A Phase Ib Study of Pembrolizumab as Second-Line Therapy for Chinese Patients With Advanced or Metastatic Melanoma (KEYNOTE-151)

Pembrolizumab shows robust antitumor activity and favorable safety in metastatic melanoma. KEYNOTE-151 evaluated pembrolizumab in Chinese patients, who have more aggressive melanoma subtypes than other populations. Chinese patients aged ≥18 years with advanced melanoma previously treated with one line of therapy received pembrolizumab 2 mg/kg every 3 weeks for 35 cycles or until confirmed disease progression, intolerable toxicity, or study withdrawal. Primary end points were objective response rate (ORR) per RECIST v1.1 by blinded independent central review and safety. Key secondary end points included duration of response (DOR) and progression-free survival (PFS) per RECIST v1.1 and overall survival (OS). Median age was 52 years (N = 103); 37.9% had acral and 14.6% had mucosal melanoma. Median follow-up was 7.9 months at data cutoff (December 27, 2017). ORR was 16.7% (95% CI, 10.0–25.3%) (1 complete, 16 partial responses). Disease control rate was 38.2%. ORR was 15.8% for acral, 13.3% for mucosal melanoma. Median DOR was 8.4 months; 65.6% of patients had response duration ≥6 months. Median PFS was 2.8 months (95% CI, 2.7–3.5 months); 6-month rate was 20.4%. Median OS was 12.1 months (95% CI, 9.6 months–not reached); 6-month rate, 75.7%; 12-month rate, 50.6%. Treatment-related AEs (TRAEs) occurred in 87 (84.5%) patients; 9 (8.7%) experienced grade 3/4 TRAE and 2 (1.9%) discontinued because of TRAE; none died. Two deaths occurred that were unrelated to treatment. Pembrolizumab was well tolerated and provided clinically meaningful antitumor activity as second-line therapy in Chinese patients with advanced melanoma.