Anti-BCMA CAR T-Cell Therapy bb2121 in Relapsed or Refractory Multiple Myeloma

Rare case of non-producer variant of plasma cell dyscrasias with circulating plasma cells

Non-producing variant of plasma cell disorders with circulating plasma cells is an aggressive variant of plasma cell dyscrasias with relatively poor outcomes. A 75-year-old man was admitted due to anaemia (90 g/L) and thrombocytopenia (9×10⁹/L). Comprehensive metabolic panel showed creatinine of 1.34 mg/dL, total protein of 6 g/dL, and corrected calcium was normal. Peripheral smear review showed 8% circulating atypical plasmacytoid cells. Bone marrow biopsy (BMB) confirmed plasma cell myeloma involving 90%-95% of bone marrow cellularity. Serum protein electrophoresis showed no monoclonal protein. Due to aggressive biology of non-producer variant and outcomes based on circulating plasma cells, he was started on VD-PACE (bortezomib, dexamethasone, cisplatin, doxorubicin, cyclophosphamide and etoposide) chemotherapy. BMB after cycle 1 chemotherapy showed no morphologic, immunophenotypic, or flow cytometric features of a plasma cell neoplasm. Given excellent treatment response cycle 2 was changed to VRD (bortezomib, lenalidomide and dexamethasone). Following two cycles of VRD, he underwent autologous haematopoietic cell transplantation. Day 80 BMB suggested stringent complete response.

Understanding the Mechanisms of Resistance to CAR T-Cell Therapy in Malignancies

Taking advantage of the immune system to exert an antitumor effect is currently a novel approach in cancer therapy. Adoptive transfer of T cells engineered to express chimeric antigen receptors (CARs) targeting a desired antigen has shown extraordinary antitumor activity, especially in refractory and relapsed B-cell malignancies. The most representative in this respect, as well as the most successful example, is CD19 CAR T-cell therapy in B-cell acute lymphoblastic leukemia (B-ALL). However, with the widespread use of CAR T-cell therapy, problems of resistance and relapse are starting to be considered. This review provides a comprehensive picture of the mechanisms of resistance to CAR T-cell therapy from three aspects, namely, CAR T-cell factors, tumor factors, and tumor microenvironment factors, offering insights for improving CAR T-cell therapy.

Chimeric antigen receptor T cell therapies for multiple myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy and remains incurable despite the advent of numerous new drugs such as proteasome inhibitors (PIs), immunomodulatory agents (IMiDs), and monoclonal antibodies. There is an unmet need to develop novel therapies for refractory/relapsed MM. In the past few years, chimeric antigen receptor (CAR)-modified T cell therapy for MM has shown promising efficacy in preclinical and clinical studies. Furthermore, the toxicities of CAR-T cell therapy are manageable. This article summarizes recent developments of CAR-T therapy in MM, focusing on promising targets, new technologies, and new research areas. Additionally, a comprehensive overview of antigen selection is presented along with preliminary results and future directions of CAR-T therapy development.

Adeno-Associated Viral Vectors for Homology-Directed Generation of CAR-T Cells

Immunotherapy with T cells expressing chimeric antigen receptors (CAR) is an emerging and promising treatment against refractory cancers. However, the currently adopted methods of modification of T cells pose a risk of insertional oncogenesis because lentiviral and retroviral vectors integrate the CAR transgene in a semi-random fashion. In addition, this therapy is only available using autologous cells, which create problems in production and limit the access for patients who have their T cells depleted. One modification method that shows the ability to overcome both drawbacks is the knock-in of the CAR simultaneously knocking-out genes that prevent allogeneic therapy, such as the endogenous T cell receptor. In this mini-review, the authors present recent efforts to develop safer universal CAR-T cells. More specifically, the combined application of target-directed nucleases, which create a double-strand break at a specific genome locus, and the delivery of CAR DNA via adeno-associated viral vectors for subsequent integration via homologous recombination and silencing of the targeted gene is focused on.

Cancer biomarkers for targeted therapy

Tumor-associated antigens (TAA) or cancer biomarkers are major targets for cancer therapies. Antibody- based agents targeting the cancer biomarkers include monoclonal antibodies (MoAbs), radiolabeled MoAbs, bispecific T cell engagers, and antibody-drug conjugates. Antibodies targeting CD19, CD20, CD22, CD30, CD33, CD38, CD79B and SLAMF7 are in clinical applications for hematological malignancies. CD123, CLL-1, B cell maturation antigen, and CD138 are targets for cancer immunotherapeutic agents, including the chimeric antigen receptor - engineered T cells. Immune checkpoint inhibitors (ICIs) against PD-1, PD-L1, and CTLA-4 have led to the revolution of cancer immunotherapy. More ICIs targeting IDO, LAG3, TIM-3, TIGIT, SIGLECs, VISTA and CD47 are being explored. Small molecule inhibitors (SMIs) against tyrosine kinase oncoproteins such as BCR-ABL, JAK2, Bruton tyrosine kinase, FLT3, EGFR, ALK, HER2, VEGFR, FGFR, MEK, and MET have fundamentally changed the landscape of cancer therapy. SMIs against BCL-2, IDHs, BRAF, PI3 kinase, mTOR, PARP, and CDKs have become the mainstay in the treatment of a variety of cancer types. To reduce and avoid off-tumor toxicities, cancer-specific TAAs such as CD33 are being manufactured through systems biology approach. Search for novel biomarkers and new designs as well as delivery methods of targeted agents are fueling the next wave of advances in cancer therapy.

CAR T-cell therapy: is it prime time in myeloma?

Chimeric antigen receptor (CAR) T cells have shown promising activity in hematological malignancies and are being studied for the treatment of multiple myeloma, as well. B-cell maturation antigen, which is widely and almost exclusively expressed on plasma cells and B cells, is a promising target. Other targets being evaluated include CD19, CD38, CD138, signaling lymphocyte activation molecule or CS1, light chain, GPRC5D, and NKG2D. Early clinical studies have shown promising response rates in heavily pretreated patients, but relapses have occurred. Cytokine release syndrome and neurotoxicity have been observed in the majority of patients but are mostly grades 1 and 2. Relapse may be mediated by antigen escape and the limited persistence of CAR T cells. CAR T-cell constructs that target multiple antigens/epitopes or constructs with longer persistence due to a higher proportion of memory phenotype T cells may decrease the rates of relapse. Allogeneic CAR T cells that offer "off-the-shelf" options are also being developed. The challenges in integrating CAR T cells in myeloma therapy include disease relapse, adverse effects, cost, and identifying the right patient population. Longer-term data on efficacy and toxicity are needed before CAR T cells are ready for prime time in myeloma.

CAR-T "the living drugs", immune checkpoint inhibitors, and precision medicine: a new era of cancer therapy

New advances in the design and manufacture of monoclonal antibodies, bispecific T cell engagers, and antibody-drug conjugates make the antibody-directed agents more powerful with less toxicities. Small molecule inhibitors are routinely used now as oral targeted agents for multiple cancers. The discoveries of PD1 and PD-L1 as negative immune checkpoints for T cells have led to the revolution of modern cancer immunotherapy. Multiple agents targeting PD1, PD-L1, or CTLA-4 are widely applied as immune checkpoint inhibitors (ICIs) which alleviate the suppression of immune regulatory machineries and lead to immunoablation of once highly refractory cancers such as stage IV lung cancer. Tisagenlecleucel and axicabtagene ciloleucel are the two approved CD19-targeted chimeric antigen receptor (CAR) T cell products. Several CAR-T cell platforms targeting B cell maturation antigen (BCMA) are under active clinical trials for refractory and/or relapsed multiple myeloma. Still more targets such as CLL-1, EGFR, NKG2D and mesothelin are being directed in CAR-T cell trials for leukemia and solid tumors. Increasing numbers of novel agents are being studied to target cancer-intrinsic oncogenic pathways as well as immune checkpoints. One such an example is targeting CD47 on macrophages which represents a "do-not-eat-me" immune checkpoint. Fueling the current excitement of cancer medicine includes also TCR- T cells, TCR-like antibodies, cancer vaccines and oncolytic viruses.

γ-Secretase inhibition increases efficacy of BCMA-specific chimeric antigen receptor T cells in multiple myeloma

B-cell maturation antigen (BCMA) is a validated target for chimeric antigen receptor (CAR) T-cell therapy in multiple myeloma (MM). Despite promising objective response rates, most patients relapse, and low levels of BCMA on a subset of tumor cells has been suggested as a probable escape mechanism. BCMA is actively cleaved from the tumor cell surface by the ubiquitous multisubunit γ-secretase (GS) complex, which reduces ligand density on tumor cells for CAR T-cell recognition and releases a soluble BCMA (sBCMA) fragment capable of inhibiting CAR T-cell function. Sufficient sBCMA can accumulate in the bone marrow of MM patients to inhibit CAR T-cell recognition of tumor cells, and potentially limit efficacy of BCMA-directed adoptive T-cell therapy. We investigated whether blocking BCMA cleavage by small-molecule GS inhibitors (GSIs) could augment BCMA-targeted CAR T-cell therapy. We found that exposure of myeloma cell lines and patient tumor samples to GSIs markedly increased surface BCMA levels in a dose-dependent fashion, concurrently decreased sBCMA concentrations, and improved tumor recognition by CAR T cells in vitro. GSI treatment of MM tumor-bearing NOD/SCID/γc-/- mice increased BCMA expression on tumor cells, decreased sBCMA in peripheral blood, and improved antitumor efficacy of BCMA-targeted CAR T-cell therapy. Importantly, short-term GSI administration to MM patients markedly increases the percentage of BCMA+ tumor cells, and the levels of BCMA surface expression in vivo. Based on these data, a US Food and Drug Administration (FDA)-approved clinical trial has been initiated, combining GSI with concurrent BCMA CAR T-cell therapy. This trial was registered at www.clinicaltrials.gov as #NCT03502577.

Recent updates on CAR T clinical trials for multiple myeloma

Proteasome inhibitors, immunomodulatory agents and monoclonal antibodies have dramatically changed the natural history of multiple myeloma (MM). However, most patients eventually suffer a relapse and succumb to the disease. Chimeric antigen receptor (CAR) engineered T cells targeting B cell maturation antigen (BCMA), CD138, CS1 glycoprotein antigen (SLAMF7) and light chains are in active development for therapy of refractory /relapsed (RR) MM. CD19- targeted CAR T cells in conjunction with autologous stem cell transplantation also showed activity in RRMM. Dual- target CAR T cells are in clinical trials for RRMM. This review summarized the recent updates of ongoing CAR T clinical trials for multiple myeloma.

CD19 chimeric antigen receptor-T cells in B-cell leukemia and lymphoma: current status and perspectives

The approval of tisagenlecleucel and axicabtagene ciloleucel represents a breakthrough in the field of immune and cellular therapy for hematologic malignancies. These anti-CD19 chimeric antigen receptor-T cells (CAR) proved to be highly effective in the treatment of relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) and specific histologic subtypes of B-cell non-Hodgkin lymphomas. This expert review aims to summarize the current available research evidence in this field, with a special focus on the different challenges faced by treating physicians, and we also provide future perspectives.

Monoclonal Antibody Therapies in Multiple Myeloma: A Challenge to Develop Novel Targets

The treatment options in multiple myeloma (MM) has changed dramatically over the past decade with the development of novel agents such as proteasome inhibitors (PIs); bortezomib and immunomodulatory drugs (IMiDs); thalidomide, and lenalidomide which revealed high efficacy and improvement of overall survival (OS) in MM patients. However, despite these progresses, most patients relapse and become eventually refractory to these therapies. Thus, the development of novel, targeted immunotherapies has been pursued aggressively. Recently, next-generation PIs; carfilzomib and ixazomib, IMiD; pomalidomide, histone deacetylase inhibitor (HDADi); panobinostat and monoclonal antibodies (MoAbs); and elotuzumab and daratumumab have emerged, and especially, combination of mAbs plus novel agents has led to dramatic improvements in the outcome of MM patients. The field of immune therapies has been accelerating in the treatment of hematological malignancies and has also taken center stage in MM. This review focuses on an overview of current status of novel MoAb therapy including bispecific T-cell engager (BiTE) antibody (BsAb), antibody-drug conjugate (ADC), and chimeric antigen receptor (CAR) T cells, in relapsed or refractory MM (RRMM). Lastly, investigational novel MoAb-based therapy to overcome immunotherapy resistance in MM is shown.

The promise of chimeric antigen receptor (CAR) T cell therapy in multiple myeloma

A cure for multiple myeloma (MM), a malignancy of plasma cells, remains elusive. Nearly all myeloma patients will eventually relapse and develop resistance to currently available treatments. There is an unmet medical need to develop novel and effective therapies that can induce sustained responses. Early phase clinical trials using chimeric antigen receptor (CAR) T cell therapy have shown great promise in the treatment of relapsed and/or refractory MM. In this review article, we provide an overview of the CAR constructs, the gene transfer vector systems, and approaches for T cell activation and expansion. We then summarize the outcomes of several early phase clinical trials of CAR T cell therapy in MM and the novel CAR T targets that are under development. Finally, we explore the potential mechanisms that result in disease relapse after CAR T therapy and propose future directions in CAR T therapy in MM.

BAFF inhibition in SLE-Is tolerance restored?

The B cell activating factor (BAFF) inhibitor, belimumab, is the first biologic drug approved for the treatment of SLE, and exhibits modest, but durable, efficacy in decreasing disease flares and organ damage. BAFF and its homolog APRIL are TNF-like cytokines that support the survival and differentiation of B cells at distinct developmental stages. BAFF is a crucial survival factor for transitional and mature B cells that acts as rheostat for the maturation of low-affinity autoreactive cells. In addition, BAFF augments innate B cell responses via complex interactions with the B cell receptor (BCR) and Toll like receptor (TLR) pathways. In this manner, BAFF impacts autoreactive B cell activation via extrafollicular pathways and fine tunes affinity selection within germinal centers (GC). Finally, BAFF and APRIL support plasma cell survival, with differential impacts on IgM- and IgG-producing populations. Therapeutically, BAFF and combined BAFF/APRIL inhibition delays disease onset in diverse murine lupus strains, although responsiveness to BAFF inhibition is model dependent, in keeping with heterogeneity in clinical responses to belimumab treatment in humans. In this review, we discuss the mechanisms whereby BAFF/APRIL signals promote autoreactive B cell activation, discuss whether altered selection accounts for therapeutic benefits of BAFF inhibition, and address whether new insights into BAFF/APRIL family complexity can be exploited to improve human lupus treatments.

Cytokine Release Syndrome: Current Perspectives

Chimeric antigen receptor T cell (CART) therapy represents a novel and a paradigm-shifting approach to treating cancer. Recent clinical successes have widened the applicability of CD19 CART cells for the treatment of relapsed/refractory B-cell NHL, namely tisagenleclucel and axicabtagene ciloleucel. Tisagenleclucel is also approved for relapsed and/or refractory B-ALL up to age 25. CART therapy is associated with unique and potentially life-threatening toxicities, notably cytokine release syndrome (CRS). A better understanding of the pathogenesis of CRS is crucial to ensure proper management. In this review, CRS definitions, profiles, risk factors and grading systems are discussed. Finally, current and novel investigational approaches and therapies for CRS are summarized.

What is new in the treatment of Waldenstrom macroglobulinemia?

Waldenstrom macroglobulinemia (WM) is a rare type of non-Hodgkin lymphoma. The diagnosis of WM is established by the presence of lymphoplasmacytic lymphoma in the bone marrow or other organs, a monoclonal IgM paraproteinemia and the recurrent MYD88 L265P somatic mutation. Some patients with WM can be asymptomatic, in which case treatment is not indicated. However, most patients with WM will become symptomatic during the course of the disease, due to anemia, hyperviscosity, neuropathy, or other processes, necessitating therapy. Current treatment options for symptomatic WM patients include alkylating agents, proteasome inhibitors and anti-CD20 monoclonal antibodies. The approval of the oral Bruton tyrosine kinase (BTK) inhibitor ibrutinib alone and in combination with rituximab has expanded the treatment options for WM patients. The present Perspective would focus on exciting treatment strategies under development for WM patients, such as proteasome inhibitors (e.g., ixazomib), BTK inhibitors (e.g., acalabrutinib, zanubrutinib, vecabrutinib), BCL2 inhibitors (e.g., venetoclax), and anti-CXCR4 antibodies (e.g., ulocuplumab), among others. It is certainly an exciting time for WM therapy development with novel and promising treatment options in the horizon.

Is autologous stem cell transplantation still relevant for multiple myeloma?

PURPOSE OF REVIEW

Autologous stem cell transplantation has been the standard of care in myeloma treatment for many years, but the availability of newer antimyeloma drugs and the emerging data from chimeric antigen receptor (CAR) T-cell clinical studies make us question the relevance of it. The purpose of this review is to go over recent data and to reassess the current status of autologous stem cell transplantation as a standard of care.

RECENT FINDINGS

Autologous stem cell transplantation can be safely performed for elderly patients and there is no absolute age limit. Recent data on BEAM (Carmustine, Etoposide, Cytarabine, and Melphalan), Busulfan/Melphalan, and Carmustine/Melphalan conditioning when compared with Melphalan showed favorable survival outcomes with manageable toxicities although we need to see data from randomized, multicenter studies. Posttransplant maintenance and consolidation can maximize the benefit of transplant by prolonging progression-free survival. Current B-cell maturation antigen CAR T-cell therapy showed remarkably high response rates, but didn't seem to provide durable response yet.

SUMMARY

Recent advances in myeloma therapy and autologous stem cell transplantation are described. Although we've seen many new developments including CAR T-cell therapies, autologous stem cell transplantation remains as the standard of care. However, it may be replaced by or combined with newer therapies in the future.

CAR-NK cell therapeutics for hematologic malignancies: hope is on the horizon

Chimeric antigen receptor (CAR)-T-cell therapy has achieved significant success in the treatment of hematologic malignancies. However, treatment-related toxicity and side effects remain the major drawbacks. As an important effector cell in innate immunity, natural killer (NK) cells exert strong antitumor functions and have better application prospects in the immunotherapy of hematologic malignancies. Compared with T cells, NK cells exhibit several advantages such as MHC-independent recognition. CAR-modified NK (CAR-NK) cells may exhibit a better ability of killing tumor cells. Herein, we review mainly preclinical data related to the development of CAR-NK cells in treating blood cancers.

Current status and hurdles for CAR-T cell immune therapy

Chimeric antigen receptor T (CAR-T) cells have emerged as novel and promising immune therapies for the treatment of multiple types of cancer in patients with hematological malignancies. There are several key components critical for development and application of CAR-T therapy. First, the design of CAR vectors can considerably affect several aspects of the physiological functions of these T cells. Moreover, despite the wide use of γ-retrovirus and lentivirus in mediating gene transfer into T cells, optimal CAR delivery systems are also being developed and evaluated. In addition, several classes of mouse models have been used to evaluate the efficacies of CAR-T cells; however, each model has its own limitations. Clinically, although surprising complete remission (CR) rates were observed in acute lymphoblastic leukemia (ALL), lymphoma, and multiple myeloma (MM), there is still a lack of specific targets for acute myeloid leukemia (AML). Leukemia relapse remains a major challenge, and its mechanism is presently under investigation. Cytokine release syndrome (CRS) and neurotoxicity are life-threatening adverse effects that need to be carefully treated. Several factors that compromise the activities of anti-solid cancer CAR-T cells have been recognized, and further improvements targeting these factors are the focus of the development of novel CAR-T cells. Overcoming the current hurdles will lead to optimal responses of CAR-T cells, thus paving the way for their wide clinical application.

Toward T Cell-Mediated Control or Elimination of HIV Reservoirs: Lessons From Cancer Immunology

As the AIDS epidemic unfolded, the appearance of opportunistic infections in at-risk persons provided clues to the underlying problem: a dramatic defect in cell-mediated immunity associated with infection and depletion of CD4⁺ T lymphocytes. Moreover, the emergence of HIV-associated malignancies in these same individuals was a clear indication of the significant role effective cellular immunity plays in combating cancers. As research in the HIV field progressed, advances included the first demonstration of the role of PD-1 in human T cell exhaustion, and the development of gene-modified T cell therapies, including chimeric antigen receptor (CAR) T cells. In the intervening years, the oncology field has capitalized on these advances, effectively mobilizing the cellular immune response to achieve immune-mediated remission or cure of previously intractable cancers. Although similar therapeutic advances have not yet been achieved in the HIV field, spontaneous CD8⁺ T cell mediated remission or functional cure of HIV infection does occur in very small subset of individuals in the absence of anti-retroviral therapy (ART). This has many similarities to the CD8⁺ T cell mediated functional control or elimination of cancers, and indicates that immunotherapy for HIV is a rational goal. In HIV infection, one major barrier to successful immunotherapy is the small, persistent population of infected CD4⁺ T cells, the viral reservoir, which evades pharmacological and immune-mediated clearance, and is largely maintained in secondary lymphoid tissues at sites where CD8⁺ T cells have limited access and/or function. The reservoir-enriched lymphoid microenvironment bears a striking resemblance to the tumor microenvironment of many solid tumors–namely high levels of anti-inflammatory cytokines, expression of co-inhibitory receptors, and physical exclusion of immune effector cells. Here, we review the parallels between CD8⁺ T cell-mediated immune control of HIV and cancer, and how advances in cancer immunotherapy may provide insights to direct the development of effective HIV cure strategies. Specifically, understanding the impact of the tissue microenvironment on T cell function and development of CAR T cells and therapeutic vaccines deserve robust attention on the path toward a CD8⁺ T cell mediated cure of HIV infection.

Industry updates from the field of stem cell research and regenerative medicine in May 2019

Latest developments in the field of stem cell research and regenerative medicine compiled from publicly available information and press releases from nonacademic institutions in May 2019.

Treatment of relapsed multiple myeloma: Evidence-based recommendations

The practice of choosing the next best therapy for patients with relapsed and/or refractory multiple myeloma (RRMM) is becoming increasingly complex. There is no clear consensus regarding the best treatment sequence for RRMM. With the approval of novel proteasome inhibitors (ixazomib and carfilzomib), immunomodulatory agents (pomalidomide), monoclonal antibodies (daratumumab and elotuzumab), and other targeted therapies, multiple combination regimens utilizing these agents are being studied with the goal of enhancing disease control, prolonging progression-free survival, and improving overall survival. We, herein, describe a review of FDA-approved regimens for RRMM patients and offer a paradigm in selecting subsequent treatment regimens, focusing on patient specific morbidity, treatment toxicity, and disease-specific characteristics.

The MYRACLE protocol study: a multicentric observational prospective cohort study of patients with multiple myeloma

Background

Despite recent advances in the treatment of multiple myeloma, the disease constantly relapses and is still considered as incurable. The current knowledge about the biological mechanisms underlying resistance to the different class of drugs in multiple myeloma remains poor. The primary objective of the MYRACLE (Myeloma Resistance And Clonal Evolution) cohort, a multicenter prospective cohort of patients with multiple myeloma, is to address this limitation. We here describe the study background, design and methods used for this cohort.

Methods/design

All patients (> 18 year old) diagnosed with de novo or relapsed multiple myeloma and treated in two hematology department from west of France are included in the MYRACLE cohort. Patients provide a signed informed to be included in the study. All subjects are followed until refusal to participate in the study or death. The MYRACLE cohort prospectively collects data on socio-economic status, medical status, imaging, prognosis factors, MM therapies and associated events (resistance, safety issues). Patients also complete standardized quality of life questionnaires. In addition, bone marrow samples will be collected at time of diagnosis and relapses to perform biomarkers analysis and functional assays exploring mechanisms underlying drug resistance.

Discussion

The “real-life” MYRACLE cohort offers the opportunity to prospectively collect epidemiological, medical, QoL and biological data from MM patients during the course of the disease (at time of diagnosis and subsequent relapses). At mid-tem, this integrative cohort will be unique at producing a large variety of data that can be used to conceive the most effective personalized therapy for MM patients. Additionally, the MYRACLE cohort will allow integrating the medical care of MM patients in a health and pharmacoeconomic perspective.

Cardiotoxicity of Immune Therapy

The advent of immunotherapy, particularly immune checkpoint inhibitors and chimeric antigen receptor T-cell therapy, has ushered in a promising new era of treatment of patients with a variety of malignancies who historically had a poor prognosis. However, these therapies are associated with potentially life-threatening cardiovascular adverse effects. As immunotherapy evolves to include a wider variety of malignancies, risk stratification, prompt recognition, and treatment of cardiotoxicity will become increasingly important and hence cardiologists will need to play a fundamental role in the comprehensive care of these patients. This article reviews cardiotoxicity associated with contemporary immunotherapy and discusses potential management strategies.

Relapsed refractory multiple myeloma: a comprehensive overview

Most patients with relapsed/refractory multiple myeloma (RRMM) have been treated with drug combinations including a proteasome inhibitor (PI) and/or an immunomodulatory drug (IMiD). The goal of therapy for such patients is therefore to achieve disease control with acceptable toxicity and patient-defined decent quality of life. Physicians face a difficult task not only deciding who to treat, but also when to treat and how to treat, utilizing knowledge of previously administered therapies, patient comorbidities, potential adverse events, and patient wishes to make such a critical decision. New drugs and combination regimens are continuously underway thus broadening the options for therapy and giving way to a more individualized approach for patients with RRMM. The integration of novel agents into the treatment paradigm has shifted the perception of multiple myeloma (MM) from an incurable, fatal disease to a manageable, chronic one. This comprehensive review addresses the results and challenges posed by many of the newer agents for the treatment of RRMM. It attempts to propose a universal strategy for optimal therapy decision-making thus answering three simple fundamental questions-when to treat, how to treat, and how long to treat for.

Chimeric antigen receptor T-cell therapy for multiple myeloma: a consensus statement from The European Myeloma Network

Adoptive cellular therapy using chimeric antigen receptor T-cell (CART) therapy is currently being evaluated in patients with relapsed / refractory multiple myeloma (MM). The majority of CAR-T cell programs now being tested in clinical trials are targeting B-cell maturation antigen. Several recent phase I / II trials show promising preliminary results in patients with MM progressing on proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies targeting CD38. CAR-T cell therapy is a potentially life-threatening strategy that can only be administered in experienced centers. For the moment, CAR-T cell therapy for MM is still experimental, but once this strategy has been approved in relapsed/refractory MM, it will become one of the most important indications for this therapy in Europe and world-wide. This manuscript proposes practical considerations for the use of CAR-T cell therapy in MM, and discusses several important issues for its future development.

Meeting report of the 7th Heidelberg Myeloma Workshop: today and tomorrow

PURPOSE

The 7th Heidelberg Myeloma Workshop was held on April 5th and 6th, 2019 at the University Hospital Heidelberg.

METHODS AND RESULTS

Main topics of the meeting were (1) diagnostics and prognostic factors, (2) role of immunotherapy in multiple myeloma (MM), (3) current therapy of MM, (4) biology and genomics of MM as well as (5) novel treatment concepts. A debate on the status of minimal residual disease (MRD) driven therapy was held.

CONCLUSION

Diagnostics and treatment of newly diagnosed and relapsed MM are continuously evolving. While advances in the field of (single cell) genetic analysis now allow for characterization of the disease at an unprecedented resolution, immunotherapeutic approaches and MRD testing are at the forefront of the current clinical trial landscape.

Challenges and opportunities in the assessment of measurable residual disease in multiple myeloma

Treatment response assessment in multiple myeloma (MM) relies on the detection of paraprotein in serum and/or urine, bone marrow morphology and immunohistochemistry. With remarkable advances in therapy, particularly in the newly diagnosed setting, achievement of complete remission became frequent, creating the need to identify smaller amounts of residual disease and understand their prognostic and therapeutic implications. Measurable residual disease (MRD) can be assessed primarily by flow cytometry and next generation sequencing and state-of-the-art assays have sensitivity approaching 1 in 10⁶ cells. This review discusses the existing challenges in utilizing MRD to inform management of MM and highlights open research questions and opportunities as MRD is more routinely incorporated into clinical practice for patients with MM.

Emerging protein kinase inhibitors for the treatment of multiple myeloma

Introduction: Significant advances have been made during the last two decades in terms of new therapeutic options but also of innovative approaches to diagnosis and management of multiple myeloma (MM). While patient survival has been significantly prolonged, most patients relapse. Including the milestone approval of the first kinase inhibitor imatinib mesylate for CML in 2001, 48 small molecule protein kinase (PK) inhibitors have entered clinical practice until now. However, no PK inhibitor has been approved for MM therapy yet. Areas covered: This review article summarizes up-to-date knowledge on the pathophysiologic role of PKs in MM. Derived small molecules targeting receptor tyrosine kinases (RTKs), the Ras/Raf/MEK/MAPK- pathway, the PI3K/Akt/mTOR- pathway as well as Bruton tyrosine kinase (BTK), Aurora kinases (AURK), and cyclin-dependent kinases (CDKs) are most promising. Preclinical as well as early clinical data focusing on these molecules will be presented and critically reviewed. Expert opinion: Current MM therapy is directed against general vulnerabilities. Novel therapeutic strategies, inhibition of PKs in particular, are directed to target tumor-specific driver aberrations such as genetic abnormalities and microenvironment-driven deregulations. Results of ongoing Precision Medicine trials with PK inhibitors alone or in combination with other agents are eagerly awaited and hold the promise of once more improving MM patient outcome.

Chimeric Antigen Receptor-Modified T Cell Therapy in Multiple Myeloma: Beyond B Cell Maturation Antigen

Chimeric antigen receptor (CAR)-modified T cell therapy is a rapidly emerging immunotherapeutic approach that is revolutionizing cancer treatment. The impressive clinical results obtained with CAR-T cell therapy in patients with acute lymphoblastic leukemia and lymphoma have fueled the development of CAR-T cells targeting other malignancies, including multiple myeloma (MM). The field of CAR-T cell therapy for MM is still in its infancy, but remains promising. To date, most studies have been performed with B cell maturation antigen (BCMA)-targeted CARs, for which high response rates have been obtained in early-phase clinical trials. However, responses are usually temporary, and relapses have frequently been observed. One of the major reasons for relapse is the loss or downregulation of BCMA expression following CAR-T therapy. This has fostered a search for alternative target antigens that are expressed on the MM cell surface. In this review, we provide an overview of myeloma target antigens other than BCMA that are currently being evaluated in pre-clinical and clinical studies.

B cell maturation antigen (BCMA)-based immunotherapy for multiple myeloma

Introduction: B cell maturation antigen (BCMA) contributes to MM pathophysiology and is a target antigen for novel MM immunotherapy. Complete responses have been observed in heavily pretreated MM patients after treatment with BCMA antibody-drug conjugates (ADC), chimeric antigen receptor T, and bi-specific T cell engagers (BiTE®). These and other innovative BCMA-targeted therapies transform the treatment landscape and patient outcome in MM. Areas covered: The immunobiological rationale for targeting BCMA in MM is followed by key preclinical studies and available clinical data on efficacy and safety of therapies targeting BCMA from recent phase I/II studies. Expert opinion: BCMA is the most selective MM target antigen, and BCMA-targeted approaches have achieved high responses even in relapse and refractory MM as a monotherapy. Long-term follow-up and correlative studies using immuno-phenotyping and -sequencing will delineate mechanisms of overcoming the immunosuppressive MM bone marrow microenvironment to mediate additive or synergistic anti-MM cytotoxicity. Moreover, they will delineate cellular and molecular events underlying the development of resistance underlying relapse of disease. Most importantly, targeted BCMA-based immunotherapies used earlier in the disease course and in combination (adoptive T cell therapy, mAbs/ADCs, checkpoint and cytokine blockade, and vaccines) have great promise to achieve long-term disease control and potential cure.

High-Risk Multiple Myeloma: Integrated Clinical and Omics Approach Dissects the Neoplastic Clone and the Tumor Microenvironment

Multiple myeloma (MM) is a genetically heterogeneous disease that includes a subgroup of 10–15% of patients facing dismal survival despite the most intensive treatment. Despite improvements in biological knowledge, MM is still an incurable neoplasia, and therapeutic options able to overcome the relapsing/refractory behavior represent an unmet clinical need. The aim of this review is to provide an integrated clinical and biological overview of high-risk MM, discussing novel therapeutic perspectives, targeting the neoplastic clone and its microenvironment. The dissection of the molecular determinants of the aggressive phenotypes and drug-resistance can foster a better tailored clinical management of the high-risk profile and therapy-refractoriness. Among the current clinical difficulties in MM, patients’ management by manipulating the tumor niche represents a major challenge. The angiogenesis and the stromal infiltrate constitute pivotal mechanisms of a mutual collaboration between MM and the non-tumoral counterpart. Immuno-modulatory and anti-angiogenic therapy hold great efficacy, but variable and unpredictable responses in high-risk MM. The comprehensive understanding of the genetic heterogeneity and MM high-risk ecosystem enforce a systematic bench-to-bedside approach. Here, we provide a broad outlook of novel druggable targets. We also summarize the existing multi-omics-based risk profiling tools, in order to better select candidates for dual immune/vasculogenesis targeting.

Bispecific T-Cell Redirection versus Chimeric Antigen Receptor (CAR)-T Cells as Approaches to Kill Cancer Cells

The concepts for T-cell redirecting bispecific antibodies (TRBAs) and chimeric antigen receptor (CAR)-T cells are both at least 30 years old but both platforms are just now coming into age. Two TRBAs and two CAR-T cell products have been approved by major regulatory agencies within the last ten years for the treatment of hematological cancers and an additional 53 TRBAs and 246 CAR cell constructs are in clinical trials today. Two major groups of TRBAs include small, short-half-life bispecific antibodies that include bispecific T-cell engagers (BiTE®s) which require continuous dosing and larger, mostly IgG-like bispecific antibodies with extended pharmacokinetics that can be dosed infrequently. Most CAR-T cells today are autologous, although significant strides are being made to develop off-the-shelf, allogeneic CAR-based products. CAR-Ts form a cytolytic synapse with target cells that is very different from the classical immune synapse both physically and mechanistically, whereas the TRBA-induced synapse is similar to the classic immune synapse. Both TRBAs and CAR-T cells are highly efficacious in clinical trials but both also present safety concerns, particularly with cytokine release syndrome and neurotoxicity. New formats and dosing paradigms for TRBAs and CAR-T cells are being developed in efforts to maximize efficacy and minimize toxicity, as well as to optimize use with both solid and hematologic tumors, both of which present significant challenges such as target heterogeneity and the immunosuppressive tumor microenvironment.

Immune checkpoint blockade and CAR-T cell therapy in hematologic malignancies

Harnessing the power of the immune system to recognize and eliminate cancer cells is a longtime exploration. In the past decade, monoclonal antibody (mAb)-based immune checkpoint blockade (ICB) and chimeric antigen receptor T (CAR-T) cell therapy have proven to be safe and effective in hematologic malignancies. Despite the unprecedented success of ICB and CAR-T therapy, only a subset of patients can benefit partially due to immune dysfunction and lack of appropriate targets. Here, we review the preclinical and clinical advances of CTLA-4 and PD-L1/PD-1-based ICB and CD19-specific CAR-T cell therapy in hematologic malignancies. We also discuss the basic research and ongoing clinical trials on emerging immune checkpoints (Galectin-9/Tim-3, CD70/CD27, LAG-3, and LILRBs) and on new targets for CAR-T cell therapy (CD22, CD33, CD123, BCMA, CD38, and CD138) for the treatment of hematologic malignancies.

Novel targets for the treatment of relapsing multiple myeloma

Introduction: Multiple myeloma (MM) is characterized by the high tendency to relapse and develop drug resistance. Areas covered: This review focused on the main novel targets identified to design drugs for the treatment of relapsing MM patients. CD38 and SLAMF7 are the main surface molecules leading to the development of monoclonal antibodies (mAbs) recently approved for the treatment of relapsing MM patients. B cell maturation antigen (BCMA) is a suitable target for antibody-drug conjugates, bispecific T cell engager mAbs and Chimeric Antigen Receptor (CAR)-T cells. Moreover, the programmed cell death protein 1 (PD)-1/PD-Ligand (PD-L1) expression profile by MM cells and their microenvironment and the use of immune checkpoints inhibitors in MM patients are reported. Finally, the role of histone deacetylase (HDAC), B cell lymphoma (BCL)-2 family proteins and the nuclear transport protein exportin 1 (XPO1) as novel targets are also underlined. The clinical results of the new inhibitors in relapsing MM patients are discussed. Expert opinion: CD38, SLAMF7, and BCMA are the main targets for different immunotherapeutic approaches. Selective inhibitors of HDAC6, BCL-2, and XPO1 are new promising compounds under clinical investigation in relapsing MM patients.