Low-Dose Whole-Lung Radiation for COVID-19 Pneumonia

Background Safety of whole-lung low-dose radiation therapy (LD-RT) for COVID-19 pneumonia has been established in two phase I trials. By focally dampening pulmonary cytokine hyperactivation, LD-RT may improve outcomes in hospitalized and oxygen-dependent COVID-19 patients. Methods Patients with COVID-19 pneumonia were treated with 1.5 Gy whole-lung LD-RT, followed for 28 days or at least until hospital discharge, and compared to an age- and comorbidity-matched control cohort. COVID-19-positive patients eligible for this protocol were hospitalized, had radiographic consolidations, and required supplemental oxygen. Efficacy endpoints were time to clinical recovery, radiographic improvement, and serologic responses. Results Ten patients received whole-lung LD-RT between April 24 and May 24, 2020 and were compared to ten matched control patients, of whom six received COVID-directed therapy. Median time to clinical recovery was 12 days for the control cohort vs 3 days for LD-RT (HR 2.9, p=0.05). Median time to hospital discharge (20 and 12 days, p=0.19), and intubation rates (40% and 10%, p=0.12) were shorter for the LD-RT cohort. The LD-RT cohort had faster radiographic improvement (p=0.03), even among patients with high COVID burden. Serologic recovery in specific hematologic, cardiac, hepatic, clotting, and inflammatory markers occurred more rapidly following LD-RT than among matched controls. Conclusions Strong efficacy signals, including a 3-fold risk reduction in time to clinical improvement, were observed following LD-RT compared to matched patients receiving COVID-directed therapy for COVID-19 pneumonia. Given the global availability of radiation accelerators, ongoing international efforts to investigate the optimal role of LD-RT in COVID-19 pneumonia are justified. Clinical Trial Registration NCT04366791.