CD22 CAR T-cell therapy in refractory or relapsed B acute lymphoblastic leukemia

Comprehensive analysis of the efficacy and safety of CAR T-cell therapy in patients with relapsed or refractory B-cell acute lymphoblastic leukaemia: a systematic review and meta-analysis

BACKGROUND

Relapse/refractory B-cell acute lymphoblastic leukaemia (r/r B-ALL) represents paediatric cancer with a challenging prognosis. CAR T-cell treatment, considered an advanced treatment, remains controversial due to high relapse rates and adverse events. This study assessed the efficacy and safety of CAR T-cell therapy for r/r B-ALL.

METHODS

The literature search was performed on four databases. Efficacy parameters included minimal residual disease negative complete remission (MRD-CR) and relapse rate (RR). Safety parameters constituted cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS).

RESULTS

Anti-CD22 showed superior efficacy with the highest MRD-CR event rate and lowest RR, compared to anti-CD19. Combining CAR T-cell therapy with haploidentical stem cell transplantation improved RR. Safety-wise, bispecific anti-CD19/22 had the lowest CRS rate, and anti-CD22 showed the fewest ICANS. Analysis of the costimulatory receptors showed that adding CD28ζ to anti-CD19 CAR T-cell demonstrated superior efficacy in reducing relapses with favorable safety profiles.

CONCLUSION

Choosing a more efficacious and safer CAR T-cell treatment is crucial for improving overall survival in acute leukaemia. Beyond the promising anti-CD22 CAR T-cell, exploring costimulatory domains and new CD targets could enhance treatment effectiveness for r/r B-ALL.

Chimeric antigen receptor-induced antigen loss protects CD5.CART cells from fratricide without compromising on-target cytotoxicity

Chimeric antigen receptor T cells (CART) targeting lymphocyte antigens can induce T cell fratricide and require additional engineering to mitigate self-damage. We demonstrate that the expression of a chimeric antigen receptor (CAR) targeting CD5, a prominent pan-T cell antigen, induces rapid internalization and complete loss of the CD5 protein on T cells, protecting them from self-targeting. Notably, exposure of healthy and malignant T cells to CD5.CART cells induces similar internalization of CD5 on target cells, transiently shielding them from cytotoxicity. However, this protection is short-lived, as sustained activity of CD5.CART cells in patients with T cell malignancies results in full ablation of CD5+ T cells while sparing healthy T cells naturally lacking CD5. These results indicate that continuous downmodulation of the target antigen in CD5.CART cells produces effective fratricide resistance without undermining their on-target cytotoxicity.

Advances in the treatment of adults with newly diagnosed B-cell acute lymphoblastic leukemia: the role of frontline immunotherapy-based regimens

Blinatumomab and inotuzumab ozogamicin (INO) are both active in relapsed/refractory B-cell acute lymphoblastic leukemia (ALL) and improve outcomes compared with conventional chemotherapy in this setting. Several prospective clinical trials have explored the use of these agents in adults with newly diagnosed B-cell ALL, with promising outcomes observed in younger and older adults and in both Philadelphia chromosome (Ph)-positive and Ph-negative ALL. These novel regimens result in high rates of deep measurable residual disease (MRD) negativity and may improve survival compared with chemotherapy-only approaches, allowing for less reliance on intensive chemotherapy and allogeneic hematopoietic stem cell transplantation (HSCT). This review discusses novel approaches to integrating INO and/or blinatumomab into frontline ALL regimens, including the potential role of chemotherapy-free regimens in some subgroups. The role of MRD monitoring is also discussed, including how this can inform decisions for consolidative allogeneic HSCT or investigational approaches with CD19 CAR T-cells.

Efficacy and risk of donor-derived CAR-T treatment of relapsed B-cell acute lymphoblastic leukemia after hematopoietic stem cell transplantation

The one-year survival rate for patients experiencing a relapse of B-cell acute lymphocytic leukemia (B-ALL) following hematopoietic stem cell transplantation (HSCT) is approximately 30%. Patients experiencing a relapse after allogeneic HSCT frequently encounter difficulties in obtaining autologous CAR-T products. We conducted a study involving 14 patients who received donor-derived CAR-T therapy for relapsed B-ALL following HSCT between August 2019 and May 2023 in our center. The results revealed a CR/CRi rate of 78.6% (11/14), a GVHD rate of 21.4% (3/14), and a 1-year overall survival (OS) rate of 56%. Decreased bone marrow donor cell chimerism in 9 patients recovered after CAR-T therapy. The main causes of death were disease progression and infection. Further analysis showed that GVHD (HR 7.224, 95% CI 1.42-36.82, P = 0.017) and platelet recovery at 30 days (HR 6.807, 95% CI 1.61-28.83, P = 0.009) are significantly associated with OS after CAR-T therapy. Based on the findings, we conclude that donor-derived CAR-T cells are effective in treating relapsed B-ALL patients following HSCT. Additionally, GVHD and poor platelet recovery impact OS, but further verification with a larger sample size is needed.

The role of chimeric antigen receptor T cells targeting more than one antigen in the treatment of B-cell malignancies

Several products containing chimeric antigen receptor T cells targeting CD19 (CART19) have been approved for the treatment of patients with relapsed/refractory non-Hodgkin's lymphoma (NHL) and acute lymphoblastic leukaemia (ALL). Despite very impressive response rates, a significant percentage of patients experience disease relapse and die of progressive disease. A major cause of CART19 failure is loss or downregulation of CD19 expression in tumour cells, which has prompted a myriad of novel strategies aimed at targeting more than one antigen (e.g. CD19 and CD20 or CD22). Dual targeting can the accomplished through co-administration of two separate products, co-transduction with two different vectors, bicistronic cassettes or tandem receptors. In this manuscript, we review the pros and cons of each strategy and the clinical results obtained so far.

Targeting Siglec-Sialylated MUC1 Immune Axis in Cancer

Siglecs play a key role in mediating cell-cell interactions via the recognition of different sialylated glycoconjugates, including tumor-associated MUC1, which can lead to the activation or inhibition of the immune response. The activation occurs through the signaling of Siglecs with the cytoplasmic immunoreceptor tyrosine-based activation motif (ITAM)-containing proteins, while the inhibition signal is a result of the interaction of intracellular immunoreceptor tyrosine-based inhibition motif (ITIM)-bearing receptors. The interaction of tumor-associated MUC1 sialylated glycans with Siglecs via ITIM motifs decreases antitumor immunity. Consequently, these interactions are expected to play a key role in tumor evasion. Efforts to modulate the response of immune cells by blocking the immune-suppressive effects of inhibitory Siglecs, driving immune-activating Siglecs, and/or altering the synthesis and expression of the sialic acid glycocalyx are new therapeutic strategies deserving further investigation. We will highlight the role of Siglec's family receptors in immune evasion through interactions with glycan ligands in their natural context, presented on the protein such as MUC1, factors affecting their fine binding specificities, such as the role of multivalency either at the ligand or receptor side, their spatial organization, and finally the current and future therapeutic interventions targeting the Siglec-sialylated MUC1 immune axis in cancer.

Discovery and preclinical development of a therapeutically active nanobody-based chimeric antigen receptor targeting human CD22

Chimeric antigen receptor (CAR) T cell therapies targeting B cell-restricted antigens CD19, CD20, or CD22 can produce potent clinical responses for some B cell malignancies, but relapse remains common. Camelid single-domain antibodies (sdAbs or nanobodies) are smaller, simpler, and easier to recombine than single-chain variable fragments (scFvs) used in most CARs, but fewer sdAb-CARs have been reported. Thus, we sought to identify a therapeutically active sdAb-CAR targeting human CD22. Immunization of an adult Llama glama with CD22 protein, sdAb-cDNA library construction, and phage panning yielded >20 sdAbs with diverse epitope and binding properties. Expressing CD22-sdAb-CAR in Jurkat cells drove varying CD22-specific reactivity not correlated with antibody affinity. Changing CD28- to CD8-transmembrane design increased CAR persistence and expression in vitro. CD22-sdAb-CAR candidates showed similar CD22-dependent CAR-T expansion in vitro, although only membrane-proximal epitope targeting CD22-sdAb-CARs activated direct cytolytic killing and extended survival in a lymphoma xenograft model. Based on enhanced survival in blinded xenograft studies, a lead CD22sdCAR-T was selected, achieving comparable complete responses to a benchmark short linker m971-scFv CAR-T in high-dose experiments. Finally, immunohistochemistry and flow cytometry confirm tissue and cellular-level specificity of the lead CD22-sdAb. This presents a complete report on preclinical development of a novel CD22sdCAR therapeutic.

Optimizing CAR-T cell therapy in adults with B-cell acute lymphoblastic leukemia

Chimeric antigen receptor T-cell (CAR-T) therapy has demonstrated unprecedented success in the treatment of various hematologic malignancies including relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). Currently, there are two FDA-approved CD19-directed CAR-T cell products for the treatment of adults with R/R B-ALL. Despite high remission rates following CD19 CAR-T cell therapy in R/R B-ALL, remission durability remains limited in most adult patients, with relapse observed frequently in the absence of additional consolidation therapy. Furthermore, the burden of CAR-T cell toxicity remains significant in adults with R/R B-ALL and further limits the wide utilization of this effective therapy. In this review, we discuss patient and disease factors that are linked to CAR-T cell therapy outcomes in R/R B-ALL and strategies to optimize durability of response to reduce relapse and mitigate toxicity in the adult population. We additionally discuss future approaches being explored to maximize the benefit of CAR-T in adults with B-ALL.

The Potential of Siglecs and Sialic Acids as Biomarkers and Therapeutic Targets in Tumor Immunotherapy

The dysregulation of sialic acid is closely associated with oncogenesis and tumor progression. Most tumor cells exhibit sialic acid upregulation. Sialic acid-binding immunoglobulin-like lectins (Siglecs) are receptors that recognize sialic acid and are expressed in various immune cells. The activity of Siglecs in the tumor microenvironment promotes immune escape, mirroring the mechanisms of the well-characterized PD-1/PD-L1 pathway in cancer. Cancer cells utilize sialic acid-linked glycans to evade immune surveillance. As Siglecs exhibit similar mechanisms as the established immune checkpoint inhibitors (ICIs), they are potential therapeutic targets for different forms of cancer, especially ICI-resistant malignancies. Additionally, the upregulation of sialic acid serves as a potential tumor biomarker. This review examines the feasibility of using sialic acid and Siglecs for early malignant tumor detection and discusses the potential of targeting Siglec-sialic acid interaction as a novel cancer therapeutic strategy.

Myeloid leukemia-derived galectin-1 downregulates CAR expression to hinder cytotoxicity of CAR T cells

BACKGROUND

Chimeric antigen receptor (CAR) T cells have shown significant activity in B-lineage malignancies. However, their efficacy in myeloid leukemia has not been successful due to unclear molecular mechanisms.

METHODS

We conducted in vitro and in vivo experiments to investigate whether myeloid leukemia cells directly induce CAR down-regulation. Furthermore, we designed a CD33 CARKR in which all lysines in the cytoplasmic domain of CAR were mutated to arginine and verified through in vitro experiments that it could reduce the down-regulation of surface CARs and enhance the killing ability. Transcriptome sequencing was performed on various AML and ALL cell lines and primary samples, and the galectin-1-specific inhibitory peptide (anginex) successfully rescued the killing defect and T-cell activation in in vitro assays.

RESULTS

CAR down-regulation induced by myeloid leukemia cells under conditions of low effector-to-tumor ratio, which in turn impairs the cytotoxicity of CAR T cells. In contrast, lysosomal degradation or actin polymerization inhibitors can effectively alleviate CAR down-regulation and restore CAR T cell-mediated anti-tumor functions. In addition, this study identified galectin-1 as a critical factor used by myeloid leukemia cells to induce CAR down-regulation, resulting in impaired T-cell activation.

CONCLUSION

The discovery of the role of galectin-1 in cell surface CAR down-regulation provides important insights for developing strategies to restore anti-tumor functions.

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.

CAR-T Cell Therapy in B-Cell Acute Lymphoblastic Leukemia

Treatment of refractory and relapsed (R/R) B acute lymphoblastic leukemia (B-ALL) is an unmet medical need in both children and adults. Studies carried out in the last two decades have shown that autologous T cells engineered to express a chimeric antigen receptor (CAR-T) represent an effective technique for treating these patients. Antigens expressed on B-cells, such as CD19, CD20, and CD22, represent targets suitable for treating patients with R/R B-ALL. CD19 CAR-T cells induce a high rate (80-90%) of complete remissions in both pediatric and adult R/R B-ALL patients. However, despite this impressive rate of responses, about half of responding patients relapse within 1-2 years after CAR-T cell therapy. Allo-HSCT after CAR-T cell therapy might consolidate the therapeutic efficacy of CAR-T and increase long-term outcomes; however, not all the studies that have adopted allo-HSCT as a consolidative treatment strategy have shown a benefit deriving from transplantation. For B-ALL patients who relapse early after allo-HSCT or those with insufficient T-cell numbers for an autologous approach, using T cells from the original stem cell donor offers the opportunity for the successful generation of CAR-T cells and for an effective therapeutic approach. Finally, recent studies have introduced allogeneic CAR-T cells generated from healthy donors or unmatched, which are opportunely manipulated with gene editing to reduce the risk of immunological incompatibility, with promising therapeutic effects.

Exploratory study on the efficacy of bortezomib combining mitoxantrone or CD22-CAR T therapy targeting CD19-negative relapse after CD19-CAR T cell therapy with a simpler cell-line-based model

Target-negative relapse after CD19 chimeric antigen receptor engineered (CAR) T cell therapy for patients with B lineage acute lymphoblastic leukemia (B-ALL) presents limited treatment options with dismal outcomes. Although CD22-CAR T cells mediate similarly potent antineoplastic effects in patients with CD19dim or even CD19-negative relapse following CD19-directed immunotherapy, a high rate of relapse associated with diminished CD22 cell surface expression has also been observed. Therefore, it is unclear whether any other therapeutic options are available. Mitoxantrone has shown significant antineoplastic activity in patients with relapsed or refractory leukemia over the past decades, and in some cases, the addition of bortezomib to conventional chemotherapeutic agents has demonstrated improved response rates. However, whether this mitoxantrone and bortezomib combination therapy is effective for those patients who have relapsed B-ALL after receiving CD19-CAR T cell therapy remains to be elucidated. In this study, we established a cellular model system using a CD19-positive B-ALL cell line Nalm-6 to investigate the treatment options for CD19-negative relapsed B-ALL after CD19-CAR T cell therapy. In addition to CD22-CAR T therapy, we observed that the combination of bortezomib and mitoxantrone exhibited effective anti-leukemia activity in the CD19-negative Nalm-6 cell line by downregulating p-AKT and p-mTOR. These results suggest that this combination therapy is a possible option for target-negative refractory leukemia cells after CAR-T cell treatment.

CAR-T cell therapy for hematological malignancies: History, status and promise

For many years, the methods of cancer treatment are usually surgery, chemotherapy and radiation therapy. Although these methods help to improve the condition, most tumors still have a poor prognosis. In recent years, immunotherapy has great potential in tumor treatment. Chimeric antigen receptor T-cell immunotherapy (CAR-T) uses the patient's own T cells to express chimeric antigen receptors. Chimeric antigen receptor (CAR) recognizes tumor-associated antigens and kills tumor cells. CAR-T has achieved good results in the treatment of hematological tumors. In 2017, the FDA approved the first CAR-T for the treatment of B-cell acute lymphoblastic leukemia (ALL). In October of the same year, the FDA approved CAR-T to treat B-cell lymphoma. In order to improve and enhance the therapeutic effect, CAR-T has become a research focus in recent years. The structure of CAR, the targets of CAR-T treatment, adverse reactions and improvement measures during the treatment process are summarized. This review is an attempt to highlight recent and possibly forgotten findings of advances in chimeric antigen receptor T cell for treatment of hematological tumors.

Sequential CD19 and CD22 chimeric antigen receptor T-cell therapy for childhood refractory or relapsed B-cell acute lymphocytic leukaemia: a single-arm, phase 2 study

BACKGROUND

Relapses frequently occur following CD19-directed chimeric antigen receptor (CAR) T-cell treatment for relapsed or refractory B-cell acute lymphocytic leukaemia in children. We aimed to assess the activity and safety of sequential CD19-directed and CD22-directed CAR T-cell treatments.

METHODS

This single-centre, single-arm, phase 2 trial, done at Beijing GoBroad Boren Hospital, Beijing, China, included patients aged 1-18 years who had relapsed or refractory B-cell acute lymphocytic leukaemia with CD19 and CD22 positivity greater than 95% and an Eastern Cooperative Oncology Group performance status of 0-2. Patients were initially infused with CD19-directed CAR T cells intravenously, followed by CD22-directed CAR T-cell infusion after minimal residual disease-negative complete remission (or complete remission with incomplete haematological recovery) was reached and all adverse events (except haematological adverse events) were grade 2 or better. The target dose for each infusion was 0·5 × 106 to 5·0 × 106 cells per kg. The primary endpoint was objective response rate at 3 months after the first infusion. Secondary endpoints were duration of remission, event-free survival, disease-free survival, overall survival, safety, pharmacokinetics, and B-cell quantification. The prespecified activity analysis included patients who received the target dose and the safety analysis included all treated patients. This study is registered with ClinicalTrials.gov, NCT04340154, and enrolment has ended.

FINDINGS

Between May 28, 2020, and Aug 16, 2022, 81 participants were enrolled, of whom 31 (38%) were female and 50 (62%) were male. Median age was 8 years (IQR 6-10), all patients were Asian. All 81 patients received the first infusion and 79 (98%) patients received sequential infusions, CD19-directed CAR T cells at a median dose of 2·7 × 106 per kg (IQR 1·1 × 106 to 3·7 × 106) and CD22-directed CAR T cells at a median dose of 2·2 × 106 per kg (1·1 × 106 to 3·7 × 106), with a median interval of 39 days (37-41) between the two infusions. 62 (77%) patients received the target dose, including two patients who did not receive CD22 CAR T cells. At 3 months, 60 (97%, 95% CI 89-100) of the 62 patients who received the target dose had an objective response. Median follow-up was 17·7 months (IQR 11·4-20·9). 18-month event-free survival for patients who received the target dose was 79% (95% CI 66-91), duration of remission was 80% (68-92), and disease-free survival was 80% (68-92) with transplantation censoring; overall survival was 96% (91-100). Common adverse events of grade 3 or 4 between CD19-directed CAR T-cell infusion and 30 days after CD22-directed CAR T-cell infusion included cytopenias (64 [79%] of 81 patients), cytokine release syndrome (15 [19%]), neurotoxicity (four [5%]), and infections (five [6%]). Non-haematological adverse events of grade 3 or worse more than 30 days after CD22-directed CAR T-cell infusion occurred in six (8%) of 79 patients. No treatment-related deaths occurred. CAR T-cell expansion was observed in all patients, with a median peak at 9 days (IQR 7-14) after CD19-directed and 12 days (10-15) after CD22-directed CAR T-cell infusion. At data cutoff, 35 (45%) of 77 evaluable patients had CAR transgenes and 59 (77%) had B-cell aplasia.

INTERPRETATION

This sequential strategy induced deep and sustained responses with an acceptable toxicity profile, and thus potentially provides long-term benefits for children with this condition.

FUNDING

The National Key Research & Development Program of China, the CAMS Innovation Fund for Medical Sciences (CIFMS), and the Non-Profit Central Research Institute Fund of Chinese Academy of Medical Sciences.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

CAR T-Cells for the Treatment of B-Cell Acute Lymphoblastic Leukemia

B-cell acute lymphoblastic leukemia (B-ALL) is the most common subtype of acute leukemia in the pediatric population. The prognosis and treatment of B-ALL have dramatically improved over the past decade with the adoption of intensive and prolonged combination chemotherapy regimens. The advent of novel immunologic agents such as blinatumomab and inotuzumab has changed the treatment landscape of B-ALL. However, patients have continued to relapse, raising the need for novel therapies. Chimeric antigen receptor (CAR) T-cells have achieved a milestone in the treatment of B-ALL. Two CD19-targeting CAR T-cells were approved by the Food and Drug Administration and the European Medicines Agency for the treatment of relapsed and/or refractory B-ALL. In this review, we review the available data regarding CD19-targeting CAR T-cells with their safety profile as well as the mechanism of resistance to these agents and the way to overcome this resistance.

Complete spectrum of adverse events associated with chimeric antigen receptor (CAR)-T cell therapies

Chimeric antigen receptor (CAR)-T cell therapies have been approved by FDA to treat relapsed or refractory hematological malignancies. However, the adverse effects of CAR-T cell therapies are complex and can be challenging to diagnose and treat. In this review, we summarize the major adverse events, including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and CAR T-cell associated HLH (carHLH), and discuss their pathophysiology, symptoms, grading, and diagnosis systems, as well as management. In a future outlook, we also provide an overview of measures and modifications to CAR-T cells that are currently being explored to limit toxicity.

Targeting CD22 for B-cell hematologic malignancies

CD19-targeted chimeric receptor antigen (CAR)-T cell therapy has shown remarkable clinical efficacy in the treatment of relapsed or refractory (R/R) B-cell malignancies. However, 30%-60% of patients eventually relapsed, with the CD19-negative relapse being an important hurdle to sustained remission. CD22 expression is independent of CD19 expression in malignant B cells. Consequently, CD22 is a potential alternative target for CD19 CAR-T cell-resistant patients. CD22-targeted therapies, mainly including the antibody-drug conjugates (ADCs) and CAR-T cells, have come into wide clinical use with acceptable toxicities and promising efficacy. In this review, we explore the molecular and physiological characteristics of CD22, development of CD22 ADCs and CAR-T cells, and the available clinical data on CD22 ADCs and CAR-T cell therapies. Furthermore, we propose some perspectives for overcoming tumor escape and enhancing the efficacy of CD22-targeted therapies.

CD22 is a potential target of CAR-NK cell therapy for esophageal squamous cell carcinoma

BACKGROUND

Chimeric antigen receptor NK (CAR-NK) cell therapy is one of the most promising immunotherapies. Although it has shown a significant therapeutic effect in hematologic malignancies, few successes have been obtained in solid tumors including esophageal squamous cell carcinoma (ESCC). The major reasons are lack of specific cell surface antigens and complex tumor microenvironment. Here we identify CD22, a well-known tumor surface marker in hematologic malignancies, is expressed in ESCC, possibly serving as a potential target of CAR-NK cell therapy.

METHODS

The expression of 13 tumor cell surface antigens used clinically was analyzed in patients from The Cancer Genome Atlas (TCGA) database. Also, mRNA expression were detected in 2 ESCC cell lines and 2 patients samples by qCPR. Then according to Venn diagram, CD22 was selected for further investigation. Following this, the expression of CD22 by immunofluorescence (IF) in ESCC cell lines and by immunohistochemistry (IHC) in 87 cases of human ESCC samples was detected respectively. On the basis of H-score results, the correlation between CD22 expression and clinical parameters was analyzed. As a proof, the efficacy of CD22-targeted CAR-NK cells against ESCC cell lines was performed by a real-time cell analyzer (RTCA) platform.

RESULTS

KYSE-140 and KYSE-150 cell lines displayed surface expression of CD22. IHC showed an 80.46% (70/87) positive rate in ESCC patient samples. Among these, cell membranous expression of CD22 was observed in 27.59% (24/87) patient samples. Through chi-square test, expression of CD22 in ESCC was associated with lymph node metastasis while it was no related to the depth of tumor invasion and clinical stage. Engineered CD22-targeted CAR-NK cells exhibited inhibitory growth capability against ESCC cell lines (p < 0.0001).

CONCLUSIONS

CD22 is a potential tumor surface antigen capable of being targeted by CAR-NK cells in ESCC. And potential therapeutics for ESCC may be developed based on immune cells expressing anti-CD22 CAR. The study also indicates that CD22 CAR-NK cells could be used in other cancers and more in vivo experiments are needed.

CAR T-Cells in Acute Lymphoblastic Leukemia: Current Status and Future Prospects

The currently available treatment for acute lymphoblastic leukemia (ALL) is mainly dependent on the combination of chemotherapy, steroids, and allogeneic stem cell transplantation. However, refractoriness and relapse (R/R) after initial complete remission may reach up to 20% in pediatrics. This percentage may even reach 60% in adults. To overcome R/R, a new therapeutic approach was developed using what is called chimeric antigen receptor-modified (CAR) T-cell therapy. The Food and Drug Administration (FDA) in the United States has so far approved four CAR T-cells for the treatment of ALL. Using this new therapeutic strategy has shown a remarkable success in treating R/R ALL. However, the use of CAR T-cells is expensive, has many imitations, and is associated with some adverse effects. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are two common examples of these adverse effects. Moreover, R/R to CAR T-cell therapy can take place during treatment. Continuous development of this therapeutic strategy is ongoing to overcome these limitations and adverse effects. The present article overviews the use of CAR T-cell in the treatment of ALL, summarizing the results of relevant clinical trials and discussing future prospects intended to improve the efficacy of this therapeutic strategy and overcome its limitations.

Updated Indications for Immune Effector Cell Therapy: 2023 Guidelines from the American Society for Transplantation and Cellular Therapy

The American Society for Transplantation and Cellular Therapy (ASTCT) published its guidelines on indications for autologous and allogeneic hematopoietic cell transplantation (HCT) and immune effector cell therapy (IECT) in 2020. Since then, we have witnessed rapid advancements in the field of IECT, resulting in several new chimeric antigen receptor T cell (CAR-T) products and disease indications being approved by the US Food and Drug Administration (FDA). To keep abreast of these practice changes, the ASTCT Committee on Practice Guidelines commissioned a focused update covering CAR-T therapy indications. Here we present updated ASTCT recommendations on indications for CAR-T therapy. Only FDA-approved indications for CAR-T were recommended and categorized as "standard of care," where the indication is well defined and supported by evidence. The ASTCT will continue to periodically review these guidelines and update them as new evidence becomes available.

Targeted cellular therapy for treatment of relapsed or refractory leukemia

While the mainstay of treatment for high-risk or relapsed, refractory leukemia has historically revolved around allogeneic hematopoietic stem cell transplant (allo-HSCT), targeted immunotherapies have emerged as a promising therapeutic option, especially given the poor prognosis of patients who relapse after allo-HSCT. Novel cellular immunotherapies that harness the cytotoxic abilities of the immune system in a targeted manner (often called "adoptive" cell therapy), have changed the way we treat r/r hematologic malignancies and continue to change the treatment landscape given the rapid evolution of these powerful, yet sophisticated precision therapies that often offer a less toxic alternative to conventional salvage therapies. Importantly, adoptive cell therapy can be allo-HSCT-enabling or a therapeutic option for patients in whom transplantation has failed or is contraindicated. A solid understanding of the core concepts of adoptive cell therapy is necessary for stem cell transplant physicians, nurses and ancillary staff given its proximity to the transplant field as well as its inherent complexities that require specific expertise in compliant manufacturing, clinical application, and risk mitigation. Here we will review use of targeted cellular therapy for the treatment of r/r leukemia, focusing on chimeric antigen receptor T-cells (CAR T-cells) given the remarkable sustained clinical responses leading to commercial approval for several hematologic indications including leukemia, with brief discussion of other promising investigational cellular immunotherapies and special considerations for sustainability and scalability.

Effectiveness and safety of CD22 and CD19 dual-targeting chimeric antigen receptor T-cell therapy in patients with relapsed or refractory B-cell malignancies: A meta-analysis

BACKGROUND

The efficacy of CD22 or CD19 chimeric antigen receptor T (CAR-T) cells in the management of acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL) was observed. Because antigen loss and lack of CAR-T-cell persistence are the leading causes of progressive disease following single-antigen targeting, we evaluated CD22/CD19 dual-targeting CAR-T-cell therapy efficacy and safety in relapsed/refractory B-cell malignancies.

METHODS

The Web of Science, PubMed, Cochrane, and Embase databases were searched until July 2022. Patients confirmed with any relapsed/refractory B-cell hematological malignancies were included regardless of age, gender, or ethnicity, receiving CD22 and CD19-dual-targeting CAR-T-cell therapy. The studies conducted on patients with coexisting other cancer were excluded. We used random-effect models to explore the outcome, and heterogeneity was investigated by subgroup analysis.

RESULTS

Fourteen studies (405 patients) were included. The pooled overall response (OR) and complete remission (CR) were 97% and 93%, respectively, for ALL patients. The 1-year proportions of overall survival (OS) and progression-free survival (PFS) were 70% and 49%, respectively. For NHL, OR occurred in 85% of patients, and 57% experienced CR. The results illustrated that the 1-year OS and 1-year PFS were 77% and 65%, respectively. The subgroup analysis showed that the dual-targeting modality achieved higher CR in the following cases: coadministration of CD22/CD19-CAR-T cells and third-generation CAR-T cells combined with ASCT and BEAM pretreatment. The ALL and NHL groups seemed similar in treatment-related toxicity: all grade cytokine release syndrome (CRS), severe CRS, and neurotoxicity occurred in 86%, 7%, and 12% of patients, respectively.

CONCLUSIONS

Our meta-analysis demonstrated that the CD22/CD19 dual-targeting CAR-T-cell strategy has high efficiency with tolerable adverse effects in B-cell malignancies.

A Novel bispecific T-cell engager (BiTE) targeting CD22 and CD3 has both in vitro and in vivo activity and synergizes with blinatumomab in an acute lymphoblastic leukemia (ALL) tumor model

Immunotherapy has revolutionized cancer therapy. Two recently FDA-approved immunotherapies for B-cell malignancies target CD19, in the form of a Bispecific T-Cell Engager (BiTE) antibody construct or chimeric antigen receptor T (CAR-T) cells. Blinatumomab, an FDA-approved BiTE, binds to CD19 on B cells and to CD3 on T cells, mediating effector-target cell contact and T-cell activation that results in effective elimination of target B cells. Although CD19 is expressed by essentially all B-cell malignancies at clinical presentation, relapses with loss or reduction in CD19 surface expression are increasingly recognized as a cause of treatment failure. Therefore, there is a clear need to develop therapeutics for alternate targets. We have developed a novel BiTE consisting of humanized anti-CD22 and anti-CD3 single chain variable fragments. Target binding of the anti-CD22 and anti-CD3 moieties was confirmed by flow cytometry. CD22-BiTE promoted in vitro cell-mediated cytotoxicity in a dose and effector: target (E:T)-dependent fashion. Additionally, in an established acute lymphoblastic leukemia (ALL) xenograft mouse model, CD22-BiTE demonstrated tumor growth inhibition, comparable to blinatumomab. Further, the combination of blinatumomab and CD22-BiTE yielded increased efficacy in vivo when compared to the single agents. In conclusion, we report here the development of a new BiTE with cytotoxic activity against CD22+ cells which could represent an alternate or complementary therapeutic option for B-cell malignancies.

The onco-embryonic antigen ROR1 is a target of chimeric antigen T cells for colorectal cancer

Colorectal cancer is globally ranked second in both incidence and mortality rate. It usually develops during the middle or late stages of diagnosis, and is characterized by easy metastasis, poor prognosis, and a significant decline in postoperative quality of life. ROR1 is an excellent oncoembryonic antigen in numerous immunotherapy treatments for tumors. Additionally, it is overexpressed in colorectal cancer. To fill the void in CRC treatment with ROR1 as a target of CAR-T immunotherapy, we designed and prepared antiROR1-CART. This third-generation CAR-T cell can effectively inhibit the growth of colorectal cancer in vitro and in vivo.

Chimeric antigen receptor T-cell therapy for adult B-cell acute lymphoblastic leukemia: state-of-the-(C)ART and the road ahead

Autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has recently been added to the armamentarium in the battle against B-cell acute lymphoblastic leukemia (B-ALL). In this review, we discuss the trials that led to US Food and Drug Administration approval of CAR T-cell therapies in patients with B-ALL. We evaluate the evolving role of allogeneic hematopoietic stem cell transplant in the CAR T-cell era and discuss lessons learned from the first steps with CAR T-cell therapy in ALL. Upcoming innovations in CAR technology, including combined and alternative targets and off-the-shelf allogeneic CAR T-cell strategies are presented. Finally, we envision the role that CAR T cells could take in the management of adult patients with B-ALL in the near future.

Acute Lymphoblastic Leukemia Immunotherapy Treatment: Now, Next, and Beyond

Acute lymphoblastic leukemia (ALL) is a blood cancer that primarily affects children but also adults. It is due to the malignant proliferation of lymphoid precursor cells that invade the bone marrow and can spread to extramedullary sites. ALL is divided into B cell (85%) and T cell lineages (10 to 15%); rare cases are associated with the natural killer (NK) cell lineage (<1%). To date, the survival rate in children with ALL is excellent while in adults continues to be poor. Despite the therapeutic progress, there are subsets of patients that still have high relapse rates after chemotherapy or hematopoietic stem cell transplantation (HSCT) and an unsatisfactory cure rate. Hence, the identification of more effective and safer therapy choices represents a primary issue. In this review, we will discuss novel therapeutic options including bispecific antibodies, antibody-drug conjugates, chimeric antigen receptor (CAR)-based therapies, and other promising treatments for both pediatric and adult patients.

Efficient chimeric antigen receptor (CAR) targeting of a central epitope of CD22

Chimeric antigen receptor (CAR) T cell therapy has had considerable success in the treatment of B cell malignancies. Targeting the B-lineage markerCD19 has brought great advances to treatment of acute lymphoblastic leukemia (ALL) and B cell lymphomas. However, relapse remains an issue in many cases. Such relapse can result from downregulation or loss of CD19 from the malignant cell population, or expression of alternate isoforms. Consequently, there remains a need to target alternative B-cell antigens and diversify the spectrum of epitopes targeted within the same antigen. CD22 has been identified as a substitute target in cases of CD19-negative relapse. One anti-CD22 antibody - clone m971 - targets a membrane-proximal epitope of CD22 and has been widely validated and used in the clinic. Here we have compared m971-CAR with a novel CAR derived from IS7, an antibody that targets a central epitope on CD22. The IS7-CAR has superior avidity, and is active and specific against CD22 positive targets, including B-ALL patient-derived xenograft (PDX) samples. Side-by-side comparisons indicated that while IS7-CAR killed less rapidly than m971-CAR in vitro, it remains efficient in controlling lymphoma xenograft models in vivo. Thus, IS7-CAR presents a potential alternative candidate for treatment of refractory B-cell malignancies.

CD22 CAR T-cell associated hematologic toxicities, endothelial activation and relationship to neurotoxicity

BACKGROUND

Hematologic toxicities, including coagulopathy, endothelial activation, and cytopenias, with CD19-targeted chimeric antigen receptor (CAR) T-cell therapies correlate with cytokine release syndrome (CRS) and neurotoxicity severity, but little is known about the extended toxicity profiles of CAR T-cells targeting alternative antigens. This report characterizes hematologic toxicities seen following CD22 CAR T-cells and their relationship to CRS and neurotoxicity.

METHODS

We retrospectively characterized hematologic toxicities associated with CRS seen on a phase 1 study of anti-CD22 CAR T-cells for children and young adults with relapsed/refractory CD22+ hematologic malignancies. Additional analyses included correlation of hematologic toxicities with neurotoxicity and exploring effects of hemophagocytic lymphohistiocytosis-like toxicities (HLH) on bone marrow recovery and cytopenias. Coagulopathy was defined as evidence of bleeding or abnormal coagulation parameters. Hematologic toxicities were graded by Common Terminology Criteria for Adverse Events V.4.0.

RESULTS

Across 53 patients receiving CD22 CAR T-cells who experienced CRS, 43 (81.1%) patients achieved complete remission. Eighteen (34.0%) patients experienced coagulopathy, of whom 16 had clinical manifestations of mild bleeding (typically mucosal bleeding) which generally subsided following CRS resolution. Three had manifestations of thrombotic microangiopathy. Patients with coagulopathy had higher peak ferritin, D-dimer, prothrombin time, international normalized ratio (INR), lactate dehydrogenase (LDH), tissue factor, prothrombin fragment F1+2 and soluble vascular cell adhesion molecule-1 (s-VCAM-1). Despite a relatively higher incidence of HLH-like toxicities and endothelial activation, overall neurotoxicity was generally less severe than reported with CD19 CAR T-cells, prompting additional analysis to explore CD22 expression in the central nervous system (CNS). Single-cell analysis revealed that in contrast to CD19 expression, CD22 is not on oligodendrocyte precursor cells or on neurovascular cells but is seen on mature oligodendrocytes. Lastly, among those attaining CR, grade 3-4 neutropenia and thrombocytopenia were seen in 65% of patients at D28.

CONCLUSION

With rising incidence of CD19 negative relapse, CD22 CAR T-cells are increasingly important for the treatment of B-cell malignancies. In characterizing hematologic toxicities on CD22 CAR T-cells, we demonstrate that despite endothelial activation, coagulopathy, and cytopenias, neurotoxicity was relatively mild and that CD22 and CD19 expression in the CNS differed, providing one potential hypothesis for divergent neurotoxicity profiles. Systematic characterization of on-target off-tumor toxicities of novel CAR T-cell constructs will be vital as new antigens are targeted.

TRIAL REGISTRATION NUMBER

NCT02315612.

Diagnostic Flow Cytometry in the Era of Targeted Therapies: Lessons from Therapeutic Monoclonal Antibodies and Chimeric Antigen Receptor T-cell Adoptive Immunotherapy

Therapeutic monoclonal antibodies (therapeutic mAb) and adoptive immunotherapy have become increasingly more common in the treatment of hematolymphoid neoplasms, with practical implications for diagnostic flow cytometry. Their use can reduce the sensitivity of flow cytometry for populations of interest owing to downregulation/loss of the target antigen, competition for the target antigen, or lineage switch. Expanded flow panels, marker redundancy, and exhaustive gating strategies can overcome this limitation. Therapeutic mAb have been reported to cause pseudo-light chain restriction, and awareness of this potential artifact is key. Established guidelines do not yet exist for antigen expression by flow cytometry for therapeutic purposes.

Safety and efficacy of co-administration of CD19 and CD22 CAR-T cells in children with B-ALL relapse after CD19 CAR-T therapy

BACKGROUND

CD19-targeted chimeric antigen receptor T-cell (CAR-T) therapy has shown remarkable efficacy in treating relapsed or refractory pediatric B-lineage acute lymphoblastic leukemia (B-ALL). However, poor results are obtained when the same product is reused in patients who relapse after CAR-T. Therefore, there is a need to explore the safety and efficacy of co-administration of CD19- and CD22-targeted CAR-T as a salvage second CAR-T therapy (CART2) in B-ALL patients who relapse after their first CD19 CAR-T treatment (CART1).

METHODS

In this study, we recruited five patients who relapsed after CD19-targeted CAR-T. CD19- and CD22-CAR lentivirus-transfected T cells were cultured separately and mixed before infusion in an approximate ratio of 1:1. The total dose range of CD19 and CD22 CAR-T was 4.3 × 10⁶-1.5 × 10⁷/kg. Throughout the trial, we evaluated the patients' clinical responses, side effects, and the expansion and persistence of CAR-T cells.

RESULTS

After CART2, all five patients had minimal residual disease (MRD)-negative complete remission (CR). The 6- and 12-month overall survival (OS) rates were 100%. The median follow-up time was 26.3 months. Three of the five patients bridged to consolidated allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CART2 and remained in MRD-negative CR at the cut-off time. In patient No. 3 (pt03), CAR-T cells were still detected in the peripheral blood (PB) at 347 days post-CART2. Cytokine release syndrome (CRS) only occurred with a grade of ≤ 2, and no patients experienced symptoms of neurologic toxicity during CART2.

CONCLUSIONS

Mixed infusion of CD19- and CD22-targeted CAR-T cells is a safe and effective regimen for children with B-ALL who relapse after prior CD19-targeted CAR-T therapy. Salvage CART2 provides an opportunity for bridging to transplantation and long-term survival.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2000032211. Retrospectively registered: April 23, 2020.

Coadministration of CD19- and CD22-Directed Chimeric Antigen Receptor T-Cell Therapy in Childhood B-Cell Acute Lymphoblastic Leukemia: A Single-Arm, Multicenter, Phase II Trial

PURPOSE

We determined the safety and efficacy of coadministration of CD19- and CD22-chimeric antigen receptor (CAR) T cells in patients with refractory disease or high-risk hematologic or isolated extramedullary relapse of B-acute lymphoblastic leukemia.

PATIENTS AND METHODS

This phase II trial enrolled 225 evaluable patients age ≤ 20 years between September 17, 2019, and December 31, 2021. We first conducted a safety run-in stage to determine the recommended dose. After interim analysis of the first 30 patients treated (27 at the recommended dose) showing that the treatment was safe and effective, the study enrolled additional patients according to the study design.

RESULTS

Complete remission was achieved in 99.0% of the 194 patients with refractory leukemia or hematologic relapse, all negative for minimal residual disease. Their overall 12-month event-free survival (EFS) was 73.5% (95% CI, 67.3 to 80.3). Relapse occurred in 43 patients (24 with CD19+/CD22+ relapse, 16 CD19-/CD22+, one CD19-/CD22-, and two unknown). Consolidative transplantation and persistent B-cell aplasia at 6 months were associated with favorable outcomes. The 12-month EFS was 85.0% (95% CI, 77.2 to 93.6) for the 78 patients treated with transplantation and 69.2% (95% CI, 60.8 to 78.8) for the 116 nontransplanted patients (P = .03, time-dependent covariate Cox model). All 25 patients with persistent B-cell aplasia at 6 months remained in remission at 12 months. The 12-month EFS for the 20 patients with isolated testicular relapse was 95.0% (95% CI, 85.9 to 100), and for the 10 patients with isolated CNS relapse, it was 68.6% (95% CI, 44.5 to 100). Cytokine release syndrome developed in 198 (88.0%) patients, and CAR T-cell neurotoxicity in 47 (20.9%), resulting in three deaths.

CONCLUSION

CD19-/CD22-CAR T-cell therapy achieved relatively durable remission in children with relapsed or refractory B-acute lymphoblastic leukemia, including those with isolated or combined extramedullary relapse.

[Media: see text].

Case report: Sandwich therapy of CAR-T combined with ASCT: Sequential CAR-T cell therapy with ASCT after remission with CAR-T therapy caused long-term survival in a patient with relapsed/refractory Burkitt’s lymphoma with TP53 mutations

Burkitt’s lymphoma (BL) with TP53 mutation often has poor outcome after standard chemoimmunotherapy. Adoptive chimeric antigen receptor (CAR)-T cell therapy may be a new paradigm for treating refractory/relapsed (r/r) BL, but its therapeutic effects remain inconclusive. Here, we report a patient with r/r BL who failed to achieve complete remission (CR) and progressed rapidly after multiple protocol chemotherapy. The patient achieved CR with CAR19 and CAR22 T-cell cocktail therapy and obtained long-term disease-free survival after autologous hematopoietic stem cells (ASCT) and subsequential CAR19 and CAR22 T-cell cocktail therapy. The clinical evolution and genetic features of this case may provide some guidance for CAR-T therapy in overcoming relapses associated with TP53 gene mutations.

Emerging phagocytosis checkpoints in cancer immunotherapy

Cancer immunotherapy, mainly including immune checkpoints-targeted therapy and the adoptive transfer of engineered immune cells, has revolutionized the oncology landscape as it utilizes patients' own immune systems in combating the cancer cells. Cancer cells escape immune surveillance by hijacking the corresponding inhibitory pathways via overexpressing checkpoint genes. Phagocytosis checkpoints, such as CD47, CD24, MHC-I, PD-L1, STC-1 and GD2, have emerged as essential checkpoints for cancer immunotherapy by functioning as "don't eat me" signals or interacting with "eat me" signals to suppress immune responses. Phagocytosis checkpoints link innate immunity and adaptive immunity in cancer immunotherapy. Genetic ablation of these phagocytosis checkpoints, as well as blockade of their signaling pathways, robustly augments phagocytosis and reduces tumor size. Among all phagocytosis checkpoints, CD47 is the most thoroughly studied and has emerged as a rising star among targets for cancer treatment. CD47-targeting antibodies and inhibitors have been investigated in various preclinical and clinical trials. However, anemia and thrombocytopenia appear to be formidable challenges since CD47 is ubiquitously expressed on erythrocytes. Here, we review the reported phagocytosis checkpoints by discussing their mechanisms and functions in cancer immunotherapy, highlight clinical progress in targeting these checkpoints and discuss challenges and potential solutions to smooth the way for combination immunotherapeutic strategies that involve both innate and adaptive immune responses.

Small-Molecule Compounds Boost CAR-T Cell Therapy in Hematological Malignancies

OPINION STATEMENT

Although chimeric antigen receptor T cell immunotherapy has been successfully applied in patients with hematological malignancies, several obstacles still need to be overcome, such as high relapse rates and side effects. Overcoming the limitations of CAR-T cell therapy and boosting the efficacy of CAR-T cell therapy are urgent issues that must be addressed. The exploration of small-molecule compounds in combination with CAR-T cell therapies has achieved promising success in pre-clinical and clinical studies in recent years. Protein kinase inhibitors, demethylating drugs, HDAC inhibitors, PI3K inhibitors, immunomodulatory drugs, Akt inhibitors, mTOR inhibitors, and Bcl-2 inhibitors exhibited potential synergy in combination with CAR-T cell therapy. In this review, we will discuss the recent application of these combination therapies for improved outcomes of CAR-T cell therapy.

Challenges and optimal strategies of CAR T therapy for hematological malignancies

ABSTRACT

Remarkable improvement relative to traditional approaches in the treatment of hematological malignancies by chimeric antigen receptor (CAR) T-cell therapy has promoted sequential approvals of eight commercial CAR T products within last 5 years. Although CAR T cells' productization is now rapidly boosting their extensive clinical application in real-world patients, the limitation of their clinical efficacy and related toxicities inspire further optimization of CAR structure and substantial development of innovative trials in various scenarios. Herein, we first summarized the current status and major progress in CAR T therapy for hematological malignancies, then described crucial factors which possibly compromise the clinical efficacies of CAR T cells, such as CAR T cell exhaustion and loss of antigen, and finally, we discussed the potential optimization strategies to tackle the challenges in the field of CAR T therapy.

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.

CAR-T therapy followed by allogeneic hematopoietic stem cell transplantation for refractory/relapsed acute B lymphocytic leukemia: Long-term follow-up results

Background

Patients with refractory/relapsed (r/r) acute B lymphocytic leukemia (B-ALL) can achieve complete response (CR) after chimeric antigen receptor T-cell (CAR-T) therapy, but recurrence occurs in the short term. To reduce recurrence and improve survival, CAR-T therapy followed by transplantation is a feasible option. We analyzed the long-term follow-up outcomes and the risk factors for allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CR by CAR-T therapy in this study.

Methods

A total of 144 patients who underwent allo-HSCT after CAR-T therapy in our hospital were enrolled in this study. Target gene analysis was performed in 137 r/r B-ALL patients receiving allo-HSCT after CR by CAR-T therapy. Among the 137 patients, 87 were evaluated for germline predisposition gene mutations, and 92 were evaluated for tumor somatic gene mutations using NGS. The clinical factors, germline predisposition gene and somatic gene mutations associated with the prognosis of patients receiving transplantation after CAR-T therapy were analyzed using univariate Cox regression. Factors related to disease-free survival (DFS) and overall survival (OS) were analyzed using multivariate Cox regression analysis.

Results

In 137 r/r B-ALL patients, the 2-year cumulative incidence of recurrence (CIR), OS and DFS in patients receiving allo-HSCT after CAR-T therapy was 31.5%, 71.4%, and 60.5%, respectively. The 2-year OS and DFS in MRD-negative patients were 80.9% and 69.3%, respectively. Univariate Cox analysis showed that pretransplant MRD positivity, fungal infection, germline EP300 mutation and somatic TP53 mutation were associated with a poor prognosis after transplantation; a TBI-based regimen was a protective factor for survival and recurrence after transplantation. Multivariate Cox regression analysis showed that the TBI-based regimen was an independent protective factor for DFS, fungal infection and MRD positivity were independent risk factors for DFS, and tumor somatic TP53 mutation and germline EP300 mutation were independent risk factors for DFS and OS.

Conclusion

Germline EP300 mutation and tumor somatic TP53 mutation are poor prognostic factors for posttransplant recurrence and survival in r/r B-ALL patients achieving CR after CAR-T therapy. The prognostic risk factors should be considered in adjusting treatment strategies to improve the efficacy of clinical diagnosis and treatment.

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.

Efficacy and safety of CD22-specific and CD19/CD22-bispecific CAR-T cell therapy in patients with hematologic malignancies: A systematic review and meta-analysis

Background

CD22 single and CD19/CD22 bispecific targeted chimeric antigen receptor T (CAR-T) cell therapy are promising immunotherapy modalities for the treatment of hematologic malignancies. The aim of this study was to assess the efficacy and safety of CD22 and CD19/CD22 targeted CAR-T cell therapy by summarizing the existing evidence.

Methods

Electronic databases including PubMed, Embase, and Scopus were comprehensively searched from inception up to November 30, 2022. Pooled response rates and minimal residual disease (MRD) negative response rates, cytokine release syndrome (CRS) rates and neurotoxicity rates were calculated. Subgroup analysis was performed based on the type of immunotherapy.

Results

Ten clinical studies including 194 patients with hematologic malignancies were included after a systematical screening of literature. The pooled complete response (CR) rates of CD22 and CD19/CD22 CAR-T cell therapy for relapsed or refractory B-cell lymphoblastic leukemia (B-ALL) were 0.75 (95% CI: 0.60 - 0.88) and 0.87 (95% CI: 0.76 - 0.96). The overall MRD negative response rates of CD22 and CD19/CD22 CAR-T were 0.54 (95% CI: 0.42 - 0.66) and 0.91 (95% CI: 0.47 - 0.88). Pooled CRS rates of CD22 targeted and CD19/CD22 targeted immunotherapy were 0.92 (95% CI: 0.82 - 0.98) and 0.94 (95% CI: 0.82 - 1.00), respectively.

Conclusion

Both CD22 and CD19/CD22 CAR-T immunotherapy demonstrated favorable efficacy and acceptable adverse events in the treatment of hematologic malignancies. Well-designed and large sample-sized clinical trials are warranted.

Dose-response correlation for CAR-T cells: a systematic review of clinical studies

The potential of chimeric antigen receptor (CAR) T cells to successfully treat hematological cancers is widely recognized. Multiple CAR-T cell therapies are currently under clinical development, with most in early stage, during which dose selection is a key goal. The objective of this review is to address the question of dose-dependent effects on response and/or toxicity from available CAR-T cell clinical trial data. For that purpose, systematic literature review of studies published between January 2010 and May 2022 was performed on PubMed and Embase to search clinical studies that evaluated CAR-T cells for hematological cancers. Studies published in English were considered. Studies in children (age <18 years), solid tumors, bispecific CAR-T cells and CAR-T cell cocktails were excluded. As a result, a total of 74 studies met the inclusion criteria. Thirty-nine studies tested multiple dose levels of CAR-T cells with at least >1 patient at each dose level. Thirteen studies observed dose-related increase in disease response and 23 studies observed dose-related increase in toxicity across a median of three dose levels. Optimal clinical efficacy was seen at doses 50-100 million cells for anti-CD19 CAR-T cells and >100 million cells for anti-BCMA CAR-T cells in majority of studies. The findings suggest, for a given construct, there exists a dose at which a threshold of optimal efficacy occurs. Dose escalation may reveal increasing objective response rates (ORRs) until that threshold is reached. However, when ORR starts to plateau despite increasing dose, further dose escalation is unlikely to result in improved ORR but is likely to result in higher incidence and/or severity of mechanistically related adverse events.

Synergistic combination of targeted nano-nuclear-reactors and anti-PD-L1 nanobodies evokes persistent T cell immune activation for cancer immunotherapy

BACKGROUND

Antitumor T cell immunotherapy as a novel cancer therapeutic strategy has shown enormous promise. However, the tumor microenvironment (TME) is characterized by the low immunogenicity, hypoxia, and immunosuppressive condition that dramatically limit effective T cell immunotherapy. Thus, an ideal immunotherapy strategy that is capable of reversing the immunosuppressive TME is highly imperative.

RESULTS

In this article, we reported that Fe-doped and doxorubicin (DOX) loaded HA@Cu_2-XS-PEG (PHCN) nanomaterials were rationally designed as targeted Fe-PHCN@DOX nano-nuclear-reactors, which evoked persistent T cell immune response together with anti-PD-L1 nanobodies. It was confirmed that nano-nuclear-reactors displayed strong nanocatalytic effect for effective antitumor effects. Consequently, they maximized the immunogenic cell death (ICD) effect for antigen presentation and then stimulated T cell activation. In addition, Fe-PHCN@DOX could reprogram M2-phenotype tumor-associated macrophages (TAMs) into M1-phenotype TAMs by relieving tumor hypoxia. Meanwhile, blockade of the anti-PD-L1 nanobody promoted T cell activation through targeting the PD-1/PD-L1 immunosuppressive pathway. Notably, in vivo tumor therapy verified that this nano-nuclear-reactor could be used as an excellent immunotherapy nanoplatform for tumor eradication and metastasis prevention with nanobody.

CONCLUSIONS

Our findings demonstrated that nano-nuclear-reactors in combination with nanobody could evoke persistent T cell immune activation, suggesting them potential as a promising immunotherapy option for reversing immunosuppressive immune-cold tumors.

Chimeric antigen receptor T cells applied to solid tumors

Chimeric antigen receptor T cell (CAR-T) therapy is novel tumor immunotherapy that enables autologous T to express synthetic receptors to specifically recognize the surface tumor-associated antigens for exerting subsequent antitumor effects, and eliminating the resistance, metastases and recurrence of cancer. Although CAR T cells have exhibited success in eradicating hematologic malignancies, their applications to solid tumors has not yet been achieved due to obstacles such as the immune-suppressor tumor microenvironment and lack of tumor specific target antigens. In this review, we presented advancements in the development of CAR T cell therapy in solid tumors, and offered a brief summary of the challenges, as well as novel engineering and pharmaceutical interventions to overcome these barriers. Looking forward, we discussed the latest studies which are expected to reach the clinicals in the next few years, including CRISPR screens-based CAR modification and CAR T cells driven from progenitor-like T cells. Collectively, this review may inspire researchers and clinicians to develop clinical available strategies of CAR T cell therapies in solid tumor.

Tumor buster - where will the CAR-T cell therapy 'missile' go?

Chimeric antigen receptor (CAR) T cell (CAR-T cell) therapy based on gene editing technology represents a significant breakthrough in personalized immunotherapy for human cancer. This strategy uses genetic modification to enable T cells to target tumor-specific antigens, attack specific cancer cells, and bypass tumor cell apoptosis avoidance mechanisms to some extent. This method has been extensively used to treat hematologic diseases, but the therapeutic effect in solid tumors is not ideal. Tumor antigen escape, treatment-related toxicity, and the immunosuppressive tumor microenvironment (TME) limit their use of it. Target selection is the most critical aspect in determining the prognosis of patients receiving this treatment. This review provides a comprehensive summary of all therapeutic targets used in the clinic or shown promising potential. We summarize CAR-T cell therapies’ clinical trials, applications, research frontiers, and limitations in treating different cancers. We also explore coping strategies when encountering sub-optimal tumor-associated antigens (TAA) or TAA loss. Moreover, the importance of CAR-T cell therapy in cancer immunotherapy is emphasized.

CAR‐T therapy as a consolidation in remission B‐ALL patients with poor prognosis

Background

To date, almost all studies regarding chimeric antigen receptor (CAR)‐T cell therapy for B‐cell acute lymphoblastic leukemia (B‐ALL) were performed in refractory/relapsed (r/r) or minimal residual disease‐positive patients. CAR‐T therapy in remission patients has not been reported.

Aim

To observe the treatment outcome of CAR‐T cells for remission B‐ALL patients with poor prognosis.

Methods and Results

CAR‐T treatment was applied to two B‐ALL patients in remission status who had poor prognostic factors and refused transplantation, and one case was unable to accept standard chemotherapy owing to multiple complications. The procedure of CAR‐T therapy in these two remission patients was the same as that in r/r B‐ALL patients. Lentiviral vectors encoding second generation CARs composed of CD3ζ and 4‐1BB were used to produce CAR‐T cells. Lymphodepleting agents fludarabine and cyclophosphamide were administered prior to cell infusion. Grade I cytokine release syndrome occurred after each T‐cell infusion and there was no neurotoxicity. CAR‐T treatment followed by non‐intensive maintenance chemotherapy and targeted drugs allowed both patients to obtain a long‐term event‐free survival of more than three and a half years without transplantation.

Conclusions

CAR‐T therapy could be used in high‐risk B‐ALL patients as a consolidation to avoid transplantation, the combination of CAR‐T and following maintenance therapy may be better than CAR‐T alone for durable remission.

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.

CAR-T Cell Therapy in Hematological Malignancies: Current Opportunities and Challenges

Chimeric antigen receptor T (CAR-T) cell therapy represents a major breakthrough in cancer treatment, and it has achieved unprecedented success in hematological malignancies, especially in relapsed/refractory (R/R) B cell malignancies. At present, CD19 and BCMA are the most common targets in CAR-T cell therapy, and numerous novel therapeutic targets are being explored. However, the adverse events related to CAR-T cell therapy might be serious or even life-threatening, such as cytokine release syndrome (CRS), CAR-T-cell-related encephalopathy syndrome (CRES), infections, cytopenia, and CRS-related coagulopathy. In addition, due to antigen escape, the limited CAR-T cell persistence, and immunosuppressive tumor microenvironment, a considerable proportion of patients relapse after CAR-T cell therapy. Thus, in this review, we focus on the progress and challenges of CAR-T cell therapy in hematological malignancies, such as attractive therapeutic targets, CAR-T related toxicities, and resistance to CAR-T cell therapy, and provide some practical recommendations.

Long-Term Safety and Efficacy of CD19 Humanized Selective CAR-T Therapy in B-ALL Patients Who Have Previously Received Murine-Based CD19 CAR-T Therapy

Murine-based CD19 CAR-T (CD19m CAR-T) therapy can lead to a relatively high CR rate when administered to B-ALL patients for the first time. However, the DOR is sub-optimal and a subset of patients even show primary resistance to CD19m CAR-T. To address these issues, we employed a humanized selective CD19CAR-T (CD19hs CAR-T) and evaluated the long-term safety and efficacy of treating 8 R/R B-ALL patients who had relapsed or failed to achieve CR following CD19m CAR-T infusion (Clinical trials’ number: ChiCTR1800014761 and ChiCTR1800017439). Of the 8 patients, 7 achieved CR on Day 30 after the 1^st infusion of CD19hs CAR-T. The median CRS grade was 1 without significant neurotoxicity seen in any of the 8 patients. The median DOR was 11 months, significantly longer than the DOR following CD19mCAR-T infusions. Anti-CAR antibodies were induced in patients who had received prior CD19m CAR-T infusions but not in those following a single or repeated CD19hsCAR-T treatment, which probably had contributed to the sub-optimal DOR and/or failure of effective response in these patients. CD19hs CAR-T, in contrast, induced low immunogenicity compared with CD19m CAR-T, suggesting that a repeat dosing strategy might be feasible and efficacious for patients who have relapsed and/or show primary resistance to CD19m CAR-T therapy. In this clinical study, CD19hs CAR-T showed a significant clinical efficacy with mild side effect among patients with R/R B-ALL who had previously received CD19m CAR-T.

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.

Modulating tumor physical microenvironment for fueling CAR-T cell therapy

Chimeric antigen receptor (CAR) T cell therapy has achieved unprecedented clinical success against hematologic malignancies. However, the transition of CAR-T cell therapies for solid tumors is limited by heterogenous antigen expression, immunosuppressive microenvironment (TME), immune adaptation of tumor cells and impeded CAR-T-cell infiltration/transportation. Recent studies increasingly reveal that tumor physical microenvironment could affect various aspects of tumor biology and impose profound impacts on the antitumor efficacy of CAR-T therapy. In this review, we discuss the critical roles of four physical cues in solid tumors for regulating the immune responses of CAR-T cells, which include solid stress, interstitial fluid pressure, stiffness and microarchitecture. We highlight new strategies exploiting these features to enhance the therapeutic potency of CAR-T cells in solid tumors by correlating with the state-of-the-art technologies in this field. A perspective on the future directions for developing new CAR-T therapies for solid tumor treatment is also provided.