Gut microbiota and the colorectal cancer tumor microenvironment: From carcinogenic mechanisms to therapeutic opportunities

Table 1 Current clinical trials of combining gut microbiota modulation and immunotherapy in colorectal cancer

Title	Intervention	Patient population	Phase	Trial ID
FMT and re-introduction of anti-PD-1 therapy (pembrolizumab or nivolumab) for the treatment of metastatic CRC	Colonoscopic FMT-IV pembrolizumab + oral FMT capsules	dMMR/MSI-H metastatic CRC; anti-PD-1 nonresponders	II	NCT04729322
FMT capsule + anti-PD-1 for PD-(L)1 resistant digestive system cancers	FMT capsules (1st week: 3 consecutive days; then maintenance dose) + anti-PD-1 therapy (every 2 weeks, up to 6 cycles)	Gastrointestinal cancer	I	NCT04130763
A phase Ib trial to evaluate the safety and efficacy of FMT and nivolumab in subjects with MSI-H, dMMR CRC	FMT capsules + nivolumab	MSI-H, dMMR CRC	Ib	NCT04521075
Pembrolizumab with intratumoral injection of Clostridium novyi-NT	Pembrolizumab + Clostridium novyi-NT + lifelong oral doxycycline	Advanced solid tumors (including CRC)	Ib	NCT03435952
FMT plus tislelizumab and fruquintinib in refractory MSS metastatic colorectal cancer	FMT + tislelizumab + fruquintinib	Refractory MSS mCRC	II	RENMIN-215

FMT: Fecal microbiota transplantation; CRC: Colorectal cancer; dMMR: Deficient DNA mismatch repair; MSI-H: Microsatellite instability-high; MSS: Microsatellite stable; mCRC: Metastatic colorectal cancer; NT: Nontoxic.