Many patients with stage IV metastatic cancer achieve stable disease after treatment with radiation therapy and immunotherapy, according to findings of a study presented at the American Society for Radiation Oncology (ASTRO) annual meeting (September 24-27, 2017; San Diego, CA).
James Welsh, MD associate professor of radiation oncology, University of Texas MD Anderson Cancer Center, and colleagues conducted a study to assess the efficacy of combining radiation therapy and immunotherapy in 100 patients with stage IV metastatic lung or liver cancer. Patients included were resistant to standard therapies, exhibited at least one lesion in the liver or lung that could be responsive to stereotactic radiation, and at least one metastasis not toughing the lung or liver lesion.
All patients were given four cycles of ipilimumab (3 mg/kg every 3 weeks) and stereotactic body radiation therapy (SBRT) to their sites of metastasis. Radiation therapy was administered either concurrently with or sequentially to immunotherapy. Patients were directed into any of five treatment cohorts: concurrent lung, sequential (50 Gy) lung, concurrent liver, sequential (50 Gy) liver, or sequential (60 Gy) liver or lung for those with larger metastasis. A total of 20 patients were in each arm.
Results of the study showed that stable disease was achieved in 50% of patients on the sequential (50 Gy) arm, 45% of patients on the concurrent lung arm, 35% of patients on the concurrent liver arm, and 30% of patients on the sequential (50 Gy) liver arm. Sixty percent of patients on the sequential (60 Gy) liver or lung arm demonstrated a favorable response to treatment.
No complete responses to treatment were observed, but a partial response was found for three patients who received SBRT concurrently with immunotherapy, including two patients on the concurrent lung arm and one patient on the concurrent liver arm. No patients on any of the sequential radiation arms experienced a partial response.
"We found that the addition of SBRT for patients who are on immunotherapy to be safe and well-tolerated, meaning that radiation oncologists can feel confident continuing immunotherapy for most patients when adding SBRT to lung or liver metastases,” said Dr Welsh in his presentation. “In fact, there may be additional benefit from combining the therapies in terms of improved disease control.”
Further research is needed in larger clinical trials to assess which tumor types will respond best to this treatment approach.—Zachary Bessette