A randomized, double-blind, placebo-controlled trial of IL-7 in critically ill patients with COVID-19.

Summary

In a double-blind RCT (n=109) of critically ill COVID-19 patients with lymphopenia, recombinant IL-7 (CYT107) was safe, reduced treatment-emergent adverse events, and decreased hospital-acquired infections by 44% compared to placebo. Although the primary endpoint of lymphocyte recovery was not significantly different overall, a trend favored IL-7 in patients not receiving concomitant antivirals.

Key Findings

• CYT107 (IL-7) was well tolerated with no cytokine storm or pulmonary function worsening.
• Treatment-emergent adverse events were significantly fewer in IL-7 versus placebo (P < 0.001).
• Hospital-acquired infections were reduced by 44% with IL-7 (P = 0.014).
• Overall lymphocyte recovery did not differ, but trended higher (+43%) without concomitant antivirals (P = 0.067).

Clinical Implications

Consider IL-7 as an adjunct in clinical trials for critically ill viral pneumonia with lymphopenia to reduce secondary infections; monitor concomitant antivirals as potential effect modifiers.

Limitations

• Primary endpoint (lymphocyte recovery) was not met overall
• Modest sample size limits power for mortality and subgroup analyses

Future Directions

Larger, stratified trials across respiratory viral pathogens to confirm infection reduction, explore mortality effects, and define interaction with antivirals.