Impact of COVID-19 monoclonal antibodies on outcomes of COVID-19 infection in hematopoietic stem cell transplant and chimeric antigen receptor therapy recipients.

Background: Hematopoietic stem cell transplant (HSCT) and chimeric antigen receptor T-cell therapy (CAR-T) recipients are at higher risk of serious complications of COVID-19 infection than the general population. Though there is evidence that monoclonal antibodies (MCA) against COVID-19 reduce the risk of death and hospitalization in the general population, data regarding their efficacy in HSCT and CAR-T recipients remains scarce.

Methods: We conducted a retrospective review of HSCT and CAR-T recipients to compare 30-day outcomes between patients who did and did not receive MCA after their first episode of COVID-19 between May 1, 2020 and December 31, 2022. Outcomes were defined as the most severe complication experienced out of the following: 30-day emergency department visit, hospitalization, intensive care unit admission, and death after COVID-19 infection.

Results: We identified 166 patients comprised of 53.6% allogeneic HSCT, 35.5% autologous HSCT, and 10.8% CAR-T recipients; 107 had received a COVID-19 vaccine >2 weeks prior to testing positive, and 40 were treated with MCA. After adjusting for age, presence of symptoms at the initial positive test, and COVID-19 vaccination status, patients who did not receive MCA were five times more likely to develop complications after COVID-19 infection (adjusted odds ratio 5.0 [95% CI, 1.9-12.8], p = .001).

Conclusion: HSCT and CAR-T recipients who received MCA following COVID-19 infection were far less likely to develop COVID-related complications than those who did not receive MCA, regardless of vaccination status. This underscores the potential benefit of developing novel MCA with efficacy against circulating COVID-19 strains.