Citations

Abstract Purpose: Preplanned exploratory analyses were performed to identify biomarkers in circulating tumor cells (CTC) predictive of response to the topoisomerase 1 inhibitor etirinotecan pegol (EP). Experimental Design: The BEACON trial treated patients with metastatic breast cancer (MBC) with EP or treatment of physician's choice (TPC). Blood from 656 of 852 patients (77%) was processed with ApoStream to enrich for CTCs. A multiplex immunofluorescence assay measured expression of candidate response biomarkers [topoisomerase 1 (Top1), topoisomerase 2 (Top2), Ki67, RAD51, ABCG2, γH2AX, and terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling (TUNEL)] in CTCs. Patients were classified as Top1 low (Top1Lo) or Top1 high (Top1Hi) based on median CTC Top1 expression. Correlation of CTC biomarker expression at baseline, cycle 2 day 1 (C2D1), and cycle 4 day 1 with overall survival (OS) was investigated using Cox regression and Kaplan–Meier analyses. Results: Overall, 98% of samples were successfully processed, of which 97% had detectable CTCs (median, 47–63 CTCs/mL; range, 0–2,020 CTCs/mL). Top1, Top2, and TUNEL expression was detected in 52% to 90% of samples; no significant associations with OS were observed in pretreatment samples for either group. EP-treated patients with low C2D1Top1+ CTCs had improved OS compared with those with higher positivity (14.1 months vs. 11.0 months, respectively; HR, 0.7; P = 0.02); this difference was not seen in TPC-treated patients (HR, 1.12; P = 0.48). Patients whose CTCs decreased from Top1Hi to Top1Lo at C2D1 had the greatest OS benefit from EP (HR, 0.57; P = 0.01). Conclusions: CTC Top1 expression following EP treatment may identify patients with MBC most likely to have an OS benefit. Clin Cancer Res; 24(14); 3348–57. ©2018 AACR.

Abstract Background: Patients with previously untreated mTNBC typically receive cytotoxic chemotherapy as first-line therapy for metastatic disease. However, efficacy and safety are suboptimal. KEYNOTE-086 (NCT02447003) is a multicohort, single-arm, phase 2 study of pembrolizumab monotherapy for mTNBC. In cohort B, we assessed the safety and antitumor activity of pembrolizumab as first-line therapy for patients with PD-L1-positive mTNBC. Methods: Key eligibility criteria for cohort B were age ≥18 y, centrally confirmed TNBC, no prior systemic anticancer therapy for metastatic disease, ECOG performance status 0-1, measurable disease per RECIST v1.1 by central review, no radiographic evidence of brain metastases, and a tumor PD-L1 combined positive score (CPS) ≥1. Pembrolizumab 200 mg was given once every 3 wk for 24 mo or until disease progression, intolerable toxicity, or investigator or patient decision. Tumor imaging was performed every 9 wk for 12 mo and every 12 wk thereafter. Clinically stable patients with radiologic progression could remain on pembrolizumab until progression was confirmed on subsequent assessment. Primary end point was safety. Secondary end points included ORR, duration of response, and PFS (all RECIST v1.1 by central review) and OS. Results: Of the 206 patients with tumors evaluable for PD-L1 expression, 128 (62%) had PD-L1 CPS ≥1. Of these, 84 met all eligibility criteria and enrolled. All patients were women, median age was 52.5 y, 29 (35%) had ECOG PS 1, 40 (48%) had elevated LDH, 55 (65%) had visceral ± nonvisceral metastases, and 73 (87%) received prior (neo)adjuvant therapy. All patients received ≥1 pembrolizumab dose, and after median follow-up of 10.6 mo, 18 (21%) remained on pembrolizumab. Treatment-related AEs occurred in 53 (63%) patients and were of grade 3-4 severity in 7 (8%); no patients died or discontinued pembrolizumab because of treatment-related AEs. The most common treatment-related AEs were fatigue (26%), nausea (13%), and diarrhea (12%). No grade 3-4 treatment-related AE occurred in >1 patient. The most common immune-mediated AE was hypothyroidism (10%). Three patients had complete response and 16 had partial response for an ORR of 23% (95% CI 15-33). Of the 11 patients with a best response of stable disease, 1 had stable disease for ≥24 wk, leading to a disease control rate of 24% (95% CI 16-34). 12 of 19 (63%) responses were ongoing at data cutoff, and median duration of response was 8.4 mo (range 2.1+ to 13.9+). Median PFS was 2.1 mo (95% CI 2.0-2.2), with an estimated 6-mo PFS rate of 26%. Median OS was 16.1 mo (95% CI 11.3-NR), with an estimated 6-mo OS rate of 83%. Conclusions: Pembrolizumab monotherapy continues to demonstrate a favorable safety profile and robust, durable antitumor activity in patients with PD-L1-positive, previously untreated mTNBC. Citation Format: Adams S, Loi S, Toppmeyer DL, Cescon DW, De Laurentiis M, Nanda R, Winer EP, Mukai H, Tamura K, Armstrong AC, Liu MC, Iwata H, Ryvo L, Wimberger P, Rugo HS, Tan A, D'Aquanno C, Ding Y, Karantza V, Schmid P. KEYNOTE-086 cohort B: Pembrolizumab monotherapy for PD-L1–positive, previously untreated, metastatic triple-negative breast cancer (mTNBC) [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 PD6-10.

Abstract Background: Patients with breast cancer (BC) and chest wall disease have limited treatment options. We hypothesize that checkpoint inhibition may be an effective treatment approach due to the inflammatory nature of chest wall infiltration, and the association of PD-1 expression with lymphocytic infiltration. Platinum chemotherapy may facilitate anti-tumor immunity in a synergistic manner, and clinical studies of the PD-1 inhibitor pembrolizumab with platinum combinations have been effective in the treatment of advanced lung cancer. In this study, we will evaluate the combination of carboplatin and pembrolizumab in BC patients with chest wall disease. Methods: This is a randomized phase II multicenter study in the TBCRC including patients with advanced, unresectable BC with hormone resistant or triple negative chest wall disease. Patients may have had prior surgery, prior chest wall radiation is not required, and other sites of distant metastases are allowed. Eighty-four patients at TBCRC sites will be randomized 2:1 to receive pembrolizumab and carboplatin (n=56, Arm A) or carboplatin alone (n=28, Arm B) until disease progression. Patients randomized to Arm B may cross-over following progression to pembrolizumab alone (Arm Bx). Patients in Arm A will be treated with pembrolizumab 200 mg IV and carboplatin AUC 5 IV every 3 weeks for at least 6 cycles followed by maintenance pembrolizumab 200 mg IV every 3 weeks if stable or responding disease. Patients in Arm B will be treated with carboplatin AUC 5 IV every 3 weeks until progression, then may cross-over to pembrolizumab 200 mg IV every 3 weeks alone (Arm Bx). An interim analysis for futility will be performed after 18 patients are enrolled into Arm B to allow early closure of that arm for lack of efficacy. The primary endpoint is disease control rate at 18 weeks of treatment; the study is powered to detect a 20% difference in disease control rates between arms (hazard ratio 0.52, α= 0.10, β= 0.20). Secondary endpoints include progression free survival, toxicity, and response based on PD-L1 expression and irRECIST. Exploratory endpoints include association of response with a number of biomarkers including tumor PD-L1 gene expression, tumor and peripheral blood immune composition and cytokine expression, peripheral T-cell PD-1 expression, circulating tumor DNA, circulating tumor cells, and tumor MYC genomic expression using tumor biopsy and peripheral blood testing before and after treatment. This study should be open to accrual by August of 2017. (NCT03095352) Citation Format: Vidula N, Goga A, Krummel M, Hwang J, Liu M, Park BH, Nanda R, Pohlmann P, Storniolo AM, Van Poznak C, Brufsky A, Abramson V, Wolff A, Rugo HS. TBCRC 044: A randomized phase II study of pembrolizumab in combination with carboplatin versus carboplatin alone in breast cancer patients with chest wall disease [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 OT1-02-03.

Abstract Background: Pathological complete response (pCR) is accepted by FDA as a surrogate endpoint for accelerated approval of targeted agents in combination with chemotherapy based on better long-term outcomes compared to residual disease (Cortazar 2014). Methods: The multi-center, adaptively-randomized I-SPY2 platform trial uses pCR as the primary endpoint to identify investigational agents that will improve outcomes in women with stage 2/3 breast cancer with high risk of early recurrence, across all signatures, based on hormone receptor (HR), HER2, and 70-gene (MammaPrint) status. For patients with HR+ HER2- tumors, only 70-gene (Mammaprint) high-risk patients are enrolled. To date, 1200+ patients have been randomized to one of 14 arms: control (paclitaxel followed by AC); veliparib/carboplatin; neratinib; MK2206; trebananib; trastuzumab/pertuzumab; ado-trastuzumab emtansine/pertuzumab; pembrolizumabx4; ganitumab/metformin; ganetespib; PLX-3397. 7 agents graduated in at least one signature (> 85% probability of success in a 300-patient phase III confirmatory trial); 2 did not graduate; 1 stopped for toxicity, and 3 are enrolling (patritumab/trastuzumab, talazoparib/irinotecan, pembrolizumabx8). Local pathologists were centrally trained using the Residual Cancer Burden (RCB) assessment to ensure uniform evaluation and response classification; RCB 0 = pCR. Results: We evaluated the relationship between pCR and event free (EFS) and distant disease free survival (DDFS) in the first 522 pts (median follow-up:2.5 years). 180 pts achieved pCR (36%) while 338 did not (RCB=1-3). There were 82 EFS and 65 DRFS events. Over the entire group (including all arms), pCR was highly associated with 3-year EFS (p<0.001 for both). Pts achieving pCR had a 3% recurrence risk (RR) at 3 years; those with non-pCR had 24% RR over this time period. For distant recurrence, the 3-year RR with pCR was 2%, compared to 20% in pts with non-pCR. As expected, pCR rates varied by breast cancer subtype (HR+/HER2: 18% (35/196), HR+/HER2+: 40% (33/82), HR-/HER2+:68% (34/50), HR-/HER2-:41% (76/188)). The relationship between pCR and EFS was significant and clinically impactful within each subtype. 3-year survival (pCR group)Hazard Ratio OverallOverallHR+/HER2-HER2+TNBCEFS97%0.08 (0.03-0.23)0.14 (0.02-1.04)0 (NA)0.11 (0.03-0.37)DDFS98%0.08 (0.03-0.26)0.17 (0.01-1.23)0 (NA)0.09 (0.02-0.40) Conclusions: The first long-term efficacy results from the I-SPY2 TRIAL demonstrate that achieving pCR is a very strong surrogate endpoint for improved EFS and DDFS in a high-risk population, across all treatment arms, regardless of subtype. I-SPY2 shows substantially lower estimated EFS hazards for patients achieving pCR, compared to the 5 yr EFS hazard ratio for pCR vs not in Cortazar (hazard ratio 0.49), demonstrating important differences between a metaanalysis compared to a platform trial with uniform high-risk eligibility, standardized pathology assessment, and multiple targeted therapies. Our data support the use of pCR as a primary endpoint for accelerated approval of new drugs if EFS is evaluated in the same population. Based on these findings, the I-SPY2 TRIAL will test whether therapy can be deescalated or escalated for individual patients with the goal of achieving pCR for all. Citation Format: Yee D, DeMichele A, Isaacs C, Symmans F, Yau C, Albain KS, Hylton NM, Forero-Torres A, van't Veer LJ, Perlmutter J, Rugo HS, Melisko M, Chen Y-Y, Balassanian R, Krings G, Datnow B, Hasteh F, Tipps A, Weidner N, Zhang H, Tickman R, Thornton S, Ritter J, Amin K, Klein M, Chen B, Keeney G, Ocal T, Feldman M, Klipfel N, Sattar H, Mueller J, Gwin K, Baker G, Kallakury B, Zeck J, Duan X, Ersahin C, Gamez R, Troxell M, Mansoor A, Grasso LeBeau L, Sams S, Wisell J, Wei S, Harada S, Vinh T, Stamatakos MD, Tawfik O, Fan F, Adams A, Rendi M, Minton S, Magliocco A, Sahoo S, Fang Y, Hirst G, Singhrao R, Asare SM, Wallace AM, Chien AJ, Ellis ED, Han HS, Clark AS, Boughey JC, Elias AD, Nanda R, Korde L, Murthy R, Lang J, Northfelt D, Khan Q, Edmiston KK, Viscusi R, Haley B, Kemmer K, Zelnak A, Berry DA, Esserman LJ. Pathological complete response predicts event-free and distant disease-free survival in the I-SPY2 TRIAL [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 GS3-08.

Abstract Background: CALGB 40502/NCCTG N063H (Alliance) compared weekly NP or Ix to P; most patients received bevacizumab. Ix was inferior to P, and NP was not superior with a trend toward inferiority. Toxicity was increased in the experimental arms compared to P (Rugo et al, JCO 2015). We report long-term follow-up (FU) of this trial with an unplanned subset analysis in hormone receptor positive (HR+) and triple negative (TNBC) breast cancer. Methods: Patients were randomized 1:1:1 to receive P (90 mg/m2), Ix (16 mg/m2) or NP (150 mg/m2) on a 3 week (wk) on, 1 wk off schedule, stratified by prior adjuvant taxane use and hormone receptor status. B was initially given to all patients, but became optional in 3/2011 and was added to stratification. The primary endpoint was progression-free survival (PFS); secondary endpoints included safety and overall survival (OS). With a target N=900 patients, the study was powered to detect a hazard ratio of 1.36 (median PFS 10 vs 13.6 months). Eligibility included no prior chemotherapy for MBC, >12 mo from adjuvant P and measurable disease. Results: 799 patients were randomized between 11/08 and11/11 (283 to P, 271 to NP, 245 to Ix); 98% received bevacizumab. 68% (546) had HR+ disease, 25% (201) had TNBC. Median FU is 5 years. Median PFS is unchanged at 10.8, 9.2 and 7.4 mo for P, NP and Ix with hazard ratios (95% CIs) of 1.13 (0.94-1.34) and 1.44 (1.2-1.72) for NP and Ix to P, respectively. Median OS was 27.1, 24.2 and 23.6 months for P, NP and Ix with hazard ratios of 1.10 (0.91-1.34) and 1.3 (1.07-1.57) for NP and Ix to P, respectively. The effects of NP vs P on PFS and OS were significantly modified by subtype (interaction p=0.0018 and 0.0073), whereas Ix vs P was unchanged (interaction p's > 0.9, Table). More patients discontinued treatment due to adverse events in the experimental arms (14 vs 27 vs 23% for P, NP and Ix). Table P (mo)NP (mo)NP to P; HR (95% CI)Ix (mo)Ix to P, HR (95% CI)TNBC, PFS6.47.40.79 (0.55-1.12)15.61.39 (0.99-1.96)3HR+, PFS12.29.61.29 (1.04-1.59)181.5 (1.21-1.86)3TNBC, OS15.3210.74 (0.51-1.07)215.11.28(0.9-1.82)4HR+, OS33.226.61.25 (0.99-1.58)225.41.35(1.07-1.714Interaction tests: 1. p=0.0018; 2. p=0.0073; 3. p=0.96; 4. p=0.92 mo: months; HR: hazard ratio·· Conclusion: In patients with chemotherapy-naive MBC, Ix was inferior to P for PFS, and P was better tolerated than either NP or Ix. In this retrospective subset analysis, Ix and NP were inferior to P in HR+ disease, with a suggestion of improved PFS and OS with NP in patients with TNBC. Further investigation is required to explain and validate the subtype specificity seen in this exploratory analysis. Support: U10CA180820, U10CA180821, U10CA180882, U10CA180888. ClinicalTrials.gov Identifier: NCT00785291 Citation Format: Rugo HS, Barry WT, Moreno-Aspitia A, Lyss A, Huebner L, Mayer EL, Naughton M, Layman RM, Carey LA, Somer RA, Toppmeyer D, Velasco M, Perez EA, Hudis CA, Winer E. Long-term follow-up of CALGB 40502/NCCTG N063H (Alliance): A randomized phase III trial of weekly paclitaxel (P) compared to weekly nanoparticle albumin bound nab-Paclitaxel (NP) or ixabepilone (Ix) +/- bevacizumab as first-line therapy for locally recurrent or metastatic breast cancer (MBC) [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 GS3-06.

100 Background: Combining BEV with CT significantly improved progression-free survival (primary endpoint) in the E2100, AVADO, and RIBBON-1 trials in the 1st-line setting and the RIBBON-2 trial in the 2nd-line setting. Primary efficacy and safety results from RIBBON-2 have been published; here we present final OS results. Methods: Eligible patients (pts) had MBC that had progressed on 1st-line CT without BEV. 2nd-line CT (taxane, gemcitabine, capecitabine, or vinorelbine) was chosen before 2:1 randomization to CT with either BEV (10 mg/kg q2w or 15 mg/kg q3w) or PL continued until progression. Stratification factors were 2nd-line CT, hormone receptor status, and time from MBC diagnosis to 1st progression. All pts could receive BEV at progression. The primary endpoint was PFS. Final analysis of OS, a secondary endpoint, in the intent-to-treat population was planned after 557 events and provided 80% power to detect a hazard ratio (HR) of 0.77 (median OS increased from 14.0 to 18.2 months) at α=0.04. Results: At the time of data cutoff (Oct. 31, 2011), 184 (82%) of 225 pts in the CT/PL arm and 376 (82%) of 459 pts in the CT/BEV arm had died. BEV was administered in subsequent treatment lines in 12% vs 6% of pts, respectively. There was no difference in OS between treatment arms: HR 1.013 (95% CI 0.845–1.215), log-rank p=0.8843. Median OS was 17.8 months with CT/PL vs 18.6 months with CT/BEV. The 1-year OS rates were 69% vs 71%, respectively. Subgroup analyses by CT cohort showed HRs ranging from 0.86 (95% CI 0.58–1.29) in the capecitabine cohort (n=144) to 1.44 (95% CI 0.82–2.53) in the vinorelbine cohort (n=76). HRs were close to 1 for the two largest CT cohorts (taxane and gemcitabine). Exploratory analysis in the subgroup of patients with triple-negative MBC showed a HR of 0.85 (95% CI 0.58–1.26). Updated safety results were similar to those previously reported from the primary analysis. There were fewer fatal adverse events in the CT/BEV arm (1.5%) than in the CT/PL arm (3.2%). Conclusions: Final OS results from RIBBON-2 reveal no difference between treatment arms. No new safety signals were observed.