Single-center phase 2 trial of fecal microbiota transplantation plus tislelizumab and fruquintinib for microsatellite stable metastatic colorectal cancer

Microsatellite stable metastatic colorectal cancer (MSS mCRC) shows a low response to PD-1 inhibitors. Antiangiogenic can enhance anti-PD-1 efficacy, and increasing evidence supports a close relationship between gut microbiome and anti-PD-1 efficacy. The phase 2 RENMIN-215 trial (at Renmin Hospital of Wuhan University, China) evaluated the combination of fecal microbiota transplantation (FMT) with tislelizumab (anti-PD-1) and fruquintinib (anti-VEGFR) as third- or higher-line option for MSS mCRC. The combination was active with median progression-free survival (primary end point) of 9.6 months, median overall survival of 13.7 months, objective response rate 20%, disease control rate 95%, clinical benefit rate 60%, and median duration of response 8.1 months. Grade 3 or 4 TRAEs were seen in 30% of patients; there were no grade 5 TRAEs. The authors conclude that FMT plus tislelizumab and fruquintinib may be a valuable new third-line treatment option for MSS mCRC.