Jonathan C. Lansing

Controlled tetra-Fc sialylation of IVIg results in a drug candidate with consistent enhanced anti-inflammatory activity

Significance IgG fragment crystallizable domain (Fc) sialylation has emerged as an important but controversial concept for regulating anti-inflammatory activity of antibodies. Moreover, translating this concept to potent anti-inflammatory therapeutics has been hampered by the difficulty of generating suitable sialylated products for human use. We describe for the first time, to our knowledge, the development of a robust, scalable process to generate a sialylated intravenous immunoglobulin (IVIg) drug candidate with maximum Fc sialylation devoid of unwanted modifications. By using a wide panel of physicochemical analytics and in vivo models, we have validated the quality and potent anti-inflammatory activity of this clinical candidate. This report not only confirms the controversial anti-inflammatory activity of IgG-Fc sialylation, it also represents the first sialylated IVIg preparation, to our knowledge, with consistent anti-inflammatory potency suitable for clinical development. Despite the beneficial therapeutic effects of intravenous immunoglobulin (IVIg) in inflammatory diseases, consistent therapeutic efficacy and potency remain major limitations for patients and physicians using IVIg. These limitations have stimulated a desire to generate therapeutic alternatives that could leverage the broad mechanisms of action of IVIg while improving therapeutic consistency and potency. The identification of the important anti-inflammatory role of fragment crystallizable domain (Fc) sialylation has presented an opportunity to develop more potent Ig therapies. However, translating this concept to potent anti-inflammatory therapeutics has been hampered by the difficulty of generating suitable sialylated products for clinical use. Therefore, we set out to develop the first, to our knowledge, robust and scalable process for generating a well-qualified sialylated IVIg drug candidate with maximum Fc sialylation devoid of unwanted alterations to the IVIg mixture. Here, we describe a controlled enzymatic, scalable process to produce a tetra-Fc–sialylated (s4-IVIg) IVIg drug candidate and its qualification across a wide panel of analytic assays, including physicochemical, pharmacokinetic, biodistribution, and in vivo animal models of inflammation. Our in vivo characterization of this drug candidate revealed consistent, enhanced anti-inflammatory activity up to 10-fold higher than IVIg across different animal models. To our knowledge, this candidate represents the first s4-IVIg suitable for clinical use; it is also a valuable therapeutic alternative with more consistent and potent anti-inflammatory activity.

Fast and accurate fitting of relaxation dispersion data using the flexible software package GLOVE

Relaxation dispersion spectroscopy is one of the most widely used techniques for the analysis of protein dynamics. To obtain a detailed understanding of the protein function from the view point of dynamics, it is essential to fit relaxation dispersion data accurately. The grid search method is commonly used for relaxation dispersion curve fits, but it does not always find the global minimum that provides the best-fit parameter set. Also, the fitting quality does not always improve with increase of the grid size although the computational time becomes longer. This is because relaxation dispersion curve fitting suffers from a local minimum problem, which is a general problem in non-linear least squares curve fitting. Therefore, in order to fit relaxation dispersion data rapidly and accurately, we developed a new fitting program called GLOVE that minimizes global and local parameters alternately, and incorporates a Monte-Carlo minimization method that enables fitting parameters to pass through local minima with low computational cost. GLOVE also implements a random search method, which sets up initial parameter values randomly within user-defined ranges. We demonstrate here that the combined use of the three methods can find the global minimum more rapidly and more accurately than grid search alone.

Determination of Torsion Angles in Membrane Proteins

Bacteriorhodopsin (bR) harnesses light energy to transport protons across the cell membrane of H. salinarium. Absorption of a photon by the protonated retinal chromophore initiates a cycle in which the chromophore releases a proton to an aspartate on the extracellular side and reprotonates from an aspartic acid on the cytoplasmic side. Vectorial proton transport depends on a switch in accessibility of the chromophore Schiff base nitrogen from the extracellular to cytoplasmic side. Changes in the retinal conformation are expected to be particularly important for understanding the pumping mechanism.