Molecular Therapy Oncolytics最新文献

Antigen heterogeneity that results in tumor antigenic escape is one of the major obstacles to successful chimeric antigen receptor (CAR) T cell therapies in solid tumors including glioblastoma multiforme (GBM). To address this issue and improve the efficacy of CAR T cell therapy for GBM, we developed an approach that combines CAR T cells with inhibitor of apoptosis protein (IAP) antagonists, a new class of small molecules that mediate the degradation of IAPs, to treat GBM. Here, we demonstrated that the IAP antagonist birinapant could sensitize GBM cell lines and patient-derived primary GBM organoids to apoptosis induced by CAR T cell-derived cytokines, such as tumor necrosis factor. Therefore, birinapant could enhance CAR T cell-mediated bystander death of antigen-negative GBM cells, thus preventing tumor antigenic escape in antigen-heterogeneous tumor models in vitro and in vivo. In addition, birinapant could promote the activation of NF-κB signaling pathways in antigen-stimulated CAR T cells, and with a birinapant-resistant tumor model we showed that birinapant had no deleterious effect on CAR T cell functions in vitro and in vivo. Overall, we demonstrated the potential of combining the IAP antagonist birinapant with CAR T cells as a novel and feasible approach to overcoming tumor antigen heterogeneity and enhancing CAR T cell therapy for GBM.

The clinical use of anti-EGFR antibody-based cancer therapy has been limited by antibody-EGFR binding in normal tissues, so developing pH-dependent anti-EGFR antibodies that selectively bind with EGFR in tumors-by taking advantage of the acidity of tumor microenvironment relative to normal tissues-may overcome these limitations. Here, we generated pH-dependent anti-EGFR antibodies with cross-species reactivity for human and mouse EGFR, and we demonstrate that pH-dependent antibodies exhibit tumor-selective binding by binding strongly to EGFR under acidic conditions (pH 6.5) but binding weakly under neutral (pH 7.4) conditions. Based on screening a non-immune human antibody library and antibody affinity maturation, we initially generated antibodies with cross-species reactivity for human and mouse EGFR. A structure model was subsequently constructed and interrogated for hotspots affecting pH-dependent binding, which supported development of a cross-reactive pH-dependent anti-EGFR antibody, G532. Compared with its non-pH-dependent antibody variant, G532 exhibits improved tumor selectivity, tumor penetration, and antitumor activity. Thus, beyond showing that pH-dependent anti-EGFR antibodies can overcome multiple limitations with antibody-based cancer therapies targeting EGFR, our study illustrates a structure-guided antibody-antigen binding pH-dependency engineering strategy to enhance antibody tumor selectivity and tumor penetration, which can inform the future development of antibody-based cancer therapies targeting other ubiquitously expressed molecules.

Proteolysis targeting chimera (PROTAC) presents a powerful strategy for targeted protein degradation (TPD). The heterobifunctional PROTAC molecule consists of an E3 ligase ligand covalently linked to a protein of interest (POI) via a linker. PROTAC can induce ubiquitinated proteasomal degradation of proteins by hijacking the ubiquitin-proteasome degradation system (UPS). This technique has the advantages of broad targeting profile, good cell permeability, tissue specificity, high selectivity, oral bioavailability, and controllability. To date, a growing number of PROTACs targeting gastrointestinal cancers have been successfully developed, and, in many cases, their POIs have been validated as clinical drug targets. To the best of our knowledge, 15 PROTACs against various targets are currently tested in clinical trials, and many more are likely to be added in the near future. Therefore, this paper details the mechanism, research progress, and application in clinical trials of PROTACs, and summarizes the research achievements related to PROTACs in gastrointestinal cancers. Finally, we discuss the advantages and potential challenges of PROTAC for cancer treatment.

Sodium iodide symporter (NIS) gene transfer for active accumulation of iodide in tumor cells is a powerful theranostic strategy facilitating both diagnostic and therapeutic application of radioiodide. In glioblastoma (GBM), the blood-brain barrier (BBB) presents an additional delivery barrier for nucleic acid nanoparticles. In the present study, we designed dual-targeted NIS plasmid DNA complexes containing targeting ligands for the transferrin receptor (TfR) and the epidermal growth factor receptor (EGFR), thus providing the potential for active transport across the BBB followed by targeting of tumor cells. In vitro ¹²⁵I transfection studies confirmed TfR- and EGFR-dependent transfection efficiency and NIS-specific iodide uptake of dual-targeted polyplexes. In vivo gene transfer in mice bearing orthotopic U87 GBM xenografts was assessed at 48 h after intravenous polyplex injection by positron emission tomography (PET) imaging using ¹⁸F-labeled tetrafluoroborate (TFB) as tracer. The tumoral ¹⁸F-TFB uptake of mice treated with dual-targeted polyplexes (0.56% ± 0.08% ID/mL) was significantly higher compared with mice treated with EGFR-mono-targeted (0.33% ± 0.03% ID/mL) or TfR-mono-targeted (0.27% ± 0.04% ID/mL) polyplexes. In therapy studies, application of ¹³¹I induced a superior therapeutic effect of the dual-targeted therapy, demonstrated by a significant delay in tumor growth and prolonged survival.

Treatment of many cancers, particularly those that remain difficult to treat or are refractive after standard-of-care therapies, has been challenging with cell-based therapies. Although relatively safe as allogeneic therapies and innately effective against cancers without the need for antigen sensitization, natural killer (NK) cells have necessitated use of genetic manipulation approaches to enhance their specificity, persistence, and homing. Chimeric antigen receptor (CAR) and gene-edited NK cell therapies have emerged as a potent treatment modality, addressing many of the issues that have plagued such gene-based therapies with other cell types. Early examples of engineered NK cell therapies have largely leveraged their activity against hematological malignancies in combination with conventional construct architectures or by editing putative genetic targets of immunosuppression. As the motivation to tackle more complex solid tumors grows, so has the sophistication and emergence of NK-specific constructs and engineering approaches. Multi-CARs, combinations with diverse genome editing technologies, as well as responsive and sensing CARs have appeared in the context of NK cell therapy. Here we discuss engineering approaches for NK cell therapy, the latest developments in the field, and what stands in the way of those promises en route to clinical translation.