Polyclonal antibody treatment for COVID-19 moves to phase 3 trial at UT Southwestern

Researchers at the University of Texas Southwestern Medical Center are studying a polyclonal antibody therapy to treat nonhospitalized people with early COVID-19 as part of a national effort to keep patients with the virus out of the hospital.

The polyclonal antibody treatment, called SAB-185, is the first of its kind in the ACTIV-2 Outpatient Monoclonal Antibodies and Other Therapies Trial, which is led by the AIDS Clinical Trial Group and sponsored by the National Institute of Allergy and Infectious Diseases.

UT Southwestern is one of several universities and companies across the country participating in the trial.

SAB-185, created by Sioux Falls, South Dakota-based SAB Biotherapeutics, contains several different COVID-19 antibodies that are generated by cows that have been genetically engineered to make human antibodies. Once the cows generate those antibodies, samples of their blood are collected and the antibodies are separated and purified. The treatment is administered through a single IV infusion.

Polyclonal antibodies attack several parts of the coronavirus, unlike monoclonal antibody treatments that just attach to the virus’ spike protein, said Dr. Mamta Jain, UT Southwestern professor of internal medicine. This could make the treatment more versatile against new variants.

“The health care system is overwhelmed, and I think that, if we can find something that can be administered as an outpatient and keep people out of the hospital, that’s important,” she said.

UT Southwestern is also studying Synairgen’s interferon beta therapy, an inhaled antiviral protein, through the ACTIV-2 trial.

Treatments that keep the people most at-risk for hospitalization with COVID-19 — those who are unvaccinated or have pre-existing conditions — are particularly important as the omicron variant continues to spread across the U.S., Jain said.

Preliminary data out of South Africa show omicron appears to cause less severe disease than previous versions of COVID-19 but that it seems to be more easily transmitted. The strain is now the dominant variant in the U.S., just over a month after it was first identified in South Africa.

Hospitalizations related to COVID-19 are climbing in Dallas-Fort Worth, with coronavirus patients making up nearly 17% of hospital bed capacity in the North Texas trauma service area on Monday, according to data from the Dallas-Fort Worth Hospital Council.

Monoclonal antibody treatments, like one made by Regeneron, have been used for months to treat patients who aren’t hospitalized or severely ill from COVID-19 yet, although their effectiveness against new variants is still being tested.

German researchers recently found that COVID-19 therapies developed by Eli Lilly and Regeneron lose most of their effectiveness when exposed to the omicron variant in laboratory tests. Separate researchers found that GlaxoSmithKline’s and Vir’s antibody treatments still held up against the new variant.

Scientists are racing for new treatment options, a fact that was taken into consideration in the ACTIV-2 trial’s design. Its randomized and adaptive platform of phase 2 and phase 3 studies allows promising therapies to be added or removed over the course of the trial to test a variety of new agents.

SAB-185 is now in a phase 3 study where it will be compared against Regeneron’s monoclonal antibody treatment, which can be administered through either IV infusion or injection. Participants will be randomized to receive either the SAB-185 or Regeneron’s therapy, which contains two monoclonal antibodies.

SAB Biotherapeutics announced Thursday that SAB-185 retains neutralization activity against the omicron variant in an in vitro pseudovirus model, according to data generated by scientists at the FDA Center for Biologics Evaluation and Research.

To qualify for the ACTIV-2 trial, participants must have tested positive for COVID-19 in an outpatient setting within 10 days and started experiencing symptoms within eight days of enrolling.

“People living in North Texas who have recently been diagnosed with COVID-19 and are not hospitalized have the opportunity to make a huge contribution by participating in this study,” Jain said.

Those interested in participating in the study at UT Southwestern can email idcru@utsouthwestern.edu or call 214-645-9390.