The Food and Drug Administration (FDA) has issued a statement regarding leronlimab, an investigational monoclonal antibody for COVID-19, following the release of trial results from the product developer CytoDyn.

“Although FDA generally cannot disclose confidential information about unapproved products, we have concluded that given the significant public interest in leronlimab, it is important to provide summary information about the status of the CytoDyn development program,” the Agency explained in the communication.

Two separate clinical trials were conducted to assess the safety and efficacy of leronlimab: CD10 ( NCT04343651), a randomized, double-blind, placebo-controlled, phase 2 trial in patients with mild to moderate COVID19 (N=86), and CD12 ( NCT04347239), a randomized, double-blind, placebo-controlled, adaptive design, phase 2b/3 trial in patients with severe or critical COVID-19 (N=394).

Results from the CD10 trial showed that leronlimab did not meet the primary endpoint for clinical improvement as assessed by change in total symptom score. Moreover, the trial did not meet any of the secondary endpoints including mortality, time to symptom resolution, and time to return to normal activity.

In the CD12 trial, findings showed that leronlimab did not meet the primary endpoint, with no difference seen in all-cause mortality at day 28 compared with placebo (20.5% vs 21.6%, respectively). Additionally, the trial did not meet any secondary endpoints, including average length of hospitalization, which was observed to be similar between the 2 groups (21.4 days for both leronlimab and placebo treatment arms).

While the Company has publicly stated that an analysis of small subgroups from the CD12 trial did show a mortality benefit, the FDA noted in its communication that “subgroup analyses have well-established limitations, especially in the context of a clinical trial that has failed to show a benefit in the overall study population.” As such, the Agency has determined that the current data do not support the clinical benefit of leronlimab for the treatment of COVID-19.


Statement on leronlimab. [press release]. Silver Spring, MD: US Food and Drug Administration; May 17, 2021.