improving-crispr-cas9-screens-car-t-cells-refined-method-for-library

Improving CRISPR-Cas9 Screens in CAR T Cells: A Refined Method for Library Preparation

Chimeric antigen receptor (CAR) T cell therapies have demonstrated remarkable efficacy in several hematological malignancies, yet their success has not ...

Cima Universidad de Navarra, IdiSNA

Previous studies have shown that functional systemic immunity is required for the efficacy of PD-1/PD-L1 blockade immunotherapies in cancer. Hence, systemic reprogramming of immunosuppressive dysfunctional myeloid cells could overcome resistance to cancer immunotherapy.

Oleuropein-driven reprogramming of the myeloid cell compartment to sensitise tumours to PD-1/PD-L1 blockade strategies.

Monocytic and granulocytic myeloid-derived suppressor cells together with tumor-infiltrating macrophages constitute the main tumor-infiltrating immunosuppressive myeloid populations. Due to the phenotypic resemblance to conventional myeloid cells, their identification and purification from within the tumors is technically difficult and makes their study a challenge. We differentiated myeloid cells modeling the three main tumor-infiltrating types together with uncommitted macrophages, using ex vivo differentiation methods resembling the tumor microenvironment. The phenotype and proteome of these cells was compared to identify linage-dependent relationships and cancer-specific interactome expression modules. The relationships between monocytic MDSCs and TAMs, monocytic MDSCs and granulocytic MDSCs, and hierarchical relationships of expression networks and transcription factors due to lineage and cancer polarization were mapped. Highly purified immunosuppressive myeloid cell populations that model tumor-infiltrating counterparts were systematically analyzed by quantitative proteomics. Full functional interactome maps have been generated to characterize at high resolution the relationships between the three main myeloid tumor-infiltrating cell types. Our data highlights the biological processes related to each cell type, and uncover novel shared and differential molecular targets. Moreover, the high numbers and fidelity of ex vivo-generated subsets to their natural tumor-shaped counterparts enable their use for validation of new treatments in high-throughput experiments.

A Proteomic Atlas of Lineage and Cancer-Polarized Expression Modules in Myeloid Cells Modeling Immunosuppressive Tumor-Infiltrating Subsets.

Immune checkpoint inhibitors (ICIs) have revolutionized medical practice in oncology since the FDA approval of the first ICI 11 years ago. In light of this, Lymphocyte-Activation Gene 3 (LAG-3) is one of the most important next-generation immune checkpoint molecules, playing a similar role as Programmed cell Death protein 1 (PD-1) and Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4). 19 LAG-3 targeting molecules are being evaluated at 108 clinical trials which are demonstrating positive results, including promising bispecific molecules targeting LAG-3 simultaneously with other ICIs. Recently, a new dual anti-PD-1 (Nivolumab) and anti-LAG-3 (Relatimab) treatment developed by Bristol Myers Squibb (Opdualag), was approved by the Food and Drug Administration (FDA) as the first LAG-3 blocking antibody combination for unresectable or metastatic melanoma. This novel immunotherapy combination more than doubled median progression-free survival (PFS) when compared to nivolumab monotherapy (10.1 months versus 4.6 months). Here, we analyze the large clinical trial responsible for this historical approval (RELATIVITY-047), and discuss the preclinical and clinical developments that led to its jump into clinical practice. We will also summarize results achieved by other LAG-3 targeting molecules with promising anti-tumor activities currently under clinical development in phases I, I/II, II, and III. Opdualag will boost the entry of more LAG-3 targeting molecules into clinical practice, supporting the accumulating evidence highlighting the pivotal role of LAG-3 in cancer.

Cutting-Edge: Preclinical and Clinical Development of the First Approved Lag-3 Inhibitor.

Chimeric antigen receptor (CAR)-T adoptive cell therapy is one of the most promising advanced therapies for the treatment of cancer, with unprecedented outcomes in haematological malignancies. However, it still lacks efficacy in solid tumours, possibly because engineered T cells become inactive within the immunosuppressive tumour microenvironment (TME). In the TME, cells of the myeloid lineage (M) are among the immunosuppressive cell types with the highest tumour infiltration rate. These cells interact with other immune cells, mediating immunosuppression and promoting angiogenesis. Recently, the development of CAR-M cell therapies has been put forward as a new candidate immunotherapy with good efficacy potential. This alternative CAR strategy may increase the efficacy, survival, persistence, and safety of CAR treatments in solid tumours. This remains a critical frontier in cancer research and opens up a new possibility for next-generation personalised medicine to overcome TME resistance. However, the exact mechanisms of action of CAR-M and their effect on the TME remain poorly understood. Here, we summarise the basic, translational, and clinical results of CAR-innate immune cells and CAR-M cell immunotherapies, from their engineering and mechanistic studies to preclinical and clinical development.

Cutting-Edge CAR Engineering: Beyond T Cells.

Immunotherapies based on immune checkpoint blockade have shown remarkable clinical outcomes and durable responses in patients with many tumor types. Nevertheless, these therapies lack efficacy in most cancer patients, even causing severe adverse events in a small subset of patients, such as inflammatory disorders and hyper-progressive disease. To diminish the risk of developing serious toxicities, intratumor delivery of monoclonal antibodies could be a solution. Encouraging results have been shown in both preclinical and clinical studies. Thus, intratumor immunotherapy as a new strategy may retain efficacy while increasing safety. This approach is still an exploratory frontier in cancer research and opens up new possibilities for next-generation personalized medicine. Local intratumor delivery can be achieved through many means, but an attractive approach is the use of gene therapy vectors expressing mAbs inside the tumor mass. Here, we summarize basic, translational, and clinical results of intratumor mAb delivery, together with descriptions of non-viral and viral strategies for mAb delivery in preclinical and clinical development. Currently, this is an expanding research subject that will surely play a key role in the future of oncology.

Leading Edge: Intratumor Delivery of Monoclonal Antibodies for the Treatment of Solid Tumors.

Many cancer patients do not benefit from PD-L1/PD-1 blockade immunotherapies. PD-1 and LAG-3 co-upregulation in T-cells is one of the major mechanisms of resistance by establishing a highly dysfunctional state in T-cells. To identify shared features associated to PD-1/LAG-3 dysfunctionality in human cancers and T-cells, multiomic expression profiles were obtained for all TCGA cancers immune infiltrates. A PD-1/LAG-3 dysfunctional signature was found which regulated immune, metabolic, genetic, and epigenetic pathways, but especially a reinforced negative regulation of the TCR signalosome. These results were validated in T-cell lines with constitutively active PD-1, LAG-3 pathways and their combination. A differential analysis of the proteome of PD-1/LAG-3 T-cells showed a specific enrichment in ubiquitin ligases participating in E3 ubiquitination pathways. PD-1/LAG-3 co-blockade inhibited CBL-B expression, while the use of a bispecific drug in clinical development also repressed C-CBL expression, which reverted T-cell dysfunctionality in lung cancer patients resistant to PD-L1/PD-1 blockade. The combination of CBL-B-specific small molecule inhibitors with anti-PD-1/anti-LAG-3 immunotherapies demonstrated notable therapeutic efficacy in models of lung cancer refractory to immunotherapies, overcoming PD-1/LAG-3 mediated resistance.

PD-1/LAG-3 co-signaling profiling uncovers CBL ubiquitin ligases as key immunotherapy targets.

Chimeric antigen receptor (CAR) T cell therapy has revolutionized treatment for hematological malignancies, yet translating this success to solid tumors remains challenging. Major obstacles include antigen heterogeneity, on-target off-tumor toxicity, limited infiltration and persistence, and the immunosuppressive tumor microenvironment (TME). The present review discusses recent engineering strategies designed to overcome these barriers. Innovations such as affinity-tuned and logic-gated CARs improve specificity and safety, while multi-antigen targeting helps address tumor heterogeneity by avoiding antigen escape. Gene-editing approaches enhance CAR T cell fitness by promoting memory phenotypes, metabolic resilience, and resistance to inhibitory signals imposed by the immunosuppressive TME. Additional modifications improve trafficking, enable extracellular matrix degradation, and reprogram CAR T cells to withstand the hostile conditions of the TME. Together, these advances reflect a growing shift toward rational CAR design and synthetic immunology, with the goal of achieving durable and safe responses in solid tumors. Early clinical trials show promise, and continued translational efforts will be key to unlocking the full therapeutic potential of CAR T cells in this setting.

Article	Year
Oleuropein-driven reprogramming of the myeloid cell compartment to sensitise tumours to PD-1/PD-L1 blockade strategies. British journal of cancer\| PubMed ID: 38195888	2024
A Proteomic Atlas of Lineage and Cancer-Polarized Expression Modules in Myeloid Cells Modeling Immunosuppressive Tumor-Infiltrating Subsets. Journal of personalized medicine\| PubMed ID: 34208043	2021
Cutting-Edge: Preclinical and Clinical Development of the First Approved Lag-3 Inhibitor. Cells\| PubMed ID: 35954196	2022
Cutting-Edge CAR Engineering: Beyond T Cells. Biomedicines\| PubMed ID: 36551788	2022
Leading Edge: Intratumor Delivery of Monoclonal Antibodies for the Treatment of Solid Tumors. International journal of molecular sciences\| PubMed ID: 36768997	2023
PD-1/LAG-3 co-signaling profiling uncovers CBL ubiquitin ligases as key immunotherapy targets. EMBO molecular medicine\| PubMed ID: 39030301	2024
Genetic Engineering in CAR T Cells for Solid Tumors: Current State, Barriers and Future Developments. Human gene therapy\| PubMed ID: 40880317	2025

Maider Garnica

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