Efficacy of fecal microbiota transplantation in patients with anti-PD-1–resistant/refractory gastrointestinal cancers.
Zhi Peng, Xiaotian Zhang, Tong Xie, Siyuan Cheng, Zihan Han, Shulin Wang, Zongwen Ban, Xiaomin Xu, Zhengnong Zhu, Jing Zhu, Xiaochen Yin, Sumin Li, Lin Shen
Abstract
389 Background: Gut microbiome that changed the response to anti-PD-1 therapy (aPD-1) against melanoma by fecal microbiota transplantation (FMT) has been reported. To investigate whether resistance to aPD-1 against gastrointestinal (GI) cancers can be overcome by FMT, this single arm, open label, investigator-initiated trial explored the efficacy of combination of FMT + nivolumab in patients with aPD-1 resistant/refractory (aPD-1r)-GI cancers. Methods: Ten patients were planned to be enrolled. Interim analysis was planned when at least one patient demonstrated effective outcome. FMT capsules were from healthy donors. FMT capsules (CFU≥1×10 12 ) were administered in the first week. Nivolumab (3mg/kg, q2w) combined with a maintenance dose of FMT capsules (CFU≥1.5×10 11 ) were started at Week 2 and continued for 6 cycles or until progress of disease (PD) after 3 cycles of treatment. If patient responded to the treatment and would be benefit from the treatment beyond 6 cycles, patients would enter the Expended Excess Program to continue the therapy. RECIST v1.1 evaluation was performed every 3 cycles. Stool samples were collected every 2 weeks for metagenomic analysis of gut microbiota. Results: 8 aPD-1r patients were enrolled and finished the study by the time of this analysis. Nivolumab + FMT therapy was well tolerated. No serious adverse reaction was observed. 8 patients completed 3 cycles of treatment. Metagenomic analysis of gut microbiota from Responders (R) and Non-Responders (NR) groups revealed the gut microbial composition of R group is significantly closer to that of the donor than NR group, which indicated much better colonization of donor microbiota in R. Alpha diversity was significantly higher in R than that in NR, along with a set of differential bacterial species and biological process functions including dTMP biosynthetic process enriched, suggesting gut microbiome’s potential role in the treatment. The flow cytometry analysis indicated a significant increase of IFN-ϒ+ cells in PBMCs in R at Day 8 after FMT (the highest increase during the study), before combination therapy had started. A significant increase in Ki-67+ cells in PBMCs was also observed in the R group. Relative abundance of differential bacterial species enriched in R were found to be significantly negative correlated with tumor markers like CA199 and tumor volume, and some were positively correlated with expression of CD3+CD4+ cells and CD3+CD8+ cells. Conclusions: FMT+aPD-1 may overcome the resistance to aPD-1 against GI cancer via changing gut microbiota structure. Trial registration number: NCT04130763. Keywords: gastrointestinal cancers; fecal microbiota transplantation; anti-PD-1 therapy. Clinical trial information: NCT04130763 .