Adapter CAR T Cell Therapy for the Treatment of B-Lineage Lymphomas

CAR T cells re-directed by a rationally designed human peptide tag demonstrate efficacy in preclinical models

Currently, only a few chimeric antigen receptor (CAR) T cell therapies have been approved by the Food and Drug Administration and European Medicines Agency for the treatment of B-cell malignancies. To enable broader application of the CAR T cell technology in other indications, improved control and flexible targeting of multiple tumor antigens are required. Here, we developed a novel adapter CAR (AdCAR) T cell platform for flexible targeting of multiple tumor antigens. This platform is based on a short peptide tag derived from an interdomain region of fibroblast growth factor receptor 2 (FGFR2), commonly mutated in cancer. To select AdCARs specific for mutated FGFR2-derived peptide tags, a multistep pooled screening approach in primary T cells was employed, incorporating MACS separation and next-generation sequencing. The resulting AdCAR was highly specific for the FGFR2-derived peptide tag. Using different in vitro and in vivo model systems, the activity of AdCAR T cells was shown to be strictly dependent on the presence of the adapter and corresponding target antigen. Moreover, AdCAR T cells could be redirected to different target antigens by the addition of respective adapter molecules (AM). Finally, in situ expression of functional AM in primary T cells under control of a drug-inducible promoter system was demonstrated, highlighting the potential for controlling the activity of AdCAR T cells by cellular micropharmacies.

Engineering signalling pathways in mammalian cells

In mammalian cells, signalling pathways orchestrate cellular growth, differentiation and survival, as well as many other processes that are essential for the proper functioning of cells. Here we describe cutting-edge genetic-engineering technologies for the rewiring of signalling networks in mammalian cells. Specifically, we describe the recombination of native pathway components, cross-kingdom pathway transplantation, and the development of de novo signalling within cells and organelles. We also discuss how, by designing signalling pathways, mammalian cells can acquire new properties, such as the capacity for photosynthesis, the ability to detect cancer and senescent cell markers or to synthesize hormones or metabolites in response to chemical or physical stimuli. We also review the applications of mammalian cells in biocomputing. Technologies for engineering signalling pathways in mammalian cells are advancing basic cellular biology, biomedical research and drug discovery.

Rational combinatorial targeting by adapter CAR-T-cells (AdCAR-T) prevents antigen escape in acute myeloid leukemia

Targeting AML by chimeric antigen receptor T-cells (CAR-T) is challenging due to the promiscuous expression of AML-associated antigens in healthy hematopoiesis and high degree of inter- and intratumoral heterogeneity. Here, we present single-cell expression data of AML-associated antigens in 30 primary pediatric AML samples. We identified CD33, CD38, CD371, IL1RAP and CD123 as the most frequently expressed. Notably, high variability was observed not only across the different patient samples but also among leukemic cells of the same patient suggesting the necessity of multiplexed targeting approaches. To address this need, we utilized our modular Adapter CAR (AdCAR) platform, enabling precise qualitative and quantitative control over CAR-T-cell function. We show highly efficient and target-specific activity for newly generated adapter molecules (AMs) against CD33, CD38, CD123, CD135 and CD371, both in vitro and in vivo. We reveal that inherent intratumoral heterogeneity in antigen expression translates into antigen escape and therapy failure to monotargeted CAR-T therapy. Further, we demonstrate in PDX models that rational combinatorial targeting by AdCAR-T-cells can cure heterogenic disease. In conclusion, we elucidate the clinical relevance of heterogeneity in antigen expression in pediatric AML and present a novel concept for precision immunotherapy by combinatorial targeting utilizing the AdCAR platform.

UniCAR T-Cell Potency-A Matter of Affinity between Adaptor Molecules and Adaptor CAR T-Cells?

Although Chimeric Antigen Receptor (CAR) T-cells have shown high efficacy in hematologic malignancies, they can cause severe to life-threatening side effects. To address these safety concerns, we have developed adaptor CAR platforms, like the UniCAR system. The redirection of UniCAR T-cells to target cells relies on a Target Module (TM), containing the E5B9 epitope and a tumor-specific binding moiety. Appropriate UniCAR-T activation thus involves two interactions: between the TM and the CAR T-cell, and the TM and the target cell. Here, we investigate if and how alterations of the amino acid sequence of the E5B9 UniCAR epitope impact the interaction between TMs and the UniCAR. We identify the new epitope E5B9L, for which the monoclonal antibody 5B9 has the greatest affinity. We then integrate the E5B9L peptide in previously established TMs directed to Fibroblast Activation Protein (FAP) and assess if such changes in the UniCAR epitope of the TMs affect UniCAR T-cell potency. Binding properties of the newly generated anti-FAP-E5B9L TMs to UniCAR and their ability to redirect UniCAR T-cells were compared side-by-side with the ones of anti-FAP-E5B9 TMs. Despite a substantial variation in the affinity of the different TMs to the UniCAR, no significant differences were observed in the cytotoxic and cytokine-release profiles of the redirected T-cells. Overall, our work indicates that increasing affinity of the UniCAR to the TM does not play a crucial role in such adaptor CAR system, as it does not significantly impact the potency of the UniCAR T-cells.

Universal CAR 2.0 to overcome current limitations in CAR therapy

Chimeric antigen receptor (CAR) T cell therapy has effectively complemented the treatment of advanced relapsed and refractory hematological cancers. The remarkable achievements of CD19- and BCMA-CAR T therapies have raised high expectations within the fields of hematology and oncology. These groundbreaking successes are propelling a collective aspiration to extend the reach of CAR therapies beyond B-lineage malignancies. Advanced CAR technologies have created a momentum to surmount the limitations of conventional CAR concepts. Most importantly, innovations that enable combinatorial targeting to address target antigen heterogeneity, using versatile adapter CAR concepts in conjunction with recent transformative next-generation CAR design, offer the promise to overcome both the bottleneck associated with CAR manufacturing and patient-individualized treatment regimens. In this comprehensive review, we delineate the fundamental prerequisites, navigate through pivotal challenges, and elucidate strategic approaches, all aimed at paving the way for the future establishment of multitargeted immunotherapies using universal CAR technologies.

Precision Immunotherapy Utilizing Adapter CAR-T Cells (AdCAR-T) in Metastatic Breast Cancer Leads to Target Specific Lysis

A frequent symptom of metastasized breast cancer (BC) includes the development of malignant pleural effusion (MPE), which contains malignant cells derived from the primary tumor site. The poor prognosis of MPE in metastasized BC indicates the necessity for dependable precision oncology and the importance of models representing the heterogenous nature of metastatic BC. In this study, we cultured MPE-derived metastatic tumor cells from four advanced BC patients using organoid technology. We assessed the expression of tumor-associated antigens on MPE-derived organoid lines by flow cytometry (FC). Based on an individual antigen expression pattern, patient-derived organoids were treated with adapter CAR-T cells (AdCAR-T) and biotinylated monoclonal antibodies targeting CD276, HER2, EGFR, TROP2, or EpCAM. Co-culture assays revealed specific organoid lysis by AdCAR-T depending on individual antigen expression patterns. Our results demonstrate that MPE-derived organoids can serve as a reliable tool for assessing the efficacy of AdCAR-T on metastatic BC in a patient-individualized manner. This approach could potentially be applied in a preclinical setting to instruct therapy decisions. Further, our study demonstrates the feasibility of precision immunotherapy utilizing AdCAR-T to target patient-individualized antigen patterns.

CAR designs for solid tumors: overcoming hurdles and paving the way for effective immunotherapy

Chimeric antigen receptor T cell (CAR-T) therapy has revolutionized immunotherapy by modifying patients' immune cells genetically. By expressing CARs, these modified cells can specifically identify and eliminate tumor cells. The success of CAR-T therapy in hematological malignancies, such as leukemia and lymphoma, has been remarkable. Numerous studies have reported improved patient outcomes and increased survival rates. However, the application of CAR-T therapy in treating solid tumors faces significant challenges. Solid tumors possess complex microenvironments containing stromal cells, extracellular matrix components, and blood vessels. These factors can impede the infiltration and persistence of CAR-T cells within the tumor. Additionally, the lack of target antigens exclusively expressed on tumor cells raises concerns about off-target effects and potential toxicity. This review aims to discuss advancements achieved by CAR-T therapy in solid tumors and the clinical outcomes in the realm of solid tumors.

Immunotherapy for Acute Myeloid Leukemia: Current Trends, Challenges, and Strategies

BACKGROUND

In the past decade, there have been significant breakthroughs in immunotherapies for B-cell lymphoid malignancies and multiple myeloma, but progress has been much less for acute myeloid leukemia (AML). Nevertheless, challenge begets innovation and several therapeutic strategies are under investigation.

SUMMARY

In this review, we review the state of the art in AML immunotherapy including CD33- and CD123-targeted agents, immune checkpoint inhibition, and adoptive cell therapy strategies. We also share conceptual frameworks for approaching the growing catalog of investigational AML immunotherapies and propose future directions for the field.

KEY MESSAGES

Immunotherapies for AML face significant challenges but novel strategies are in development.

Recent Prospective in CAR T-Based Therapy for Solid and Hematological Malignancies

Given that CAR-T cell therapy is effective in CD19-positive blood malignancies, it offers great hope for a variety of aggressive tumors that have thus far shown very little response to available therapies [...].