Chimeric antigen receptor T cell immunotherapy for multiple myeloma: A review of current data and potential clinical applications

Multiple myeloma (MM) is a malignant plasma cell disorder that remains incurable for most patients despite significant improvements achieved with modern therapy. Tumor evasion is a key process in the pathogenesis of MM and a compromised immune system is associated with more aggressive forms of the disease. In contrast, the emergence of myeloma-specific immune responses after both autologous and allogeneic stem cell transplantation is associated with better prognosis. Adoptive T cell therapies may improve specific anti-myeloma immunity resulting in long-lasting remissions. CAR T cell therapies for MM are at an early stage of clinical development. To date, anti-BCMA CAR T cells have shown the greatest results in early-phase clinical trials. Toxicities have included cytokine release syndrome (CRS) and neurotoxicity. Current areas of research in CAR T cell therapies include the use of gene-editing to enhance their effectiveness and safety, the integration of CAR T cells with other therapies (immunomodulatory drugs, checkpoint inhibitors) and CAR T cells to target multiple antigens.     

CAR T and CAR NK cells in multiple myeloma: Expanding the targets

Multiple myeloma (MM) is a haematologic malignancy with significant improvements in the overall survival over the last decade. However, patients still relapse and die due to a lack of treatment options. Ultimately, novel therapies with the potential for long term remissions are needed for patients with advanced MM. Research efforts for such immune therapies were not successful until recently when the first immunotherapies for MM were approved in 2015 and many more are under development. In this review, we focus on adoptive cell therapies including CAR T-cell and CAR NK-cell therapies for patients with MM. We will provide an update on clinical and translational advances with a focus on results from ongoing clinical trials with BCMA targeted cellular therapies and the development of other novel targets, changes in the manufacturing process, trials focusing on earlier lines of therapy and combinations with other therapies as well as off the shelf products.     

Clinical experience of CAR T cells for multiple myeloma

Important advances in the treatment landscape of multiple myeloma (MM) had been seen over the past two decades leading to improved overall survival but despite the progress multiple myeloma is still considered incurable and the prognosis of the pentarefractory patients have been poor. The development of immunotherapy and in particular adoptive cell therapy with chimeric antigen receptor (CAR) T cells have dramatically improved the outcomes of heavily pretreated relapsed/refractory MM patients. The bulk of CAR T-cell constructs currently in clinical development target the B-cell maturation antigen (BCMA) and to date only idecabtagene vicleucel (ide-cel) is approved by the Food and Drug Administration (FDA) for commercial use in adult patients with relapsed or refractory MM based on the promising clinical responses and positive safety record shown in the pivotal KarMMa study. This review focus on the development of CAR T-cell therapy for multiple myeloma as well as a brief review of the mechanisms of resistance, toxicity and new approaches under development.     

Severe persistent neurotoxicity associated with CAR T therapy in children

CD19-directed chimeric antigen receptor (CAR) T-cell therapy is an important therapy for relapsed or refractory acute lymphoblastic leukaemia, but its use carries the risk of immune effector cell-associated neurotoxicity syndrome (ICANS). In children, severe ICANS is almost universally reported in association with cytokine release syndrome and is reversible. We describe two cases of severe, intractable neurotoxicity following CAR T-cell therapy in children with pre-existing central nervous system (CNS) vulnerabilities. The cases were atypical in their delayed onset and independence from cytokine release syndrome and did not respond to standard therapies.     

Chimeric antigen receptor T cells (CAR-T) for the treatment of T-cell malignancies

At present, the only curative therapy for patients with T-cell malignancies is allogeneic stem cell transplant, which has associated risks and toxicities. Novel agents have been tried in relapsed T-cell acute lymphoblastic leukemia (T-ALL), but only one, with 20%–30% complete remission rates, has been approved by the US Food and Drug Administration. T-ALL is a heterogeneous disease, but it has universal overexpression of CD7 as well as several other T-cell markers, such as CD2 and CD5. T cells engineered to express a chimeric antigen receptor (CAR) are a promising cancer immunotherapy. Such targeted therapies have shown great potential for inducing both remissions and even long-term relapse-free survival in patients with B-cell leukemia and lymphoma. UCART7 for CD7⁺ T-cell malignancies is in development for treatment of relapsed T-ALL in children and adults. It may also have potential in other CD7⁺ hematologic malignancies that lack both effective therapies and targeted therapies. The challenges encountered and progress made in developing a novel fratricide-resistant “off-the-shelf” CAR-T (or UCART7) that targets CD7⁺ T-cell malignancies are discussed here.     

Enabling CAR T-cell therapies for HIV-positive lymphoma patients – A call for action

People living with HIV have a higher risk of developing lymphoma. Outcomes for people living with HIV with relapsed or refractory (r/r) lymphoma remain poor. For this group of patients, chimeric antigen receptor (CAR) T-cell therapy represents a new successful treatment strategy. However, people living with HIV were not included in pivotal trials, so data are limited to case reports. We searched the PubMed and Ovid technologies databases for literature until 1 November 2022 using the terms ‘HIV and CAR-T’, ‘HIV and lymphoma’ and ‘HIV and CAR-T and lymphoma’. Six cases with sufficient information were included in the review. The mean CD4⁺ T-cell count before CAR T-cell therapy was 221 cells/μL (range 52–629). The viral load was below the limit of detection in four patients. All patients had diffuse large B-cell lymphoma (DLBCL) and were treated with gamma-retroviral-based axicabtagene ciloleucel. Four patients developed cytokine-release syndrome (CRS) grade 2 or less or immune effector-cell-associated neurotoxicity syndrome (ICANs) grade 3–4. Four of six patients responded to CAR T-cell therapy (three complete remissions, one partial remission). In summary, there are no clinical reasons to restrict the use of CAR T-cell therapy in people living with HIV with r/r DLBCL. According to the current data, CAR T-cell therapy was safe and effective. In people who meet the standard criteria for CAR T-cell therapy, this treatment approach could significantly improve the unmet need for more effective treatment options for people living with HIV with r/r lymphoma.     

Chimeric antigen receptor T-cells: Properties,production, and quality control

Chimeric antigen receptor (CAR) T-cell therapy is a novel adoptive T-cell immunotherapy for haematological malignancies. First introduced into clinical practice in 2017, CAR T-cell therapy is now finding its place in the management of lymphoid malignancies, primarily of B-cell lineage, including lymphoblastic leukaemia, non-Hodgkin lymphoma and plasma cell myeloma, with remarkable therapeutic outcomes. CAR T-cells are a customised therapeutic product for each patient. Manufacture commences with collection of autologous T-cells, which are then genetically engineered ex vivo to express transmembrane CARs. These chimeric proteins consist of an antibody-like extracellular antigen-binding domain, to recognise specific antigens on the surface of tumour cells (e.g. CD19), linked to the intracellular co-stimulatory signalling domains of a T-cell receptor (e.g. CD137). The latter is required for in vivo CAR T-cell proliferation, survival, and durable efficacy. Following reinfusion, CAR T-cells harness the cytotoxic capacity of a patient's immune system. They overcome major mechanisms of tumour immuno-evasion and have potential to generate robust cytotoxic anti-tumour responses. This review discusses the background to CAR T-cell therapies, including their molecular design, mechanisms of action, methods of production, clinical applications and established and emerging technologies for CAR T-cell evaluation. It highlights the need for standardisation, quality control and monitoring of CAR T-cell therapies, to ensure their safety and efficacy in clinical management.     

The promise of CAR T-cell therapy in aggressive B-cell lymphoma

Relapsed or refractory aggressive B-cell lymphoma has an extremely poor prognosis and efforts to develop novel therapies for these patients have failed for almost four decades until the advent of chimeric antigen receptor (CAR) T-cell therapy. Within the last one year, two anti-CD19 CAR T-cell therapy products, axicabtagene ciloleucel and tisagenlecleucel, were approved by the United States Food and Drug Administration for the treatment of relapsed or refractory large B-cell lymphoma after at least two lines of systemic therapy based on multicenter single-arm phase two clinical trials. Here, we will discuss the different components of the CAR construct and their mechanisms of action, the role of conditioning chemotherapy, the efficacy and toxicity observed with anti-CD19 CAR T-cell therapies in aggressive B-cell lymphomas, and emerging strategies to further improve the safety and efficacy of these highly promising approaches.     

Toxicities associated with immunotherapies for hematologic malignancies

Immunotherapy has generated tremendous hope for patients with cancer that is refractory to standard approaches. Hematologic malignancies have taken the lead in harnessing the most recent advances in cell-based immunotherapies, such as CAR T cells, and some patients have achieved durable remissions. However, these T-cell-engaging therapies are associated with a new set of toxicities which need to be managed by caretakers, oncologists, nurses, and healthcare staff. In this review we provide an overview of the toxicity of some of these revolutionary agents including bispecific T cell engagers, checkpoint inhibitors, chimeric antigen receptor T-cells.     

CD33 directed bispecific antibodies in acute myeloid leukemia

Despite the approval of a number of new targeted therapies for acute myeloid leukemia (AML), median overall survival still remains poor, ranging from 12 to 18 months in most patients. Based on the success of blinatumomab, the CD19-targeted bispecific antibody for the treatment of acute lymphoblastic leukemia, the development of several CD33-targeted bispecific antibodies for AML are being investigated in clinical trials. In this review article of CD33-targeted bispecific antibodies, we describe the rationale for targeting CD3 x CD33, summarize the data from four ongoing phase 1 studies, review the major toxicity associated with CD33-targeted bispecific antibody therapy of cytokine release syndrome (CRS) and steps to mitigate CRS, and describe possible mechanisms of resistance to CD33-targeted bispecific antibody therapy. Future development to try to improve outcomes include combination therapies to reduce the tumor burden prior to starting treatment, combining with immune checkpoint inhibition therapy such as anti-PD-1/PDL1 antibodies, and the use of second generation bispecific antibodies that target two different antigens and recruit other effector cells such as nature killer cells and macrophages.     

Cellular and humoral immunotherapy in children,adolescents and young adults with non-Hodgkin lymphoma

The prognosis is dismal (2-year overall survival less than 25%) for childhood, adolescent, and young adult (CAYA) with relapsed and/or refractory (R/R) non-Hodgkin lymphoma (NHL). Novel targeted therapies are desperately needed for this poor-risk population. CD19, CD20, CD22, CD79a, CD38, CD30, LMP1 and LMP2 are attractive targets for immunotherapy in CAYA patients with R/R NHL. Novel anti-CD20 monoclonal antibodies, anti-CD38 monoclonal antibody, antibody drug conjugates and T and natural killer (NK)-cell bispecific and trispecific engagers are being investigated in the R/R setting and are changing the landscape of NHL therapy. A variety of cellular immunotherapies such as viral activated cytotoxic T-lymphocyte, chimeric antigen receptor (CAR) T-cells, NK and CAR NK-cells have been investigated and provide alternative options for CAYA patients with R/R NHL. Here, we provide an update and clinical practice guidance of utilizing these cellular and humoral immunotherapies in CAYA patients with R/R NHL.     

Chimeric antigen receptor T-cell therapy following autologous transplantation for secondary central nervous system lymphoma: A case report

Rationale:Chimeric antigen receptor (CAR) T-cell therapy is effective in treating relapsed and refractory B-cell non-Hodgkin lymphoma. However, because of the mortality risk associated with immune effector cell-associated neurotoxicity syndrome and pseudoprogression, patients with central nervous system (CNS) involvement are less likely to receive CAR T-cell therapy.Patients concerns:We report a case of a 61-year-old, male patient with intravascular large B-cell lymphoma who suffered a CNS relapse after standard chemotherapy.Diagnosis:A diagnosis of intravascular large B-cell lymphoma with CNS involvement was made.Interventions:We treated the patient using CAR T-cell therapy following a conditioning regimen consisting of thiotepa and busulfan and autologous stem cell transplantation. Although he experienced grade 1 cytokine release syndrome, no other serious adverse events, such as immune effector cell-associated neurotoxicity syndrome or pseudoprogression, were observed.Outcomes:The patient achieved complete remission after the CAR T-cell infusion.Lessons:CAR T-cell therapy following autologous stem cell transplantation is a viable option for relapsed/refractory lymphoma with CNS infiltration. Further clinical studies are warranted to verify its safety and efficacy.     

Accelerating chimeric antigen receptor therapy in chronic lymphocytic leukemia: The development and challenges of chimeric antigen receptor T-cell therapy for chronic lymphocytic leukemia

Studies of chimeric antigen receptor (CAR) T-cell therapy in chronic lymphocytic leukemia (CLL) have demonstrated the potential to produce deep remissions—and possibly cures—in some patients with heavily pretreated, high-risk, relapsed, and refractory disease. Unfortunately, most clinical trials of CAR T cells in CLL report complete responses only in the minority of patients, although recent studies have begun to elucidate the factors most predictive of response. These studies have suggested strategies for optimizing CAR T-cell fitness as well as the pre-existing host immune response, approaches that will likely lead to improvements in the efficacy of CAR T cells in CLL. Treating patients earlier in the course of their disease or using combination therapies with CAR T cells may further enhance efficacy. In this review, we summarize the existing literature on CAR T cell therapy in CLL, discuss mechanisms of response and resistance, and describe challenges facing the field.     

Hybrid hybridoma producing a bispecific monoclonal antibody that can focus effector T-cell activity

Previous studies have shown that heteroconjugates of monoclonal antibodies in which one of the component antibodies is directed at the T-cell receptor and the other is directed against any chosen site can focus effector T cells to function at the targeted site. We report here the production of a hybrid hybridoma cell line, H1.10.1.6, which secretes large amounts of a bispecific hybrid antibody of the IgG2a class, that can focus T-cell activity. The parental hybridoma lines for the secondary fusion were F23.1, which secretes an antibody specific for an allotypic determinant on the T-cell receptor of most mouse strains, and 19E12, secreting an anti-Thy-1.1 antibody. The bispecific hybrid antibody was partially purified by hydroxylapatite chromatography and characterized by isoelectric focusing. It efficiently targets Thy-1.1-expressing tumor cells for lysis by F23.1 receptor-positive cytotoxic T-cell clones in vitro. Such hybrid antibodies produced by hybrid hybridoma cell lines may have application in the therapeutic targeting of tumors or sites of viral infections for attack by T cells.     

Neutropenia and anaemia associated with T-cell large granular lymphocyte leukaemia responds to fludarabine with minimal toxicity

T-cell large granular lymphocyte leukaemia (T-LGL) is a clonal disorder of T cells associated with neutropenia and anaemia. The clinical consequences are recurrent infections and transfusion dependence. The optimum treatment for severely affected patients remains to be defined. Current therapies require long-term administration to maintain an effect. We report the reversal of severe neutropenia and/or anaemia in four patients treated with fludarabine which has been maintained since stopping treatment. The therapeutic side-effects were restricted to one episode of fever not associated with neutropenia. We conclude that fludarabine is effective in T-LGL, may be given safely despite severe neutropenia and induces durable treatment-free remissions.     

CAR T cell therapy for B-cell lymphomas

B-cell non-Hodgkin's lymphoma (NHLs)is a very heterogonous malignancy with diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) as the most common subtypes. Standard treatment with anti-CD20 based chemoimmunotherapy is usually very effective for disease control. However a significant proportion of patients with high-risk features (double hit lymphoma, transformed lymphomas or early relapses) will become refractory to standard therapies and will have limited alternatives for cure. Adoptive therapy with chimeric antigen receptor (CAR) T-cells is a new paradigm for effective treatment of poor prognosis lymphomas. Here we review the biology of poor risk DLBCL and FL, the rationale for CAR T-cell therapy in malignant lymphoma and the efficacy/toxicity profile of CD19 directed CAR T cell therapy for DLBCL and FL from early single center studies to multicenter/global clinical trial with different CAR T cell constructs.     

Challenges and opportunities of CAR T-cell therapies for CLL

Chimeric antigen receptor (CAR) T-cell therapies have transformed the treatment landscape of blood cancers. These engineered receptors which endow T cells with antibody-like target cell recognition combined with the typical T cell target cell lysis abilities. Introduced into the clinic in the 2010s, CAR T-cells have shown efficacy in chronic B lymphocytic leukemia (CLL), but a majority of patients do not achieve sustained remission. Here we discuss the current treatment landscape in CLL using small molecules and allogeneic stem cell transplantation, the niche CAR T-cells filled in this context, and what we have learned from biomarker and mechanistic studies. Several product parameters and improvements are introduced as examples of how the bedside-to-bench is translated into improved CAR T-cells for CLL. We hope to convey to our readers the crucial role translational medicine plays in transforming the treatment outcomes for patients with CLL and how this line of research is an essential component of modern medicine.     

New targets for CAR T therapy in hematologic malignancies

As we expand our acumen of the intricacies of hematological malignancies at a genetic and cellular level, we have paved the way in advancing novel targeted therapeutic avenues such as chimeric antigen receptor T-cell therapies (CAR T). Engineering cells to target a specific antigen has led to dramatic remission rates in cases of relapsed/refractory non-Hodgkin lymphoma, acute lymphoblastic leukemia as well as multiple myeloma thus far with trials in place to further advance targeted therapies in other hematological malignancies. Most currently available CAR T therapies target CD19 antigen. Studies are underway exploring novel CAR T products aimed at other tumor-specific antigens with potential to improve the efficacy and reduce the toxicities. Early studies have confirmed safety and efficacy of CD22 and BCMA targeted CAR T therapies. Moreover, various other targets including CD20, CD30, CD123, kappa, and lambda light chains among others are under clinical investigation as potential avenues of targeted therapy. This review highlights the shift in the treatment paradigm in pursuing diverse antigen targets while addressing the challenges in terms of the efficacy and toxicity of current CAR T-cell therapies.     

Sirolimus for the treatment of multi-resistant pure red cell aplasia

Patients with relapsed, refractory or advanced stage B non-Hodgkin lymphoma (NHL) continue to have a dismal prognosis. This review summarises current and novel cellular and immunotherapy for these high-risk populations, including haematopoietic stem cell transplant, bispecific antibodies, viral-derived cytotoxic T cells, chimeric antigen receptor (CAR) T cells, and natural killer (NK) cell therapy, as discussed at the 6th International Symposium on Childhood, Adolescent and Young Adult Non-Hodgkin Lymphoma on September 26th–29th 2018 in Rotterdam, the Netherlands, and explores the future of NK/CAR NK therapies.     

B lymphocyte function in multiple myeloma: analysis of T cell- and monocyte-dependent antibody production

T-cell and B-cell functions were studied in 35 patients with untreated multiple myeloma (MM) and in 16 patients with MM treated with prednisolone, melphalan and vincristine. The numbers of CD4+ T cells were normal in untreated MM patients, but markedly decreased in treated patients, whereas CD8+ cell numbers were normal in untreated and treated patients. Mitogen-induced as well as antigen-induced lymphocyte proliferative responses were reduced, but not further affected by treatment. The antigen-induced proliferative responses by lymphocytes of treated, but not of untreated patients, correlated positively to the proportions of CD4+ cells among MNC. Taken together, the findings suggest selective loss of CD4+ subpopulations during cytotoxic treatment. Pokeweed mitogen (PWM)-induced Ig production was generally low, but significantly reduced Ig production was only seen in experiments employing MM B cells and monocytes co-cultured with irradiated T-enriched cells. Irradiated MM T cells displayed normal helper function when co-cultured with normal B cells stimulated with PWM. MM B cells and monocytes cultured with irradiated normal T cells produced little Ig; however, MM monocytes were not suppressive. In 2 of 3 patients with either IgG-kappa or IgA-kappa myeloma, the numbers of PWM-stimulated B cells that produced kappa chains were somewhat higher than those found among normal MNC. The impaired ability of antibody production by B cells from untreated MM patients seems to relate to intrinsic B cell defect(s) rather than to abnormal regulation by T cells or monocytes. However, disturbances in the functions of CD4+ cells may be observed in treated MM.