ACTIV-3 clinical trial evaluating investigational COVID-19 therapies closes enrollment in two sub-studies

Reviewed by Emily Henderson, B.Sc.Mar 5 2021

The ACTIV-3 clinical trial, which is evaluating the safety and efficacy of investigational therapeutics for COVID-19 in hospitalized patients, has closed enrollment in two sub-studies: one examining the investigational monoclonal antibody therapy VIR-7831, and another evaluating the investigational combination monoclonal antibody therapy containing BRII-196 and BRII-198.

The sub-studies were halted by the trial sponsor, the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, on March 1, 2021, following an interim review and recommendation from the independent Data and Safety Monitoring Board (DSMB).

The DSMB analysis determined that the Brii therapeutic did not meet the inclusion criteria for further enrollment in the trial, due to futility. The initial analysis of data from the VIR-7831 sub-study indicated that the investigational treatment met the pre-specified criteria for study continuation. However, participants entering the control group had more advanced illness overall than those enrolling in the group receiving the therapeutic, so the data were adjusted to account for this imbalance. Once this difference was taken into account, the DSMB recommended that recruitment in the VIR-7831 sub-study should cease, due to futility.

There were no safety concerns with either therapeutic agent, and no indication of harm in the therapeutic arms compared to the placebo arm.

VIR-7831 was developed through a partnership between GlaxoSmithKline (Brentford, United Kingdom) and Vir Biotechnology, Inc. (San Francisco). BRII-196 and BRII-198 are manufactured by Brii Biosciences (Durham, N.C. and Beijing).

ACTIV-3, part of the Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) public-private partnership, is a master protocol designed to allow for the study of multiple investigational agents compared to placebo in adults hospitalized with COVID-19. All trial participants receive Veklury (remdesivir), a drug approved by the Food and Drug Administration for the treatment of COVID-19 in hospitalized patients.

The trial is divided into sub-studies, each of which evaluates a different candidate therapeutic. After five days, the clinical status of the participants is assessed using two seven-point ordinal scales. Each scale ranges from being able to undertake usual activities with minimal or no symptoms, to death. After approximately 150 participants are enrolled in each sub-study and 150 enrolled in the corresponding placebo group, the DSMB conducts a pre-planned interim safety and efficacy review to determine if the sub-study should be expanded to enroll additional participants or if it should be closed.

The DSMB reviewed data on 344 people in the VIR-7831 sub-study and 343 people in the Brii-196 and Brii-198 combination sub-study. Volunteers in both sub-studies will continue to be followed for 18 months. Currently, NIAID and trial coordinating investigators are analyzing the data, and they will provide more information in a forthcoming report.

Participants continue to be enrolled in the ACTIV-3 sub-study evaluating AZD7442, an investigational long-acting antibody combination developed by biopharmaceutical company AstraZeneca (Cambridge, United Kingdom). The DSMB will review the safety and efficacy of this sub-study once approximately 300 participants have been enrolled.

The NIAID-supported ACTIV-2 trial will continue to test the BRII-196 and BRII-198 combination monoclonal antibody therapeutic regimen in people with mild-to-moderate COVID-19 who have not required hospitalization. It is being overseen by the same DSMB that oversees ACTIV-3, and the DSMB does not recommend any changes to ACTIV-2 at this time.