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ASTRO 2015: Subset of Patients With Metastatic Melanoma Achieves Clinical Benefit From Combination of Immunotherapy and Radiation Therapy

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Key Points

  • In this study, 20 patients with stage IV melanoma were treated with palliative radiation therapy and intravenous ipilimumab (3 mg/kg) every 3 weeks, for a total of four treatment cycles. Radiation therapy was initiated to one or two sites of metastatic melanoma within 5 days of the initial immunotherapy treatment.
  • At a median follow-up of 38 weeks, 11 patients (55%) had an initial response to therapy.
  • Of the 11 patients who responded to the immunotherapy, 1 had an ongoing systemic complete response to the combination therapy at a median follow-up of 39 weeks. Three patients had a partial response to therapy for a median of 38 weeks, and 5 patients had stable disease as best response for a median of 36 weeks.

Immunotherapy combined with palliative radiation therapy for a subset of patients with metastatic melanoma reduces the growth and spread of the cancer, according to research presented by Hiniker et al (Abstract 215) on October 20, 2015 at the American Society for Radiation Oncology’s (ASTRO’s) 57th Annual Meeting in San Antonio, Texas.

Although melanoma is not the most common type of skin cancer, it is the most serious type. Immunotherapy, typically with ipilimumab (Yervoy), is often combined with other cancer therapies to aid in the treatment of stage IV melanoma. 

Study Details

This phase II clinical trial is one of the first prospective clinical trials to report results from the treatment of metastatic melanoma with the combination of radiation therapy and systemic immunotherapy. In this study, 20 patients with stage IV melanoma were treated with palliative radiation therapy and intravenous ipilimumab (3 mg/kg) every 3 weeks, for a total of four treatment cycles. Radiation therapy was initiated to one or two sites of metastatic melanoma within 5 days of the initial immunotherapy treatment. All patients had at least one nonirradiated site of metastasis that could be used for assessment of response to therapy.

Patients had blood drawn during and after treatment to determine if there was evidence of an immune response developing in response to the therapy. Baseline tumor imaging studies were completed prior to treatment, and follow-up assessments were completed 2 to 4 weeks following the fourth dose of immunotherapy, and every 3 months until disease progression was detected. Response Evaluation Criteria in Solid Tumors (RECIST) and Immune Response Criteria (IRC) guidelines were used to score responses based on tumor measurements.

Study Findings

At a median follow-up of 38 weeks, 11 patients (55%) had an initial response to therapy—including complete and partial responses, as well as stable disease. Of the 11 patients who responded to the immunotherapy, 1 patient (9.1%) had an ongoing systemic complete response to the combination therapy at a median follow-up of 39 weeks. Three patients had a partial response to therapy for a median of 38 weeks (range, 26–52 weeks), and 5 patients had stable disease as best response for a median of 36 weeks (range, 26–76 weeks). The nine other patients had progressive disease as defined by RECIST on the first treatment scan.

Additionally, an analysis of blood markers in a subset of patients identified immune markers that appeared to correlate with responses. The initial data suggest that immune response markers in the peripheral blood may hold promise in helping to distinguish responders from nonresponders, for purposes of facilitating better patient selection for treatment and early detection of potentially meaningful immune responses to therapy.

“We were impressed that half of the patients appeared to have benefited from this combination therapy, many with durable responses to therapy,” said Susan Hiniker, MD, Instructor in the Department of Radiation Oncology at Stanford University School of Medicine. “Current data show that three patients have had an ongoing complete response to therapy, which suggests that the combination of immunotherapy plus radiation can be extremely effective in a subset of patients.”

She continued, “Our results suggest that local radiation therapy can be safely and effectively combined as a component of in situ tumor vaccine strategies with the new potent class of immunotherapy drugs that are revolutionizing the treatment of metastatic melanoma and other difficult-to-treat cancers. These data also suggest that radiation may potentiate the effects of this new class of immune-targeting medication and support the design of larger trials to further investigate potential synergy between radiotherapy and immunotherapy in the treatment of cancer.”

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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