Serum soluble MAdCAM-1: A new biomarker for cancer immunotherapy.

4548 Background: Antibiotics (ATB) deviate the gut taxonomic microbiota composition and have a deleterious impact on survival in ICI-treated pts. ATB downregulate the ileal mucosal addressin cell adhesion molecule-1 (MAdCAM-1), leading to the recirculation of immunosuppressive enterotropic T cells into the tumor and ICI resistance. Here, we aimed to assess the prognostic impact of MAdCAM-1 in ICI-treated mRCC pts. Methods: The GETUG-AFU 26 NIVOREN phase II trial (NCT 0301335) is a multicentric study that assessed the activity and safety of Nivolumab in pts with clear cell mRCC after anti-angiogenic therapy. We measured serum soluble MAdCAM-1 (sMAdCAM-1) levels (correlating ileal MAdCAM-1 transcripts) using Human Luminex Discovery Assay in the available plasma. Progression-free survival (PFS), overall survival (OS) and clinical benefit rate (CBR) were assessed using sMAdCAM-1 median as a cut off value (high if >median and low if 更多