Variable Heavy Chain Domain Derived from a Cell-Penetrating Anti-DNA Monoclonal Antibody for the Intracellular Delivery of Biomolecules

Overcoming limitations and advancing the therapeutic potential of antibody-oligonucleotide conjugates (AOCs): Current status and future perspectives

As cancer incidence rises due to an aging population, the importance of precision medicine continues to grow. Antibody-drug conjugates (ADCs) exemplify targeted therapies by delivering cytotoxic agents to specific antigens. Building on this concept, researchers have developed antibody-oligonucleotide conjugates (AOCs), which combine antibodies with oligonucleotides to regulate gene expression. This review highlights the mechanism of AOCs, emphasizing their unique ability to selectively target and modulate disease-causing proteins. It also explores the components of AOCs and their application in tumor therapy while addressing key challenges such as manufacturing complexities, endosomal escape, and immune response. The article underscores the significance of AOCs in precision oncology and discusses future directions, highlighting their potential in treating cancers driven by genetic mutations and abnormal protein expression.

Antibody-mimetic drug conjugate with efficient internalization activity using anti-HER2 VHH and duocarmycin

Antibody-mimetic drug conjugate (AMDC) is a cancer cell-targeted drug delivery system based on the non-covalent binding of mutated streptavidin and modified biotin, namely Cupid and Psyche. However, the development of AMDCs is hampered by difficulties in post-translational modification or poor internalization activity. Here, we report an expression, refolding, and purification method for AMDC using a variable heavy chain of heavy chain-only antibodies (VHHs). Monomeric anti-HER2 VHH fused to Cupid was expressed in Escherichia coli inclusion bodies. Solubilization and refolding at optimized reducing conditions and pH levels were selected to form a functional, tetrameric protein (anti-HER2 VHH-Cupid) that can be easily purified based on molecular weight. Anti-HER2 VHH-Cupid non-covalently creates a tight complex with Psyche linked to a potent DNA-alkylating agent, duocarmycin. This complex can be absorbed by the HER2-expressing human breast cancer cell line, KPL-4, and kills KPL-4 cells in vitro and in vivo. The production of a targeting protein with internalizing activity, combined with the non-covalent conjugation of a highly potent payload, renders AMDC a promising platform for developing cancer-targeted therapy.

Biochemistry, structure, and cellular internalization of a four nanobody-bearing Fc dimer

VHH stands for the variable regions of heavy chain only of camelid IgGs. The VHH family forms a set of interesting proteins derived from antibodies that maintain their capacity to recognize the antigen, despite their relatively small molecular weight (in the 12,000 Da range). Continuing our exploration of the possibilities of those molecules, we chose to design alternative molecules with maintained antigen recognition, but enhanced capacity, by fusing four VHH with one Fc, the fragment crystallizable region of antibodies. In doing so, we aimed at having a molecule with superior quantitative antigen recognition (×4) while maintaining its size below the 110 kDa. In the present paper, we described the building of those molecules that we coined VHH₂ -Fc-VHH₂ . The structure of VHH₂ -Fc-VHH₂ in complex with HER2 antigen was determined using electronic microscopy and modeling. The molecule is shown to bind four HER2 proteins at the end of its flexible arms. VHH₂ -Fc-VHH₂ also shows an internalization capacity via HER2 receptor superior to the reference anti-HER2 monoclonal antibody, Herceptin®, and to a simple fusion of two VHH with one Fc (VHH₂ -Fc). This new type of molecules, VHH₂ -Fc-VHH₂ , could be an interesting addition to the therapeutic arsenal with multiple applications, from diagnostic to therapy.

Harnessing SLE Autoantibodies for Intracellular Delivery of Biologic Therapeutics

Intracellular delivery of therapeutic antibodies is highly desirable but remains a challenge for biomedical research and the pharmaceutical industry. Approximately two-thirds of disease-associated targets are found inside the cell. Difficulty blocking these targets with available drugs creates a need for technology to deliver highly specific therapeutic antibodies intracellularly. Historically, antibodies have not been believed to traverse the cell membrane and neutralize intracellular targets. Emerging evidence has revealed that anti-DNA autoantibodies found in systemic lupus erythematosus (SLE) patients can penetrate inside the cell. Harnessing this technology has the potential to accelerate the development of drugs against intracellular targets. Here, we dissect the mechanisms of the intracellular localization of SLE antibodies and discuss how to apply these insights to engineer successful cell-penetrating antibody drugs.