According to a new study, a ‘poop transplant’ can likely help patients with advanced melanoma respond to immunotherapy.
Melanoma is a rare, but extremely dangerous type of skin cancer. Although the exact mechanism behind the disease is unclear, common factors include sun exposure, fair skin, and family history of melanoma. Treatment typically involves excision through surgery. Or chemotherapy and immunotherapy if cancer has metastasized. However, only 30-40% of patients with advanced melanoma respond to immunotherapy. Thus, lowering their survival rate.
[Immunotherapy] works by essentially unleashing the body’s own immune cells against cancer. The problem is that these drugs don’t work perfectly, in that they don’t work all the time.
Dr. Diwakar Davar, co-author of the study
Now, a study published in the journal Science suggests that a fecal transplant could help patients with advanced melanoma respond to immunotherapy. The study was conducted by researchers at the National Cancer Institute (NCI) and the University of Pittsburg.
The clinical trial enrolled 15 patients with advanced melanoma who had previously not responded to either pembrolizumab or nivolumab. Both of which are immune checkpoint inhibitors, a form of immunotherapy, that allows the immune system to attack cancer cells.
The fecal samples for the transplant were taken from seven melanoma patients who had previously responded to the drug. However, before transferring them into the study participants’ colons, researchers analyzed the samples for infectious agents. The stool was further treated with saline and other solutions, before transplant. After the fecal transplant, all 15 participants also received doses of Pembrolizumab every three weeks. Researchers tracked their progress for an average of 12 months.
Fecal Transplant ‘Reprograms’ Microenvironment of Tumors
As the name implies, the procedure involves transferring stool, containing microbes, from healthy individuals into another. This alters the gut microbiome, which plays an important role in the functioning of the immune system. Other than recurring clostridium difficile infections, the procedure has also gained support for treating various other diseases. Such as inflammatory bowel disease, Parkinson’s, and even auto-brewery syndrome.
Moreover, a previous research had shown tumor-bearing mice responding to immunotherapy after scientists altered their gut bacteria. Therefore, Dr. Diwakar Davar and his team tested whether fecal transplants could help patients with advanced melanoma resistant to immunotherapy drugs.
Out of the 15 patients, 6 began to respond to treatment. Three of which showed a large to complete eradication of their cancer. While the other half’s cancers stopped growing. Moreover, the median survival rate for the 6 patients increased to 14 months. Upon investigating the gut of the patients, the researchers saw increased amounts of bacteria that generally activate immune cells.
Additionally, they also noticed a reduction in the number or proteins that are responsible for suppressing the immune response to cancer cells. Therefore, the results of the study suggest that altering the gut bacteria through fecal transplants may help enhance patients’ response to immunotherapy drugs.
However, the study has a few limitations. Along with the small sample size, it is unclear as to why the rest of the participants did not benefit from the fecal transplant.
Reference:
Davar, Diwakar, et al. “Fecal Microbiota Transplant Overcomes Resistance to Anti–Pd-1 Therapy in Melanoma Patients.” Science, vol. 371, no. 6529, 2021, pp. 595–602., doi:10.1126/science.abf3363.
