Anti-CD19 CAR T Cells That Secrete a Biparatopic Anti-CLEC12A Bridging Protein Have Potent Activity Against Highly Aggressive Acute Myeloid Leukemia In Vitro and In Vivo

Modular (universal) CAR-T platforms in vivo: a comprehensive systematic review

Background

Modular (universal) CAR T-platforms were developed to combat the limitations of traditional CAR-T therapy, allowing for multiple targeting of tumor-associated antigens and the ability to control CAR-T cell activity. The modular CAR-T platform consists of a universal receptor (signaling module) that recognizes an adapter molecule on the soluble module, which is responsible for antigen recognition. Multiple platforms have been developed over the last 12 years, and some of them have entered the clinical trial phase. This systematic review seeks to evaluate the different parameters of modular CAR-T platforms performance in animal models.

Methods

A systematic search of literature in the PubMed database and in Google Scholar and BASE (Bielefeld Academic Search Engine) search engines was performed according to predefined eligibility criteria. All studies conducted on xenograft mouse models with any variant of modular CAR-T platforms were included. Forest plots were generated for visual presentation of the extracted quantitative findings (standardized mean difference (SMD) and median survival rate (MSR)).

Results

A total of 33 studies employing 15 different modular CAR-T platforms were included. The platforms varied in terms of CAR-T cells, soluble module doses, and their frequency of administration. The studies showed a reduction in tumor burden and in tumor volume compared to the combined negative group. In comparison with the positive control group, there was no significant change in tumor burden or volume. In all the included studies the experimental group had a higher survival probability compared to the combined negative group at the study endpoint, with no significant difference in survival rate compared to the positive control group.

Conclusion

The modular CAR-T platforms are generally effective and are a valuable addition to the arsenal of CAR therapy.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/ PROSPERO, identifier CRD42023443984.

Biparatopic antibodies: therapeutic applications and prospects

Biparatopic antibodies (bpAbs) bind distinct, non-overlapping epitopes on an antigen. This unique binding mode enables new mechanisms of action beyond monospecific and bispecific antibodies (bsAbs) that can make bpAbs effective therapeutics for various indications, including oncology and infectious diseases. Biparatopic binding can lead to superior affinity and specificity, promote antagonism, lock target conformation, and result in higher-order target clustering. Such antibody-target complexes can elicit strong agonism, increase immune effector function, or result in rapid target downregulation and lysosomal trafficking. These are not only attractive properties for therapeutic antibodies but are increasingly being explored for other modalities such as antibody-drug conjugates, T-cell engagers and chimeric antigen receptors. Recent advances in bpAb engineering have enabled the construction of ever more sophisticated formats that are starting to show promise in the clinic.

Chimeric antigen receptor T (CAR-T) cells: Novel cell therapy for hematological malignancies

Over the last decade, the emergence of several novel therapeutic approaches has changed the therapeutic perspective of human malignancies. Adoptive immunotherapy through chimeric antigen receptor T cell (CAR-T), which includes the engineering of T cells to recognize tumor-specific membrane antigens and, as a result, death of cancer cells, has created various clinical benefits for the treatment of several human malignancies. In particular, CAR-T-cell-based immunotherapy is known as a critical approach for the treatment of patients with hematological malignancies such as acute lymphoblastic leukemia (ALL), multiple myeloma (MM), chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML), Hodgkin lymphoma (HL), and non-Hodgkin's lymphoma (NHL). However, CAR-T-cell therapy of hematological malignancies is associated with various side effects. There are still extensive challenges in association with further progress of this therapeutic approach, from manufacturing and engineering issues to limitations of applications and serious toxicities. Therefore, further studies are required to enhance efficacy and minimize adverse events. In the current review, we summarize the development of CAR-T-cell-based immunotherapy and current clinical antitumor applications to treat hematological malignancies. Furthermore, we will mention the current advantages, disadvantages, challenges, and therapeutic limitations of CAR-T-cell therapy.

CAR-T Engager proteins optimize anti-CD19 CAR-T cell therapies for lymphoma

B cell lymphoma therapy has been transformed by CD19-targeting cellular therapeutics that induce high clinical response rates and impressive remissions in relapsed and refractory patients. However, approximately half of all patients who respond to CD19-directed cell therapy relapse, the majority within 6 months. One characteristic of relapse is loss or reduction of CD19 expression on malignant B cells. We designed a unique therapeutic to prevent and reverse relapses due to lost or reduced CD19 expression. This novel biologic, a CAR T Engager, binds CD20 and displays the CD19 extracellular domain. This approach increases the apparent CD19 antigen density on CD19-positive/CD20-positive lymphoma cells, and prevents antigen-loss induced relapse, as CD19 bound to CD20 remains present on the cell surface. We demonstrate that this novel therapeutic prevents and reverses lymphoma relapse in vitro and prevents CD19-negative lymphoma growth and relapse in vivo.

Secretory co-factors in next-generation cellular therapies for cancer

Since chimeric antigen receptor (CAR) T-cell therapies for hematologic malignancies were approved by the U.S. Food and Drug Administration, numerous "next-generation" CAR T cells have been developed to improve their safety, efficacy, and applicability. Although some of these novel therapeutic strategies are promising, it remains difficult to apply these therapies to solid tumors and to control adverse effects, such as cytokine release syndrome and neurotoxicity. CAR T cells are generated using highly scalable genetic engineering techniques. One of the major strategies for producing next-generation CAR T cells involves the integration of useful co-factor(s) into the artificial genetic design of the CAR gene, resulting in next-generation CAR T cells that express both CAR and the co-factor(s). Many soluble co-factors have been reported for CAR T cells and their therapeutic effects and toxicity have been tested by systemic injection; therefore, CAR T cells harnessing secretory co-factors could be close to clinical application. Here, we review the various secretory co-factors that have been reported to improve the therapeutic efficacy of CAR T cells and ameliorate adverse events. In addition, we discuss the different co-factor expression systems that have been used to optimize their beneficial effects. Altogether, we demonstrate that combining CAR T cells with secretory co-factors will lead to next-generation CAR T-cell therapies that can be used against broader types of cancers and might provide advanced tools for more complicated synthetic immunotherapies.

CLEC12A plays an important role in immunomodulatory function and prognostic significance of patients with acute myeloid leukemia

The physiological function and prognostic significance of C-type lectin domain family 12 member A (CLEC12A) in acute myeloid leukemia (AML) patients are unclear. CLEC12A transcriptional expression in a variety of tumors from several public databases was collected and compared. We found that CLEC12A was highly expressed in AML cell lines and in tissues from AML patients and a higher CLEC12A expression in leukemia stem cells. CLEC12A low expression was associated with poor prognosis in the chemotherapy-only group and high CLEC12A expression may benefit from autologous or allogeneic hematopoietic stem cell transplantation (HSCT). CLEC12A expression was positively correlated with infiltrating levels of type 2 macrophages and monocytes and negatively associated with NK cells and regulatory T cells in AML. CLEC12A high was positively associated with immune checkpoint genes as well as macrophage associated genes. CLEC12A is an ideal chimeric antigen receptor T-cell (CAR-T) therapy target for AML and its expression level was closely linked to treatment response and patients' survival outcome. CLEC12A plays an important immunomodulatory role in AML.

Optimization of Donor Lymphocyte Infusion for AML Relapse After Allo-HCT in the Era of New Drugs and Cell Engineering

Donor lymphocyte infusion (DLI) is a key strategy for the treatment of AML relapse after allogeneic hematopoietic cell transplantation (allo-HCT) and has been used for either prophylactic, pre-emptive, or therapeutic purposes. However, the prognosis of these patients remains dismal even after DLI infusion (2-year overall survival, ~25%), and the efficacy is achieved at the cost of toxicities such as graft-versus-host (GVH) disease. Attempts to optimize DLI efficacy and safety, such as dose/timing modification and the use of cytoreduction, before DLI have been performed previously. Recently, a great number of novel targeted and immunomodulatory agents have emerged. Some of them, such as hypomethylating agents, FLT3 and Bcl-2 inhibitors, have been used in combination with DLI, aiming to enhance the graft-versus-leukemia effect. Moreover, manipulation of the DLI graft through cell selection (e.g., donor NK cells) or cell engineering (donor CAR-T cells) has shown potentially superior anti-tumor effects but less GVH effect than conventional DLI in clinical trials. This review summarizes the recent advances on the use of DLI for the prophylaxis/treatment of AML relapse and discusses future strategies which may further improve the treatment efficacy.