Effects of different conformations of polylysine on the anti-tumor efficacy of methotrexate nanoparticles

TPGS nanoparticles co-loaded with ABT-737 and R848 for breast cancer therapy

The development of new effective drugs to treat breast cancer remains a huge challenge. ABT-737 can inhibit Bcl-2 proteins to promote apoptosis. Resiquimod (R848) is a TLR7/8 agonist that is effective in modulating the immunosuppressive microenvironment. In this study, a codelivery system (TPGS/ABT+R848 NPs) based on D-α-tocopheryl poly (ethylene glycol) 1000 succinate as a potential drug delivery vector to codelivery ABT-737 and R848 was investigated. The size of TPGS/ABT+R848 NPs was 102.5 nm, the drug loading of ABT-737 and R848 was 30.6 % and 12.5 %, and the entrapment efficiency was 84.2 % and 23.7 %, respectively. The nanoparticles showed no significant change in particle size over 14 days. R848 and ABT-737 were released in co-loaded nanoparticles in sequential order. In vitro anti-tumor experiments, the IC50 value of TPGS/ABT+R848 NPs was 0.30 μg·mL-1, 34 times lower than that of free ABT-737. Animal experiments also verified that TPGS/ABT+R848 NPs could enhance the anti-tumor activity, and the tumor weight inhibition rate was 75.3 %. This study demonstrated that TPGS NPs loaded with ABT-737 and R848 have superior combination tumor therapeutic effects, and the co-loaded preparation is conducive to anti-tumor efficacy. The TPGS/ABT+R848 NPs could be a promising platform against breast cancer.

Design and optimization of ε-poly-l-lysine with specific functions for diverse applications

ε-Poly-l-lysine (ε-PL) is a natural homo-poly(amino acid) which can be produced by microorganisms. With the advantages in broad-spectrum antimicrobial activity, biodegradability, and biocompatibility, ε-PL has been widely used as a preservative in the food industry. Different molecular architectures endow ε-PL and ε-PL-based materials with versatile applications. However, the microbial synthesis of ε-PL is currently limited by low efficiencies in genetic engineering and molecular architecture modification. This review presents recent advances in ε-PL production and molecular architecture modification of microbial ε-PL, with a focus on the current challenges and solutions for the improvement of the productivity and diversity of ε-PL. In addition, we highlight recent examples where ε-PL has been applied to expand the versability of edible films and nanoparticles in various applications. Commercial production and the challenges and future research directions in ε-PL biosynthesis are also discussed. Currently, although the main use of ε-PL is as a food preservative, ε-PL and ε-PL-based polymers have shown excellent application potential in biomedical fields. With the development of synthetic biology, the design and synthesis of ε-PL with a customized molecular architecture are possible in the near future. ε-PL-based polymers with specific functions will be a new trend in biopolymer manufacturing.

Glucarpidase (carboxypeptidase G2): Biotechnological production, clinical application as a methotrexate antidote, and placement in targeted cancer therapy

Patients receiving high-dose methotrexate (HDMTX) for malignancies are exposed to diverse complications, including nephrotoxicity, hepatotoxicity, mucositis, myelotoxicity, neurological symptoms, and death. Glucarpidase is a recombinant carboxypeptidase G2 (CPG2) that converts MTX into nontoxic metabolites. In this study, the role of vector type, gene optimization, orientation, and host on the expression of CPG2 is investigated. The effectiveness of various therapeutic regimens containing glucarpidase is classified and perspectives on the dose adjustment based on precision medicine are provided. Conjugation with cell-penetrating peptides, human serum albumin, and polymers such as PEG and dextran for delivery, higher stability, and production of the biobetter variants of CPG2 is highlighted. Conjugation of CPG2 to F(ab՜)2 or scFv antibody fragments against tumor-specific antigens and the corresponding prodrugs for tumor-targeted drug delivery using the antibody-directed enzyme prodrug therapy (ADEPT) is communicated. Trials to reduce the off-target effects and the possibility of repeated ADEPT cycles by adding pro-domains sensitive to tumor-overexpressed proteases, antiCPG2 antibodies, CPG2 mutants with immune-system-unrecognizable epitopes, and protective polymers are reported. Intracellular cpg2 gene expression by gene-directed enzyme prodrug therapy (GDEPT) and the concerns regarding the safety and transfection efficacy of the GDEPT vectors are described. A novel bifunctional platform using engineered CAR-T cell micropharmacies, known as Synthetic Enzyme-Armed KillER (SEAKER) cells, expressing CPG2 to activate prodrugs at the tumor niche is introduced. Taken together, integrated data in this review and recruiting combinatorial strategies in novel drug delivery systems define the future directions of ADEPT, GDEPT, and SEAKER cell therapy and the placement of CPG2 therein.