Profiling exosomal mRNAs in patients undergoing immunotherapy for malignant melanoma.

e22159 Background: Traditionally, oncology biomarker discovery and development has required the use of material obtained from tissue biopsies. However, recent developments in the exosome field have allowed biomarker research in biofluids to evolve. Exosomes are highly stable microvesicles, approximately 30-200 nm in diameter, that are shed by cells into all biofluids, including blood, urine, and CSF, carrying a rich source of intact protein and RNA. RNA can be efficiently isolated and addressed using technologies such as RT-qPCR and NGS. Here we demonstrate the use of RNA extracted from these vesicles to monitor transcriptional changes in response to an immunotherapy treatment for malignant melanoma. Methods: Exosomes were isolated, using exoRNeasy columns, from plasma collected from malignant melanoma patients treated with Ipilimumab. Patients were split in two groups, based upon either a positive or negative response to the therapy (15 patients in total). Plasma was collected pre-treatment (baseline) an...