CARs in the Lead Against Multiple Myeloma

From spear to trident: Upgrading arsenal of CAR-T cells in the treatment of multiple myeloma

Multiple myeloma (MM), marked by abnormal proliferation of plasma cells and production of monoclonal immunoglobulin heavy or light chains in the majority of patients, has traditionally been associated with poor survival, despite improvements achieved in median survival in all age groups since the introduction of novel agents. Survival has significantly improved with the development of new drugs and new treatment options, such as chimeric antigen receptor T-cell therapy (CAR-T), which have shown promise and given new hope in MM therapy. CARs are now classified as first-, second-, and third-generation CARs based on the number of monovalent to trivalent co-stimulatory molecules incorporated into their design. The scope of this review was relatively narrow because it was mainly about a comparison of the literature on the clinical application of CAR-T therapy in MM. Thus, our goal is to provide an overview of the new advances of CAR-T cells in the cure of MM, so in this review we looked at the progress of the clinical use of CAR-T cells in MM to try to provide a reference for their clinical use when managing MM.

Current progress in chimeric antigen receptor-modified T cells for the treatment of metastatic breast cancer

Breast cancer is the leading cancer in women. Around 20-30% breast cancer patients undergo invasion or metastasis after radical surgical resection and eventually die. Number of breast cancer patients show poor sensitivity toward treatments despite the advances in chemotherapy, endocrine therapy, and molecular targeted treatments. Therapeutic resistance and tumor recurrence or metastasis develop with the ongoing treatments. Conducive treatment strategies are thus required. Chimeric antigen receptor (CAR)-modified T-cell therapy has progressed as a part of tumor immunotherapy. However, CAR-T treatment has not been effective in solid tumors because of tumor microenvironment complexity, inhibitory effects of extracellular matrix, and lacking ideal tumor antigens. Herein, the prospects of CAR-T cell therapy for metastatic breast cancer are discussed, and the targets for CAR-T therapy in breast cancer (HER-2, C-MET, MSLN, CEA, MUC1, ROR1, EGFR) at clinical level are reviewed. Moreover, solutions are proposed for the challenges of breast cancer CAR-T therapy regarding off-target effects, heterogeneous antigen expression by tumor cells and immunosuppressive tumor microenvironment. Ideas for improving the therapeutics of CAR-T cell therapy in metastatic breast cancer are suggested.

Broadly applicable TCR-based therapy for multiple myeloma targeting the immunoglobulin J chain

BACKGROUND

The immunoglobulin J chain (Jchain) is highly expressed in the majority of multiple myeloma (MM), and Jchain-derived peptides presented in HLA molecules may be suitable antigens for T-cell therapy of MM.

METHODS

Using immunopeptidomics, we identified Jchain-derived epitopes presented by MM cells, and pHLA tetramer technology was used to isolate Jchain-specific T-cell clones.

RESULTS

We identified T cells specific for Jchain peptides presented in HLA-A1, -A24, -A3, and -A11 that recognized and lysed JCHAIN-positive MM cells. TCRs of the most promising T-cell clones were sequenced, cloned into retroviral vectors, and transferred to CD8 T cells. Jchain TCR T cells recognized target cells when JCHAIN and the appropriate HLA restriction alleles were expressed, while JCHAIN or HLA-negative cells, including healthy subsets, were not recognized. Patient-derived JCHAIN-positive MM samples were also lysed by Jchain TCR T cells. In a preclinical in vivo model for established MM, Jchain-A1, -A24, -A3, and -A11 TCR T cells strongly eradicated MM cells, which resulted in 100-fold lower tumor burden in Jchain TCR versus control-treated mice.

CONCLUSIONS

We identified TCRs targeting Jchain-derived peptides presented in four common HLA alleles. All four TCRs demonstrated potent preclinical anti-myeloma activity, encouraging further preclinical testing and ultimately clinical development.

Chimeric antigen receptor T (CAR-T) cells: Novel cell therapy for hematological malignancies

Over the last decade, the emergence of several novel therapeutic approaches has changed the therapeutic perspective of human malignancies. Adoptive immunotherapy through chimeric antigen receptor T cell (CAR-T), which includes the engineering of T cells to recognize tumor-specific membrane antigens and, as a result, death of cancer cells, has created various clinical benefits for the treatment of several human malignancies. In particular, CAR-T-cell-based immunotherapy is known as a critical approach for the treatment of patients with hematological malignancies such as acute lymphoblastic leukemia (ALL), multiple myeloma (MM), chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML), Hodgkin lymphoma (HL), and non-Hodgkin's lymphoma (NHL). However, CAR-T-cell therapy of hematological malignancies is associated with various side effects. There are still extensive challenges in association with further progress of this therapeutic approach, from manufacturing and engineering issues to limitations of applications and serious toxicities. Therefore, further studies are required to enhance efficacy and minimize adverse events. In the current review, we summarize the development of CAR-T-cell-based immunotherapy and current clinical antitumor applications to treat hematological malignancies. Furthermore, we will mention the current advantages, disadvantages, challenges, and therapeutic limitations of CAR-T-cell therapy.

Ciltacabtagene autoleucel in patients with relapsed/refractory multiple myeloma: CARTITUDE-1 (phase 2) Japanese cohort

Chimeric antigen receptor (CAR) T cells targeting B-cell maturation antigen have shown positive responses in patients with multiple myeloma (MM). The phase 2 portion of the CARTITUDE-1 study of ciltacabtagene autoleucel (cilta-cel) included a cohort of Japanese patients with relapsed/refractory MM. Following a conditioning regimen of cyclophosphamide (300 mg/m² ) and fludarabine (30 mg/m² ), patients received a single cilta-cel infusion at a target dose of 0.75 × 10⁶ (range, 0.5-1.0 × 10⁶ CAR-positive viable T cells/kg). The primary endpoint was overall response rate (ORR; defined as partial response or better) by International Myeloma Working Group criteria. A key secondary endpoint was the rate of very good partial response (VGPR) or better (defined as VGPR, complete response, stringent complete response). This first analysis was performed at 6 months after the last patient received cilta-cel. Thirteen patients underwent apheresis, nine of whom received cilta-cel infusion. Eight patients who received cilta-cel at the target dose responded, yielding an ORR of 100%. Seven of eight (87.5%) patients achieved a VGPR or better. One additional patient who received a below-target dose of cilta-cel also achieved a best response of VGPR. MRD negativity (10^-5 threshold) was achieved in all six evaluable patients. Eight of nine (88.9%) patients who received cilta-cel infusion experienced a grade 3 or 4 adverse event, and eight (88.9%) patients experienced cytokine release syndrome (all grade 1 or 2). No CAR-T cell neurotoxicity was reported. A positive benefit/risk profile for cilta-cel was established for heavily pretreated Japanese patients with relapsed or refractory MM.

Engineering T-cells with chimeric antigen receptors to combat hematological cancers: an update on clinical trials

Chimeric antigen receptor (CAR) redirected T-cells has shown efficacy in the treatment of B-cell leukemia/lymphoma, however, high numbers of relapses occur due to loss of targeted antigen or intrinsic failure of the CAR T-cells. In this situation modifications of the basic strategy are envisaged to reduce the risk of relapse, some of them are in early clinical exploration. These include simultaneous targeting of multiple antigens or combination of CAR T-cell therapy with other treatment modalities such as checkpoint inhibitors. The review evaluates and discusses these modified advanced therapies and pre-clinical approaches with respect to their potential to control leukemia and lymphoma in the long-term.

Study on the Relationship Between the Expression of B Cell Mature Antigen and the Classification, Stage, and Prognostic Factors of Multiple Myeloma

The expression level of BCMA in bone marrow of 54 MM patients was detected in this study to explore the relationship between the BCMA expression and the classification, stage, and prognostic factors of MM. The BCMA expression level of the stable group and remission group was lower than that of the newly diagnosed group and relapse group (P=0.001). There was no significant difference in BCMA expression of MM patients in different types and stages (P>0.05), but it was found that for the newly diagnosed MM patients, the BCMA expression level of IgG patients was higher than that of IgA or light-chain patients (rank average 11.20 vs 5.44, P=0.014). There was no significant correlation between the BCMA expression and the age and serum creatinine of MM patients (P>0.05). And there was no significant difference in BCMA expression between patients with different levels of age and serum creatinine (P>0.05). But it was found that the BCMA expression level of the newly diagnosed MM patients was moderately positively correlated with their age (P=0.025, r=0.595). There was no significant correlation between the BCMA expression and serum β2-microglobulin, serum lactate dehydrogenase, free kap/lam ratio, and urine β2-microglobulin (P>0.05). But we found that the BCMA expression of patients with high serum β2-microglobulin was higher than that of patients with low serum β2-microglobulin (rank average 28.89 vs 17.54, P=0.017). And the BCMA expression of patients with abnormal serum free kap/lam ratio was higher than that of patients with normal ratio (rank average 28.49 vs 13.55, P=0.004). The BCMA expression was strongly positively correlated with 24-h urine protein, was moderately positively correlated with serum M protein and the percentage of plasma cells in bone marrow, was moderately negatively correlated with albumin and hemoglobin count, and was weakly positively correlated with serum corrected calcium (P<0.05). And it was found that the BCMA expression of positive serum immunofixation electrophoresis patients was higher than that of negative patients (rank average 29.94 vs 16.75, P=0.017). And we try to clarify the relationship between the bone marrow BCMA expression and the peripheral blood sBCMA expression. However, we have not found a clear correlation between them so far (P>0.05).

Cytokine Release Syndrome By T-cell-Redirecting Therapies: Can We Predict and Modulate Patient Risk?

T-cell-redirecting therapies are promising new therapeutic options in the field of cancer immunotherapy, but the development of these modalities is challenging. A commonly observed adverse event in patients treated with T-cell-redirecting therapies is cytokine release syndrome (CRS). Its clinical manifestation is a burden on patients, and continues to be a big hurdle in the clinical development of this class of therapeutics. We review different T-cell-redirecting therapies, discuss key factors related to cytokine release and potentially leading to CRS, and present clinical mitigation strategies applied for those modalities. We propose to dissect those risk factors into drug-target-disease-related factors and individual patient risk factors. Aiming to optimize the therapeutic intervention of these modalities, we illustrate how the knowledge on drug-target-disease-related factors, such as target expression, binding affinity, and target accessibility, can be leveraged in a model-based framework and highlight with case examples how modeling and simulation is applied to guide drug discovery and development. We draw attention to the current gaps in predicting the individual patient's risk towards a high-grade CRS, which requires further considerations of risk factors related, but not limited to, the patient's demographics, genetics, underlying pathologies, treatment history, and environmental exposures. The drug-target-disease-related factors together with the individual patient's risk factors can be regarded as the patient's propensity for developing CRS in response to therapy. As an outlook, we suggest implementing a risk scoring system combined with mechanistic modeling to enable the prediction of an individual patient's risk of CRS for a given therapeutic intervention.

Prognostic impact of resistance to bortezomib and/or lenalidomide in carfilzomib-based therapies for relapsed/refractory multiple myeloma: The Kyoto Clinical Hematology Study Group, multicenter, pilot, prospective, observational study in Asian patients

Background

Combinatory strategies with carfilzomib (CFZ), a second‐generation proteasome inhibitor, plus dexamethasone (DEX) with or without lenalidomide (LEN) have shown promising efficacy for patients with relapsed/refractory multiple myeloma (RRMM) in pivotal clinical trials. However, their effects on patients who were resistance to bortezomib (BTZ) and/or LEN have not been fully evaluated in a daily practice setting.

Aims

To evaluate the real‐world efficacy and safety of CFZ‐based treatments; that is, CFZ with LEN plus DEX (KRD therapy) and CFZ with DEX (KD therapy), in Asian patients, we conducted a multicenter pilot prospective observational study in the Kyoto Clinical Hematology Study Group.

Methods and Results

All 50 patients with RRMM enrolled in this study were treated with CFZ‐based treatments between 2017 and 2019. KRD and KD were administered to 31 and 19 patients, respectively. The overall response rates (ORRs) were 80.6% with KRD and 73.7% with KD. Two‐year progression‐free survival (PFS) and overall survival (OS) were 58.5% and 79.7% with KRD, and 23.1% and 52.6% with KD. By multivariate analysis, refractoriness to BTZ and to LEN were identified as independent unfavorable factors for both PFS and OS. The common non‐hematologic AEs included hypertension (42.0%), fever (24.0%), fatigue (24.0%), and infection (16.0%). No serious heart failure was observed. This study is registered as UMIN000025108.

Conclusion

This study suggests the need of the development of novel CFZ‐containing strategy which can overcome the refractoriness to BTZ and/or LEN, while both KRD and KD were shown to be mostly feasible in Asian patients in a daily practice setting.

CAR T-cell therapy in multiple myeloma: more room for improvement

The emergence of various novel therapies over the last decade has changed the therapeutic landscape for multiple myeloma. While the clinical outcomes have improved significantly, the disease remains incurable, typically in patients with relapsed and refractory disease. Chimeric antigen receptor (CAR) T-cell therapies have achieved remarkable clinical success in B-cell malignancies. This scope of research has more recently been extended to the field of myeloma. While B-cell maturation antigen (BCMA) is currently the most well-studied CAR T antigen target in this disease, many other antigens are also undergoing intensive investigations. Some studies have shown encouraging results, whereas some others have demonstrated unfavorable results due to reasons such as toxicity and lack of clinical efficacy. Herein, we provide an overview of CAR T-cell therapies in myeloma, highlighted what has been achieved over the past decade, including the latest updates from ASH 2020 and discussed some of the challenges faced. Considering the current hits and misses of CAR T therapies, we provide a comprehensive analysis on the current manufacturing technologies, and deliberate on the future of CAR T-cell domain in MM.

Adoptive Cellular Therapy for Solid Tumors

Cancer immunotherapy tools include antibodies, vaccines, cytokines, oncolytic viruses, bispecific molecules, and cellular therapies. This review will focus on adoptive cellular therapy, which involves the isolation of a patient's own immune cells followed by their ex vivo expansion and reinfusion. The majority of adoptive cellular therapy strategies utilize T cells isolated from tumor or peripheral blood, but may utilize other immune cell subsets. T-cell therapies in the form of tumor-infiltrating lymphocytes, T-cell receptor T cells, and CAR T cells may act as "living drugs" as these infused cells expand, engraft, and persist in vivo, allowing adaptability over time and enabling durable remissions in subsets of patients. Adoptive cellular therapy has been less successful in the management of solid tumors because of poor homing, proliferation, and survival of transferred cells. Strategies are discussed, including expression of transgenes to address these hurdles. Additionally, advances in gene editing using CRISPR/Cas9 and similar technologies are described, which allow for clinically translatable gene-editing strategies to enhance the antitumor activity and to surmount the hostilities advanced by the host and the tumor. Finally, the common toxicities and approaches to mitigate these are reviewed.

Nanoparticle T-cell engagers as a modular platform for cancer immunotherapy

T-cell-based immunotherapy, such as CAR-T cells and bispecific T-cell engagers (BiTEs), has shown promising clinical outcomes in many cancers; however, these therapies have significant limitations, such as poor pharmacokinetics and the ability to target only one antigen on the cancer cells. In multiclonal diseases, these therapies confer the development of antigen-less clones, causing tumor escape and relapse. In this study, we developed nanoparticle-based bispecific T-cell engagers (nanoBiTEs), which are liposomes decorated with anti-CD3 monoclonal antibodies (mAbs) targeting T cells, and mAbs targeting the cancer antigen. We also developed a nanoparticle that targets multiple cancer antigens by conjugating multiple mAbs against multiple cancer antigens for T-cell engagement (nanoMuTEs). NanoBiTEs and nanoMuTEs have a long half-life of about 60 h, which enables once-a-week administration instead of continuous infusion, while maintaining efficacy in vitro and in vivo. NanoMuTEs targeting multiple cancer antigens showed greater efficacy in myeloma cells in vitro and in vivo, compared to nanoBiTEs targeting only one cancer antigen. Unlike nanoBiTEs, treatment with nanoMuTEs did not cause downregulation (or loss) of a single antigen, and prevented the development of antigen-less tumor escape. Our nanoparticle-based immuno-engaging technology provides a solution for the major limitations of current immunotherapy technologies.

Potent Activity of an Anti-ICAM1 Antibody-Drug Conjugate against Multiple Myeloma

PURPOSE

New therapies have changed the outlook for patients with multiple myeloma, but novel agents are needed for patients who are refractory or relapsed on currently approved drug classes. Novel targets other than CD38 and BCMA are needed for new immunotherapy development, as resistance to daratumumab and emerging anti-BCMA approaches appears inevitable. One potential target of interest in myeloma is ICAM1. Naked anti-ICAM1 antibodies were active in preclinical models of myeloma and safe in patients, but showed limited clinical efficacy. Here, we sought to achieve improved targeting of multiple myeloma with an anti-ICAM1 antibody-drug conjugate (ADC).

EXPERIMENTAL DESIGN

Our anti-ICAM1 human mAb was conjugated to an auristatin derivative, and tested against multiple myeloma cell lines in vitro, orthotopic xenografts in vivo, and patient samples ex vivo. The expression of ICAM1 was also measured by quantitative flow cytometry in patients spanning from diagnosis to the daratumumab-refractory state.

RESULTS

The anti-ICAM1 ADC displayed potent anti-myeloma cytotoxicity in vitro and in vivo. In addition, we have verified that ICAM1 is highly expressed on myeloma cells and shown that its expression is further accentuated by the presence of bone marrow microenvironmental factors. In primary samples, ICAM1 is differentially overexpressed on multiple myeloma cells compared with normal cells, including daratumumab-refractory patients with decreased CD38. In addition, ICAM1-ADC showed selective cytotoxicity in multiple myeloma primary samples.

CONCLUSIONS

We propose that anti-ICAM1 ADC should be further studied for toxicity, and if safe, tested for clinical efficacy in patients with relapsed or refractory multiple myeloma.

Overview of anti-BCMA CAR-T immunotherapy for multiple myeloma and relapsed/refractory multiple myeloma

Multiple myeloma (MM) is a haematological malignancy caused by malignant proliferation of plasma cells in bone marrow. In recent years, MM patients are commonly treated with chemotherapy, autologous stem cell transplantation, protease inhibitors, immunomodulatory drugs and monoclonal antibodies, however most patients eventually relapse. Therefore, more effective therapies are highly needed. Anti-BCMA CAR-T therapy, a novel and efficacious method for treating MM and relapsed/refractory multiple myeloma (RRMM), has been designed and applied in clinics. The CAR-T can specifically recognize the targeted molecule B cell maturation antigen (BCMA) and kill MM cells expressing BCMA and several clinical trials have revealed high response rates in the therapy. Herein, we summarize the developments, the current design and clinical trials, the side effects of anti-BCMA CAR-T therapy and comparison of it with other CAR-T therapies.

Emerging CAR landscape for cancer immunotherapy

In the last decade, there has been great advancement in manipulating the immune system or the cells of the immune system to bring about effective therapies. While harnessing the immune system against cancer is not a new concept, successful reprograming with T cells with chimeric antigen receptor (CAR) forming CAR-T cell therapy has revolutionized the treatment landscape for patients with refractory, high-grade B cell malignancies. The journey from proof-of-concept to FDA-approved commercial CAR-T products has taken almost 3 decades and untold amount of efforts, resources and manpower. With the success of CD19 CAR adoptive cellular immunotherapy leading the charge, CARs targeting various malignancies are in various stages of active development, racing towards regulatory approval, and raising hopes of further breakthroughs in cancer treatment options. In this review we will highlight recent clinical developments of the B cell maturation antigen (BCMA) CAR-T therapy for multiple myeloma (MM) to showcase how innovative CAR designs, coupled with careful selection of tumor-associated antigens, used in combination with other therapeutic agents, could help overcome some of the current limitations experienced in CAR-T immunotherapy. More patients could benefit from novel upfront cell therapy trials, that when combined with the current established induction regimens could have the potential to recondition and alter tumor environments, help restore somnolent anti-tumor immunity, and induce more effective and durable remissions.

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.

Current Perspectives in Cancer Immunotherapy

Different immunotherapeutic approaches have proved to be of significant clinical value to many patients with different types of advanced cancer. However, we need more precise immunotherapies and predictive biomarkers to increase the successful response rates. The advent of next generation sequencing technologies and their applications in immuno-oncology has helped us tremendously towards this aim. We are now moving towards the realization of personalized medicine, thus, significantly increasing our expectations for a more successful management of the disease. Here, we discuss the current immunotherapeutic approaches against cancer, including immune checkpoint blockade with an emphasis on anti-PD-L1 and anti-CTLA-4 monoclonal antibodies. We also analyze a growing list of other co-inhibitory and co-stimulatory markers and emphasize the mechanism of action of the principal pathway for each of these, as well as on drugs that either have been FDA-approved or are under clinical investigation. We further discuss recent advances in other immunotherapies, including cytokine therapy, adoptive cell transfer therapy and therapeutic vaccines. We finally discuss the modulation of gut microbiota composition and response to immunotherapy, as well as how tumor-intrinsic factors and immunological processes influence the mutational and epigenetic landscape of progressing tumors and response to immunotherapy but also how immunotherapeutic intervention influences the landscape of cancer neoepitopes and tumor immunoediting.

Synergistic combination of oncolytic virotherapy with CAR T-cell therapy

For patients with advanced hematological malignancies the therapeutic landscape has been transformed by the emergence of adoptive cell transfer utilizing autologous chimeric antigen receptor (CAR)-redirected T-cells. However, solid tumors have proved far more resistant to this approach. Here, we summarize the numerous challenges faced by CAR T-cells designed to target solid tumors, highlighting, in particular, issues related to impaired trafficking, expansion, and persistence. In parallel, we draw attention to exciting developments in the burgeoning field of oncolytic virotherapy and posit strategies for the synergistic combination of oncolytic viruses with CAR T-cells to improve outcomes for patients with advanced solid tumors.

Emerging immune targets for the treatment of multiple myeloma

We reviewed emerging immune strategies for multiple myeloma (MM) therapy excluding US FDA approved drugs. In relapsed refractory MM, isatuximab (anti-CD38) monotherapy achieved overall response (OR) of 24%. Other monoclonal antibodies that have shown efficacy in combination therapy include siltuximab (OR: 66%), indatuximab (OR: 78%), isatuximab (OR: 64.5%), pembrolizumab (OR: 60%), bevacizumab (OR: 70%), dacetuzumab (OR: 39%) and lorvotuzumab (OR: 56.4%). No OR was observed with monotherapy using BI-505, siltuximab, bevacizumab, AVE-1642, figitumumab, atacicept, milatuzumab, dacetuzumab, lucatumumab, IPH2101, lorvotuzumab, BT062 and nivolumab. We included seven clinical trials on chimeric antigen receptor (CAR) T cells. CAR T-cell targets include BCMA, CD19, KLC and CD138. A recent experience of CAR T-cell (B-cell maturation antigen) therapy in advanced MM has shown global response of 100%. The future of monoclonal antibodies and adoptive T cells for MM treatment seems promising.

An introduction to chimeric antigen receptor (CAR) T-cell immunotherapy for human cancer

Chimeric antigen receptor (CAR) T-cell therapy represents a major advancement in personalized cancer treatment. In this strategy, a patient's own T cells are genetically engineered to express a synthetic receptor that binds a tumor antigen. CAR T cells are then expanded for clinical use and infused back into the patient's body to attack and destroy chemotherapy-resistant cancer. Dramatic clinical responses and high rates of complete remission have been observed in the setting of CAR T-cell therapy of B-cell malignancies. This resulted in two recent FDA approvals of CAR T cells directed against the CD19 protein for treatment of acute lymphoblastic leukemia and diffuse large B-cell lymphoma. Thus, CAR T cells are arguably one of the first successful examples of synthetic biology and personalized cellular cancer therapy to become commercially available. In this review, we introduce the concept of using CAR T cells to break immunological tolerance to tumors, highlight several challenges in the field, discuss the utility of biomarkers in the context of predicting clinical responses, and offer prospects for developing next-generation CAR T cell-based approaches that will improve outcome.

Chimeric antigen receptor T cell targeting B cell maturation antigen immunotherapy is promising for multiple myeloma

Multiple myeloma (MM) remains an incurable plasma cells malignancy because of its complex genetic heterogeneity and high relapse rate post immunotherapy. The encouraging results of chimeric antigen receptor T cell (CAR-T) targeting B cell maturation antigen (BCMA) immunotherapy clinical trials have shed light on curing MM in recent years. However, many therapeutic side effects limit the promotion and clinical use of this novel effective approach such as cytokine release syndrome, antigen escape, and neurotoxicity. We should make every effort to do further study about this immunotherapy to make it safer and effective. This review focusing on this topic clarifies the following contents: present status of MM treatment, effectiveness of CAR-T cells, features of BCMA, preclinical and clinical trials of BCMA CAR-T cells therapy, and existing problems and strategies. Hoping to provide a reference for the subsequent correlative clinical and research.

CAR T Cell Therapy of Non-hematopoietic Malignancies: Detours on the Road to Clinical Success

Chimeric antigen receptor (CAR)-engineered T cells represent a breakthrough in personalized medicine. In this strategy, a patient's own T lymphocytes are genetically reprogrammed to encode a synthetic receptor that binds a tumor antigen, allowing T cells to recognize and kill antigen-expressing cancer cells. As a result of complete and durable responses in individuals who are refractory to standard of care therapy, CAR T cells directed against the CD19 protein have been granted United States Food and Drug Administration (FDA) approval as a therapy for treatment of pediatric and young adult acute lymphoblastic leukemia and diffuse large B cell lymphoma. Human trials of CAR T cells targeting CD19 or B cell maturation antigen in multiple myeloma have also reported early successes. However, a clear and consistently reproducible demonstration of the clinical efficacy of CAR T cells in the setting of solid tumors has not been reported to date. Here, we review the history and status of CAR T cell therapy for solid tumors, potential T cell-intrinsic determinants of response and resistance as well as extrinsic obstacles to the success of this approach for much more prevalent non-hematopoietic malignancies. In addition, we summarize recent strategies and innovations that aim to augment the potency of CAR T cells in the face of multiple immunosuppressive barriers operative within the solid tumor microenvironment. Advances in the field of CAR T cell biology over the coming years in the areas of safety, reliability and efficacy against non-hematopoietic cancers will ultimately determine how transformative adoptive T cell therapy will be in the broader battle against cancer.

Entering the Modern Era of Gene Therapy

Gene therapies are gaining momentum as promising early successes in clinical studies accumulate and examples of regulatory approval for licensing increase. Investigators are advancing with cautious optimism that effective, durable, and safe therapies will provide benefit to patients-not only those with single-gene disorders but those with complex acquired diseases as well. While the strategies being translated from the lab to the clinic are numerous, this review focuses on the clinical research that has forged the gene therapy field as it currently stands.

Anti-Multiple Myeloma Activity of Nanobody-Based Anti-CD38 Chimeric Antigen Receptor T Cells

Chimeric antigen receptor T cells (CAR-Ts) are a promising strategy for the treatment of many cancers, including multiple myeloma (MM), a hematological malignancy characterized by the high expression of CD38. To broaden the applications of using CD38 as a therapeutic target for the disease, we developed a new nanobody against CD38 and constructed a CD38-CAR that was composed of this nanobody as the targeting domain, and 4-1BB and CD3ζ as the costimulatory and activating domains, in a lentiviral vector. CD3⁺ T cells from healthy individuals were transduced with the CD38-CAR at an efficiency higher than 60%, as determined by CD38-CAR expression using flow cytometry. The CD38-CAR-Ts proliferated efficiently and produced more inflammatory cytokines, such as IL-2, IFN-γ, and TNF-α, when activated. The CD38-CAR-Ts effectively lysed CD38⁺ MM cell lines, including LP-1, RPMI 8226, OPM2, and MOLP8, and primary MM cells from multiple myeloma patients. The specificity was demonstrated by the fact that CD38-CAR-Ts showed little cytotoxicity on LP-1 cells with CD38 knocked out or on K562 cells, which do not express CD38. CD38-CAR-Ts appeared to have a very slight cytotoxicity against CD38⁺ fractions of T cells, B cells, and natural killer cells. In addition, the lysis of CD34⁺ hematopoietic progenitor cells did not completely inhibit the development of colony-forming units. In vivo, CD38-CAR-Ts inhibited tumor growth in NOD/SCID mice that were subcutaneously inoculated with RPMI 8226 cells. These results demonstrate that the CD38-CAR-Ts constructed with the anti-CD38 nanobody are a promising approach for the treatment of multiple myeloma.

Building upon the success of CART19: chimeric antigen receptor T cells for hematologic malignancies

Chimeric antigen receptor T cell (CART) therapy has dramatically changed the therapeutic prospects for B cell malignancies. Over the last decade CD19-redirected CART have demonstrated the ability to induce deep, long-lasting remissions and possibly cure patients with relapsing B cell neoplasms. Such impressive results with CART19 fostered efforts to expand this technology to other incurable malignancies that naturally do not express CD19, such as acute myeloid leukemia (AML), Hodgkin lymphoma (HL) and multiple myeloma (MM). However, to reach this goal, several hurdles have to be overcome, in particular: (i) the apparent lack of suitable targets as effective as CD19; (ii) the immunosuppressive tumor microenvironment; (iii) intra-tumoral heterogeneity and antigen-negative relapses. Therefore, new strategies that allow safer and more potent CART platforms are under development and may provide grounds for new exciting breakthroughs in the field.

The application of CAR-T cell therapy in hematological malignancies: advantages and challenges

Chimeric antigen receptor T cell (CAR-T cell) therapy is a novel adoptive immunotherapy where T lymphocytes are engineered with synthetic receptors known as chimeric antigen receptors (CAR). The CAR-T cell is an effector T cell that recognizes and eliminates specific cancer cells, independent of major histocompatibility complex molecules. The whole procedure of CAR-T cell production is not well understood. The CAR-T cell has been used predominantly in the treatment of hematological malignancies, including acute lymphoblastic leukemia, chronic lymphocytic leukemia, lymphoma, and multiple myeloma. Solid tumors including melanoma, breast cancer and sarcoma offer great promise in CAR-T cell research and development. CD19 CAR-T cell is most commonly used, and other targets, including CD20, CD30, CD38 and CD138 are being studied. Although this novel therapy is promising, there are several disadvantages. In this review we discuss the applications of CAR-T cells in different hematological malignancies, and pave a way for future improvement on the effectiveness and persistence of these adoptive cell therapies.

Engineering chimeric antigen receptor-T cells for cancer treatment

Intratumor heterogeneity of tumor clones and an immunosuppressive microenvironment in cancer ecosystems contribute to inherent difficulties for tumor treatment. Recently, chimeric antigen receptor (CAR) T-cell therapy has been successfully applied in the treatment of B-cell malignancies, underscoring its great potential in antitumor therapy. However, functional challenges of CAR-T cell therapy, especially in solid tumors, remain. Here, we describe cancer-immunity phenotypes from a clonal-stromal-immune perspective and elucidate mechanisms of T-cell exhaustion that contribute to tumor immune evasion. Then we assess the functional challenges of CAR-T cell therapy, including cell trafficking and infiltration, targeted-recognition and killing of tumor cells, T-cell proliferation and persistence, immunosuppressive microenvironment and self-control regulation. Finally, we delineate tumor precision informatics and advancements in engineered CAR-T cells to counteract inherent challenges of the CAR-T cell therapy, either alone or in combination with traditional therapeutics, and highlight the therapeutic potential of this approach in future tumor precision treatment.

Current developments in immunotherapy in the treatment of multiple myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy and represents approximately 10% of all hematological neoplasms. Standard therapy consists of induction therapy followed by high-dose chemotherapy and autologous stem cell transplantation (ASCT) or, if ASCT cannot be performed, standard doublet, triplet, or quadruplet, novel agent-containing induction treatment until progression. Although MM is still regarded as mostly incurable by current standards, the development of several novel compounds, combination therapies, and immunotherapy approaches has raised great hopes about transforming MM into an indolent, chronic disease and possibly achieving a cure for individual patients. Several new inhibitory and immunological agents have been approved or are under intensive investigation and may lead to new therapeutic options for patients with relapsed/refractory MM, for patients ineligible for ASCT, and for patients after ASCT. Especially in the field of immunotherapy, including monoclonal antibodies, checkpoint inhibition, and chimeric antigen receptor T cells, current advances are rapid and highly promising. This review aims to summarize the newest and most promising immunotherapeutic agents for MM, their clinical efficacy, their adverse event (AE) profiles, and the ways in which these AEs can best be overcome or avoided. Cancer 2018;124:2075-85. © 2018 American Cancer Society.