ASTRO 2024: Combination of High-Dose Radiotherapy and Immunotherapy for Metastatic NSCLC

By: Jenna Carter, PhD
Posted: Monday, October 14, 2024

Radiotherapy plus immune checkpoint inhibition may have synergistic anticancer effects in patients with metastatic non–small cell lung cancer (NSCLC); however, the impact of this treatment combination is not well understood in this population. A study presented at the 2024 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 192) used data from the RRADICAL trial (ClinicalTrials.gov identifier NCT03176173) to assess whether the addition of high-dose radiation therapy to immune checkpoint inhibition could prolong progression-free survival. Nikhil Kotha, MD, of Stanford University School of Medicine, California, and colleagues reported that the primary outcome of 24-week progression-free survival was 60% with the combination strategy, which was higher than the historic control rate.

A total of 44 patients with NSCLC were included in this study. Patients received anti–PD-1/anti–PD-L1 immune checkpoint inhibition for 4 or more weeks from July 2017 to May 2021. Study inclusion required that imaging after initiation of immune checkpoint inhibition showed partial response, stable disease, or modest disease progression. During the study, patients received high-dose radiotherapy to one to four extracranial tumors and continued immunotherapy until disease progression or unacceptable toxicity.

Findings revealed that 75% of patients had adenocarcinoma, and 64% had polymetastatic disease; 82% were treated with pembrolizumab. The 24-week progression-free survival rate was 60% (95% confidence interval [CI] = 44%–75%) higher than the historic control rate (P < .001). Median progression-free survival was 6.9 months (95% CI = 4.0–13.5 months), and median overall survival was 27.4 months (95% CI = 20.4 months to not reached). Additionally, there were several patients with prestudy disease progression on immunotherapy alone who achieved durable responses (up to 56 months) with the addition of radiotherapy. Furthermore, the local tumor recurrence rate was low, with a cumulative incidence of 5% at 1, 2, and 3 years.

Disclosure: Dr. Kotha reported no conflicts of interest.

2024 ASTRO Annual Meeting

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