Enzymatic non-covalent synthesis of supramolecular assemblies as a general platform for bioorthogonal prodrugs activation to combat drug resistance

A tumor heterogeneity-independent antigen-responsive nanocarrier enabled by bioorthogonal pre-targeting and click-activated self-immolative polymer

Bioorthogonal pre-targeting alleviate the limitations of traditional nanomedicines in passive and active targeting delivery. However, the high selectivity of bioorthogonal pre-targeting depends on the high expression level of antigens in lesion sites, and there are very limited targets with sufficient overexpression. Herein, we propose a tumor heterogeneity-independent antigen-responsive nanocarrier utilizing bioorthogonal pre-targeting and click-activated self-immolative polymers for stimulus signal conversion and amplification. This approach comprises a tetrazine (Tz) conjugated with trastuzumab (T-Tz), and a bioorthogonally activatable nanocarrier CONP which self-assembled by isocyanide and polyethylene glycol-modified poly (thiocarbamate) (NC-PTC-PEG) and hydrogen sulfide (H2S)-responsive self-immolative polymers. In practice, T-Tz is first injected to actively pretarget HER2-positive tumor cells and followed by the second injection of nanocarrier CONP. The NC-PTC-PEG in CONP undergoes a click reaction with Tz to generate H2S, thereby achieving the transformation from antigen signal to H2S signal. Finally, NO2-PTC-PEG responds to H2S stimulation and undergoes a head-to-tail depolymerization process similar to dominoes to produce a large amount of H2S, further amplifying the stimulus signal. This bioorthogonal pre-targeting combine with click-activated self-immolative polymers is anticipated to enhance the effectiveness of existing pre-targeting strategies for tumor imaging and therapy, with the potential to overcome challenges posed by tumor heterogeneity.

Reactive Oxygen Species-Instructed Supramolecular Assemblies Enable Bioorthogonally Activatable Protein Degradation for Pancreatic Cancer

Proteolysis-Targeting Chimeras (PROTACs) represent a transformative therapeutic platform for targeted protein degradation across diverse disease indications. However, their potent catalytic activity in normal tissues raises significant concerns regarding off-target toxicity. Here, we present a novel supramolecular self-assembly platform for the bioorthogonal control of PROTAC prodrug activation, enabling tumor-specific protein degradation with minimized systemic toxicity. By exploiting the overproduction of reactive oxygen species (ROS) in pancreatic cancer cells, the supramolecular self-assembly approach selectively accumulates bioorthogonal reaction triggers within the targeted malignant cells, which subsequently facilitates the spatiotemporally controlled activation of the bioorthogonally caged PROTAC. This tumor-selective activation mechanism demonstrates enhanced degradation efficiency in pancreatic cancer cells compared to normal cells. In vivo studies reveal potent tumor growth inhibition with complete preservation of major organ histology, confirming the therapeutic index enhancement achieved through a controllable activation strategy. This biomimetic activation platform establishes a generalizable framework for safer PROTAC-based therapies by integrating tumor-specific microenvironmental cues with bioorthogonal reaction engineering.

On-Membrane Supramolecular Assemblies Serving as Bioorthogonal Gating for Melphalan

Covalent drugs have experienced a revival in recent decades due to their advantageous pharmacodynamic profiles and targeting of "undruggable" proteins. However, balancing selectivity, reactivity, and potency is essential for safe and effective drugs. Here, we employ a cell-selective bioorthogonal prodrug design to enhance the selectivity for covalent inhibitors without compromising the reactivity and potency. The upregulation of phosphatase and integrin facilitates the formation of enzyme-instructed supramolecular assemblies (EISA) on the cancer cell membrane. These assemblies localize bioorthogonal reaction handles tetrazine (Tz), which liberate Melphalan from its bioorthogonal prodrug TCO-Mel. The TCO modification disrupts the LAT1-mediated transportation, reducing cellular permeability of TCO-Mel and the corresponding cytotoxicity to normal cells. Although the cell-selective on-membrane assemblies directed prodrug activation restores Melphalan influx to inhibit cancer cell growth. This prodrug activation strategy further demonstrates potent tumor suppression with satisfactory biocompatibility in vivo. Overall, we extend the scope of bioorthogonal prodrug design for covalent drugs via regulating cellular influx of active pharmaceutical ingredients (APIs).

Self-Reporting Ratiometric AIEgen-Peptide Nanoprobes for Activatable Chemotherapy and Noninvasive Imaging of Therapeutic Outcomes

Efficacious chemotherapy and real-time therapeutic monitoring remain major challenges in cancer treatment. Traditional systems often lack tumor specificity, limiting efficacy, and hindering therapy optimization. Moreover, the absence of real-time monitoring can lead to missed opportunities and increased risks of side effects. Herein, we designed a self-reporting ratiometric AIEgen-peptide nanoprobe (TPE-1(Hyd-DOX)-DEVD) for activatable chemotherapy and noninvasive imaging of therapeutic outcomes. When doxorubicin (DOX) in the nanoprobe is selectively activated in the acidic tumor microenvironment, the ensuing caspase-3 cascade triggers a morphological transformation of the nanoprobe that amplifies the TPE fluorescence. This enhancement allows the TPE/DOX fluorescence ratio to serve as an indicator for monitoring DOX activation and for providing therapeutic feedback. Both in vitro and in vivo studies demonstrated that TPE-1(Hyd-DOX)-DEVD exhibited an impressive tumor suppression efficacy and excellent biocompatibility. This study highlights the strong potential of this nanoprobe as a valuable tool for cancer theranostics, offering hope for more effective and personalized treatment strategies.

Toward Realization of Bioorthogonal Chemistry in the Clinic

In the last decade, the use of bioorthogonal chemistry toward medical applications has increased tremendously. Besides being useful for the production of pharmaceuticals, the efficient, nontoxic reactions open possibilities for the development of therapies that rely on in vivo chemistry between two bioorthogonal components. Here we discuss the latest developments in bioorthogonal chemistry, with a focus on their use in living organisms, the translation from model systems to humans, and the challenges encountered during preclinical development. We aim to provide the reader a broad presentation of the current state of the art and demonstrate the numerous possibilities that bioorthogonal reactions have for clinical use, now and in the near future.

Assembling a new generation of radiopharmaceuticals with supramolecular theranostics

Supramolecular chemistry has been used to tackle some of the major challenges in modern science, including cancer therapy and diagnosis. Supramolecular platforms provide synthetic flexibility, rapid generation through self-assembly, facile labelling, unique topologies, tunable reversibility of the enabling noncovalent interactions, and opportunities for host-guest chemistry and mechanical bonding. In this Review, we summarize recent advances in the design and radiopharmaceutical application of discrete self-assembled coordination complexes and mechanically interlocked molecules - namely, metallacages and rotaxanes, respectively - as well as in situ-forming supramolecular aggregates, specifically pinpointing their potential as next-generation radiotheranostic agents. The outlook of such supramolecular constructs for potential applications in the clinic is discussed.

Bioorthogonal chemistry-based prodrug strategies for enhanced biosafety in tumor treatments: current progress and challenges

Cancer is a significant global health challenge, and while chemotherapy remains a widely used treatment, its non-specific toxicity and broad distribution can lead to systemic side effects and limit its effectiveness against tumors. Therefore, the development of safer chemotherapy alternatives is crucial. Prodrugs hold great promise, as they remain inactive until they reach the cancer site, where they are selectively activated by enzymes or specific factors, thereby reducing side effects and improving targeting. However, subtle differences in the microenvironments between tumors and normal tissue may still result in unintended cytotoxicity. Bioorthogonal reactions, known for their selectivity and precision without interfering with natural biochemical processes, are gaining attention. When combined with prodrug strategies, these reactions offer the potential to create highly effective chemotherapy drugs. This review examines the safety and efficacy of prodrug strategies utilizing various bioorthogonal reactions in cancer treatment.

Investigating the therapeutic potential of hesperidin targeting CRISP2 in intervertebral disc degeneration and cancer risk mitigation

Background

Intervertebral disc degeneration (IDD) can lead to disc herniation and spinal instability, sometimes requiring surgical intervention. Currently, estrogen has a potential protective effect on IDD, and estrogen is associated with an increased risk of some cancers, such as breast and endometrial cancer. Therefore, it is important to identify natural compounds that estrogen analogues treat IDD while reducing the risk of tumor development.

Objective

This study aims to explore a natural metabolic treatment strategy by targeting CRISP2 with the natural compound Hesperidin to mimic the protective effects of estrogen on IDD and reduce the risk of tumor development.

Methods

Microarray data from healthy volunteers and IDD patients were extracted from the Gene Expression Omnibus (GEO) database, and RNA sequencing and clinical data from various cancer types were analyzed. Differentially expressed genes (DEGs) were identified using the Bioconductor Limma package, followed by principal component analysis, volcano plot, and heatmap visualization. Additionally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, CIBERSORT and ssGSEA immune cell infiltration assessments, survival analysis, metabolite enrichment analysis, and molecular docking were performed. Hesperidin's interaction with CRISP2 was further validated through molecular docking and experimental studies.

Results

Hesperidin significantly reduced the expression of CRISP2, iNOS, and COX2 in IDD models, decreased reactive oxygen species (ROS) and apoptosis, and diminished inflammatory markers. CIBERSORT and ssGSEA analyses revealed a correlation between CRISP2 and immune cell infiltration. Survival analysis demonstrated that CRISP2 expression levels were associated with patient survival across various cancer types. Hesperidin was found to mimic estrogen's effects on IDD and reduce tumor progression. Cell culture and experimental validation confirmed Hesperidin's protective effects on nucleus pulposus cells (NPCs).

Conclusion

Hesperidin, as a potential natural metabolic regulator, not only has therapeutic effects on IDD but may also synergize with estrogen therapy to promote spinal health without increasing cancer risk. This study presents a new clinical approach for IDD treatment and lays the foundation for further drug development and experimental research.

Intrahippocampal Supramolecular Assemblies Directed Bioorthogonal Liberation of Neurotransmitters to Suppress Seizures in Freely Moving Mice

The precise delivery of anti-seizure medications (ASM) to epileptic loci remains the major challenge to treat epilepsy without causing adverse drug reactions. The unprovoked nature of epileptic seizures raises the additional need to release ASMs in a spatiotemporal controlled manner. Targeting the oxidative stress in epileptic lesions, here the reactive oxygen species (ROS) induced in situ supramolecular assemblies that synergized bioorthogonal reactions to deliver inhibitory neurotransmitter (GABA) on-demand, are developed. Tetrazine-bearing assembly precursors undergo oxidation and selectively self-assemble under pathological conditions inside primary neurons and mice brains. Assemblies induce local accumulation of tetrazine in the hippocampus CA3 region, which allows the subsequent bioorthogonal release of inhibitory neurotransmitters. For induced acute seizures, the sustained release of GABA extends the suppression than the direct supply of GABA. In the model of permanent damage of CA3, bioorthogonal ligation on assemblies provides a reservoir of GABA that behaves prompt release upon 365 nm irradiation. Incorporated with the state-of-the-art microelectrode arrays, it is elucidated that the bioorthogonal release of GABA shifts the neuron spike waveforms to suppress seizures at the single-neuron precision. The strategy of in situ supramolecular assemblies-directed bioorthogonal prodrug activation shall be promising for the effective delivery of ASMs to treat epilepsy.

Nanofibers in Organelles: From Structure Design to Biomedical Applications

Nanofibers are one of the most important morphologies of molecular self-assemblies, the formation of which relies on the diverse intermolecular interactions of fibrous-forming units. In the past decade, rapid advances have been made in the biomedical application of nanofibers, such as bioimaging and tumor treatment. An important topic to be focused on is not only the nanofiber formation mechanism but also where it forms, because different destinations could have different influences on cells and its formation could be triggered by unique stimuli in organelles. It is therefore necessary and timely to summarize the nanofibers assembled in organelles. This minireview discusses the formation mechanism, triggering strategies, and biomedical applications of nanofibers, which may facilitate the rational design of nanofibers, improve our understanding of the relationship between nanofiber properties and organelle characteristics, allow a comprehensive recognition of organelles affected by materials, and enhance the therapeutic efficiency of nanofibers.

A Dual-Mechanism Targeted Bioorthogonal Prodrug Therapy

Bioorthogonal prodrug therapies offer an intriguing two-component system that features enhanced circulating stability and controlled activation on demand. Current strategies often deliver either the prodrug or its complementary activator to the tumor with a monomechanism targeted mechanism, which cannot achieve the desired antitumor efficacy and safety profile. The orchestration of two distinct and orthogonal mechanisms should overcome the hierarchical heterogeneity of solid tumors to improve the delivery efficiency of both components simultaneously for bio-orthogonal prodrug therapies. We herein developed a dual-mechanism targeted bioorthogonal prodrug therapy by integrating two orthogonal, receptor-independent tumor-targeting strategies. We first employed the endogenous albumin transport system to generate the in situ albumin-bound, bioorthogonal-caged doxorubicin prodrug with extended plasma circulation and selective accumulation at the tumor site. We then employed enzyme-instructed self-assembly (EISA) to specifically enrich the bioorthogonal activators within tumor cells. As each targeted delivery mode induced an intrinsic pharmacokinetic profile, further optimization of the administration sequence according to their pharmacokinetics allowed the spatiotemporally controlled prodrug activation on-target and on-demand. Taken together, by orchestrating two discrete and receptor-independent targeting strategies, we developed an all-small-molecule based bioorthogonal prodrug system for dual-mechanism targeted anticancer therapies to maximize therapeutic efficacy and minimize adverse drug reactions for chemotherapeutic agents.

Bioorthogonal chemistry for prodrug activation in vivo

Prodrugs have emerged as a major strategy for addressing clinical challenges by improving drug pharmacokinetics, reducing toxicity, and enhancing treatment efficacy. The emergence of new bioorthogonal chemistry has greatly facilitated the development of prodrug strategies, enabling their activation through chemical and physical stimuli. This "on-demand" activation using bioorthogonal chemistry has revolutionized the research and development of prodrugs. Consequently, prodrug activation has garnered significant attention and emerged as an exciting field of translational research. This review summarizes the latest advancements in prodrug activation by utilizing bioorthogonal chemistry and mainly focuses on the activation of small-molecule prodrugs and antibody-drug conjugates. In addition, this review also discusses the opportunities and challenges of translating these advancements into clinical practice.

Intracellular fluorogenic supramolecular assemblies for self-reporting bioorthogonal prodrug activation

A visual drug delivery system (DDS) is urgently needed for precision medicine. DDS-mediated bioorthogonal prodrug activation strategies have demonstrated remarkable advantages in enlarging a therapeutic index via the alleviation of adverse drug reactions. However, the events of bioorthogonal prodrug activation remain inaccessible. Here, we construct a self-reporting bioorthogonal prodrug activation system using fluorescence emission to interpret prodrug activation events. In designed reactive oxygen species (ROS)-instructed supramolecular assemblies, the bioorthogonal reaction handle of tetrazine carries a dual role as fluorescence quencher and prodrug activator. The subsequent inverse-electron-demand Diels-Alder (IEDDA) reaction simultaneously liberates fluorescence and active drugs, which form a linear relationship. Differentiated by their cellular redox status, ROS-instructed supramolecular assemblies form selectively in both tumor cells and cell spheroids. Upon prodrug treatment, the brightness of fluorescence reflects the liberation of active drugs, which further correlates with the cell survival rate. Therefore, a fluorescence-based visualizable DDS (VDDS) for bioorthogonal prodrug activation is demonstrated, which should be useful to elucidate the multi-step processes in drug delivery and determine prodrug activation efficacy.