Modulation of the tumor promoting functions of cancer associated fibroblasts by phosphodiesterase type 5 inhibition increases the efficacy of chemotherapy in human preclinical models of esophageal adenocarcinoma

The chemotherapy resistance of esophageal adenocarcinomas (EAC) is underpinned by cancer cell extrinsic mechanisms of the tumor microenvironment (TME). We demonstrate that by targeting the tumor-promoting functions of the predominant TME cell type, cancer associated fibroblasts (CAF) with phosphodiesterase type 5 inhibitors (PDE5i) we can enhance the efficacy of standard-of-care chemotherapy. These findings demonstrate that CAF drive chemotherapy resistance in EAC and can be targeted by repurposing PDE5i, a safe and well tolerated class of drug administered to millions of patients world-wide to treat erectile dysfunction. Overall design: RNA sequencing was used to compare the transcriptomes of esophageal cancer specimens, and esophageal cancer specimen derived cells established and expanded on fibroblast feeder layer cells and subsequently grown in 3D-tumour growth assays with and without mesenchymal stem cells (as described in detailed in PMID:27736801).