Stable disease was achieved for half of the patients in the sequential 50-Gy lung cohort, 45 percent of the concurrent-lung group, 35 percent of the concurrent liver group and 30 percent of the sequential 50-Gy liver group. Sixty percent of patients in the larger-lesion, higher-dose radiation group demonstrated a favorable response to treatment.

The median progression-free survival (PFS) for all patients following radiation therapy combined with immunotherapy was five months (95% CI = 2.7-7.2 months). Median overall survival (OS) was 12 months (95% CI = 9.3-14.6 months). Patients who received sequential radiation to lung metastases rather than to liver metastases had better PFS (p = 0.055, 95% CI = 3.7-6.4) and OS (p = 0.059, CI = 7.9-20.0). No differences were found between the concurrent lung or liver groups for progression-free (p = 0.2) or overall (p = 0.3) survival.


There were no complete responses to treatment, but a partial response was found for three patients who received SBRT concurrently with ipilimumab, including two patients (10%) on the concurrent lung arm and one patient (5%) on the concurrent liver arm. No patients in the sequential radiation groups experienced 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," explained Dr. Welsh. "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."

Lesions from non-small cell lung cancer (NSCLC) were most responsive to the combined treatment; two thirds of these patients had a favorable response (partial response or stable disease) following SBRT plus immunotherapy. Response to treatment was scored using immune-related criteria (irRC). Partial response represented a 50 percent or greater decrease in tumor size. Progressive disease represented a 25 percent increase in tumor size. Stable disease responses included those that did not fall into complete, partial or progressive response categories.

No patients experienced Grade 4 or 5 treatment-related side effects. Twenty-seven patients experienced Grade 3 toxicities related to immunotherapy, including colitis (8 patients), diarrhea (7 patients), rash (4 patients), elevation of liver enzymes (3 patients), hypophysitis (3 patients), elevation of bilirubin (1 patient) and intestinal obstruction (1 patient). Two patients experienced Grade 3 toxicities related to combination therapy, including one patient with an increase in liver enzymes and one patient with pneumonitis. Side effects were evaluated using the Common Terminology Criteria for Adverse Events, version 4.0.

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