US NIH stops ACTIV-2 phase 3 trial of Covid-19 drug candidate SAB-185

SAB Biotherapeutics said that the US National Institutes of Health (NIH) is discontinuing the phase 3 ACTIV-2 trial of the company’s SAB-185 for the treatment of Covid-19 because of low hospitalization and death rates in the trial.

The National Institutes of Health is therefore stopping enrollment in its Covid-19 phase 3 trial, said the US-based clinical-stage biopharma company.

SAB-185 was being studied as part of the ACTIV-2 master protocol assessing treatments for Covid-19 in patients having mild-moderate infections, who are highly prone for progression to hospitalization.

Eddie J. Sullivan — co-founder, President, and CEO of SAB Biotherapeutics said: “The NIH-sponsored ACTIV-2 Phase 3 master protocol was designed when previous COVID-19 variants resulted in high infection and hospitalization rates.

“The good news is that infections and hospitalizations are now falling sharply in the US. But this decrease also has had the effect of making the current ACTIV-2 Phase 3 study design statistically unworkable, and the NIH has therefore decided to stop patient enrollment.”

US NIH stops ACTIV-2 phase 3 trial of SAB Biotherapeutics’ Covid-19 drug candidate SAB-185

US NIH stops ACTIV-2 phase 3 trial of SAB Biotherapeutics’ Covid-19 drug candidate SAB-185. Photo courtesy of Duane Lempke/

According to SAB Biotherapeutics, decreases in hospitalization and death rates were the primary endpoints of the phase 3 trial. However, the low rates of hospitalization and death observed recently in the study have driven the sponsors to conclude that, notwithstanding SAB 185’s potential efficacy, it will not be possible to prove statistically significant clinical efficacy with the existing design of the study as very few of the enrolled patients with Covid-19 had an observable study endpoint event such as hospitalization.

SAB-185 had in the past achieved the initial pre-specified safety and efficacy criteria to continue to the next phase of the ACTIV-2 phase 3 trial, but the independent data and safety monitoring board (DSMB) recommended that the study be discontinued for reasons of “operational futility”.

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