A large cohort study of 18,932 patients with metastatic colorectal cancer (mCRC) has highlighted key factors affecting the receipt and survival outcomes of immune checkpoint inhibitors (ICIs) in routine clinical practice. Published today, the study found that patients with microsatellite instable (MSI-H) mCRC who received ICI-based therapy early in treatment had a 63% higher probability of survival compared to those treated with chemotherapy.
The research also revealed that in patients with microsatellite stable (MSS) tumours, certain factors like high albumin levels and prior antibiotic use were linked to improved survival when treated with ICIs. Specifically, those with high albumin levels had a 72% higher survival probability, while antibiotic use increased survival chances by 57%.
One of the key findings was the significantly higher likelihood of MSI-H patients receiving ICIs compared to those with MSS tumours. Additionally, patients with synchronous mCRC were less likely to receive ICIs than those diagnosed with metachronous mCRC. Among MSS patients, ICI therapy was associated with longer survival in those with high albumin or antibiotic use, though survival was notably shorter for those with synchronous mCRC.
The study underscores that while ICIs have proven effective for MSI-H mCRC, clinical characteristics such as albumin levels and antibiotic use in MSS cases can influence outcomes. These findings may help refine treatment strategies, particularly for MSS patients who typically show limited response to immunotherapy.
Reference
Bari S et al. Practice patterns and survival outcomes of immunotherapy for metastatic colorectal cancer. JAMA Netw Open. 2025;8(3):e251186.
