Molecular predictors of response to pembrolizumab in thymic carcinoma

Thymic carcinoma is rare and has a poorer prognosis than thymomas. The treatment options are limited after failure of platinum-based chemotherapy. We previously performed a single center phase II study of pembrolizumab in patients with advanced thymic carcinoma, showing a 22.5% response rate. Here, we characterized the genomic and transcriptomic profile of thymic carcinoma samples from 10 patients (5 non-responders vs 5 responders) in this cohort, with the main aim of identifying potential predictors of response to immunotherapy. We found that expression of PDL1 and alterations in genes or pathways that correlated with PD-L1 expression (CYLD and BAP1) could be potential predictors for response or resistance to immunotherapy in patients with advanced thymic carcinoma. Our study provides insights into potential predictive markers/pathways to select patients with thymic carcinoma for anti-PD-1 immunotherapy. In this paper, we characterized the genomic profile of 10 patient samples (5 responders vs 5 non-responders) using whole exome sequencing and whole transcriptome sequencing.