NMR Assessment of Therapeutic Peptides and Proteins: Correlations That Reveal Interactions and Motions.

NMR measurements of rotational and translational diffusion are used to characterize the solution behavior of a wide variety of therapeutic proteins and peptides. The timescales of motions sampled in these experiments reveal complicated intrinsic solution behavior such as flexibility, that is central to function, as well as self-interactions, stress-induced conformational changes and other critical attributes that can be discovery and development liabilities. Trends from proton transverse relaxation (R2 ) and hydrodynamic radius (Rh ) are correlated and used to identify and differentiate intermolecular from intramolecular interactions. In this study, peptide behavior is consistent with complicated multimer self-assembly, while multi-domain protein behavior is dominated by intramolecular interactions. These observations are supplemented by simulations that include effects from slow transient interactions and rapid internal motions. R2 -Rh correlations provide a means to profile protein motions as well as interactions. The approach is completely general and can be applied to therapeutic and target protein characterization.

Discovery and multimerization of cross-reactive single-domain antibodies against SARS-like viruses to enhance potency and address emerging SARS-CoV-2 variants.

Coronaviruses have been the causative agent of three epidemics and pandemics in the past two decades, including the ongoing COVID-19 pandemic. A broadly-neutralizing coronavirus therapeutic is desirable not only to prevent and treat COVID-19, but also to provide protection for high-risk populations against future emergent coronaviruses. As all coronaviruses use spike proteins on the viral surface to enter the host cells, and these spike proteins share sequence and structural homology, we set out to discover cross-reactive biologic agents targeting the spike protein to block viral entry. Through llama immunization campaigns, we have identified single domain antibodies (VHHs) that are cross-reactive against multiple emergent coronaviruses (SARS-CoV, SARS-CoV-2, and MERS). Importantly, a number of these antibodies show sub-nanomolar potency towards all SARS-like viruses including emergent CoV-2 variants. We identified nine distinct epitopes on the spike protein targeted by these VHHs. Further, by engineering VHHs targeting distinct, conserved epitopes into multi-valent formats, we significantly enhanced their neutralization potencies compared to the corresponding VHH cocktails. We believe this approach is ideally suited to address both emerging SARS-CoV-2 variants during the current pandemic as well as potential future pandemics caused by SARS-like coronaviruses.

Hexamerization of Anti-SARS CoV IgG1 Antibodies Improves Neutralization Capacity.

The SARS-CoV-2 pandemic and particularly the emerging variants have deepened the need for widely available therapeutic options. We have demonstrated that hexamer-enhancing mutations in the Fc region of anti-SARS-CoV IgG antibodies lead to a noticeable improvement in IC50 in both pseudo and live virus neutralization assay compared to parental molecules. We also show that hexamer-enhancing mutants improve C1q binding to target surface. To our knowledge, this is the first time this format has been explored for application in viral neutralization and the studies provide proof-of-concept for the use of hexamer-enhanced IgG1 molecules as potential anti-viral therapeutics.

Development of a novel capillary electrophoresis-based approach for detection of anti-drug antibody responses.

Peggy Sue is a capillary-based western/immunoassay platform that can separate and characterize proteins by size or charge. A quick and automated immunogenicity assay was developed on Peggy Sue based on charge separation and compared with a traditional bridging method using preclinical samples from non-human primate studies. The results generated with the Peggy Sue assay were comparable to those of the bridging assays. The Peggy Sue platform has several advantages, including time efficiency, low sample consumption, and easy automation. The platform is especially ideal for further characterization of anti-drug antibody (ADA) specificity against complex biologics such as bispecific or multi-specific biotherapeutics as it is easy to conduct domain specificity assessment of observed ADA responses. Our evaluation suggests that the Peggy Sue platform is a promising tool for preclinical ADA analysis.

Hyphenation of strong cation exchange chromatography to native mass spectrometry for high throughput online characterization of charge heterogeneity of therapeutic monoclonal antibodies.

Characterization of charge heterogeneity in monoclonal antibodies (mAbs) is needed during developability assessment and downstream development of drug candidates. Charge heterogeneity can come from post-translational modifications like deamidation, isomerization, and sialylation. Elucidation of charge variants with mass spectrometry (MS) has historically been challenging. Due to the nonvolatility and high ionic strength of conventional buffer systems, labor-intensive offline fractionation followed by MS analysis is routinely used. Here, we describe an alternative strategy that directly couples strong cation exchange (SCX) chromatography to high-resolution Orbitrap MS for online native MS analysis (SCX-MS). A combined pH and salt gradient was used for universal separation of mAbs from a wide range of pI values (6.38 ~ 9.2), including infliximab (Remicade®, chimeric IgG1/kappa), NISTmab (humanized IgG1/kappa) and trastuzumab (Herceptin®, humanized IgG1/kappa), without tailoring of chromatographic profiles. Liquid chromatography and MS parameters were optimized to achieve high-quality spectra and enhanced detection of low abundant species under high flow rate conditions. Genedata Expressionist, a vendor agnostic software, was used for data processing. This integrated strategy allows unbiased characterization of numerous charge variant species and low molecular weight fragments (<0.05%) without post-column flow splitting. The application was further expanded with middle-up approaches for subdomain analysis, which demonstrated the versatility of the strategy for analysis of various construct types. With our analysis of mAbs during developability assessment and forced degradation studies, which aimed at assessing potential critical quality attributes in antibody drug molecules, we provide, for the first time, direct visualization of molecular alterations of mAbs at intact level. Furthermore, strong correlation was observed between this novel MS approach and analysis by capillary isoelectric focusing.

Predicting Antibody Developability Profiles Through Early Stage Discovery Screening.

Monoclonal antibodies play an increasingly important role for the development of new drugs across multiple therapy areas. The term 'developability' encompasses the feasibility of molecules to successfully progress from discovery to development via evaluation of their physicochemical properties. These properties include the tendency for self-interaction and aggregation, thermal stability, colloidal stability, and optimization of their properties through sequence engineering. Selection of the best antibody molecule based on biological function, efficacy, safety, and developability allows for a streamlined and successful CMC phase. An efficient and practical high-throughput developability workflow (100 s-1,000 s of molecules) implemented during early antibody generation and screening is crucial to select the best lead candidates. This involves careful assessment of critical developability parameters, combined with binding affinity and biological properties evaluation using small amounts of purified material (<1 mg), as well as an efficient data management and database system. Herein, a panel of 152 various human or humanized monoclonal antibodies was analyzed in biophysical property assays. Correlations between assays for different sets of properties were established. We demonstrated in two case studies that physicochemical properties and key assay endpoints correlate with key downstream process parameters. The workflow allows the elimination of antibodies with suboptimal properties and a rank ordering of molecules for further evaluation early in the candidate selection process. This enables any further engineering for problematic sequence attributes without affecting program timelines.

C17 prevents inflammatory arthritis and associated joint destruction in mice.

C17 was first described about ten years ago as a gene expressed in CD34+ cells. A more recent study has suggested a role for C17 in chondrogenesis and development of cartilage. However, based on sequence analysis, we believe that C17 has homology to IL-2 and hence we present the hypothesis that C17 is a cytokine possessing immune-regulatory properties. We provide evidence that C17 is a secreted protein preferentially expressed in chondrocytes, hence in cartilage-rich tissues. Systemic expression of C17 in vivo reduces disease in a collagen antibody-induced arthritis model in mice (CAIA). Joint protection is evident by delayed disease onset, minimal edema, bone protection and absence of diverse histological features of disease. Expression of genes typically associated with acute joint inflammation and erosion of cartilage or bone is blunted in the presence of C17. Consistent with the observed reduction in bone erosion, we demonstrate reduced levels of RANKL in the paws and sera of mice over-expressing C17. Administration of C17 at the peak of disease, however, had no effect on disease progression, indicating that C17's immune-regulatory activity must be most prominent prior to or at the onset of severe joint inflammation. Based on this data we propose C17 as a cytokine that s contributes to immune homeostasis systemically or in a tissue-specific manner in the joint.