1109P Second-line pembrolizumab (pembro) in Chinese patients (pts) with advanced melanoma: Long-term follow-up of the phase I KEYNOTE-151 study

At the 3-y follow-up of KEYNOTE-151 (NCT02821000), second-line pembro showed manageable safety and clinically meaningful antitumor activity in Chinese pts with advanced melanoma. Results from more than 5 y of follow-up are presented. Adults who had histologically confirmed locally advanced or metastatic melanoma, who were of Chinese descent, and whose disease progressed with first-line therapy received pembro 2 mg/kg IV Q3W for ≤35 cycles (∼2 y) or until disease progression or unacceptable toxicity. Pts with SD or better who discontinued pembro could receive a second course of pembro (≤17 cycles) upon disease progression. Primary end points were safety and tolerability and ORR per RECIST v1.1 by blinded independent central review (BICR). Secondary end points were DOR and PFS per RECIST v1.1 and irRECIST by BICR, ORR per irRECIST by BICR, and OS. Safety and OS were analyzed in pts who received ≥1 dose of pembro. Other efficacy end points were assessed in pts who received ≥1 dose of pembro and had measurable disease per RECIST v1.1 at baseline. One hundred three pts received pembro (102 with measurable disease at baseline). Median age was 52 y, 57.3% of the pts were female, 51.5% had PD-L1 positive disease, and 14.6% had mucosal melanoma. Median follow-up at data cutoff (Nov 30, 2022) was 73.2 mo (IQR, 67.6-74.8). No new safety signals were reported. Grade 3-5 treatment-related AEs occurred in 12.6% of pts; no pts died of treatment-related AEs. ORR per RECIST v1.1 was 17.6% (95% CI, 10.8-26.4; 1 CR, 17 PR); DCR was 38.2% (95% CI, 28.8-48.4). Median DOR per RECIST v1.1 was 13.8 mo (range, 2.7-69.4+); an estimated 37.7% of pts had DOR ≥60 mo. Median PFS was 2.8 mo (95% CI, 2.7-3.5); 60-mo PFS was 5.0%. One additional pt had PR per irRECIST (ORR, 18.6%; 95% CI, 11.6-27.6). Median OS was 13.2 mo (95% CI, 10.4-16.5); 60-mo OS was 13.4%. One pt with PR as the best overall response per RECIST v1.1 received second-course pembro. After more than 5 y of follow-up, second-line pembro continued to show manageable safety and clinically meaningful antitumor activity in Chinese pts with advanced melanoma. These results support the continued use of pembro in this population.