KN100: Results from Japanese patients with advanced recurrent ovarian cancer treated with pembrolizumab monotherapy

Abstract

Abstract Background Interim results from the ongoing, 2-cohort, phase 2 KEYNOTE-100 study (NCT02674061) have suggested clinical efficacy of pembrolizumab (pembro) monotherapy in some patients (pts) with advanced ovarian cancer (AOC). Here, we present efficacy and safety results from Japanese pts in KEYNOTE-100. Methods Pts with epithelial AOC, fallopian tube cancer, or primary peritoneal cancer with prior treatment with debulking surgery followed by front-line platinum-based chemotherapy (CT) and documented disease recurrence were eligible for this study. Cohort A received ≤2 prior CT lines and had a platinum- or treatment-free interval (PFI; TFI) of 3-12 months. Cohort B received 3-5 prior CT lines and had a PFI/TFI of ≥ 3 months. All pts received pembro 200 mg every 3 weeks as monotherapy for 2 years or until progression, death, unacceptable toxicity, or consent withdrawal. The primary objectives were ORR per RECIST v1.1 by blinded independent central review for each cohort and by tumor PD-L1 expression. The relationship between PD-L1 expression (defined as combined positive score [CPS]) and ORR was assessed. Results In the second interim analysis (Matalounis, ASCO 2018) of the overall study population (N = 376), the ORR in Cohort A and B were 7% (95% CI, 5-11; n = 285) and 10% (95% CI, 5-18; n = 91), respectively. 21 Japanese pts were treated (19 in Cohort A; 2 in Cohort B). Mean (SD) age was 57 (10) years; 91% had ECOG PS 0, and 76% had stage 3-4 disease. The ORR in all pts was 19% (95% CI, 5-42). ORR increased with increasing PD-L1 expression: 25% (2/8) with CPS ≥1 and 50% (1/2) with CPS ≥10. 62% of pts had treatment-related adverse events (TRAEs), and 24% had grade 3-5 TRAEs. There were no treatment-related deaths in this subpopulation. Conclusion Pembro monotherapy was associated with antitumor activity in Japanese pts with recurrent AOC, with no new safety signals identified in this subpopulation. There was a potential trend associated with ORR and PD-L1 expression.