Challenges and interventions of chimeric antigen receptor-T cell therapy in solid tumors

[Preparation of Trop2-Targeted CAR-T Cells Based on Nanobodies and Their Antitumor Effects Against Non-Small Cell Lung Cancer]

Objective

To investigate whether chimeric antigen receptor (CAR) T cells constructed with nanobodies based on trophoblast cell-surface antigen 2 (Trop2) can be used to treat Trop2-positive non-small cell lung cancer.

Methods

A Trop2-specific phage display nanobody library was constructed to screen for Trop2-specific nanobodies. The antigen-binding capacities of three Trop2 nanobodies (8#, 14#, and 48#) were assessed using indirect enzyme-linked immunosorbent assay (ELISA), and their binding affinities were analyzed through surface plasmon resonance (SPR) analysis. CAR-T cells were constructed with Trop2-specific nanobodies and were then co-cultured with the Trop2-positive NCI-H292 cell line expressing luciferase and the Trop2-negative A549 cell line. Luciferase values at effector-to-target ratios of 4∶1, 2∶1, 1∶1, and 1∶2 were measured using a multifunctional microplate reader to assess the killing efficiency. The levels of interleukin (IL)-2, interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α) cytokines in the supernatant at an effector-to-target ratio of 4∶1 were measured using the ELISA method. We also established in this study an NCI-H292 xenograft model in NCG immunodeficient mice, which were divided into three groups, a phosphate-buffered saline (PBS) control group, a Mock-T group, and a Trop2 CAR-T group (n = 5). A total of 1×107 Trop2 CAR-T cells were administered via tail vein injection. Throughout the experimental period, the growth and survival status of the mice were observed daily, and tumor sizes were measured once every three days to analyze the survival time.

Results

A Trop2-specific nanobody was successfully screened from the nanobody library, and indirect ELISA initially indicated that nanobody 48# had the strongest affinity. Subsequently, surface plasmon resonance analysis revealed that nanobody 48# exhibited an affinity in the range of 2.49×10－8 M, indicating that it was a high-affinity antibody. Based on this nanobody, Trop2 CAR-T cells were successfully constructed. Furthermore, in vitro experiments demonstrated that Trop2 CAR-T cells killed Trop2-positive NCI-H292 non-small cell lung cancer cells in a dose-dependent manner. ELISA showed a significant increase in the secretion of cytokines (IL-2, IFN-γ, and TNF-α) in the co-culture system, further validating their antitumor activity. In the NCI-H292 xenograft mouse model, the Trop2 CAR-T group exhibited reduced tumor size (P < 0.001) and prolonged survival time of tumor-bearing mice (P < 0.05) compared to the PBS and Mock-T groups.

Conclusion

These findings demonstrate that CAR T cells constructed with Trop2 nanobodies can effectively treat Trop2-positive non-small cell lung cancer.

Revolutionizing Immunotherapy: Unveiling New Horizons, Confronting Challenges, and Navigating Therapeutic Frontiers in CAR-T Cell-Based Gene Therapies

The CAR-T cell therapy has marked the dawn of new era in the cancer therapeutics and cell engineering techniques. The review emphasizes on the challenges that obstruct the therapeutic efficiency caused by cell toxicities, immunosuppressive tumor environment, and decreased T cell infiltration. In the interest of achieving the overall survival (OS) and event-free survival (EFS) of patients, the conceptual background of potential target selection and various CAR-T cell design techniques are described which can minimize the off-target effects, reduce toxicity, and thus increase the resilience of CAR-T cell treatment in the haematological malignancies as well as in solid tumors. Furthermore, it delves into cutting-edge technologies like gene editing and synthetic biology, providing new opportunities to enhance the functionality of CAR-T cells and overcome mechanisms of immune evasion. This review provides a comprehensive understanding of the complex and diverse aspects of CAR-T cell-based gene treatments, including both scientific and clinical aspects. By effectively addressing the obstacles and utilizing the capabilities of cutting-edge technology, CAR-T cell therapy shows potential in fundamentally changing immunotherapy and reshaping the approach to cancer treatment.

Targeting metabolism to improve CAR-T cells therapeutic efficacy

Chimeric antigen receptor T (CAR-T) cell therapy achieved advanced progress in the treatment of hematological tumors. However, the application of CAR-T cell therapy for solid tumors still faces many challenges. Competition with tumor cells for metabolic resources in an already nutrient-poor tumor microenvironment is a major contributing cause to CAR-T cell therapy's low effectiveness. Abnormal metabolic processes are now acknowledged to shape the tumor microenvironment, which is characterized by increased interstitial fluid pressure, low pH level, hypoxia, accumulation of immunosuppressive metabolites, and mitochondrial dysfunction. These factors are important contributors to restriction of T cell proliferation, cytokine release, and suppression of tumor cell-killing ability. This review provides an overview of how different metabolites regulate T cell activity, analyzes the current dilemmas, and proposes key strategies to reestablish the CAR-T cell therapy's effectiveness through targeting metabolism, with the aim of providing new strategies to surmount the obstacle in the way of solid tumor CAR-T cell treatment.