Humanigen links drug to improvements in severe COVID-19 patients

Humanigen has estimated its anti-GM-CSF antibody caused 37% more recoveries than standard of care in hospitalized COVID-19 patients. The data remain blinded, but Humanigen calculated the effect of the drug based on the changes to enrollment requested by the data safety monitoring board (DSMB).

The phase 3 trial has an adaptive design that only permits the continued enrollment of patients if the interim analysis shows an average improvement in recoveries of 29% or more. The monitoring board looked at the data for the interim analysis and recommended raising the target number of recoveries from 257 to 402.  

By working back from that recommendation, Humanigen has estimated the phase 3 data show a 37% improvement in recoveries in the cohort of patients who received its lenzilumab. Humanigen is yet to see the data but reverse-engineered the board’s recommendation to calculate the headline finding. 

Dale Chappell, chief scientific officer at Humanigen, talked up the implications of the board’s advice.

“Based on this feedback from the DSMB, we believe the phase 3 trial is significantly de-risked. Targeting 402 events improves the probability of success, maintains the power of the study at 90% and further supports our plans for emergency use authorization and biologics license application submission,” Chappell said in a statement. 

To achieve the 402 events recommended by the board, Humanigen plans to increase enrollment to around 515 patients. The original trial design had a target enrollment of 300 patients. To recruit the extra subjects quickly, Humanigen plans to activate additional trial sites. The next interim analysis will happen after 302 events, which Humanigen calculated will require around 390 patients.

Humanigen disclosed the outcome of the interim analysis at the same time it shared news about an agreement with the Department of Defense to support the development of lenzilumab. Humanigen framed the agreement as a positive for its efforts to complete the phase 3 and bring lenzilumab to market.

If the trial succeeds, lenzilumab could emerge as part of the arsenal for treating some of the sickest COVID-19 patients. Lenzilumab may stop cytokine storms, the severe hyperimmune responses that drive organ damage in some COVID-19 patients. Currently, physicians treat such severe patients with steroids and Gilead’s remdesivir, but there remains a need for more efficacious therapies. 

The chances of anti-SARS-CoV-2 antibodies meeting that need have diminished in recent weeks as prospects in development at Eli Lilly and Regeneron have failed in severe COVID-19 patients. Efforts to use existing drugs, notably anti-IL-6 antibodies such as Sanofi’s Kevzara, to stop cytokine storms in COVID-19 patients have also failed.