A systemic complete response of metastatic melanoma to local radiation and immunotherapy

Abstract

Background: Melanoma is a relatively immunogenic tumor, in which infiltration of melanoma cells by T lymphocytes is associated with a better clinical prognosis. We hypothesized that radiation-induced cell death may provide additional stimulation of an anti-tumor immune response in the setting of anti-CTLA-4 treatment.

Methods: In a pilot melanoma patient, we prospectively tested this hypothesis. We treated the patient with two cycles of ipilimumab, followed by stereotactic ablative radiotherapy to two of seven hepatic metastases, and two additional cycles of ipilimumab.

Results: Subsequent positron emission tomography-computed tomography scan indicated that all metastases, including unirradiated liver lesions and an unirradiated axillary lesion, had completely resolved, consistent with a complete response by RECIST.

Conclusion: The use of radiotherapy in combination with targeted immunotherapy as a noninvasive in vivo tumor vaccine strategy appears to be a promising method of enhancing the induction of systemic immune responses and anti-tumor effect.

Figure 1

PET scans performed before treatment (row 1), at 6 months after treatment (row 2), and at 12 months after treatment (row 3). Column A (arrow) shows untreated axillary lesion that was no longer apparent at 6 and 12 months after treatment. Column B (arrow) shows one of two treated hepatic lesions, which showed complete response to treatment at 6 and 12 months after treatment. Column C (arrows) shows three of five untreated hepatic lesions, which also showed complete response to treatment at 6 and 12 months after treatment.