U.K. regulator accepts Humanigen's COVID drug for speedy review, as analysts spell out reasons to be hopeful for FDA nod

After a successful data hit at the start of spring, a new chief medical officer and a jump in stock price, Humanigen is starting the summer with the U.K.'s drug regulator accepting its COVID hopeful lenzilumab for review.

Back in late March, a phase 3 test of Humanigen’s lenzilumab in hospitalized COVID-19 patients met its primary endpoint, a result it now hopes will help it gain approval in the U.K., which is being hit hard by a third wave from the delta variant, despite high vaccine uptake.

Today, the Californian biotech said the U.K.’s Medicines and Healthcare Products Regulatory Agency (MHRA) has allowed an expedited COVID-related rolling review, an extra speedy method that could see the drug on the U.K. market more quickly than the average drug. The company did not say, however, what that timeline might be.

“We are grateful this submission will receive expedited consideration by MHRA,” said Cameron Durrant, M.D., CEO of Humanigen. “The global spread of variants of concern, such as the Delta variant, highlights the continued need for proven therapies that are variant-agnostic for millions who remain at risk of COVID-19.”

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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 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 recently 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.

In the data posted in March, 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.

It also took these data to the FDA for an emergency use authorization. Before the MHRA announcement, analysts at Jefferies said in a note to clients Thursday evening that lenzilumab “is well positioned for winning an EUA approval in hospitalized Covid patients,” adding that Humanigen’s stock could move up by 60% to 80% if approved, though the downside is limited to minus 20% to 30% if a larger safety data set or additional trial are requested by the FDA.

As it was, Humanigen shares were up 15% premarket Friday morning, but quickly dropped after the market opened to be up just 1% by midday.

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.  

Analysts at Cantor have already predicted blockbuster sales, with Jefferies noting that with the delta variant hitting countries like the U.K., Israel and now the U.S., all three of which have high vaccine uptake, this means COVID may well become like flu and still require a high level of treatment outside of inoculation.