Recent Advances in CAR-T Cell Therapy for Non-Hodgkin Lymphoma

Extracellular domain, hinge, and transmembrane determinants affecting surface CD4 expression of a novel anti-HIV chimeric antigen receptor (CAR) construct

Chimeric antigen receptor (CAR)-T cells have demonstrated clinical potential, but current receptors still need improvements to be successful against chronic HIV infection. In this study, we address some requirements of CAR motifs for strong surface expression of a novel anti-HIV CAR by evaluating important elements in the extracellular, hinge, and transmembrane (TM) domains. When combining a truncated CD4 extracellular domain and CD8α hinge/TM, the novel CAR did not express extracellularly but was detectable intracellularly. By shortening the CD8α hinge, CD4-CAR surface expression was partially recovered and addition of the LYC motif at the end of the CD8α TM fully recovered both intracellular and extracellular CAR expression. Mutation of LYC to TTA or TTC showed severe abrogation of CAR expression by flow cytometry and confocal microscopy. Additionally, we determined that CD4-CAR surface expression could be maximized by the removal of FQKAS motif at the junction of the extracellular domain and the hinge region. CD4-CAR surface expression also resulted in cytotoxic CAR T cell killing of HIV Env+ target cells. In this study, we identified elements that are crucial for optimal CAR surface expression, highlighting the need for structural analysis studies to establish fundamental guidelines of CAR designs.

Extracellular domain, hinge, and transmembrane determinants affecting surface CD4 expression of a novel anti-HIV chimeric antigen receptor (CAR) construct

Chimeric antigen receptor (CAR)-T cells have demonstrated clinical potential, but current receptors still need improvements to be successful against chronic HIV infection. In this study, we address some requirements of CAR motifs for strong surface expression of a novel anti-HIV CAR by evaluating important elements in the extracellular, hinge, and transmembrane (TM) domains. When combining a truncated CD4 extracellular domain and CD8α hinge/TM, the novel CAR did not express extracellularly but was detectable intracellularly. By shortening the CD8α hinge, CD4-CAR surface expression was partially recovered and addition of the LYC motif at the end of the CD8α TM fully recovered both intracellular and extracellular CAR expression. Mutation of LYC to TTA or TTC showed severe abrogation of CAR expression by flow cytometry and confocal microscopy. Additionally, we determined that CD4-CAR surface expression could be maximized by the removal of FQKAS motif at the junction of the extracellular domain and the hinge region. CD4-CAR surface expression also resulted in cytotoxic CAR T cell killing of HIV Env+ target cells. In this study, we identified elements that are crucial for optimal CAR surface expression, highlighting the need for structural analysis studies to establish fundamental guidelines of CAR designs.

A phase 1 first-in-human study of GS-0189, an anti-signal regulatory protein alpha (SIRPα) monoclonal antibody, in patients with relapsed/refractory (R/R) non-Hodgkin lymphoma (NHL)

Signal regulatory protein alpha (SIRPα) is the receptor for cluster of differentiation (CD)47, a potent "don't eat me" signal for macrophages. Disruption of CD47-SIRPα signaling in the presence of prophagocytic signals can lead to enhanced phagocytosis of tumor cells, resulting in a direct antitumor effect; agents targeting this pathway have shown efficacy in non-Hodgkin lymphoma (NHL) and other tumor types. GS-0189 is a novel anti-SIRPα humanized monoclonal antibody. Here we report: (1) clinical safety, preliminary activity, and pharmacokinetics of GS-0189 as monotherapy and in combination with rituximab from a phase 1 clinical trial in patients with relapsed/refractory NHL (NCT04502706, SRP001); (2) in vitro characterization of GS-0189 binding to SIRPα; and (3) in vitro phagocytic activity. Clinically, GS-0189 was well tolerated in patients with relapsed/refractory NHL with evidence of clinical activity in combination with rituximab. Receptor occupancy (RO) of GS-0189 was highly variable in NHL patients; binding affinity studies showed significantly higher affinity for SIRPα variant 1 than variant 2, consistent with RO in patient and healthy donor samples. In vitro phagocytosis induced by GS-0189 was also SIRPα variant-dependent. Although clinical development of GS-0189 was discontinued, the CD47-SIRPα signaling pathway remains a promising therapeutic target and should continue to be explored.

Expression of CD22 in Triple-Negative Breast Cancer: A Novel Prognostic Biomarker and Potential Target for CAR Therapy

Triple-negative breast cancer (TNBC) accounts for 15-20% of all breast cancer cases. Due to the lack of expression of well-known molecular targets [estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2)], there is a need for more alternative treatment approaches in TNBC. Chimeric antigen receptor (CAR)-T cell-based immunotherapy treatment is one of the latest treatment technologies with outstanding therapeutic advances in the past decade, especially in the treatment of hematologic malignancies, but the therapeutic effects of CAR-T cells against solid tumors have not yet shown significant clinical benefits. Identification of highly specific CAR-T targets in solid tumors is also crucial for its successful treatment. CD22 is reported to be a multifunctional receptor that is mainly expressed on the surface of mature B-cells (lymphocytes) and is also highly expressed in most B-cell malignancies. This study aimed to investigate the expression of CD22 in TNBC. Bioinformatic analysis was performed to evaluate the expression of CD22 in breast carcinoma and normal tissues. RNA-seq data of normal and breast carcinoma patients were downloaded from The Cancer Genome Atlas (TCGA), and differential gene expression was performed using R language. Additionally, online bioinformatics web tools (GEPIA and TNM plot) were used to evaluate the expression of CD22 in breast carcinoma and normal tissues. Western blot (WB) analysis and immunofluorescence (IF) were performed to characterize the expression of CD22 in TNBC cell lines. Immunohistochemical (IHC) staining was performed on tumor specimens from 97 TNBC patients for CD22 expression. Moreover, statistical analysis was performed to analyze the association of clinical pathological parameters with CD22 expression. Correlation analysis between overall survival data of TNBC patients and CD22 expression was also performed. Differential gene expression analysis of TCGA data revealed that CD22 is among the upregulated differentially expressed genes (DEGs) with high expression in breast cancer, as compared to normal breast tissues. WB and IF analysis revealed high expression of CD22 in TNBC cell lines. IHC results also showed that approximately 62.89% (61/97) of TNBC specimens were stained positive for CD22. Cell membrane expression of CD22 was evident in 23.71% (23/97) of TNBC specimens, and 39.18% (38/97) of TNBC specimens showed cytoplasmic/membrane expression, while 37.11% (36/97) specimens were negative for CD22. Furthermore, significant associations were found between the size of tumors in TNBC patients and CD22 expression, which unveils its potential as a prognostic biomarker. No significant correlation was found between the overall survival of TNBC patients and CD22 expression. In conclusion, we demonstrated for the first time that CD22 is highly expressed in TNBC. Based on our findings, we anticipated that CD22 could be used as a prognostic biomarker in TNBC, and it might be a potential CAR-T target in TNBC for whom few therapeutic options exist. However, more large-scale studies and clinical trials will ensure its potential usefulness as a CAR-T target in TNBC.

The Role of Bispecific Antibodies in Non-Hodgkin's Lymphoma: From Structure to Prospective Clinical Use

Bispecific antibodies (bsAbs) are molecules that simultaneously bind two different antigens (Ags). bsAbs represent a very active field in tumor immunotherapy with more than one hundred molecules currently being tested. More specifically, they have elicited a great interest in the setting of non-Hodgkin's lymphoma (NHLs), where they could represent a viable option for more fragile patients or those resistant to other conventional therapies. This review aims to give a brief overview of the different available bsAb formats and their mechanisms of action, pinpointing the differences between IgG-like and non-IgG-like classes and will then focus on those in advanced clinical development for NHLs.

A Comprehensive Review of Recent Advancements in Cancer Immunotherapy and Generation of CAR T Cell by CRISPR-Cas9

The mechanisms involved in immune responses to cancer have been extensively studied for several decades, and considerable attention has been paid to harnessing the immune system’s therapeutic potential. Cancer immunotherapy has established itself as a promising new treatment option for a variety of cancer types. Various strategies including cancer vaccines, monoclonal antibodies (mAbs), adoptive T-cell cancer therapy and CAR T-cell therapy have gained prominence through immunotherapy. However, the full potential of cancer immunotherapy remains to be accomplished. In spite of having startling aspects, cancer immunotherapies have some difficulties including the inability to effectively target cancer antigens and the abnormalities in patients’ responses. With the advancement in technology, this system has changed the genome-based immunotherapy process in the human body including the generation of engineered T cells. Due to its high specificity, CRISPR-Cas9 has become a simple and flexible genome editing tool to target nearly any genomic locus. Recently, the CD19-mediated CAR T-cell (chimeric antigen receptor T cell) therapy has opened a new avenue for the treatment of human cancer, though low efficiency is a major drawback of this process. Thus, increasing the efficiency of the CAR T cell (engineered T cells that induce the chimeric antigen receptor) by using CRISPR-Cas9 technology could be a better weapon to fight against cancer. In this review, we have broadly focused on recent immunotherapeutic techniques against cancer and the use of CRISPR-Cas9 technology for the modification of the T cell, which can specifically recognize cancer cells and be used as immune-therapeutics against cancer.

Phase I study of CBM.CD19 chimeric antigen receptor T cell in the treatment of refractory diffuse large B-cell lymphoma in Chinese patients

Anti-CD19 chimeric antigen receptor (CAR) T cell therapy has shown impressive efficacy in treating B-cell malignancies. A single-center phase I dose-escalation study was conducted to evaluate the safety and efficacy of T cells transduced with CBM.CD19 CAR, a second-generation anti-CD19 CAR bearing 4-1BB costimulatory molecule, for the treatment of patients with refractory diffuse large B-cell lymphoma (DLBCL). Ten heavily treated patients with refractory DLBCL were given CBM.CD19 CAR-T cell (C-CAR011) treatment. The overall response rate was 20% and 50% at 4 and 12 weeks after the infusion of C-CAR011, respectively, and the disease control rate was 60% at 12 weeks after infusion. Treatment-emergent adverse events occurred in all patients. The incidence of cytokine release syndrome in all grades and grade ⩾ 3 was 90% and 0, respectively, which is consistent with the safety profile of axicabtagene ciloleucel and tisagenlecleucel. Neurotoxicity or other dose-limiting toxicities was not observed in any dose cohort of C-CAR011 therapy. Antitumor efficacy was apparent across dose cohorts. Therefore, C-CAR011 is a safe and effective therapeutic option for Chinese patients with refractory DLBCL, and further large-scale clinical trials are warranted.

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.

Immunotherapy in the treatment of lymphoma

Relapsed or refractory non-Hodgkin’s lymphomas, especially diffuse large B-cell lymphoma as well as relapsed or refractory Hodgkin lymphomas are hard-to-treat diseases. Patients who do not respond to initial therapy or experience relapse are treated with salvage regimens, and if eligible for aggressive therapy, treatment is continued with high-dose chemotherapy and autologous stem cell transplantation. Current therapy options can cure substantial numbers of patients, however for some it is still an uncurable disease. Numerous new drugs and cell therapies are being investigated for the treatment of relapsed or refractory lymphomas. Different types of immunotherapy options have shown promising results, and some have already become the standard of care. Here, we review immunotherapy options for the treatment of lymphoma and discuss the results, positions, practical aspects, and future directions of different drugs and cellular therapies for the treatment of this disease.

A Deep Insight Into CAR-T Cell Therapy in Non-Hodgkin Lymphoma: Application, Opportunities, and Future Directions

Non-Hodgkin's lymphoma (NHL) is a cancer that starts in the lymphatic system. In NHL, the important part of the immune system, a type of white blood cells called lymphocytes become cancerous. NHL subtypes include marginal zone lymphoma, small lymphocytic lymphoma, follicular lymphoma (FL), and lymphoplasmacytic lymphoma. The disease can emerge in either aggressive or indolent form. 5-year survival duration after diagnosis is poor among patients with aggressive/relapsing form of NHL. Therefore, it is necessary to understand the molecular mechanisms of pathogenesis involved in NHL establishment and progression. In the next step, we can develop innovative therapies for NHL based on our knowledge in signaling pathways, surface antigens, and tumor milieu of NHL. In the recent few decades, several treatment solutions of NHL mainly based on targeted/directed therapies have been evaluated. These approaches include B-cell receptor (BCR) signaling inhibitors, immunomodulatory agents, monoclonal antibodies (mAbs), epigenetic modulators, Bcl-2 inhibitors, checkpoint inhibitors, and T-cell therapy. In recent years, methods based on T cell immunotherapy have been considered as a novel promising anti-cancer strategy in the treatment of various types of cancers, and particularly in blood cancers. These methods could significantly increase the capacity of the immune system to induce durable anti-cancer responses in patients with chemotherapy-resistant lymphoma. One of the promising therapy methods involved in the triumph of immunotherapy is the chimeric antigen receptor (CAR) T cells with dramatically improved killing activity against tumor cells. The CAR-T cell-based anti-cancer therapy targeting a pan-B-cell marker, CD19 is recently approved by the US Food and Drug Administration (FDA) for the treatment of chemotherapy-resistant B-cell NHL. In this review, we will discuss the structure, molecular mechanisms, results of clinical trials, and the toxicity of CAR-T cell-based therapies. Also, we will criticize the clinical aspects, the treatment considerations, and the challenges and possible drawbacks of the application of CAR-T cells in the treatment of NHL.

Selecting the Optimal CAR-T for the Treatment of B-Cell Malignancies

PURPOSE OF REVIEW

Chimeric antigen receptor T-cell (CAR-T) therapy is a form of adoptive cellular therapy that has revolutionized the treatment landscape in hematologic malignancies, especially B-cell lymphomas. In this review, we will discuss some of the landmark data behind these therapies and then lay out our approach to utilizing this new therapy.

RECENT FINDINGS

CD19-directed CAR-Ts are the most common type currently used in treatment of relapsed B-cell lymphoid neoplasms. There are currently three FDA-approved products: axicabtagene ciluecel and tisagenlecleucel for the treatment of relapsed/refractory large B-cell lymphoma and pediatric B-cell acute lymphocytic leukemia (tisagenlecleucel only) and brexucabtagene autoleucel for the treatment of relapsed/refractory mantle cell lymphoma. These therapies are associated with distinctive acute toxicities such as cytokine release syndrome and neurotoxicity and chronic toxicities such as cytopenias and hypogammaglobulinemia. CAR-T therapy provides significant potential in the treatment of relapsed B-cell lymphomas despite current limitations. Several novel CAR cell designs are currently being studied in clinical trials which include tandem CAR-Ts, allogeneic CAR-Ts, and CAR-NK cells.

Tumor-tagging by oncolytic viruses: A novel strategy for CAR-T therapy against solid tumors

Chimeric antigen receptor (CAR) T cell therapy is one of the most promising immunotherapies in the past decade. It brings hope for cure to patients with previously refractory hematological malignancies. However, when translating this strategy into non-hematologic malignancies, the antitumor activity from multiple clinical studies seemed to be subtle or transient. The less satisfying efficacy in solid tumors might at least due to antigen heterogeneity, suboptimal CAR-T cell trafficking and tumor immunosuppressive environment. Here, we will review the updating strategies to challenge the therapeutic impediments of CAR-T therapy in non-hematologic malignancies. We mainly focus on the combination with oncolytic viruses (OV), the born allies for CAR-T cells. In addition to previously reported OVs-arming strategy, we discuss recently proposed tumor-tagging concept by OVs as CAR-T targets, as well as the possible improvements. Overall, tumor-tagging strategy by OVs combination with CAR-T would be a novel and promising solution for the heterogeneity and immunosuppressive microenvironment of solid tumors.

Fundamentals of immunology for understanding immunotherapy for lymphoma

An effective antitumor immune response in patients with lymphoma would eradicate the malignant B cells and cure the patient of the disease. This, however, does not occur, and a suboptimal antitumor response results in persistence and subsequent progression of the patient's disease. The goals of immunotherapy are therefore to restore an effective antitumor immune response by promoting immune recognition, optimizing immune activation, and supporting persistence of the immune response resulting in subsequent immunological memory. Multiple mechanisms, however, are present within the tumor microenvironment that account for an inadequate immune response. These include loss of major histocompatibility complex expression on tumor cells and subsequent inadequate antigen presentation, increased expression of immunosuppressive ligands on malignant cells, populations of immune cells with suppressive function present in the tumor, and cytokines secreted by the malignant cell or other cells in the microenvironment that promote immune exhaustion or suppress the immune response. Successful immunotherapeutic strategies are specifically addressing these issues by promoting antigen presentation, improving recognition of the malignant cell, directly activating T cells and natural killer cells, and blocking immune checkpoint signaling that would suppress the immune response. Many of these approaches have proven highly successful in patients with various subtypes of lymphoma and are now being incorporated into standard clinical practice.

Fundamentals of immunology for understanding immunotherapy for lymphoma

An effective antitumor immune response in patients with lymphoma would eradicate the malignant B cells and cure the patient of the disease. This, however, does not occur, and a suboptimal antitumor response results in persistence and subsequent progression of the patient's disease. The goals of immunotherapy are therefore to restore an effective antitumor immune response by promoting immune recognition, optimizing immune activation, and supporting persistence of the immune response resulting in subsequent immunological memory. Multiple mechanisms, however, are present within the tumor microenvironment that account for an inadequate immune response. These include loss of major histocompatibility complex expression on tumor cells and subsequent inadequate antigen presentation, increased expression of immunosuppressive ligands on malignant cells, populations of immune cells with suppressive function present in the tumor, and cytokines secreted by the malignant cell or other cells in the microenvironment that promote immune exhaustion or suppress the immune response. Successful immunotherapeutic strategies are specifically addressing these issues by promoting antigen presentation, improving recognition of the malignant cell, directly activating T cells and natural killer cells, and blocking immune checkpoint signaling that would suppress the immune response. Many of these approaches have proven highly successful in patients with various subtypes of lymphoma and are now being incorporated into standard clinical practice.

Perceptions of community hematologists/oncologists on barriers to chimeric antigen receptor T-cell therapy for the treatment of diffuse large B-cell lymphoma

Objective: To determine the perceptions of US community-based hematologists/oncologists regarding approved CAR-T therapies in relapsed/refractory large B-cell lymphoma and barriers to their adoption in practice. Materials & methods: In February and November 2019, US physicians with diverse geographic representation submitted responses via a web-based survey prior to or via an audience response system at the live meetings. Results: In February and November, 46 and 29% of physicians indicated that they had not referred any patients for CAR-T therapy, respectively. Cumbersome logistics, high cost and toxicity were defined as major barriers to prescribing CAR-T therapy. Conclusions: These findings highlight a need to improve processes, and address costs, to ensure timely access to this potentially curative therapy for relapsed/refractory large B-cell lymphoma patients.

Galunisertib enhances chimeric antigen receptor-modified T cell function

Chimeric antigen receptor (CAR) T cell therapy still faces the challenge of immunosuppression when treating solid tumors. TGF-β is one of the critical factors in the tumor microenvironment to help tumors escape surveillance by the immune system. Here we tried using the combination of a small molecule inhibitor of TGF-β receptor I, Galunisertib, and CAR T cells to explore whether Galunisertib could enhance CAR T cell function against solid tumor cells. In vitro experiments showed Galunisertib could significantly enhance the specific cytotoxicity of both CD133- and HER2-specific CAR T cells. However, Galunisertib had no direct killing effect on target cells. Galunisertib significantly increased the cytokine secretion of CAR T cells and T cells that do not express CAR (Nontransfected T cells). Galunisertib did not affect the proliferation of T cells, the antigen expression on target cells and CD69 on CAR T cells. We found that TGF-β was secreted by T cells themselves upon activation, and Galunisertib could reduce TGF-β signaling in CAR T cells. Our findings can provide the basis for further preclinical and clinical studies of the combination of Galunisertib and CAR T cells in the treatment of solid tumors.