Molecular Partners Announces First Patient Dosed in COVID-19 NIH-Sponsored ACTIV-3 Trial Evaluating Antiviral Candidate Ensovibep

Zurich-Schlieren, Switzerland, June 13, 2021. Molecular Partners AG (SIX: MOLN), a clinical-stage biotech company developing a new class of custom-built protein drugs known as DARPin® therapeutics, today announced that the first patient has been dosed in a new Phase 3 sub-study evaluating ensovibep, as part of the National Institutes of Health’s (NIH) Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) public-private partnership designed to speed development of treatments and vaccine candidates for COVID-19. Molecular Partners also announced that the U.S. Food and Drug Administration (FDA) has granted ensovibep Fast Track designation, which is intended to expedite the development and review of new therapies to treat serious conditions and fill an unmet medical need.
As part of the ACTIV-3 international master protocol, the new Phase 3 sub-study is designed to evaluate the safety and efficacy of ensovibep for the treatment of COVID-19 positive adults in the hospitalized setting. Ensovibep is an anti-SARS-CoV-2 investigational DARPin® therapeutic candidate designed to bind the virus’ spike protein on three distinct sites simultaneously to inhibit viral entry into cells and proliferation of the virus. In order to be selected for ACTIV-3, Molecular Partners provided the NIH with relevant data and in addition provided ensovibep for independent preclinical assessments by the NIH.

Initial results from a Phase 1 trial evaluating ensovibep in healthy volunteers were announced in March 2021, indicating that ensovibep was well tolerated with a half-life in the range of 2-3 weeks. These promising results have informed the decision to move forward with the EMPATHY clinical trial program, which initiated enrollment in May 2021, and is being conducted by Novartis, with Molecular Partners as sponsor. The EMPATHY trial is a Phase 2 and 3 study that will seek to enroll 2,100 patients with COVID-19 in the ambulatory setting, to evaluate the safety and efficacy of ensovibep in preventing worsening symptoms and hospitalizations.

ACTIV-3 Clinical Trial Design

As previously described, the ACTIV-3 trial arm evaluating ensovibep is planned to initially enroll 300 participants who have been hospitalized with mild to moderate COVID-19 with fewer than 13 days of symptoms, who will receive either ensovibep or placebo. Participants will also receive standard of care for COVID-19, including the FDA-approved antiviral remdesivir. Five days after dosing, participants’ clinical status will be assessed, based on need for supplemental oxygen, mechanical ventilation, or other supportive care. The protocol includes an interim analysis for futility after the first 300 patients have been randomized and recruited. If the ensovibep treatment arm appears to have a positive benefit:risk profile, the trial will enroll an additional 700 participants. Trial participants will be followed for 90 days following enrollment to analyze their response to treatment. The primary efficacy endpoint is the time from randomization to participants’ sustained recovery for 14 days after release from the hospital.


On April 17, 2020 the National Institutes of Health (NIH) announced the Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) public-private partnership to develop a coordinated research strategy for prioritizing and speeding development of the most promising treatments and vaccines.

Coordinated by the Foundation for the National Institutes of Health (FNIH), ACTIV brings NIH together with its sibling agencies in the Department of Health and Human Services, including the Biomedical Advanced Research and Development Authority (BARDA), Centers for Disease Control and Prevention (CDC), and the U.S. Food and Drug Administration (FDA); other government agencies including the Department of Defense (DOD) and Department of Veterans Affairs (VA); The Operation (formerly known as Operation Warp Speed); the European Medicines Agency (EMA); and representatives from academia, philanthropic organizations, and numerous biopharmaceutical companies.

Media release