Anti-CD138 chimeric antigen receptor-modified T cell therapy for multiple myeloma with extensive extramedullary involvement

Chimeric Antigen Receptor T Cells in Multiple Myeloma

Multiple myeloma is the second most common hematological malignancy with an approximate incidence of up to 8.5 cases per 100,000 persons per year. Over the last decade, therapy for multiple myeloma has undergone a revolutionary change. Chimeric antigen receptor (CAR) T-cell therapy has played a major role in this evolution. In this review, we discuss the existing state of CAR T-cell therapy in myeloma while evaluating several newer therapies and targets expected in the near future.

Reprogramming the tumor microenvironment by genome editing for precision cancer therapy

The tumor microenvironment (TME) is essential for immune escape by tumor cells. It plays essential roles in tumor development and metastasis. The clinical outcomes of tumors are often closely related to individual differences in the patient TME. Therefore, reprogramming TME cells and their intercellular communication is an attractive and promising strategy for cancer therapy. TME cells consist of immune and nonimmune cells. These cells need to be manipulated precisely and safely to improve cancer therapy. Furthermore, it is encouraging that this field has rapidly developed in recent years with the advent and development of gene editing technologies. In this review, we briefly introduce gene editing technologies and systematically summarize their applications in the TME for precision cancer therapy, including the reprogramming of TME cells and their intercellular communication. TME cell reprogramming can regulate cell differentiation, proliferation, and function. Moreover, reprogramming the intercellular communication of TME cells can optimize immune infiltration and the specific recognition of tumor cells by immune cells. Thus, gene editing will pave the way for further breakthroughs in precision cancer therapy.

A combination of humanized anti-BCMA and murine anti-CD38 CAR-T cell therapy in patients with relapsed or refractory multiple myeloma

Chimeric antigen receptor T (CAR-T) cells are a promising approach in hematopoietic malignancies. We evaluated the safety and efficacy of a combination of humanized anti-BCMA and murine anti-CD38 CAR-T cell therapy in patients with relapsed or refractory multiple myeloma (R/RMM). Twenty-two R/RMM patients, with a median age of 56 years and a median number of previous therapies of 8, were included in the study. Both CAR-T cells infusion doses were 2.0 × 10⁶/kg. The overall response rate (ORR) was 90.9%, with 12 patients (54.5%) achieving a strict complete response/complete response (sCR/CR). The 24-month overall survival (OS) rate was 56.6%, and the progression-free survival (PFS) rate was 48.7%. Cytokine release syndrome (CRS) of grades 1-2 occurred in 16 patients (72.7%) and of grade ≥3 in six patients (27.3%). Immune effector cell-associated neurotoxic syndrome (ICANS) of grades 1-2 occurred in three patients (13.6%). The combination therapy is potential in R/RMM patients.Trial registration: The patients were enrolled in clinical trials registered as ChiCTR1800017051.

High efficacy and safety of CD38 and BCMA bispecific CAR-T in relapsed or refractory multiple myeloma

Background

B-cell maturation antigen (BCMA) chimeric antigen receptor T (CAR-T) cell therapy has obtained promising results in relapsed or refractory multiple myeloma (R/R MM), while some patients do not response, or relapse in short term after treatment. Combining with anti-CD38 might solve the problem of targeting BCMA alone. We aimed to assess the efficacy and safety of BCMA and CD38 (BCMA-CD38) bispecific CAR-T cells in R/R MM patients.

Methods

We did a single-center, single-arm clinical study at the Second Affiliated Hospital of Yangtze University in China. Patients meeting with the inclusion criteria were administered with fludarabine and cyclophosphamide before CAR-T cells infusion. Response and adverse events were assessed after infusion. This study was registered with the Chinese Clinical Trial Registration Center (ChiCTR1900026286).

Results

First, we found BCMA-CD38 CAR-T cells exhibited enhanced killing effect on BCMA+CD38+ cells in vitro, compared to BCMA CAR-T and CD38 CAR-T cells. We further demonstrated its anti-tumor activity in vivo. Then, we enrolled 16 R/R MM patients for safety and efficacy analyses. Of the 16 evaluable patients, 14 (87.5%) respond to the treatment, including 13 stringent complete response (sCR) and one partial response (PR), while two patients did not respond. At a median follow-up of 11.5 months, of the 13 patients who achieved sCR, 76.9% (10/13) did not relapse or progress during follow-up. Relapse occurred in 3 patients (Patient 2, 3 and 4) after achieving sCR. In sum, four patients died, of which one died of hemophagocytic lymphohistiocytosis syndrome secondary to severe cytokine release syndrome (CRS) and three died of disease progression or relapse. The 1-year progression-free survival rates was 68.8%. The 1-year overall survival rate was 75.0%. Extramedullary lesions were eliminated in 62.5% (5/8) patients. The most common symptoms after CAR-T infusion were cytopenia (16, 100%), fever (10, 62.5%), fatigue (8, 50.0%) and myalgias (8, 50.0%). Twelve patients (75.0%) were observed with various grades of CRS, of which five patients (31.3%) got serious CRS (Grade ≥ 3). The CAR+ cell expansion levels were associated with the severity of CRS. Transient clonal isotype switch was observed after CAR-T infusion.

Conclusion

Our results confirm that BCMA-CD38 CAR-T cells therapy is feasible in treating R/R MM patients, with high response rate, low recurrence rate and manageable CRS, which will be a promising treatment option for R/R MM.

Trial registration

ChiCTR1900026286, registered on September 29, 2019, retrospectively registered, URL: https://www.chictr.org.cn/showproj.aspx?proj=43805

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02214-z.

Promising Antigens for the New Frontier of Targeted Immunotherapy in Multiple Myeloma

Simple Summary

Defining the specificity and biological sequalae induced by receptors differentiated expressed in multiple myeloma cells are critical for the development of effective immunotherapies based on monoclonal antibodies. Ongoing studies continue to discover new antigens with superior tumor selectivity and defined function in regulating the pathophysiology of myeloma cells directly or indirectly in the immunosuppressive bone marrow microenvironment. Meanwhile, it is urgent to identify mechanisms of immune resistance and design more potent immunotherapies, alone and/or with best combination partners to further prolong anti-MM immunity.

Abstract

The incorporation of novel agents in recent treatments in multiple myeloma (MM) has improved the clinical outcome of patients. Specifically, the approval of monoclonal antibody (MoAb) against CD38 (daratumumab) and SLAMF7 (elotuzumab) in relapsed and refractory MM (RRMM) represents an important milestone in the development of targeted immunotherapy in MM. These MoAb-based agents significantly induce cytotoxicity of MM cells via multiple effector-dependent mechanisms and can further induce immunomodulation to repair a dysfunctional tumor immune microenvironment. Recently, targeting B cell maturation antigen (BCMA), an even MM-specific antigen, has shown high therapeutic activities by chimeric antigen receptor T cells (CAR T), antibody-drug conjugate (ADC), bispecific T-cell engager (BiTE), as well as bispecific antibody (BiAb), with some already approved for heavily pretreated RRMM patients. New antigens, such as orphan G protein-coupled receptor class C group 5 member D (GPRC5D) and FcRH5, were identified and rapidly moved to ongoing clinical studies. We here summarized the pathobiological function of key MM antigens and the status of the corresponding immunotherapies. The potential challenges and emerging treatment strategies are also discussed.

Clinical development of CAR T cell therapy in China: 2020 update

Chimeric antigen receptor (CAR) T-cell therapy has achieved significant success in the treatment of hematological malignancies. In recent years, fast-growing CAR T clinical trials have actively explored their potential application scenarios. According to the data from the clinicaltrials.gov website, China became the country with the most registered CAR T trials in September 2017. As of June 30, 2020, the number of registered CAR T trials in China has reached 357. In addition, as many as 150 other CAR T trials have been registered on ChiCTR. Although CAR T therapy is flourishing in China, there are still some problems that cannot be ignored. In this review, we aim to systematically summarize the clinical practice of CAR T-cell therapy in China. This review will provide an informative reference for colleagues in the field, and a better understanding of the history and current situation will help us more reasonably conduct research and promote cooperation.

Chimeric Antigen Receptor T-cell Therapy for Multiple Myeloma

Relapsed/refractory multiple myeloma (MM) remains a significant clinical challenge, despite a wide array of approved therapeutic agents. Immunotherapy offers an advantage in this setting. Chimeric antigen receptor (CAR) modified T-cells have transformed care for patients with hematologic malignancies. CAR-T cells targeting CD-19 B-cell lymphoma cells have shown prominent activity in lymphoma and acute lymphoblastic leukemia. Recently, the CAR-T cell platform for MM demonstrated therapeutic benefit. Hence, it is rapidly progressing. The most commonly tested target for MM is the B-cell maturation antigen. Complexities involved in the generation and use of CAR-T cells for MM include the identification of appropriate target antigens that are specific, and tumor type restricted, in addition to the optimization of CAR constructs to mitigate toxicities including cytokine release syndrome. CAR-T cells hold immense promise as a therapeutic modality for the treatment of MM. In this article, we provide an updated review of clinical trials of MM-specific CAR-T cells.

Rational design of a trimeric APRIL-based CAR-binding domain enables efficient targeting of multiple myeloma

Chimeric antigen receptor (CAR) T cells (CARTs) have shown tremendous potential for the treatment of certain B-cell malignancies, including patients with relapsed/refractory multiple myeloma (MM). Targeting the B-cell maturation antigen (BCMA) has produced the most promising results for CART therapy of MM to date, but not all remissions are sustained. Emergence of BCMA escape variants has been reported under the selective pressure of monospecific anti-BCMA CART treatment. Thus, there is a clinical need for continuous improvement of CART therapies for MM. Here, we show that a novel trimeric APRIL (a proliferation-inducing ligand)-based CAR efficiently targets both BCMA+ and BCMA- MM. Modeled after the natural ligand-receptor pair, APRIL-based CARs allow for bispecific targeting of the MM-associated antigens BCMA and transmembrane activator and CAML interactor (TACI). However, natural ligands as CAR antigen-binding domains may require further engineering to promote optimal binding and multimerization to adequately trigger T-cell activation. We found that using a trimeric rather than a monomeric APRIL format as the antigen-binding domain enhanced binding to BCMA and TACI and CART activity against MM in vitro and in vivo. Dual-specific, trimeric APRIL-based CAR are a promising therapeutic approach for MM with potential for preventing and treating BCMA escape.

Dual Targeting to Overcome Current Challenges in Multiple Myeloma CAR T-Cell Treatment

In the era of highly promising novel targeted-immunotherapy strategies for multiple myeloma (MM), the first series of clinical trials with CAR T-cells targeting the plasma cell-specific B-cell maturation antigen (BCMA) have shown excellent response rates. In the long-term, however, MM appears to escape the therapy likely due to initial low and heterogeneous expression or downregulation of BCMA expression. Several other molecules targeted by CAR T-cells in MM are expressed at high levels on MM cells, but many of these attractive targets are also expressed on various, sometimes vital non-malignant cells, posing major risks for on-target, off-tumor side effects. CAR T-cell therapy for MM therefore faces two urgent challenges: (i) improving the efficacy of BCMA CAR T-cells and (ii) establishing a MM-selectivity even when CAR T-cells are directed against not entirely MM-specific target antigens. In this review, we will outline the current attempts to tackle these challenges, with a specific focus on how dual CAR targeting might be applied to tackle both issues.

CAR T-Cells in Multiple Myeloma: State of the Art and Future Directions

Despite recent therapeutic advances, the prognosis of multiple myeloma (MM) patients remains poor. Thus, new strategies to improve outcomes are imperative. Chimeric antigen receptor (CAR) T-cell therapy has changed the treatment landscape of B-cell malignancies, providing a potentially curative option for patients who are refractory to standard treatment. Long-term remissions achieved in patients with acute lymphoblastic leukemia and Non-Hodgkin Lymphoma encouraged its further development in MM. B-cell maturation antigen (BCMA)-targeted CAR T-cells have established outstanding results in heavily pre-treated patients. However, several other antigens such as SLAMF7 and CD44v6 are currently under investigation with promising results. Idecabtagene vicleucel is expected to be approved soon for clinical use. Unfortunately, relapses after CAR T-cell infusion have been reported. Hence, understanding the underlying mechanisms of resistance is essential to promote prevention strategies and to enhance CAR T-cell efficacy. In this review we provide an update of the most recent clinical and pre-clinical data and we elucidate both, the potential and the challenges of CAR T-cell therapy in the future.

B-cell maturation antigen-specific chimeric antigen receptor T cells for multiple myeloma: Clinical experience and future perspectives

Despite major advances in the treatment of multiple myeloma (MM), it remains a largely incurable disease with long-term control often dependent on continuous therapy. More effective, better tolerated treatments are therefore required to achieve durable remissions and to improve the quality of life of MM patients. Adoptive immunotherapy employing T cells expressing chimeric antigen receptors (CAR) is currently among the most promising treatment approaches in cancer. Within the target portfolio for MM immunotherapy, B-cell maturation antigen (BCMA) is among the most widely studied target antigens. BCMA is consistently expressed on MM cells and, importantly, is not expressed in critical healthy tissue. For this reason, it is an ideal target for MM immunotherapy. Several clinical trials evaluating different BCMA-targeting CAR constructs have been initiated and early results are very promising. However, in this rapidly developing clinical landscape, the ultimate role of BCMA-specific CAR-T cell therapy remains unclear. In this review, we will summarize currently available clinical data on BCMA-directed CAR-T cells and discuss potential future perspective for this promising treatment approach in MM.

Role of cell surface proteoglycans in cancer immunotherapy

Over the past few decades, understanding how tumor cells evade the immune system and their communication with their tumor microenvironment, has been the subject of intense investigation, with the aim of developing new cancer immunotherapies. The current therapies against cancer such as monoclonal antibodies against checkpoint inhibitors, adoptive T-cell transfer, cytokines, vaccines, and oncolytic viruses have managed to improve the clinical outcome of the patients. However, in some tumor entities, the response is limited and could benefit from the identification of novel therapeutic targets. It is known that tumor-extracellular matrix interplay and matrix remodeling are necessary for anti-tumor and pro-tumoral immune responses. Proteoglycans are dominant components of the extracellular matrix and are a highly heterogeneous group of proteins characterized by the covalent attachment of a specific linear carbohydrate chain of the glycosaminoglycan type. At cell surfaces, these molecules modulate the expression and activity of cytokines, chemokines, growth factors, adhesion molecules, and function as signaling co-receptors. By these mechanisms, proteoglycans influence the behavior of cancer cells and their microenvironment during the progression of solid tumors and hematopoietic malignancies. In this review, we discuss why cell surface proteoglycans are attractive pharmacological targets in cancer, and we present current and recent developments in cancer immunology and immunotherapy utilizing proteoglycan-targeted strategies.

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.

CAR-T cells beyond CD19, UnCAR-Ted territory

CAR-T cells have made dramatic inroads in targeting CD19-positive B-cell malignancies. This review focuses on application of CAR-T cells in hematologic malignancies beyond targeting CD19, with specific attention to Hodgkin's lymphoma and acute myeloid leukemia.

Safety and efficacy of targeting CD138 with a chimeric antigen receptor for the treatment of multiple myeloma

After unprecedented successes in B-cell malignancies, chimeric antigen receptor T cells have recently been investigated for the treatment of multiple myeloma. Chimeric antigen receptor targeting T cells B-cell maturation antigen (BCMA) on malignant plasma cells have led to impressive clinical responses in recent trials. However, BCMA-negative relapses have been observed, supporting the need for complementary treatment strategies. Here, we explored the feasibility of targeting CD138 (syndecan-1), a surface marker expressed on both normal and malignant plasma cells. We showed that T cells from both healthy donors and from multiple myeloma patients, when transduced with a CD138-specific chimeric antigen receptor, can eliminate tumor cell lines and primary myeloma cells both in vitro and in vivo. CD138 is also expressed by putative myeloma stem cells identified by Hoechst staining, and these cells can be eliminated by CD138-specific chimeric antigen receptor T cells. Preclinical analyses did not identify any on target off tumor cytotoxicity against normal epithelial or endothelial cells, further supporting the rationale for the use of adoptively transferred CD138-specific chimeric antigen receptor T cells for the treatment of patients with relapsed/refractory multiple myeloma.

A novel luciferase-based assay for the detection of Chimeric Antigen Receptors

Chimeric Antigen Receptor-T (CAR-T) cell immunotherapy has produced dramatic responses in hematologic malignancies. One of the challenges in the field is the lack of a simple assay for the detection of CARs on the surface of immune effector cells. In this study, we describe a novel luciferase-based assay, termed Topanga Assay, for the detection of CAR expression. The assay utilizes a recombinant fusion protein, called Topanga reagent, generated by joining the extra-cellular domain of a CAR-target in frame with one of the marine luciferases or their engineered derivatives. The assay involves incubation of CAR expressing cells with the Topanga reagent, a few washes and measurement of luminescence. The assay can detect CARs comprising either immunoglobulin- or non-immunoglobulin-based antigen binding domains. We further demonstrate that addition of epitope tags to the Topanga reagent not only allows its convenient one step purification but also extends its use for detection of CAR cells using flow cytometry. However, crude supernatant containing the secreted Topanga reagent can be directly used in both luminescence and flow-cytometry based assays without prior protein purification. Our results demonstrate that the Topanga assay is a highly sensitive, specific, convenient, economical and versatile assay for the detection of CARs.

Glycan-directed CAR-T cells

Cancer immunotherapy is rapidly advancing in the treatment of a variety of hematopoietic cancers, including pediatric acute lymphoblastic leukemia and diffuse large B cell lymphoma, with chimeric antigen receptor (CAR)-T cells. CARs are genetically encoded artificial T cell receptors that combine the antigen specificity of an antibody with the machinery of T cell activation. However, implementation of CAR technology in the treatment of solid tumors has been progressing much slower. Solid tumors are characterized by a number of challenges that need to be overcome, including cellular heterogeneity, immunosuppressive tumor microenvironment (TME), and, in particular, few known cancer-specific targets. Post-translational modifications that differentially occur in malignant cells generate valid cell surface, cancer-specific targets for CAR-T cells. We previously demonstrated that CAR-T cells targeting an aberrant O-glycosylation of MUC1, a common cancer marker associated with changes in cell adhesion, tumor growth and poor prognosis, could control malignant growth in mouse models. Here, we discuss the field of glycan-directed CAR-T cells and review the different classes of antibodies specific for glycan-targeting, including the generation of high affinity O-glycopeptide antibodies. Finally, we discuss historic and recently investigated glycan targets for CAR-T cells and provide our perspective on how targeting the tumor glycoproteome and/or glycome will improve CAR-T immunotherapy.

Clinical characteristics and prognosis of multiple myeloma with bone-related extramedullary disease at diagnosis

Multiple myeloma (MM) is a hematological neoplasm which results in diffuse or focal bone infiltration and extramedullary lesions. It's reported that infiltration of organs by plasma cells indicated worse prognosis, but the prognosis of patients with bone-related extramedullary disease (bEMD) is still unknown. One hundred and fourteen newly diagnosed MM patients were retrospectively reviewed. Results showed that the clinical features, overall survival (OS), and progression-free survival (PFS) of patients with and without bEMD had no statistical significance. Rib (46.1%) and vertebrae (17.9%) are common sites bEMD involved. Patients with diffuse bEMD had worse prognosis compared with patients with focal bEMD. Bisphosphonates played an important role in prolonging the survival of patients with bEMD. Positron emission tomography (PET)/computed tomography (CT) is sensitive in discovering bEMD than whole body low dose CT suggesting PET/CT to be a promising technique for initial staging. High β2-microglobulin and low albumin indicated shorter survival in patients with bEMD.

Correlation Between Baseline 18F-FDG PET/CT Findings and CD38- and CD138-Expressing Myeloma Cells in Bone Marrow and Clinical Parameters in Patients with Multiple Myeloma

Objective

The aim of this study was to evaluate the relation between the rate of fluorine-18 (18F) fludeoxyglucose (FDG) uptake and CD38 and CD138 expression in myeloma cells in bone marrow and other clinical parameters in patients with multiple myeloma (MM).

Materials and Methods

Patients with the diagnosis of MM who underwent 18F-FDG positron emission tomography/computed tomography (PET/CT) for initial staging were evaluated retrospectively. We analyzed a total of 42 patients (43-83 years old, mean: 64.4±9.9). Hematological and biochemical tests including hemoglobin, hematocrit, C-reactive protein, β2-microglobulin, creatinine, albumin, calcium, lactate dehydrogenase, and erythrocyte sedimentation rate were recorded. In bone marrow samples, plasma cell ratio and CD38 and CD138 immunohistochemical staining were evaluated. On PET/CT images, mean standardized uptake values (SUV_mean) of the right anterior and posterior iliac crest and right proximal femora were calculated. The correlations between the average SUV_mean of bone marrow and CD38- and CD138-expressing myeloma cells and other parameters were analyzed by Spearman’s correlation test. Values of p<0.05 were considered statistically significant.

Results

Types of MM were IgG_K (45%), IgG_L (21%), IgA_K (7%), IgA_L (10%), and others (17%). Thirty-two (76%) patients were at stage III according to the Salmon-Durie staging system. There was a statistically significant positive correlation between bone marrow FDG uptake and percentage of plasma cells in bone marrow and CD38 and CD138 expression in plasma cells (r=0.403, r=0.339, and r=0.409) and β2-microglobulin and C-reactive protein levels (r=0.676, r=0.541). There was a negative correlation between bone marrow FDG uptake and hemoglobin and hematocrit values (r=-0.377 and r=-0.368). Other hematological parameters were not correlated with FDG uptake in bone marrow.

Conclusion

Increased FDG uptake is correlated with the percentage of CD38 and CD138 expression in plasma cells in bone marrow. In addition to initial staging, 18F-FDG PET/CT is useful in treatment planning and prognostic evaluation in MM patients.