Associations with response to Poly(ADP-ribose) Polymerase (PARP) inhibitors in patients with metastatic breast cancer

PARP inhibitors (PARPi) have modest antitumor activity in patients with advanced breast cancer and mutation in BRCA. It is unclear whether some subgroups derive greater benefit from treatment. MEDLINE and EMBASE were searched from inception to March 2021 to identify trials of PARPi in patients with metastatic breast cancer. Objective response rate (ORR) and clinical benefit rate (CBR) to PARPi were extracted and pooled in a meta-analysis using the Mantel Haenszel random effects model. Meta-regression explored the influence of patient and tumor characteristics on ORR and CBR. For randomized trials, hazard ratio comparing PARPi to control therapy were pooled using inverse variance and random effects. Analysis included 43 studies comprising 2409 patients. Among these, 1798 (75%) patients had BRCA mutations and 1146 (48%) were triple negative. In 10 studies (28%; n = 680 patients), the PARPi was given in combination with platinum-based chemotherapy. Weighted mean ORR was 45%; 64% when combined with platinum vs 37% with PARPi monotherapy (p < 0.001). Previous platinum-based chemotherapy was associated with lower ORR (p = 0.02). Compared to standard chemotherapy, progression-free survival was improved (HR 0.64, p < 0.001), but there was no difference in overall survival (HR 0.87, p = 0.06). There were no differences in ORR or CBR between BRCA1 and BRCA2 mutations. PARPi are more active in combination with platinum than as monotherapy, with lower response if given as monotherapy after platinum exposure. Significant improvements in ORR translated to modest improvement in progression-free, but not overall survival. There was no association between ORR and BRCA mutations.

Association between global longitudinal strain and cardiopulmonary fitness in patients with breast cancer

Background

Anthracycline and trastuzumab therapies improve survival in the cancer population, but are limited by treatment induced cardiotoxicity. Echocardiography derived global longitudinal strain (GLS) permits more sensitive detection of cardiotoxicity than left ventricular ejection fraction (LVEF). However, the clinical implication of a reduction in GLS in cancer survivors is unknown.

Purpose

To define the association between GLS and cardiopulmonary fitness in women with breast cancer immediately post cancer therapy.

Methods

Women with HER2+ early stage breast cancer (EBC, Stage I-III) receiving anthracyclines followed by trastuzumab were recruited prospectively and followed between January 2015 and December 2019 with echocardiography during therapy. Left ventricular peak systolic GLS (GE EchoPAC, 3 apical views) and 3D-LVEF were measured prior to anthracyclines, and after completion of trastuzumab at 12 months. Exercise capacity was measured using a supine bicycle cardiopulmonary exercise test. Results of exercise testing at end of treatment were compared between patients with and without reduced GLS (absolute value ≤18% vs &gt;18%) at the end of therapy.

Results

Amongst 128 women, 43 (34%) had a GLS ≤18% at the end of trastuzumab therapy. Baseline patient demographics including tumor characteristics and cardiac risk factors were similar between those with normal and abnormal GLS. During treatment 33 (25.8%) participants developed cardiotoxicity defined by the CREC criteria based on 3D-LVEF. Significant baseline (pre-cancer treatment) differences were found between groups for GLS (GLS 21.2±1.8 vs 19.6±2.2, p&lt;0.001) and 3D LVEF (61.8±3.5 vs 60.2±3.7%, p=0.02) for those with GLS &gt;18% and GLS ≤18% respectively at the completion of trastuzumab. Compared to those with GLS &gt;18% those with GLS ≤18% had lower VO2peak (17.4±3.8 mL.kg-1.min-1 versus 20.2±4.9 mL.kg-1.min-1, p=0.001) despite similar effort (respiratory exchange ratio 1.14 versus 1.12, p=0.30). GLS following therapy (β coefficient: −0.596, SE 0.255; p=0.02) and age (β coefficient: −0.115, SE 0.057; p=0.047) were the only parameters associated with VO2peak after adjusting for relevant confounding factors.

Conclusion

A significant proportion of women receiving cancer therapy for HER2+ EBC had reduced GLS at end of treatment. Abnormal GLS at the end of cancer treatment was associated with lower VO2peak. Reduced VO2peak is strongly associated with late-occurring cardiovascular events and should prompt closer cardiac monitoring, cardiac risk factor management, and referral to exercise rehabilitation programs.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Canadian Institute of Health Research

Abstract P4-14-03: Influence of competing risks of death on the interpretation of adjuvant endocrine therapy trials for breast cancer

Background: Early stage, hormone sensitive breast cancer is associated generally with a good prognosis, with only a minority of patients expected to die of breast cancer. Death from causes other than breast cancer can dilute the patients at risk of breast cancer events and result in over-estimation of risk of recurrence and consequently the benefit from breast cancer therapy, a so-called immortal time bias. The MA.17R trial (Goss et al 2016) evaluated the role of extending adjuvant treatment with letrozole from 5 to 10 years. Here we determine the effect of analyzing the MA.17R trial using methods accounting for competing risks.

Methods: We compared conventional and competing risk methods for disease-free survival (DFS) and for distant recurrence-free survival (DRFS). In Kaplan-Meier analyses death from any cause was considered an event while cumulative incidence functions (CIFs) assumed death without recurrence to be a competing risk. The complement of the survival function (one minus the survival function) was used to estimate incidence of the primary event of interest. This was compared to estimates obtained using CIFs accounting for the occurrence of competing events.

Results: Non-breast cancer death was the most common event defining DFS and DRFS. Over the course of follow-up, there was increasing discrepancy between the risk of disease recurrence measured using Kaplan-Meier and CIF. Among letrozole treated patients the estimated distant recurrence at 5 years of follow-up was 5.4% using CIF and 9.6% using Kaplan-Meier. At 10 years of follow-up, the estimated distant recurrence was 8.4% using CIF and 20.0% using Kaplan-Meier. Similar results were observed for the placebo group (8.5% vs 12.1% at 5 years and 14.8% vs 27.3% at 10 years), and in patients with baseline cardiovascular disease (see Table). Benefit from letrozole on DFS and DRFS was greater when accounting for competing risk (hazard ratio [HR] for DFS 0.66, 95%CI 0.48-0.90; DFRS HR 0.75, 0.50-1.14) compared to the conventional method (DFS HR 0.79, 0.62-0.99; DRFS HR 0.91, 0.70-1.18). In women with baseline cardiovascular risk, the benefits of extended adjuvant letrozole when considering competing risk (DFS HR 0.38, 0.16-0.89; DRFS HR 0.46, 0.16-1.35) were also greater than those observed in the conventional analysis (DFS HR 0.55, 0.32-0.93; DRFS HR 0.59, 0.33-1.04). Treatment with extended letrozole did not influence non-breast cancer death in women who died with disease recurrence (HR 1.06, 0.74 -1.50) or in those with competing risk or censored from the analysis (HR 1.05, 0.73 -1.49).

Conclusion: Over the course of follow-up, estimates of DFS and DRFS differ increasingly if measured using Kaplan-Meier or CIF, with CIF estimates of risk being substantially lower. Using a competing risk model, the reduction in distant recurrence at 8 years with extended letrozole is less than 1%. Additional competing risk analyses of the MA.17 (Goss 2006) and MA.27 (Goss 2013) trials are ongoing.

Cumulative incidence of disease recurrence in patients with baseline cardiovascular riskTime (years)CIF (%)1-KM (%)Letrozole11.51.534.46.555.813.8Placebo13.53.538.311.8512.520.3

Citation Format: Ethier J-L, Parulekar W, Shepherd L, Summers L, Strasser-Weippl K, Tu D, Amir E. Influence of competing risks of death on the interpretation of adjuvant endocrine therapy trials for breast cancer [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 P4-14-03.

Outcomes of single versus double hormone receptor-positive breast cancer. A GEICAM/9906 sub-study

BACKGROUND

Retrospective data suggest better outcomes for patients with double hormonal receptor (oestrogen [ER] and progesterone receptor [PgR])-positive (dHR+) early breast cancer, compared with single hormonal receptor-positive, sHR+, (ER+/PgR- or ER-/PgR+) disease. Here, we evaluate the classification according to intrinsic subtypes and clinical outcomes of sHR+ versus dHR+ in HER2-negative breast cancer patients enrolled in GEICAM/9906 study (NCT00129922).

METHODS

Archival tumours were retrieved retrospectively for the analysis of ER, PgR and HER2 status and classified into intrinsic subtypes using the PAM50 gene expression assay. Disease-free survival (DFS) and overall survival (OS) were explored using a Cox proportional hazard analysis.

RESULTS

Data on intrinsic subtypes were available in 571 (50%) patients with ER+ and/or PR+, and HER2-negative primary tumours. The incidence of luminal A and luminal B subtypes were 52%/36% in dHR+ tumours (ER+/PgR+), and 15%/58% in ER+/PgR-tumours. ER-/PgR+ tumours were mainly luminal A (52%). Compared with ER+/PgR+ patients, DFS was similar in ER-/PgR+ (hazard ratio [HR] 1.15, 95% confidence interval [CI] 0.57-2.34, p = 0.70) but worse in ER+/PgR- patients (HR 1.60, 95% CI 1.12-2.28, p < 0.01). Similar results were observed for OS (HR 1.50, p = 0.30 and HR 1.86, p < 0.01, respectively).

CONCLUSIONS

The ER+/PgR- group is characterised by higher proliferation and worse outcomes. In spite of the ER-/PgR+ subgroup resembles ER+/PgR+ disease in terms of molecular subtypes and outcomes, the small number of patients in this subgroup prevents from drawing any conclusions.

TRIAL REGISTRATION

EudraCT: 2005-003108-12 (retrospectively registered 28/06/2005). CLINICALTRIALS.

GOV IDENTIFIER

NCT00129922 (retrospectively registered 10/08/2005).

Abstract P3-17-02: Influence of non-measurable disease on progression-free survival in patients with metastatic breast cancer

Background:

Progression free-survival (PFS) is the dominant endpoint in phase 3 randomized controlled trials (RCTs) in women with metastatic breast cancer (MBC), and requires the ability to measure target lesions. It is unknown whether treatment effect on PFS is consistent among patients with measurable and non-measurable disease.

Methods:

We searched MEDLINE, EMBASE and COCHRANE for phase 3 RCTs in MBC that reported outcomes in subgroups with non-measurable (or bone only disease, if not reported explicitly) and measurable disease. Data were extracted and a single hazard ratio (HR) and 95% confidence intervals (CI) were computed to compare the individual trial treatment effect in non-measurable versus measurable disease. Data were then pooled in a meta-analysis. We repeated the analysis comparing bone only to non-bone only disease and performed subgroup analyses based on drug mechanism of action.

Results:

Of 82 RCTs that enrolled patients with non-measurable disease, 16 trials comprising 8516 patients were eligible for analysis. All included RCTs used PFS or time to progression as primary endpoints. There was no difference in pooled treatment effect between patients with non-measurable and measurable disease (HR 1.01, 95% CI 0.89-1.15, p=0.82). However, compared to non-bone only disease, a significantly greater effect on PFS was seen in those with bone only disease (HR 0.82, 95% CI 0.70-0.98, p=0.03). Subgroups analyses according to drug mechanism are shown in Table 1

Intra-study comparison, according to evaluated drug mechanismCohort/ Investigational drugNo. studies includedMeasurable HR (95% CI)Non measurable HR (95% CI)Intra- study comparison HR (95% CI)P – for intra-study comparisonAll160.69 (0.65-0.73)0.72 (0.64-0.80)1.01 (0.89-1.15)0.82Chemotherapy30.99 (0.87-1.13)0.67 (0.44-1.02)0.73 (0.44-1.21)0.22Endocrine treatment40.86 (0.77-0.96)0.94 (0.80-1.10)1.13 (0.92-1.40)0.23Signal transduction inhibitors40.52 (0.48-0.57)0.41 (0.33-0.50)0.74 (0.59-0.94)0.01Anti-angiogenetic agents50.66 (0.59-0.73)0.84 (0.67-1.04)1.34 (1.05-1.71)0.02CI- confidence interval, HR- hazard ratio

. Compared to patients with measurable disease, there was a greater effect on PFS in those with non-measurable disease in RCTs of signal transduction inhibitors and endocrine therapy (HR 0.74, 95% CI 0.59-0.94, p=0.01). There was a lesser effect on PFS in patients with non-measurable disease in RCTs of antiangiogenic drugs (HR 1.34, 95% CI 1.05-1.71, p=0.02). Comparable effect on PFS was shown in RCTs evaluating endocrine therapy and chemotherapy.

Conclusions:

There is variability in treatment effect on PFS in patients with measurable and non-measurable disease. There is greater effect on PFS in RCTs of endocrine therapy and signal transduction inhibitors and in patients with bone only disease. Standardization of PFS determination in patients with non-measurable and bone only disease is warranted.

Citation Format: Goldvaser H, Ribnikar D, Fazelzad R, Seruga B, Templeton AJ, Ocana A, Amir E. Influence of non-measurable disease on progression-free survival in patients with metastatic 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 P3-17-02.

Abstract P3-12-04: Efficacy of extended adjuvant aromatase inhibitors in subgroups of women with early breast cancer

Background: Randomized trials (RCTs) have reported improvements in breast cancer outcomes from extending treatment with aromatase inhibitors (AIs) beyond the initial 5 years after diagnosis. It is uncertain whether this effect is consistent in different subgroups.

Methods: We identified RCTs that compared extended AIs to placebo or no treatment using a systematic search of MEDLINE. The search was supplemented by a review of abstracts from the American Society of Clinical Oncology and San Antonio Breast Cancer Symposium meetings between 2013 and 2016. Hazard ratios (HRs) and 95% confidence intervals (CI) for disease-free survival (DFS) were extracted or estimated from forest plots and included in a meta-analysis using generic inverse variance and random effects modelling. Pre-specified subgroups included age (&lt;60 ± 5 years vs. ≥60 ± 5 years), tumor size (≤2 cm vs. &gt;2 cm), nodal status (positive vs. negative), hormone receptor status (estrogen [ER] and progesterone receptor [PR] positive vs. ER or PR positive) and administration of adjuvant chemotherapy (yes vs. no).

Results: Seven trials comprising 16,349 patients were analyzed. Studies designs and prior endocrine therapy are shown in Table 1

Table 1: Characteristics of included studies.TrialTreatment ArmsSample sizePrior endocrine treatmentABCSG 6aAnastrozole 3 years vs. none387/ 469Tamoxifen± aminoglutethimide: 100%, 5 yearsMA 17Letrozole 5 years vs. placebo2572/ 2577Tamoxifen: 100%, ∼5 yearsNSABP B-33Exemestane 5 years vs. placebo783/ 779Tamoxifen: 100%, ∼5 yearsDutch DATAAnastrozole 6 years vs,. anastrozole 3 years827/ 833Tamoxifen: 100%, 2-3 yearsIDEALLetrozole 5 years vs. letrozole 2.5 years903/ 898Any endocrine treatment (tamoxifen/AIs/sequence of tamoxifen+ AIs): 100%, 5 yearsMA.17RLetrozole 5 years vs. placebo959/ 959AIs: 100%, ∼5 years Prior tamoxifen: 79.3%NSABP B-42Letrozole 5 years vs. placebo1959/ 1964Any endocrine treatment (AIs/sequence of tamoxifen+ AIs): 100%, 5 years

. The pooled effect of prolonged treatment with AIs in different subgroups is shown in the Table 2.

Table 2: Intra-subgroup comparison of longer AIs treatment effect by subgroupsSubgroup ASubgroup BHR (95% CI) Subgroup AHR (95% CI) Subgroup BP for differenceAge &lt;60 ± 5Age ≥60 ± 50.83 (0.70-0.99)0.85 (0.74-0.97)0.64T &gt;2 cmT ≤2 cm0.77 (0.55-1.06)0.88 (0.68-1.13)0.44N positiveN negative0.72 (0.63-0.83)0.83 (0.64-1.08)0.22ER and PR positiveER or PR positive0.68 (0.44-1.04)1.03 (0.53-2.02)0.27Adjuvant chemotherapyNone0.71 (0.59-0.86)0.80 (0.65-0.98)0.51

Overall, the effect of prolonged AIs was similar in all subgroups. However, non-significantly greater effect sizes were seen in patient with larger tumors, nodal involvement, presence of both ER and PR expression and those treated with adjuvant chemotherapy.

Conclusions: Extended treatment with adjuvant AIs is associated with similar relative improvements in DFS in all subgroups analyzed. The greater effect size seen in node positive and large tumor subgroups and the higher baseline risk of recurrence will likely translate to a higher absolute benefit from extended AIs in these groups.

Citation Format: Goldvaser H, Algorashi I, Ribnikar D, Majeed H, Ocana A, Seruga B, Templeton AJ, Amir E. Efficacy of extended adjuvant aromatase inhibitors in subgroups of women with early 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 P3-12-04.

Interventions for preventing cardiomyopathy due to anthracyclines: a Bayesian network meta-analysis

Background

The relative efficacy of interventions for primary prevention of anthracycline-associated cardiotoxicity is unknown.

Methods

We conducted a systematic review of randomized controlled trials for primary prevention of anthracycline-associated cardiotoxicity in adult cancer patients. We used hierarchal outcome definitions in the following order of priority: (1) composite of heart failure or decline in left ventricular ejection fraction, (2) decline in ejection fraction, or (3) heart failure. Data were analyzed using a Bayesian network meta-analysis with random effects.

Results

A total of 16 trials reported cardiotoxicity as a dichotomous outcome among 1918 patients, evaluating dexrazoxane, angiotensin antagonists, beta-blockers, combination angiotensin antagonists and beta-blockers, statins, Co-enzyme Q-10, prenylamine, and N-acetylcysteine. Compared with control, dexrazoxane reduced cardiotoxicity with a pooled odds ratio (OR) of 0.26 (95% credible interval [CrI] 0.11-0.74) and had the highest probability (33%) of being most effective. No other agent was demonstrably better than placebo. Angiotensin antagonists had an 84% probability of being most effective in a sensitivity analysis excluding one outlying study (OR 0.06 [95% CrI 0.01- 0.24]). When the outcome was restricted to heart failure, dexrazoxane was associated with an OR of 0.12 (95% CrI 0.06-0.23) relative to control and had 58% probability of being most effective, while angiotensin antagonists had an OR of 0.18 (95% CrI 0.05-0.55). Available data suggested that dexrazoxane and angiotensin antagonists did not affect malignancy response rate or risk of death.

Conclusion

Moderate quality data suggest that dexrazoxane, and low quality data suggest angiotensin antagonists, are likely to be effective for cardiotoxicity prevention.

Impact of the pan-Canadian Oncology Drug Review on provincial concordance with respect to cancer drug funding decisions and time to funding

BACKGROUND

The pan-Canadian Oncology Drug Review (pcodr) was implemented in 2011 to address uneven drug coverage and lack of transparency with respect to the various provincial cancer drug review processes in Canada. We evaluated the impact of the pcodr on provincial decision concordance and time from Notice of Compliance (noc) to drug funding.

METHODS

In a retrospective review, Health Canada's Drug Product Database was used to identify new indications for cancer drugs between January 2003 and May 2014, and provincial formulary listings for drug-funding dates and decisions between 1 January 2003 and 31 December 2014 were retrieved. Multiple linear models and quantile regressions were used to evaluate changes in time to decision-making before and after the implementation of the pcodr. Agreement of decisions between provinces was evaluated using kappa statistics.

RESULTS

Data were available from 9 provinces (all Canadian provinces except Quebec), identifying 88 indications that represented 51 unique cancer drugs. Two provinces lacked available data for all 88 indications at the time of data collection. Interprovincial concordance in drug funding decisions significantly increased after the pcodr's implementation (Brennan-Prediger coefficient: 0.54 pre-pcodr vs. 0.78 post-pcodr; p = 0.002). Nationwide, the median number of days from Health Canada's noc date to the date of funding significantly declined (to 393 days from 522 days, p < 0.001). Exploratory analyses excluding provinces with incomplete data did not change the results.

CONCLUSIONS

After the implementation of the pcodr, greater concordance in cancer drug funding decisions between provinces and decreased time to funding decisions were observed.

Abstract P3-09-05: Clinical outcome of patients with advanced triple negative breast cancer with germline and somatic variants in homologous recombination gene

Background: Variants in homologous recombination (HR) genes other than BRCA1/2 may cause a BRCA-like phenotype triple negative breast cancer (TNBC), which includes the sensitivity to platinums and DNA repair inhibitors. Evaluation of HR proficiency may influence the clinical management of TNBC. Our aim was to evaluate germline and somatic HR gene variants in advanced TNBC patients (pts) and clinical outcome.

Methods: Our cohort included advanced TNBC pts unselected for family history or age at diagnosis, enrolled in an institutional molecular screening program (NCT01505400). DNA from matched blood and FFPE tumor samples was assessed using a lab developed next generation sequencing Hereditary Cancer Panel (NGS-HCP) that includes all exons of 52 cancer predisposition genes, with 20 HR genes (Illumina MiSeq/NextSeq, germline coverage 100x, somatic coverage 500x). Medical records were reviewed for clinical outcome, pathology and prior germline BRCA1/2 testing results. All pts consented for research on banked samples and return of pathogenic germline variants was optional. Log rank test was used to determine time from surgery with curative intent to relapse (TTR) and overall survival from diagnosis to death (OS) differences based on presence of HR variants.

Results: We included 32 pts who consented for return of pathogenic germline variants and had sufficient DNA for NGS-HCP analysis. Median age at diagnosis was 45 years (range 21-80). Initial stages at diagnosis were: I (12.5%), II (62.5%), III (19%) and IV (6%). Germline HR variants were detected in 17 pts (53%) with a median number of variants per patient of 1 (range 0-6). Five pts had likely pathogenic or pathogenic variants in HR genes: BRCA1 (2), BRCA2 (1) FANCC (1) and FANCC + BML (1). Another patient had a BRCA1 pathogenic variant previously detected by Multiplex Ligation-dependent Probe Amplification but was not detected by NGS-HCP. 26 variants of unknown significance (VUS) were identified in 13 HR genes, including FANCA (6), FANCF (3) and BRCA1 (3). Only one patient had a somatic HR variant in FANCA not found in the germline. 30 pts (94%) had somatic TP53 variants. Sporadic somatic BRCA1/2 variants were not seen. BRCA1/2 variants present in the tumor were equivalent to those detected in blood of BRCA1/2 carriers. Median (m) TTR was 17 months (range 1-119) and mOS was 49 months (range 8-123). Presence of likely pathogenic or pathogenic germline variants was not associated with TTR (p=0.78) and OS (p=0.23). Presence of germline VUS, likely pathogenic or pathogenic variants also did not correlate with TTR (p=0.72) and OS (p=0.47)

Conclusions: In our cohort of pts with advanced TNBC, 12% had germline pathogenic variants in BRCA1/2, similar to the previously reported rate in early stage TNBC pts. Prevalence of likely pathogenic or pathogenic variants in non-BRCA HR genes was 6%. The presence of germline variants in HR genes was not associated with clinical outcome, however, the number of patients included was small and we had limited power to detect survival differences.Background: Variants in homologous recombination (HR) genes other than BRCA1/2 may cause a BRCA-like phenotype triple negative breast cancer (TNBC), which includes the sensitivity to platinums and DNA repair inhibitors. Evaluation of HR proficiency may influence the clinical management of TNBC. Our aim was to evaluate germline and somatic HR gene variants in advanced TNBC patients (pts) and clinical outcome.

Methods: Our cohort included advanced TNBC pts unselected for family history or age at diagnosis, enrolled in an institutional molecular screening program (NCT01505400). DNA from matched blood and FFPE tumor samples was assessed using a lab developed next generation sequencing Hereditary Cancer Panel (NGS-HCP) that includes all exons of 52 cancer predisposition genes, with 20 HR genes (Illumina MiSeq/NextSeq, germline coverage 100x, somatic coverage 500x). Medical records were reviewed for clinical outcome, pathology and prior germline BRCA1/2 testing results. All pts consented for research on banked samples and return of pathogenic germline variants was optional. Log rank test was used to determine time from surgery with curative intent to relapse (TTR) and overall survival from diagnosis to death (OS) differences based on presence of HR variants.

Results: We included 32 pts who consented for return of pathogenic germline variants and had sufficient DNA for NGS-HCP analysis. Median age at diagnosis was 45 years (range 21-80). Initial stages at diagnosis were: I (12.5%), II (62.5%), III (19%) and IV (6%). Germline HR variants were detected in 17 pts (53%) with a median number of variants per patient of 1 (range 0-6). Five pts had likely pathogenic or pathogenic variants in HR genes: BRCA1 (2), BRCA2 (1) FANCC (1) and FANCC + BML (1). Another patient had a BRCA1 pathogenic variant previously detected by Multiplex Ligation-dependent Probe Amplification but was not detected by NGS-HCP. 26 variants of unknown significance (VUS) were identified in 13 HR genes, including FANCA (6), FANCF (3) and BRCA1 (3). Only one patient had a somatic HR variant in FANCA not found in the germline. 30 pts (94%) had somatic TP53 variants. Sporadic somatic BRCA1/2 variants were not seen. BRCA1/2 variants present in the tumor were equivalent to those detected in blood of BRCA1/2 carriers. Median (m) TTR was 17 months (range 1-119) and mOS was 49 months (range 8-123). Presence of likely pathogenic or pathogenic germline variants was not associated with TTR (p=0.78) and OS (p=0.23). Presence of germline VUS, likely pathogenic or pathogenic variants also did not correlate with TTR (p=0.72) and OS (p=0.47)

Conclusions: In our cohort of pts with advanced TNBC, 12% had germline pathogenic variants in BRCA1/2, similar to the previously reported rate in early stage TNBC pts. Prevalence of likely pathogenic or pathogenic variants in non-BRCA HR genes was 6%. The presence of germline variants in HR genes was not associated with clinical outcome, however, the number of patients included was small and we had limited power to detect survival differences.

Citation Format: Stjepanovic N, Kim RH, Wilson M, Mandilaras V, Berman H, Amir E, Cescon D, Elser C, Randall Armel S, McCuaig J, Volenik A, Demsky R, Chow H, Misyura M, Wang L, Oza AM, Kamel-Reid S, Stockley T, Bedard PL. Clinical outcome of patients with advanced triple negative breast cancer with germline and somatic variants in homologous recombination gene [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 P3-09-05.

Abstract P1-01-01: Circulating tumor cell number and CTC-endocrine therapy index predict clinical outcomes in ER positive metastatic breast cancer patients: Results of the COMETI Phase 2 trial

Introduction: Only half of hormone receptor positive (HR+) metastatic breast cancer (MBC) patients (pts) benefit from endocrine therapy (ET). Circulating tumor cells (CTC) are prognostic in pts with MBC using CellSearch® technology. The CTC-endocrine therapy index (CTC-ETI) provides semi-quantitative analyses of CTC-ER (estrogen receptor), BCL2, HER2, and Ki67 expression. We hypothesized that CTC-ETI high (elevated CTC number and/or low expression of ER and BCL2, and high expression of HER2 and Ki-67) might predict resistance to ET in a prospective, multi-institutional clinical trial: COMETI-P2-2012.0 (NCT01701050).

Methods: 121 pts with ER+, HER2 negative (-), and progressive MBC after one or more lines of ET or within 12 months (mos) of completing adjuvant ET, who were initiating a new ET, were enrolled after informed consent. CTC and CTC-ETI were determined as previously reported (Paoletti C et al, CCR 2015) at baseline (BL), 1, 2, 3, and 12 mos, and/or at the time of progression. Imaging was performed every 3 mos. Association of CTC levels and CTC-ETI with patient outcomes (progression free survival (PFS); rapid progression (RP) defined as progression within 3 mos) was assessed using logrank and Fisher's exact tests. Trial design estimated 85 PFS and 51 RP events, providing &gt;90% power (2-sided a=0.05); pts with unsuccessful BL CTC-ETI or ineligible were unevaluable. Only baseline (BL) data are reported in this abstract.

Results: 32% of enrolled pts had progression within 12 mos of completing adjuvant ET, whereas 40%, 20%, and 8% had 1, 2, ≥3 lines of ET for MBC. CTC-ETI was successfully determined in 93% of pts (90% CI, 88% to 97%). CTC were ≥5 CTC/7.5 ml whole blood in 37/108 (34%) pts evaluable for clinical validity. Elevated CTC was associated with worse PFS (median (m) PFS: 3.3 vs. 5.9 mos; P&lt;0.01). Low, intermediate, and high CTC-ETI were observed in 75 (69%), 6 (6%), and 27 (25%) pts, respectively. CTC-ETI was associated with PFS (logrank P&lt;0.01): pts with low, intermediate, and high CTC-ETI had mPFS of 5.7, 8.5, and 2.8 mos, respectively. In the 96 pts eligible for determination, elevated CTC was associated with RP, (65.6% vs. 42.2%; P=0.05) as was CTC-ETI (P=0.003): 79.2% (95% CI, 57.8% to 92.9%) of pts with high CTC-ETI had RP versus 41.2% (95% CI, 29.4% to 53.8%) with low CTC-ETI; in the small group with intermediate CTC-ETI 1 of 4 pts (25%) had RP.

Conclusions: In this multi-institutional, prospective study, CTC-ETI was accurately determined, confirming the previously established analytical validity of the assay, meeting the primary objective of the trial. Elevated CTC and CTC-ETI high compared to low were associated with poor outcomes to ET. CTC-ETI distribution resulted in a small number of patients assigned to the intermediate group, restricting our ability to associate this group with outcomes. These results suggest that CTC-biomarker phenotype and enumeration have clinical validity. CTC-ETI may identify ER+ HER2– MBC pts who are unlikely to benefit from ET and might be better treated with ET in combination with other therapies or proceed to chemotherapy. Further analyses including CTC-ETI at serial time points during ET are planned.

Citation Format: Paoletti C, Regan MM, Liu MC, Marcom PK, Hart LL, Smith II JW, Tedesco KL, Amir E, Krop IE, DeMichele AM, Goodwin PJ, Block M, Aung K, Cannell EM, Darga EP, Baratta PJ, Brown ME, McCormack RT, Hayes DF. Circulating tumor cell number and CTC-endocrine therapy index predict clinical outcomes in ER positive metastatic breast cancer patients: Results of the COMETI Phase 2 trial [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 P1-01-01.

Abstract P5-14-05: Capecitabine in early breast cancer: A meta-analysis of randomized controlled trials

Background

Capecitabine is an effective therapy for metastatic breast cancer. Its role in early breast cancer is uncertain due to conflicting data from randomized controlled trials (RCTs).

Methods

PubMed and major conference proceedings were searched to identify RCTs comparing standard chemotherapy (defined as cyclophosphamide/methotrexate/5-fluorouracil, anthracycline-based regimens or anthracycline/taxane combinations) with or without capecitabine in the neo-adjuvant or adjuvant setting. Hazard ratios (HR) for disease-free (DFS) and overall survival (OS), as well as odds ratios (ORs) for safety and tolerability were extracted or calculated and pooled in a meta-analysis. Subgroup analysis compared triple negative breast cancer (TNBC) to non-TNBC and whether capecitabine was given in addition to or in place of standard chemotherapy. Meta-regression was used to explore the influence of TNBC on OS.

Results

Eight studies comprising 9302 patients were included. In unselected patients, capecitabine did not influence DFS (HR 0.99, p=0.93) or OS (HR 0.90, p=0.36). There was a significant difference in DFS when capecitabine was given in addition to, compared to in place of standard treatment (HR 0.92 vs. 1.62, interaction p=0.002). Addition of capecitabine to standard chemotherapy was associated with significantly improved DFS in TNBC vs non-TNBC (HR 0.72 vs. 1.01, interaction p=0.02). Meta-regression confirmed this association with OS (R=-0.967, p=0.007). Capecitabine increased Grade 3/4 diarrhea (OR 2.33, p&lt;0.001) and hand foot syndrome (OR 8.08, p&lt;0.001), and resulted in more frequent treatment discontinuation (OR 3.80, p&lt;0.001).

Conclusion

Adding capecitabine to standard chemotherapy appears to improve DFS and OS in TNBC, but increases adverse events in keeping with its known toxicity profile. Consideration of this treatment is warranted, especially in high-risk patients.

Citation Format: Natori A, Ethier J-L, Amir E, Cescon DW. Capecitabine in early breast cancer: A meta-analysis of randomized controlled trials [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 P5-14-05.