In Kobe, Japan, a scientist has developed a cancer treatment that comes in the form of a probiotic yogurt drink. Dr. Toshiro Shirakawa, a cancer researcher at Kobe University, has created an oral vaccine called B440 that uses genetically engineered gut bacteria to help the body fight cancer. The bacteria he chose, called Bifidobacterium longum, is the same type found in many probiotic products already sold in stores. His team's work was published in the journal JCO Oncology Advances.
Cancer treatments have come a long way in recent years. One powerful approach uses drugs called immune checkpoint inhibitors, which essentially take the brakes off the immune system so it can attack cancer cells. But these drugs don't work for everyone, and cancers can sometimes find other ways to escape treatment. When that happens, patients often run out of good options.
"When patients no longer respond to immune checkpoint inhibitors, effective treatment options are often limited," Shirakawa said. "We need new approaches that can safely enhance anti-tumor immunity."
His solution was to engineer friendly gut bacteria to carry pieces of a cancer protein called WT1 directly to the immune system in the gut. The idea is that these bacteria, when swallowed, could teach the body to recognize and attack cancer cells more effectively.
Shirakawa's team tested the vaccine in a small clinical trial with 12 patients who had advanced urinary tract cancer that had spread through their bodies and no longer responded to standard treatments. The results were encouraging. Most side effects were mild, with only three patients experiencing a temporary increase in a normal inflammatory molecule in their blood. Of the twelve patients, six showed strong immune responses against the WT1 protein after receiving B440. Those six patients also stayed cancer-free longer than the others.
The remaining six patients did not show new immune responses, suggesting B440 might work better as a booster for patients who already have a small immune foothold against their cancer. This finding could help doctors figure out which patients might benefit most from this treatment.
After the trial, seven patients went on to receive another round of immune checkpoint inhibitor therapy. Three of them saw their tumors shrink, and all three had shown immune responses after taking B440.
This was an early, exploratory study, so more research is needed. But Shirakawa's team sees potential in using engineered gut bacteria as a new way to complement existing cancer treatments and help patients who have run out of options.