Impact of antitumor activity on survival outcomes, and nonconventional benefit, with nivolumab (NIVO) in patients with advanced hepatocellular carcinoma (aHCC): Subanalyses of CheckMate-040.

475Background: NIVO (anti–PD-1 mAb) has demonstrated durable responses, long-term OS, and manageable safety in pts with aHCC in CheckMate-040 (El-Khoueiry, Sangro et al. 2017). With anti–PD-1 therapies, meaningful OS benefit may be seen even in pts who do not achieve a conventional response by RECIST v1.1. Here we report nonconventional benefit with NIVO and effect of antitumor activity on OS in sorafenib-experienced (sor-exp) pts with aHCC, including pts with a best overall response (BOR) of progressive disease (PD). Methods: Sor-exp pts received NIVO (3 mg/kg Q2W) in a phase 1/2 dose-expansion cohort regardless of PD-L1 status. Impact of antitumor activity on median OS (mOS) was determined by calculating change in target lesion size from baseline using quartile analyses (25% cutoff). Nonconventional benefit was analyzed by reductions or stabilizations in target lesion size after progression in pts with a BOR of PD. Results: Sor-exp pts (N=145) had a median follow-up of 14.9 mo. The ORR (RECIST v1.1) was...