Improved pharmacokinetic characteristics and bioactive effects of anticancer enzyme delivery systems

Smart nanocarriers for enzyme-activated prodrug therapy

Exogenous enzyme-activated prodrug therapy (EPT) is a potential cancer treatment strategy that delivers non-human enzymes into or on the surface of the cell and subsequently converts a non-toxic prodrug into an active cytotoxic substance at a specific location and time. The development of several pharmacological pairs based on EPT has been the focus of anticancer research for more than three decades. Numerous of these pharmacological pairs have progressed to clinical trials, and a few have achieved application in specific cancer therapies. The current review highlights the potential of enzyme-activated prodrug therapy as a promising anticancer treatment. Different microbial, plant, or viral enzymes and their corresponding prodrugs that advanced to clinical trials have been listed. Additionally, we discuss new trends in the field of enzyme-activated prodrug nanocarriers, including nanobubbles combined with ultrasound (NB/US), mesoscopic-sized polyion complex vesicles (PICsomes), nanoparticles, and extracellular vesicles (EVs), with special emphasis on smart stimuli-triggered drug release, hybrid nanocarriers, and the main application of nanotechnology in improving prodrugs.

Determination of Pralsetinib in Human Plasma and Cerebrospinal Fluid for Therapeutic Drug Monitoring by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS)

BACKGROUND

Ultra-performance Liquid Chromatography-tandem Mass Spectrometry (UPLC-MS/MS) is widely used for concentration detection of many Tyrosine Kinase Inhibitors (TKIs), including afatinib, crizotinib, and osimertinib. In order to analyze whether pralsetinib takes effect in Rearranged during Transfection (RET)-positive patients with central nervous system metastasis, we aimed to develop a method for the detection of pralsetinib concentrations in human plasma and Cerebrospinal Fluid (CSF) by UPLC-MS/MS.

METHODS

The method was developed using the external standard method, and method validation included precision, accuracy, stability, extraction recovery, and matrix effect. Working solutions were all obtained based on stock solutions of pralsetinib of 1mg/mL. The plasma/CSF samples were precipitated by acetonitrile for protein precipitation and then separated on an ACQUITY UPLC HSS T3 column (2.1×100 mm, 1.8 μm) with a gradient elution using 0.1% formic acid (solution A) and acetonitrile (solution B) as mobile phases at a flow rate of 0.4 mL/min. The tandem mass spectrometry was performed by a triple quadrupole linear ion trap mass spectrometry system (QTRAPTM 6500+) with an electrospray ion (ESI) source and Analyst 1.7.2 data acquisition system. Data were collected in Multiple Reaction Monitoring (MRM) and positive ionization mode.

RESULTS

A good linear relationship of pralsetinib in both plasma and CSF was successfully established, and the calibration ranges were found to be 1.0-64.0 μg/mL and 50.0ng/mL-12.8 μg/mL for pralsetinib in the plasma and CSF, respectively. Validation was performed, including calibration assessment, selectivity, precision, accuracy, matrix effect, extraction recovery, and stability, and all results have been found to be acceptable. The method has been successfully applied to pralsetinib concentration detection in a clinical sample, and the concentrations have been found to be 475 ng/mL and 61.55 μg/mL in the CSF and plasma, respectively.

CONCLUSION

We have developed a quick and effective method for concentration detection in both plasma and CSF, and it can be applied for drug monitoring in clinical practice. The method can also provide a reference for further optimization.

Novel trends, challenges and new perspectives for enamel repair and regeneration to treat dental defects

Dental enamel is the hardest tissue in the human body, providing external protection for the tooth against masticatory forces, temperature changes and chemical stimuli. Once enamel is damaged/altered by genetic defects, dental caries, trauma, and/or dental wear, it cannot repair itself due to the loss of enamel producing cells following the tooth eruption. The current restorative dental materials are unable to replicate physico-mechanical, esthetic features and crystal structures of the native enamel. Thus, development of alternative approaches to repair and regenerate enamel defects is much needed but remains challenging due to the structural and functional complexities involved. This review paper summarizes the clinical aspects to be taken into consideration for the development of optimal therapeutic approaches to tackle dental enamel defects. It also provides a comprehensive overview of the emerging acellular and cellular approaches proposed for enamel remineralization and regeneration. Acellular approaches aim to artificially synthesize or re-mineralize enamel, whereas cell-based strategies aim to mimic the natural process of enamel development given that epithelial cells can be stimulated to produce enamel postnatally during the adult life. The key issues and current challenges are also discussed here, along with new perspectives for future research to advance the field of regenerative dentistry.

Biomimetic polysaccharide-cloaked lipidic nanovesicles/microassemblies for improving the enzymatic activity and prolonging the action time for hyperuricemia treatment

The improvement and maintenance of enzymatic activities represent major challenges. However, to address these we developed novel biomimetic polysaccharide hyaluronan (Hn)-cloaked lipidic nanovesicles (BHLN) and microassemblies (BHLNM) as enzyme carriers that function by entrapping enzymes in the core or by tethering them to the inner/outer surfaces via covalent interactions. The effectiveness of these enzyme carriers was demonstrated through an evaluation of the enzymatic activity and anti-hyperuricemia bioactivity of urate oxidase (also called uricase, Uase). We showed that Uase was effectively loaded within the BHLN/BHLNM (UHLN/UHLNM) and maintained good enzymatic bioactivity through a range of effects, including isolation from the external environment due to the vesicle-carrying (shielding effect), avoidance of recognition by the reticuloendothelial system due to Hn-cloaking (long-term effect), production of beneficial conformational changes (allosteric effect) due to a favorable internal microenvironment of construction and vesicle loading, and stabilization due to the reversible conjugation of Uase or vesicle and serum albumin (deposit effect). UHLN/UHLNM had significantly increased bioavailability (∼533% and ∼331% compared to Uase) and demonstrated greatly improved efficacy, whereby the time required for UHLN/UHLNM to lower the plasma uric acid concentration to a normal level was much shorter than that for free Uase. The interactions of the therapeutic enzyme (Uase), biomimetic membrane components (Hn and phospholipid), and serum albumin were investigated with a fluorescent probe and computational simulations to help understand the superior properties of UHLN/UHLNM.

Biomimetic Membrane-Structured Nanovesicles Carrying a Supramolecular Enzyme to Cure Lung Cancer

Platforms for enzyme delivery must simultaneously have plasma stability, high catalytic activity, and low/no immunogenicity of the enzyme. Here, we designed a novel biomimetic membrane-structured nanovesicle (BNV) to efficiently carry supramolecular enzymes to meet the above requirements. We complexed l-asparaginase (Aase) with hydroxypropyl-β-cyclodextrin (HPCD) to form a supramolecular amphiphile (AS) by self-assembly via noncovalent reversible interactions. We then used the first synthesized polyethylene glycol (PEG 2 kDa)-decorated hyaluronan (12 kDa) and HPCD to self-assemble a semipermeable biomimetic membrane-structured nanovesicle (BNV) together with AS loading. As compared to native Aase, AS@BNV exhibited superior catalytic activity preservation, improved catalytic activity, better pharmacokinetics in rats, enhanced cytotoxic effects, increased antitumor efficacy, and decreased side effects. The underlying mechanisms, such as the autophagy inhibition action against tumor cells, protein-protein docking of the interaction between Aase-serum albumin, and decreased hepatic enzymatic activity, were investigated. This approach paves the way for new types of powerful biomimetic-, supramolecular-, and nanocarrier-based enzymatic therapies.

Cytomembrane-mimicking nanocarriers with a scaffold consisting of a CD44-targeted endogenous component for effective asparaginase supramolecule delivery

Highly effective and safe delivery of therapeutic enzymes is pivotal to the success of antitumor therapy. Herein, we report on a targeted enzyme delivery system based on cytomembrane-mimicking nanocarriers (CmN) and a supramolecular technique (SmT). Specifically, each CmN had a scaffold that mainly consisted of a CD44-targeted endogenous component conjugated with polyethylene glycol 2000 (HA-g-PEG) that self-assembled with α-cyclodextrin (ACD). The CmN acted as a microbioreactor with an inner hollow space with the capacity to confine the large molecule asparaginase (Asp) in an Asp/ACD-supramolecular complex conjugated to the inner region. The supramolecular Asp loaded into the CmN (A-S-CmN) exhibited superior stability, kinetic properties, catalytic activity and antitumor effects compared to free Asp due to the dual protection of the supramolecular complex and the nanovesicle, the CD44 targeting-homing ability, the prolonged effects of HA-g-PEG, and the favorable inner microenvironment of the constructed supramolecular CmN. The A-S-CmN also showed a decrease in in vivo toxicity and immunogenicity. CmN combined with SmT therapeutics are easy to implement and extend for use in the delivery of various enzymes and for many types of cancer treatment.