Polymeric micelles (PMs) are promising platforms for enhanced tissue targeting of entrapped therapeutic agents. Strategies to circumvent premature release of entrapped drugs include cross-linking of the micellar core as well as covalent attachment of the drug cargo. The chemistry employed to obtain cross-linked micelles needs to be mild to also allow entrapment of fragile molecules, such as certain peptides, proteins, oligonucleotides, and fluorescent dyes. Native chemical ligation (NCL) is a mild bio-orthogonal reaction between a N-terminal cysteine residue and a thioester that proceeds under physiological conditions. Here, we designed a trifunctional cross-linker containing two cysteine residues for the micelle core-cross-linking reaction and an azide residue for ring-strained alkyne conjugation of fluorescent dyes. We applied this approach to thermosensitive methoxypolyethylene glycol-b-N-(2-hydroxypropyl)methacrylamide-lactate (mPEG-b-HPMAmLac n ) based block copolymers of a core-cross-linked polymeric micelle (CCPM) system by attaching thioester residues (using ethyl thioglycolate-succinic anhydride, ETSA) for NCL cross-linking with the trifunctional cross-linker under physiological conditions. By use of mild copper-free click chemistry, we coupled fluorescent dyes, Sulfo.Cy5 and BODIPY, to the core via the azide residue present on the cross-linker by triazole ring formation. In addition, we employed a recently developed cycloheptyne strain promoted click reagent (TMTHSI, CliCr) in comparison to the frequently employed cyclooctyne derivative (DBCO), both achieving successful dye entrapment. The size of the resulting CCPMs could be tuned between 50 and 100 nm by varying the molecular weight of the thermosensitive block and ETSA content. In vitro cell experiments showed successful internalization of the dye entrapped CCPMs, which did not affect cell viability up to a polymer concentration of 2 mg/mL in PC3 cells. These fluorescent dye entrapped CCPMs can be applied in diagnostic imaging and the chemistry developed in this study serves as a steppingstone toward covalently entrapped fragile drug compounds with tunable release in CCPMs.

Therapy resistance to single agents has led to the realization that combination therapies could become the cornerstone of cancer treatment. To operationalize the selection of effective and safe multitarget therapies, we propose to integrate chemical and preclinical therapeutic information with clinical efficacy and toxicity data, allowing a new perspective on the drug target landscape. To assess the feasibility of this approach, we evaluated the publicly available chemical, preclinical, and clinical therapeutic data, and we addressed some potential limitations while integrating the data. First, by mapping available structured data from the main biomedical resources, we noticed that there is only a 1.7% overlap between drugs in chemical, preclinical, or clinical databases. Especially, the limited amount of structured data in the clinical domain hinders linking drugs to clinical aspects such as efficacy and side effects. Second, to overcome the abovementioned knowledge gap between the chemical, preclinical, and clinical domain, we suggest information extraction from scientific literature and other unstructured resources through natural language processing models, where BioBERT and PubMedBERT are the current state-of-the-art approaches. Finally, we propose that knowledge graphs can be used to link structured data, scientific literature, and electronic health records, to come to meaningful interpretations. Together, we expect this richer knowledge will lower barriers toward clinical application of personalized combination therapies with high efficacy and limited adverse events.