Summary
A medRxiv preprint reports improved clinical outcomes and changes in immune markers after N-acetylcysteine treatment in cancer patients with severe COVID-19. The clinical comparison used severity-matched patients treated before the trial began.
A medRxiv preprint reports that N-acetylcysteine treatment was associated with improved clinical outcomes and changes in immune activity among cancer patients hospitalized with severe COVID-19. The prospective phase II study compared treated patients with disease severity-matched patients hospitalized shortly before the trial began; the preprint also describes laboratory analyses and two mouse models of severe respiratory viral infection.
What the researchers found
The research team first used proteomic and metabolomic profiling to compare matched groups of cancer and non-cancer patients, with and without COVID-19. They identified disrupted cysteine metabolism as a feature associated with severe COVID-19 in the cancer group. This analysis points to an association; the treatment findings came from a separate clinical trial.
In that trial, patients with cancer and steroid-refractory severe COVID-19 received N-acetylcysteine (NAC), a source of cysteine involved in cellular redox processes. The researchers report improved clinical outcomes relative to severity-matched hospitalized patients treated in the period immediately before trial initiation. They also report lower circulating markers of innate inflammation, fewer severe-disease-associated MHC-II-low monocytes, and more circulating CD8 T cells, with increased activation and effector differentiation. CD8 T cells are immune cells that can target infected cells.
The proposed mechanism links metabolism to immune-cell behaviour. The team reports that NAC reduced prostaglandin E2-driven interactions between suppressive monocytes and T cells. In their analyses, those interactions limited T-cell expansion and development into effector cells. NAC also reduced activity of redox-sensitive transcription factors, including KLF6, which the researchers link to clonal expansion and effector differentiation. Similar increases in lung-infiltrating CD8 T cells were reported in two mouse models of severe respiratory viral infection.
How to interpret the clinical result
The trial was conducted at a single institution and included adults hospitalized with severe COVID-19. Its two groups covered patients who were mechanically ventilated or in intensive care, and patients needing supplemental oxygen but not already in intensive care. The clinical comparison described in the preprint was with patients treated before the trial, rather than a concurrent randomized control group. That design makes it harder to separate the treatment’s contribution from other differences between the periods.
The report is a preprint, and the abstract does not give the number of patients treated, the NAC dose, or numerical effect estimates and defined clinical endpoints. Those details are important for judging the size and reliability of the reported clinical benefit. The immune findings offer a possible biological explanation for the result, but the mouse experiments are supporting evidence from animals, not a measure of treatment benefit in people.