Development and validation of analytical methodologies for the quantification of PCK3145 and PEG-PCK3145 in mice

Intact quantitation and evaluation of a PEG-glycosulfopeptide as a therapeutic P-selectin antagonist

Peptide-based therapeutics are recognized as potent and selective molecules but are often limited by short circulating half-lives, instability towards enzymatic degradation, and immunogenicity. To address these limitations and improve their pharmacological properties, peptides are commonly modified by the covalent attachment of polyethylene glycol (PEG). However, the large molecular weight and polydispersity of PEG chains complicate the interpretation of the full structure of PEGylated peptide therapeutics using standard analytical techniques. Here, we developed a mass spectrometric-based workflow in negative ion mode to identify and quantify GSnP-6, a P-selectin antagonist, with a linear 10 kDa PEG (PEG10) attached at the N-terminus of the glycopeptide. Intact mass analysis with multiple microscans allowed accurate measurements of precursor ions in complex biological mixtures with baseline resolution. Utilizing stepped collision energies improved sequence coverage and enabled identification of key amino acid modifications. We show the utility of this approach in evaluating the properties of PEG10-GSnP-6 in vitro and in vivo. Inhibitory capacity was preserved while extending the half-life of this glycopeptide, as shown by the reduction of P-selectin/PSGL-1 binding. By sustaining effective circulating concentrations, PEG conjugation of a P-selectin glycopeptide antagonist represents a promising therapeutic strategy to target diseases linked to inflammatory processes.

Current status of in vivo bioanalysis of nano drug delivery systems

The development of nano drug delivery systems (NDDSs) provides new approaches to fighting against diseases. The NDDSs are specially designed to serve as carriers for the delivery of active pharmaceutical ingredients (APIs) to their target sites, which would certainly extend the benefit of their unique physicochemical characteristics, such as prolonged circulation time, improved targeting and avoiding of drug-resistance. Despite the remarkable progress achieved over the last three decades, the understanding of the relationships between the in vivo pharmacokinetics of NDDSs and their safety profiles is insufficient. Analysis of NDDSs is far more complicated than the monitoring of small molecular drugs in terms of structure, composition and aggregation state, whereby almost all of the conventional techniques are inadequate for accurate profiling their pharmacokinetic behavior in vivo. Herein, the advanced bioanalysis for tracing the in vivo fate of NDDSs is summarized, including liquid chromatography tandem-mass spectrometry (LC-MS/MS), Förster resonance energy transfer (FRET), aggregation-caused quenching (ACQ) fluorophore, aggregation-induced emission (AIE) fluorophores, enzyme-linked immunosorbent assay (ELISA), magnetic resonance imaging (MRI), radiolabeling, fluorescence spectroscopy, laser ablation inductively coupled plasma MS (LA-ICP-MS), and size-exclusion chromatography (SEC). Based on these technologies, a comprehensive survey of monitoring the dynamic changes of NDDSs in structure, composition and existing form in system (i.e. carrier polymers, released and encapsulated drug) with recent progress is provided. We hope that this review will be helpful in appropriate application methodology for investigating the pharmacokinetics and evaluating the efficacy and safety profiles of NDDSs.