Flat dose intravenous immunoglobulin primary infection prophylaxis in multiple myeloma patients on BCMA and GPRC5D bispecific antibody therapy: the Vanderbilt experience

Bispecific antibodies (BsAbs) can cause profound hypogammaglobulinemia. Conventional infection prophylaxis has utilized weight-based IVIG dosing. However, the use of flat IVIG dosing can significantly reduce IVIG utilization. We evaluated hypogammaglobulinemia and infection risk in relapsed/refractory multiple myeloma (RRMM) patients treated with BsAbs who received flat-dose IVIG for primary infection prophylaxis. Among thirty patients, 73% had ≥1 and 43% had ≥2 infectious episodes. By severity, 27% of infections were CTCAE v5 grade three or higher and there were 2 sepsis-related deaths. Overall, flat-dose IVIG demonstrates feasibility for primary infection prophylaxis in RRMM patients receiving BsAbs.