The Minimal Effect of Linker Length for Fatty Acid Conjugation to a Small Protein on the Serum Half-Life Extension

The Biosynthesis and Applications of Protein Lipidation

Protein lipidation dramatically affects protein structure, localization, and trafficking via remodeling protein-membrane and protein-protein interactions through hydrophobic lipid moieties. Understanding the biosynthesis of lipidated proteins, whether natural ones or mimetics, is crucial for reconstructing, validating, and studying the molecular mechanisms and biological functions of protein lipidation. In this Perspective, we first provide an overview of the natural enzymatic biosynthetic pathways of protein lipidation in mammalian cells, focusing on the enzymatic machineries and their chemical linkages. We then discuss strategies to biosynthesize protein lipidation in mammalian cells by engineering modification machineries and substrates. Additionally, we explore site-specific protein lipidation biosynthesis in vitro via enzyme-mediated ligations and in vivo primarily through genetic code expansion strategies. We also discuss the use of small molecule tools to modulate the process of protein lipidation biosynthesis. Finally, we provide concluding remarks and discuss future directions for the biosynthesis and applications of protein lipidation.

Recycling reaction and separation for FACylation of loxenatide by trade-off between miscibility and immiscibility of reactants and product in methanol solution

The growing demand and scale of production for fatty acid chain modified (FACylated) polypeptide has sparked the interest in novel production technologies. In this study, a recycling reaction and separation process was proposed and applied to the fatty acid chain modification (FACylation) of loxenatide (LOX), which was based on the difference in solubility between reactants and FACylated product. Especially, the mixed PBS-Methanol (MeOH) solution was designed to meet the demands for FACylation of LOX as well as separation of FACylated LOX and residual modifier. In order to ensure the efficient FACylation, a mixed 10% PBS-90% MeOH (v/v) solution was chosen to provide a good miscibility for two reactants, LOX and N-tetradecylmaleimide (C₁₄-MAL). On the other hand, the immiscibility between reactant (C₁₄-MAL) and FACylated product (N-tetradecyl-Loxenatide (C₁₄-LOX)) could realize the separation of C₁₄-LOX when the MeOH concentration was less than 30% (v/v). Based on this strategy, the recycling reaction and separation process for FACylation of LOX was established by adjusting the MeOH concentration in the mixed solution. The reaction yield and recovery of C₁₄-LOX exceeded 97% and 94%, and the excess reactant C₁₄-MAL could be recycled with a recovery of more than 80%. Furthermore, after purification by reversed-phase chromatography, C₁₄-LOX showed good pharmacokinetic and pharmacodynamic properties in vivo. This study will have great application prospects in industrial production of C₁₄-LOX.

Population pharmacokinetics of the anti-PD-1 antibody camrelizumab in patients with multiple tumor types and model-informed dosing strategy

Camrelizumab, a programmed cell death 1 (PD-1) inhibitor, has been approved for the treatment of patients with relapsed or refractory classical Hodgkin lymphoma, nasopharyngeal cancer and non-small cell lung cancer. The aim of this study was to perform a population pharmacokinetic (PK) analysis of camrelizumab to quantify the impact of patient characteristics and to investigate the appropriateness of a flat dose in the dosing regimen. A total of 3092 camrelizumab concentrations from 133 patients in four clinical trials with advanced melanoma, relapsed or refractory classical Hodgkin lymphoma and other solid tumor types were analyzed using nonlinear mixed effects modeling. The PKs of camrelizumab were properly described using a two-compartment model with parallel linear and nonlinear clearance. Then, covariate model building was conducted using stepwise forward addition and backward elimination. The results showed that baseline albumin had significant effects on linear clearance, while actual body weight affected intercompartmental clearance. However, their impacts were limited, and no dose adjustments were required. The final model was further evaluated by goodness-of-fit plots, bootstrap procedures, and visual predictive checks and showed satisfactory model performance. Moreover, dosing regimens of 200 mg every 2 weeks and 3 mg/kg every 2 weeks provided similar exposure distributions by model-based Monte Carlo simulation. The population analyses demonstrated that patient characteristics have no clinically meaningful impact on the PKs of camrelizumab and present evidence for no advantage of either the flat dose or weight-based dose regimen for most patients with advanced solid tumors.