Cancer: Probiotic may boost immunotherapy to treat renal cell cancer

Combining live biotherapeutic product CBM588 (a probiotic) with immunotherapy can enhance anti-tumour responses in patients with metastatic renal cell cancer, according to the results of a phase 1 clinical trial published in Nature Medicine. These findings underscore the potential of modulating the bacteria within the gut to augment immunotherapy in patients with cancer.

The collection of microorganisms in the gut (microbiota) are involved in regulating the immune system, with the specific composition of the microbiome known to modulate the efficacy of immunotherapy in patients with cancer. An imbalance between strains of bacteria in the gut is associated with diseases such as inflammatory bowel disease, and some specific bacteria relate to an increased risk of cancer through the production of carcinogenic toxins, or resistance to anti-tumour therapies.

Sumanta Pal, Sarah Highlander and colleagues conducted a phase 1 clinical trial in a cohort of 29 patients (mean age of 66 years, 72% male) with metastatic renal cell carcinoma. Patients were randomized to receive a standard combination of immune checkpoint inhibitors — a form of immunotherapy — with or without oral supplementation with a live biotherapeutic product (CBM588) that modulates the microbiome, including bifidobacteria, within the gut. Bifidobacterium species have been previously associated with improved response to immune checkpoint inhibitors. The authors found that patients who received CBM588 achieved improved and durable responses to immune checkpoint inhibitor treatment, with no differences in toxicity compared to the control group. Analysis of stool samples from these patients confirmed an increase in the number of bifidobacteria species in clinical responders and was associated with longer progression-free survival and immune activation.

The authors conclude that their data appear to support the potential of CBM588 to improve the outcomes of patients with cancer who are undergoing immunotherapy. The results will, however, need to be confirmed in larger studies and for additional tumour types.