Circulating tumor DNA association with residual cancer burden after neoadjuvant chemotherapy in triple-negative breast cancer in TBCRC 030

BACKGROUND

We aimed to examine circulating tumor DNA (ctDNA) and its association with residual cancer burden (RCB) using an ultrasensitive assay in patients with triple-negative breast cancer (TNBC) receiving neoadjuvant chemotherapy.

PATIENTS AND METHODS

We identified responders (RCB 0/1) and matched non-responders (RCB 2/3) from the phase II TBCRC 030 prospective study of neoadjuvant paclitaxel versus cisplatin in TNBC. We collected plasma samples at baseline, 3 weeks and 12 weeks (end of therapy). We created personalized ctDNA assays utilizing MAESTRO mutation enrichment sequencing. We explored associations between ctDNA and RCB status and disease recurrence.

RESULTS

Of 139 patients, 68 had complete samples and no additional neoadjuvant chemotherapy. Twenty-two were responders and 19 of those had sufficient tissue for whole-genome sequencing. We identified an additional 19 non-responders for a matched case-control analysis of 38 patients using a MAESTRO ctDNA assay tracking 319-1000 variants (median 1000 variants) to 114 plasma samples from 3 timepoints. Overall, ctDNA positivity was 100% at baseline, 79% at week 3 and 55% at week 12. Median tumor fraction (TFx) was 3.7 × 10-4 (range 7.9 × 10-7-4.9 × 10-1). TFx decreased 285-fold from baseline to week 3 in responders and 24-fold in non-responders. Week 12 ctDNA clearance correlated with RCB: clearance was observed in 10 of 11 patients with RCB 0, 3 of 8 with RCB 1, 4 of 15 with RCB 2 and 0 of 4 with RCB 3. Among six patients with known recurrence, five had persistent ctDNA at week 12.

CONCLUSIONS

Neoadjuvant chemotherapy for TNBC reduced ctDNA TFx by 285-fold in responders and 24-fold in non-responders. In 58% (22/38) of patients, ctDNA TFx dropped below the detection level of a commercially available test, emphasizing the need for sensitive tests. Additional studies will determine whether ctDNA-guided approaches can improve outcomes.

TBCRC 030: a phase II study of preoperative cisplatin versus paclitaxel in triple-negative breast cancer: evaluating the homologous recombination deficiency (HRD) biomarker

BACKGROUND

Cisplatin and paclitaxel are active in triple-negative breast cancer (TNBC). Despite different mechanisms of action, effective predictive biomarkers to preferentially inform drug selection have not been identified. The homologous recombination deficiency (HRD) assay (Myriad Genetics, Inc.) detects impaired double-strand DNA break repair and may identify patients with BRCA1/2-proficient tumors that are sensitive to DNA-targeting therapy. The primary objective of TBCRC 030 was to detect an association of HRD with pathologic response [residual cancer burden (RCB)-0/1] to single-agent cisplatin or paclitaxel.

PATIENTS AND METHODS

This prospective phase II study enrolled patients with germline BRCA1/2 wild-type/unknown stage I-III TNBC in a 12-week randomized study of preoperative cisplatin or paclitaxel. The HRD assay was carried out on baseline tissue; positive HRD was defined as a score ≥33. Crossover to an alternative chemotherapy was offered if there was inadequate response.

RESULTS

One hundred and thirty-nine patients were evaluable for response, including 88 (63.3%) who had surgery at 12 weeks and 51 (36.7%) who crossed over to an alternative provider-selected preoperative chemotherapy regimen due to inadequate clinical response. HRD results were available for 104 tumors (74.8%) and 74 (71.1%) were HRD positive. The RCB-0/1 rate was 26.4% with cisplatin and 22.3% with paclitaxel. No significant association was observed between HRD score and RCB response to either cisplatin [odds ratio (OR) for RCB-0/1 if HRD positive 2.22 (95% CI: 0.39-23.68)] or paclitaxel [OR for RCB-0/1 if HRD positive 0.90 (95% CI: 0.19-4.95)]. There was no evidence of an interaction between HRD and pathologic response to chemotherapy.

CONCLUSIONS

In this prospective preoperative trial in TNBC, HRD was not predictive of pathologic response. Tumors were similarly responsive to preoperative paclitaxel or cisplatin chemotherapy.

Abstract OT3-04-02: The DORA trial: A non-comparator randomised phase II multi-center maintenance study of olaparib alone or olaparib in combination with durvalumab in platinum treated advanced triple negative breast cancer (TNBC)

Background: Recent data from the OlympiaD study revealed an improvement in response rate and progression-free survival (PFS) with the PARP inhibitor (PARPi) olaparib vs. standard of care chemotherapy in patients with metastatic breast cancer who harbor germline BRCA (gBRCA) mutations. Maintenance PARPi has improved median PFS in relapsed ovarian cancer regardless of gBRCA mutation status or HRD status. The similarities between the molecular aberration profiles of high-grade serous ovarian cancer and TNBC invites exploration of maintenance PARPi in mTNBC. Furthermore, because durable responses have been reported in subsets of patients with metastatic TNBC (mTNBC) with checkpoint blockade and because high mutational load is associated with both gBRCA and TNBC, these patients may be particularly susceptible to immunotherapy with PARPi. Thus, we hypothesize that olaparib either alone or in combination with the PD-L1 inhibitor durvalumab will be active in TNBC subjects who have responded to platinum-based chemotherapy.

Trial design: DORA is a non-comparator randomized, international, multicenter phase II study designed to explore the efficacy of olaparib with or without durvalumab as maintenance therapy in platinum-treated mTNBC. Subjects will be enrolled following four cycles of treatment with a platinum-based (cisplatin or carboplatin) chemotherapy as single agent or combination therapy. Subjects deriving clinical benefit (CR / PR / SD) with platinum-based therapy as determined by the treating physician will be eligible and randomized in a 1:1 ratio. Patients in arm 1 will receive olaparib orally 300mg BID continuously and in arm 2 will receive olaparib orally 300mg BID continuously in combination with durvalumab 1500mg IV every 4 wks. Tumor responses will be assessed every 8 wks.

Eligibility criteria: Subjects with mTNBC who are receiving platinum-based chemotherapy and who have had no more than 2 lines of chemotherapy in the metastatic or advanced setting, with one of those being a platinum, will be included in this trial. Eligible patients must have been assessed by their treating physicians to have derived clinical benefit with platinum based therapy. Archival tissue or fresh biopsy samples are mandated for biomarker analyses.

Aims:The primary endpoint is PFS; the key secondary endpoint is overall survival.

Statistical methods: The sample size is calculated based upon data derived from contemporary trials of chemotherapy in mTNBC. In both arms of the study, it is proposed to test a null hypothesis of a median PFS of 2 months against an alternative hypothesis of a median PFS of 4 months; there is no intention to make a formal statistical comparison between the two treatment arms. To test this hypothesis, assuming an exponential PFS distribution, use of an exponential MLE test, a two-sided significance level of 5% and a power of 90%, 25 subjects are required per arm.

Target accrual: To allow for a drop-out rate of approximately 20%, the sample size per arm will be inflated to 30 subjects. We plan to enroll approximately 60 subjects with mTNBC from 6 centers.

ClinicalTrials.gov Identifier: NCT03167619

Citation Format: Dent R, Tan T, Kim S-B, Traina T, McArthur H, Im Y-H, Creel T, Blackwell K. The DORA trial: A non-comparator randomised phase II multi-center maintenance study of olaparib alone or olaparib in combination with durvalumab in platinum treated advanced triple negative breast cancer (TNBC) [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 OT3-04-02.

Abstract P4-21-34: Phase II study of gemcitabine, trastuzumab, and pertuzumab for HER2-Positive metastatic breast cancer after prior pertuzumab-based therapy

Background: The combination of taxanes with trastuzumab (H) and pertuzumab (P) for first line treatment of HER2-positive metastatic breast cancer (MBC) is associated with improved progression-free survival (PFS) and overall survival (OS). Treatment per physician's choice with anti-HER2 therapy after second line therapy is associated with a median PFS of 3 months. While continued use of H in therapeutic combinations after progression on H-based therapy is common, the efficacy of continuing HP-based treatment after progression on P-based therapy is unknown.

Methods: This is a single arm phase II trial of gemcitabine (G) with HP. Eligible patients had HER2-positive (IHC 3+ or FISH ≥ 2.0) MBC with prior HP-based treatment and ≤ 3 prior chemotherapies. Patients received G (1200 mg/m2) on days 1 and 8 of a q 3 week (w) cycle, and H (8 mg/kg load → 6 mg/kg) and P (840 mg load → 420 mg) q3w. The primary endpoint is PFS at 3 months. Secondary endpoints include OS, safety and tolerability. An exploratory endpoint is to compare PFS by RECIST criteria versus 18-F FDG-PET response criteria. Using a Simon optimal 2-stage design, 21 patients were enrolled in stage 1. The successful 3-month PFS rate for stage 1 was set at 57% to allow accrual to stage 2 for a total of 45 patients. The study therapy will be considered successful if at least 27/45 (60%) patients are progression free at 3 months.

Results: As of June 9, 2016, 28 patients are enrolled; 21 are evaluable at 3 months and 7 have not had 3-month evaluation. At 3 months, 16/21 (76%) are progression free; 5 patients have progressed. The 3 month-PFS results for evaluable patients will be updated. There are no cardiac or febrile neutropenic events to date. Initially, 5 of 22 (23%) patients required G dose reduction (4 due to grade 3 neutropenia and 1 due to grade 3 vomiting) and the study was amended to lower initial G dose to 1000 mg/m2.

Conclusions: The preliminary 3 month-PFS is 76% (95% CI 55% to 89%) in evaluable patients, and updated data will be presented. These findings suggest clinical benefit when P is continued beyond progression.

Citation Format: Iyengar NM, Smyth L, Lake D, Gucalp A, Singh JC, Traina TA, DeFusco P, Dickler MN, Fornier MN, Goldfarb S, Jhaveri K, Modi S, Troso-Sandoval T, Argolo D, Jack K, Ulaner G, Jochelson M, Baselga J, Norton L, Hudis CA, Dang CT. Phase II study of gemcitabine, trastuzumab, and pertuzumab for HER2-Positive metastatic breast cancer after prior pertuzumab-based therapy [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 P4-21-34.

Abstract P2-08-05: Phase I/II trial of palbociclib in combination with bicalutamide for the treatment of androgen receptor (AR)+ metastatic breast cancer (MBC)

This abstract was withdrawn by the authors.

Weekly paclitaxel with trastuzumab and pertuzumab in patients with HER2-overexpressing metastatic breast cancer: overall survival and updated progression-free survival results from a phase II study

We previously reported progression-free survival (PFS) results on a phase II trial of weekly paclitaxel, trastuzumab, and pertuzumab in patients with human epidermal growth factor receptor 2(HER2)-positive metastatic breast cancer (MBC) treated in the first- and second-line setting. Here, we report results for overall survival (OS) and updated PFS after an additional year of follow-up. Patients with HER2-positive MBC with 0-1 prior treatment were eligible. Treatment consisted of paclitaxel (80 mg/m(2)) weekly, and trastuzumab (loading dose 8 mg/kg → 6 mg/kg) and pertuzumab (loading dose 840 mg → 420 mg) every 3 weeks, all given intravenously. Primary endpoint was 6-month PFS. Secondary endpoints included median PFS, 6-month and median OS. Evaluable patients received at least one full dose of treatment. From January 2011 to December 2013, 69 patients were enrolled: 51 (74 %) and 18 (26 %) treated in first- and second-line metastatic settings, respectively. As of July 1, 2015, the median follow-up was 33 months (range 3-49 months; 67 patients were evaluable for efficacy). The median OS was 44 months (95 % CI 37.5-NR) overall and 44 months (95 % CI 38.3-NR) and 37.5 months (95 % CI 30.3-NR) for patients with 0 and 1 prior metastatic treatment, respectively; 6-month OS was 98 % (95 % CI 90-1). The 6-month PFS was 86 % (95 % CI 75-93) overall and 89 % (95 % CI 76-95) and 78 % (95 % CI 51-91) for patients with 0 and 1 prior therapy, respectively; and median PFS was 21.4 months (95 % CI 14.1-NR) overall and 25.7 months (95 % CI 14.1-NR) and 16.9 months (95 % CI 8.5-NR) for patients with 0-1 prior treatment, respectively. Treatment was well tolerated. Updated analysis demonstrates that weekly paclitaxel, when added to trastuzumab and pertuzumab, is associated with a favorable OS and PFS and offers an alternative to docetaxel-based therapy. http://www.ClinicalTrials.gov NCT0127604.

Abstract OT2-01-03: A phase 1/2 study of once-daily oral VT-464 in patients with advanced androgen receptor (AR) positive triple negative (TNBC) or estrogen receptor (ER) positive breast cancer (BC)

VT-464, an oral dual lyase-selective CYP17 inhibitor and AR antagonist (wild-type and mutated forms [e.g., F876L and T877A]), is in multiple Phase (Ph) 2 studies as treatment for men with castration-resistant prostate cancer (CRPC). VT-464 inhibits the growth of multiple BC cell lines in vitro including MCF7 (ER(+)/AR low), tamoxifen-resistant MCF7, and MDA-MB-453 (ER(-)/AR(+)) in a dose-dependent manner and with greater potency/efficacy than enzalutamide (submitted, Ellison et al., 2015). A subset of TNBC and most ER(+) BC express AR, making them potential targets for VT-464 since it directly inhibits both androgen/estrogen synthesis and AR transcriptional activity.

Objectives: The primary objective of Ph 1, now enrolling, is to establish the once-daily dose of VT-464 in women. Secondary objectives include safety, PK and efficacy endpoints, including determination of clinical benefit rate (CBR) which is the primary objective of Ph 2. Exploratory objectives include the determination of the extent of AR expression and signaling in breast tissue and to evaluate the relationship of expression with VT-464 effects on circulating tumor biomarkers, circulating hormones and clinical outcomes.

Study Design: This study is an open-label, single arm, Ph 1/2 study of VT-464 in women with AR(+) TNBC or ER(+)/HER2 normal unresectable locally advanced or metastatic BC. Ph 1 will follow a modified 3+3 Fibonacci design with cohort expansion to 6 patients following a single DLT in the first 28-days of treatment. Approximately 2-3 dose-levels will be explored in Ph 1. Ph 1 start dose will be the MTD for men with CRPC. AR(+) TNBC and ER(+)/HER2 BC cohorts will be expanded in Ph 2 using the MTD from Ph 1. Ph 2 will follow a Simon's two-stage design with pre-determined futility parameters. Eligible patients will have ER≥1% BC or AR≥1% (as determined by central IHC testing using the Dako antibody) TNBC. ER(+) patients must be postmenopausal and must have received at least 1 prior line of endocrine therapy. Additional eligibility criteria include: ≥ 18 years of age, ECOG PS ≤ 1, unresectable locally advanced or metastatic BC, available representative tumor specimen to enable correlative science.

Treatment Plan: Eligible patients will receive VT-464 once-nightly with dinner in a continuous dosing schedule. Adverse events and concomitant medications will be collected from the time of signing of informed consent until 30 days after end of study visit (EOS). Safety labs will be monitored monthly through EOS. Dense PK will be collected after the first dose of study drug in Ph 1 and single morning samples collected approximately every two cycles thereafter in Ph 1 and Ph 2 until EOS. Blood samples for steroids, circulating tumor DNA and circulating tumor cells will be collected through Cycle 2 and then at EOS. Tumor biopsy will be collected at baseline and at disease progression. Radiographic response will be assessed every 8 weeks and EOS.

Patient Accrual: Accrual is ongoing with 12-18 patients expected to be enrolled in Ph 1.

Citation Format: Gucalp A, Hudis C, Norton L, Patil S, Kurman MR, Eisner JR, Moore WR, Traina TA. A phase 1/2 study of once-daily oral VT-464 in patients with advanced androgen receptor (AR) positive triple negative (TNBC) or estrogen receptor (ER) positive breast cancer (BC). [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 OT2-01-03.

Abstract PD3-06: Safety and efficacy of anti-Trop-2 antibody drug conjugate, sacituzumab govitecan (IMMU-132), in heavily pretreated patients with TNBC

Background: Triple-negative breast cancer (TNBC) comprises about 15% of all breast cancer types, and has a particularly aggressive course. Following first-line therapy, the median PFS is <3 months, and OS is <10 months. Therefore, new treatment strategies are needed. Since Trop-2 is expressed in >90% of TNBC, as measured by IHC, we conducted a trial to evaluate the safety and efficacy of a humanized anti-Trop-2 monoclonal antibody conjugated to a high concentration of SN-38, a camptothecin that is a topoisomerase I inhibitor and the active metabolite of the prodrug irinotecan, with 2-3 logs higher potency than the prodrug.

Methods: After establishing the optimal repeated dose in a Phase I trial (ClinicalTrials.gov, NCT01631552) involving many different solid cancer types, an expanded Phase II was undertaken in a number of cancers, including TNBC. Patients received 8 or 10 mg/kg IMMU-132 i.v. on days 1 and 8 of 21-day repeated cycles. Assessments of safety and response by RECIST1.1 were made weekly and bimonthly, respectively. Tumor biopsies (archival, at baseline prior to treatment, and at disease progression) were obtained when safe and feasible.

Results: As of May 10, 2015, 58 patients with TNBC, with a median of 4 prior therapies (range, 1-11), were treated with IMMU-132. Grade 3-4 toxicities included neutropenia (26%), febrile neutropenia (2%), diarrhea (2%), anemia (4%), and fatigue (4%). No patient developed antibodies to SN-38 or the antibody, and no patient discontinued therapy due to toxicity. Tumor responses were defined as ORR (CR+PR) in 31% of 49 evaluated patients, including 2 with CR, and a clinical benefit ratio (CR+PR+SD>6 mo) of 49% (63% with SD>4 mo; 23 patients continuing treatment after 1st assessment). The current median progression-free survival is 7.3 months with 44% maturity in 50 patients treated at the 8 or 10 mg/kg dose level. Overall survival data are still not mature 20 months after enrollment of first patient. Clinical efficacy correlated to biomarker studies, including Trop-2 expression (target of antibody), topoisomerase-1 expression (target of SN-38), and homologous recombinant deficiency (HRD) assay (marker of DNA repair), is being studied. Immunohistochemistry results in archival specimens currently show 97% positivity of Trop-2 among 34 specimens evaluated, with 79% having high intensity (2+/3+) staining.

Conclusions: The Trop-2-targeting IMMU-132, delivering cytotoxic doses of the topoisomerase I inhibitor, SN-38, shows manageable toxicity, and encouraging anti-tumor activity in relapsed/refractory patients with TNBC. This ADC appears to have a high therapeutic index in heavily pretreated patients.

Citation Format: Bardia A, Diamond JR, Mayer IA, Starodub AN, Moroose RL, Isakoff SJ, Ocean AJ, Guarino MJ, Berlin JD, Messersmith WA, Thomas SS, O'Shaughnessy JA, Kalinsky K, Maurer M, Chang JC, Forero A, Traina T, Gucalp A, Wilhelm F, Wegener WA, Maliakal P, Sharkey RM, Goldenberg DM, Vahdat LT. Safety and efficacy of anti-Trop-2 antibody drug conjugate, sacituzumab govitecan (IMMU-132), in heavily pretreated patients with TNBC. [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 PD3-06.

Abstract P1-12-05: Phase 2 study of dose-dense doxorubicin and cyclophosphamide followed by eribulin mesylate with or without prophylactic growth factor for adjuvant treatment of early-stage breast cancer

Background: Eribulin has demonstrated antitumor activity and significantly improved overall survival (OS) in patients (pts) with heavily pretreated locally advanced/metastatic breast cancer (BC). This trial assessed the feasibility of eribulin as adjuvant therapy following dose-dense doxorubicin and cyclophosphamide (AC) for pts with human epidermal growth factor receptor 2 (HER2)-negative early-stage BC.

Methods: Pts with HER2(-), stage I–III, invasive BC were enrolled. Pts received dose-dense AC (doxorubicin 60 mg/m2 IV and cyclophosphamide 600 mg/m2 IV) on D1 of each 14-day cycle for 4 cycles with pegfilgrastim, followed by 4 cycles of eribulin (1.4 mg/m2 IV) on D1 and D8 every 21 days. Pts were divided into 2 cohorts: Cohort 1 did not receive any prophylactic growth factor (GF); Cohort 2 received a short course of prophylactic GF (filgrastim) on days 3, 4, 10, and 11 of each eribulin cycle. Primary endpoint of feasibility was determined as %pts who completed eribulin portion of the regimen without a dose delay (>2 days) or reduction due to eribulin-related adverse event (AE). Based on similar previous studies, the target for feasibility was 80%. Relative dose intensity of eribulin and toxicities were also summarized by cohort. Exploratory objectives include efficacy endpoints of 3-yr disease-free survival and OS.

Results: We report data from 81 pts (55 Cohort 1; 26 Cohort 2) enrolled in the study, of whom 88% completed study treatment. Pt characteristics include median age 49 yrs (range 26–69), ECOG status 0 (85%), BC stages 1/2/3 (21%/57%/22%). Of 90% (73/81) pts evaluable for feasibility, 27% and 40% of pts in Cohorts 1 and 2, respectively, had dose delay or reduction during eribulin treatment, indicating the primary endpoint was not met. Overall, results were similar between the 2 cohorts (Table). Median duration of treatment with eribulin was 10.14 weeks in both cohorts (vs 10 weeks planned). Most eribulin-related dose delays were due to grade 3 (n=18) or grade 4 (n=7) neutropenia. Non-fatal serious AEs were observed in 11% of pts in Cohort 1 and 15% in Cohort 2. Discontinuations due to AEs occurred in 6% of pts in Cohort 1 and 0 in Cohort 2. Neutropenia (all grades) was reported in 36% of pts in Cohort 1 and 42% in Cohort 2. Most common AEs (all grades) were fatigue (96%), nausea (75%), alopecia (73%), hot flush (63%), and constipation (57%).

 ACEribulin Cohort 1*Cohort 2*Cohort 1 (without GCSF)Cohort 2 (with GCSF)Relative dose intensity, mean99.5%99.0%92.0%90.9%Completed all planned doses98.2%96.2%87.0%84.0%Dose modification†12.7%15.4%35.2%40.0%GCSF, granulocyte-colony simulating factor. *With pegfilgrastim 6 mg given subcutaneously on D2 of each AC cyle; † including dose delays (>2 days)/reduction/interruptions, missing, and permanent discontinuation due to AE.

Conclusions: The primary study endpoint of >80% feasibility of planned dose delivery without any dose delays or reduction was not met. However, adjuvant treatment with dose-dense AC-eribulin was given safely, with two-thirds (67%) of pts achieving full dosing with no dose delay or reduction. Investigation into alternative dosing schedules or GF support is recommended.

Citation Format: Cadoo K, Kaufman PA, Hudis C, Chang C, Berrak E, Song J, Seidman AD, Traina TA. Phase 2 study of dose-dense doxorubicin and cyclophosphamide followed by eribulin mesylate with or without prophylactic growth factor for adjuvant treatment of early-stage 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 P1-12-05.

Abstract P1-04-01: Significance of circulating tumor cells in metastatic triple negative breast cancer: Results of an open label, randomized, phase II trial of nanoparticle albumin-bound paclitaxel with or without the anti-death receptor 5 tigatuzumab (TBCRC 019)

Background: Circulating Tumor cells (CTCs) are prognostic at baseline and first follow-up in patients with metastatic breast cancer (MBC). Using the most commonly used assay (CellSearch®), we have previously reported the ability to detect apoptotic vs. non-apoptotic CTCs in patients with MBC. However, there has been concern regarding the performance of the CellSearch® assay in patients with triple negative (TN) MBC. We hypothesized that CellSearch® is an effective assay in patients with TN MBC, and that CTC-apoptosis might further separate prognosis. Therefore, we studied CTCs in patients with TN MBC who participated in a prospective randomized phase II trial testing for activity of tigatuzumab (TIG) in combination with nanoparticle albumin-bound paclitaxel (nab-PAC) conducted by the Translational Breast Cancer Research Consortium (overall results reported by Forero A., et al, ASCO 2013).

Methods: Whole blood (WB) was drawn into a CellSave tube at baseline, day 15, and day 29 and CTC counts were determined using the CXC CellSearch® kit. Apoptosis was characterized by staining with a monoclonal antibody that detects a neo-epitope on fragmented cytokeratin (M-30) and independently by visual inspection (nucleic condensation and/or fragmentation, as well as granular cytokeratin). Association between levels of CTCs and CTC-apoptosis with the overall response rate (ORR) and progression free survival (PFS) at baseline, day 15, and day 29 was assessed using logistic regression, Kaplan Meier curves, and Cox proportional hazards modeling.

Results: Of the 60 patients entered into the trial, 52 were evaluable for CTCs. Of these, 19/52 (36.5%), 14/52 (26.9%), and 13/49 (26.5%) had elevated CTCs (≥5CTC/7.5 ml WB) at baseline, day 15, and day 29, respectively. Patients with elevated CTCs at each time point had worse PFS than patients with low or no CTCs. Hazard rates (HR) at baseline, day 15, and day 29 were 2.38 (95% CI: 1.27-4.45, p = 0.007), 2.87 (95% CI: 1.46-5.66, p = 0.002), and 3.40 (95% CI: 1.68-6.89, p = 0.001), respectively. The odds of overall response for those who had elevated CTCs compared to those who did not at baseline, day 15, and day 29, were 0.25 (95% CI: 0.073-0.81, p = 0.024), 0.18 (95% CI: 0.04-0.67, p = 0.014), and 0.06 (95% CI: 0.01-0.28, p = 0.001), respectively. There was no apparent prognostic effect comparing the degree of CTC-apoptosis vs. non-apoptosis.

Conclusions: Similar to observations in other intrinsic subgroups, CTCs were detected in a large fraction of TN MBC patients at baseline using CellSearch® assay, and reductions in CTC levels reflected response. In these homogenously prospectively enrolled TN MBC patients, regardless of treatment, CTCs are prognostic at baseline, day 15, and day 29. It does not appear that analysis of CTC-apoptosis is prognostic.

Supported by Susan G. Komen for the Cure, Veridex, LLC, Fashion Footwear Charitable Foundation of New York/QVC Presents Shoes on Sale™ (DFH), Associazione Sandro Pitigliani and by a studentship from FIRC (CP), Triple Negative Breast Cancer Foundation, The AVON Foundation, and The Breast Cancer Research Foundation.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-04-01.

Abstract P1-13-11: Adjuvant treatment of early-stage breast cancer with eribulin mesylate following dose-dense doxorubicin and cyclophosphamide: preliminary results from a phase 2, single-arm feasibility study

Background: Despite recent improvements in breast cancer outcomes, patients (pts) with high-risk, early-stage breast cancer continue to experience recurrences and death due to disease. Chemotherapy regimens with the ability to extend survival remain an important drug development goal. Eribulin mesylate has demonstrated antitumor activity and improved overall survival (OS) in pts with heavily pretreated, locally recurrent or metastatic breast cancer when compared to treatment of physician's choice. This study examines the feasibility of eribulin as adjuvant therapy following dose-dense (dd) doxorubicin (A) and cyclophosphamide (C) in patients with early-stage breast cancer.

Methods: Eligible pts have histologically confirmed, HER2-normal, stage I-III invasive breast cancer and adequate bone marrow, liver, and renal function. Treatment consists of dd AC (A 60mg/m2 IV; C 600mg/m2 IV) on Day 1 of each 14-day cycle x4 cycles, followed by eribulin mesylate 1.4mg/m2 IV over 2–5min on Days 1 and 8 every 21 days x4 cycles. Radiation/hormonal therapy were allowed per standard of care. The primary objective of feasibility is defined as the ability to complete 4 cycles of eribulin without a treatment-related dose delay (defined as >2 days) or reduction. Feasibility rates will be reported for pts with and without growth factor use. Secondary/exploratory endpoints include evaluation of the safety via NCI-CTCAEv4 of 4 cycles of AC followed by 4 cycles of eribulin, and 3-year disease-free survival and OS.

Results: As of 5/22/12, 46 of 80 planned pts have been treated; 38 pts have had ≥1 dose of eribulin and are evaluable for eribulin-related toxicity. Pt characteristics are as follows: median age 50 yrs (27–65 yrs); 100% female; ECOG of 0=81.6%; breast cancer stage at study entry: stg 1: 7.5%; stg 2: 72.5%, stg 3: 20%. Select treatment-related AEs are reported as total (all cycles) and eribulin-related events; many AEs overlapped during treatment (Table).

Abstract P6-05-02: Endocrine biomarkers in response to AR-inhibition with bicalutamide for the treatment of AR(+), ER/PR(−) metastatic breast cancer (MBC) (TBCRC011)

Background: Our group and others have identified a subset of ER/PR(−) breast cancers characterized by expression of the androgen receptor (AR) and androgen-dependent growth (Doane 2006). We conducted a proof-of-concept multicenter phase II study to test the efficacy of the AR-antagonist, bicalutamide for the treatment of AR(+) ER/PR(−) MBC (NCT00468715). Results of the primary endpoint, clinical benefit rate (CBR), were presented at ASCO (Gucalp 2012). Data for the impact of bicalutamide on circulating hormone levels in women are limited. Elevations in serum testosterone (T) and estradiol (E) have been observed for men treated with bicalutamide. We hypothesized comparable patterns of change in circulating endocrine markers in response to bicalutamide for women with MBC.

Methods: Patients (pts) with AR(+) (IHC ≥10%), ER/PR(−) (IHC <10%) MBC were eligible for treatment (tx) if ECOG performance status ≤2 and normal organ function regardless of menopausal status. There was no limit to prior tx except prior trastuzumab required if HER2(+). Tx consisted of bicalutamide 150mg orally daily in 28-day cycles (C). Toxicity assessed q4 weeks, response q12wks. Primary endpoint was CBR. Peripheral blood was collected for total and free T, E and sex hormone binding globulin (SHBG) at baseline, start of C2 (C2) and at end of study (EOS). Standard institutional assays were used. A Wilcoxon signed-rank test was done to compare baseline to C2 and EOS values.

Results: 26 patients with AR(+) ER/PR(−) MBC were treated on study. Evaluable number (n) of pts at baseline, C2 and EOS are 26, 26 and 19 respectively. Two pts remain on study. Menopausal status: pre=2, post=24. Baseline median total and free T and estradiol were consistent with expected norms, however a wide range was observed (Table). There were no significant differences observed for median free T, total T, E or SHBG between baseline and C2 or baseline and EOS. Changes in hormone levels could not be stratified by menopausal status or response to bicalutamide given small sample size. Given the wide range of baseline values, we examined the percent change for each endocrine biomarker from baseline to C2 and EOS. As shown in the Table, there was no difference in median percent change observed across time points for each biomarker.

Abstract P6-11-10: IBL2001: Phase I/II study of a novel dose-dense schedule of oral indibulin for the treatment of metastastic breast cancer

Background: Indibulin (ZI0-301) is a novel, oral, synthetic small molecule microtubule inhibitor which binds tubulin at a different site than taxanes and vinca alkaloids. Preclinical data demonstrate indibulin does not interact with acetylated (neuronal) tubulins and in clinical studies has not exhibited the neurotoxicity associated with other tubulin binders. Indibulin has potent antitumor activity in human cancer cell lines, including multidrug-, taxane-, and vinblastine-resistant. Norton-Simon modeling based on cell line data suggested that dose dense (dd) administration could optimize efficacy while limiting toxicity.

Methods: Eligible patients (pts) have metastatic or unresectable locally advanced breast cancer, ECOG performance status ≤ 2, adequate organ function, measurable or nonmeasurable disease and any number of prior therapies. Uncontrolled gastrointestinal malabsorption syndrome and grade 2 or higher peripheral neuropathy are the principal exclusions. Adverse events (AEs) are graded by CTCAE v. 4.0. Objective disease status is evaluated according to RECIST 1.1. The primary objective of the phase (Ph) I portion of the study is to determine the maximum tolerated dose (MTD) of indibulin when given in dd fashion 5 days treatment, 9 days rest using standard 3+3 dose escalation schema.

P4-02-04: Androgen Receptor (AR) Expression in a Cohort of Patients (pts) with Triple Negative Breast Cancer (TNBC)

Background

TNBC, defined by the absence of ER, PR, and HER2, is associated with higher risk of recurrence and BC-related mortality, earlier age at diagnosis, menarche, and 1st pregnancy, increased parity, higher BMI, and African-American/Hispanic race. TNBC is a heterogeneous group. Using gene expression analysis, our group described a subset of AR+ ER/PR- BC that exhibits androgen-dependent growth. In vitro studies confirmed the functional role of AR and showed that growth could be abrogated by antiandrogens.(Doane et al 2006) We translated this work into a phase II trial of bicalutamide in pts with AR+ ER/PR- metastatic BC (MBC). (NCT00468715) We now describe the prevalence and clinicopathological characteristics of AR+TNBC in primary disease in a single-institution retrospective cohort.

Methods: We identified 1,032 pts with resectable, TNBC (ER/PR<1%; HER2<2+/FISH<2.2) who had surgery at MSKCC from 1998–2006. Exclusion criteria: neoadjuvant chemotherapy, prior radiation, inflammatory/MBC. IRB approval was obtained. We constructed tissue microarrays (TMA) from 210 primary tumors (> 1 cm) with each tumor represented by three 0.6mm cores. AR was tested with DAKO antibody (Clone AR441; dilution 1:500). TMAs were digitized with a Mirax scanner. MetaMorph image analysis software was used to quantify the ratio of DAB staining to hematoxylin signal. A ratio >1 SD above mean was defined as AR+. AR+ cores were manually reviewed; false positives due to core artifact were excluded. To evaluate clinicopathological variables and differences in recurrence-free survival (RFS) and overall survival (OS) by AR status we used chi-square/t-tests and Kaplan-Meier methods/log-rank test, respectively.

Results: 169 pts had adequate cores for image analysis/quantification of AR. 10% of pts tested AR+ (17/169). Median (med) followup: AR+=6 years (yr), AR-=5.6yr. Demographic/clinicopathological variables: Table 1 (ages in med yr). Overall med age=54yr (29-84). Adjuvant chemotherapy received: AR+ 82%, AR- 87%, p =0.40; 77% received anthracycline/taxane-based therapy. Med time to distant metastasis (DM)=2.1yr (0.2−6.2yr). We were unable to demonstrate a difference in 5yr RFS (69% vs. 77%; p=0.37) or OS (68% vs. 84%; p=0.25) between AR+ and AR- TNBC.

P5-14-13: Favorable Prognosis in Patients with T1a,b Node-Negative Triple Negative Breast Cancers Treated with Multimodality Therapy

Purpose: To evaluate the clinical characteristics, natural history and outcomes in patients with ≤1cm, node-negative triple negative breast cancer (TNBC).

Materials and Methods: After excluding patients who received neoadjuvant therapy, 1,022 TNBC patients who received definitive breast surgery from 1999 to 2006 were identified from an institutional database. Among these, 194 patients had node-negative tumors ≤1cm and comprise the study population. Clinical data was abstracted and survival outcomes were analyzed.

Results: Median follow-up time was 71 months (range 2–143). Median age at diagnosis was 55.5 years (range 27–84). T stage was T1mic in 16 (8.2%), T1a in 49 (25.3%), T1b in 129 (66.5%). The majority of tumors were poorly differentiated (N= 142, 73%), lacked lymphovascular invasion (N= 170, 87.6%) and were screening-detected (69%, N=134). Breast-conserving surgery (BCS) was employed in 129 (66.5%) and mastectomy in 65 (33.5%) patients. 113 (58%) patients received adjuvant chemotherapy and 123 (63%) received whole breast radiation. Patients who received chemotherapy tended to have more adverse clinical and disease features (younger age,T1b, poor tumor grade; all p<0.05). For the entire group, 5 year local recurrence-free survival was 96% and distant metastasis-free survival was 95%, with no difference in distant relapse rates between T1mic/T1a vs. T1b patients (94.5% vs 95.5%, p=0.81 )or by receipt of chemotherapy (95.9% vs 94.5%, p=0.63).

Conclusion: Excellent 5-year locoregional and distant control rates were achievable in patients with TNBC tumors ≤ 1.0 cm, 58% of whom received chemotherapy. These results identify a group of TNBC patients with favorable outcomes following early detection and multimodality treatment.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-14-13.

Determinants of outcome in elderly patients with positive sentinel lymph nodes

614

Background: Older women are less likely to receive standard of care treatment for breast cancer. This undertreatment may be linked to the perception that elderly patients (pts) may not tolerate or derive benefit from treatment that is often viewed as “too toxic.” Methods: From July 1997 to July 2003, 1,470 pts with invasive cancer with positive sentinel lymph nodes (PSLN) by intraoperative frozen section or final pathologic exam by hematoxylin-eosin and/or immunohistochemistry (IHC). We examined sociodemographic, pathologic, and therapeutic variables that affected the outcome of elderly pts ≥70 years old. A comorbidity score was assigned using Adult Comorbidity Evaluation-27 system. Chi-square, Fisher's exact Wilcoxon tests, and multivariate logistic regression analysis were used. Results: The median age was 53 years (range 21–89) and median tumor size 1.6 cm (range 0.1–11). 1,265 (86.1%) pts were <70 years old and 205 (13.9%) pts were ≥70 years old. 183 (12.5%) pts had IHC only PSLN, 1,021 (69.5%) had 1–3 PSLN, and 266 (18%) ≥4 PSLN. Breast conservation therapy (BCT) was performed in 59.7% of pts. Elderly pts were more likely to have moderate to severe comorbidities (46% vs. 11%, p < 0.0001) and BCT (67% vs. 59%, p = 0.026), compared to pts <70 years old. Elderly pts were less likely to undergo completion ALND (73% vs. 89%, p < 0.0001), adjuvant chemotherapy (43% vs. 90%, p < 0.0001) and radiotherapy following BCT (82% vs. 90%) compared to pts <70 years old. The 5-year disease-free survival (DFS) was not significantly different for elderly pts compared to non-elderly pts (87.7% vs. 91.9%, p = 0.21), on the other hand the 5-year overall survival was significantly worse for elderly pts (80.4% vs. 93.2%, p < 0.0001), a difference that was mainly due to a significantly higher 5-year cumulative incidence of death due to other causes (13.2% vs. 1.9%, p < 0.0001). On multivariate analysis, ER or PR positive status, IHC only PSLN and T1 tumors were the only factors independently associated with improved odds of 5-year DFS. Conclusions: Tumor rather than patient factors were the primary determinants of breast cancer outcomes in our cohort of node positive breast cancer pts. Elderly breast cancer pts with an estimated life expectancy beyond 5 years should receive the same standard of care therapy as their younger counterparts.

No significant financial relationships to disclose.

PIK3CA and AKT1 mutations are independent in invasive breast cancer

Abstract #1046

Background: The PI3K-AKT pathway is the most commonly altered pathway in invasive breast cancer. Somatic mutation in PIK3CA occurs in 26-30%, while AKT1 mutation was recently noted in 4-8%, other mutations occur rarely in PIK3R1 and PTEN. The prognostic implication of PIK3CA somatic mutation is inconclusive in that moderately sized retrospective studies report differing conclusions. To explain these disparate results our hypothesis is that different PIK3CA mutations impart differences in tumor biology. In an attempt to definitively identify the prognostic importance and functional attributes that specific mutations impart to breast tumor biology we are performing a broad mutation analysis on 600 archival invasive breast tumors with greater than 10 years of follow-up.&#x2028; Methods: Archival formalin-fixed paraffin embedded (FFPE) invasive breast tumors were identified from an institutional database from 1992-1996 that had known vital status and primary breast tumor size greater than 1 cm. From the confirmed invasive tumor blocks, two 10µm sections are cut for DNA extraction, punch blocks are obtained for tissue microarray (TMA) construction for immunohistochemistry and clinical demographics are collected. DNA is extracted and quantitated. PIK3CA hotspot mutations and rare PIK3CA mutations less commonly observed but thought to impart an oncogenic phenotype along with the recently identified AKT1 (E17K) mutation are assessed using the Sequenom genome multiplex array. PIK3CA hotspot mutations and AKT1(E17K) are confirmed by additional analysis on an alternate multiplex array. The first 190 cases were also assessed by Sanger sequencing for all PIK3CA coding exons.&#x2028; Results: The multiplex arrays used for the Sequenom mutation analyses had been previously validated. Thus far 400 samples have been procured and 190 cases have undergone mutation analysis. Both native DNA and DNA that had undergone whole genome amplification (WGA) were assessed to identify the most informative method for FFPE specimens. Notably, PIK3CA amplification and Sanger sequencing or WGA and mutation analysis by Sequenom multiplex array was less sensitive for identifying mutations than using unamplified native DNA with Sequenom analysis. Native DNA was informative in greater than 98% samples (3/190 uninformative) for the majority of PIK3CA mutations. All samples were informative for the most common hotspot mutation at PIK3CA (H1047R). At this report, the incidence of PIK3CA hotspot mutations (E542K, E545K, H1047R, H1047L) is 26.3% (50/190 cases), with rare PIK3CA mutations (C420R, N345K) occurring in 2.6% of cases. The more recently identified AKT1 (E17K) mutation is identified in 4.2% of cases and occurs independently of those tumors which harbor a PIK3CA mutation.&#x2028; Discussion: Mutation analysis, demographic collection and statistical analysis will be completed and updated at the meeting. The work thus far demonstrates that assessment of small amounts of archival tissue can be easily procured and undergo mutation assessment for key mutations that may be targeted therapeutically.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1046.

Dose-dense (DD) doxorubicin and cyclophosphamide (AC) followed by weekly paclitaxel (P) with trastuzumab (T) and lapatinib (L) in HER2/neu-positive breast cancer is not feasible due to excessive diarrhea: updated results

Abstract #2108

Background: DD q 2 weekly (w) AC → P + T x 1 year (y) has an acceptable safely profile w/ congestive heart failure (CHF) rate of 1/70 pts (Dang, JCO 2008). Lapatinib (L) is effective in HER2 (+) BC. We conducted a pilot study of dd AC → w P + T + L to determine its feasibility and cardiac safety.&#x2028; Methods: Enrolled pts had HER2 (+) BC; LVEF &gt; 50%. Rx consisted of AC at 60/600 mg/m2 x 4 q 2 w (w/ pegfilgrastim 6 mg day 2) → P at 80 mg/m2 x 12 q w + T x 1 y; L (1000 mg daily beginning w/ P + T and continued x 1 y). MUGA is obtained at baseline and at months (mo) 2, 6, 9, and 18. Rx is considered feasible if 1) &gt; 80% pts can complete the PTL phase without a dose delay or reduction and 2) the cardiac event rate (CHF or cardiac death) is &lt; 4%. Pts can remain on-Rx w/ one dose reduction of L (1000 mg → 750 mg) for a G 3 event or &lt; G 3 toxicity (unacceptable).&#x2028; Results: From March 2007 to April 2008, we enrolled 95 pts. Median (med) age was 45 years (range, 28-73). At a med follow-up of 7 months, 90 are evaluable. Of the 90 pts, 34 (37%) withdrew from study during the PTL phase; 29 for a 2nd event of G 3 or unacceptable &lt; G 3 toxicities (15 G 3 diarrhea, 4 G 1/2 diarrhea, 1 G 3 rash, 2 G 2 rash, 1 G 3 dyspnea and also had G 3 diarrhea, 1 G 3 ↑QTc also had G 3 diarrhea, 1 G 3 ↑ALT also had G 3 diarrhea, 1 G 3 paronychia, 1 G 3 pneumonitis, 1 asymptomatic LVEF ↓, 1 myocarditis) and 5 for other reasons (2 personal reason, 1 PCP pneumonia, 1 progression, 1 P hypersensitivity). Overall, 25/90 (27%) pts had G 3 diarrhea and 31/90 (34%) pts required a dose reduction of lapatinib. Med LVEF at baseline is 67% (N=95), at mo 2 is 68% (N=90), at mo 6 is 65% (N=53), and mo 9 is 65% (N=28). To date there are no patient drop-outs due to significant LVEF declines after dd AC; one patient dropped during PTL out due to an asymptomatic LVEF decline.&#x2028; Discussion: L at 1000 mg/day is not feasible combined w/ weekly P and T by protocol stipulation (&gt; 20% pts required L dose reduction) primarily due to excessive G 3 diarrhea. These results have led to the modification of Design 2 (Arm D) of ALTTO. We will report updated results.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2108.

Pharmacokinetics and tolerability of exemestane in combination with raloxifene in postmenopausal women with a history of breast cancer

PURPOSE

Raloxifene is a second-generation selective estrogen receptor modulator that reduces the incidence of breast cancer in postmenopausal women. Exemestane, a steroidal aromatase inhibitor, decreases contralateral new breast cancers in postmenopausal women when taken in the adjuvant setting. Preclinical evidence suggests a rationale for coadministration of these agents to achieve complete estrogen blockade.

EXPERIMENTAL DESIGN

We tested the safety and tolerability of combination exemestane and raloxifene in 11 postmenopausal women with a history of hormone receptor-negative breast cancer. Patients were randomized to either raloxifene (60 mg PO daily) or exemestane (25 mg PO daily) for 2 weeks. Patients then initiated combination therapy at the same dose levels for a minimum of 1 year. Pharmacokinetic and pharmacodynamic data for plasma estrogens, raloxifene, exemestane, and their metabolites were collected at the end of single-agent therapy and during combination therapy.

RESULTS

Plasma concentration-time profiles for each drug were unchanged with monotherapy versus combination therapy. Raloxifene did not affect plasma estrogen levels. Plasma estrogen concentrations were suppressed below the lower limit of detection by exemestane as monotherapy and when administered in combination with raloxifene. The most common adverse events of any grade included arthralgias, hot flashes, vaginal dryness and myalgias.

CONCLUSIONS

In this small study, coadministration of raloxifene and exemestane did not affect the pharmacokinetics or pharmacodynamics of either agent to a significant degree in postmenopausal women. The combination of estrogen receptor blockade and suppression of estrogen synthesis is well tolerated and warrants further investigation.

Adjuvant (adj) bevacizumab (B) plus dose-dense (dd) doxorubicin/cyclophosphamide (AC) followed by nanoparticle albumin- bound paclitaxel (nab-p) in early stage breast cancer (BC) patients (pts): Cardiac safety

567

Background: Dose dense, q2 wk AC-paclitaxel (T) is superior to q3 wk therapy (Rx) (Citron, JCO 2003). The risk of congestive heart failure (CHF) with ddAC-T is not increased at <1%. In MBC, B improves PFS when added to T (Miller, SABCS 2005). It is unclear if doxorubicin plus B increases risk of CHF. Hence, we are testing the cardiac safety of ddAC-nab-p with concurrent B as adj therapy. Based upon the accepted cardiac event (CE) rate of ≤4% in trials with adj trastuzumab (an agent with known cardiac toxicity), we designed this study with similar monitoring & tolerability thresholds. The primary endpoint is cardiac safety, defined as discontinuation of B due to cardiac death from LV dysfunction or symptomatic CHF (dyspnea and LVEF<50%). Secondary endpoints: toxicity, disease-free & overall survival. Methods: Eligible pts have resected HER2(-) BC and normal LVEF. Rx consists of q2wk AC (60/600 mg/m2) ×4 then nab-p (260 mg/m2) x4 with pegfilgrastim on Day 2 plus B for one year (10mg/kg IV q2wk ×8 with chemoRx then B 15mg/kg q3wk); radiation & endocrine Rx per standard of care. MUGA obtained at baseline & mos. 2, 6, 9, 18. Pts with significant asymptomatic ↓LVEF during Rx may have B held per protocol. These pts are not counted as CEs but will have long-term cardiac monitoring. Accrual goal is 75 pts. If ≥3 CE (∼4.7%) or >1 cardiac death from LV dysfunction, B + ddAC-nab-p will not be considered safe. Results: 44 pts have enrolled, median (med) age 46.5 yrs (33–67). 28 pts have baseline & month 2 LVEF data: med baseline LVEF 68% (61–82), med LVEF at mo. 2 after ddAC+B 68% (53–75); 1 pt had an 18 point asymptomatic drop to 53% - B held but reinitiated in 4 wks with repeat LVEF 63%. 12 pts completed nab-p+B but none have reached the 6 mo. MUGA. Rx-related Gr 3/4 toxicity: neutropenia gr4 (6.8%), diarrhea gr3 (2.3%), hypertension gr3 (2.3%), neuropathy gr 3 (2.3%), fatigue gr 3 (2.3%), mucositis gr 3 (2.3%). 4 pts have withdrawn from study Rx, but only 1 due to toxicity including gr3 fatigue, mucositis & neuropathy. Conclusions: No LV dysfunction has been observed with B + ddAC-nab-p; this trial is on-going. Long-term follow-up and analysis of troponin, renin and circulating endothelial & tumor cells are planned.

No significant financial relationships to disclose.

Randomized phase II trial of three dosing schedules of nanoparticle albumin-bound paclitaxel with bevacizumab as first-line therapy for HER2-negative metastatic breast cancer: An initial interim safety report

1104

Background: Nanoparticle paclitaxel (NP) at 260mg/m2 every 3 weeks (q3wk) is more effective than standard paclitaxel (P) (Gradishar et al, JCO 2005). Weekly, uninterrupted administration of P is superior to q3wk P in MBC (Seidman et al, Proc ASCO 2004). When added to weekly P as 1st-line therapy for MBC, bevacizumab (B) improves response rate and progression-free survival (Miller et al, Proc ASCO 2005). We initiated a randomized phase II trial of NP given at 260mg/m2 q3wk (arm A) vs. 260mg/m2 q2wk with filgrastim (arm B) vs. 130mg/m2 weekly, all with B, as 1st-line therapy for patients (pts) with HER2- MBC. Methods: 66 of planned 225 pts have enrolled. After 31 pts had been randomized and treated, investigators concerned about possible differential neurotoxicity requested this early interim safety analysis. Median age is 54 (range 40–78). 83% are post-menopausal and 100% have visceral dominant disease. 68% had prior adjuvant or neo-adjuvant chemotherapy; 35% with taxanes. Results: With 170 cycles delivered (median: 4, range 1–15) 10 dose reductions have been necessary for NP (1 in A, 5 in B, 4 in C). No hypersensitivity reactions or dose interruptions have occurred for NP; 3 doses of B have been held due to hypertension. Significant preliminary antitumor activity has been noted in all arms. One grade 4 toxicity occurred in arm C, hyperglycemia. 15 grade 3 toxicities have been reported across all arms. Pts on arm A have experienced 3 grade 3 toxicities (30%): fatigue, neutropenia, and arthralgia with no grade 3 neurotoxicity. Pts on arm B have had 7 grade 3 toxicities (58%) with 3 pts experiencing grade 3 sensory neuropathy (25%) and others experiencing fatigue, neutropenia, anemia, esophagitis, dyspnea, and ataxia. 5 arm C pts experienced grade 3 toxicities (56%) including diarrhea, dehydration, mucositis, neutropenia, hypokalemia; 2 pts have had grade 3 sensory neuropathy (22%). Conclusions: This early safety analysis does not detect any statistically or clinically significant differences in grade 3 toxicity and all arms continue to accrue. The next protocol-specified safety analysis is expected in early 2007, with mature safety data for 60 pts. Updated results will be presented.

[Table: see text]