools for preclinical biomarker and discovery studies.

Citation Format: Echeverria GV, Cai S, Tu Y, McCoy A, Lau R, Redwood A, Rauch G, Adrada B, Candelaria R, Santiago L, Thompson A, Litton J, Moulder S, Symmans F, Chang JT, Piwnica-Worms H. A molecularly annotated collection of breast cancer patient-derived xenograft models aligned with ongoing clinical trials built from fine needle aspiration samples throughout neoadjuvant treatment [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-05-01.

Abstract PD2-09: Association of quantitative MRI features with tumor infiltrating lymphocytes and treatment response prediction in HER2 positive subtype of breast cancer

Objectives: To evaluate associations between qualitative and quantitative MRI features and tumor infiltrating lymphocytes (TIL) levels in HER2+ subtype of breast cancer, as potential prognostic non-invasive imaging markers for treatment response prediction.

Materials and Methods: Retrospective review of breast cancer patients who had MRI at staging, neoadjuvant chemotherapy and surgery from January 1, 2008 through December 31, 2015 was performed. BI-RADS lexicon was used for lesion evaluation. Demographic, imaging, and pathologic data including TIL levels were documented. Quantitative MRI texture analysis was performed using 3 types of textural features (TF): local binary patterns (LBP), gray-level co-occurrence matrix (GLCM), and threshold adjacency statistics (TAS). Associations between MRI quantitative TF, TIL levels, and pathologic complete response (pCR) were evaluated by Pearson correlation and logistic regression.

Results: There were 50 HER2+ patients (median age 51 years, range 29-59) with pretreatment MRI and TIL status for analysis; 27 patients had pCR at surgery. Qualitative MRI analysis showed that mass rim-enhancement (p&lt;0. 05) and fast early enhancement kinetics (p&lt;0.01) were associated with higher TIL levels. No association between qualitative MRI features and pCR was found. Nine TF significantly correlated with pCR (p&lt;0.05): angular 2nd moment (GLCM), 75 percentile (LBP), standard deviation (GLCM), adjacency 0-5 (TAS). This is indicative of association of tumor heterogeneity with pCR. Three TF were significantly associated with high TIL levels (p&lt;0.05): standard deviation, adjacency 1 and 2. Additional four TF had high association with TIL (p&lt;0.1): sum entropy, adjacency 0, 3 and 4. These findings showed that increased heterogeneity, complexity and entropy were associated with high TIL level. Three TF were significantly associated with both, pCR and TIL (p&lt;0.05): 75 percentile, standard deviation, adjacency 8.

Conclusion: Quantitative tumor texture analysis based on statistical modeling showed specific nine TF indicative of tumor heterogeneity associated with pCR; and seven TF indicative of increased heterogeneity, complexity, and entropy associated with high TIL levels in HER2+ breast cancer. Analysis of associations of MRI quantitative TF with pCR and TIL in HER2+ breast cancer may help to develop prognostic non-invasive imaging markers for treatment response prediction.

Citation Format: Rauch GM, Zhu H, Li H, Adrada BE, Santiago L, Candelaria RP, Wang H, Leung J, Litton J, Wu Y, Murthy R, Mittendorf EA, Yang W. Association of quantitative MRI features with tumor infiltrating lymphocytes and treatment response prediction in HER2 positive subtype of breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD2-09.

Abstract P6-03-05: Risk of needle-track seeding with serial ultrasound guided biopsies in triple negative breast cancer

Background: Image-guided percutaneous needle biopsy of the breast is a common procedure. In breast cancer patients (pts) undergoing core biopsies and surgical resection on the same day, the rate of tumor cell displacement along the needle track has been reported to be up to 50%. However, the clinical significance of this finding in triple negative breast cancer (TNBC) patients (pts) undergoing serial biopsies while receiving neoadjuvant chemotherapy (NACT) is unknown. Here we report the incidence of needle-track seeding (NTS) in a cohort of TNBC pts enrolled on a molecular triaging protocol involving serial biopsies of the index breast lesion.

Methods: We reviewed the clinical records of 144 consecutive TNBC pts enrolled on a molecular triaging protocol at MD Anderson Cancer Center. Per protocol, all pts underwent a pre-treatment research biopsy and were initiated on anthracycline based NACT (AC). Pts with inadequate response to front-line NACT were encouraged to undergo additional biopsies of the index breast lesion prior to switching therapies. Serial breast ultrasound (US) was performed to monitor therapeutic response and incidental evidence of needle-track seeding noted on US was documented.

Results: Clinicopathological characteristics of the pts are summarized in Table 1. 89% (128/144) of pts had a diagnostic breast biopsy done at another center prior to presenting at MDACC. To date, we have performed 209 US guided biopsies of index breast lesions in 144 pts. 92% (193/209) of these biopsies were done mainly for research purposes. 1.4% (2/144) of pts were found to have evidence of NTS on follow up US. The first pt had a T1N0 (1.9cm), grade 3, invasive ductal carcinoma (IDC) at diagnosis. She underwent a diagnostic biopsy followed by a research biopsy before initiating AC. She was found to have NTS as well as progression of disease (PD) on follow up US after 2 cycles of AC. The second pt had a T2N0 (3cm), grade 3 IDC at diagnosis. She underwent a diagnostic biopsy at another center, followed by a research biopsy before initiating AC. Like the first pt, she was found to have NTS and PD on follow up US after 2 cycles of AC. Both pts are currently on neoadjuvant clinical trials of novel agents.

Conclusion: The rate of NTS detected on US in TNBC pts undergoing serial biopsies of index breast lesions while receiving NACT is low and further studies are needed to determine the impact of serial biopsies on long term outcomes in TNBC.

Table 1: Patient CharacteristicsCharacteristicN=144Age - Median (years, interquartile range)55 (46-62)Tumor Size Mean (cm, standard deviation)3.4 (2.2)T1 – n(%)35 (24)T2 – n(%)89 (62)T3 – n(%)19 (13)T4 – n(%)1 (1)Clinical Nodal Status Negative – n(%)74 (51)Positive – n(%)70 (49)Grade 1 – n(%)1 (1)2 – n(%)17 (12)3 – n(%)124 (86)Unknown – n(%)2 (1)Histologic Subtype Invasive ductal carcinoma – n(%)121 (84)Invasive lobular carcinoma – n(%)2 (1)Mixed ductal and lobular carcinoma – n(%)3 (2)Metaplastic carcinoma – n(%)13 (9)Not specified – n(%)5 (3)Laterality Right – n(%)72 (50)Left – n(%)72 (50)

Citation Format: Yam C, Santiago L, Candelaria RP, Adrada BE, Rauch GM, Hess KR, Litton JK, Piwnica-Worms H, Mittendorf EA, Ueno NT, Lim B, Murthy RK, Damodaran S, Helgason T, Huo L, Thompson AM, Gilcrease MZ, Symmans WF, Moulder SL, Yang W. Risk of needle-track seeding with serial ultrasound guided biopsies in triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-03-05.

Abstract P1-16-01: Tumor subtype concordance between breast and bone biopsies in bone only metastasis patients

Background:

Bone is the most common site of metastasis in metastatic breast cancer patients. Notably, bone biopsy is considered technically challenging with concerns regarding yield and reproducibility of immunohistochemistry technique. Our goal was to assess tumor subtype concordance between breast and bone biopsies done in patients with bone only metastases.

Methods:

We identified patients followed at MD Anderson Cancer Center for at least 6 months from 01/01/1997 to 12/31/2015 with bone as first site of metastasis. Breast and bone biopsy immunohistochemistry was used to categorize tumor subtype with hormone receptor positive (HR+) defined as ER or PR &gt;1%. The following four tumor subtypes were identified: luminal A-like (HR+, HER2-), luminal B-like (HR+, HER2+), triple negative (HR-, HER2-), and HER positive (HR-, HER2+).

Results:

We identified 805 bone only metastasis patients with positive bone biopsies, 395 (49%) of which had hormone receptor and HER2 characterization available. Of these 395 patients, 293 (74%) were luminal A-like, 44 (11%) were luminal B-like, 51 (13%) were triple negative, and 7 (2%) were HER2 positive. Of these patients, we identified 281 patients with tumor subtype data available for both primary breast biopsy and bone metastasis biopsy, of which 237 (84%) were concordant, while 44 (16%) were discordant (Table 1).

Table 1. Concordance between breast and bone biopsies based on initial breast biopsy tumor subtypeBreast Biopsy Tumor Subtype (n = 281)Concordance with Bone Biopsy Tumor SubtypeDiscordant Bone Biopsy Tumor SubtypeLuminal A-like, HR+ HER2- (225/80%)Concordant: 199 (88%), Discordant: 26 (12%)10 Luminal B-like, 16 Triple negativeLuminal B-like, HR+ HER2+ (33/12%)Concordant: 19 (58%), Discordant: 14 (42%)11 Luminal A-like, 2 Triple negative, 1 HER2 positiveTriple negative, HR- HER2- (20/7%)Concordant: 16 (80%), Discordant: 4 (20%)3 Luminal A-like, 1 Luminal B-likeHER2 positive, HR- HER2+ (3/1%)Concordant: 3 (100%), Discordant: 0 (0%)NA

Conclusions:

When available, bone biopsy tumor subtype had significant concordance with breast biopsy tumor subtype in this large study of bone only metastasis patients. Discordant tumor subtype results were more common in patients with luminal B-like tumor subtype on initial breast biopsy.

Citation Format: Parkes AM, Clifton KK, Al Awadhi A, Oke OC, Warneke CL, Litton JK, Hortobagyi GN. Tumor subtype concordance between breast and bone biopsies in bone only metastasis patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-16-01.

Abstract P3-04-11: Implications of somatic TP53 and PIK3CA mutations in patients with metastatic breast cancer who underwent germline BRCA testing

Background: TP53 and PIK3CA are the most frequently mutated genes in breast cancer. However, there is limited data evaluating the impact of somatic mutations in TP53 and/or PIK3CA patients (pts) with metastatic breast cancer (MBC) who have undergone germline testing for BRCA mutations. Here, we report the frequency of somatic TP53 and PIK3CA mutations in MBC pts who previously underwent germline BRCA (gBRCA) testing and evaluate their impact on long-term outcomes.

Methods: We identified pts with MBC from our prospectively maintained high risk genetics database who underwent gBRCA testing and had somatic mutation testing performed for TP53 and/or PIK3CA through hotspot sequencing of single genes or as part of a next generation sequencing panel. Univariable logistic regression was used to evaluate associations between clinicopathological characteristics, including gBRCA status, and the presence of somatic TP53 and PIK3CA mutations. Overall survival (OS) was defined as the time from diagnosis to death from any cause. Multivariable cox regression analysis was used to identify independent predictors of OS.

Results: 104 pts met all inclusion criteria. Somatic mutations in TP53 and PIK3CA were found in 46% (39/84) and 23% (24/104) of tested pts, respectively. Associations between clinicopathological characteristics and somatic TP53 and PIK3CA mutation status are summarized in Table 1. Pts with hormone receptor positive (HR+) disease were less likely to have TP53 mutations (odds ratio [OR]: 0.28, 95% confidence interval [CI]: 0.11-0.70, p=0.007) but more likely to harbor PIK3CA mutations (OR: 3.27, 95% CI: 1.11-9.62, p=0.031). There were no significant associations between gBRCA mutation status and somatic TP53 or PIK3CA mutations. On multivariable analysis, somatic TP53 mutations (adjusted hazard ratio [aHR]: 1.98, 95% CI: 1.10-3.58, p=0.023) and de novo metastatic disease (aHR=2.88, 95% CI: 1.26-6.58, p=0.012) independently predicted poorer OS, while HR+ disease (aHR: 0.40, 95% CI: 0.21-0.74, p=0.004) and HER2+ disease (aHR: 0.33, 95% CI: 0.13-0.83, p=0.019) were significantly associated with improved OS. PIK3CA mutations (aHR: 1.20, 95% CI: 0.59-2.44, p=0.62) and gBRCA mutations (aHR: 0.78, 95% CI: 0.33-1.83, p=0.57) did not significantly impact OS in this study.

Conclusion: In this study, somatic TP53 mutations independently predicted worse OS in pts with MBC after adjusting for significant covariates, including gBRCA mutation status. These findings should be validated in a larger cohort of pts.

Table 1: Association between patient characteristics and somatic TP53 and PIK3CA mutation status TP53  PIK3CA   TP53 mutant (n=39)TP53 wild type (n=45)p valuePIK3CA mutant (n=24)PIK3CA wild type (n=80)p valueMedian Age – years (Interquartile Range)37 (33-47)39 (36-44)0.93739 (34-46)38 (34-43)0.494gBRCA mutant – n(%)3 (8)11 (24)0.0511 (4)15 (19)0.116ER/PR positive - n(%)17 (44)33 (73)0.00719 (79)43 (54)0.031HER2 positive - n(%)8 (21)6 (13)0.3827 (29)10 (13)0.060De Novo Metastatic – n(%)6 (15)8 (18)0.7693 (13)16 (20)0.409Visceral Disease – n(%)23 (59)26 (58)0.91215 (63)47 (59)0.743

Citation Format: Yam C, Gutierrez Barrera A, Huang D, Lin X, Litton JK, Arun B. Implications of somatic TP53 and PIK3CA mutations in patients with metastatic breast cancer who underwent germline BRCA testing [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-04-11.

Abstract P3-11-03: The impact of dose delays and reductions on toxicity and progression free survival (PFS) in patients receiving palbociclib

Background: Despite the high rates of neutropenia observed in the PALOMA studies, the incidence of neutropenic fevers remained low. The safety analysis from the PALOMA-3 trial showed no difference in PFS among pts who had dose reductions or delays secondary to neutropenia. We conducted a retrospective study to analyze the impact of dose delays and reductions on toxicity and progression free survival (PFS) in pts receiving palbociclib as standard of care.

Methods: Pts with metastatic ER positive breast cancer receiving palbociclib in any line of therapy were identified from a cohort at MD Anderson Cancer Center. Clinical, demographic, baseline labs, comorbidities and recurrence data were collected. Dose delays, dose reductions, and toxicities were recorded up to the first 6 cycles of palbociclib. Early dose delays and reductions were defined as events occurring during the first 2 cycles of palbociclib while late events were defined as cycles 3-6. Data was analyzed using Fischer's exact test for categorized variables and T test/Wilcoxon rank-sum test for continuous variables. PFS was analyzed using the Kaplan Meier method and Cox model was used to analyze factors associated with PFS.

Results: 344 pts who met eligibility criteria were included in the analysis. Pts receiving palbociclib on clinical trial were excluded. 109 (31.6%) pts received dose reductions and 153 (44.4%) experienced dose delays. The rate of neutropenic fever was low, occurring in 2.3% of all pts. There was a significant association between pts experiencing dose reductions and Hispanic race, baseline ANC, history of adjuvant endocrine therapy, adjuvant radiation therapy (XRT), and heart disease. History of adjuvant XRT, baseline ANC, and heart disease were associated with dose delays. Toxicities, including neutropenic fever, infections requiring antibiotics, and hospitalizations, were associated with dose reductions and dose delays. Median PFS for the cohort was 263.5 days. There was no significant association between early dose reductions or delays with PFS. Pts experiencing late dose delays (hazard ratio [HR], 0.4, P=0.0001) and reductions (HR, 0.4, P=0.0005) had a significantly longer PFS. Median PFS for pts without late dose delays was 228 days compared to 313.5 days for pts with late dose delays. Median PFS for pts without late dose reductions was 246 days compared to 305.5 days for pts with late dose reductions. In the multivariable analysis, liver metastasis, metastatic line, and higher tumor grade were associated with worse PFS. Pts receiving palbociclib and fulvestrant were found to have worse PFS than pts receiving palbociclib and letrozole.

Conclusions: Similar to the PALOMA trials, this study found that while the rate of toxicities such as neutropenic fever were low, dose reductions and delays were common. In pts receiving palbociclib as standard of care, pts with late dose reductions and delays had a longer PFS than those without dose reductions and delays. It is reassuring that the PFS was not negatively affected in pts with dose reductions and delays. As use of palbociclib as standard of care becomes more common, further larger retrospective studies are warranted to examine the impact of dose delays and reductions.

Citation Format: Clifton KK, Kimmel J, Yi M, Chad B, Litton J, Debu T, Meghan K. The impact of dose delays and reductions on toxicity and progression free survival (PFS) in patients receiving palbociclib [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-11-03.

Abstract P1-07-22: Androgen receptor positivity is associated with nodal disease in triple negative breast cancer

Background: Gene expression profiling (GEP) has identified several molecularly distinct subtypes of triple negative breast cancer (TNBC). Currently, GEP-based molecular diagnostics are not routinely used in clinical decision making due to the lack of proven benefit, costs involved and long turnaround time. However, two molecularly distinct subtypes of TNBC, the luminal androgen receptor (AR) and mesenchymal subtypes, have surrogate CLIA-certified immunohistochemical (IHC) markers, AR and vimentin (VM), respectively, which have the potential for application in the clinic. Here we report the rates of AR and VM positivity and their association with clinicopathological characteristics in a cohort of TNBC pts receiving NACT.

Methods: As part of an ongoing molecular triaging protocol, 144 pts with stage I-III TNBC underwent a pretreatment biopsy for molecular characterization (MC) prior to initiating neoadjuvant chemotherapy (NACT). IHC for AR and VM were performed using commercially available antibodies. AR+ and VM+ were defined as ≥10% and ≥50% staining, respectively. Pts were randomized 2:1 to know (intervention arm, n=93) and not know (control arm, n=51) the MC results. The charts of pts randomized to the intervention arm were reviewed. Categorical variables were analyzed using Fisher's exact test. Ordinal and continuous variables were analyzed using the Wilcoxon rank-sum test and Student's t test as appropriate.

Results: 31% (29/93) and 16% (15/93) of pts were AR+ and VM+, respectively. Only 4% (4/93) of pts were both AR+ and VM+. Clinicopathological characteristics are summarized in Table 1. AR+ pts were more likely to have clinically node positive disease as compared to AR- pts (66% vs 34%, p=0.007). There were no significant differences in clinical tumor size or grade between AR+ and AR- pts. VM+ and VM- pts had similar clinicopathological characteristics.

Conclusion: Pts with AR+ TNBC were more likely to have node positive disease. The impact of AR+ on long term outcomes should be investigated in prospective studies.

Table 1: Association between patient characteristics and AR/VM status AR  VM   AR+ (n=29)AR- (n=64)p-valueVM+ (n=15)VM- (n=78)p-valueAge - Median (years, interquartile range)58 (48-65)52 (46-61)0.05855 (48-64)56 (47-62)0.88Clinical Tumor Size      Mean (cm, standard deviation)3.5 (1.8)3.0 (1.8)0.2872.7 (1.7)3.3 (1.9)0.31T1 – n(%)5 (17)21 (33)0.2307 (47)19 (24)0.098T2 – n(%)21 (72)36 (56) 7 (47)50 (64) T3 – n(%)3 (10)7 (11) 1 (7)9 (12) Clinical Nodal Status      Negative – n(%)10 (34)42 (66)0.0078 (53)44 (56)1.00Positive – n(%)19 (66)22 (34) 7 (47)34 (44) Grade      2 – n(%)6 (21)5 (8)0.0763 (20)8 (10)0.293 – n(%)23 (79)59 (92) 12 (80)70 (90) 

Citation Format: Yam C, Huo L, Hess KR, Litton JK, Yang W, Piwnica-Worms H, Mittendorf EA, Ueno NT, Lim B, Murthy RK, Damodaran S, Helgason T, Thompson AM, Santiago L, Candelaria RP, Rauch GM, Adrada BE, Symmans WF, Gilcrease MZ, Moulder SL. Androgen receptor positivity is associated with nodal disease in triple negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-22.

A feasibility study of neoadjuvant talazoparib for operable breast cancer patients with a germline BRCA mutation demonstrates marked activity

This study was undertaken to determine the feasibility of enrolling breast cancer patients on a single-agent-targeted therapy trial before neoadjuvant chemotherapy. Specifically, we evaluated talazoparib in patients harboring a deleterious BRCA mutation (BRCA+). Patients with a germline BRCA mutation and ≥1 cm, HER2-negative primary tumors were eligible. Study participants underwent a pretreatment biopsy, 2 months of talazoparib, off-study core biopsy, anthracycline, and taxane-based chemotherapy ± carboplatin, followed by surgery. Volumetric changes in tumor size were determined by ultrasound at 1 and 2 months of therapy. Success was defined as 20 patients accrued within 2 years and <33% experienced a grade 4 toxicity. The study was stopped early after 13 patients (BRCA1 + n = 10; BRCA2 + n = 3) were accrued within 8 months with no grade 4 toxicities and only one patient requiring dose reduction due to grade 3 neutropenia. The median age was 40 years (range 25–55) and clinical stage included I (n = 2), II (n = 9), and III (n = 2). Most tumors (n = 9) were hormone receptor-negative, and one of these was metaplastic. Decreases in tumor volume occurred in all patients following 2 months of talazoparib; the median was 88% (range 30–98%). Common toxicities were neutropenia, anemia, thrombocytopenia, nausea, dizziness, and fatigue. Single-agent-targeted therapy trials are feasible in BRCA+ patients. Given the rapid rate of accrual, profound response and favorable toxicity profile, the feasibility study was modified into a phase II study to determine pathologic complete response rates after 4–6 months of single-agent talazoparib.

An investigational PARP inhibitor seems safe and possibly effective when given ahead of surgery to women with BRCA-mutated breast cancer. Jennifer Litton and colleagues from the University of Texas MD Anderson Cancer Center in Houston, USA, conducted a small feasibility study to see if patients with stage I-III breast cancer and inherited mutations in BRCA1 or BRCA2 would put off their standard course of chemotherapy ahead of surgery to first receive two months of talazoparib, an experimental inhibitor of poly ADP ribose polymerase (PARP), an enzyme involved in DNA damage repair. The trial was a resounding success. In fact, owing to rapid patient enrollment, decreases in tumor volume among all 13 participants and few signs of serious side effects, the researchers amended the study protocol to give talazoparib for longer and test for therapeutic efficacy.

Abstract OT2-01-22: NCT02456857: A phase II trial of liposomal doxorubicin, bevacizumab and everolimus (DAE) in patients (pts) with localized triple-negative breast cancer (TNBC) with tumors predicted insensitive to standard neoadjuvant chemotherapy (NACT)

BACKGROUND: Approximately 50% of TNBC pts treated with standard taxane/anthracycline-based NACT will have chemo-insensitive disease (CID) manifested as extensive residual disease (RCB-II or III) at the time of surgery. 40-80% of these pts will develop recurrence within 3 years of initial diagnosis. Recent advances in molecular profiling have identified subsets of TNBC with distinct, targetable molecular features. We developed a clinical trial to identify and characterize CID (ARTEMIS: A Randomized, TNBC Enrolling trial to confirm Molecular profiling Improves Survival). In the ARTEMIS trial, treatment naïve pts with localized TNBC undergo a pretreatment biopsy and then immediately start their initial phase of anthracycline-based chemotherapy so that the results of the molecular characterization are used in combination with response assessment (clinical exam/diagnostic imaging) to identify CID and inform the second phase of NACT, thus using a 'second hit' strategy in the middle of NACT to overcome drug resistance. The mesenchymal subtypes of TNBC have a high incidence of PI3K pathway activation. Preclinical models demonstrated response to PI3K inhibitors in this subtype. Metaplastic breast cancers make up ∼30% of tumors characterized as 'claudin-low/mesenchymal' by gene signature and are also associated with a high rate of PI3K activating molecular aberrations. A combination regimen of liposomal doxorubicin, bevacizumab and the mTOR inhibitors temsirolimus or everolimus (DAT or DAE) demonstrated response (including durable complete responses) in metastatic metaplastic breast cancer.

PRIMARY OBJECTIVE: Determine the rate of pathologic complete response (pCR/RCB-0) or minimal residual disease (RCB-I) after 4 cycles of DAE for treatment of mesenchymal TNBC deemed to be CID through the ARTEMIS trial

TRIAL DESIGN AND STATISTICAL METHODS: Only pts deemed to have mesenchymal CID on the ARTEMIS trial can enter this non-randomized phase II study. Realizing that pts without response to their initial cycles of chemotherapy have very low chance (5%) of achieving pCR with additional cycles of chemotherapy, it would be clinically meaningful to see pCR in this pt population improved to 20%. Counting pCR (RCB-0) or RCB-I as response, a two-stage Gehan-type design will be employed with 14 pts in the first stage. If at least one pt responds, 23 more pts will be added for a total of 37 pts. This design has a 49% chance of terminating after the first stage if the true response rate is 0.05, 23% chance if the true rate is 0.10, 10% if the true rate is 0.15 and 4% if the true rate is 0.20. If accrual continues to the second stage and a total of 37 pts are enrolled, the 95% confidence interval for a 0.20 response rate will extend from 0.10 to 0.35.

BRIEF ELIGIBILITY CRITERIA: Inclusion: localized TNBC enrolled onto ARTEMIS trial, adequate organ, bone marrow and cardiac parameters Exclusion: metastatic disease, pregnant or lactating pts, medical illness that increases chance of moderate to severe toxicity

CORRELATIVE SCIENCE: Correlate vimentin expression by IHC, mesenchymal signatures and PI3K pathway aberrations with response.

Citation Format: Moulder S, Hess K, Rauch M, Astrada B, Litton J, Mittendorf E, Ueno N, Tripathy D, Lim B, Piwnica-Worms H, Thompson A, Symmans WF. NCT02456857: A phase II trial of liposomal doxorubicin, bevacizumab and everolimus (DAE) in patients (pts) with localized triple-negative breast cancer (TNBC) with tumors predicted insensitive to standard neoadjuvant chemotherapy (NACT) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-22.

Abstract OT2-01-14: Triple-negative first-line study: Neoadjuvant trial of nab-paclitaxel and atezolizumab, a PD-L1 inhibitor, in patients with triple negative breast cancer (TNBC) (NCT02530489)

BACKGROUND: TNBC has an especially poor prognosis in patients (pts) whose tumor does not respond to anthracycline and taxane-based chemotherapy. Approximately 50% will have chemo-insensitive disease (CID) resulting in extensive residual disease at the time of surgery. 40-80% of these pts will recur &lt; 3 years. Recently developed molecular profiling techniques to identify TNBC subsets detect distinct molecular hallmarks. We designed a clinical trial to identify and characterize CID (ARTEMIS: A Randomized, TNBC Enrolling trial to confirm Molecular profiling Improves Survival). Treatment naïve pts with localized TNBC undergo a pretreatment biopsy followed by anthracycline-based chemotherapy (AC). During AC the molecular profile is determined; these results along with the response assessment (clinical exam/diagnostic imaging) will identify CID and guide the second phase of neoadjuvant chemotherapy. Tumor-infiltrating lymphocytes (TIL) have been identified as having prognostic and predictive significance in TNBC pts leading to higher pCR rates post NACT. However, the tumor microenvironment also contains regulatory T cells and myeloid-derived suppressor cells that are immunosuppressive. Programmed death ligand 1 (PD-L1) is expressed in 20% TNBC. Targeting this may lead to a more durable response as compared to chemotherapy alone.

PRIMARY OBJECTIVE: Evaluate the rate of pathologic complete response (pCR)/RCB-0 + residual cancer burden (RCB)-I responses in TNBC pts, determined to have CID after anthracycline-based chemotherapy, then treat with atezolizumab + nab-paclitaxel preoperatively.

TRIAL DESIGN AND STATISITCAL METHODS: Pts deemed to have CID on the ARTEMIS trial can enter this non-randomized phase II study. Pts without response to their initial chemotherapy cycles have a low likelihood (5%) of achieving pCR with additional cycles of chemotherapy. It would be clinically meaningful for pCR to improve to 20%. Counting pCR (RCB-0) or RCB-I as response given similar survival outcomes, a two-stage Gehan-type design will be employed with 14 pts in the first stage. If at least one pt responds, 23 more will be added. This design has a 49% chance of terminating after the first stage if the true response rate is 0.05, 23% chance if the true rate is 0.10, 10% if the true rate is 0.15 and 4% if the true rate is 0.20. If accrual continues to the second stage, the 95% confidence interval for a 0.20 response rate will extend from 0.10 to 0.35.

BRIEF ELIGIBILITY CRITERIA: Inclusion: localized TNBC enrolled onto ARTEMIS and determined to have CID at the time of response assessment after anthracycline chemotherapy, adequate organ, bone marrow and cardiac parameters. Exclusion: prior immunotherapy, IBC, history of autoimmune disease, HIV, Hep-B, Hep-C, active tuberculosis, pregnant.

CORRELATIVE SCIENCE: Evaluate the presence and phenotype of TIL and other immune cell populations in tumor tissue pre/post treatment; determine changes in expression of co-stimulatory and co-inhibitory molecules on tumor cells and immune cells in the microenvironment; evaluate the immune repertoire and cytokine responses in serially collected peripheral blood mononuclear cells and serum respectively.

Citation Format: Litton JK, Moulder S, Helgason T, Clayborn AR, Rauch GM, Gilcrease M, Adrada BE, Huo L, Hess KR, Symmans WF, Thompson A, Tripathy D, Mittendorf EA. Triple-negative first-line study: Neoadjuvant trial of nab-paclitaxel and atezolizumab, a PD-L1 inhibitor, in patients with triple negative breast cancer (TNBC) (NCT02530489) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-14.

Abstract P2-07-09: CPM rate among individuals with breast cancer who underwent multiplex gene testing for hereditary cancer: Single institution experience

Background: Availability of multiplex gene (MPG) testing for hereditary cancer has led to increase use of panel testing versus single gene testing for hereditary cancer. These panels include high, but also moderate penetrance genes. For some of these genes, associated cancer risk and risk management guidelines do not exist. Furthermore there is a high rate of variant of unknown significant (VUS) findings in non-BRCA genes. Currently, in the absence or minimal available data, health care providers and patients are faced with important risk management decisions, especially regarding preventive surgeries, such as prophylactic mastectomy. Currently, there is no data regarding prophylactic mastectomy rate among patients with breast cancer who underwent (MPG) testing. Therefore, our aim was to evaluate the rate of contralateral prophylactic mastectomy (CPM) in a cohort of individuals who underwent multiplex gene testing. Methods: Eight hundred thirty five patients with breast cancer who underwent MPG testing between the years 2013 and 2016 were identified using Institutional Clinical Cancer Genetics Database. Patients with pathogenic, likely pathogenic variants or who had a VUS were included in the analysis. Results: Of 835 patients with a diagnosis of breast cancer; 105 (13%) had a pathogenic or likely pathogenic mutation: 29 (28%) BRCA1, 26 (25%) BRCA2, 11 (11%) ATM, 2 (2%) BARD1, 3 (3%) BRIP, 9 (9%) CHEK2, 1 (1%) MSH2, 1 (1%) NBN, 5 (5%) PALB2, 4 (4%) PTEN, 1 (1%) RAD51C, 5 (5%) TP53, 4 (4%) CDH1, 2 (2%) MUTYH, 1 (1%) PMS2, 1 (1%) APC (1). A total of 102 (12%) VUS were found. Average age of diagnosis was 44 (Range 21-81). CPM rate was 32% (n=66) for the total cohort. Twenty nine % (n=19) of patients with non-BRCA mutations, 24.2% (n=16) with VUS and 46% (n=31) with BRCA mutations opted for CPM. Conclusion: Overall 32% of breast cancer patients with germline mutations or VUS opt for CPM at our institution. The rate for CPM in non- BRCA mutations carriers is high despite no available data regarding contralateral breast cancer risk and benefit of CPM. This finding should be validated in larger cohorts, including identification of reasons behind decision for CPM in these cohorts.

Citation Format: Elsayegh N, Gutierrez Barrera AM, Kuerer HM, Hernandez ND, Litton JK, Arun BK. CPM rate among individuals with breast cancer who underwent multiplex gene testing for hereditary cancer: Single institution experience [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-07-09.

Abstract OT2-01-13: A phase 3, open-label, randomized, 2-arm international study of the oral dual PARP inhibitor talazoparib in germline BRCA mutation subjects with locally advanced and/or metastatic breast cancer (EMBRACA)

Background: Cancer cells with deleterious mutations in breast cancer susceptibility genes 1 and 2 (BRCA1/2) are deficient in the DNA double-strand break repair mechanism, rendering them highly dependent on the single-strand break repair pathway, regulated by poly(ADP-ribose) polymerase (PARP). Inhibition of PARP results in synthetic lethality in cells with a BRCA1/2 mutation because of accumulation of irreparable DNA damage; PARP inhibitors have the potential to be selectively toxic for BRCA-mutated cells. In addition to catalytic inhibition, it has been shown that some PARP inhibitors induce PARP trapping at sites of DNA damage. The capacity to trap PARP-DNA complexes varies widely across different PARP inhibitors and is not correlated with PARP catalytic inhibition. Preclinical models have shown trapping PARP on DNA is more potent at inducing cancer cell death than enzymatic inhibition of PARP alone. Talazoparib is a dual-mechanism PARP inhibitor that both inhibits the PARP enzyme and effectively traps PARP on DNA, preventing DNA damage repair and resulting in cell death in BRCA1/2-mutated cells. In preclinical studies, talazoparib at nanomolar concentrations showed the highest efficiency at trapping PARP-DNA complexes relative to other PARP inhibitors. In a previous phase 1/2 clinical study, talazoparib as monotherapy (1 mg once daily) resulted in a 50% response rate and an 86% clinical benefit rate at 24 weeks in 14 patients with a germline BRCA1/2 mutation and advanced breast cancer (aBC).

Methods: This open-label, randomized, 2-arm, international phase 3 trial (EMBRACA)

compares the efficacy and safety of talazoparib with protocol-specific physician's choice (capecitabine, eribulin, gemcitabine or vinorelbine) in patients with aBC. The primary objective is progression-free survival by central imaging. Secondary objectives are objective response rate, overall survival, safety and pharmacokinetics of talazoparib. Exploratory objectives include health-related quality of life measurements and biomarker research in blood and tumor samples that may permit characterization of mechanisms involved in tumor sensitivity and resistance to talazoparib. Key patient eligibility criteria include aged ≥18 years with histologically/cytologically confirmed breast cancer; locally advanced and/or metastatic disease appropriate for systemic single-agent cytotoxic chemotherapy; deleterious or pathogenic germline BRCA1/2 mutations by central laboratory; ≤3 prior cytotoxic chemotherapy regimens for advanced disease (prior platinum is allowed provided patients did not relapse within 6 months in the adjuvant setting or did not progress on platinum therapy); prior treatment with a taxane and/or anthracycline unless medically contraindicated; and ECOG performance status ≤2. Patients (N=429) will be randomized 2:1 to receive either talazoparib capsules (1 mg/day, 21-day cycles) or physician's choice treatment. This trial is currently enrolling patients from the USA, Europe, Israel, Ukraine, Russia, Korea, Australia, Taiwan and Brazil (NCT01945775).

This study is funded by Medivation, Inc.

Citation Format: Litton J, Ettl J, Hurvitz SA, Mina LA, Rugo HS, Lee K-H, Yerushalmi R, Woodward N, Goncalves A, Moreno F, Roche H, Im Y-H, Martin M, Bhattacharya S, Peterson A, Hannah A, Eiermann W, Blum J. A phase 3, open-label, randomized, 2-arm international study of the oral dual PARP inhibitor talazoparib in germline BRCA mutation subjects with locally advanced and/or metastatic breast cancer (EMBRACA) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-13.

Abstract OT3-02-05: NCI-2016-00367: A phase IIB study of neoadjuvant ZT regimen (enzalutamide therapy in combination with weekly paclitaxel) for androgen receptor (AR)-positive triple-negative breast cancer (TNBC)

BACKGROUND: Approximately 50% of TNBC expresses AR by immunohistochemical (IHC) staining. Luminal androgen receptor (LAR) subtype is heavily enriched in hormonally regulated genes, yet negative for ER by IHC. LAR is associated with low pCR rates and long survival. Preclinical data have shown that taxanes inhibit translocation of AR from the cytoplasm to the nucleus where AR is activated. Combining paclitaxel with enzalutamide may inhibit the AR pathway synergistically thereby increasing pCR rates. We hypothesized that patients with AR-positive TNBC who have chemo-insensitive disease (CID) after initial anthracycline-based chemotherapy treated with ZT would have higher RCB-0 and RCB-I rates than those who receive conventional taxane-based chemotherapy. Our team developed a clinical trial to identify patients with CID (ARTEMIS: A Randomized, TNBC Enrolling trial to confirm Molecular profiling Improves Survival). In the ARTEMIS trial, treatment-naïve patients with localized TNBC undergo a pretreatment biopsy and then begin anthracycline-based chemotherapy. Molecular testing results and radiographic response assessment are used to identify CID and will guide the second phase of neoadjuvant chemotherapy (NACT) to overcome CID.

PRIMARY OBJECTIVE: To determine RCB-0 and RCB-I rates of patients with TNBC who have CID to initial anthracycline-based chemotherapy and who received ZT.

TRIAL DESIGN AND STATISTICAL METHODS: Patients with CID from the ARTEMIS trial can enroll in the 12-week ZT (paclitaxel, 80 mg/m2 intravenously per week; enzalutamide, 160 mg orally per day). We will define pCR (RCB-0) or RCB-I as a response, using a Simon optimal 2-stage design with alpha=beta=10% and then setting the threshold for an acceptable pCR or RCB-I rate at 20%. We will enroll 12 patients into the first stage. If no patients experience pCR or RCB-I, we will stop the study after the first stage. If at least 1 patient experiences pCR or RCB-I, we will enroll 25 more patients for a total of 37 patients. We would declare the treatment worthy of further study if at least 4 of the 37 patients experience pCR or RCB-I. This design has a 54% probability of early termination after the first stage if the true pCR or RCB-I probability is 5%. Because patients with CID have a very low chance (5%) of achieving pCR with additional chemotherapy, improving pCR rates to 20% in this patient population would be clinically meaningful.

BRIEF ELIGIBILITY CRITERIA: Inclusion criteria: Primary invasive TNBC patients who have CID under the ARTEMIS trial; AR+ ≥1% nuclear staining by IHC; and adequate physical, organ, bone marrow, and cardiac functions. Exclusion criteria: Pregnant or lactating patients, history of colitis or absorption abnormality, known or suspected brain metastasis or leptomeningeal disease, or history of seizure.

CORRELATIVE SCIENCE: Enumeration of circulating tumor cells (CTCs) and expression of CTC-related gene transcripts will be measured to correlate CTC characteristics and/or gene profiles related to the AR pathway and treatment response to ZT.

Citation Format: Fujii T, Lim B, Helgason T, Hess KR, Gilcrease MZ, Willey JS, Tripathy D, Litton JK, Moulder S, Krishnamurthy S, Yang W, Reuben JM, Symmans WF, Ueno NT. NCI-2016-00367: A phase IIB study of neoadjuvant ZT regimen (enzalutamide therapy in combination with weekly paclitaxel) for androgen receptor (AR)-positive triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-02-05.

Primary analysis of a prospective, randomized, single-blinded phase II trial evaluating the HER2 peptide AE37 vaccine in breast cancer patients to prevent recurrence

BACKGROUND

AE37 is the Ii-Key hybrid of the MHC class II peptide, AE36 (HER2 aa:776-790). Phase I studies showed AE37 administered with granulocyte macrophage colony-stimulating factor (GM-CSF) to be safe and highly immunogenic. A prospective, randomized, multicenter phase II adjuvant trial was conducted to evaluate the vaccine's efficacy.

METHODS

Clinically disease-free node-positive and high-risk node-negative breast cancer patients with tumors expressing any degree of HER2 [immunohistochemistry (IHC) 1-3+] were enrolled. Patients were randomized to AE37 + GM-CSF versus GM-CSF alone. Toxicity was monitored. Clinical recurrences were documented and disease-free survival (DFS) analyzed.

RESULTS

The trial enrolled 298 patients; 153 received AE37 + GM-CSF and 145 received GM-CSF alone. The groups were well matched for clinicopathologic characteristics. Toxicities have been minimal. At the time of the primary analysis, the recurrence rate in the vaccinated group was 12.4% versus 13.8% in the control group [relative risk reduction 12%, HR 0.885, 95% confidence interval (CI) 0.472-1.659, P = 0.70]. The Kaplan-Meier estimated 5-year DFS rate was 80.8% in vaccinated versus 79.5% in control patients. In planned subset analyses of patients with IHC 1+/2+ HER2-expressing tumors, 5-year DFS was 77.2% in vaccinated patients (n = 76) versus 65.7% in control patients (n = 78) (P = 0.21). In patients with triple-negative breast cancer (HER2 IHC 1+/2+ and hormone receptor negative) DFS was 77.7% in vaccinated patients (n = 25) versus 49.0% in control patients (n = 25) (P = 0.12).

CONCLUSION

The overall intention-to-treat analysis demonstrates no benefit to vaccination. However, the results confirm that the vaccine is safe and suggest that vaccination may have clinical benefit in patients with low HER2-expressing tumors, specifically TNBC. Further evaluation in a randomized trial enrolling TNBC patients is warranted.

Abstract P1-14-04: A randomized phase II neoadjuvant (NACT) study of sequential eribulin followed by FAC/FEC-regimen compared to sequential paclitaxel followed by FAC/FEC-regimen in patients (pts) with operable breast cancer not overexpressing HER-2

Background: Neoadjuvant chemotherapy (NACT) is an integral component for locally advanced and large operable breast cancer. The sequence of taxanes followed by anthracyclines has been the standard of care for almost 20 years. Eribulin (E) is a synthetic analogue of halichondrin B with distinct mechanism of action as microtubule dynamics inhibitor. The FDA approved E in 11/2010 for the treatment of patients (pts) with metastatic breast cancer who have previously received at least two chemotherapeutic regimens for the treatment of metastatic disease. Research Hypothesis: Sequential administration of eribulin followed by FAC/FEC-regimen, would have greater pathologic complete response (pCR) rate than sequential administration of paclitaxel followed by FAC/FEC-regimen as primary systemic therapy for woman with operable breast cancer.

Methods: This is a phase II, randomized, single institution, open label study. Pts were randomized 1:1 to receive E (1.4 mg/m2 d1 and d8 q 21 days x 4) or paclitaxel (P) (80 mg/m2 weekly x12). Both arms received FAC/FEC regimen x 4 doses followed by surgery. Eligible pts were women age 18 or older, Karnosfky PS 80 – 100, histologically confirmed invasive breast cancer, clinical T2-T3, N0-3, M0, HER2-negative. Baseline LVEF of &gt; 50% and normal hematology, liver and kidney laboratory function tests. Primary endpoint was pathologic complete response (pCR/RCB-0) assessed by residual cancer burden (RCB). [Symmans F, 2007]. This protocol (2012-0167) IRB of The University of Texas, MD Anderson Cancer Center.

Results: A preplanned interim analysis aimed to validate trial assumption was conducted after treatment of 54 randomized pts. Between 8/2012 to 7/2014, 54 pts were randomized and 49 were evaluable for pCR(27 P arm and 22 E arm). Tumor response by RCB is shown in the table. pCR rates were 30% and 4.5% in the P and E arm, respectively.

Table 1.ResponsePaclitaxel - FAC/FEC Arm (N=27)Eribulin - FAC/FEC Arm (N=22)RCB 0 (pCR)8 (30%)1 (4.5%)RCB I6 (22.2%)1 (4.5%)RCB II9 (33%)10 (45%)RCB III4 (14.8%)10 (45%)

53 pts were evaluable for toxicity. The combination was safe with mostly grade 1 and 2 toxicities in both arms. In the P arm grade 3 peripheral neuropathy and neutropenia was seen in 3% and 7%, respectively. In the E arm one patient died due to multiorgan failure during cycle 1. There was no other grade 3-5 toxicity. Biomarker analysis using CTCs by AdnaTest Breast were evaluated in 39 pts at baseline. 5/39 pts were positive for CTCs. 3 pts had transcripts for EpCAM, 1 for Muc-1 and another had both. 30 pts had an additional sample post therapy. 2 pts were positive for CTC at baseline as well as at follow up (FU) visit at 180 days. None of the samples showed CTC-EMT at baseline or at FU visits.

Conclusions: The interim analysis demonstrated that E arm lead to significantly lower pCR/RCB1 rate compared to P arm. Ongoing biomarker analyses include TIL, hot spot mutation analysis (HSMA) and molecular inversion probes (MIP) will be presented at the time of the meeting. Clinical trial information: NCT01593020.

Citation Format: Alvarez RH, Koenig KB, Ensor JE, Ibrahim NK, Chavez-MacGregor M, Litton JK, Schwartz Gomez JK, Cyriac A, Krishnamurty S, Caudle AS, Shaitelman SF, Whitman GJ, Booser DJ, Reuben JM, Valero V. A randomized phase II neoadjuvant (NACT) study of sequential eribulin followed by FAC/FEC-regimen compared to sequential paclitaxel followed by FAC/FEC-regimen in patients (pts) with operable breast cancer not overexpressing HER-2. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-04.

Abstract P1-14-07: Association between quantitative values of estrogen receptor expression level and pathological complete response in human epidermal growth factor 2-negative breast cancer: Should the clinical definition of triple-negative breast cancer be redefined?

Background: The American Society of Clinical Oncology/College of American Pathologists recommended that the cut-off for negative status of estrogen receptor (ER) should be &lt;1% positively staining cells, although a 10% cut-off has often been used clinically. Prior studies reported that patients with ER ranging from 1% to 9% showed survival outcomes and molecular features similar to those of patients with ER positivity of &lt;1%; however, those studies did not take into account patients' human epidermal growth factor 2 (HER2) status. This means we have yet to clarify the exact clinical definition of triple-negative breast cancer (TNBC) on the basis of response to preoperative chemotherapy. Previous studies reported that hormone receptor–positive tumors were less sensitive to systemic chemotherapies. On the basis of these facts, we hypothesized that in patients with HER2-negative breast cancer ER expression level as a continuous variable has an inverse linear association with pathological complete response (pCR) rate. Our primary objective was to determine whether a quantitative value of ER between 0% and 10% is predictive of pCR rate in HER2-negative patients treated with neoadjuvant chemotherapy. Secondary objective was to find the ideal cut-off value of ER expression.

Methods: We included newly diagnosed stage I-III HER2-negative breast cancer patients with available ER (0%≤ER&lt;10%) who were treated with neoadjuvant systemic chemotherapy. ER status was determined by immunohistochemical (IHC) staining; HER2 status was determined by IHC and/or FISH. We used univariate and multivariate logistic regression models to determine the association between baseline variables and pCR. A backward stepwise method was used to select the covariates for the multivariate analysis. Recursive partitioning and regression tree method were used to identify the potential significant cut-off of ER.

Results: The analysis included 1155 patients with newly diagnosed HER2-negative invasive breast cancer. The univariate logistic regression analysis showed that ER as a continuous variable was not a statistically significant factor for predicting pCR (ER: OR=0.98, 95%CI: 0.9-1.07, P=0.68). In the multivariate analysis, ER status again was not a significant factor for predicting pCR (OR=0.97, 95%CI 0.9-1.06, P=0.55). ER as a categorical variable, there was no significant difference of the pCR rate between 0&lt;ER&lt;1 and 1≤ER&lt;10 groups (OR=1.27, 95%CI: 0.62-2.62, P=0.52). Among ER&gt; 0 (n=229), the recommended cut-off value of ER was 5.5. However, the odds ratio of pCR rate divided by this value of 5.5 was not significant (ER≤5 vs ER&gt;5; OR 1.94 95%CI 0.54-6.95 P=0.31).

Conclusion: Evaluating ER (&lt;10%) as a continuous variable showed no association with pCR rate, and no cut-off of ER was identified with which to stratify patients into groups more or less likely to achieve pCR. A potential meaningful cut-off ER value might exist between 10% and 100% in HER2-negative patients. We will explore whether a meaningful cut-off ER value exists that will change the pCR rate and possibly lead to redefining the clinical definition of TNBC.

Citation Format: Fujii T, Kogawa T, Dong W, Moulder S, Litton JK, Tripathy D, Lim B, Shen Y, Ueno NT. Association between quantitative values of estrogen receptor expression level and pathological complete response in human epidermal growth factor 2-negative breast cancer: Should the clinical definition of triple-negative breast cancer be redefined?. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-14-07.

Abstract OT2-03-03: Women's triple-negative, first-line treatment: Improving outcomes in triple-negative breast cancer using molecular triaging and diagnostic imaging to guide neoadjuvant therapy

BACKGROUND:

In triple negative breast cancer (TNBC), pathologic compete response/residual cancer burden-0 (pCR/RCB-0) or minimal residual disease (RCB-I) following neoadjuvant chemotherapy (NACT) is associated with a good prognosis. This is in contrast to extensive residual disease (RCB-II-III) which carries approximately a 50% chance of recurrence. These patients have a particularly poor prognosis as there are currently no targeted agents to salvage chemoresistant disease. It is important to predict pCR in order to direct responsive disease toward standard NACT and non-responsive disease (NRD) to therapy on clinical trials.

TRIAL DESIGN:

The use of genomic signatures (JAMA, 2011; 305:1873-81) and imaging to predict response to NACT will be validated, and the clinical impact of selecting patients with predicted NRD for targeted therapy on clinical trial will be determined. Patients will undergo primary tumor biopsy for molecular profiling and will be randomized 2:1 to know the results versus not (control). Following that, all patients will receive 4 cycles of anthracycline-based NACT, with imaging used for response assessment. Patients with molecular/imaging criteria for NRD will be offered enrollment on a clinical trial based upon molecular profiling or based upon physician/patient choice (control).

INCLUSION CRITERIA:

Tumor size ≥1.5 cm diameter; TNBC by standard assays; ≥18 years of age; LVEF ≥50%; adequate organ and bone marrow function

EXCLUSION CRITERIA:

Stage IV disease; invasive cancer within 5 years; excisional biopsy of the primary tumor; features that limit response assessment by imaging; unfit for taxane and/or antracycline regimens; prior anthracycline therapy; ≥grade II neuropathy; Zubrod performance status of ≥2; history of serious cardiac events

PRIMARY AIM:

- Prospectively determine the impact of a molecular diagnostic/imaging platform in patients with localized invasive TNBC

SECONDARY AIMS:

- Compare rates of clinical trial enrollment

- Evaluate disease free survival in the experimental arms compared to control standard NACT

- Perform integrated biomarker analyses and identify therapeutic targets for resistant disease

STATISTICAL METHODS:

A maximum of 360 patients will be randomized (2:1)using a group sequential design with one-sided O'Brien-Fleming boundaries, with two equally spaced binding interim tests for futility and superiority and one final test, having an overall Type I error .05 and power .80 to detect an improvement in pCR/RCB-I from 50% to 64%.

Citation Format: Mitri ZI, Ueno NT, Yang W, Valero V, Litton JK, Murthy RK, Ibrahim NK, Arun BK, Mittendorf EA, Hunt KK, Meric-Bernstam F, Thompson A, Piwnica-Worms H, Tripathy D, Symmans F, Moulder-Thompson S. Women's triple-negative, first-line treatment: Improving outcomes in triple-negative breast cancer using molecular triaging and diagnostic imaging to guide neoadjuvant therapy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT2-03-03.

Abstract P2-09-08: Universal BRCA testing and family outreach for women with triple negative breast cancer

Background Germline mutations in BRCA1 or BRCA2 significantly increase the lifetime risk for a woman to develop breast and ovarian cancers. Triple negative breast cancer (TNBC) is enriched for BRCA mutations, with approximately 20% of unselected TNBC patients having a BRCA1 or BRCA2 mutation. Current guidelines recommend individuals with TNBC age 60 or younger undergo BRCA genetic testing. Studies suggest that expanding testing beyond age 60 may capture additional BRCA positive women. Identification of a BRCA mutation has significant implications for early cancer detection and prevention, treatment options, and at-risk blood relatives. Many at-risk relatives are not aware of, or pursue genetic testing for mutations identified in their family. Our previous prediction models have shown that testing all at-risk first degree relatives of TNBC patients may reduce the risk of breast and ovarian cancers by 23%, and 41%. Few studies exist regarding the occurrence or success of intra-family cascade genetic testing. Study Design This study is conducted through the University of Texas MD Anderson Cancer Center's Women's Cancer Moonshot program. This is a five year prospective cohort study of unselected women with confirmed TNBC. It provides universal BRCA genetic testing for TNBC patients. TNBC patients are enrolled in a research registry which provides clinical BRCA genetic testing regardless of age of diagnosis. BRCA positive TNBC patients are consented for a separate prospective family outreach protocol (REACH registry). The REACH registry includes questionnaires and active outreach to at-risk family members using an innovative information-technology platform and a variety of web-based patient education tools. Results In year one of our study, a total of 439 patients with TNBC have been seen for genetic counseling and 377 (86%) have undergone BRCA genetic testing. Fifty-one (14%) patients were identified as having a BRCA mutation. Of those with a BRCA mutation, 48 (94%) have a BRCA1 mutation, 3 (6%) have a BRCA2 mutation and 1 (2%) would not have been identified by current testing guidelines. Further, 74 patients with identified BRCA mutations and 50 at-risk family members have enrolled in the REACH registry. Recruitment and data collection of patients and family members, and their communication, genetic testing, cancer risk reduction, and surgical choices are on-going. Using our innovative IT platform to collect information and to communicate with patients and families, we anticipate an increased study recruitment, patient and family participation, and ultimately improved awareness, education, and cancer-prevention and screening among our patients and their family members. Conclusion Through this study we have maximized awareness and identification of high-risk hereditary cancer patients through implementation of universal BRCA1 and BRCA2 genetic testing of all TNBC patients. We have shown initial feasibility to successfully recruit family members to our REACH registry. REACH registry is an innovative research platform providing education and awareness to patients and at-risk family members to aid communication and dissemination of BRCA test results and to assess the psychosocial and behavioral impacts of a mutation in a family.

Citation Format: Emborgo T, Muse KI, Bednar E, Oakley HD, Litton J, Lu KH, Arun BK. Universal BRCA testing and family outreach for women with triple negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-09-08.

Abstract P3-14-02: Targeting the PI3K/AKT/mTOR pathway for the treatment of mesenchymal triple-negative breast cancer (TNBC): Evidence of efficacy and proof of concept from a phase I trial with dose expansion of mTOR inhibition in combination with liposomal doxorubicin and bevacizumab

Background: Approximately 30% of TNBCs are characterized by microarray as claudin-low, mesenchymal or mesenchymal stem cell-like and, unlike basal TNBCs, these tumors frequently harbor aberrations in the PI3K/AKT/mTOR axis, raising the possibility of targeting this axis to enhance chemotherapy response. Assays to clinically identify mesenchymal TNBCs are under development, but published results confirm that up to 30% are metaplastic breast cancers (MpBCs), a chemo-refractory group of tumors that contain a mixture of epithelial and mesenchymal components, making them identifiable by microscopy. As such, MpBCs serve as surrogates of response for potential regimens to treat mesenchymal TNBC.

Methods: Patients (pts) with advanced TNBC (N=64) were treated with liposomal doxorubicin (D), bevacizumab (A) and the mTOR inhibitors temsirolimus (T) or everolimus (E). D and A were administered IV on day 1 with T (IV on days 1, 8 and 15) or E (continuous daily oral administration) using 21 day cycles. Response was assessed every 6 weeks using RECIST. When available, archived tissue was evaluated for aberrations in the PI3K pathway using standard assays.

Results: Fifty-two MpBC pts were treated with DAT (N=39) or DAE (N=13). Median age was 58 (range 37-79); median # of prior regimens for metastatic disease was 1 (range 0-5). The objective response rate (ORR) was 21% [complete response (CR)=4 (8%); partial response (PR)=7 (13%)] and 10 (19%) pts had stable disease (SD)≥6 months for a clinical benefit rate (CBR) of 40%. Tissue was available for testing in 43 pts and 32 (74%) had a PI3K pathway activating aberration (Table 1).

Response According to PI3K Pathway AberrationPI3K Pathway AberrationN (%)CRPRSD≥6monthsCBRORRAny PI3K Pathway Aberration*32 (74)46444%31%PIK3CA Mutation19 (59)23447%26%p.H1047R12 (38)21350%25%p.E545K6 (19)02150%33%p.G1007R1 (3)010100%100%p.E545A1 (3)0000%0%p.H1047Y1 (3)0000%0%p.K111E1 (3)0000%0%p.E542K1 (3)0000%0%PIK3CA Amplification1 (3)010100%100%PTEN Mutation5 (16)0000%0%PTEN Loss5 (16)02040%40%AKT1 p.E17K Mutation2 (6)0000%0%AKT2 Amplification1 (3)100100%100%PIK3R1 Mutation2 (6)01050%50%NF2 Mutation1 (3)100100%100%No PI3K Pathway Aberration11 (26)00545%0%*Some tumors had &gt;1 aberration detected

PI3K pathway activation was associated with a significant improvement in ORR (31 vs 0%; P=0.043) but not CBR (44 vs 45%; P=1.000) or progression-free survival (median 5.1 vs 2.9 months; P=0.352). A pt with 5 year+ durable CR (on maintenance everolimus) had a mutation in NF2. To emphasize the importance of pt selection, it is notable that 12 pts with non-metaplastic TNBC were also treated with DAT, and only 1 pt had a response (CR/PR=1; SD≥6 months=0), for a CBR that was significantly worse than pts with MpBC (8 vs 40%; P=0.045).

Conclusions: Using MpBC as a surrogate of response, DAT/DAE has significantly better activity in mesenchymal compared to non-selected TNBC. Response is enhanced in pts with PI3K pathway activation. DAT/DAE should be tested in non-metaplastic, mesenchymal TNBC once a diagnostic assay is available.

Citation Format: Basho RK, Gilcrease M, Murthy RK, Helgason T, Booser DJ, Karp DD, Meric-Bernstam F, Wheler JJ, Valero V, Albarracin C, Litton J, Chavez-MacGregor M, Ibrahim NK, Murray JL, Koenig KB, Hong D, Subbiah V, Kurzrock R, Janku F, Moulder S. Targeting the PI3K/AKT/mTOR pathway for the treatment of mesenchymal triple-negative breast cancer (TNBC): Evidence of efficacy and proof of concept from a phase I trial with dose expansion of mTOR inhibition in combination with liposomal doxorubicin and bevacizumab. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-14-02.

Incidental germline variants in 1000 advanced cancers on a prospective somatic genomic profiling protocol

BACKGROUND

Next-generation sequencing in cancer research may reveal germline variants of clinical significance. We report patient preferences for return of results and the prevalence of incidental pathogenic germline variants (PGVs).

PATIENTS AND METHODS

Targeted exome sequencing of 202 genes was carried out in 1000 advanced cancers using tumor and normal DNA in a research laboratory. Pathogenic variants in 18 genes, recommended for return by The American College of Medical Genetics and Genomics, as well as PALB2, were considered actionable. Patient preferences of return of incidental germline results were collected. Return of results was initiated with genetic counseling and repeat CLIA testing.

RESULTS

Of the 1000 patients who underwent sequencing, 43 had likely PGVs: APC (1), BRCA1 (11), BRCA2 (10), TP53 (10), MSH2 (1), MSH6 (4), PALB2 (2), PTEN (2), TSC2 (1), and RB1 (1). Twenty (47%) of 43 variants were previously known based on clinical genetic testing. Of the 1167 patients who consented for a germline testing protocol, 1157 (99%) desired to be informed of incidental results. Twenty-three previously unrecognized mutations identified in the research environment were confirmed with an orthogonal CLIA platform. All patients approached decided to proceed with formal genetic counseling; in all cases where formal genetic testing was carried out, the germline variant of concern validated with clinical genetic testing.

CONCLUSIONS

In this series, 2.3% patients had previously unrecognized pathogenic germline mutations in 19 cancer-related genes. Thus, genomic sequencing must be accompanied by a plan for return of germline results, in partnership with genetic counseling.

Open-label randomized clinical trial of standard neoadjuvant chemotherapy with paclitaxel followed by FEC versus the combination of paclitaxel and everolimus followed by FEC in women with triple receptor-negative breast cancer†

BACKGROUND

Everolimus synergistically enhances taxane-induced cytotoxicity in breast cancer cells in vitro and in vivo in addition to demonstrating a direct antiproliferative activity. We aim to determine pharmacodynamics changes and response of adding everolimus to standard neoadjuvant chemotherapy in triple-negative breast cancer (TNBC).

PATIENTS AND METHODS

Phase II study in patients with primary TNBC randomized to T-FEC (paclitaxel 80 mg/m(2) i.v. weekly for 12 weeks, followed by 5-fluorouracil 500 mg/m(2), epirubicin 100 mg/m(2), and cyclophosphamide 500 mg/m(2) every 3 weeks for four cycles) versus TR-FEC (paclitaxel 80 mg/m(2) i.v. and everolimus 30 mg PO weekly for 12 weeks, followed by FEC). Tumor samples were collected to assess molecular changes in the PI3K/AKT/mTOR pathway, at baseline, 48 h, 12 weeks, and at surgery by reverse phase protein arrays (RPPA). Clinical end points included 12-week clinical response rate (12-week RR), pathological complete response (pCR), and toxicity.

RESULTS

Sixty-two patients were registered, and 50 were randomized, 27 received T-FEC, and 23 received TR-FEC. Median age was 48 (range 31-75). There was downregulation of the mTOR pathway at 48 h in the TR-FEC arm. Twelve-week RR by ultrasound were 29.6% versus 47.8%, (P = 0.075), and pCR were 25.9% versus 30.4% (P = 0.76) for T-FEC and TR-FEC, respectively. mTOR downregulation at 48 h did not correlate with 12-week RR in the TR-FEC group (P = 0.58). Main NCI grade 3/4 toxicities included anemia, neutropenia, rash/desquamation, and vomiting in both arms. There was one case of grade 3 pneumonitis in the TR-FEC arm. No grade 3/4 stomatitis occurred.

CONCLUSION

The addition of everolimus to paclitaxel was well tolerated. Everolimus downregulated mTOR signaling but downregulation of mTOR at 48 h did not correlate with 12-week RR in the TR-FEC group.

CLINICAL TRIAL NUMBER

NCT00499603.

Abstract P4-12-18: BOLERO-3: Quality-of-life maintained in patients with metastatic breast cancer treated with everolimus plus trastuzumab plus vinorelbine

Background: Activation of the PI3K/mTOR pathway is implicated in resistance to trastuzumab. Accordingly, the BOLERO-3 study evaluated the efficacy of adding everolimus (EVE), an mTOR inhibitor, to vinorelbine and trastuzumab. At the final progression-free survival (PFS) analysis, EVE significantly improved PFS vs PBO (hazard ratio [HR] = 0.78; log-rank P = .0067) but EVE-treated patients had higher rate of grade 3/4 toxicity. To further qualify the benefit:risk of adding EVE to trastuzumab-based therapy, per-protocol, patient-reported, health-related quality-of-life (HRQoL) data were analyzed.

Methods: BOLERO-3 is a randomized phase 3, double-blind, placebo-controlled, international multicenter trial. Taxane-pretreated patients (N = 569) with trastuzumab-resistant, HER2+, advanced breast cancer were randomized (1:1) to treatment with EVE or placebo (PBO) plus vinorelbine and trastuzumab. The European Organisation for Research and Treatment of Cancer (EORTC) quality-of-life questionnaire C30 (QLQ-C30) (including the breast cancer-specific BR23 module) was administered at baseline and every 6 weeks thereafter until progression. The QLQ-C30 consists of 30 items combined into 15 subscales, including Global Health Status and functional subscales, where higher scores (range, 0 to 100) indicate better HRQoL. Time to definitive deterioration (TTD) based on a 10% decrease from baseline for GHS and for the physical, emotional, and social function subscales was determined using the Kaplan-Meier method. Treatment arms were compared using a 2-sided log-rank test stratified by prior use of lapatinib.

Results: Overall, there was no significant difference in median TDD of HRQoL between treatment arms. The median TTD in global health status score was 8.3 months for EVE (95% confidence interval [CI], 6.9-11.5) vs 7.3 months for PBO (95% CI, 5.6-10.4; P = .8386). The median TTD in the physical, emotional, and social function subscale scores showed no significant difference between arms. For example, median TTD in the physical function subscale score was 12.0 months (95% CI, 8.3-14.1) for EVE vs 12.5 months (95% CI, 8.3-20.9) for PBO (P = .4251), and median TTD in the emotional function subscale score was 15.2 months (95% CI, 9.2-17.3) for EVE vs 12.5 months (95% CI, 9.7-16.4) for PBO (P = .8140).

Conclusions: These analyses demonstrate that, despite increased frequency of adverse events observed with the addition of EVE to the standard treatment of vinorelbine and trastuzumab, overall and functional HRQoL scores were not negatively impacted in patients with trastuzumab-resistant, HER2+, advanced breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-18.

Abstract P3-11-02: Women with pregnancy-associated early breast cancer achieve improved emotional well-being as a result of their cancer experience

Background: Pregnancy-associated early breast cancer (PAEBC) has increased in incidence as more women pursue childbearing at an older age. The objective of this study was to measure the impact of diagnosis and treatment on emotional health and evaluate the positive emotional outcomes in a group of women with PAEBC. Methods: Between 1989 and 2010, 81 patients were treated for PAEBC with 5-flurouracil, doxorubicin and cyclophosphamide (FAC) chemotherapy. Patients completed the Impact of Events Scale-Revised (IES-R), which is a questionnaire that measures subjective distress caused by traumatic events and the Post-traumatic Growth Inventory (PGI), which measures positive outcomes after a traumatic event. Results: Of the 81 women, 53% (43/81) completed the IES-R and 44% (36/81) also completed the PGI. The time since diagnosis ranged from 6 months to greater than 5 years. The median age of the participants was 33 years (range 26-43 years). Of the 43 patients who completed the IES-R, 91% (39/43) did not use avoidance as a primary coping strategy; they felt well equipped to deal with feelings about their diagnosis and treatment. Of patients who inadvertently thought about their diagnosis, 70% (30/43) noted that they avoided becoming upset by their thoughts. Less than 10% (9/43) of patients surveyed felt apathetic towards their diagnosis and subsequent treatment. In terms of positive outcomes, 94% (33/36) felt they were enabled to depend on others in times of crises and felt a greater appreciation for people and their kindness following their diagnosis of PAEBC. Eighty-six percent (31/36) had changed their priorities about what is important in life, felt more compassionate towards others, and felt a greater appreciation for the value of their own life. In addition, 86% (30/36) of patients indicated that they had discovered their inner strength and felt more inclined to change things in their life. Finally, 75% of patients surveyed felt they had developed a stronger religious faith because of their experience and had a better understanding of spiritual matters. The majority of patients reported improvement in interpersonal skills – placing more effort into their relationships and sharing a greater sense of closeness with others. Conclusions: Although women who experience PAEBC are thought to be at high risk for experiencing psychosocial distress, these findings suggest that most do not suffer negative emotional consequences; in fact, these data suggest that they often achieve improved emotional well-being as a result of their cancer experience. It is possible that these women have better emotional outcomes because they have successfully carried a pregnancy while facing a life-threatening illness. Comparisons to other premenopausal breast cancer survivors will be crucial in interpreting these findings.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-11-02.

Abstract P5-13-03: Factors associated with prophylactic mastectomy among BRCA-positive patients with no personal history of breast cancer

Background: The rate of prophylactic mastectomy (PM) has recently increased1. A deleterious mutation in the BRCA1 or BRCA 2 genes is among the major reasons why patients pursue PM 2, 3. Women with BRCA1 or BRCA2 gene mutations have up to an 87% risk to develop an invasive breast cancer (BC), and up to 45% risk for ovarian cancer (OC)2, 3. Most studies evaluating predictors of PM in BRCA mutation carriers are performed among women with breast cancer; however, accurate predictors for PM among unaffected BRCA mutation carriers are less defined. In a single institution study we aimed to evaluate predictors of PM among BRCA carriers with no personal history of breast cancer.

Method: One hundred seventy seven women with no personal history of BC, who tested positive for a BRCA1 or BRCA 2 germline mutation, were included in the study. Patients’ characteristics were obtained from a prospectively maintained research database under an IRB approved protocol at UT MD Anderson Cancer Center. Univariate analyses using chi-square and logistic regression analysis were used to determine predictive factors associated with PM. The patient characteristics examined included age, martial and educational status, bilateral salphingo-oophorectomy (BSO), family history of 1st and 2nd degree relatives with breast (BC) and ovarian cancer (OC), race, and BRCA genetic test result.

Results: Out of the 177 BRCA1 and BRCA 2 positive patients, 51 (29%) elected for PM. The average age for the cohort was 44 years (range 23-91). The majority were Caucasian (81%), and married (72%) with a college degree (64%). One hundred sixty-four (92%) patients had 1st and 2nd degree relatives with BC, 93 (53%) had 1st and 2nd degree relatives with OC, and 85 (48%) had undergone BSO. A logistic regression model was run to identify factors associated with undergoing PM, including family history of OC, family history of BC, BSO and age. Patients with a family history of OC were 2.5 times more likely than those without to have had a PM (p = 0.0125), and patients who had a BSO were 0.137 times less likely to have had a PM (p &lt;.0001). Only 12 patients did not have a family history of BC and none of those patients had a PM, so an Odds Ratio could not be calculated. However, it was determined through the Fisher's exact test that patients with a family history of BC were more likely to undergo a PM (p = 0.0198).

Conclusion: The rate of PM in our cohort was slightly lower than expected. Factors associated with PM included a family history of BC and OC. Interestingly, having had a BSO was associated with lower likelihood of undergoing PM (menopausal status will be further evaluated); possibly due to the knowledge that BSO reduces breast cancer risk.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-13-03.

Abstract OT2-6-14: Phase 2, single arm study of a steroid-based mouthwash to prevent stomatitis in women with hormone receptor–positive advanced breast cancer treated with everolimus plus exemestane

BACKGROUND: Stomatitis, the inflammation of mucous membranes lining the mouth and throat, is a frequent adverse event that is associated with the oral mTOR inhibitor everolimus and can significantly impact treatment adherence. Specific strategies to prevent and/or lessen the severity of everolimus-associated stomatitis are not well documented. Steroid mouthwashes and steroid gels or pastes used to treat recurrent aphthous stomatitis may be effective for stomatitis associated with everolimus. This phase 2, single-arm study will evaluate a steroid-based therapeutic intervention to prevent stomatitis (Grade ≥2) in breast cancer patients taking everolimus + exemestane.

METHODS: Eligible participants will be patients with HR-positive, HER2-negative advanced breast cancer with no evidence of oral stomatitis or other oral pathology who have been prescribed everolimus + exemestane but have not yet started treatment. A baseline oral assessment will be conducted, and patients will be provided instructions on how to self-monitor for stomatitis, along with instructions to contact the study site at the first sign of oral pain or changes to the oral mucosa. All patients will be instructed to perform routine good oral care. Eligible patients will receive a steroid-based mouthwash (alcohol-free 0.5mg/5ml dexamethasone solution) prophylactically. Patients will be instructed to perform the mouthwash regimen four times per day and swish the mouthwash in mouth for a minimum of 120 seconds before spitting it out. Patients will be instructed to abstain from eating or drinking for at least an hour after taking the mouthwash. Mouthwash regimen will begin on the first day of everolimus after administration of the dose and patients will continue the regimen for the first 4 months of everolimus therapy.

Primary endpoint is the incidence of stomatitis (Grade ≥2) at 2 months defined as meeting at least one of the following criteria: ≤50 on Normalcy of Diet Scale to assess oral intake and a rating of 7 on two consecutive days or a rating of 8, 9 or 10 on any one day using Visual Analog Scale to assess oral pain. Evidence of stomatitis must be confirmed by investigator on physical exam and/or phone call assessment. Secondary endpoints include average number of times per day the mouthwash regimen was performed and time to resolution of stomatitis (Grade ≥2) that occurs during the trial. Assuming a 13% absolute reduction in the rate of grade ≥ stomatitis from the historical control rate of 33% and one sided Type 1 error = 0.05 and power = 80%,73 evaluable patients will be needed. To account for 25% of the total patient population being non-evaluable, 97 patients will be enrolled for this study.

Supported by funding from Novartis Pharmaceuticals Corporation.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT2-6-14.

Prognostic value of the trichorhinophalangeal syndrome-1 (TRPS-1), a GATA family transcription factor, in early-stage breast cancer

BACKGROUND

TRPS-1 is a new GATA transcription factor that is differentially expressed in breast cancer (BC) where it been found recently to regulate epithelial-to-mesenchymal transition (EMT).

PATIENTS AND METHODS

We carried out a quantitative immunohistochemistry (qIHC) analysis of TRPS-1 expression in 341 primary-stage I-III BC samples in relation to patient clinical characteristics as well as its prognostic value, especially in an estrogen receptor-positive (ER+) subgroup.

RESULTS

Higher TRPS-1 expression was significantly associated with a number of clinical and pathological characteristics as well as with improved overall survival (OS) and disease-free survival (DFS). Among stage I/II ER+ BC patients who received endocrine therapy alone, those with high TRPS-1 expression had significantly longer OS and DFS. There was also a strong association between TRPS-1 levels and the EMT marker E-cadherin in the ER+ invasive ductal carcinoma cases. Analysis of gene expression data on a panel of BC lines found that TRPS-1 expression was low or absent in BC lines having enriched mesenchymal features.

CONCLUSIONS

Our data indicated that TRPS-1 is an independent prognostic marker in early-stage BC and a new EMT marker that can distinguish patients with ER+ BC who will respond longer to adjuvant endocrine therapy.

Pathologic complete response to neoadjuvant chemotherapy with trastuzumab predicts for improved survival in women with HER2-overexpressing breast cancer

BACKGROUND

We sought to determine the prognostic value of pathologic response to neoadjuvant chemotherapy with concurrent trastuzumab.

PATIENTS AND METHODS

Two hundred and twenty-nine women with HER2/neu (HER2)-overexpressing breast cancer were treated with neoadjuvant chemotherapy plus trastuzumab between 2001 and 2008. Patients were grouped based on pathologic complete response (pCR, n = 114) or less than pCR (<pCR, n = 115); as well as by pathologic stage. Locoregional recurrence-free (LRFS), distant metastasis-free (DMFS), recurrence-free (RFS), and overall survival (OS) rates were compared.

RESULTS

The median follow-up was 63 (range 53-77) months. There was no difference in clinical stage between patients with pCR or <pCR. Compared with patients achieving <pCR, those with the pCR had higher 5-year rates of LRFS (100% versus 95%, P = 0.011), DMFS (96% versus 80%, P < 0.001), RFS (96% versus 79%, P < 0.001), and OS (95% versus 84%, P = 0.006). Improvements in RFS and OS were seen with decreasing post-treatment stage. Failure to achieve a pCR was the strongest independent predictor of recurrence (hazard ratio [HR] = 4.09, 95% confidence interval [CI]: 1.67-10.04, P = 0.002) and death (HR = 4.15, 95% CI: 1.39-12.38, P = 0.011).

CONCLUSIONS

pCR and lower pathologic stage after neoadjuvant chemotherapy with trastuzumab are the strongest predictors of recurrence and survival and are surrogates of the long-term outcome in patients with HER2-overexpressing disease.

P2-13-05: Breast Cancer, BRCA Mutations and Attitudes Regarding Pregnancy and Preimplantation Genetic Diagnosis

Background: Breast cancer is associated with treatment-related infertility and has been demonstrated to be a major concern for premenopausal survivors. Detection of a BRCA deleterious mutation may also affect attitudes regarding future childbearing. Preimplantation genetic diagnosis (PGD) allows women to use in vitro fertilization (IVF) to implant only those embryos without a BRCA mutation. The ability to test the fetus for BRCA mutations is also available through amniocentesis and chorionic villus sampling (CVS). The objective of this study was to evaluate attitudes about childbearing and fertility in women being evaluated for a BRCA mutation. Methods: Women with childbearing potential who were referred to the Clinical Cancer Genetics Clinic to be evaluated for a BRCA mutation were invited to participate in this survey. The questionnaire was administered prior to genetic counseling. A follow-up was administered after the BRCA results were disclosed. The survey queried participants regarding their attitudes on fertility, pregnancy as it may relate to cancer and the potential of a BRCA mutation. Other questions detailed attitudes regarding IVF, PGD, and CVS in these instances. Descriptive statistics were used. Results: One hundred and twenty-eight women completed pre-questionnaires and to date 76 have completed post results disclosure questionnaires. The mean age was 33 (range 21–44) with 69.5% with a diagnosis of breast cancer, 39.8% received chemotherapy and 60.9% already had at least 1 biological child. A future child was desired by 45.3% although 53.1% worried that their children would have an increased risk of cancer. Regarding PGD, although only 30.9% (38/123) said that they would use PGD, 80.2% felt that the testing should be available to families with inherited cancers. Regarding fetal testing via amniocentesis or CVS, 29.7% would have the fetus tested and 7% would consider termination if a genetic mutation was identified. Additionally, 69.5% felt it was important to receive fertility counseling and treatment at the same place where they receive their cancer care. To date 8 women have been diagnosed with a BRCA1 mutation and 4 with a BRCA2 mutation. When asked similar questions after their genetic results were disclosed, 2 women who had previously stated they would not use PGD changed their mind. Conclusions: Future pregnancies are important to many breast cancer survivors. BRCA mutation carriers have the option to have children without passing on their genetic risk for cancer. Although few would use these interventions, a large majority felt it was important to have information about these choices and to have options for fertility preservation options addressed at the center where cancer care is delivered.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-13-05.

P2-13-04: Testing Women with Invasive Lobular Breast Cancer for BRCA Mutations

Background: Infiltrating lobular carcinoma (ILC) is the second most common type of invasive breast cancer behind infiltrating ductal carcinoma (IDC). ILC makes up approximately eight percent of all invasive lesions. In addition, the mixed ductal and lobular carcinoma histology makes up approximately seven percent of all invasive diagnoses.

There are several biologic differences that are demonstrated by ILC compared to other common pathologies. They are more frequently bilateral and multicentric. They tend to be seen in women slightly older than the average age of diagnosis and are usually ER positive. It is also known that individuals with a genetic predisposition have an increased risk to develop breast cancers. Women with a mutation in their CDH1 gene have up to a 39% chance to develop ILC. The majority of hereditary breast cancer is caused by germ line mutations in the BRCA1 and BRCA2 genes. Women with a mutation in their BRCA1 or BRCA2 gene have up to an 87% risk to develop an invasive breast cancer, however, the presence of ILC in this population has not been well defined. Therefore, the aim of this study is to evaluate the rate of germline BRCA mutations in a cohort of patients both with pure ILC, as well as mixed ILC/IDC.

Methods: A retrospective chart review revealed one hundred and sixty nine women with ILC and mixed ILC/IDC who underwent genetic testing for mutations in the BRCA1 and BRCA2 genes through the Clinical Cancer Genetics Program at M. D. Anderson Cancer Center. Women are referred for genetic testing using referral guidelines based on the NCCN guidelines, this usually involves a personal history of early onset breast cancer and/or a family history of breast and/or ovarian cancer.

Results: Out of the 169 patients, 19 (11.24%) were found to have a germline mutation in their BRCA1 or BRCA2 gene. A significant majority (73.7%) of these patients were BRCA2 positive. Five women tested for a variant of uncertain significance. The average age of diagnosis for the cohort was 55.6 years (range 30–87); while the average age of diagnosis for a positive patient was 49.4 years (range 30–72). Of the 62 women with pure ILC, 5 (8.06%) were positive for a BRCA gene mutation. Historically, out of all the patients with breast cancer referred and tested through the Clinical Cancer Genetics Program, approximately 15% test positive, and research shows that in the general population, 7–10% of breast cancer patients will test positive.

Conclusions: while the positivity rates between the cohorts are not statistically significant, we have shown that patients with a BRCA mutation can develop ILC in addition to the more commonly seen IDC. We suggest that patients continue to be referred for genetic counseling according to the NCCN guidelines, regardless of the pathology of their tumor.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-13-04.

P4-10-06: Evaluation of BRCAPro Risk Assessment Model in Patients with Ductal Carcinoma In Situ

Background: The BRCAPRo model is used to predict a patient's likelihood to possess a BRCA1 or BRCA2 gene mutation based upon personal and family history. Ductal carcinoma in situ (DCIS) is considered a non-invasive condition which can progress to an invasive breast cancer if left untreated. Currently, DCIS is not specifically accounted for in the BRCAPro model, thereby causing DCIS to be weighted in the same manner as an invasive breast cancer diagnosis. Historically, a diagnosis of DCIS has been entered as having developed into an invasive breast cancer ten years later. However, there are no standard guidelines of how DCIS should be entered. We sought to determine if there were any differences in how DCIS was treated in the BRCAPro model to predict the more effective method in calculating the BRCAPro. Methods: Women with pure DCIS, who were referred for genetic counseling and underwent genetic testing, were included in the study. The likelihood of carrying a BRCA mutation was calculated using the BRCAPRO model (Version 5.1). Patient characteristics which were entered into the BRCAPro model include: tumor markers (estrogen receptor-ER and progesterone receptor-PR), history of oophorectomy prior to diagnosis, family history of 1st and 2nd degree relatives with breast and ovarian cancer, race and Ashkenazi Jewish ancestry. Each patient's BRCAPro risk estimate was calculated and compared by entering DCIS at the presenting age of diagnosis and by adding 10 years to the age of diagnosis. Descriptive statistics and a student's t-test were used to compare BRCAPro estimates between the two groups. Results: Ninety-five patients with pure DCIS underwent genetic counseling and testing. The average age of DCIS diagnosis was 45 years (range 26–65). Of the 95 DCIS patients included in the study 21% (n=20) tested positive for a BRCA gene mutation (8 BRCA1 and 12 BRCA2), 77% (n=74) test negative and 0.01% (n=1) had a variant of uncertain significance. Overall, DCIS patients who tested positive for a BRCA mutation had a higher BRCAPro (40%) than patients who tested negative (12%) when presenting age of diagnosis was assessed. When 10 years was added, the BRCAPro estimate was still higher amongst BRCA positive patients (28%) than BRCA negative patients (8%). The mean BRCAPro probability when DCIS was entered at presenting age of diagnosis was 18% (0.1−95.4) versus 12% (0.1−89.9) when calculated 10 years later. Conclusion: In our cohort there was no significant difference in BRCAPro probability whether DCIS was entered at the presenting age of diagnosis or 10 years later (p=0.1). However, future studies are needed to determine the most effective method to incorporate DCIS into the BRCAPro model in order to determine those individuals who may or may not be at increase risk to possess a BRCA gene mutation.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-10-06.

Communication of BRCA1 and BRCA2 genetic test results to health care providers following genetic testing at a tertiary care center

Individuals at high risk for hereditary cancers often receive genetic counseling and testing at tertiary care centers; however, they may receive care for long-term management of their cancer risk in community settings. Communication of genetic test results to health care providers outside of tertiary care settings can facilitate the long-term management of high risk individuals. This study assessed women's communication of BRCA1/BRCA2 genetic test results to health care providers outside of tertiary care settings (termed "outside" health care providers, or OHCPs) and women's perceptions regarding communication of results. Women (n = 312) who underwent BRCA1/BRCA2 genetic counseling and testing completed a questionnaire assessing whether or not they shared test results with OHCPs and perceptions regarding the communication of test results to OHCPs. Most (72%) shared genetic test results with OHCPs. Women with no personal history of cancer were more likely to have shared results compared to women with a personal history of cancer. Mutation status did not significantly predict sharing of genetic information. Most reported positive perceptions regarding the disclosure of genetic test results to OHCPs. The majority did not report any concerns about potential insurance discrimination (88%) and indicated that OHCPs were able to appropriately address their questions (81%). Although most women shared their genetic test results with OHCPs, those with a personal history of cancer may need further encouragement to share this information. Tertiary care centers should facilitate outreach and education with OHCPs in order to assure appropriate long-term cancer risk management for high risk populations.

Abstract P6-10-04: Outcome of Triple Negative Breast Cancer in Patients with or without Deleterious BRCA Mutations

Background: Triple-negative breast cancer (TNBC) affects 10-17% of all breast cancers and is associated with a poor prognosis. The biology of TNBC is poorly understood; however, it has been shown that up to 60% of BRCA1 mutation carriers develop TNBC. The aim of this study was to determine if there were differences in the progression-free survival (PFS) and overall survival (OS) rates of BRCA mutation-associated TNBC and Non-BRCA mutation-associated TNBC.

Methods: Patients with TNBC who were referred between 1997 and 2010 for genetic counseling were included in the analysis. Data was collected from a prospectively maintained IRB-approved research database. All patients with one primary breast cancer and negative expression of ER, PR, and Her2 were included in this study. A Kaplan-Meier survival analysis was performed to determine survival outcomes. Results: Out of 98 TNBC patients, 48 (48 %) were BRCA negative, and 47 (49%) were found to have a deleterious BRCA mutation (42 BRCA1 and 5 BRCA 2); 3 (3%) patients had a variant of uncertain significance in BRCA2 and were removed from study. The median age of diagnosis for BRCA positive TNBC was 42 years (range, 21-71) and for BRCA negative TNBC was 40.5 years (range, 21-64). There were no significant differences between age at diagnosis, nuclear grade, stage (I-III), or tumor histology of BRCA positive and BRCA negative TNBCs. The PFS for BRCA positive patients was 230.7 (range, 2-271) months and for BRCA negative was 203.1 (range, 2-258) months (p = 0.19). The overall survival (OS) for BRCA positive patients was 263.4 (range, 2-292) months and for BRCA negative 236.2 (2-279) months (p = 0.39). Conclusion: Outcome of triple-negative breast cancer is not different in BRCA mutation carriers versus non carriers. Further studies need to evaluate whether different therapies will change the outcome in these subgroups of TNBC.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-10-04.