A pilot phase Ib/II study of whole-lung low dose radiation therapy (LDRT) for the treatment of severe COVID-19 pneumonia: First experience from Africa

Background Low dose radiation therapy (LDRT) has been used for non-malignant conditions since early 1900s based on the ability of single fractions between 50-150 cGy to inhibit cellular proliferation. Given scarcity of resources, poor access to vaccines and medical therapies within low and middle income countries, there is an urgent need to identify other cost-effective alternatives in management of COVID-19 pneumonia. We conducted a pilot phase Ib/II investigator- initiated clinical trial to assess the safety, feasibility, and toxicity of LDRT in patients with severe COVID-19 pneumonia at the Aga Khan University Hospital in Nairobi, Kenya. Additionally, we also assessed clinical benefit in terms of improvement in oxygenation at day 3 following LDRT and the ability to avoid mechanical ventilation at day 7 post LDRT. Methods Patients with both polymerase chain reaction (PCR) and high-resolution computer tomogram (HRCT) confirmed severe COVID-19 pneumonia, not improving on conventional therapy including Dexamethasone and with increasing oxygen requirement were enrolled in the study. Patients on mechanical ventilation were excluded. Eligible patients received a single 100cGy fraction to the whole lung. In the absence of any dose limiting toxicity the study proposed to treat a total of 10 patients. The primary endpoints were to assess the safety/feasibility, and toxicity within the first 24 hours post LDRT. The secondary endpoints were to assess efficacy of LDRT at Day 3, 7, 14 and 28 post LDRT. Results Ten patients were treated with LDRT. All (100%) of patients were able to complete LDRT without treatment related SAE within the first 24 hours post treatment. None of the patients treated with LDRT experienced any acute toxicity as defined by change in clinical and respiratory status at 24hr following LDRT. Majority (90%) of patients avoided mechanical ventilation within 7 days of LDRT. Four patients (40%) demonstrated at least 25% improvement in oxygen requirements within 3 days. Six patients (60%) were discharged and remained off oxygen, whereas four progressed and died (1 due to sepsis and 3 in cytokine storm). Median time to discharge (n = 6) was 16.5 days and median time to death (n = 4) was 11.0 days. Patients who ultimately died showed elevated inflammatory markers including Ferritin, CRP and D-dimers as compared to those who were discharged alive. Conclusion LDRT was feasible, safe and shows promise in the management of severe COVID-19 pneumonia including in patients progressing on conventional systemic treatment. Additional phase II trials are warranted to identify patients most likely to benefit from LDRT.