From left, Dr. Dimiter Dimitrov, Pitt Center for Antibody Therapeutics, Dr. John Mellors, UPMC and Pitt chief of infectious diseases, and Dr. Steven Shapiro, M.D., UPMC chief medical and scientific officer, discussing the discovery of an antibody component that has been used to construct a drug — known as Ab8 — for potential use as a therapeutic and prophylactic against SARS-CoV-2, which is the cause of COVID-19. Submitted photo

UPMC scientists have isolated the smallest biological molecule to date that completely and specifically neutralizes the SARS-CoV-2 virus, which is the cause of COVID-19.

On Tuesday, UPMC officials announced their findings during a virtual news conference with Dr. Steven Shapiro, M.D., UPMC chief medical and scientific officer; Dr. John Mellors, UPMC and Pitt chief of infectious diseases; and Dr. Dimiter Dimitrov, Pitt Center for Antibody Therapeutics.

Mellors said the antibody component, which is 10 times smaller than a full-sized antibody, has been used to construct a drug — known as Ab8 — for potential use as a therapeutic and prophylactic against SARS-CoV-2. He said Ab8 is highly effective in preventing and treating SARS-CoV-2 infection in mice and hamsters. Its tiny size not only increases its potential for diffusion in tissues to better neutralize the virus, but also makes it possible to administer the drug by alternative routes, including inhalation. Importantly, it does not bind to human cells — a good sign that it won’t have negative side-effects in people.

“There are other antibodies in development and they’re promising. Ours is special because its extremely potent,” Mellors said.

Mellors said clinical trails require FDA approval. He said hopefully the clinical trials will start at the beginning of 2021.

“Ab8 not only has potential as therapy for COVID-19, but it also could be used to keep people from getting SARS-CoV-2 infections,” Mellors said. “Antibodies of larger size have worked against other infectious diseases and have been well tolerated, giving us hope that it could be an effective treatment for patients with COVID-19 and for protection of those who have never had the infection and are not immune.”

Abound Bio, a newly formed UPMC-backed company, has licensed Ab8 for worldwide development.

Dimitrov was one of the first to discover neutralizing antibodies for the original SARS coronavirus in 2003. In the ensuing years, his team discovered potent antibodies against many other infectious diseases, including those caused by MERS-CoV, dengue, Hendra and Nipah viruses. The antibody against Hendra and Nipah viruses has been evaluated in humans and approved for clinical use on a compassionate basis in Australia.

Clinical trials are testing convalescent plasma — which contains antibodies from people who already had COVID-19–as a treatment for those battling the infection, but there isn’t enough plasma for those who might need it, and it isn’t proven to work.

UPMC officials said that’s why Dimitrov and his team set out to isolate the gene for one or more antibodies that block the SARS-CoV-2 virus, which would allow for mass production. In February, Dr. Wei Li, Pitt’s Center for Therapeutic Antibodies assistant director, began sifting through large libraries of antibody components made using human blood samples and found multiple therapeutic antibody candidates, including Ab8, in record time.

Ab8 was evaluated in conjunction with scientists from the University of North Carolina at Chapel Hill and University of Texas Medical Branch at Galveston, as well as the University of British Columbia and University of Saskatchewan.

“The COVID-19 pandemic is a global challenge facing humanity, but biomedical science and human ingenuity are likely to overcome it,” Mellors said. “We hope that the antibodies we have discovered will contribute to that triumph.”