Development of collateral vessels: A new paradigm in CAM angiogenesis model.

The chorioallantoic membrane (CAM) assay is one of the most widely used models to study angiogenesis. In this study, collateral vessel development is reported in CAM assay useful in analysis of angiogenesis. Four days old white Leghorn fertilized chicken eggs were inoculated with vehicle, standard or test angiogenesis inhibitor using standard protocol. Central vessel growth was seen tapering down and collateral vessels were developed from the lower side of the chorioallantoic membrane moving upward in 12 days old standard or test treated CAMs. In the absence of the central vessel, collateral blood supply helped in survival of embryos. Hence, development of collateral vessels was used for ranking of blood vessels and angiogenesis in addition to well-known standard parameters related to central vessel. The finding could differentiate molecules inhibiting angiogenesis with or without collateralization which is crucial in anti-angiogenic therapy used for cardiovascular diseases and cancer. This study proposes a new avenue to distinguish pro-angiogenic molecules from anti-angiogenic ones as well as anti-angiogenic molecules which may or may not support alternative vascularization pathway that would have great impact on future angiogenic and anti-angiogenic therapy.

Current ADC Linker Chemistry.

The list of ADCs in the clinic continues to grow, bolstered by the success of first two marketed ADCs: ADCETRIS® and Kadcyla®. Currently, there are 40 ADCs in various phases of clinical development. However, only 34 of these have published their structures. Of the 34 disclosed structures, 24 of them use a linkage to the thiol of cysteines on the monoclonal antibody. The remaining 10 candidates utilize chemistry to surface lysines of the antibody. Due to the inherent heterogeneity of conjugation to the multiple lysines or cysteines found in mAbs, significant research efforts are now being directed toward the production of discrete, homogeneous ADC products, via site-specific conjugation. These site-specific conjugations may involve genetic engineering of the mAb to introduce discrete, available cysteines or non-natural amino acids with an orthogonally-reactive functional group handle such as an aldehyde, ketone, azido, or alkynyl tag. These site-specific approaches not only increase the homogeneity of ADCs but also enable novel bio-orthogonal chemistries that utilize reactive moieties other than thiol or amine. This broadens the diversity of linkers that can be utilized which will lead to better linker design in future generations of ADCs.

Development of a Single-Step Antibody-Drug Conjugate Purification Process with Membrane Chromatography.

Membrane chromatography is routinely used to remove host cell proteins, viral particles, and aggregates during antibody downstream processing. The application of membrane chromatography to the field of antibody-drug conjugates (ADCs) has been applied in a limited capacity and in only specialized scenarios. Here, we utilized the characteristics of the membrane adsorbers, Sartobind® S and Phenyl, for aggregate and payload clearance while polishing the ADC in a single chromatographic run. The Sartobind® S membrane was used in the removal of excess payload, while the Sartobind® Phenyl was used to polish the ADC by clearance of unwanted drug-to-antibody ratio (DAR) species and aggregates. The Sartobind® S membrane reproducibly achieved log-fold clearance of free payload with a 10 membrane-volume wash. Application of the Sartobind® Phenyl decreased aggregates and higher DAR species while increasing DAR homogeneity. The Sartobind® S and Phenyl membranes were placed in tandem to simplify the process in a single chromatographic run. With the optimized binding, washing, and elution conditions, the tandem membrane approach was performed in a shorter timescale with minimum solvent consumption and high yield. The application of the tandem membrane chromatography system presents a novel and efficient purification scheme that can be realized during ADC manufacturing.

Microwave-assisted Synthesis of an Important Intermediate of Benazepril.

Rapid and efficient methods for the synthesis of an important intermediate of benazepril ethyl 3-phthalimido-2,3,4,5-tetrahydro-1H-[1]benzazepin-2-one-1-acetate under the influence of microwave irradiation are described. A comparative study of conventional and microwave assisted method is briefly discussed.