The Pfizer/BioNTech BNT162b2 vaccine has been approved for the prevention of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and is recommended for immunosuppressed patients.

However, its efficacy and safety in patients undergoing immunologic cell therapy have not been well-documented.

In this study, presented at EHA 2021, the researchers evaluated the efficacy and safety of the BNT162b2 vaccine in patients that underwent haematopoietic cell transplantation (HCT) and chimeric antigen receptor (CAR)-T therapy.

They prospectively followed 79 vaccinated patients who were actively treated at the Tel Aviv Sourasky Medical Center and monitored the safety profile and the humoural immune response to the vaccine.

Overall, the vaccine was well-tolerated and all adverse events resolved within a few days except for one secondary graft rejection, which is still under investigation.

They observed that only 36% of patients who received CAR-T therapy developed a humoural antibody response compared with 81% of patients who underwent allogeneic HCT.

In addition, patients with B cell aplasia and those who received the vaccine shortly after infusion of cells were less likely to develop antibodies.

Taken together, these data demonstrate that the humoural response to the BNT162b2 vaccine is significantly impaired in patients receiving CAR-T, as opposed to those after allogeneic HCT who had a good response.

Source: European Hematology Association (EHA)