Linkage with cathepsin B-sensitive dipeptide promotes the in vitro and in vivo anticancer activity of PEGylated tumor necrosis factor-alpha (TNF-α) against murine fibrosarcoma

Making smart drugs smarter: The importance of linker chemistry in targeted drug delivery

Smart drugs, such as antibody-drug conjugates, for targeted therapy rely on the ability to deliver a warhead to the desired location and to achieve activation at the same site. Thus, designing a smart drug often requires proper linker chemistry for tethering the warhead with a vehicle in such a way that either allows the active drug to retain its potency while being tethered or ensures release and thus activation at the desired location. Recent years have seen much progress in the design of new linker activation strategies. Herein, we review the recent development of chemical strategies used to link the warhead with a delivery vehicle for preferential cleavage at the desired sites.

Antibody-conjugated drug assay for protease-cleavable antibody-drug conjugates

BACKGROUND

Antibody-drug conjugates (ADCs) require multiple assays to characterize their PK. These assays can separately evaluate the ADC by quantifying the antibody or the conjugated drug and may give different answers due to assay measurement differences, heterogeneous nature of ADCs and potential biotransformations that occur in vivo.

RESULTS

We present a new version of the antibody-conjugated drug assay for valine-citrulline-linked monomethylauristatin E (vcMMAE) ADCs. A stable isotope-labeled internal standard, protein A affinity capture and solid-phase cleavage of MMAE using papain was used prior to LC-MS/MS analysis.

CONCLUSION

The assay was used to assess the difference in ex vivo drug-linker stability of native-cysteine versus engineered cysteine ADCs and to determine the number of drugs per antibody of a native-cysteine ADC in vivo.

Trigger responsive polymeric nanocarriers for cancer therapy

Conventional chemotherapy for the treatment of cancer has limited specificity when administered systemically and is often associated with toxicity issues. Enhanced accumulation of polymeric nanocarriers at a tumor site may be achieved by passive and active targeting. Incorporation of trigger responsiveness into these polymeric nanocarriers improves the anticancer efficacy of such systems by modulating the release of the drug according to the tumor environment. Triggers used for tumor targeting include internal triggers such as pH, redox and enzymes and external triggers such as temperature, magnetic field, ultrasound and light. While internal triggers are specific cues of the tumor microenvironment, external triggers are those which are applied externally to control the release. This review highlights the various strategies employed for the preparation of such trigger responsive polymeric nanocarriers for cancer therapy and provides an overview of the state of the art in this field.

Growth factor conjugation: strategies and applications

Growth factors, first known for their essential role in the initiation of mitosis, are required for a variety of cellular processes and their localized delivery is considered as a rational approach in their therapeutic application to assure a safe and effective treatment while avoiding unwanted adverse effects. Noncovalent immobilization of growth factors as well as their covalent conjugation is amongst the most common strategies for localized delivery of growth factors. Today, immobilized and covalently conjugated growth factors are considered as a promising drug design and are widely used for protein reformulation and material design to cover the unwanted characteristics of growth factors as well as improving their functions. Selection of a suitable conjugation technique depends on the substrate chemistry and the availability of functional reactive groups in the structure of growth factor, the position of reactive groups in growth factor molecules and its relation with the receptor binding area, and the intention of creating either patterned or unpatterned conjugation. Various approaches for growth factor reformulation have been reported. This review provides an overview on chemical conjugation of growth factors and covers the relevant studies accomplished for bioconjugation of growth factors and their related application.