SAB Biotherapeutics has reported that the US National Institutes of Health (NIH) is halting subject enrolment in the Phase III Covid-19 trial of SAB-185 under the ACTIV-2 Program.

SAB-185 was being analysed as part of the Phase III ACTIV-2 master protocol studying therapies for Covid-19 in people with mild-moderate disease who are at increased risk for progression to hospital admission.

It is a fully-human, specifically targeted, broadly neutralising polyclonal antibody treatment candidate.

SAB attributed the termination of enrolment by NIH to low Omicron-linked Covid-19 hospital admission and mortality rates that made the existing trial design unfeasible statistically.

The decline in hospital admission and mortality rates were the primary endpoints of the Phase III trial.

On meeting the preliminary pre-specified efficacy and safety criteria, SAB-185 was progressed into the Phase III trial. But the independent Data and Safety Monitoring Board (DSMB) advised terminating the trial due to “operational futility.”

Reduced hospitalisation and mortality rates reported lately in the trial prompted the sponsors to conclude that despite the possible efficacy of SAB 185 it would be impossible to show statistically significant clinical efficacy with the current study design.

SAB Biotherapeutics co-founder, president and CEO Eddie Sullivan said: “Our team continuously monitors the evolving pandemic to plan for the further development of SAB-185, focusing on identifying Covid-19 patient groups who could potentially benefit from SAB-185, including the potential for prophylactic or therapeutic use in targeted high-risk populations and in those who will become ill from newly emerging variants, along with the potential development of an injectable formulation. 

“We look forward to analysing data from the ACTIV-2 trial to help inform our future clinical initiatives when it becomes available.”

In October last year, the company dosed the first subject in the Phase III ACTIV-2 trial of SAB-185 to treat Covid-19.