Evaluation Of mAbs Research Articles

Potent neutralizing human monoclonal antibodies protect from Rift Valley fever encephalitis.

Rift Valley fever (RVF) is an emerging arboviral disease affecting both humans and livestock. In humans, RVF displays a spectrum of clinical manifestations, including encephalitis. To date, there are no FDA-approved vaccines or therapeutics for human use, although several are in preclinical development. Few small-animal models of RVF encephalitis exist, further complicating countermeasure assessment. Human mAbs RVFV-140, RVFV-268, and RVFV-379 are recombinant potently neutralizing antibodies that prevent infection by binding the RVFV surface glycoproteins. Previous studies showed that both RVFV-268 and RVFV-140 improve survival in a lethal mouse model of disease, and RVFV-268 has prevented vertical transmission in a pregnant rat model of infection. Despite these successes, evaluation of mAbs in the context of brain disease has been limited. This is the first study to our knowledge to assess neutralizing antibodies for prevention of RVF neurologic disease using a rat model. Administration of RVFV-140, RVFV-268, or RVFV-379 24 hours prior to aerosol exposure to the virulent ZH501 strain of RVFV resulted in substantially enhanced survival and lack of neurological signs of disease. These results using a stringent and highly lethal aerosol infection model support the potential use of human mAbs to prevent the development of RVF encephalitis.

A framework for the biophysical screening of antibody mutations targeting solvent-accessible hydrophobic and electrostatic patches for enhanced viscosity profiles

The formulation of high-concentration monoclonal antibody (mAb) solutions in low dose volumes for autoinjector devices poses challenges in manufacturability and patient administration due to elevated solution viscosity. Often many therapeutically potent mAbs are discovered, but their commercial development is stalled by unfavourable developability challenges. In this work, we present a systematic experimental framework for the computational screening of molecular descriptors to guide the design of 24 mutants with modified viscosity profiles accompanied by experimental evaluation. Our experimental observations using a model anti-IL8 mAb and eight engineered mutant variants reveal that viscosity reduction is influenced by the location of hydrophobic interactions, while targeting positively charged patches significantly increases viscosity in comparison to wild-type anti-IL-8 mAb. We conclude that most predicted in silico physicochemical properties exhibit poor correlation with measured experimental parameters for antibodies with suboptimal developability characteristics, emphasizing the need for comprehensive case-by-case evaluation of mAbs. This framework combining molecular design and triage via computational predictions with experimental evaluation aids the agile and rational design of mAbs with tailored solution viscosities, ensuring improved manufacturability and patient convenience in self-administration scenarios.

Nonclinical Evaluation of Next-generation Therapeutic Monoclonal Antibodies

Therapeutic monoclonal antibodies (mAbs) exert their effects via binding to specific target molecules, which is expected to show rare off-target adverse reactions. However, nonclinical evaluation of mAbs is difficult because they often lack reactivity toward orthologous targets in animals. During the nonclinical evaluation of mAbs, not only the target molecules but fragment crystallizable (Fc) receptors, which regulate the immune effector functions and pharmacokinetic properties of mAbs, should be considered. In this review, factors for extrapolating nonclinical study results to clinical settings are discussed by focusing on Fc receptors. The human Fcγ receptor family consists of FcγRI, IIa, IIb, IIIa, and IIIb; Fcγ receptors in laboratory animals are structurally and functionally different from those in humans. In addition, interactions between human IgG-Fc, a component of therapeutic mAbs, and animal Fcγ receptors are still not fully understood. With regard to neonatal Fc receptor (FcRn), related molecules comprising the FcRn family are not known; however, critical amino acid residues involved in IgG binding are different between human and mouse. In case of next-generation mAbs with a novel structure or mode of action, knowledge from related drugs is limited. To ensure safety of next-generation mAbs, a thorough understanding of the differences in Fc receptors among species and the interactions between mAbs and Fc receptors is required, and the appropriateness of the nonclinical study design should be carefully examined prior to conducting clinical studies.

Abstract P6-14-17: In Vitro Evaluation of the Anti-EGFR Antibody Cetuximab and the Anti-HER2 Antibody Trastuzumab in a Panel of Human Tumor Cell Lines

Abstract The epidermal growth factor receptors, EGFR (erbB-1) and HER2 (erbB-2), and their down stream signaling events promote tumor growth and survival in a variety of epithelial tumors. Current treatment strategies used to target these receptors include mAbs directed against their extracellular domains and small molecule inhibitors of their tyrosine kinase activities. The efficacy of these types of therapeutics is increasingly being found to be contingent on the genotype of the targeted cancer. In vitro evaluation of mAbs is reliant on selection of tumor cell lines driven by the specific antigen proteins of interest and their associated pathways. We selected a panel of eight human tumor cell lines, six breast cancer (BT474, SK-BR-3, MDA-MB-453, MDA-MB-231, MDA-MB-468 and MCF-7), one colon (SW48) and one skin (A431) with varying levels of HER2, EGFR and EGFR/HER2 expression to evaluate the mAbs cetuximab and trastuzumab for antiproliferative effects, ability to induce apoptosis and the ability to block cell cycle. These findings were compared to results obtained after treatment with lapatinib, erlotinib, Ly294002 and Tamoxifen. The BT474 and SK-BR-3 breast cancer cell lines with HER2 amplified expression demonstrated cytostatic antiproliferative and G1/S cell cycle block sensitivity to the anti-HER2 antibody trastuzumab. The more prominent inhibitory effects observed in the BT474 cell line were further confirmed by measurable induced decreased levels of phospho-Akt and increased levels of the CDK2 inhibitor p27Kip1 following treatment with trastuzumab, lapatinib and Ly294002. The SW48 colon and A431 skin cancer cell lines with EGFR mutations and EGFR over expression, respectively, demonstrated cytostatic antiproliferative sensitivity to the anti-EGFR antibody cetuximab. This in vitro cell-based multiplexed approach for assessment of oncology therapeutics based on genetically directed cell line selection, demarcation of cytostatic and cytotoxic cell proliferation inhibition and assessment of receptor down stream signaling biomarkers offers greater predictive efficacious value and can be used to identify optimal candidates for combination therapies. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-14-17.