Road testing new CAR design strategies in multiple myeloma

BCMA-targeted therapies in multiple myeloma: advances, challenges and future prospects

Multiple myeloma (MM) is hematological cancer characterized by the aberrant proliferation of plasma cells. The treatment of MM has historically presented challenges, with a limited number of patients achieving sustained remission. Recent advancements in the therapeutic landscape have been marked by the development of B-cell maturation antigen (BCMA)-targeted therapies. BCMA, a plasma cell surface protein, is instrumental in the proliferation and survival of myeloma cells. This review aims to critically assess recent developments in BCMA-targeted therapies. The focus is on evaluating their efficacy and accessibility, as well as discussing potential future directions in this field. Emphasis is placed on chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies as emerging therapeutic strategies. An extensive review of current clinical trials and studies was conducted, centering on BCMA-targeted therapies. This encompassed an analysis of CAR T-cell therapies, which involve the genetic modification of patient T-cells to target BCMA, and bispecific antibodies that bind to both BCMA on myeloma cells and CD3 on T-cells. Clinical trials have demonstrated the efficacy of BCMA-targeted therapies in MM, with some patients achieving complete remission. However, these therapies are associated with adverse effects such as cytokine release syndrome and neurotoxicity. Research efforts are ongoing to reduce these side effects and enhance overall therapeutic effectiveness. BCMA-targeted therapies signify a notable advancement in MM treatment, offering prospects for prolonged remission and potentially curative outcomes. Despite existing challenges, these therapies represent a significant shift in MM management. The review highlights the necessity of ongoing research to optimize these therapies, improve patient outcomes, and increase treatment accessibility.

A review of recent clinical trials to evaluate disease-modifying therapies in the treatment of cardiac amyloidosis

Cardiac amyloidosis (CA) is a serious condition that results in infiltrative cardiomyopathy and heart failure with preserved ejection fraction (HFpEF) that is caused by the extracellular deposition of amyloid fibrils within heart tissue. While many important features of CA have been known for years, its prevalence in elderly patients with HF is increasingly being recognized. Plasma cells produce monoclonal immunoglobulin light chains which results in the formation and aggregation of amyloid fibrils that are responsible for AL amyloidosis. CA is classified as originating from either transthyretin (ATTR) or light chain (AL) amyloidosis. ATTR CA may result from a genetic mutation in the TTR gene, which is inherited (ATTRv), or from age-related deposition from wild-type ATTR (ATTRwt). Cardiac involvement in AL amyloidosis is attributed to either of two mechanisms: the extracellular deposition of amyloid fibril in the myocardium, or direct cardiotoxicity from the fibril aggregates. Typing of amyloid fibrils, a critical determinant of therapy, has also improved with wider availability of laser capture and mass spectrometry of histologic specimens. Specific and accurate evaluation of CA is now possible using cardiac magnetic resonance imaging and bone scintigraphy tracers. Survival in CA has improved markedly as novel chemotherapy agents have become available, but challenges remain in advanced disease. Broadening the amyloid-specific therapeutic landscape to include RNA inhibitors, fibril formation stabilizers and inhibitors, and immunotherapeutic targeting of amyloid deposits holds promise and may improve outcomes in systemic and cardiac amyloidoses. Treatment strategies for CA has recently undergone transformative changes, leading to some progress in outcomes for certain patients. Here, we discuss the basic features of CA as well as the emergence of novel, disease-modifying strategies that have been recently evaluated in clinical trials for the treatment of CA.

Advances in adoptive cellular immunotherapy and therapeutic breakthroughs in multiple myeloma

The basic idea of modulating the immune system to better recognize and fight tumor cells has led to the successful introduction of adoptive cellular immunotherapy (ACT). ACT-based treatment regimens, in which the patient's own immune cells are isolated and subsequently expanded (ex vivo) and reinfused, have also contributed significantly to the development of a personalized treatment strategy. Complementing this, the unprecedented advances in ACTs as chimeric antigen receptor (CAR)-T cell therapies and their derivatives such as CAR-NK, CAR-macrophages, CAR-γδT and CAR-NKT have further maximized the therapeutic outcomes. Herein, we provide a comprehensive overview of the development of ACTs in multiple myeloma (MM) and outline how they have evolved from an experimental form to a mainstay of standard clinical settings. Besides, we provide insights into cytokine-induced killer cell (CIK) therapy, an alternative form of ACT that (as CIK or CAR-CIK) has enormous potential in the clinical spectrum of MM. We also summarize the results of the major preclinical and clinical studies of adoptive cell therapy in MM and address the current challenges (such as cytokine release syndrome (CRS) and neurotoxicity) that limit its complete success in the cancer landscape.

CAR-T and CAR-NK as cellular cancer immunotherapy for solid tumors

In the past decade, chimeric antigen receptor (CAR)-T cell therapy has emerged as a promising immunotherapeutic approach for combating cancers, demonstrating remarkable efficacy in relapsed/refractory hematological malignancies in both pediatric and adult patients. CAR-natural killer (CAR-NK) cell complements CAR-T cell therapy by offering several distinct advantages. CAR-NK cells do not require HLA compatibility and exhibit low safety concerns. Moreover, CAR-NK cells are conducive to "off-the-shelf" therapeutics, providing significant logistic advantages over CAR-T cells. Both CAR-T and CAR-NK cells have shown consistent and promising results in hematological malignancies. However, their efficacy against solid tumors remains limited due to various obstacles including limited tumor trafficking and infiltration, as well as an immuno-suppressive tumor microenvironment. In this review, we discuss the recent advances and current challenges of CAR-T and CAR-NK cell immunotherapies, with a specific focus on the obstacles to their application in solid tumors. We also analyze in depth the advantages and drawbacks of CAR-NK cells compared to CAR-T cells and highlight CAR-NK CAR optimization. Finally, we explore future perspectives of these adoptive immunotherapies, highlighting the increasing contribution of cutting-edge biotechnological tools in shaping the next generation of cellular immunotherapy.

The TGFβ type I receptor kinase inhibitor vactosertib in combination with pomalidomide in relapsed/refractory multiple myeloma: a phase 1b trial

Functional blockade of the transforming growth factor-beta (TGFβ) signalling pathway improves the efficacy of cytotoxic and immunotherapies. Here, we conducted a phase 1b study (ClinicalTrials.gov., NCT03143985) to determine the primary endpoints of safety, tolerability, and maximal tolerated dose (200 mg twice daily) for the orally-available TGFβ type I receptor kinase inhibitor vactosertib in combination with pomalidomide in relapsed and/or refractory multiple myeloma (RRMM) patients who had received ≥2 lines of chemoimmunotherapy. Secondary endpoints demonstrated sustained clinical responses, favorable pharmacokinetic parameters and a 6-month progression-free survival of 82%. Vactosertib combined with pomalidomide was well-tolerated at all dose levels and displayed a manageable adverse event profile. Exploratory analysis indicated that vactosertib co-treatment with pomalidomide also reduced TGFβ levels in patient bone marrow as well as the level of CD8+ T-cells that expressed the immunoinhibitory marker PD-1. In vitro experiments indicated that vactosertib+pomalidomide co-treatment decreased the viability of MM cell lines and patient tumor cells, and increased CD8+ T-cell cytotoxic activity. Vactosertib is a safe therapeutic that demonstrates tumor-intrinsic activity and can overcome immunosuppressive challenges within the tumor microenvironment to reinvigorate T-cell fitness. Vactosertib offers promise to improve immunotherapeutic responses in heavily-pretreated MM patients refractory to conventional agents.

The dilemmas and possible solutions for CAR-T cell therapy application in solid tumors

Chimeric antigen receptor T (CAR-T) cell therapy, as an adoptive immunotherapy, is playing an increasingly important role in the treatment of malignant tumors. CAR-T cells are referred to as "living drugs" as they not only target tumor cells directly, but also induce long-term immune memory that has the potential to provide long-lasting protection. CD19.CAR-T cells have achieved complete response rates of over 90 % for acute lymphoblastic leukemia and over 60 % for non-Hodgkin's lymphoma. However, the response rate of CAR-T cells in the treatment of solid tumors remains extremely low and the side effects potentially severe. In this review, we discuss the limitations that the solid tumor microenvironment poses for CAR-T application and the solutions that are being developed to address these limitations, in the hope that in the near future, CAR-T cell therapy for solid tumors can attain the same success rates as are now being seen clinically for hematological malignancies.

Combination of CAR‑T cell therapy and radiotherapy: Opportunities and challenges in solid tumors (Review)

Chimeric antigen receptor (CAR) T cell therapy has emerged as a new and breakthrough cancer immunotherapy. Although CAR-T cell therapy has made significant progress clinically in patients with refractory or drug-resistant hematological malignancies, there are numerous challenges in its application to solid tumor therapy, including antigen escape, severe toxic reactions, abnormal vascularization, tumor hypoxia, insufficient infiltration of CAR-T cells and immunosuppression. As a conventional mode of anti-tumor therapy, radiotherapy has shown promising effects in combination with CAR-T cell therapy by enhancing the specific immunity of endogenous target antigens, which promoted the infiltration and expansion of CAR-T cells and improved the hypoxic tumor microenvironment. This review focuses on the obstacles to the application of CAR-T technology in solid tumor therapy, the potential opportunities and challenges of combined radiotherapy and CAR-T cell therapy, and the review of recent literature to evaluate the best combination for the treatment of solid tumors.

Shutting off the fuel supply to target metabolic vulnerabilities in multiple myeloma

Pathways that govern cellular bioenergetics are deregulated in tumor cells and represent a hallmark of cancer. Tumor cells have the capacity to reprogram pathways that control nutrient acquisition, anabolism and catabolism to enhance their growth and survival. Tumorigenesis requires the autonomous reprogramming of key metabolic pathways that obtain, generate and produce metabolites from a nutrient-deprived tumor microenvironment to meet the increased bioenergetic demands of cancer cells. Intra- and extracellular factors also have a profound effect on gene expression to drive metabolic pathway reprogramming in not only cancer cells but also surrounding cell types that contribute to anti-tumor immunity. Despite a vast amount of genetic and histologic heterogeneity within and between cancer types, a finite set of pathways are commonly deregulated to support anabolism, catabolism and redox balance. Multiple myeloma (MM) is the second most common hematologic malignancy in adults and remains incurable in the vast majority of patients. Genetic events and the hypoxic bone marrow milieu deregulate glycolysis, glutaminolysis and fatty acid synthesis in MM cells to promote their proliferation, survival, metastasis, drug resistance and evasion of immunosurveillance. Here, we discuss mechanisms that disrupt metabolic pathways in MM cells to support the development of therapeutic resistance and thwart the effects of anti-myeloma immunity. A better understanding of the events that reprogram metabolism in myeloma and immune cells may reveal unforeseen vulnerabilities and advance the rational design of drug cocktails that improve patient survival.

Targeting TGF-β signaling in the multiple myeloma microenvironment: Steering CARs and T cells in the right direction

Multiple myeloma (MM) remains a lethal hematologic cancer characterized by the expansion of transformed plasma cells within the permissive bone marrow (BM) milieu. The emergence of relapsed and/or refractory MM (RRMM) is provoked through clonal evolution of malignant plasma cells that harbor genomic, metabolic and proteomic perturbations. For most patients, relapsed disease remains a major cause of overall mortality. Transforming growth factors (TGFs) have pleiotropic effects that regulate myelomagenesis as well as the emergence of drug resistance. Moreover, TGF-β modulates numerous cell types present with the tumor microenvironment, including many immune cell types. While numerous agents have been FDA-approved over the past 2 decades and significantly expanded the treatment options available for MM patients, the molecular mechanisms responsible for drug resistance remain elusive. Multiple myeloma is uniformly preceded by a premalignant state, monoclonal gammopathy of unknown significance, and both conditions are associated with progressive deregulation in host immunity characterized by reduced T cell, natural killer (NK) cell and antigen-presenting dendritic cell (DC) activity. TGF-β promotes myelomagenesis as well as intrinsic drug resistance by repressing anti-myeloma immunity to promote tolerance, drug resistance and disease progression. Hence, repression of TGF-β signaling is a prerequisite to enhance the efficacy of current and future immunotherapeutics. Novel strategies that incorporate T cells that have been modified to express chimeric antigen receptor (CARs), T cell receptors (TCRs) and bispecific T cell engagers (BiTEs) offer promise to block TGF-β signaling, overcome chemoresistance and enhance anti-myeloma immunity. Here, we describe the effects of TGF-β signaling on immune cell effectors in the bone marrow and emerging strategies to overcome TGF-β-mediated myeloma growth, drug resistance and survival.