Bacterial Supplement May Improve CPI Outcomes in Metastatic Kidney Cancer

Results from a small study suggest that a live bacterial supplement might improve outcomes in patients receiving checkpoint inhibitor (CPI) immunotherapy for advanced kidney cancer, possibly by increasing the abundance of certain beneficial bacteria.

Data from an open-label phase 1 trial demonstrate that use of a live strain of Clostridium butyricum (CBM588) orally in combination with the CPIs nivolumab/ipilimumab significantly improved progression-free survival (PFS) in patients with metastatic renal cell carcinoma (mRCC) compared with nivolumab/ipilimumab alone, investigators reported in Nature Medicine.

“To our knowledge, this is the first randomized clinical trial to demonstrate that a live bacterial product can modulate the gastrointestinal microbiome and enhance immunotherapy response in cancer patients,” the study’s senior author Sumanta K. Pal, MD, a professor in the Department of Medical Oncology & Therapeutics Research at City of Hope in Duarte, California, said in a press release. “These results can help improve treatment options for patients with kidney cancer and is an important foundational step to bring about more effective targeted therapies for cancer treatment.”

The study included 30 treatment-naive patients with mRCC who had clear cell and/or sarcomatoid histology and intermediate- or poor-risk disease. Investigators randomly assigned patients 2:1 to receive nivolumab/ipilimumab with or without daily oral CBM588, respectively. PFS was significantly longer in patients among the CBM588 recipients compared with those not receiving the bacterial supplement (12.7 vs 2.5 months). CBM588 was significantly associated with an 85% decreased risk for progression.

Dr Pal’s team tested whether use of CBM588 could improve CPI response by increasing the relative abundance of Bifidobacterium species in the gut. Previous studies have shown that Bifidobacterium species are associated with enhanced clinical benefit from CPIs. The investigators found no significant difference in the abundance of Bifidobacterium species between treatment arms overall, but did note significant increases in patients who responded to CBM588 plus nivolumab/ipilimumab. The groups did not differ significantly with respect to treatment-related toxicity.

Want to read more?