Symptom relief and cytokine modulation by clarithromycin in mild COVID-19 pneumonia: an exploratory, multicenter, randomized-controlled open-label trial (CAME-COVID study)

Background: Coronavirus disease 2019 (COVID-19) remains an epidemic worldwide, and long COVID is a major social concern. Therapeutic options for relieving symptoms of COVID-19 pneumonia are limited. Clarithromycin (CAM), a macrolide antimicrobial, also functions as an immunomodulator. Objectives: To assess the efficacy of CAM in improving clinical symptoms and attenuating inflammation in patients with mild COVID-19, with the aim of preventing progression to severe disease. Design: An exploratory, multicenter, randomized-controlled, open-label trial. Methods: This trial enrolled patients with mild COVID-19 pneumonia without oxygen supplementation from May 2021 through February 2022 in eight hospitals in Japan. Patients were randomly assigned in a 1:1:1 ratio to groups A (CAM 800 mg/day, 7 days), B (CAM 400 mg/day, 7 days), or C (standard treatment). The primary endpoint was the number of days required for 50% improvement in seven symptoms (fatigue, headache, cough, shortness of breath, taste/smell disturbance, and general unwellness) based on severity scores. Secondary endpoints included inflammatory cytokines, viral load, immunoglobulins, and pneumonia infiltrations. Results: A total of 56 patients were enrolled and randomized. The primary endpoint did not differ significantly between groups (A: 5.0 days, B: 4.0 days, C: 4.0 days), though the seven symptoms tended to disappear earlier in group A than group C ( p = 0.08), and fatigue significantly decreased in group A ( p = 0.005). Serum inflammatory cytokines, tumor necrosis factor (TNF)-α, granulocyte colony stimulating factor (G-CSF), interleukin (IL)-7, IL-15, and proliferation factors, transforming growth factor (TGF)-α, fibroblast growth factor (FGF)-2, and fms-like tyrosine kinase 3 ligand (Flt3-L), significantly decreased in group A. IL-8 and IFN-γ in nasal drip significantly decreased in both group A and B. Serious adverse events did not increase in CAM groups, though mild gastrointestinal and liver events occurred in group A. Conclusion: CAM is safe and potentially useful for improving partial COVID-related symptoms and exerting immunomodulation during COVID-19 pneumonia. Trial registration: Japan Registry of Clinical Trials (jRCT; registration number: jRCTs071210011; https://jrct.mhlw.go.jp/latest-detail/jRCTs071210011 ) on April 13, 2021.