The emergence of b-cell maturation antigen (BCMA) targeting immunotherapy in multiple myeloma

Impact of Frailty on Outcomes after Chimeric Antigen Receptor T Cell Therapy for Patients with Relapsed/Refractory Multiple Myeloma

The literature is limited regarding outcomes in older adults and frail patients receiving BCMA-directed chimeric antigen receptor T cell therapy (CAR-T) for relapsed or refractory multiple myeloma. Here we describe the safety and efficacy of CAR-T in these clinically important subgroups treated in a real-world setting. Frailty was defined as a frail score ≥2 using the simplified frailty index (score based on age + Eastern Cooperative Oncology Group [ECOG] Performance Status + Hematopoietic Cell Transplantation Comorbidity Index [HCT-CI]). Of the 136 patients analyzed (age range, 41 to 81 years), 83 (61%) were considered frail at the time of CAR-T infusion. Compared to the nonfrail group, the frail group had higher proportions of patients with renal insufficiency (18% versus 6%), high-risk cytogenetics (45% versus 35%), extramedullary disease (51% versus 43%), and ECOG Performance Status ≥2 (18% versus 2%), and worse HCT-CI (3 versus 1). Although patients in the frail group had a higher incidence of immune effector cell-associated neurotoxicity syndrome (ICANS) (39% versus 17%), the incidences of all- grade cytokine release syndrome (CRS), as well as high-grade CRS and ICANS, were similar in the 2 groups. With a median follow-up of 7 months, the median progression-free survival was 6.9 months in the frail group versus 11.1 months in the nonfrail group (P = .028). The median overall survival was 14 months in the frail group and was not reached in the nonfrail group (P = .025). This study highlights the tolerable safety and reasonable efficacy of CAR-T for frail myeloma patients in a real-world practice. Although the frail patients did not experience any excessive high-grade toxicities, they did have inferior efficacy outcomes.

The Effect of Belantamab Mafodotin on Primary Myeloma–Stroma Co-Cultures: Asymmetrical Mitochondrial Transfer between Myeloma Cells and Autologous Bone Marrow Stromal Cells

Belantamab mafodotin (belamaf) is an afucosylated monoclonal antibody conjugated to the microtubule disrupter monomethyl auristatin-F (MMAF) that targets B cell maturation antigen (BCMA) on the surface of malignant plasma cells. Belamaf can eliminate myeloma cells (MMs) through several mechanisms. On the one hand, in addition to inhibiting BCMA-receptor signaling and cell survival, intracellularly released MMAF disrupts tubulin polymerization and causes cell cycle arrest. On the other hand, belamaf induces effector cell-mediated tumor cell lysis via antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis. In our in vitro co-culture model, the consequences of the first mentioned mechanism can be investigated: belamaf binds to BCMA, reduces the proliferation and survival of MMs, and then enters the lysosomes of malignant cells, where MMAF is released. The MMAF payload causes a cell cycle arrest at the DNA damage checkpoint between the G2 and M phases, resulting in caspase-3-dependent apoptosis. Here, we show that primary MMs isolated from different patients can vary widely in terms of BCMA expression level, and inadequate expression is associated with extremely high resistance to belamaf according to our cytotoxicity assay. We also reveal that primary MMs respond to increasing concentrations of belamaf by enhancing the incorporation of mitochondria from autologous bone marrow stromal cells (BM-MSCs), and as a consequence, MMs become more resistant to belamaf in this way, which is similar to other medications we have analyzed previously in this regard, such as proteasome inhibitor carfilzomib or the BCL-2 inhibitor venetoclax. The remarkable resistance against belamaf observed in the case of certain primary myeloma cell cultures is a cause for concern and points towards the use of combination therapies to overcome the risk of antigen escape.

Newly approved and forthcoming T-cell-redirecting bispecific antibodies for the treatment of relapsed/refractory multiple myeloma

OBJECTIVE

Summarize the background, clinical trials, and place in therapy for the newly Food and Drug Administration (FDA) approved and forthcoming bispecific antibodies for relapsed/refractory (R/R) multiple myeloma.

DATA SOURCES

A search of the PubMed database was conducted using the following search terms: B-cell maturation antigen (BCMA), teclistamab, myeloma, BsAbs, GPRC5D, and bispecific. Ongoing clinical trials as well as abstracts from ASH and ASCO evaluating the efficacy and safety of novel agents were evaluated. Prescribing information was also reviewed.

SUMMARY

For patients with R/R multiple myeloma who have failed available therapies, treatment options are limited and survival is short. The FDA recently approved teclistamab, a T-cell-redirecting bispecific antibody, in patients with R/R multiple myeloma who have failed four prior lines of therapy. Teclistamab targets both CD3 expressed on T-cells and BCMA expressed on the surface of myeloma cells, mediating T-cell activation and lysis of plasma cells that express BCMA. Accelerated approval was granted based upon the results of the MajesTEC-1 study, which showed a durable response in a high proportion of heavily pretreated patients. Teclistamab is the first bispecific antibody approved for use in patients with multiple myeloma and the fourth approved agent targeting BCMA. Additional T-cell redirecting bispecific antibodies for use in multiple myeloma are also currently being studied.

CONCLUSION

Teclistamab is the newest agent granted FDA approval for use in R/R multiple myeloma and represents a promising new option for patients. Ongoing trials are investigating teclistamab and other novel bispecific antibodies in the upfront and R/R setting.

Prolonged hematological toxicity in patients receiving BCMA/CD19 CAR-T-cell therapy for relapsed or refractory multiple myeloma

Although chimeric antigen receptor T (CAR-T) cell therapy has been indicated to be effective in treating relapsed or refractory multiple myeloma (R/R MM), severe hematological toxicity (HT) remains an intractable issue. This study enrolled 54 patients with R/R MM following combined infusion of anti-CD19 and anti-BCMA CAR-T cells. The results showed that the rates of severe cytopenia were high, including severe neutropenia (28/54, 52%), severe anemia (15/54, 28%), and severe thrombocytopenia (18/54, 33%). Moreover, the incidence of prolonged HT (PHT) on Day 28 post-infusion was 52% (28/54), including 46% for severe neutropenia, 30% for severe anemia, and 31% for severe thrombocytopenia. Patients with PHT had a poorer median progression-free survival (PFS) and overall survival (OS) than patients without PHT (P=0.011; P=0.007). Furthermore, Cox regression analyses showed that PHT was an independent risk factor for PFS and OS. Univariate analyses showed that IFNγ (OR: 1.046; 95% CI: 1.002-1.093, P=0.042) and severe HT after lymphodepletion chemotherapy (OR: 0.082; 95% CI: 0.017-0.404; P=0.002) were independent risk factors for PHT. In conclusion, these results indicated that PHT was associated with poor outcomes following CAR-T-cell therapy in MM patients. Early detection and management of PHT would be beneficial for the prevention of life-threatening complications and improvement in the survival of patients after CAR-T-cell therapy.

Gaps and opportunities in the treatment of relapsed-refractory multiple myeloma: Consensus recommendations of the NCI Multiple Myeloma Steering Committee

A wide variety of new therapeutic options for Multiple Myeloma (MM) have recently become available, extending progression-free and overall survival for patients in meaningful ways. However, these treatments are not curative, and patients eventually relapse, necessitating decisions on the appropriate choice of treatment(s) for the next phase of the disease. Additionally, an important subset of MM patients will prove to be refractory to the majority of the available treatments, requiring selection of effective therapies from the remaining options. Immunomodulatory agents (IMiDs), proteasome inhibitors, monoclonal antibodies, and alkylating agents are the major classes of MM therapies, with several options in each class. Patients who are refractory to one agent in a class may be responsive to a related compound or to a drug from a different class. However, rules for selection of alternative treatments in these situations are somewhat empirical and later phase clinical trials to inform those choices are ongoing. To address these issues the NCI Multiple Myeloma Steering Committee formed a relapsed/refractory working group to review optimal treatment choices, timing, and sequencing and provide recommendations. Additional issues considered include the role of salvage autologous stem cell transplantation, risk stratification, targeted approaches for genetic subsets of MM, appropriate clinical trial endpoints, and promising investigational agents. This report summarizes the deliberations of the working group and suggests potential avenues of research to improve the precision, timing, and durability of treatments for Myeloma.