Roivant Sciences has dosed the first participant in the BREATHE clinical trial of monoclonal antibody gimsilumab to treat Covid-19 patients with lung injury or acute respiratory distress syndrome (ARDS).

Dosing occurred at Temple University Hospital, Philadelphia, and will be immediately commenced at other sites.

Gimsilumab is a fully human monoclonal antibody that acts on granulocyte-macrophage colony-stimulating factor (GM-CSF).

Roivant evaluated the drug in various non-clinical studies and two clinical studies, including a four-week Phase I study in healthy volunteers.

Data revealed a favourable safety and tolerability profile.

The new adaptive, randomised, double-blind, placebo-controlled, multi-centre trial will assess the effect of the drug’s intravenous (IV) formulation on mortality in Covid-19 patients.

It is designed to recruit up to 270 patients with confirmed Covid-19 and clinical evidence of acute lung injury or ARDS. Participants will receive gimsilumab or placebo.

The primary endpoint is incidence of mortality by day 43, while key secondary endpoints include the incidence and duration of mechanical ventilation use, number of ICU days and inpatient hospitalisation days.

Harvard Medical School medicine professor Dr Mandeep Mehra said: “GM-CSF-targeted immunomodulation to address the aberrant host immune response in Covid-19 appears promising for reducing lung injury and death in this aggressive illness.

“The rapid initiation of this pivotal trial with gimsilumab is impressive given the pressing need for effective therapies that reduce the morbidity encountered with Covid-19.”

Some hospitalised Covid-19 patients have an overactive immune response that involves cytokine dysregulation and elevated inflammatory myeloid cells that cause lung injury, ARDS and death.

GM-CSF is thought to be involved in lung hyper-inflammation and upstream operation of other pro-inflammatory cytokines and chemokines.