Prospective Randomized Phase II Study Evaluating Efficacy and Safety of IgPro20 as Infection Prophylaxis in Patients With Multiple Myeloma and Hypogammaglobulinemia Receiving Therapy With a Bispecific Monoclonal Antibody (BsAbs)

Inclusion Criteria: * Diagnosis of RRMM receiving a commercially available bispecific antibody * Received at least 1 but no more than 4 cycles of BsAb * Males or females greater than or equal to 18 years old at the time of consent * ECOG ≤ 3 * Life expectancy \> 12 months Exclusion Criteria: * HSCT within 3 months before enrollment * Planned CAR-T therapy in the next 6 months * \>1 major (deep-seated) infection within the preceding 3 months * HIV infection, Active HCV, or Active HBV infection * Pregnancy * Neutrophils \< 500 x 10\^3 per mL, Platelets \< 30 x 10\^9 per mL * History of cancer…