Avelumab (MSB0010718C), an anti-PD-L1 antibody, in patients with previously treated, recurrent or refractory ovarian cancer: A phase Ib, open-label expansion trial.

5509 Background: The programmed death-1 receptor (PD-1) and its ligand (PD-L1) are key therapeutic targets in the reactivation of the immune response against multiple cancers. Avelumab (proposed INN) (MSB0010718C) is a fully human anti-PD-L1 IgG1 antibody currently being investigated in clinical trials. Here we present results from a cohort of patients (pts) with recurrent or refractory ovarian cancer in an ongoing phase Ib study (NCT01772004). Methods: Pts with ECOG PS 0-1 received avelumab at 10 mg/kg Q2W. Best overall response (BOR) and progression-free survival (PFS) were assessed according to RECIST 1.1. Adverse events (AEs) were evaluated by CTCAE v4.0. A prespecified analysis of 23 pts with follow-up of ≥ 2 months showed confirmed and unconfirmed partial responses (PRs), leading to cohort expansion to 75 pts. Results: Seventy-five pts were enrolled from November 2013 to November 2014 (median age 62 [range 38-84]; ECOG PS 0 [41%] or 1 [59%]; median of four prior lines of therapy). As of January 2015, median duration of treatment with avelumab was 10 weeks (range 2-54 weeks), and 27 pts remained on treatment. Efficacy data from the 23 pts followed-up for ≥ 2 months (range 2–8 months) demonstrated 4 pts (17.4%, [95% CI, 5.0%, 38.8%]) achieved an unconfirmed BOR of PR,11 (47.8%) had stable disease, and 2 pts had >30% tumor shrinkage after progression was reported. Median PFS was 11.9 weeks (95% CI, 5.9, not reached), and the PFS rate at 24 weeks was 33.3% (95% CI, 11.5, 57.2). Drug-related treatment-emergent AEs (TEAEs; all grades) were reported in 18 pts (78.3%), and 2 pts (8.7%) experienced grade ≥ 3 drug-related TEAEs (increased lipase [1] and elevated creatine kinase and autoimmune myositis that led to discontinuation [1]). No drug-related serious TEAEs occurred. The most commonly reported drug-related TEAEs (> 10%) were fatigue, nausea, and diarrhea. Conclusions: These data represent the largest reported dataset of pts with recurrent ovarian cancer treated with anti-PD-L1 therapy. Avelumab demonstrated an acceptable safety profile and is clinically active in this heavily pretreated ovarian cancer pt population. Clinical trial information: NCT01772004.