New Pill Shows Promise for Hard-to-Treat Melanoma Patients

Patients with advanced melanoma who ran out of treatment options just got a lifeline from an unlikely source: their gut bacteria.

Cambridge biotech company Microbiotica announced that its experimental pill, MB097, met all safety goals in a 41-patient trial across the UK, France, Italy, and Spain. The once-daily capsule contains nine strains of beneficial bacteria designed to wake up the immune system's cancer-fighting abilities.

The trial focused on patients whose melanoma no longer responded to standard immunotherapy drugs. These patients face limited choices once their first treatment stops working. MB097 aims to change that by resetting the gut microbiome to help existing cancer drugs work again.

All 41 participants took MB097 alongside pembrolizumab, a proven anti-cancer drug. Half the group also received an antibiotic beforehand to help the beneficial bacteria take hold in their digestive system. The combination proved safe and well-tolerated, with early hints of effectiveness that researchers found encouraging.

Dr. Pippa Corrie from Cambridge University Hospitals, who coordinated the study, called the approach "an easy and reproducible way of modifying the microbiome" compared to messier treatments like fecal transplants. Patients simply swallow a capsule each day.

The science builds on growing evidence that gut bacteria influence how well cancer immunotherapies work. Some bacteria help immune cells recognize and attack tumors, while others seem to dampen that response. MB097 delivers the helpful strains directly.

The Ripple Effect

This marks Microbiotica's second successful trial this year, following positive results for an ulcerative colitis treatment in early 2026. The back-to-back wins validate the company's approach of using precision bacterial mixtures as medicines, not just supplements.

Patients who benefited during the initial six months entered an extension study. They can continue receiving pembrolizumab for up to 18 more months while researchers track their progress. Those results will help determine whether MB097 moves to larger trials in broader melanoma patient groups.

CEO Tim Sharpington called the results "further validation of our clinic-first discovery platform." The company identified which bacterial strains to include by studying gut samples from cancer patients who responded well to immunotherapy, then recreating that winning combination in pill form.

The trial's success offers tangible hope for metastatic melanoma patients with primary resistance to immunotherapy, a group with significant unmet medical needs and dwindling treatment paths.

One daily pill could soon mean the difference between giving up and fighting on.