CONSOLIDATIVE RT FOR LIMITED METASTATIC NSCLC

In a single-institution phase II trial reported in JAMA Oncology, Iyengar et al found that consolidative stereotactic ablative radiotherapy improved progression-free survival vs maintenance therapy alone in patients with limited metastatic non–small cell lung cancer (NSCLC).

Study Details

In the study, 29 patients from The University of Texas Southwestern Medical Center with limited metastatic NSCLC (primary plus up to 5 metastatic sites) without targetable EGFR or ALK mutations who had a partial response or stable disease after induction chemotherapy were randomized to receive stereotactic ablative radiotherapy followed by maintenance chemotherapy (n = 14) or maintenance therapy alone (n = 15).

Radiotherapy was delivered to all sites of gross disease. The most commonly used induction chemotherapy regimen was carboplatin plus pemetrexed (Alimta; 48%), and the most common maintenance regimen was pemetrexed monotherapy (62%). The primary endpoint was progression-free survival.

Progression-Free Survival and Toxicity

The trial stopped accrual early after interim analysis found a significant improvement in progression-free survival in the radiotherapy group (median = 9.7 vs 3.5 months, hazard ratio = 0.304, P = .01). At the time of analysis, disease progression had occurred in 10 of 15 patients in the maintenance chemotherapy-alone group; among them, 7 had disease progression at the original sites of gross tumor. Disease progression occurred in 4 of 14 patients in the radiotherapy group, with no disease progression observed within radiation fields.

Four grade 3 toxicities considered at least probably related to study treatment occurred in the radiotherapy group, and two grade 3 toxicities and one grade 4 toxicity were observed in the maintenance chemotherapy–alone group.

The investigators concluded: “Consolidative [stereotactic ablative radiotherapy] prior to maintenance chemotherapy appeared beneficial, nearly tripling [progression-free survival] in patients with limited metastatic NSCLC compared with maintenance chemotherapy alone, with no difference in toxic effects. The irradiation prevented local failures in original disease, the most likely sites of first recurrence. Furthermore, [progression-free survival] for patients with limited metastatic disease appeared similar to those patients with a greater metastatic burden, further arguing for the potential benefits of local therapy in limited metastatic settings.”

Puneeth Iyengar, MD, PhD, of the Department of Radiation Oncology, University of The Texas Southwestern Medical Center, is the corresponding author of the JAMA Oncology article.