A Phase II Trial of Pembrolizumab and Vorinostat in Recurrent Metastatic Head and Neck Squamous Cell Carcinomas and Salivary Gland Cancer

Purpose: This clinical trial combined pembrolizumab and vorinostat in recurrent/metastatic squamous cell carcinomas of the head and neck (HN), and salivary gland cancer (SGC). Patients and Methods: Patients with progressing incurable HN and SGC, Eastern Cooperative Oncology Group (ECOG) <= 1, no prior immunotherapy, RECIST1.1 measurable disease, and normal organ function were eligible. Pembrolizumab 200 mg was given intravenous every 21 days, and vorinostat 400 mg given orally 5 days on and 2 days off during each 21-day cycle. Primary endpoints were safety and objective response rates. Results: FromNovember 2015 to August 2017, 25 patients with HN and 25 SGC were enrolled. Median age was 61 (range, 33-86) years, 39 (78%) were male, 21 (62%) were never smokers, and 27 (54%) had ECOG 0. In HN, 13 (52%) were p16+ oropharynx. Most common SGC histologies were adenoid cystic 12 (48%), acinic cell 3 (12%), and mucoepidermoid 3 (12%). Adverse events (AEs) in all patients were: 27 (54%) with grade >= 1 and 18 (36%) with grade >= 3. The most common AEs in all patients were renal insufficiency in seven, (14%), fatigue in six, (12%), and nausea in three (6%). There were three (12%) deaths on study. Responses in HN were complete response (CR) 0, partial response (PR) eight (32%), and stable disease (SD) five (20%). Efficacy in SGCs was CR 0, PR four (16%) in one lymphoepithelioma-like carcinoma, two acinic cell, one adenoid cystic, and SD 14 (56%). In the HN group, median follow-up (mFUP) was 12.6 months, median overall survival (mOS) was 12.6 months, and median progression-free survival (mPFS) was 4.5 months. In SGC, mFUP was 13.1 months, mOS was 14.0 months, and mPFS was 6.9 months. Conclusions: This combination demonstrated activity in HN, with fewer responses in SGC. Toxicities were higher than reported with pembrolizumab alone.