Patient-Level Omics Data Analysis Identifies Gene-Specific Survival Associations for a PD-1/PD-L1 Network in Pleural Mesothelioma

Immune checkpoint blockade targeting PDCD1 (PD-1) or CD274 (PD-L1) has demonstrated efficacy and interest across multiple cancers. However, the exact determinants of the response and cancer-specific molecular features remain unclear. A recent pan-cancer study identified a PDCD1/CD274-related immunotherapy network of 40 genes that had differential patient survival associations across multiple cancers. However, the survival relevance of this network in mesothelioma could not be assessed due to a lack of available survival data for the mesothelioma study included. Mesothelioma, a rare cancer that most commonly arises in the pleural membranes around the lung, does have immune checkpoint blockade as an approved treatment strategy, yet questions over its efficacy remain. RNA-seq data from 87 pleural mesothelioma patients were interrogated on cBioPortal to assess the role of the PDCD1/CD274 network identified in a previous study, in addition to identifying repurposed drugs that may have therapeutic efficacy. Extensive literature searches were conducted to identify known information from the literature around the genes shown to impact patient survival (CCR5, GATD3A/GATD3, CXCR6, GZMA, and TBC1D10C). The same literature validation was performed for putative repurposed drugs that were identified as potential immunotherapeutic adjuvants in the context of mesothelioma (disulfiram, terfenadine, maraviroc, clioquinol, chloroxine, and oxyphenbutazone). Only disulfiram returned a specifically focused research article based on the literature search. This article demonstrated cytotoxicity in a panel of five human MPM cell lines of mixed histology (epithelioid, biphasic, and sarcomatoid). There was little information on the remaining five drugs, yet the clear preclinical efficacy of disulfiram validates the methodology used herein and prompts further exploration of the remaining drugs in mesothelioma. This study ultimately sheds light on novel preclinical information of genes related to PDCD1/CD274 in mesothelioma, as well as identifying putative drugs that may have therapeutic efficacy either independently or as an immunotherapeutic adjuvant