Ambarish Shah

Formulation Development of Therapeutic Monoclonal Antibodies Using High-Throughput Fluorescence and Static Light Scattering Techniques: Role of Conformational and Colloidal Stability

In this work, we describe the application of two different high-throughput screening (HTS) techniques that can be used to determine protein stability during early formulation development. Differential scanning fluorescence (DSF) and differential static light scattering (DSLS) are used to determine the conformational and colloidal stability of therapeutic monoclonal antibodies (mAbs) during thermal denaturation in a high-throughput fashion. DSF utilizes SYPRO Orange, a polarity-sensitive extrinsic fluorescent probe, to monitor protein unfolding. We found that melting temperatures determined by DSF have a linear correlation with melting temperatures of the first domain unfolding determined by differential scanning calorimetry, establishing DSF as a reliable method for measuring thermal stability. The DSLS method employs static light scattering to evaluate protein stability during thermal denaturation in a 384-well format. Overall comparison between mAb aggregation under typical accelerated stress conditions (40°C) and the thermal stability obtained by DSF and DSLS is also presented. Both of these HTS methods are cost effective with high-throughput capability and can be implemented in any laboratory. Combined with other emerging HTS techniques, DSF and DSLS could be powerful tools for mAb formulation optimization.

Buffer-Dependent Fragmentation of a Humanized Full-Length Monoclonal Antibody

During storage stability studies of a monoclonal antibody (mAb) it was determined that the primary route of degradation involved fragmentation into lower molecular weight species. The fragmentation was characterized with size-exclusion high performance liquid chromatography (SE-HPLC), SDS-PAGE, and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry. Fragmentation proceeded via hydrolysis, likely catalyzed by trace metal ions, of a peptide bond in the hinge region of the mAbs heavy chain, which produced two prominent low molecular weight species during storage: a single, free Fab fragment and a Fab + Fc fragment. The fragmentation is observed in phosphate-buffered solutions at two ionic strengths but not in histidine-buffered solutions at identical ionic strengths. Chaotrope-induced and thermally induced unfolding studies of the mAb indicated differences in the unfolding pathways between the two buffer solutions. The folding intermediate observed during chaotrope-induced unfolding was further characterized by intrinsic fluorescence quenching, which suggested that a small portion of the molecule is resistant to chaotrope-induced unfolding in histidine buffer systems. The thermally induced unfolding indicates a reduction in cooperativity of the unfolding process in the presence of histidine relative to phosphate. A relationship between the histidine-induced effects on unfolding pathway and the relative resistance to fragmentation is suggested.

Plasmonic measurements of monoclonal antibody self‐association using self‐interaction nanoparticle spectroscopy

One of the most significant challenges in developing therapeutic monoclonal antibodies (mAbs) is their unpredictable solubilities and viscosities at the high concentrations required for subcutaneous delivery. This challenge has motivated the development of screening assays that rapidly identify mAb variants with minimal self-association propensities and/or formulation conditions that suppress mAb self-association. Here we report an improved version of self-interaction nanoparticle spectroscopy (SINS)capable of characterizing both repulsive and attractive self-interactions between diverse mAbs. The basis of SINS is that self-interactions between mAbs immobilized on gold nanoparticles increase (repulsion) or decrease (attraction)interparticle distances, which shift the wavelength of maximum absorbance (plasmon wavelength) in opposite directions.We find that the robustness of SINS is improved by varying the amount of immobilized mAb by co-adsorbing a polyclonal antibody. The slopes of the plasmon wavelength shifts as a function of the amount of immobilized mAb (0.01–0.1 mg/mL) are correlated with diffusion interaction parameters measured at two to three orders of magnitude higher antibody concentrations. The ability of SINS to rapidly screen mAb self-association in a microplate format using dilute mAb solutions makes it well suited for use in diverse settings ranging from antibody discovery to formulation.One of the most significant challenges in developing therapeutic monoclonal antibodies (mAbs) is their unpredictable solubilities and viscosities at the high concentrations required for subcutaneous delivery. This challenge has motivated the development of screening assays that rapidly identify mAb variants with minimal self‐association propensities and/or formulation conditions that suppress mAb self‐association. Here we report an improved version of self‐interaction nanoparticle spectroscopy (SINS) capable of characterizing both repulsive and attractive self‐interactions between diverse mAbs. The basis of SINS is that self‐interactions between mAbs immobilized on gold nanoparticles increase (repulsion) or decrease (attraction) interparticle distances, which shift the wavelength of maximum absorbance (plasmon wavelength) in opposite directions. We find that the robustness of SINS is improved by varying the amount of immobilized mAb by co‐adsorbing a polyclonal antibody. The slopes of the plasmon wavelength shifts as a function of the amount of immobilized mAb (0.01–0.1 mg/mL) are correlated with diffusion interaction parameters measured at two to three orders of magnitude higher antibody concentrations. The ability of SINS to rapidly screen mAb self‐association in a microplate format using dilute mAb solutions makes it well suited for use in diverse settings ranging from antibody discovery to formulation. Biotechnol. Bioeng. 2014;111: 1513–1520.

Application of Biophysics to the Early Developability Assessment of Therapeutic Candidates and Its Application to Enhance Developability Properties

The emerging technologies in protein engineering and the greater demand for next-generation protein therapeutics with enhanced efficacy, safety, reduced immunogenicity, and improved delivery are translating into increased nomination of more extensively engineered, difficult to develop candidates for development. Recent advances in protein structure, stability, and function relationship combined with advances in biophysics are enabling more comprehensive and accurate developability and manufacturability screening during early research stages. This chapter focuses on current and future challenges in developing therapeutic biological drugs and the application of novel biophysical tools to screen and improve potential developability properties. Based on stage-related requirements like predictability, speed, limited material, and resource availability, the suitability and application of various biophysical tools are discussed. Two case studies are provided to demonstrate the value of such an early risk assessment.

Application of QbD Principles for Lyophilized Formulation Development

A molecule that is not stable in solution is usually lyophilized to achieve pharmaceutically acceptable shelf life. However, just removing the solvent (generally water) does not assure stability. The formulation composition as well as the lyophilization process parameters is critical to achieve desired drug product quality attributes . This chapter describes how the elements of Quality by Design (QbD) can be applied to lyophilized formulation development. Lyophilization process design and development is discussed in the subsequent chapter; however, formulation development takes into consideration the impact of process parameters on product quality attributes.