Radiotherapy boosts efficacy of ipilimumab in metastatic melanoma

May 1, 2012

Although ipilimumab (Yervoy, Bristol-Myers Squibb) has been a tremendous advance for patients with metastatic melanoma, only a subset of patients benefits from treatment.

Key Points

As researchers continue to study the effects of adjunctive therapies with ipilimumab, however, a recent report suggests radiotherapy may increase its efficacy, according to Michael A. Postow, M.D., medical oncology fellow, Memorial Sloan-Kettering Cancer Center, New York.

Dr. Postow is part of a team led by medical oncologist and immunologist Jedd D. Wolchok, M.D., Ph.D., that reported in the New England Journal of Medicine a case of a woman with metastatic melanoma (Postow MA, Callahan MG, Barker CA, et al. N Engl J Med. 2012;366(10):925-931).

The patient had been enrolled in a clinical trial and treated with ipilimumab as part of her treatment, which failed to halt the spread of the disease. However, after she received palliative radiotherapy for back pain resulting from a paraspinal mass, her targeted paraspinal mass as well as lesions outside the irradiated area remarkably regressed.

"What made this case particularly interesting to us is that this is the first time that we have seen that there was a clear, documented case where someone really benefited with a combination of radiotherapy when it was administered with ipilimumab," Dr. Postow says.

Researchers hope this finding will lead to further investigation of possible mechanisms of synergy between the two anticancer treatments and potentially increase the number of patients benefiting from ipilimumab.

The patient's response after radiotherapy hinted that radiotherapy may have boosted the efficacy of ipilimumab.

"It's a little bit different in our patient because she had been getting ipilimumab for quite a long time, and it hadn't been working as we had been hoping, in that her tumors were slowly increasing in size," Dr. Postow says.

"It wasn't until the radiation was delivered that her tumors started to regress and decrease in size," he says.

The medical literature reports a rare occurrence known as the abscopal effect, resulting in regression of tumors outside the irradiated area when radiotherapy is targeted to one tumor area, Dr. Postow says.