KEYNOTE-051: An update on the phase 2 results of pembrolizumab (pembro) in pediatric patients (pts) with advanced melanoma or a PD-L1–positive advanced, relapsed or refractory solid tumor or lymphoma.

10525Background: In the phase 1 portion of KEYNOTE-051 (NCT02332668), the 2-mg/kg-Q3W dose of pembro was identified as the pediatric recommended phase 2 dose. We provide an update on the safety and efficacy of this dose by tumor type in the ongoing phase 2 trial. Methods: Pts aged 6 mo to < 18 y with advanced melanoma or a PD-L1–positive, advanced relapsed/refractory solid tumor or lymphoma and measurable disease per RECIST v1.1 received pembro 2 mg/kg Q3W until confirmed disease progression per irRECIST by investigator review, intolerable toxicity, or pt/investigator decision to discontinue. Key efficacy end points were ORR and PFS per RECIST v1.1 by investigator and OS (data cutoff Oct 10, 2017). Results: 689 of 748 prescreened pts had PD-L1–evaluable tumors. Of these, 229 (33.2%) were PD-L1–positive; 125 pts (median age, 13 y [range, 1-17]) were enrolled and treated (10 Hodgkin lymphoma [HL]; 115 other tumors). Median follow-up was 5.7 mo (range, 0.2-29). Primary diagnoses were other non–central nervou...