Immunotherapy, radiation therapy triggers favorable response in patients with late-stage cancer
A Phase II trial presented today at ASTRO showed that patients with stage IV cancer that had spread to the lungs or liver had a favorable response to treatment with radiation therapy and immunotherapy.
“This combination of immunotherapy and radiation therapy was safe and well-tolerated by patients with late-stage cancers. We were surprised that a large percentage of patients achieved stable disease several months after treatment—meaning that while their tumors didn’t shrink, they did stop growing,” lead author Dr. James Welsh said in prepared remarks.
“It appears that the radiation helped turn the tumor into a vaccine to stimulate an immune response. This heightened immune response was able to keep the tumors stable. Longer follow-up is needed to determine if this benefit of stable disease will endure over time.”
The Phase II trial enrolled 100 patients to evaluate the combination of high-dose radiation therapy and immunotherapy.
The whole group of patients received four cycles of ipilimumab and stereotactic body radiation therapy to the site or sites of metastasis in either the liver or the lungs. Randiation therapy was given either concurrently with or sequentially to immunotherapy, the researchers noted.
Patients were enrolled into one of five cohorts: concurrent lung, sequential-Gy lung, concurrent liver, sequential 50-Gy liver and sequential 60-Gy liver or lung.
Half of the patients in the sequential 50-Gy lung cohort experienced disease stability, as well as 45% of the concurrent-lung group, 35% of the concurrent liver group and 30% of the sequential 50-Gy liver group. In the larger-lesion, higher-dose radiation group, 60% of patients had a favorable response to treatment.
Median progression-free survival for all patients following radiation therapy combined with immunotherapy was five months and median overall survival was 12 months.
There were no complete responses to treatment, the researchers reported, but three patients who received SBRT concurrently with immunotherapy had a partial response.
“A small percentage of patients experienced a potential abscopal effect, where tumors that were not irradiated became smaller after we treated different sites with radiation,”Welsh said. “For example, one patient with anaplastic thyroid cancer—one of the deadliest types of cancer—experienced a reduction in the primary tumor after we irradiated a lung metastasis. This patient had controlled disease for more than 13 months.
“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. In fact, there may be additional benefit from combining the therapies in terms of improved disease control. Follow-up research in larger clinical trials is needed to determine which types of tumors and patients will respond best to this immunotherapy-radiation approach.”
