The US Food and Drug Administration (FDA) has provided written guidance for Humanigen to submit an application seeking emergency use authorisation (EUA) to treat Covid-19 using the company’s drug candidate lenzilumab.

After a Type B meeting, FDA said that Humanigen’s intended filing may be sufficient for an EUA request, subject to Phase III clinical trial results. The agency also offered guidance and support for a biologics licence application and approval pathway.

Lenzilumab is a monoclonal antibody designed to neutralise granulocyte-macrophage colony-stimulating factor (GM-CSF). It is intended to prevent or mitigate some serious side-effects caused by CAR-T therapy.

The company is now testing the drug’s potential in preventing or reducing the cytokine release syndrome that could lead to severe lung dysfunction and acute respiratory distress syndrome (ARDS) in serious Covid-19 cases.

Humanigen CEO Cameron Durrant said: “FDA was very helpful and provided clear guidance on our EUA submission plan. We are encouraged by our Type B meeting and remain confident in our programme and preparedness plans in advance of a potential EUA.”

Currently, a randomised, placebo-controlled, double-blinded Phase III registration study of lenzilumab is recruiting participants in the US and Brazil.

The study has 29 approved sites and 24 are actively enrolling hospitalised adults with Covid-19 who need supplemental oxygen and are at high disease progression risk.

In the US, 17 sites are active and recruiting subjects across cities with high rates of confirmed infection. Of the 12 approved sites in Brazil, seven are validated to commence enrolment.

Multiple patients have been treated at four sites in Brazil, which recorded more than 4.8 million cases and 143,000 deaths so far.

Humanigen has secured approval from regulatory agency COFEPRIS to expand the trial to Mexico. Trial sites are being activated in the country to begin patient enrolment.

Top-line results from the study are expected in the fourth quarter of this year.