Updated outcomes and exploratory analysis of RENMIN-215: tislelizumab plus fruquintinib and fecal microbiota transplantation in refractory microsatellite stable metastatic colorectal cancer.

Primary analysis of the open-label, single-arm, phase II RENMIN-215 trial (primary data cutoff date: July 10, 2023) showed promising efficacy and tolerable safety with tislelizumab plus fruquintinib and fecal microbiota transplantation (FMT) in patients with refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC). Here, we reported updated survival and safety results with a median follow-up of 34.0 months (data cut-off May 20, 2024), as well as patient-reported outcomes and laboratory analysis. Twenty patients with MSS mCRC resistant or refractory to at least second-line therapy were enrolled and received tislelizumab plus fruquintinib and FMT. The primary endpoint was progression-free survival. Secondary endpoints included overall survival (OS), objective response rate (ORR), disease control rate, safety, health-related quality of life questionnaire and exploratory laboratory tests. In addition, 94 mCRC patients who received third-line or above immunotherapy in real world were screened for propensity score matching (PSM) analysis to compare efficacy. Our results showed that the median OS was 13.7 months (95% CI, 9.3-17.7), and the ORR was 20.0% (95% CI, 5.7-43.7). After PSM, the median OS benefit of the study regimen remained statistically significant (HR = 0.26; 95% CI, 0.07-0.95; = 0.042). Patients with primary tumor surgery had better clinical outcomes. No new safety concerns were detected. Seven (35.0%) patients had one or more grade 3 treatment-related adverse events. The majority of patients had improved or stable global health status (GHS). Median time to deterioration for GHS was 7.7 months. Peripheral blood lymphocyte analysis showed that increased gamma-delta 2 T cells were positively associated with improved response and survival. To conclude, the updated results provide further evidence of sustained antitumor activity of tislelizumab plus fruquintinib and FMT in heavily pretreated MSS mCRC patients with a consistent safety profile.