Thevenet, Thomas

TPS660 Background: Deeper comprehension of gastroenteropancreatic neuroendocrine tumor (GEP-NET) characteristics has led to development of therapeutic interventions such as targeted radionuclide therapies (TRT). In the prospective, randomized, controlled, open-label, multi-center, Phase III COMPOSE trial, the radiolabeled somatostatin analogue 177Lu-edotreotide will be compared to approved standard of care with everolimus, CAPTEM or FOLFOX in patients with well-differentiated aggressive grade 2 and 3 (Ki-67 index 15−55%), somatostatin receptor positive GEP-NETS. While TRT is advantageous, a key unmet need is to identify additional markers intended to guide patient selection for TRT. This is highly relevant as TRT is a therapy of growing interest likely to be broadly available for patients with variable phenotypes. Profiling analysis as part of COMPOSE plans to analyze the genetic signature of GEP-NETS through full exome sequencing and gene expression analysis of tumor histology and longitudinal blood samples. This analysis may guide detection of pathogenic mutations in NET patients, to potentially inform treatment and surveillance strategies. Methods: Whole exome analysis of tumor-suppressor- and proto-oncogenes included in several pan-cancer panels, upstream and downstream regulators, and novel candidate genes, will be studied. Following patient consent, historical tumor biopsy and blood samples will undergo genetic analysis. Genetic profiling analysis inclusion will not impact trial involvement or disease management. DNA will be assessed to determine the impact of different types of mutations; mRNA will be assessed to confirm and quantify these assumptions and compare gene expression at different treatment phases. Samples will be analyzed in a central pathology laboratory. The aim of this analysis is to develop software that would integrate genetic data with structural and functional imaging, histopathology and phenotype information for implementation into clinical practice. Clinical trial information: NCT04919226 .