CAR T cells targeting BAFF-R can overcome CD19 antigen loss in B cell malignancies

Novel and multiple targets for chimeric antigen receptor-based therapies in lymphoma

Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 in B-cell non-Hodgkin lymphoma (NHL) validates the utility of CAR-based therapy for lymphomatous malignancies. Despite the success, treatment failure due to CD19 antigen loss, mutation, or down-regulation remains the main obstacle to cure. On-target, off-tumor effect of CD19-CAR T leads to side effects such as prolonged B-cell aplasia, limiting the application of therapy in indolent diseases such as chronic lymphocytic leukemia (CLL). Alternative CAR targets and multi-specific CAR are potential solutions to improving cellular therapy outcomes in B-NHL. For Hodgkin lymphoma and T-cell lymphoma, several cell surface antigens have been studied as CAR targets, some of which already showed promising results in clinical trials. Some antigens are expressed by different lymphomas and could be used for designing tumor-agnostic CAR. Here, we reviewed the antigens that have been studied for novel CAR-based therapies, as well as CARs designed to target two or more antigens in the treatment of lymphoma.

A State-of-the-Art Review on the Recent Advances of Mesenchymal Stem Cell Therapeutic Application in Systematic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with an unknown etiology that has widespread clinical and immunological manifestations. Despite the increase in knowledge about the pathogenesis process and the increase in treatment options, however, the treatments fail in half of the cases. Therefore, there is still a need for research on new therapies. Mesenchymal stem cells (MSCs) are powerful regulators of the immune system and can reduce the symptoms of systemic lupus erythematosus. This study aimed to review the mechanisms of immune system modulation by MSCs and the role of these cells in the treatment of SLE. MSCs suppress T lymphocytes through various mechanisms, including the production of transforming growth factor-beta (TGF-B), prostaglandin E2 (PGE2), nitric oxide (NO), and indolamine 2 and 3-oxygenase (IDO). In addition, MSCs inhibit the production of their autoantibodies by inhibiting the differentiation of lymphocytes. The production of autoantibodies against nuclear antigens is an important feature of SLE. On the other hand, MSCs inhibit antigen delivery by antigen-presenting cells (APCs) to T lymphocytes. Studies in animal models have shown the effectiveness of these cells in treating SLE. However, few studies have been performed on the effectiveness of this treatment in humans. It can be expected that new treatment strategies for SLE will be introduced in the future, given the promising results of MSCs application.

Novel Biomarkers and Molecular Targets in ALL

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a widely heterogeneous disease in terms of genomic alterations, treatment options, and prognosis. While ALL is considered largely curable in children, adults tend to have higher risk disease subtypes and do not respond as favorably to conventional chemotherapy. Identifying genomic drivers of leukemogenesis and applying targeted therapies in an effort to improve disease outcomes is an exciting focus of current ALL research. Here, we review recent updates in ALL targeted therapy and present promising opportunities for future research.

RECENT FINDINGS

With the utilization of next-generation sequencing techniques, the genomic landscape of ALL has greatly expanded to encompass novel subtypes characterized by recurrent chromosomal rearrangements, gene fusions, sequence mutations, and distinct gene expression profiles. The evolution of small molecule inhibitors and immunotherapies, and the exploration of unique therapy combinations are some examples of recent advancements in the field. Targeted therapies are becoming increasingly important in the treatment landscape of ALL to improve outcomes and minimize toxicity. Significant recent advancements have been made in the detection of susceptible genomic drivers and the use of novel therapies to target them.

Novel chimeric antigen receptor targets and constructs for acute lymphoblastic leukemia: Moving beyond CD19

Acute lymphoblastic leukemia (ALL) is the second most common acute leukemia in adults with a poor prognosis with relapsed or refractory (R/R) B-cell lineage ALL (B-ALL). Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has shown excellent response rates in RR B-ALL, but most patients relapse due to poor persistence of CAR T-cell therapy or other tumor-associated escape mechanisms. In addition, anti-CD19 CAR T-cell therapy causes several serious side effects such as cytokine release syndrome and neurotoxicity. In this review, we will discuss novel CAR targets, CAR constructs, and various strategies to boost CARs for the treatment of RR B-ALL. In addition, we discuss a few novel strategies developed to reduce the side effects of CAR.

Antigen experience history directs distinct functional states of CD8+ CAR T cells during the anti-leukemia response

Chimeric antigen receptor T cells are an effective therapy for B-lineage malignancies. However, many patients relapse and this therapeutic has yet to show strong efficacy in other hematologic or solid tumors. One opportunity for improvement lies in the ability to generate T cells with desirable functional characteristics. Here, we dissect the biology of CD8+ CAR T cells (CAR8) by controlling whether the T cell has encountered cognate TCR antigen prior to CAR generation. We find that prior antigen experience influences multiple aspects of in vitro and in vivo CAR8 functionality, resulting in superior effector function and leukemia clearance in the setting of limiting target antigen density compared to antigen-inexperienced T cells. However, this comes at the expense of inferior proliferative capacity, susceptibility to phenotypic exhaustion and dysfunction, and inability to clear wildtype leukemia in the setting of limiting CAR+ cell dose. Epigenomic and transcriptomic comparisons of these cell populations identified overexpression of the Runx2 transcription factor as a novel strategy to enhance CAR8 function, with a differential impact depending on prior cell state. Collectively, our data demonstrate that prior antigen experience determines functional attributes of a CAR T cell, as well as amenability to functional enhancement by transcription factor modulation.

Safety and efficacy of a novel anti-CD19 chimeric antigen receptor T cell product targeting a membrane-proximal domain of CD19 with fast on- and off-rates against non-Hodgkin lymphoma: a first-in-human study

BACKGROUND

Commercial anti-CD19 chimeric antigen receptor T-cell therapies (CART19) are efficacious against advanced B-cell non-Hodgkin lymphoma (NHL); however, most patients ultimately relapse. Several mechanisms contribute to this failure, including CD19-negative escape and CAR T dysfunction. All four commercial CART19 products utilize the FMC63 single-chain variable fragment (scFv) specific to a CD19 membrane-distal epitope and characterized by slow association (on) and dissociation (off) rates. We hypothesized that a novel anti-CD19 scFv that engages an alternative CD19 membrane-proximal epitope independent of FMC63 and that is characterized by faster on- and off-rates could mitigate CART19 failure and improve clinical efficacy.

METHODS

We developed an autologous CART19 product with 4-1BB co-stimulation using a novel humanized chicken antibody (h1218). This antibody is specific to a membrane-proximal CD19 epitope and harbors faster on/off rates compared to FMC63. We tested h1218-CART19 in vitro and in vivo using FMC63-CART19-resistant models. We conducted a first-in-human multi-center phase I clinical trial to test AT101 (clinical-grade h1218-CART19) in patients with relapsed or refractory (r/r) NHL.

RESULTS

Preclinically, h1218- but not FMC63-CART19 were able to effectively eradicate lymphomas expressing CD19 point mutations (L174V and R163L) or co-expressing FMC63-CAR19 as found in patients relapsing after FMC63-CART19. Furthermore, h1218-CART19 exhibited enhanced killing of B-cell malignancies in vitro and in vivo compared with FMC63-CART19. Mechanistically, we found that h1218-CART19 had reduced activation-induced cell death (AICD) and enhanced expansion compared to FMC63-CART19 owing to faster on- and off-rates. Based on these preclinical results, we performed a phase I dose-escalation trial, testing three dose levels (DL) of AT101 (the GMP version of h1218) using a 3 + 3 design. In 12 treated patients (7 DLBCL, 3 FL, 1 MCL, and 1 MZL), AT101 showed a promising safety profile with 8.3% grade 3 CRS (n = 1) and 8.3% grade 4 ICANS (n = 1). In the whole cohort, the overall response rate was 91.7%, with a complete response rate of 75.0%, which improved to 100% in DL-2 and -3. AT101 expansion correlates with CR and B-cell aplasia.

CONCLUSIONS

We developed a novel, safe, and potent CART19 product that recognizes a membrane-proximal domain of CD19 with fast on- and off-rates and showed significant efficacy and promising safety in patients with relapsed B-cell NHL.

TRIAL REGISTRATION

NCT05338931; Date: 2022-04-01.

Translational development of a novel BAFF-R CAR-T therapy targeting B-cell lymphoid malignancies

Several CD19-targeting CAR-T cells are used to treat leukemias and lymphomas; however, relapsed and/or refractory (R/R) disease is still observed in a significant number of patients. Additionally, the success of CD19-CAR-T cell therapies is not uniform across hematological malignancies, particularly in chronic lymphocytic leukemia (CLL). In this study, we present the development of a novel CAR-T cell therapy targeting B-cell activating factor receptor (BAFF-R), a key regulator of B-cell proliferation and maturation. A new monoclonal antibody against BAFF-R was generated from a hybridoma clone and used to create a novel MC10029 CAR construct. Through a series of in vitro and in vivo models using the Nalm-6 cell line for leukemia and the Z138 cell line for lymphoma, we demonstrated the antigen-specific cytotoxicity of MC10029 CAR-T cells against tumor cells. Additionally, MC10029 CAR-T cells exhibited potent antitumor effects against CD19 knockout tumor cells, mimicking CD19-negative R/R disease. MC10029 CAR-T cells were specifically targeted to CLL, in which BAFF-R is nearly always expressed. The cytotoxicity of MC10029 CAR-T cells was first shown in the MEC-1 CLL cell line, before we turned our efforts to subject-derived samples. Using healthy donor-engineered MC10029 CAR-T cells against enriched primary tumor cells, followed by subject-derived MC10029 CAR-T cells against autologous tumor cells, we showed the efficacy of MC10029 CAR-T cells against CLL subject samples. With these robust data, we have advanced to the production of MC10029 CAR-T cells, using GMP lentivirus, and obtained an IND approval in preparation for a Phase 1 clinical trial.

CD38-Specific CAR Integrated into CD38 Locus Driven by Different Promoters Causes Distinct Antitumor Activities of T and NK Cells

The robust and stable expression of CD38 in T-cell acute lymphoblastic leukemia (T-ALL) blasts makes CD38 chimeric antigen receptor (CAR)-T/natural killer (NK) a potential therapy for T-ALL. However, CD38 expression in normal T/NK cells causes fratricide of CD38 CAR-T/NK cells. Here a "2-in-1" gene editing strategy is developed to generate fratricide-resistant locus-specific CAR-T/NK cells. CD38-specific CAR is integrated into the disrupted CD38 locus by CRISPR/Cas9, and CAR is placed under the control of either endogenous CD38 promoter (CD38KO/KI ) or exogenous EF1α promoter (CD38KO/KI EF1α). CD38 knockout reduces fratricide and allows the expansion of CAR-T cells. Meanwhile, CD38KO/KI EF1α results in higher CAR expression than CD38KO/KI in both CAR-T and CAR-NK cells. In a mouse T-ALL model, CD38KO/KI EF1α CAR-T cells eradicate tumors better than CD38KO/KI CAR-T cells. Surprisingly, CD38KO/KI CAR-NK cells show superior tumor control than CD38KO/KI EF1α CAR-NK cells. Further investigation reveals that endogenous regulatory elements in NK cells lead to higher expression of CD38 CAR than in T cells, and the expression levels of CAR affect the therapeutic outcome of CAR-T and CAR-NK cells differently. Therefore, these results support the efficacy of CD38 CAR-T/NK against T-ALL and demonstrate that the "2-in-1" strategy can resolve fratricide and enhance tumor eradication, paving the way for clinical translation.

Thinking "outside the germinal center": Re-educating T cells to combat follicular lymphoma

There have been significant advancements in the management of follicular lymphoma (FL), the most common indolent lymphoma. These include immunomodulatory agents such as lenalidomide, epigenetic modifiers (tazemetostat), and phosphoinotiside-3 kinase inhibitors (copanlisib). The focus of this review is T cell-engager therapies, namely chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies, have recently transformed the treatment landscape of FL. Two CAR T cell products, axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel), and one bispecific antibody, mosunetuzumab, recently received FDA approvals in FL. Several other new immune effector drugs are being evaluated and will expand the treatment armamentarium. This review focuses on CAR T-cell and bispecific antibody therapies, details their safety and efficacy and considers their evolving role in the current treatment landscape of FL.

Beyond Bruton's tyrosine kinase inhibitors in mantle cell lymphoma: bispecific antibodies, antibody-drug conjugates, CAR T-cells, and novel agents

Mantle cell lymphoma is a B cell non-Hodgkin lymphoma (NHL), representing 2-6% of all NHLs and characterized by overexpression of cyclin D1. The last decade has seen the development of many novel treatment approaches in MCL, most notably the class of Bruton's tyrosine kinase inhibitors (BTKi). BTKi has shown excellent outcomes for patients with relapsed or refractory MCL and is now being studied in the first-line setting. However, patients eventually progress on BTKi due to the development of resistance. Additionally, there is an alteration in the tumor microenvironment in these patients with varying biological and therapeutic implications. Hence, it is necessary to explore novel therapeutic strategies that can be effective in those who progressed on BTKi or potentially circumvent resistance. In this review, we provide a brief overview of BTKi, then discuss the various mechanisms of BTK resistance including the role of genetic alteration, cancer stem cells, tumor microenvironment, and adaptive reprogramming bypassing the effect of BTK inhibition, and then provide a comprehensive review of current and emerging therapeutic options beyond BTKi including novel agents, CAR T cells, bispecific antibodies, and antibody-drug conjugates.

Tumor-intrinsic sensitivity to the pro-apoptotic effects of IFN-γ is a major determinant of CD4+ CAR T-cell antitumor activity

CD4⁺ T cells and CD4⁺ chimeric antigen receptor (CAR) T cells display highly variable antitumor activity in preclinical models and in patients; however, the mechanisms dictating how and when CD4⁺ T cells promote tumor regression are incompletely understood. With the help of functional intravital imaging, we report that interferon (IFN)-γ production but not perforin-mediated cytotoxicity was the dominant mechanism for tumor elimination by anti-CD19 CD4⁺ CAR T cells. Mechanistically, mouse or human CD4⁺ CAR T-cell-derived IFN-γ diffused extensively to act on tumor cells at distance selectively killing tumors sensitive to cytokine-induced apoptosis, including antigen-negative variants. In anti-CD19 CAR T-cell-treated patients exhibiting elevated CAR CD4:CD8 ratios, strong induction of serum IFN-γ was associated with increased survival. We propose that the sensitivity of tumor cells to the pro-apoptotic activity of IFN-γ is a major determinant of CD4⁺ CAR T-cell efficacy and may be considered to guide the use of CD4⁺ T cells during immunotherapy.

Targeting FLT3-specific chimeric antigen receptor T cells for acute lymphoblastic leukemia with KMT2A rearrangement

CD19-specific chimeric antigen receptor T (CAR T) immunotherapy is used to treat B-cell malignancies. However, antigen-escape mediated relapse following CAR T therapy has emerged as a major concern. In some relapsed cases, especially KMT2A rearrangement-positive B-acute lymphoblastic leukemia (KMT2A-r B-ALL), most of the B-cell antigens are lost via lineage conversion to the myeloid phenotype, rendering multi-B-cell-antigen-targeted CAR T cell therapy ineffective. Fms-related tyrosine kinase-3 (FLT3) is highly expressed in KMT2A-r B-ALL; therefore, in this study, we aimed to evaluate the antitumor efficacy of CAR T cells targeting both CD19 and FLT3 in KMT2A-r B-ALL cells. We developed piggyBac transposon-mediated CAR T cells targeting CD19, FLT3, or both (dual) and generated CD19-negative KMT2A-r B-ALL models through CRISPR-induced CD19 gene-knockout (KO). FLT3 CAR T cells showed antitumor efficacy against CD19-KO KMT2A-r B-ALL cells both in vitro and in vivo; dual-targeted CAR T cells showed cytotoxicity against wild-type (WT) and CD19-KO KMT2A-r B-ALL cells, whereas CD19 CAR T cells demonstrated cytotoxicity only against WT KMT2A-r B-ALL cells in vitro. Therefore, targeting FLT3-specific CAR T cells would be a promising strategy for KMT2A-r B-ALL cells even with CD19-negative relapsed cases.

Sequencing antigen-targeting antibodies and cellular therapies in adults with relapsed/refractory B-cell acute lymphoblastic leukemia

The recent approvals of four CD19-or CD22-targeted therapies for B-cell acute lymphoblastic leukemia (B-ALL) have transformed the treatment of relapsed/refractory (r/r) disease. Adults with r/r B-ALL are usually eligible for all options, but there are no studies directly comparing these agents, and the treating physician must decide which to select. Each therapy has notable activity as a single agent but has limitations in particular settings, and the optimal choice varies. These therapies can be complementary and used either sequentially or concomitantly. Here, we review the current landscape of antigen-targeted therapies for r/r B-ALL and discuss considerations for their use.

Generation of a humanized afucosylated BAFF-R antibody with broad activity against human B-cell malignancies

B-cell activating factor receptor (BAFF-R) is a mature B-cell survival receptor, which is highly expressed in a wide variety of B-cell malignancies but with minimal expression in immature B cells. These properties make BAFF-R an attractive target for therapy of B-cell lymphomas. We generated a novel humanized anti BAFF-R monoclonal antibody (mAb) with high specificity and potent in vitro and in vivo activity against B-cell lymphomas and leukemias. The humanized variants of an original chimeric BAFF-R mAb retained BAFF-R binding affinity and antibody-dependent cellular cytotoxicity (ADCC) against a panel of human cell lines and primary lymphoma samples. Furthermore, 1 humanized BAFF-R mAb clone and its afucosylated version, glycoengineered to optimize the primary mechanism of action, prolonged survival of immunodeficient mice bearing human tumor cell lines or patient-derived lymphoma xenografts in 3 separate models, compared with controls. Finally, the tissue specificity of this humanized mAb was confirmed against a broad panel of normal human tissues. Taken together, we have identified a robust lead-candidate BAFF-R mAb for clinical development.

Cellular Therapies in Chronic Lymphocytic Leukemia and Richter’s Transformation: Recent Developments in Chimeric Antigen Receptor T-Cells, Natural Killer Cells, and Allogeneic Stem Cell Transplant

Cellular therapies can be viewed as both the newest and oldest techniques for treating chronic lymphocytic leukemia (CLL) and Richter’s transformation (RT). On one hand, allogeneic hematopoietic stem cell transplantation (alloHSCT) has been available for decades, though its use is diminishing with the increasing availability of effective novel targeted agents, especially in CLL. Among newer techniques, chimeric antigen receptor T-cells (CAR-T) have demonstrated astounding efficacy in several hematologic malignancies, leading to FDA approval and use in clinical practice. However, though CLL is the earliest disease type for which CAR-T were studied, development has been slower and has yet to lead to regulatory approval. Owing partially to its rarity but also due to the aggressive behavior of RT, CAR-T in RT have only been minimally explored. Here, we will focus on the applications of cellular therapies in CLL and RT, specifically reviewing more recent data related to alloHSCT in the novel-agent era and CAR-T cell development in CLL/RT, focusing on safety and efficacy successes and limitations. We will review strategies to improve upon CAR-T efficacy and discuss ongoing trials utilizing CAR-T in CLL/RT, as well as emerging technologies, such as allogeneic CAR-T and natural killer CAR (CAR NK) cells.

Endothelial cell-leukemia interactions remodel drug responses, uncovering T-ALL vulnerabilities

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive and often incurable disease. To uncover therapeutic vulnerabilities, we first developed T-ALL patient-derived tumor xenografts (PDXs) and exposed PDX cells to a library of 433 clinical-stage compounds in vitro. We identified 39 broadly active drugs with antileukemia activity. Because endothelial cells (ECs) can alter drug responses in T-ALL, we developed an EC/T-ALL coculture system. We found that ECs provide protumorigenic signals and mitigate drug responses in T-ALL PDXs. Whereas ECs broadly rescued several compounds in most models, for some drugs the rescue was restricted to individual PDXs, suggesting unique crosstalk interactions and/or intrinsic tumor features. Mechanistically, cocultured T-ALL cells and ECs underwent bidirectional transcriptomic changes at the single-cell level, highlighting distinct "education signatures." These changes were linked to bidirectional regulation of multiple pathways in T-ALL cells as well as in ECs. Remarkably, in vitro EC-educated T-ALL cells transcriptionally mirrored ex vivo splenic T-ALL at single-cell resolution. Last, 5 effective drugs from the 2 drug screenings were tested in vivo and shown to effectively delay tumor growth and dissemination thus prolonging overall survival. In sum, we developed a T-ALL/EC platform that elucidated leukemia-microenvironment interactions and identified effective compounds and therapeutic vulnerabilities.

A systematic review and meta-analysis of CD22 CAR T-cells alone or in combination with CD19 CAR T-cells

Chimeric antigen receptor (CAR) T-cells are an emerging therapy for the treatment of relapsed/refractory B-cell malignancies. While CD19 CAR-T cells have been FDA-approved, CAR T-cells targeting CD22, as well as dual-targeting CD19/CD22 CAR T-cells, are currently being evaluated in clinical trials. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of CD22-targeting CAR T-cell therapies. We searched MEDLINE, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials from inception to March 3rd 2022 for full-length articles and conference abstracts of clinical trials employing CD22-targeting CAR T-cells in acute lymphocytic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). The primary outcome was best complete response (bCR). A DerSimonian and Laird random-effects model with arcsine transformation was used to pool outcome proportions. From 1068 references screened, 100 were included, representing 30 early phase studies with 637 patients, investigating CD22 or CD19/CD22 CAR T-cells. CD22 CAR T-cells had a bCR of 68% [95% CI, 53-81%] in ALL (n= 116), and 64% [95% CI, 46-81%] in NHL (n= 28) with 74% and 96% of patients having received anti-CD19 CAR T-cells previously in ALL and NHL studies respectively. CD19/CD22 CAR T-cells had a bCR rate of 90% [95% CI, 84-95%] in ALL (n= 297) and 47% [95% CI, 34-61%] in NHL (n= 137). The estimated incidence of total and severe (grade ≥3) CRS were 87% [95% CI, 80-92%] and 6% [95% CI, 3-9%] respectively. ICANS and severe ICANS had an estimated incidence of 16% [95% CI, 9-25%] and 3% [95% CI, 1-5%] respectively. Early phase trials of CD22 and CD19/CD22 CAR T-cells show high remission rates in ALL and NHL. Severe CRS or ICANS were (1)rare and dual-targeting did not increase toxicity. Variability in CAR construct, dose, and patient factors amongst studies limits comparisons, with long-term outcomes yet to be reported.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42020193027.

Chimeric Antigen Receptor T-cell Therapy: Current Status and Clinical Outcomes in Pediatric Hematologic Malignancies

Chimeric antigen receptor T-cell (CART) therapy has transformed the treatment paradigm for pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL), with complete remission rates in key pivotal CD19-CART trials ranging from 65% to 90%. Alongside this new therapy, new toxicity profiles and treatment limitations have emerged, necessitating toxicity consensus grading systems, cooperative group trials, and novel management approaches. This review highlights the results of key clinical trials of CART for pediatric hematologic malignancies, discusses the most common toxicities seen to date, and elucidates challenges, opportunities, and areas of active research to optimize this therapy.

Chimeric Antigen Receptor (CAR)-T Cell Immunotherapy Against Thoracic Malignancies: Challenges and Opportunities

Different from surgery, chemical therapy, radio-therapy and target therapy, Chimeric antigen receptor-modified T (CAR-T) cells, a novel adoptive immunotherapy strategy, have been used successfully against both hematological tumors and solid tumors. Although several problems have reduced engineered CAR-T cell therapeutic outcomes in clinical trials for the treatment of thoracic malignancies, including the lack of specific antigens, an immunosuppressive tumor microenvironment, a low level of CAR-T cell infiltration into tumor tissues, off-target toxicity, and other safety issues, CAR-T cell treatment is still full of bright future. In this review, we outline the basic structure and characteristics of CAR-T cells among different period, summarize the common tumor-associated antigens in clinical trials of CAR-T cell therapy for thoracic malignancies, and point out the current challenges and new strategies, aiming to provide new ideas and approaches for preclinical experiments and clinical trials of CAR-T cell therapy for thoracic malignancies.

Immunotherapy for Pediatric Acute Lymphoblastic Leukemia: Recent Advances and Future Perspectives

Pediatric acute lymphoblastic leukemia (ALL) is the most common subtype of childhood leukemia, which is characterized by the abnormal proliferation and accumulation of immature lymphoid cell in the bone marrow. Although the long-term survival rate for pediatric ALL has made significant progress over years with the development of contemporary therapeutic regimens, patients are still suffered from relapse, leading to an unsatisfactory outcome. Since the immune system played an important role in the progression and relapse of ALL, immunotherapy including bispecific T-cell engagers and chimeric antigen receptor T cells has been demonstrated to be capable of enhancing the immune response in pediatric patients with refractory or relapsed B-cell ALL, and improving the cure rate of the disease and patients’ quality of life, thus receiving the authorization for market. Nevertheless, the resistance and toxicities associated with the current immunotherapy remains a huge challenge. Novel therapeutic options to overcome the above disadvantages should be further explored. In this review, we will thoroughly discuss the emerging immunotherapeutics for the treatment of pediatric ALL, as well as side-effects and new development.

CAR-T Cells Shoot for New Targets: Novel Approaches to Boost Adoptive Cell Therapy for B Cell-Derived Malignancies

Chimeric antigen receptor (CAR)-T cell therapy is undeniably a promising tool in combating various types of hematological malignancies. However, it is not yet optimal and a significant number of patients experience a lack of response or relapse after the treatment. Therapy improvement requires careful analysis of the occurring problems and a deeper understanding of the reasons that stand behind them. In this review, we summarize the recent knowledge about CAR-T products' clinical performance and discuss diversified approaches taken to improve the major shortcomings of this therapy. Especially, we prioritize the challenges faced by CD19 CAR-T cell-based treatment of B cell-derived malignancies and revise the latest insights about mechanisms mediating therapy resistance. Since the loss of CD19 is one of the major obstacles to the success of CAR-T cell therapy, we present antigens that could be alternatively used for the treatment of various types of B cell-derived cancers.

CD19/BAFF-R dual-targeted CAR T cells for the treatment of mixed antigen-negative variants of acute lymphoblastic leukemia

Chimeric antigen receptor (CAR) T cells targeting CD19 mediate potent antitumor effects in B-cell malignancies including acute lymphoblastic leukemia (ALL), but antigen loss remains the major cause of treatment failure. To mitigate antigen escape and potentially improve the durability of remission, we developed a dual-targeting approach using an optimized, bispecific CAR construct that targets both CD19 and BAFF-R. CD19/BAFF-R dual CAR T cells exhibited antigen-specific cytokine release, degranulation, and cytotoxicity against both CD19-/- and BAFF-R-/- variant human ALL cells in vitro. Immunodeficient mice engrafted with mixed CD19-/- and BAFF-R-/- variant ALL cells and treated with a single dose of CD19/BAFF-R dual CAR T cells experienced complete eradication of both CD19-/- and BAFF-R-/- ALL variants, whereas mice treated with monospecific CD19 or BAFF-R CAR T cells succumbed to outgrowths of CD19-/BAFF-R+ or CD19+/BAFF-R- tumors, respectively. Further, CD19/BAFF-R dual CAR T cells showed prolonged in vivo persistence, raising the possibility that these cells may have the potential to promote durable remissions. Together, our data support clinical translation of BAFF-R/CD19 dual CAR T cells to treat ALL.

CAR-T Cells Targeting TSHR Demonstrate Safety and Potent Preclinical Activity Against Differentiated Thyroid Cancer

BACKGROUND

Chimeric antigen receptor T cells (CAR-Ts) have demonstrated remarkable efficacy in hematological cancers but have not yet translated in treating solid tumors. The significant hurdles limiting CAR-T therapy were from a paucity of differentially expressed cell surface molecules on solid tumors that can be safely targeted. Here, we present TSH receptor (TSHR) as a putative target for CAR-T therapy of differentiated thyroid cancer (DTC).

METHODS

We undertook a large-scale screen on thyroid cancer tissues and multiple internal organs through bioinformatical analysis and immunohistochemistry to date TSHR expression. Using 3 previously described monoclonal antibodies, we generated 3 third-generation CAR-Ts. We tested anti-TSHR CAR-T in vitro activity by T-cell function and killing assay. Then we tested preclinical therapeutical efficacy in a xenograft mouse model of DTC and analyzed mice's physical conditions and histological abnormalities to evaluate anti-TSHR CAR-T's safety.

RESULTS

TSHR is highly and homogeneously expressed on 90.8% (138/152) of papillary thyroid cancer, 89.2% (33/37) of follicular thyroid cancer, 78.2% (18/23) of cervical lymph node metastases, and 86.7% of radioactive iodine resistance diseases. We developed 3 novel anti-TSHR CAR-Ts from monoclonal antibodies M22, K1-18, and K1-70; all 3 CAR-Ts mediate significant antitumor activity in vitro. Among these, we demonstrate that K1-70 CAR-T can have therapeutical efficacy in vivo, and no apparent toxicity has been observed.

CONCLUSION

TSHR is a latent target antigen of CAR-T therapy for DTC. Anti-TSHR CAR-T could represent a therapeutic option for patients with locoregional relapsed or distant metastases of thyroid cancer and should be tested in carefully designed clinical trials.

Resistance and recurrence of malignancies after CAR-T cell therapy

The emergence of chimeric antigen receptor T (CAR-T) cell therapy has ushered a new era in cancer therapy, especially the treatment of hematological malignancies. However, resistance and recurrence still occur in some patients after CAR-T cell treatment. CAR-T cell inefficiency and tumor escape have emerged as the main challenges for the long-term disease control of B cell malignancies by this promising immunotherapy. In solid tumor treatment, CAR-T cells must also overcome many hurdles from the tumor or immune-suppressed tumor environment, which have become obstacles to the advancement of CAR-T therapy. Therefore, an understanding of the mechanisms underlying post-CAR treatment failure in patients is necessary. In this review, we characterize some mechanisms of resistance and recurrence after CAR-T cell therapy and correspondingly suggest reasonable treatment strategies.

A BAFF ligand-based CAR-T cell targeting three receptors and multiple B cell cancers

B cell-activating factor (BAFF) binds the three receptors BAFF-R, BCMA, and TACI, predominantly expressed on mature B cells. Almost all B cell cancers are reported to express at least one of these receptors. Here we develop a BAFF ligand-based chimeric antigen receptor (CAR) and generate BAFF CAR-T cells using a non-viral gene delivery method. We show that BAFF CAR-T cells bind specifically to each of the three BAFF receptors and are effective at killing multiple B cell cancers, including mantle cell lymphoma (MCL), multiple myeloma (MM), and acute lymphoblastic leukemia (ALL), in vitro and in vivo using different xenograft models. Co-culture of BAFF CAR-T cells with these tumor cells results in induction of activation marker CD69, degranulation marker CD107a, and multiple proinflammatory cytokines. In summary, we report a ligand-based BAFF CAR-T capable of binding three different receptors, minimizing the potential for antigen escape in the treatment of B cell cancers.

Nanomedicines in B cell-targeting therapies

B cells play multiple roles in immune responses related to autoimmune diseases as well as different types of cancers. As such, strategies focused on B cell targeting attracted wide interest and developed intensively. There are several common mechanisms various B cell targeting therapies have relied on, including direct B cell depletion, modulation of B cell antigen receptor (BCR) signaling, targeting B cell survival factors, targeting the B cell and T cell costimulation, and immune checkpoint blockade. Nanocarriers, used as drug delivery vehicles, possess numerous advantages to low molecular weight drugs, reducing drug toxicity, enhancing blood circulation time, as well as augmenting targeting efficacy and improving therapeutic effect. Herein, we review the commonly used targets involved in B cell targeting approaches and the utilization of various nanocarriers as B cell-targeted delivery vehicles. STATEMENT OF SIGNIFICANCE: As B cells are engaged significantly in the development of many kinds of diseases, utilization of nanomedicines in B cell depletion therapies have been rapidly developed. Although numerous studies focused on B cell targeting have already been done, there are still various potential receptors awaiting further investigation. This review summarizes the most relevant studies that utilized nanotechnologies associated with different B cell depletion approaches, providing a useful tool for selection of receptors, agents and/or nanocarriers matching specific diseases. Along with uncovering new targets in the function map of B cells, there will be a growing number of candidates that can benefit from nanoscale drug delivery.

Relapse Mechanism and Treatment Strategy After Chimeric Antigen Receptor T-Cell Therapy in Treating B-Cell Hematological Malignancies

Over the past few decades, immunotherapy has revolutionized the modern medical oncology field. Chimeric antigen receptor (CAR)-T cell therapy has a promising curative effect in the treatment of hematological malignancies. Anti-CD19 CAR-T cells are the most mature CAR-T cells recently studied and in recent years it has achieved a complete remission rate of approximately 90% in the treatment of B-cell acute lymphoblastic leukemia (B-ALL). Although CAR-T cell therapy has greatly alleviated the disease in patients with leukemia or lymphoma, some of them still relapse after treatment. Therefore, in this article, we discuss the factors that may contribute to disease relapse following CAR-T cell therapy and summarize potential strategies to overcome these obstacles, thus providing the possibility of improving standard treatment regimens.

Will immunotherapy lead to a breakthrough in the treatment of older adults with ALL?

Historically, older adults with B-cell acute lymphoblastic leukemia (ALL) have done poorly with chemotherapy-based treatment. Therefore, new innovative approaches are urgently needed to improve outcomes for this population. CD19-targeted immunotherapies such as blinatumomab and chimeric antigen receptor (CAR) T cell therapy have produced remarkable responses in relapsed/refractory (r/r) B-cell ALL, including clearance of minimal residual disease (MRD). Available data support the efficacy and safety of blinatumomab in older adults with advanced B-cell ALL. Therefore, its application is being extended to frontline regimens for B-cell ALL, particularly in older adults. There are several studies actively examining the role of blinatumomab alone or in combination with attenuated dosing of conventional chemotherapy or novel agents in older adults with newly diagnosed ALL and early data are encouraging. While CD19-targeted CAR (CD19CAR) T cell therapy is active in children and young adults with r/r B-cell ALL, data supporting its efficacy and safety in older adults with ALL is scarce. Furthermore, the commercially FDA approved CD19CAR T cell therapy product for r/r ALL is restricted only to patients ≤25 years of age. Although there are concerns about older adults tolerating the expected toxicities associated with CAR T cell therapy, which may be life threatening, tailored approaches for prophylactic and pre-emptive interventions combined with utilization of safer CAR T cell platforms may improve tolerability and further extend the use of this promising treatment to older patients with ALL. In this review, we will discuss the progress in immunotherapies for older adults with B-cell ALL and their potential for transforming frontline therapy for newly diagnosed patients.

Cellular Therapy Updates in B-Cell Lymphoma: The State of the CAR-T

Simple Summary

B-cell lymphomas are the most commonly occurring blood cancer and the second leading cause of cancer-related death among blood cancers. Chemotherapy and stem cell transplantation have long served as the standard therapies for relapsed or refractory aggressive B-cell lymphomas with very poor survival, historically. Recently, the development of multiple chimeric antigen receptor T-cell (CAR-T) products has translated into dramatically improved outcomes and survival for patients with relapsed or refractory B-cell lymphoma. Meanwhile, basic, translational and clinical development within the field has progressed rapidly. The aim of this review is to summarize the current state of the art of CAR-T therapies for B-cell lymphomas within this rapidly evolving field, focusing on current United States Food and Drug Administration (US FDA)-approved products and a selection of promising areas of future clinical development.

Abstract

Non-Hodgkin Lymphoma accounts for >460,000 cases and >240,000 deaths globally and >77,000 cases and >20,000 deaths in the U.S. annually, with ~85% of cases being B-cell malignancies. Until recently, patients with relapsed/refractory B-cell lymphoma following standard chemotherapy in combination with anti-CD20 monoclonal antibodies and autologous stem cell transplantation experienced a median overall survival (OS) of <6 months. However, with the approval of four different CD-19 CAR-T therapies between 2017 and 2021, approximately 60–80% of patients receiving CAR-T therapy now achieve an objective response with >3 years median OS. Here, we review the current state of the art of CD19 CAR-T therapies for B-cell lymphomas, focusing on current updates in US FDA-approved products, along with their associated efficacy and toxicities. Lastly, we highlight a selection of promising clinical developments in the field, including various novel strategies to increase CAR-T therapy efficacy while mitigating toxicity.

Driving Out Chronic Lymphocytic Leukemia With CAR T Cells

Chronic lymphocytic leukemia (CLL) is the most prevalent leukemia in the Western hemisphere. The recent availability of novel targeted therapies, namely Bruton's tyrosine kinase, phosphoinositide-3 kinase, and BCL-2 inhibitors, have revolutionized the treatment algorithm for CLL but have not yet resulted in cure. Advances in the field of immuno-oncology and T cell engineering brought chimeric antigen receptor (CAR) T cell therapy from the laboratory to the clinic for treatment of B cell lymphoid malignancies and has improved the disease response and survival outcomes of various types of relapsed and/or refractory B cell lymphomas. While acknowledging that there are no approved CAR T cell therapies for CLL at this time, in this comprehensive review we explore novel targets for CAR T cell therapy in CLL and highlight the promising results of CAR T cell trials reported to date. Furthermore, we shed light on future areas of development, including multitarget CAR T cell products for this disease.

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.

Antibody and cellular immunotherapies for acute lymphoblastic leukemia in adults

Despite improvements in the outcomes of patients with acute lymphoblastic leukemia (ALL), traditional therapies (including hematopoietic stem cell transplant) often still fail. Antigen-specific immunotherapies for the treatment of ALL such as monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engagers (BiTEs), and chimeric antigen receptor (CAR) T-cells have demonstrated remarkable clinical efficacy and are rapidly evolving. With indisputable activity in patients with relapsed or refractory ALL, efforts now hope to integrate these agents into earlier phases of treatment. In this review, we will discuss the available antibody and cellular-based immunotherapies for the treatment of patients with ALL and provide a clinical and biologic framework with which to inform treatment approaches.

Surface Proteomics Reveals CD72 as a Target for In Vitro-Evolved Nanobody-Based CAR-T Cells in KMT2A/MLL1-Rearranged B-ALL

Alternative strategies are needed for patients with B-cell malignancy relapsing after CD19-targeted immunotherapy. Here, cell surface proteomics revealed CD72 as an optimal target for poor-prognosis KMT2A/MLL1-rearranged (MLLr) B-cell acute lymphoblastic leukemia (B-ALL), which we further found to be expressed in other B-cell malignancies. Using a recently described, fully in vitro system, we selected synthetic CD72-specific nanobodies, incorporated them into chimeric antigen receptors (CAR), and demonstrated robust activity against B-cell malignancy models, including CD19 loss. Taking advantage of the role of CD72 in inhibiting B-cell receptor signaling, we found that SHIP1 inhibition increased CD72 surface density. We establish that CD72-nanobody CAR-T cells are a promising therapy for MLLr B-ALL. SIGNIFICANCE: Patients with MLLr B-ALL have poor prognoses despite recent immunotherapy advances. Here, surface proteomics identifies CD72 as being enriched on MLLr B-ALL but also widely expressed across B-cell cancers. We show that a recently described, fully in vitro nanobody platform generates binders highly active in CAR-T cells and demonstrate its broad applicability for immunotherapy development.This article is highlighted in the In This Issue feature, p. 1861.

Advances in chimeric antigen receptor T-cell therapy for B-cell non-Hodgkin lymphoma

B-cell non-Hodgkin lymphoma (B-NHL) is a group of heterogeneous disease which remains incurable despite developments of standard chemotherapy regimens and new therapeutic agents in decades. Some individuals could have promising response to standard therapy while others are unresponsive to standard chemotherapy or relapse after autologous hematopoietic stem-cell transplantation (ASCT), which indicates the necessity to develop novel therapies for refractory or relapsed B-NHLs. In recent years, a novel cell therapy, chimeric antigen receptor T-cell therapy (CAR-T), was invented to overcome the limitation of traditional treatments. Patients with aggressive B-NHL are considered for CAR-T cell therapy when they have progressive lymphoma after second-line chemotherapy, relapse after ASCT, or require a third-line therapy. Clinical trials of anti-CD19 CAR-T cell therapy have manifested encouraging efficacy in refractory or relapsed B-NHL. However, adverse effects of this cellular therapy including cytokine release syndrome, neurotoxicity, tumor lysis syndrome and on-target, off-tumor toxicities should attract our enough attention despite the great anti-tumor effects of CAR-T cell therapy. Although CAR-T cell therapy has shown remarkable results in patients with B-NHL, the outcomes of patients with B-NHL were inferior to patients with acute lymphoblastic leukemia. The inferior response rate may be associated with physical barrier of lymphoma, tumor microenvironment and low quality of CAR-T cells manufactured from B-NHL patients. Besides, some patients relapsed after anti-CD19 CAR-T cell therapy, which possibly were due to limited CAR-T cells persistence, CD19 antigen escape or antigen down-regulation. Quite a few new antigen-targeted CAR-T products and new-generation CAR-T, for example, CD20-targeted CAR-T, CD79b-targeted CAR-T, CD37-targeted CAR-T, multi-antigen-targeted CAR-T, armored CAR-T and four-generation CAR-T are developing rapidly to figure out these deficiencies.

In Like a Lamb; Out Like a Lion: Marching CAR T Cells Toward Enhanced Efficacy in B-ALL

Combining synthetic biology with adoptive T-cell transfer has led to promising advances in the treatment of relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL), diffuse large B-cell lymphoma (DLBCL), and mantle cell lymphoma (MCL). Chimeric antigen receptors (CARs) are synthetic receptors that redirect T-cell specificity against cancer. CARs include "built-in" signaling domains that reprogram T-cell metabolism, enhance effector function, and support long-term persistence. Despite their success in blood-based malignancies, relapse can occur in CD19-redirected CAR T-cell therapies for several reasons, including poor engraftment, impaired in vivo proliferation, and T-cell senescence. Herein, we explain how subtle alterations in CAR design may overcome barriers to effective adoptive immunotherapy. We also discuss how the physiochemical properties of the single-chain variable fragment (scFv) affect differentiation and persistence. Moreover, we describe innovative advances in CAR engineering and provide insight into the development of humanized scFvs whose proposed benefits include increased persistence and improved clinical outcomes. Tumor cells can evade CAR T-cell-mediated detection and elimination due to the emergence or presence of CD19-negative leukemic cell subpopulations. We also discuss the opportunities and challenges in targeting other B-ALL-associated antigens. Identifying alternate targets is fundamentally necessary to restore the success of CAR T-cell therapies in CD19-negative patients with B-ALL.

Advances in chimeric antigen receptor T cells.Curr Opin Hematol. 2020;27:368-377. [PMID: 32925186 DOI: 10.1097/MOH.0000000000000614]

PURPOSE OF REVIEW

To discuss the important advances in CAR T cell therapy over the past year, focusing on clinical results where available.

RECENT FINDINGS

Approximately 30 years after they were first conceived of and 15 years after the first small-scale single-center clinical trials, the past 3 years represent a major milestone in the development of CAR T cells. In the United States, the Food and Drug Administration (FDA) approved Tisagenlecleucel for the treatment of relapsed/refractory B-ALL and Axicabtagene Ciloleucel, for adults with relapsed/refractory diffuse large B cell lymphoma (R/R DLBCL) in 2017. Tisagenlecleucel received a second indication in adults with R/R DLBCL in 2018. Regulatory approval for CAR T cells was then granted in Europe, Canada, Australia, and Japan. Most recently, in July 2020 the FDA granted regulatory approval to a third CAR T cell product, Brexucabtagene Autoleucel for mantle cell lymphoma. All products target the CD19 antigen but differ in the costimulatory molecule within the CAR construct. Currently, it is unknown whether there are any differences in clinical activity or toxicity between these products.

SUMMARY

The CAR T cell the platform is evolving at a rapid pace and is expected to further improve the therapeutic outcomes of hematological malignancies.

Beyond the storm - subacute toxicities and late effects in children receiving CAR T cells

As clinical advances with chimeric antigen receptor (CAR) T cells are increasingly described and the potential for extending their therapeutic benefit grows, optimizing the implementation of this therapeutic modality is imperative. The recognition and management of cytokine release syndrome (CRS) marked a milestone in this field; however, beyond the understanding gained in treating CRS, a host of additional toxicities and/or potential late effects of CAR T cell therapy warrant further investigation. A multicentre initiative involving experts in paediatric cell therapy, supportive care and/or study of late effects from cancer and haematopoietic stem cell transplantation was convened to facilitate the comprehensive study of extended CAR T cell-mediated toxicities and establish a framework for new systematic investigations of CAR T cell-related adverse events. Together, this group identified six key focus areas: extended monitoring of neurotoxicity and neurocognitive function, psychosocial considerations, infection and immune reconstitution, other end organ toxicities, evaluation of subsequent neoplasms, and strategies to optimize remission durability. Herein, we present the current understanding, gaps in knowledge and future directions of research addressing these CAR T cell-related outcomes. This systematic framework to study extended toxicities and optimization strategies will facilitate the translation of acquired experience and knowledge for optimal application of CAR T cell therapies.

TriBAFF-CAR-T cells eliminate B-cell malignancies with BAFFR-expression and CD19 antigen loss

Background

To investigate the effect of TriBAFF-CAR-T cells on hematological tumor cells.

Methods

TriBAFF-CAR-T and CD19-CAR-T cells were co-cultured with BAFFR-bearing B-cell malignancies at different effector/target ratios to evaluate the anti-tumor effects. In vivo, TriBAFF-CAR-T and CD19-CAR-T cells were intravenously injected into Raji-luciferase xenograft mice. CD19 antigens losing lymphoblasts was simulated by Raji knocking out CD19 (CD19^KO) to investigate the effect of TriBAFF-CAR-T cells on CD19^KO Raji.

Results

Both TriBAFF-CAR-T and CD19-CAR-T cells significantly induced the lysis of Raji, BALL-1, and Jeko-1. Moreover, when CD19-CAR-T cells specifically caused the lysis of K562 with overexpressed CD19, the lethal effect of TriBAFF-CAR-T cells was also specific for BAFFR-bearing K562 with increasing levels of interleukin-2 and INF-γ. The TriBAFF-CAR-T have the same effect with CD19-CAR-T cells in treating Raji xenofraft mice. TriBAFF-CAR-T cells also have great effect in CD19^KO Raji cells.

Conclusions

In this study, we successfully constructed novel TriBAFF-CAR-T cells to eliminate BAFFR-bearing and CD19 antigen loss in hematological tumor cells.

Tumor regression and immunity in combination therapy with anti-CEA chimeric antigen receptor T cells and anti-CEA-IL2 immunocytokine

Targeted immunotherapy of solid cancers with chimeric antigen receptor (CAR) T cells and immunocytokines are attractive options in that they both rely on the specificity of tumor-targeted antibodies. Since carcinoembryonic antigen (CEA) expression in both colon and breast cancers is correlated with poor prognosis, it was chosen as a model tumor target in immunocompetent CEA transgenic (CEATg) mice. A second-generation anti-CEA CAR derived from CEA-specific antibody T84.66 was used to treat murine MC38 colon or E0771 breast carcinomas transfected with CEA. Anti-CEA CAR vs. mock transduced T cells exhibited a CEA-specific cytotoxic and IFNγ dose response to both CEA transfected cell lines vs. their CEA-negative controls. Anti-CEA CAR vs. mock transduced T cells delayed the median survival of CEA transfected s.c. MC38 or orthotopic E0771 tumor-bearing CEATg mice by 2 days. With the addition of one-day prior cyclophosphamide (CY) lymphodepletion, anti-CEA CAR T cell treatment delayed the median survival of MC38/CEA and E0771/CEA tumor-bearing CEATg mice by ten and 3 days, respectively. Since CAR T cells require IL2 for survival and expansion, anti-CEA-IL2 immunocytokine (ICK) treatment was performed post CAR T cell therapy. Single ICK treatment 1 day after CY plus anti-CEA CAR T cell therapy in the MC38/CEA model, and two ICK treatments every 3 days after CY plus anti-CEA CAR T cell therapy in the E0771/CEA model were ineffective, while four ICK treatments every 3 days after CY plus anti-CEA CAR T cell therapy completely eradicated MC38/CEA tumor growth and induced tumor immunity when the mice were re-challenged with tumor. These studies show the therapeutic potential of anti-CEA CAR T cells combined with ICK to treat CEA-positive tumors.

Abbreviations: CAR: Chimeric antigen receptor, CEA: Carcinoembryonic antigen, CEACAM5, ICK: Immunocytokine, CY: Cyclophosphamide, CEATg mouse: transgenic CEA mouse, TDLN: Tumor-draining lymph node

Genetic Mechanism of Leukemia Relapse Following CD19 Chimeric Antigen Receptor T Cell Therapy

Chimeric antigen receptor T cell therapy (CART) has achieved excellent results in the past 10 years for the treatment of leukemia. Treatment of B cell acute lymphoblastic leukemia by anti-CD19 CART can reach a complete remission rate of 90%. Although CART has greatly improved the treatment of patients with leukemia and lymphoma, as many as one-third of patients can suffer disease relapse after CART. The tumor surface marker CD19 is negative in most patients who relapse, and these patients display high expression of CD19 before treatment. In this review, the current causes of CD19-negative relapses after CD19 CART against leukemia, and the mechanisms of target escape are briefly summarized. Also, methods and strategies for treating relapse to provide references for the treatment of leukemia relapse are also discussed.

Targeting CD79b for Chimeric Antigen Receptor T-Cell Therapy of B-Cell Lymphomas

BACKGROUND

Although chimeric antigen receptor (CAR) T-cell therapy targeting antigens expressed in refractory and relapsed non-Hodgkin B-cell lymphoma, such as CD19 and CD22, has achieved encouraging clinical effects, some patients fail to attain remission, or relapse after CAR T-cell therapy, which has been ascribed to the loss of the target antigens.

OBJECTIVE

To evaluate CD79b as an alternative target for CAR T-cell B-cell lymphoma therapy.

PATIENT AND METHODS

The expression of CD79b in different B-cell lymphomas was determined. Anti-CD79b CAR T-cells expressing one of two different CARs were generated, and a series of in vitro and in vivo experiments were conducted to assess the CAR T-cell function.

RESULTS

We found that CD79b was extensively expressed on the tumor cells of patients with various types of lymphoma regardless of stage, subtype, and cytogenetic and molecular features. Anti-CD79b CAR T-cells were highly specific and effective for the treatment of B-cell lymphomas.

CONCLUSIONS

Our data indicate that CD79b could be used as a target for CAR T-cell therapy of B-cell lymphomas, and further clinical development is warranted.

Targeted Treatment of Follicular Lymphoma

Follicular lymphoma (FL) is the most common indolent B-cell lymphoma. Advanced stage disease is considered incurable and is characterized by a prolonged relapsing/remitting course. A significant minority have less favorable outcomes, particularly those with transformed or early progressive disease. Recent advances in our understanding of the unique genetic and immune biology of FL have led to increasingly potent and precise novel targeted agents, suggesting that a chemotherapy-future may one day be attainable. The current pipeline of new therapeutics is unprecedented. Particularly exciting is that many agents have non-overlapping modes of action, offering potential new combinatorial options and synergies. This review provides up-to-date clinical and mechanistic data on these new therapeutics. Ongoing dedicated attention to basic, translational and clinical research will provide further clarity as to when and how to best use these agents, to improve efficacy without eliciting unnecessary toxicity.

Challenges and Clinical Strategies of CAR T-Cell Therapy for Acute Lymphoblastic Leukemia: Overview and Developments

Chimeric antigen receptor (CAR) T-cell therapy exhibits desirable and robust efficacy in patients with acute lymphoblastic leukemia (ALL). Stimulated by the revolutionized progress in the use of FDA-approved CD19 CAR T cells, novel agents with CAR designs and targets are being produced in pursuit of superior performance. However, on the path from bench to bedside, new challenges emerge. Accessibility is considered the initial barrier to the transformation of this patient-specific product into a commercially available product. To ensure infusion safety, profound comprehension of adverse events and proactive intervention are required. Additionally, resistance and relapse are the most critical and intractable issues in CAR T-cell therapy for ALL, thus precluding its further development. Understanding the limitations through up-to-date insights and characterizing multiple strategies will be critical to leverage CAR T-cell therapy flexibly for use in clinical situations. Herein, we provide an overview of the application of CAR T-cell therapy in ALL, emphasizing the main challenges and potential clinical strategies in an effort to promote a standardized set of treatment paradigms for ALL.

Current Trends in Cancer Immunotherapy

The search for an effective drug to treat oncological diseases, which have become the main scourge of mankind, has generated a lot of methods for studying this affliction. It has also become a serious challenge for scientists and clinicians who have needed to invent new ways of overcoming the problems encountered during treatments, and have also made important discoveries pertaining to fundamental issues relating to the emergence and development of malignant neoplasms. Understanding the basics of the human immune system interactions with tumor cells has enabled new cancer immunotherapy strategies. The initial successes observed in immunotherapy led to new methods of treating cancer and attracted the attention of the scientific and clinical communities due to the prospects of these methods. Nevertheless, there are still many problems that prevent immunotherapy from calling itself an effective drug in the fight against malignant neoplasms. This review examines the current state of affairs for each immunotherapy method, the effectiveness of the strategies under study, as well as possible ways to overcome the problems that have arisen and increase their therapeutic potentials.

The Cerebroventricular Environment Modifies CAR T Cells for Potent Activity against Both Central Nervous System and Systemic Lymphoma

Lymphomas with central nervous system (CNS) involvement confer a worse prognosis than those without CNS involvement, and patients currently have limited treatment options. T cells genetically engineered with CD19-targeted chimeric antigen receptors (CAR) are effective against B-cell malignancies and show tremendous potential in the treatment of systemic lymphoma. We aimed to leverage this strategy toward a more effective therapy for patients with lymphoma with CNS disease. NOD-scid IL2Rgamma^null (NSG) mice with CNS and/or systemic lymphoma were treated with CD19-CAR T cells via intracerebroventricular (ICV) or intravenous (IV) injection. CAR T cells isolated after treatment were rigorously examined for phenotype, gene expression, and function. We observed that CAR T cells infused ICV, but not IV, completely and durably eradicated both CNS and systemic lymphoma. CAR T cells delivered ICV migrated efficiently to the periphery, homed to systemic tumors, and expanded in vivo, leading to complete elimination of disease and resistance to tumor rechallenge. Mechanistic studies indicated that ICV-delivered CAR T cells are conditioned by exposure to cerebrospinal fluid in the ICV environment for superior antilymphoma activity and memory function compared with IV-delivered CAR T cells. Further analysis suggested that manipulating cellular metabolism or preactivating therapeutic CAR T cells with antigen ex vivo may improve the efficacy of CAR T cells in vivo Our demonstration that ICV-delivered CD19-CAR T cells had activity against CNS and systemic lymphoma could offer a valuable new strategy for treatment of B-cell malignancies with CNS involvement.

How I treat adults with advanced acute lymphoblastic leukemia eligible for CD19-targeted immunotherapy

CD19-targeted immunotherapies have drastically improved outcomes for relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (ALL) patients. Such therapies, including blinatumomab and CD19 chimeric antigen receptor (CD19CAR) T cells, yield high remission rates and can bridge to more definitive consolidation therapy with curative intent. Both treatments are approved by the US Food and Drug Administration (FDA) for r/r ALL (CD19CAR T-cell approval is restricted to patients ≤25 years old). Although availability of blinatumomab and CD19CAR T cells has extended options for the treatment of r/r ALL, prioritizing the sequence of these agents on an individual-patient basis may be difficult for the treating physician. Considering each therapy's advantages, limitations, and challenges is necessary when choosing between them. Although patients may receive both blinatumomab and CD19CAR T cells sequentially in cases that fail to respond or subsequently relapse, a proportion of patients treated with CD19-targeted immunotherapy will lose expression of CD19 and will be excluded from receiving the alternative CD19-targeted therapy. Thus, weighing all considerations for each patient before selecting a CD19-targeted immunotherapy is crucial. Here, we discuss real-life scenarios of adults with r/r ALL, in which we selected either blinatumomab or CD19CAR T-cell therapy, and the rationale behind each decision.

Point mutation in CD19 facilitates immune escape of B cell lymphoma from CAR-T cell therapy

BACKGROUND

Tumor relapse due to mutation in CD19 can hinder the efficacy of chimeric antigen receptor (CAR)-T cell therapy. Herein, we focused on lymphoma patients whose B cells exhibited a point mutation in CD19 of B cells after CAR-T cell infusion.

METHODS

The CAR-T and CD19⁺ B cells from peripheral blood or bone marrow were assessed using flow cytometry. Genome sequencing was conducted to identify the molecular characteristics of CAR-T and CD19⁺ B cells from pre-relapse and postrelapse samples. CD19 in CARs comprising single chain fragments variable (scFV) antibody with FMC63 or 21D4 was constructed. The cytotoxic efficacy of CAR-T cells was also evaluated via in vitro and in vivo experiments.

RESULTS

A patient with high-grade B cell lymphoma exhibited complete response, but the lymphoma relapsed in her left breast at 6 months after CD19 CAR (FMC63)-T cell infusion. A mutation was found in exon 3 of CD19 (p.163. R-L) in malignant B cells of the patient. In two lymphoma patients who exhibited resistance to CAR-T cell therapy, a mutation was detected in exon 3 of CD19 (p.174. L-V). Functional analysis revealed that FMC63 CAR-T cells exhibited antitumor ability against wild-type CD19⁺ cells but were unable to eradicate these two types of mutated CD19⁺ cells. Interestingly, 21D4 CAR-T cells were potentially capable of eradicating these mutated CD19⁺ cells and exhibiting high antitumor capacity against CD19⁺ cells with loss of exon 1, 2, or 3.

CONCLUSIONS

These findings suggest that point mutation can facilitate immune escape from CAR-T cell therapy and that alternative CAR-T cells can effectively eradicate the mutated B cells, providing an individualized therapeutic approach for lymphoma patients showing relapse.

Systemic Lupus Erythematosus (SLE) Therapy: The Old and the New

Despite recent improvements in the treatment of systemic lupus erythematosus (SLE), disease activity, comorbidities and drug toxicity significantly contribute to the risk of progressive irreversible damage accrual and increased mortality in patients with this chronic disease. Moreover, even lupus patients in remission often report residual symptoms, such as fatigue, which have a considerable impact on their health-related quality of life. In recent decades, SLE treatment has moved from the use of hydroxychloroquine, systemic glucocorticosteroids and conventional immunosuppressive drugs to biologic agents, of which belimumab is the first and only biologic agent approved for the treatment for SLE to date. Novel therapies targeting interferons, cytokines and their receptors, intracellular signals, plasma cells, T lymphocytes and co-stimulatory molecules are being evaluated. In the context of a holistic approach, growing evidence is emerging of the importance of correct lifestyle habits in the management of lupus manifestations and comorbidities. The aim of this paper is to provide an overview of current pharmacological and non-pharmacological treatment options and emerging therapies in SLE.