Abscopal Effect in a Patient with Melanoma

To the Editor: Postow et al. (March 8 issue) 1 report an abscopal effect in a patient with melanoma treated with ipilimumab and radiotherapy, with a response in nonirradiated lesions. We have hypothesized that the radiation-induced death of tumor cells may stimulate an antitumor immune response in a patient receiving treatment with anti–cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4) antibody. We prospectively tested this hypothesis in a pilot study of a patient with melanoma. The patient was treated with two cycles of ipilimumab, followed by stereotactic radiotherapy to two of eight hepatic metastases and two additional cycles of ipilimumab. Remarkably, subsequent positron-emission tomography–computed . . .