As treatment outcomes for mTNBC are poor, new treatment options are needed. We present a subgroup analysis for the safety and antitumor activity of pembrolizumab (PEM) as a therapy for Japanese patients (pts) with mTNBC in Cohorts A and B of KEYNOTE 086.
Pts with centrally confirmed mTNBC, at least one systemic treatment (Cohort A) or no prior systemic therapy (Cohort B) for metastatic disease, ECOG PS 0-1, and regardless of tumor PD-L1 expression (Cohort A) or with a tumor PD-L1 combined positive score (CPS) ≥1% (Cohort B), received PEM 200 mg IV every 3 weeks (wk) for 24 months (m) or until disease progression, intolerable toxicity, or investigator or patient (pt) decision. Tumor imaging was performed Q9W for 12 m and Q12W thereafter. Clinically stable pts with PD could remain on PEM until PD was confirmed on subsequent assessment. Primary endpoints were ORR (RECIST, central review) in Cohort A and safety in Cohorts A and B. Secondary were ORR in Cohort B, disease control rate (CR + PR + SD ≥ 24 wk), PFS and OS in Cohorts A and B.
Of 20 pts in Cohort A, 12 had PD-L1 (+) tumors and 8 had PD-L1 (-) tumors. The median age was 53.5 y, 11 pts had elevated LDH and 13 pts had visceral metastases. Of 9 pts in Cohort B, median age was 38.0 y, 1 pt had elevated LDH, 5 pts had visceral metastases. As of Nov 10, 2016, the best overall response was PR in 1 pt and SD in 2 pts in Cohort A, and CR in 1 pt and SD in 2 pts in Cohort B. Median PFS was 2.0 m (95% CI, 1.7 – 2.1) in Cohort A, and 2.1 m (95% CI, 1.6 – 4.2) in Cohort B. Median OS was 8.3 m (95% CI, 4.6 – 10.3) in Cohort A, and was not reached in Cohort B. Drug-related AEs (DRAEs) occurred in 20 pts (67.0%) in Cohorts A and B; the most common DRAEs were pruritus (4 pts), fatigue, pyrexia, anemia, rash, and diarrhea (3 pts each). Grade (Gr) 3-4 DRAEs were diarrhea, nausea, and bacteraemia (1 pt each), all in Cohort A. Infusion reaction (1 pt, Gr 2), interstitial lung disease (1 pt, Gr 1), hypersensitivity (1 pt, Gr 2) and hyperthyroidism (1 pt, Gr 1) were seen as irAE. No pts died or discontinued PEM due to AEs.
Data from 29 Japanese pts in Cohorts A and B suggest that PEM monotherapy has a well tolerated safety profile and anti-tumor activity which are similar to those reported in the overall populations.
NCT02447003.
Merck & Co., Inc., Kenilworth, NJ, USA
Merck & Co., Inc., Kenilworth, NJ, USA
H. Mukai: Received personal fees as honoraria from AstraZeneca, Novartis Pharma, Daiichi Sankyo, and Taiho Pharmaceutical, and received research funds from Chugai Pharmaceutical, Daiichi Sankyo, Eisai, Nippon Kayaku, Novartis Pharma, Pfizer Japan, and MSD.K.K. N. Masuda: Honoraria: Chugai, Astrazeneca. H. Ishiguro: Advisory board: MSD.K.K. T. Shimamoto, K. Yamamoto: Employees of MSD.K.K. Y. Ding, G. Aktan, V. Karantza: Employees of Merck
All other authors have declared no conflicts of interest.