Immunologic Correlates of the Abscopal Effect in a Patient with Melanoma

TLDR

The abscopal effect describes regression of distant metastatic lesions following local radiotherapy, potentially driven by immune activation, and is enhanced by CTLA‑4 blockade with ipilimumab. We report a case of the abscopal effect in a melanoma patient treated with ipilimumab and radiotherapy. Temporal associations included tumor shrinkage with NY‑ESO‑1 antibody responses, changes in peripheral blood immune cells, and increased antibody responses to other antigens after radiotherapy. Funding was provided by the National Institutes of Health and other agencies.

Abstract

The abscopal effect is a phenomenon in which local radiotherapy is associated with the regression of metastatic cancer at a distance from the irradiated site. The abscopal effect may be mediated by activation of the immune system. Ipilimumab is a monoclonal antibody that inhibits an immunologic checkpoint on T cells, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4). We report a case of the abscopal effect in a patient with melanoma treated with ipilimumab and radiotherapy. Temporal associations were noted: tumor shrinkage with antibody responses to the cancer-testis antigen NY-ESO-1, changes in peripheral-blood immune cells, and increases in antibody responses to other antigens after radiotherapy. (Funded by the National Institutes of Health and others.)