Bispecific CS1-BCMA CAR-T cells are clinically active in relapsed or refractory multiple myeloma

T cell-redirecting therapies in hematological malignancies: Current developments and novel strategies for improved targeting

T cell-redirecting therapies (TCRTs), such as chimeric antigen receptor (CAR) or T cell receptor (TCR) T cells and T cell engagers, have emerged as a highly effective treatment modality, particularly in the B and plasma cell-malignancy setting. However, many patients fail to achieve deep and durable responses; while the lack of truly unique tumor antigens, and concurrent on-target/off-tumor toxicities, have hindered the development of TCRTs for many other cancers. In this review, we discuss the recent developments in TCRT targets for hematological malignancies, as well as novel targeting strategies that aim to address these, and other, challenges.

Just scratching the surface: novel treatment approaches for multiple myeloma targeting cell membrane proteins

A better understanding of the roles of the adaptive and innate immune systems in the oncogenesis of cancers including multiple myeloma (MM) has led to the development of novel immune-based therapies. B cell maturation antigen (BCMA), G protein-coupled receptor family C group 5 member D (GPRC5D) and Fc receptor-like protein 5 (FcRL5, also known as FcRH5) are cell-surface transmembrane proteins expressed by plasma cells, and have been identified as prominent immunotherapeutic targets in MM, with promising activity demonstrated in patients with heavily pretreated relapsed and/or refractory disease. Indeed, since 2020, antibody-drug conjugates, bispecific T cell engagers and autologous chimeric antigen receptor T cells targeting BCMA or GPRC5D have been approved for the treatment of relapsed and/or refractory MM. However, responses to these therapies are not universal, and acquired resistance invariably occurs. In this Review, we discuss the various immunotherapeutic approaches targeting BCMA, GPRC5D and FcRL5 that are currently either available or in clinical development for patients with MM. We also review the mechanisms underlying resistance to such therapies, and discuss potential strategies to overcome these mechanisms and improve patient outcomes.

Case report: Dual-targeted BCMA and CS1 CAR-T-cell immunotherapy in recurrent and refractory extramedullary multiple myeloma

Background

The development of CAR-T-cell immunotherapy has notably elevated the efficacy of treating multiple myeloma. Currently, a variety of targets, including BCMA, CS1, CD38, FcRH5, and GPRC5D, are being investigated. Despite these significant advancements, challenges such as antigen escape, limited persistence of CAR-T cells, and the intricate nature of the tumor microenvironment persist, leading to relapses following treatment.

Case presentation

We report the case of a patient with recurrent and refractory multiple myeloma (RRMM) who developed a substantial extramedullary plasmacytoma in the muscles of the lower limb following multiple rounds of radiotherapy and chemotherapy. The patient underwent CAR-T-cell immunotherapy targeting BCMA and CS1; however, the tumor progressed despite treatment. Surgical resection of the extramedullary plasmacytoma was subsequently performed. Upon comparison of the tumor tissue with the adjacent tissue, increased expression of MYBL2 was noted in the tumor tissue, potentially contributing to the lack of improvement in extramedullary relapse after dual-targeted CAR-T cell therapy.

Conclusions

In patients with recurrent and refractory multiple myeloma who underwent multiple cycles of chemotherapy and radiotherapy, dual-targeted CAR-T cell therapy aimed at BCMA and CS1 failed to effectively manage extramedullary relapse. Elevated expression of MYBL2 in multiple myeloma correlates with a poorer prognosis.

Fast and furious: Changing gears on the road to cure with chimeric antigen receptor T cells in multiple myeloma

Based on the pivotal KarMMa-1 and CARTITUDE-1 studies, Idecabtagene vicleucel (Ide-cel) and Ciltacabtagene autoleucel (Cilta-cel) have been approved to treat multiple myeloma patients, who have been exposed to at least 1 proteasome inhibitor, immunomodulatory drug and anti-CD38 antibody after 4 or 3 lines of therapy, respectively. The unprecedented rates of deep and long-lasting remissions have been meanwhile confirmed in multiple real-world analyses and more recently, the KarMMa-3 and CARTITUDE-4 studies lead to the approval in earlier lines of therapy. It is currently believed that ultimately all patients with relapsed/refractory multiple myeloma experience relapse after anti-BCMA CAR T-cell therapies. There is a plethora of CAR T-cell therapies targeting novel antigens, with the aim to overcome current CAR T-cell resistance. In this review, we will summarize current evidence of novel antigens and their clinical potential. Together with current CAR T-cell therapy and T-cell engagers, these approaches might lead us to the next frontier in multiple myeloma: total immunotherapy and the road to chemotherapy-free cure.

Multiple myeloma: signaling pathways and targeted therapy

Multiple myeloma (MM) is the second most common hematological malignancy of plasma cells, characterized by osteolytic bone lesions, anemia, hypercalcemia, renal failure, and the accumulation of malignant plasma cells. The pathogenesis of MM involves the interaction between MM cells and the bone marrow microenvironment through soluble cytokines and cell adhesion molecules, which activate various signaling pathways such as PI3K/AKT/mTOR, RAS/MAPK, JAK/STAT, Wnt/β-catenin, and NF-κB pathways. Aberrant activation of these pathways contributes to the proliferation, survival, migration, and drug resistance of myeloma cells, making them attractive targets for therapeutic intervention. Currently, approved drugs targeting these signaling pathways in MM are limited, with many inhibitors and inducers still in preclinical or clinical research stages. Therapeutic options for MM include non-targeted drugs like alkylating agents, corticosteroids, immunomodulatory drugs, proteasome inhibitors, and histone deacetylase inhibitors. Additionally, targeted drugs such as monoclonal antibodies, chimeric antigen receptor T cells, bispecific T-cell engagers, and bispecific antibodies are being used in MM treatment. Despite significant advancements in MM treatment, the disease remains incurable, emphasizing the need for the development of novel or combined targeted therapies based on emerging theoretical knowledge, technologies, and platforms. In this review, we highlight the key role of signaling pathways in the malignant progression and treatment of MM, exploring advances in targeted therapy and potential treatments to offer further insights for improving MM management and outcomes.

Beyond BCMA: the next wave of CAR T cell therapy in multiple myeloma

Chimeric antigen receptor (CAR) T cell therapy has transformed the treatment landscape of relapsed/refractory multiple myeloma. The current Food and Drug Administration approved CAR T cell therapies idecabtagene vicleucel and ciltacabtagene autoleucel both target B cell maturation antigen (BCMA), which is expressed on the surface of malignant plasma cells. Despite deep initial responses in most patients, relapse after anti-BCMA CAR T cell therapy is common. Investigations of acquired resistance to anti-BCMA CAR T cell therapy are underway. Meanwhile, other viable antigenic targets are being pursued, including G protein-coupled receptor class C group 5 member D (GPRC5D), signaling lymphocytic activation molecule family member 7 (SLAMF7), and CD38, among others. CAR T cells targeting these antigens, alone or in combination with anti-BCMA approaches, appear to be highly promising as they move from preclinical studies to early phase clinical trials. This review summarizes the current data with novel CAR T cell targets beyond BCMA that have the potential to enter the treatment landscape in the near future.

Immune Therapies in AL Amyloidosis-A Glimpse to the Future

Light-chain (AL) amyloidosis is a rare plasma cell disorder characterized by the deposition of misfolded immunoglobulin light chains in target organs, leading to multi-organ dysfunction. Treatment approaches have historically mirrored but lagged behind those of multiple myeloma (MM). Recent advancements in MM immunotherapy are gradually being evaluated and adopted in AL amyloidosis. This review explores the current state of immunotherapeutic strategies in AL amyloidosis, including monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor T-cell therapy. We discuss the unique challenges and prospects of these therapies in AL amyloidosis, including the exposure of frail AL amyloidosis patients to immune-mediated toxicities such as cytokine release syndrome (CRS) and immune effector-cell-associated neurotoxicity syndrome (ICANS), as well as their efficacy in promoting rapid and deep hematologic responses. Furthermore, we highlight the need for international initiatives and compassionate programs to provide access to these promising therapies and address critical unmet needs in AL amyloidosis management. Finally, we discuss future directions, including optimizing treatment sequencing and mitigating toxicities, to improve outcomes for AL amyloidosis patients.

CS1 Expression Pattern in NK Cells and Correlated Factors in Plasma Cell dyscrasias: Implications for Elotuzumab Therapy and CAR-T Efficacy

Treatment with elotuzumab alone has no discernible antitumor effect and progress in chimeric antigen receptor T cells (CAR-T) therapy targeting CS1 is relatively slow. A retrospective analysis was performed on 236 patients with multiple myeloma (MM) and 30 patients with other plasma cell dyscrasias (PCDs). CS1 expression in NK cells, lymphocytes, and monoclonal plasma cells was assessed using multiparameter flow cytometry. Furthermore, new explorations were undertaken regarding the antitumor applications of elotuzumab. Patients with MM had significantly higher CS1 expression levels in plasma cells than other patients with PCDs, with no significant differences between lymphocytes and NK cells. In both patients with MM and other PCDs, CS1 expression was significantly higher in plasma cells than in NK cells and lymphocytes. Univariate and multivariate analyses revealed a significant correlation between CS1 expression in plasma (r = 0.60; P < 0.001) and NK (r = 0.79; P < 0.001) cells. Factors such as cytogenetic abnormalities, disease progression, and survival were not associated with CS1 expression in NK cells. Moreover, this study showed that elotuzumab strongly increases the cytotoxicity of NK cells against non-plasma and plasma tumor cells independent of their CS1 expression level. This underscores the potential of elotuzumab in combination with NK cells as an effective therapeutic strategy against a broad spectrum of tumor types.

Update on the current and future use of CAR-T to treat multiple myeloma

Chimeric antigen receptor T-cell (CAR-T) therapy has become an important intervention in the management of relapsed and relapsed/refractory multiple myeloma (MM). Currently, B-cell maturation antigen (BCMA) is the most targeted surface protein due to its ubiquitous expression on plasma cells, with increasing expression of this essential transmembrane protein on malignant plasma cells as patients develop more advanced disease. This review will explore the earliest CAR-T trials in myeloma, discuss important issues involved in CAR-T manufacturing and processing, as well as review current clinical trials that led to the approval of the two commercially available CAR-T products, Idecabtagene vicleucel and ciltacabtagene autoleucel. The most recent data from trials investigating the use of CAR-T as an earlier line of therapy will be presented. Finally, the problem of relapses after CAR-T will be presented, including several theories as to why CAR-T therapies fail and possible clinical caveats. The next generation of MM-specific CAR-T will likely include new targets such as G-protein-coupled receptor class C, Group 5, member D (GPRC5D) and signaling lymphocyte activation molecular Family 7 (SLAMF7). The role of CAR-T in the treatment of MM will undoubtedly increase exponentially in the next decade.

Exploring cellular immunotherapy platforms in multiple myeloma

Despite major advances in therapeutic platforms, most patients with multiple myeloma (MM) eventually relapse and succumb to the disease. Among the novel therapeutic options developed over the past decade, genetically engineered T cells have a great deal of potential. Cellular immunotherapies, including chimeric antigen receptor (CAR) T cells, are rapidly becoming an effective therapeutic modality for MM. Marrow-infiltrating lymphocytes (MILs) derived from the bone marrow of patients with MM are a novel source of T cells for adoptive T-cell therapy, which robustly and specifically target myeloma cells. In this review, we examine the recent innovations in cellular immunotherapies, including the use of dendritic cells, and cellular tools based on MILs, natural killer (NK) cells, and CAR T cells, which hold promise for improving the efficacy and/or reducing the toxicity of treatment in patients with MM.

Integrating CAR-T cell therapy into the management of DLBCL: what we are learning

INTRODUCTION

Chimeric Antigen Receptor ;(CAR) T cells therapies have become part of the standard of care for patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). The weakness of CAR-T therapies is that there are no comparative clinical trials, although many publications based on real-life data have confirmed the results obtained in pivotal studies. After several years of the commercialization of CAR-T, some points still need to be fully clarified. Healthcare professionals have questions about identifying patients who may benefit from therapy. There are aspects inherent in the accessibility of care related to improved relationships between CAR-T-delivering and referral centers.

AREAS COVERED

Open questions are inherent in the salvage and bridge therapy, predictive criteria for response and persistence of CAR-T after infusion. Managing toxicities remain a top priority and one of the points on which further knowledge is needed.

EXPERT OPINION

This review aims to describe the current landscape of CAR-T cells in DLBCL, outline their outcomes and toxicities, and explain the outstanding questions that remain to be addressed.