Pembrolizumab for patients with advanced prostate adenocarcinoma: Preliminary results from the KEYNOTE-028 study

Abstract

Of the 23 pts enrolled in this cohort, median age was 65 years, 74% had an ECOG PS of 1 (1 pt had an ECOG PS of 2), and 74% received ≥2 prior therapies for metastatic disease. As of February 17, 2016, median follow-up duration was 33 wk (range, 6-79 wk). Fourteen pts (61%) had treatment-related adverse events (TRAEs), most commonly nausea (n = 3, 13%). Three pts (13%) had grade 3-4 TRAEs; 1 pt had grade 3 fatigue, 1 pt had grade 3 peripheral neuropathy, and 1 pt had grade 3 asthenia and grade 4 lipase increase. No pts died or discontinued pembrolizumab because of a TRAE. Three pts had a confirmed PR, for an ORR of 13% (95% CI, 3%-34%); median duration of response was 59 wk (range, 28-62 wk). Stable disease rate was 39% (n = 9; 95% CI, 20%-61%). Median OS was 8 mo, and the 6-mo PFS rate was 39%. Two pts remained on treatment at data cutoff. Exploratory assessment of the relationship between GEP score and clinical outcome revealed the putative T cell inflamed signature to be associated with better clinical outcome, consistent with pembrolizumab findings published previously.