Chimeric antigen receptor (CAR) T cell therapies have dramatically improved treatment outcomes for patients with relapsed or refractory B-cell acute lymphoblastic leukemia, large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, and multiple myeloma. Despite unprecedented efficacy, treatment with CAR T cell therapies can cause a multitude of adverse effects which require monitoring and management at specialized centers and contribute to morbidity and non-relapse mortality. Such toxicities include cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, neurotoxicity distinct from ICANS, immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome, and immune effector cell-associated hematotoxicity that can lead to prolonged cytopenias and infectious complications. This review will discuss the current understanding of the underlying pathophysiologic mechanisms and provide guidelines for the grading and management of such toxicities.

There are significant disparities with regards to incidence, timely diagnosis, access to treatment, clinical trial participation and health care utilization that negatively impact outcomes for African American patients with multiple myeloma. Health care providers have a role in ameliorating these disparities with thoughtful consideration of historical, sociocultural, individual and disease characteristics that influence the care provided to African American patient population. This review by a group of experts committed to health disparity in multiple myeloma provides a snapshot of disparities at both biologic and non-biologic levels, barriers to clinical care, and best practices to ensure that African American patients receive the best care available.

Ciltacabtagene autoleucel (cilta-cel) and idecabtagene vicleucel (ide-cel), 2 B-cell maturation antigen (BCMA)–directed chimeric antigen receptor T-cell (CAR-T) therapies, have transformed outcomes for relapsed/refractory multiple myeloma; however, the 6 to 8 weeks manufacturing time risks disease progression or death in up to 10% of patients. Talquetamab, a G-protein–coupled receptor, family C, group 5, member D (GPRC5D)–targeting bispecific antibody, represents a promising option. We performed a multi-institutional retrospective analysis across 20 centers (18 United States, 2 Germany) evaluating talquetamab as a bridging therapy prior to cilta-cel or ide-cel. Among 134 patients receiving talquetamab, 119 proceeded to CAR-T (n = 98 cilta-cel, n = 21 ide-cel). Reasons for not proceeding (n = 15) included progression (n = 7), manufacturing failure (n = 6), or patient decision (n = 2). Median age was 65 years and had median 5 prior lines of therapy. Notably, 85% would not have met CARTITUDE-1/KarMMa eligibility criteria. Talquetamab was administered for a median 23 days. Toxicity was manageable: no grade ≥3 cytokine release syndrome (CRS), 2% grade 3 immune effector cell–associated neurotoxicity syndrome (ICANS) and grade 1 to 2 talquetamab unique toxicities (70% oral, 38% skin, and 17% nail; 60% resolved). Talquetamab achieved 71% response rate. After CAR-T, 88% responded (54% complete response), with low-grade toxicities (2 grade ≥3 CRS, 1 grade 3 ICANS, and 5% grade ≥3 infections). Two cases of facial palsy and 1 acute myeloid leukemia occurred. Talquetamab correlated with sustained soluble BCMA decline and peak CAR-T expansion around day 14. Talquetamab bridging appears safe, enabling the majority of difficult-to-treat patients to successfully proceed to BCMA CAR-T therapy.

B-cell maturation antigen (BCMA)-targeted therapies including both chimeric antigen receptor (CAR) T-cell therapies and bispecific antibodies (BsAbs), have revolutionized the treatment landscape for relapsed/refractory multiple myeloma (MM), offering both deep and durable responses, even in heavily pretreated patients. Despite these advances, most patients ultimately experience relapse. This is likely related to the development of resistance mechanisms that limit the long-term efficacy and durability of BCMA-targeted approaches. In this review, we examine the current landscape of BCMA-directed therapies, including Idecabtagene Vileucel, Ciltacabtagene Autoleucel, Teclistamab, and Elranatamab and explore the multifactorial mechanisms driving resistance. These mechanisms include tumor-intrinsic factors, host-related and tumor-extrinsic factors, and factors related to the tumor-microenvironment itself. We outline emerging strategies to overcome resistance, such as dual-targeting therapies, γ-secretase inhibitors, immune-checkpoint blockade, armored CAR T constructs, and novel combination regimens. Additionally, we discuss the role of therapy sequencing, emphasizing how prior exposure to BsAbs or CAR T-cell therapies may influence the efficacy of subsequent treatments. A deeper understanding of resistance biology, supported by integrated immune and genomic profiling, is essential to optimizing therapeutic durability and ultimately improve patient outcomes for patients with MM.

Talquetamab, a G protein–coupled receptor class C group 5 member D–targeting bispecific antibody for relapsed/refractory multiple myeloma (R/R MM), plus daratumumab, may lead to deeper and more durable responses than either therapy alone. In the phase 1b TRIMM-2 study, patients with R/R MM (at least 3 previous lines of therapy or double refractory to a proteasome inhibitor and an immunomodulatory drug) received subcutaneous talquetamab 0.4 mg/kg weekly (QW; “QW cohort”) or 0.8 mg/kg every other week (Q2W cohort) plus daratumumab 1800 mg per the approved schedule. The primary end point was safety. Secondary end points included overall response and duration of response. Progression-free survival was an exploratory end point. Sixty-five patients (median 5 previous lines of therapy; 61.5% triple-class refractory; 24.6% bispecific antibody exposed) received talquetamab plus daratumumab (QW, n = 14; Q2W, n = 51; median follow-up of 18.6 months). Most common adverse events were oral events, skin events, cytokine release syndrome, and infections. Grade 3 or 4 events occurred in 81.5%. Two patients had dose-limiting toxicities, both in the Q2W cohort (grade 3 stomatitis/oral mucositis, and grade 3 maculopapular rash). Responses occurred in 71.4% (QW cohort) and 82.4% (Q2W cohort) of patients. Median progression-free survival was 23.3 and 21.2 months, respectively, in each cohort. Pharmacodynamic results suggest the immunomodulatory action of daratumumab contributes to a conducive environment for talquetamab by reducing immunosuppressive cells. Talquetamab plus daratumumab demonstrated promising efficacy outcomes in patients with heavily pretreated disease, with a safety profile consistent with each agent as monotherapy. This trial was registered at www.clinicaltrials.gov as #NCT04108195.