New Proline, Alanine, Serine Repeat Sequence for Pharmacokinetic Enhancement of Anti-VEGF Single-Domain Antibody

Recombinant protein polymer-antibody conjugates for applications in nanotechnology and biomedicine

Currently, there are over 100 antibody-based therapeutics on the market for the treatment of various diseases. The increasing importance of antibody treatment is further highlighted by the recent FDA emergency use authorization of certain antibody therapies for COVID-19 treatment. Protein-based materials have gained momentum for antibody delivery due to their biocompatibility, tunable chemistry, monodispersity, and straightforward synthesis and purification. In this review, we discuss progress in engineering the molecular features of protein-based biomaterials, in particular recombinant protein polymers, for introducing novel functionalities and enhancing the delivery properties of antibodies and related binding protein domains.

Crosstalk between MUC1 and VEGF in angiogenesis and metastasis: a review highlighting roles of the MUC1 with an emphasis on metastatic and angiogenic signaling

VEGF and its receptor family (VEGFR) members have unique signaling transduction system that play significant roles in most pathological processes, such as angiogenesis in tumor growth and metastasis. VEGF-VEGFR complex is a highly specific mitogen for endothelial cells and any de-regulation of the angiogenic balance implicates directly in endothelial cell proliferation and migration. Moreover, it has been shown that overexpressing Mucin 1 (MUC1) on the surface of many tumor cells resulting in upregulation of numerous signaling transduction cascades, such as growth and survival signaling pathways related to RTKs, loss of cell-cell and cell-matrix adhesion, and EMT. It promotes gene transcription of pro-angiogenic proteins such as HIF-1α during periods of oxygen scarcity (hypoxia) to enhance tumor growth and angiogenesis stimulation. In contrast, the cytoplasmic domain of MUC1 (MUC1-C) inhibits apoptosis, which in turn, impresses upon cell fate. Besides, it has been established that reduction in VEGF expression level correlated with silencing MUC1-C level indicating the anti-angiogenic effect of MUC1 downregulation. This review enumerates the role of MUC1-C oncoprotein and VEGF in angiogenesis and metastasis and describes several signaling pathways by which MUC1-C would mediate the pro-angiogenic activities of cancer cells.

Designing and Development of a Tandem Bivalent Nanobody against VEGF165

Background:

Inhibition of angiogenesis using monoclonal antibodies is an effective strategy in cancer therapy. However, they could not penetrate sufficiently into solid tumors. Antibody fragments have solved this issue. However, they suffer from short in vivo half-life. In the current study, a tandem bivalent strategy was used to enhance the pharmacokinetic parameters of an anti-VEGF165 nanobody.

Methods:

Homology modeling and MD simulation were used to check the stability of protein. The cDNA was cloned into pHEN6C vector and the expression was investigated in WK6 Escherichia coli (E. coli) cells by SDS-PAGE and western blot. After purification, the size distribution of tandem bivalent nanobody was investigated by dynamic light scattering. Moreover, in vitro antiproliferative activity and pharmacokinetic study were studied in HUVECs and Balb/c mice, respectively.

Results:

RMSD analysis revealed the tandem bivalent nanobody had good structural stability after 50 ns of simulation. A hinge region of llama IgG2 was used to fuse the domains. The expression was induced by 1 mM IPTG at 25°C for overnight. A 30 kDa band in 12% polyacrylamide gel and nitrocellulose paper has confirmed the expression. The protein was successfully purified using metal affinity chromatography. MTT assay revealed there is no significant difference between the antiproliferative activity of tandem bivalent nanobody and the native protein. The hydrodynamic radius and terminal half-life of tandem bivalent nanobody increased approximately 2-fold by multivalency compared to the native protein.

Conclusion:

Our data revealed that the physicochemical as well as in vivo pharmacokinetic parameters of tandem bivalent nanobody was significantly improved.

Challenges and advancements in the pharmacokinetic enhancement of therapeutic proteins

Nowadays, proteins are frequently administered as therapeutic agents in human diseases. However, the main challenge regarding the clinical application of therapeutic proteins is short circulating plasma half-life that leads to more frequent injections for maintaining therapeutic plasma levels, increased therapy costs, immunogenic reactions, and low patient compliance. So, the development of novel strategies to enhance the pharmacokinetic profile of therapeutic proteins has attracted great attention in pharmaceuticals. So far, several techniques, each with their pros and cons, have been developed including chemical bonding to polymers, hyper glycosylation, Fc fusion, human serum albumin fusion, and recombinant PEG mimetics. These techniques mainly classify into three strategies; (i) the endosomal recycling of neonatal Fc receptor which is observed for immunoglobulins and albumin, (ii) decrease in receptor-mediated clearance, and (iii) increase in hydrodynamic radius through chemical and genetic modifications. Recently, novel PEG mimetic peptides like proline/alanine/serine repeat sequences are designed to overcome pitfalls associated with the previous technologies. Biodegradability, lack of or low immunogenicity, product homogeneity, and a simple production process, currently make these polypeptides as the preferred technology for plasma half-life extension of therapeutic proteins. In this review, challenges and pitfalls in the pharmacokinetic enhancement of therapeutic proteins using PEG-mimetic peptides will be discussed in detail.