Plot Twists for ‘Mabs’ as COVID-19 Treatment

Where the monoclonal antibody treatments will fit into the day-to-day reality of the COVID-19 pandemic is difficult to say. In early January, it became apparent that a relatively small proportion — some press reports put it at 30% — of the available doses were actually being used. One of the main reason is that the “mabs” need to be administered relatively early on in the course of a case of COVID-19. Delays in getting test results or a prescription for one of the monoclonal antibody treatments — or both — can put people outside the window when the treatments will be effective. The fact that the monoclonal antibodies are administered intravenously is another impediment to their use.

Those practical problems stand in sharp relief to a spurt of encouraging results from clinical trials. The monoclonal antibodies are living up their billing as perhaps the most effective COVID-19 treatment. There are, though, som some twists to the storyline.

Take for example the results of a study funded by Eli Lilly published online in JAMA on January 21. They showed that a combination of a pair of Lilly’s monoclonal antibodies, bamlanivimab and etesevimab, reduced the SARS-CoV-2 viral load of people with mild-to-moderate cases of COVID-19. But viral loads did not decrease when patients took the bamlanivimab alone.

Results reported the same week in the New England Journal of Medicine suggested that a middle-level dose of bamlanivimab may be the most effective and that, regardless of the dose, the monoclonal antibody treatment reduced hospitalizations. Meanwhile, Lilly put out a press release trumpeting results that showed that bamlanivimab prevented COVID-19 infections among the staff and residents of nursing homes and assisted-living facilities. Lilly said it will have the study published in a peer-reviewed journal. If the results hold up, bamlanivimab could wind up wearing a second hat as COVID-19 prophylaxis.