A potentially dangerous bacteria for humans could help fight cancer. Called Clostridium novyi-NT, it is able to target malignant cells to encourage the body’s immune response against cancer.
A potentially fatal bacterium for humans capable of killing cancer cells. This is the subject of a Phase 1 clinical trial conducted by researchers at the MD Anderson Cancer Center at the University of Texas, Houston. Presented at the of the Fourth International Conference SHOUT. CIMT-EATI-AACR on cancer immunotherapy currently underway in New York, the results of the clinical trial are promising.
The researchers found that when injected into a cancerous tumor, the bacterium Clostridium novyi-NT was able to directly attack malignant cells and stimulate the body’s immune defenses against them.
Stimulate the body’s immune response
Until now, however, the bacterium Clostridium novyi-NT was considered above all as dangerous. Suspected of causing gas gangrene and sepsis if the infection spreads to the wound, the bacteria notably caused the death of several drug addicts in 2000.
In this clinical trial, however, the Clostridium novyi-NT strain was weakened to prevent it from producing its toxin. Now considered “non-toxic”, the bacterium was injected between November 2013 and April 2017 in 24 patients with solid tumors refractory to treatment: 15 of them had sarcoma, 7 presented with various carcinomas and 2 patients had melanoma . Tumors were targeted with a single dose of Clostridium novyi-NT ranging from 10,000 to 3 million spores. Contaminated with the bacterial infection for a week, the patients were then given antibiotics to kill the bacteria, the researchers said.
Although limited to a few patients, the results of the trial are promising. Lead author Prof. Filip Janku said bacteria germinated in cancer cells in 11 of 24 patients, leading to tumor cell death. In addition, tumor shrinkage greater than 10% was observed in 23% of patients. However, says Professor Janku, this may be an underestimate since the infection causes inflammation of the surrounding tissue, making the lesion larger than it actually is.
After this bacterial treatment, the cancer stabilized in 21 patients. When both injected and non-injected lesions were included, the stable disease rate was 86%, the researchers reported.
Destruction of the tumor
For researchers, this is great news. “Despite the absence of clinical signs of germination in some patients, we observed an improvement in the immune responses specific to the tumor by the increase in the secretion of T cytokines and the increase in the presence of lymphocytes infiltrating the tumors”, Janku noted. “From these preliminary results, it appears that Clostridium novyi-NT is able to activate the immune response in addition to causing tumor destruction.”
“This is where the promise of this type of therapy lies. You would expect the injected lesion to have some type of response because you are disrupting the tumor cells. What would be interesting is that this would be so. can trigger an immune response that could eventually support uninjected tumors. This is the holy grail of immunotherapy, “said Sacha Gnjatic, deputy director of the Human Immune Monitoring Center at Mount Sinai, New York.
Now, researchers have moved on to the next phase, in which patients taking the immunotherapy drug pembrolizumab (Keytruda) will also be treated with a single injection of Clostridium novyi-NT. According to them, these two treatments used in combination will create a strong immune response against cancer.
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