A recent melanoma case featuring the abscopal effect, in which local radiotherapy delivered to a single tumor results in the regression of metastatic cancer at a distance from the irradiated site, may lay the groundwork for a promising approach to melanoma treatment.

Although the abscopal effect is extremely rare, it has been described in several cases of melanoma, lymphoma, and kidney cancer, according to a statement from Memorial Sloan-Kettering Cancer Center (MSKCC) in New York, New York. MSKCC medical oncologist Jedd Wolchok, MD, PhD, was senior author of the report describing the recent case (N Engl J Med. 2012;366-925931).

“We are excited about these results, and what we have seen in this one patient proves the principle that adding radiation therapy to immunotherapy may be a promising combination approach to treatment for advanced cancer,” commented Wolchok.

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Wolchok’s team used ipilimumab, an immunotherapy, to treat a patient with advanced melanoma. Approved by the FDA in March 2011, ipilimumab is the first drug to demonstrate improved overall survival in persons with advanced melanoma. This monoclonal antibody works by inhibiting an immunologic checkpoint on T cells known as cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4).

Over time, Wolchok’s patient’s melanoma had metastasized to the spleen, lymph nodes, and near the spine. When localized radiation was administered to the tumor near the spine to provide pain relief, the targeted tumor shrank significantly—and, unexpectedly, so did the tumors in the spleen and the lymph nodes, even though those sites were not directly targeted by the radiation therapy. The use of radiation therapy also resulted in other changes that allowed the patient’s immune system to recognize and control the cancerous cells more effectively.

The researchers followed the patient from her initial diagnosis of melanoma in 2004 through a series of treatments and eventual disease regression in April 2011 after a combination treatment of radiation and immunotherapy.