A study found that the physical arrangement of immune cells inside melanoma tumors plays a key role in determining whether immunotherapy works.
Researchers analyzed tumor samples from patients in the SWOG S1616 clinical trial using advanced imaging and genetic tools. They discovered that patients who responded to treatment had active CD8 T cells clustered close to cancer cells and near blood vessels, allowing them to attack tumors effectively. In contrast, non-responding tumors contained dense clusters of plasma cells and showed weak T-cell activity, limiting the immune response.
These findings suggest that tumor structure—not just genetic mutations—can predict treatment success. The study may help doctors better select patients for immunotherapy and develop strategies to reshape resistant tumors, improving outcomes for those with advanced melanoma.