While melanoma is less common than other skin cancers, it causes the majority of deaths from skin cancer. Immunotherapy has already had major impacts on patients with melanoma, and new findings could lead to even more.
B Cell Absence Drives Immune Suppression
According to new research published in The Journal of Immunology, B cells curbed melanoma progression by maintaining an immune-supportive tumor environment, while their absence drove immune suppression and tumor growth through antibody-independent, cell-mediated mechanisms in a mouse model.
The researchers observed that depletion of B cells in mice, either genetically or with anti-CD20 antibodies, accelerated melanoma growth, confirming that B cells were critical components of antitumor immunity.
“Our work raises the possibility that B cells could be harnessed for cancer immunotherapy. By identifying subsets of B cells with antitumor activity, there is potential to isolate and expand these cells for use as immunotherapy,” said Selin Oncul, PhD, Postdoctoral Fellow at University of Texas MD Anderson Cancer Center, and lead author of the study.
B Cells Regulate Antitumor Immunity
The anti-melanoma effect of B cells did not depend on plasma cells or antibody production, indicating that B cells primarily impacted melanoma growth through antigen presentation and interactions with other immune cells rather than antibodies. Depletion of B cells largely spared regulatory IL-10-producing B cells (Bregs), leading to a relative increase in this immunosuppressive population within the tumor microenvironment. The researchers say this is consistent with clinical data that demonstrate that melanoma patients with high expression of B cell markers such as CD19 and CD20 have better overall survival and improved responses to immune checkpoint therapy.
“Rather than acting solely as passive bystanders, B cells should be viewed as context-dependent regulators of antitumor immunity, capable of shaping T cell function and influencing the tumor microenvironment. Our results suggest the need for caution when considering B cell-depleting strategies in cancer patients,” shared Vahid Afshar-Kharghan, MD, Professor of Medicine The at University of Texas MD Anderson Cancer Center, and senior author of the study.
The researchers plan to build on this work by defining the specific B cell subsets that mediate tumor control in melanoma and clarifying how these cells regulate T cell function within the tumor microenvironment. From a clinical perspective, they will examine how B cells influence responses to immune checkpoint blockade, including PD-1 and CTLA-4 inhibitors. These studies will be used to identify immune biomarkers that reflect functional B cell activity in melanoma tumors and may help guide immunotherapy selection.
