NRG-GI004/SWOG-S1610: Colorectal cancer metastatic dMMR immuno-therapy (COMMIT) study—A randomized phase III study of atezolizumab (atezo) monotherapy versus mFOLFOX6/bevacizumab/atezo in the first-line treatment of patients (pts) with deficient DNA mismatch repair (dMMR) or microsatellite instability high (MSI-H) metastatic colorectal cancer (mCRC).

Abstract

TPS232 Background: Despite the superiority in progression-free survival (PFS) of inhibition of programmed cell death-1 (PD-1) pathway in dMMR/MSI-H as compared to chemotherapy with either anti-vascular endothelial growth factor receptor (VEGFr) or anti-epithelial growth factor receptor (EGFr) antibodies in mCRC, more pts had progressive disease as the best response in the anti-PD1 monotherapy arm (29.4% vs. 12.3%) with mean PFS of 13.7 months ( N Engl J Med 2020; 383:2207). We hypothesize that the dMMR/MSI-H mCRC pts may be more effectively treated by the combination of PD-1 pathway blockade and mFOLFOX6/bevacizumab (bev) rather than with anti-PD-1 therapy (atezo) alone. Preclinical work demonstrated synergistic effects between anti-PD-1/anti-VEGF and between oxaliplatin/anti-PD-1 in murine CRC models and phase II data showed activity of anti-PD-1/anti-VEGF in chemotherapy refractory colon cancer. Additionally, in other solid tumor malignancies, anti-PD1 plus anti-VEGFr (i.e., HCC and RCC) as well as anti-PD1 plus chemotherapy (i.e., gastric and esophageal cancers) combinations are standard first-line treatments. Methods: The redesigned COMMIT study was reactivated on 1/29/2021 as a two-arm prospective phase III open-label trial randomizing (1:1) mCRC dMMR/MSI-H (211 pts) to atezo monotherapy versus mFOLFOX6/bev+atezo combination. Assuming our control arm, atezo monotherapy, 48% PFS at 24 months, as assessed by site investigator, we have 80% power to detect a hazard ratio of 0.6 (equivalent to 64.4% PFS at 24 months) with alpha 0.025 one-sided. Stratification factors include BRAFV600E status, metastatic site, and prior adjuvant CRC therapy. Secondary endpoints include OS, objective response rate, safety profile, disease control rate, duration of response, and centrally-reviewed PFS. Health-related quality of life is an exploratory objective. Archived tumor tissue and blood samples will be collected for correlative studies. Key inclusion criteria are: mCRC without prior chemotherapy for advanced disease; dMMR tumor determined by local CLIA-certified IHC assay (MLH1/MSH2/MSH6/PMS2) or MSI-H by local CLIA-certified PCR or NGS panel; and measurable disease per RECIST. Enrollment actively continues to the target accrual of 211 patients randomized between the two immunotherapy arms. Support: U10CA180868, -180822, -180888, UG1CA189867, U24CA196067; Genentech, Inc. Clinical trial information: NCT02997228.