Plasma arginine as a predictive biomarker for outcomes with immune checkpoint inhibition in metastatic colorectal cancer: a correlative analysis of the CCTG CO.26 trial.

Background: Nutritional stress is a mechanism that allows tumor cells to evade the immune system. Arginine (ARG), an amino acid involved in immunomodulation, aids in regulating T-lymphocyte cell activity and the antitumor response. ARG deficiency in the tumor microenvironment can impair T-cell response while ARG supplementation may promote antitumor immune activity.

Effect of Combined Immune Checkpoint Inhibition vs Best Supportive Care Alone in Patients With Advanced Colorectal Cancer: The Canadian Cancer Trials Group CO.26 Study.

Importance: Single-agent immune checkpoint inhibition has not shown activities in advanced refractory colorectal cancer (CRC), other than in those patients who are microsatellite-instability high (MSI-H).

Objective: To evaluate whether combining programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibition improved patient survival in metastatic refractory CRC.

Design, Setting, And Participants: A randomized phase 2 study was conducted in 27 cancer centers across Canada between August 2016 and June 2017, and data were analyzed on October 18, 2018.