Incidence and Characteristics of Infectious Complications in Multiple Myeloma Patients Treated With Bispecific Antibodies.

Background: Bispecific antibodies (BsAbs) are a new class of immunotherapeutic agents for patients with multiple myeloma (MM). Although this new class of drug is associated with good disease control, they are also associated with increased risk of infectious complications. Since endemic community-acquired and nosocomial infections vary across the globe, we conducted this study to report real-world data of infectious complications associated with BsAbs in Korean population.

Methods: We retrospectively reviewed all MM patients who received BsAb therapy between January 2021 and January 2024 at Seoul National University Hospital. We identified 61 patients who underwent BsAb therapy at our center with median follow-up of 34 weeks (95% confidence interval, 25.85-55.85). Thirty-three patients (54%) received B-cell maturation antigen (BCMA)-targeting BsAb, and 30 (49%) received combination therapy.

Results: Of the 61 patients, 39 (64%) had at least one episode of infection. A total of 69 infections affecting patient management occurred during the study period, 3% grade 1 infection, 8% grade 2, 72% grade 3, 8% grade 4 and 8% grade 5. The most common type of infection was lower respiratory tract infection (n = 32/69, 46%), followed by systemic infection (n = 21/69, 30%). Etiology wise, viral infections were most common (67%), followed by fungal infections (13%) and bacterial infections (10%). Among viral infections, cytomegalovirus (CMV) was most common. Patients treated with BCMA-targeting BsAb or combination therapy were associated with higher incidence of CMV reactivation and clinically significant CMV infection.

Conclusion: Particular pattern of infectious complications including CMV infection was noted in Korean patients. Identifying and determining the nature of infectious disease dynamics is becoming increasingly important for optimal resource allocation and shaping healthcare policies. In this regard, our first-in-Asian population study holds its value.