Low Dose Radiotherapy in the Management of COVID-19 Pneumonia (LOWRAD-Cov19): Final Results

PURPOSE/OBJECTIVE(S): To evaluate the results of LD-RT to lungs in the management of patients with COVID-19 pneumonia. MATERIALS/METHODS: We conducted a prospective phase I-II trial enrolling COVID-19 patients ≥50 years-old, with bilateral lung involvement at imaging study and oxygen requirement. Patients received 1 Gy to whole lungs in a single fraction. Primary outcome was radiological response assessed as severity and extension scores at days +3 and +7. Secondary outcomes were toxicity (CTCAE v5.0), days of hospitalization, changes in inflammatory blood parameters (ferritin, lymphocytes, C-reactive protein, d-dimer and LDH) and SatO2/ FiO2 index (SAFI), at day +3 and +7. Descriptive analyses were summarized as means with standard deviation (SD) and/or medians with interquartile ranges (IQR). A Wilcoxon sign rank test for paired data was used to assess the CT scores and Chi Square was used to assess for comparison of categorical variables. RESULTS: Forty-one patients were included. Median age was 71 (IQR 60-84). Eighteen patients (47%) previously received any antiCOVID treatment (tocilizumab, lopinavir/ritonavir, remdesivir) and thirty-two patients (84%) received steroids during LD-RT. Extension score improved significantly (p=0.02) on day +7 and SAFI on day +3 and + 7 (p<0.01). Median SAFI on day 0 was 147 (IQR 118-264), 230 (IQR 120-343) on day +3 and 293 (IQR 121-353) on day +7. Significant decrease was found in C-reactive protein on day +7 (p=0.02) and in lymphocytes counts on day +3 and +7 (p=0.02). Median number of days in hospital after RT was 11 (range 4-78). With a median follow-up of 60 days after LD-RT, 26 (63%) patients were discharged, 11 (27%) died because of COVID respiratory failure and 4 (10%) died of other causes. CONCLUSION: LD-RT is a feasible and well-tolerated treatment that may lead to rapid clinical improvement. Large randomized trials should be done to establish the efficacy of LD-RT to treat COVID-19 pneumonia.