Specific N-terminal attachment of TMTHSI linkers to native peptides and proteins for strain-promoted azide alkyne cycloaddition

The site specific attachment of the reactive TMTHSI-click handle to the N-terminus of peptides and proteins is described. The resulting molecular constructs can be used in strain-promoted azide alkyne cycloaddition (SPAAC) for reaction with azide containing proteins e.g., antibodies, peptides, nanoparticles, fluorescent dyes, chelators for radioactive isotopes and SPR-chips etc

Mechanistic Study on the Degradation of Hydrolysable Core-Crosslinked Polymeric Micelles

Core-crosslinked polymeric micelles (CCPMs) are an attractive class of nanocarriers for drug delivery. Two crosslinking approaches to form CCPMs exist: either via a low-molecular-weight crosslinking agent to connect homogeneous polymer chains with reactive handles or via cross-reactive handles on polymers to link them to each other (complementary polymers). Previously, CCPMs based on methoxy poly(ethylene glycol)- b-poly[ N-(2-hydroxypropyl) methacrylamide-lactate] (mPEG- b-PHPMAmLac n ) modified with thioesters were crosslinked via native chemical ligation (NCL, a reaction between a cysteine residue and thioester resulting in an amide bond) using a bifunctional cysteine containing crosslinker. These CCPMs are degradable under physiological conditions due to hydrolysis of the ester groups present in the crosslinks. The rapid onset of degradation observed previously, as measured by the light scattering intensity, questions the effectiveness of crosslinking via a bifunctional agent. Particularly due to the possibility of intrachain crosslinks that can occur using such a small crosslinker, we investigated the degradation mechanism of CCPMs generated via both approaches using various analytical techniques. CCPMs based on complementary polymers degraded slower at pH 7.4 and 37 °C than CCPMs with a crosslinker (the half-life of the light scattering intensity was approximately 170 h versus 80 h, respectively). Through comparative analysis of the degradation profiles of the two different CCPMs, we conclude that partially ineffective intrachain crosslinks are likely formed using the small crosslinker, which contributed to more rapid CCPM degradation. Overall, this study shows that the type of crosslinking approach can significantly affect degradation kinetics, and this should be taken into consideration when developing new degradable CCPM platforms

Profiling target engagement and cellular uptake of cRGD-decorated clinical-stage core-crosslinked polymeric micelles

Polymeric micelles are increasingly explored for tumor-targeted drug delivery. CriPec® technology enables the generation of core-crosslinked polymeric micelles (CCPMs) based on thermosensitive (mPEG-b-pHPMAmLacn) block copolymers, with high drug loading capacity, tailorable size, and controlled drug release kinetics. In this study, we decorated clinical-stage CCPM with the αvβ3 integrin-targeted cyclic arginine-glycine-aspartic acid (cRGD) peptide, which is one of the most well-known active targeting ligands evaluated preclinically and clinically. Using a panel of cell lines with different expression levels of the αvβ3 integrin receptor and exploring both static and dynamic incubation conditions, we studied the benefit of decorating CCPM with different densities of cRGD. We show that incubation time and temperature, as well as the expression levels of αvβ3 integrin by target cells, positively influence cRGD-CCPM uptake, as demonstated by immunofluorescence staining and fluorescence microscopy. We demonstrate that even very low decoration densities (i.e., 1 mol % cRGD) result in increased engagement and uptake by target cells as compared to peptide-free control CCPM, and that high cRGD decoration densities do not result in a proportional increase in internalization. In this context, it should be kept in mind that a more extensive presence of targeting ligands on the surface of nanomedicines may affect their pharmacokinetic and biodistribution profile. Thus, we suggest a relatively low cRGD decoration density as most suitable for in vivo application

Core-crosslinked polymeric micelles : Principles, preparation, biomedical applications and clinical translation

Polymeric micelles (PM) are extensively used to improve the delivery of hydrophobic drugs. Many different PM have been designed and evaluated over the years, and some of them have steadily progressed through clinical trials. Increasing evidence suggests, however, that for prolonged circulation times and for efficient EPR-mediated drug targeting to tumors and to sites of inflammation, PM need to be stabilized, to prevent premature disintegration. Core-crosslinking is among the most popular methods to improve the in vivo stability of PM, and a number of core-crosslinked polymeric micelles (CCPM) have demonstrated promising efficacy in animal models. The latter is particularly true for CCPM in which (pro-) drugs are covalently entrapped. This ensures proper drug retention in the micelles during systemic circulation, efficient drug delivery to pathological sites via EPR, and tailorable drug release kinetics at the target site. We here summarize recent advances in the CCPM field, addressing the chemistry involved in preparing them, their in vitro and in vivo performance, potential biomedical applications, and guidelines for efficient clinical translation

Specific N-terminal attachment of TMTHSI linkers to native peptides and proteins for strain-promoted azide alkyne cycloaddition

The site specific attachment of the reactive TMTHSI-click handle to the N-terminus of peptides and proteins is described. The resulting molecular constructs can be used in strain-promoted azide alkyne cycloaddition (SPAAC) for reaction with azide containing proteins e.g., antibodies, peptides, nanoparticles, fluorescent dyes, chelators for radioactive isotopes and SPR-chips etc.The N-terminal specific attachment of the reactive TMTHSI-click handle to peptides and proteins is described followed by strain-promoted cycloaddition with azide containing peptides, proteins, nucleic acids, or other small or large azide compounds

TMTHSI, a superior 7-membered ring alkyne containing reagent for strain-promoted azide-alkyne cycloaddition reactions

We describe the development of TMTH-SulfoxImine (TMTHSI) as a superior click reagent. This reagent combines a great reactivity, with small size and low hydrophobicity and compares outstandingly with existing click reagents. TMTHSI can be conveniently functionalized with a variety of linkers allowing attachment of a diversity of small molecules and (peptide, nucleic acid) biologics

High systemic availability of core-crosslinked polymeric micelles after subcutaneous administration

Covalent entrapment of drug molecules within core-crosslinked polymeric micelles (CCPM) represents an attractive approach to improve their therapeutic index. As an alternative to the most commonly employed intravenous (i.v.) route, subcutaneous (s.c.) administration offers the possibility of self-administration and thereby may reduce healthcare costs. The aim of this work was to assess the pharmacokinetic profile and systemic availability of drug-containing CCPM following s.c. injection. We here derivatised dexamethasone (DMS) with three different linkers, which enabled covalent attachment of this drug to the core of CCPM. The obtained DMS-containing CCPM exhibited varying drug release kinetics in vitro. Remarkably, a single dose of DMS-containing CCPM resulted in high systemic availability of about 30% following s.c. injection into the flank of healthy mice, as evidenced by an AUC between 26–37% relative to the AUC attained following i.v. injection. Although different linkers resulted in moderate variations in pharmacokinetic parameters, the overall pharmacokinetic profiles of these i.v. or s.c. administered nanomedicines were not substantially different. Next to DMS, we covalently attached paclitaxel (PTX) to the core of CCPM. Similarly, a single s.c. dose of PTX-containing CCPM resulted in high systemic availability of about 40% compared to i.v. injection and PTX (entrapped plus released) was detected in the blood for at least 3 days. Importantly, the systemic availability of s.c. administered drug-containing CCPM is substantially higher than that of other nanoformulations as reported in the literature (e.g. 3% in rodents). These results demonstrate that s.c. administration is a promising route to attain high systemic availability of CCPM, enabling a potentially more patient-friendly and cost-effective treatment approach than the i.v. route

Cinova: a phase II study of CPC634 (nanoparticulate docetaxel) in patients with platinum resistant recurrent ovarian cancer

OBJECTIVE: Recurrent platinum-resistant ovarian cancer has a poor prognosis with limited therapeutic options. Sub-therapeutic intra-tumoral drug concentrations may add to therapy resistance. CPC634 (docetaxel entrapped in CriPec nanoparticles) was designed to enhance tumor accumulation of drug with localized drug release at the target site to increase therapeutic efficacy. This study investigated the therapeutic effect of CPC634 in patients with platinum-resistant ovarian cancer. METHODS: According to a Simon 2-stage design trial, the first stage included 13 patients, and 12 patients were enrolled in the second stage. Eligible patients had measurable disease and had progressed ≤6 months after the last platinum-based therapy. Platinum-refractory disease was excluded. In stage 1, the number of previous treatment lines was unlimited; in the second stage, a maximum of two prior lines altogether were allowed. The primary endpoint was the objective response rate by Response Evaluation Criteria in Solid Tumor (RECIST) V1.1. Secondary endpoints included safety, progression-free survival at 6 months, cancer antigen 125 (CA125) response, and disease control rate. RESULTS: The patients' median age was 66 years (range 22-77) and most were International Federation of Gynecology and Obstetrics (FIGO) stage III (56%). The median number of previous treatment lines was 3 (range 3-5) in stage I and 2 (range 1-4) in stage II of the study. None of the patients had an objective response, one patient had a CA125 response (5%), and seven patients had stable disease at first evaluation (35%). Median progression-free survival was 1.4 months in stage 1 and 3.0 months in stage 2. Adverse events (all grades) were mainly gastrointestinal in 24 patients (96%), fatigue in 11 (44%), dyspnea in 10 (40%), and infections in 10 (40%) of patients. Grade 3 or higher adverse events occurred in 14 patients (36%), including gastrointestinal in 4 (16%), anemia in 3 (12%), and febrile neutropenia, fatigue, chronic kidney disease, dehydration, and hypertension each in 1 (4%) patient. The trial was stopped prematurely due to futility. CONCLUSIONS: Treatment with CPC634 was feasible, but without apparent clinical activity in patients with recurrent platinum-resistant ovarian cancer. Side effects were mainly gastrointestinal in 24 (96%) patients, including nausea, vomiting, and decreased appetite, fatigue, anemia, and dyspnea