Long-term outcomes in patients (pts) with ipilimumab (ipi)-naive advanced melanoma in the phase 3 KEYNOTE-006 study who completed pembrolizumab (pembro) treatment.

Abstract

9504 Background: Pembro demonstrated superior PFS and OS vs ipi in ipi-naive pts with advanced melanoma in the phase 3 KEYNOTE-006 study (NCT01866319). Here, we present long-term outcomes for all pts and in those pts who completed pembro therapy. Methods: Eligible pts (N = 834) were randomized 1:1:1 to pembro 10 mg/kg Q2W, pembro 10 mg/kg Q3W, or ipi 3 mg/kg Q3W for 4 doses. Treatment was continued for 2 yr (pembro only) or until disease progression, intolerable toxicity, or pt/investigator decision to discontinue. Per protocol, pts could interrupt pembro for ≤12 wk before discontinuation was required. Tumor imaging was performed at wk 12, then every 6 wk up to wk 48 and every 12 wk thereafter. After the prespecified final analysis, response assessments were per immune-related response criteria (irRC) by investigator review. Results: As of the data cutoff (Nov 3, 2016), median follow-up in the total population was 33.9 mo (range, 32.1-37.6). 33-mo OS rates were 50% in the pooled pembro arms (n = 556) and 39% in the ipi arm (n = 278); 33-mo PFS rates were 31% and 14%. ORR was 42% and 16%. Median duration of response was not reached for pembro (range 1.0+ to 33.8+ mo) or ipi (1.1+ to 34.8+ mo); 46 (68%) pembro-treated pts and 7 (58%) ipi-treated pts had a response lasting ≥30 mo. Among the 104/556 (19%) pts who completed pembro, median exposure to pembro was 24.0 mo (range 22.1-25.9). After a median follow-up of 9.0 mo after completion of pembro, 102 (98%) pts were alive. Responses were durable in pts who completed pembro; 9.7 mo after completion of pembro, estimated PFS (95% CI) was 91% (80-96) in all 104 pts, 95% (69-99) in pts with complete response (n = 24), 91% (74-97) in pts with partial response (n = 68), and 83% (48-96) in pts with stable disease (n = 12). Conclusions: Pembro provides durable efficacy after stopping the protocol-specified duration of treatment in pts with ipi-naive advanced melanoma in KEYNOTE-006. The estimated risk for progression or death nearly 10 mo after completing pembro is 9% and does not appear to differ by best response to pembro. Clinical trial information: NCT01866319.