Effective September 26, 2023, NRG Oncology-RTOG 1308, a phase III randomised trial comparing overall survival after photon versus proton chemoradiotherapy for patients with inoperable stage II-IIIB non-small cell lung cancer (NSCLC) has met its accrual target.

The trial, one of several NRG Oncology ongoing clinical trials across various malignancies within the National Clinical Trials Network (NCTN) that compare photon versus proton radiation therapy techniques, is the first phase III head-to-head comparison of these radiation methods to meet accrual.

After stratifying patients by stage, histology, concurrent chemotherapy doublet type, and planned use of immunotherapy, the trial randomised patients with clinical American Joint Committee on Cancer (AJCC) 7th edition inoperable stage II, IIIA, or IIIB disease to either 70 Gy (relative biological effectiveness, RBE) of photon or proton radiation therapy [2 Gy (RBE) once daily] plus standard-of-care platinum-based doublet chemotherapy.

Following chemoradiotherapy, both groups receive standard-of-care consolidation systemic treatment.

Of a total of 330 patients enroled (328 from participating institutions in the United States and 2 from Switzerland), 158 were randomised to the photon group and 172 to the proton group.

The study opened to accrual in February 2014 and accrued its first patient in April 2014.

The study is designed to assess whether proton therapy will improve the rate of overall survival and decrease the rate of treatment-related cardiac toxicity compared to standard photon therapy for patients with inoperable locally advanced NSCLC.

The study’s co-primary objectives compare overall survival and treatment-related cardiac toxicity/lymphocyte reduction across the treatment groups.

Secondary objectives include 2-year progression-free survival; development of grade 3 or higher adverse events not related to cardiac and lymphocyte toxicity; quality of life; cost-effectiveness; pulmonary function changes; and an exploration of clinically relevant technological parameters to ensure quality and effectiveness throughout radiation therapy processes, including imaging, simulation, patient immobilisation, target and critical structure definition, treatment planning, image guidance and delivery.

“The completion of accrual to the NRG Oncology-RTOG 1308 study brings the oncology community one step closer to a definitive comparison between photon and proton radiation therapy techniques in patients with inoperable locally advanced NSCLC,” stated Zhongxing Liao, MD, of the University of Texas MD Anderson Cancer Center and lead investigator of the study.

“My co-investigators and I look forward to the maturation of results so that we can continue to refine evidence-based treatment decisions on radiation approach in this patient population, and we are immensely grateful to the staff and patients who participated in the trial to lead us to this point.”

A read-out of the primary endpoint results is anticipated to be complete in December 2026, with secondary endpoint analyses expected the year afterwards.

Source: NRG Oncology