Melanoma is the fifth most common cancer in the United Kingdom and one of the most dangerous forms of skin cancer when it spreads beyond the skin. Checkpoint inhibitors have transformed care by releasing molecular brakes that normally restrain T cells, allowing these immune cells to recognise and attack tumour cells. T cells can directly kill cancer cells or coordinate broader immune activity, while B cells produce antibodies and can also present tumour-related antigens to T cells. Although B cells have historically received less attention in cancer immunology than T cells, growing evidence suggests that they can influence whether immunotherapy succeeds. Subject of Research: PeopleArticle Title: Circulating B cell and T cell activation states predict clinical outcomes in melanoma and reveal dynamic immune reinvigoration with checkpoint inhibitor immunotherapyWeb References: Journal for ImmunoTherapy of Cancer study; King’s College London research backgroundReferences: DOI: 10.1136/jitc-2026-015585Keywords: melanoma, immunotherapy, checkpoint inhibitors, B cells, T cells, immune profiling, mass cytometry, cancer immunology, treatment response, immune-related side effects