Humanigen's COVID-19 phase 3 hits goal, sending stock soaring

Getty Images/Naeblys
Shares in Humanigen jumped 64% in premarket trading. (Getty Images/Naeblys)

A phase 3 clinical trial of Humanigen’s lenzilumab in hospitalized COVID-19 patients has met its primary endpoint. Humanigen plans to use the data to seek emergency use authorization from the FDA. 

Lenzilumab targets GM-CSF, a cytokine associated with negative outcomes in COVID-19 patients. By neutralizing the cytokine, drug developers including Humanigen and GlaxoSmithKline have predicted that they may be able to counter life-threatening complications that arise when the immune system reacts particularly strongly to the virus. 

To test the hypothesis, investigators randomized 520 hospitalized COVID-19 patients to receive an infusion of lenzilumab or placebo on top of standard-of-care treatments such as dexamethasone and Gilead Sciences' Veklury.

After 28 days, the rate of ventilator-free survival was higher in the lenzilumab arm, causing the trial to hit its primary endpoint with a p-value of 0.0365. Humanigen changed the primary endpoint twice in the months after initiating the phase 3 trial in April 2020.  

In the treatment group, the Kaplan-Meier estimate for invasive mechanical ventilation and/or death was 15.6%, compared to 22.1% in the placebo group. Humanigen also reported a “favorable trend” in the mortality rate, which was 9.6% in the lenzilumab arm and 13.9% in the placebo group. Analysts at Cantor said the "homerun" data "could translate to blockbuster sales in COVID-19 this year."

With investigators seeing no new serious adverse events, Humanigen thinks it has the data to seek emergency approval from the FDA. Humanigen CEO Cameron Durrant, M.D., said the company will file with the FDA “as soon as possible” and share the data with “other authorities worldwide.”

If approved, lenzilumab could serve a set of hospitalized patients who have proven difficult to treat with other COVID-19 drugs. Anti-SARS-CoV-2 antibodies have struggled in the population, potentially because in hospitalized COVID-19 patients the immune response is as much of a factor as the virus itself. Researchers have tested other drugs designed to tamp down immune responses, including Roche’s Actemra and Sanofi’s Kevzara, with mixed results.   

Shares in Humanigen jumped 64% in premarket trading. The surge continues the turnaround in the fortunes of Humanigen, which was trading for less than $2 a share early in 2020. Today, Humanigen is trading above $20 a share.