COLOSOTO Trial Explores Chemotherapy-Sparing KRAS G12C Strategy in Frail Metastatic Colorectal Cancer : Digestive and Liver Disease | May 2026
Introduction
KRAS G12C mutations represent a clinically important molecular subtype of metastatic colorectal cancer (mCRC), occurring in approximately 3–4% of cases and often associated with aggressive disease biology and limited responsiveness to conventional therapies. Recent advances in KRAS G12C inhibitors combined with EGFR blockade have demonstrated promising activity in refractory disease, opening new possibilities for biomarker-driven treatment strategies in colorectal cancer.
Problem Statement
Frail and elderly patients with unresectable mCRC frequently cannot tolerate standard doublet or triplet chemotherapy regimens because of age, comorbidities or impaired performance status. Current low-intensity fluoropyrimidine-based approaches offer only modest efficacy, and many vulnerable patients never reach later-line targeted therapies. Whether KRAS G12C-targeted combinations can be safely and effectively integrated earlier in treatment using chemotherapy-sparing strategies remains unknown.
Summary
The COLOSOTO trial is the first prospective study evaluating first-line treatment with 5-fluorouracil, panitumumab and sotorasib in frail or elderly patients with unresectable KRAS G12C-mutated metastatic colorectal cancer who are unfit for intensive chemotherapy. Building on encouraging activity observed with KRAS G12C inhibition plus EGFR blockade in refractory settings, this study investigates whether earlier deployment of this biologically driven combination can improve outcomes while maintaining tolerability in a clinically vulnerable population. The trial specifically targets patients traditionally underserved by standard treatment paradigms, including older adults and patients with impaired performance status. By combining limited-intensity chemotherapy with dual molecular targeting, the strategy aims to balance efficacy and toxicity while potentially avoiding the complications associated with aggressive cytotoxic regimens. The study also incorporates comprehensive geriatric assessment, quality-of-life evaluation and translational biomarker analyses including circulating tumor DNA monitoring, emphasizing a modern personalized oncology approach. Although limited by its single-arm design and relatively small sample size, the trial addresses a major unmet need in gastrointestinal oncology and may establish a new first-line therapeutic paradigm for frail patients with KRAS G12C-mutated colorectal cancer.
