Humanigen has reported initial topline results showing that its lenzilumab in combination with remdesivir failed to achieve statistical significance on the primary endpoint of the National Institute of Allergy and Infectious Diseases’ (NIAID) ACTIV-5/BET-B clinical trial in hospitalised Covid-19 patients.

An investigational antibody, lenzilumab attaches to and neutralises granulocyte-macrophage colony-stimulating factor (GM-CSF). 

ACTIV is a US National Institutes of Health (NIH) directed public-private partnership for developing a coordinated research approach to prioritise and expedite the development of promising therapies and vaccines. 

A series of double-blind, placebo-controlled, randomised trials, ACTIV-5 (Big Effect Trial, BET) utilises common analyses and endpoints to assess if certain approved or investigational treatments could potentially treat hospitalised Covid-19 patients.

In the study, lenzilumab in combination with remdesivir was analysed against placebo plus remdesivir in Covid-19 patients admitted to the hospital.

According to the results, the trial did not attain statistical significance on the primary endpoint of the proportion of subjects with baseline CRP<150 mg/L and aged below 85 years, alive and without needing mechanical ventilation through day 29. 

Furthermore, a non-significant trend toward a decline in mortality in the overall subject population was reported. 

In the ACTIV-5/BET-B study, no new safety signals linked to lenzilumab were observed.

Humanigen chairman and CEO Cameron Durrant said: “We are grateful for the constructive collaboration with NIH/NIAID; while the ACTIV-5/BET-B study showed signs of a clinical effect, the benefit demonstrated was not able to confirm the positive results we saw in our Phase III LIVE-AIR study. 

“In order to prove the therapeutic benefits of immunomodulators, platform studies comprising thousands of patients have been necessary. 

“With the continued resurgence of Covid-19, further exploration of variant agnostic treatments to improve outcomes in hospitalised Covid-19 patients should be a priority.”

In January this year, the company concluded target enrolment in Phase II/III ACTIV-5/BET-B trial of lenzilumab.