Shares of Humanigen (OTC:HGEN), which were up 863% year to date through Monday's close, continued their upward momentum Tuesday after one of its monoclonal antibody drugs got an endorsement from scientists at the National Institutes of Health (NIH). The National Institute of Allergy and Infectious Diseases (NIAID), which is part of the NIH, plans to test Humanigen's lenzilumab in a clinical trial for hospitalized patients with COVID-19.

NIAID's study, dubbed the Big Effect Trial (BET), is testing multiple drugs to find the best combination to help COVID-19 patients. It will test lenzilumab in combination with Gilead Sciences' antiviral remdesivir in 100 patients, compared to 100 patients who will receive remdesivir alone. NIAID plans to take an interim peek at the data after half of the patients have been enrolled.

Lenzilumab works by blocking a protein called granulocyte macrophage-colony stimulating factor (GM-CSF), which is secreted by immune cells to tell the body to make more immune cells. With a typical infection, GM-CSF's positive feedback loop helps the body fight off the disease more quickly, but in patients with moderate-to-severe COVID-19, the immune system overreacts, causing many of the most dangerous symptoms. Researchers hope that blocking GM-CSF with Lenzilumab will rein in the autoimmune inflammation and reduce organ damage.

Doctor in protective equipment talking to a patient with a mask

Image source: Getty Images.

In addition to the BET study, Humanigen is in the midst of a phase 3 study that compares lenzilumab plus standard of care to standard of care alone in approximately 238 coronavirus patients.

Initial data from an earlier study of 12 COVID-19 patients showed patients treated with lenzilumab recovered in a median of five days. While that's substantially faster than the 10-to 11-day recovery times found in studies of patients taking remdesivir, investors should keep in mind that cross-trial comparisons are difficult, especially when a drug trial arm has so few patients in it.