ROCHESTER, Minn. — New research from Mayo Clinic has shown that monoclonal antibody therapies for COVID-19 are safe and effective in a population that arguably needs them the most: those who have less protection from vaccination and who are at increased risk of poor outcomes from COVID-19 due to having received solid organ transplantation in their past.

The study, published Thursday, June 10, in the journal Open Forum Infectious Disease describes the care of 73 solid organ transplant recipients patients given either the monoclonal antibody bamlanivimab made by Eli Lilly, or casirivimab-imdevimab combination marketed by Regeneron.

"Monoclonal antibody therapy is really important for the transplant population because they are less likely to develop their own immunity," Mayo Clinic infectious diseases specialist and senior author Dr. Raymund Razonable said in a statement.

Among the study's findings, though transplant recipients historically have elevated risk of poor outcomes with COVID-19, none of the patients treated died, required mechanical ventilation or experienced organ rejection. Only one of the patients needed to be admitted to the ICU.

Monoclonal antibody therapy for COVID-19 is one of a handful of treatments whose efficacy against the virus is well-established. The treatments are lab-engineered proteins designed to mimic natural antibodies targeting the spike proteins on SARS-CoV2.

Newsletter signup for email alerts

Since being given an Emergency Use Authorization in November 2020, the infusions are used for newly diagnosed COVID-19 patients with elevated risk factors for poor outcomes.

Early treatment is critical, however, with patients receiving the infusions at dedicated COVID-19 monoclonal antibody treatment centers.

With the success of vaccination in reducing new case counts to levels not seen since the start of the pandemic, monoclonal antibody therapy for COVID-19 is increasingly of interest to those who cannot produce the needed antibodies in response to vaccination.

Research shows organ transplant recipients, who take anti-rejection drugs that inhibit their immune response, have only a 65% likelihood of developing immunity following COVID-19 vaccination, compared to 95% effectiveness for others.

"Vaccination is an option for immunocompromised, but they might not respond as well," Razonable said. "If they develop COVID-19 we (now) know this is going to be an option for them."

Further clouding the picture, concerns had existed that giving transplant recipients a therapy that initiates an immune response could increase the risk of organ rejection, as their body fights the donor organ along with spike protein.

"One of the concerns was that this is an antibody that promotes rejection," Razonable said. "While that was of concern, we did not see that."

Because organ recipients were not included in the studies that helped the therapies gain approval, it was not known if they could safely take the therapies. Researchers charted the outcomes in recipients of kidneys, livers, lungs, hearts and pancreas.

The patients had been five years out from the date of their transplant on average. All infusions were given at dedicated COVID-19 monoclonal antibody transfusion centers operated by Mayo Clinic.

The study was limited in that it was an observational case review which did not study a control population of transplant recipients who did not receive the therapies. Future research will look at the effectiveness of COVID-19 monoclonal antibody therapy in other immunocompromised populations, Razonable said.