Combining immunotherapy with bacterial injection shows promise in treatment-refractory solid tumors
MD Anderson Research Highlight July 16, 2025
Solid tumors contain areas with low oxygen levels, known as hypoxic regions, that are associated with treatment resistance, aggressive growth and an increased risk of metastasis. In previous studies, injecting tumors with Clostridium novyi-NT, a non-toxic bacteria species that thrives in hypoxic environments, can trigger an antitumor response. A new Phase Ib trial led by , combined this approach with intravenous (IV) pembrolizumab immunotherapy treatment. Adding IV immunotherapy amplified the bacteria¡¯s ability to destroy cells, boosting the T cell-mediated immune response. Of 16 patients, four had partial responses, with one having a complete response. The median duration of response was 10.9 months, and stable disease was observed in 69% of the patients. While there was one grade three dose-limiting toxicity, all other adverse effects seen in more than 10% of patients were localized and manageable. These results highlight the therapeutic potential of this combination for patients with treatment-refractory solid tumors. Learn more in .
This is another important step on this promising path that could help a number of patients with hard-to-treat cancers that do not respond to current therapies..