The FDA stated that it could not determine if the use of lenzilumab in COVID patients outweighs the known and potential safety risks.
Shares of Humanigen have plunged nearly 60% in premarket trading after the company announced the U.S. Food and Drug Administration (FDA) rejected the company’s Emergency Use Authorization request for lenzilumab, a potential treatment for COVID-19.
In its rejection, the FDA stated that it was unable to determine if the use of lenzilumab in COVID patients outweighs the known and potential safety risks. The agency further acknowledged that it is committed to working with the company and invites it to submit additional data that could support potential EUA.
Humanigen Chief Executive Officer Cameron Durrant said in a brief announcement this morning that the company remains committed to seeing lenzilumab authorized for hospitalized COVID-19 patients. Durrant said an ongoing study conducted by the National Institutes of Health, which includes up to 500 patients, could provide the additional safety and efficacy data requested by the regulatory agency. That study, dubbed ACTIV-5/BET and which began last year, is evaluating lenzilumab in combination with Gilead Science’s Remdesivir in hospitalized coronavirus patients.
Lenzilumab has been assessed as a potential treatment for the hyper-immune response seen in some COVID-19 patients known as the cytokine storm. The cytokine storm occurs when a large amount of inflammatory cytokines are produced by the body at an exceedingly high rate, which can ultimately attack healthy tissue and organs. Prior to the pandemic, Humanigen had been assessing lenzilumab as a treatment for cancer patients who receive CAR-T cell therapies, as cytokine storm is one of the potential side effects of that treatment. Earlier this year, the company posted positive results of lenzilumab in patients treated with CAR-T in diffuse large B-cell lymphoma.
Data supporting the company’s EUA showed that clinical trial patients treated with lenzilumab saw a 54% improvement in the likelihood of survival without ventilation (SWOV) in newly hospitalized patients. Additionally, lenzilumab improved the “relative likelihood” of SWOV by 92% in patients who were also treated with corticosteroids and Gilead Sciences’s remdesivir, an approved antiviral for the SARS-CoV-2 virus.
When Humanigen submitted its EUA application to the FDA during the Phase III study, there had been no serious adverse events attributed to lenzilumab, and the overall safety profile was comparable to placebo.
Lenzilumab is an anti-human granulocyte macrophage-colony stimulating factor (GM-CSF) monoclonal antibody designed to prevent and treat an immune hyper-response called “cytokine storm” associated with the coronavirus. GM-CSF is a cytokine that has been linked to poor outcomes in COVID-19 patients. Hospitalized cases have proven to be challenging to treat, with several drugs failing in clinical studies.
While the FDA stymied Humanigen, the company is also seeking Marketing Authorization for lenzilumab in the United Kingdom.
Humanigen, previously known as KaloBios, had ramped up its manufacturing capabilities ahead of potential EUA.
