Chemical remodeling cell surface glycans for immunotargeting of tumor cells

Tetrazine-trans-cyclooctene ligation: Unveiling the chemistry and applications within the human body

Bioorthogonal reactions have revolutionized chemical biology by enabling selective chemical transformations within living organisms and cells. This review comprehensively explores bioorthogonal chemistry, emphasizing inverse-electron-demand Diels-Alder (IEDDA) reactions between tetrazines and strained dienophiles and their crucial role in chemical biology and various applications within the human body. This highly reactive and selective reaction finds diverse applications, including cleaving antibody-drug conjugates, prodrugs, proteins, peptide antigens, and enzyme substrates. The versatility extends to hydrogel chemistry, which is crucial for biomedical applications, yet it faces challenges in achieving precise cellularization. In situ activation of cytotoxic compounds from injectable biopolymer belongs to the click-activated protodrugs against cancer (CAPAC) platform, an innovative approach to tumor-targeted prodrug delivery and activation. The CAPAC platform, relying on click chemistry between trans-cyclooctene (TCO) and tetrazine-modified biopolymers, exhibits modularity across diverse tumor characteristics, presenting a promising approach in anticancer therapeutics. The review highlights the importance of bioorthogonal reactions in developing radiopharmaceuticals for positron emission tomography (PET) imaging and theranostics, offering a promising avenue for diverse therapeutic applications.

Metabolic labelling of cancer cells with glycodendrimers stimulate immune-mediated cytotoxicity

The recruitment of antibody naturally present in human blood stream at the surface of cancer cells have been proved a promising immunotherapeutic strategy to fight cancer. Antibody recruiting molecules (ARMs) combining tumor and antibody binding modules have been developed for this purpose, however the formation of the interacting complex with both antibody and cell is difficult to optimize to stimulate immune-mediated cytotoxicity. To circumvent this limitation, we report herein a more direct approach combining cell metabolism of azido-sugar and bio-orthogonal click chemistry to conjugate at the cell glycocalyx structurally well-defined glycodendrimers as antibody binding module (ABM). We demonstrate that this strategy allows not only the recruitment of natural antibody at the surface of isolated cells or solid tumor models but also activate a cytotoxic response with human serum as unique source of immune effectors.

Bioorthogonal Chemistry and Its Applications

Bioorthogonal chemistry is a set of methods using the chemistry of non-native functional groups to explore and understand biology in living organisms. In this review, we summarize the most common reactions used in bioorthogonal methods, their relative advantages and disadvantages, and their frequency of occurrence in the published literature. We also briefly discuss some of the less common but potentially useful methods. We then analyze the bioorthogonal-related publications in the CAS Content Collection to determine how often different types of biomolecules such as proteins, carbohydrates, glycans, and lipids have been studied using bioorthogonal chemistry. The most prevalent biological and chemical methods for attaching bioorthogonal functional groups to these biomolecules are elaborated. We also analyze the publication volume related to different types of bioorthogonal applications in the CAS Content Collection. The use of bioorthogonal chemistry for imaging, identifying, and characterizing biomolecules and for delivering drugs to treat disease is discussed at length. Bioorthogonal chemistry for the surface attachment of proteins and in the use of modified carbohydrates is briefly noted. Finally, we summarize the state of the art in bioorthogonal chemistry and its current limitations and promise for its future productive use in chemistry and biology.

Engineering Nanoscale Artificial Antigen-Presenting Cells by Metabolic Dendritic Cell Labeling to Potentiate Cancer Immunotherapy

Nanoscale artificial antigen-presenting cells (aAPCs) are promising to activate T cells directly for cancer immunotherapy, while feasible and flexible strategy to develop nanoscale aAPCs remains highly desirable. Metabolic glycoengineering is used to decorate chemical tags on cells which enables bioorthogonal chemical conjugation of functional molecules. Herein, we develop a nanoscale aAPC by metabolic dendritic cell (DC) labeling to mobilize T-cell based antitumor immunity. We coat azido-labeled DC membrane on imiquimod-loaded polymeric nanoparticles and sequentially modify anti-CD3ε antibody via click chemistry. The nanoscale aAPCs perform improved distribution in lymph nodes and stimulate T cells and resident APCs. Significant inhibition of tumor inoculation and growth is observed after the vaccination, which can be further improved by combining antiprogrammed cell death receptor 1 (PD1) therapy. Our results demonstrate the promising application of metabolically labeled DCs for designing nanoscale aAPCs, which provide a simple and general strategy to potentiate cancer immunotherapy.

Metabolic glycan labelling for cancer-targeted therapy

Metabolic glycoengineering with unnatural sugars provides a powerful tool to label cell membranes with chemical tags for subsequent targeted conjugation of molecular cargos via efficient chemistries. This technology has been widely explored for cancer labelling and targeting. However, as this metabolic labelling process can occur in both cancerous and normal cells, cancer-selective labelling needs to be achieved to develop cancer-targeted therapies. Unnatural sugars can be either rationally designed to enable preferential labelling of cancer cells, or specifically delivered to cancerous tissues. In this Review Article, we will discuss the progress to date in design and delivery of unnatural sugars for metabolic labelling of tumour cells and subsequent development of tumour-targeted therapy. Metabolic cell labelling for cancer immunotherapy will also be discussed. Finally, we will provide a perspective on future directions of metabolic labelling of cancer and immune cells for the development of potent, clinically translatable cancer therapies.

Modified endometriosis fertility index is more accurate to predict the non-ART pregnancy rate following surgery: a cohort of Chinese women

OBJECTIVE

To examine whether a modified endometriosis fertility index (EFI) can better predict the rate of pregnancy without assisted reproductive technologies (ART) after laparoscopic surgery in infertile Chinese women with endometriosis.

METHODS

564 infertile women undergoing laparoscopy for endometriosis were retrospectively collected from January 2014 to December 2018. 472 patients were used to modify the EFI based on new, optimal cutoffs for its predictor variables. The predictive accuracy of the modified EFI was examined in the other 92 patients.

RESULTS

Among the patients for the EFI modification, the multivariable Cox regression results showed that historical factors made more contribution in predicting non-ART pregnancy rate than surgical factors both in modified EFI (C-index: historical factors 0.617 vs surgical factors 0.558) and original EFI (C-index: historical factors 0.600 vs surgical factors 0.549). No significant relationship between the prior pregnancy and post-operative non-ART pregnancy rates was detected by both modified EFI and original EFI (p = 0.530 and 0.802, respectively). To assess the predictive effect of modified EFI, the two versions of modified EFI not only had higher predictive accuracy (C-index: 0.627 and 0.632) for non-ART pregnancy rates than that of the original EFI (C-index: 0.602) in the patients undergoing surgery during 2014-2017, but also higher than that of the original EFI (C-index: 0.638 and 0.612 vs 0.560) in the externally validated population in 2018.

CONCLUSIONS

A modified EFI based on population-specific optimal cutoffs and weights might be more suitable for estimating the rate of non-ART pregnancy after laparoscopic surgery in infertile women with endometriosis.

Metabolic labeling and targeted modulation of dendritic cells

Targeted immunomodulation of dendritic cells (DCs) in vivo will enable manipulation of T-cell priming and amplification of anticancer immune responses, but a general strategy has been lacking. Here we show that DCs concentrated by a biomaterial can be metabolically labelled with azido groups in situ, which allows for their subsequent tracking and targeted modulation over time. Azido-labelled DCs were detected in lymph nodes for weeks, and could covalently capture dibenzocyclooctyne (DBCO)-bearing antigens and adjuvants via efficient Click chemistry for improved antigen-specific CD8⁺ T-cell responses and antitumour efficacy. We also show that azido labelling of DCs allowed for in vitro and in vivo conjugation of DBCO-modified cytokines, including DBCO-IL-15/IL-15Rα, to improve priming of antigen-specific CD8⁺ T cells. This DC labelling and targeted modulation technology provides an unprecedented strategy for manipulating DCs and regulating DC-T-cell interactions in vivo.