Acute SARS-CoV-2 infection results in high mortality rates in patients with cancer with patients dying from a combination of virus and inflammation-driven respiratory failure. We conducted a two-arm, single-institution phase II study of N-acetylcysteine in patients admitted to Memorial Sloan Kettering Cancer Center with severe COVID-19 from May 2020 to April 2021. A total of 42 patients were treated: 13 patients in arm A (ICU) and 29 patients in arm B (non-ICU). In total, 23% of patients in arm A and 69% of patients in arm B met the predetermined clinical definition of treatment success. Patients meeting a successful primary endpoint were more likely to exhibit decreases in systemic levels of interleukin-6 and C-reactive protein and had both higher proportions of PD-1-expressing effector memory and fewer terminally differentiated CD8+ T-cells. These results suggest that many patients with cancer and severe COVID-19 experience clinical and immunologic improvement with N-acetylcysteine therapy.
