B Cells: a New Immunotherapy Target for Melanoma

Researchers have found evidence that B cells might play an important role in immunotherapy for melanoma. Immunotherapy is a form of cancer treatment that uses the body’s own immune system to recognize and fight the disease. It comes in a variety of forms, including cancer vaccines, targeted antibodies, and tumor-infecting viruses. Only some cancer patients currently benefit from this kind of therapy.

In the case of melanoma, which is a particularly aggressive form of skin cancer, established immunotherapies focus on T cells. T cells play an important role in controlling and shaping the immune system, and they are able to directly kill cancer cells while also recruiting other cells into the process.

But a study published today in Nature Communications shows that, alongside T cells, B cells, which produce antibodies and messenger molecules, play a critical role in triggering melanoma-associated inflammation. The researchers found that, in the case of melanoma, B cells direct T cells to the tumor via the secretion of distinct messenger molecules.

“Immunotherapy has transformed cancer treatment. It unleashes T cells so they can fight cancer in a more effective way,” explains first author Johannes Griss of the Medical University of Vienna and EMBL-EBI. “For the first time, we found that B cells also play an important part in the process and help T cells find the tumor. The role of B cells in immunotherapy is still largely unknown, but it seems they may have more impact than previously thought.”

During the study, the researchers observed that when B cells were depleted from melanoma patients, the number of T cells and other immune cells dramatically decreased within the tumors as well. In subsequent experiments, the researchers showed that a special subtype of B cells seems to be responsible for guiding T cells and other immune cells to the tumor. The same subtype also increased the activating effect of current immune therapies on T cells.

Interestingly, melanoma cells seem to force B cells to develop into this distinct B cell subtype. “Further research is required to answer questions such as how melanoma cells modify B cells, what mechanism B cells use to support the activation of T cells, and how we can help these B cells to support current immunotherapies in cancer patients,” Griss says.

Image: Using multiplex-immunostaining to characterize B cells. Image courtesy of Christine Wagner.