Globally accessible preventive and therapeutic molecules against SARS-CoV-2 are urgently needed. DARPin molecules are an emerging class of novel therapeutics based on naturally occurring repeat proteins (∼15 kDa in size) and can be rapidly produced in bacteria in large quantities. Here, we report the identification of 380 DARPin molecules specifically targeting the SARS-CoV-2 spike protein selected from a naïve library of 1012 DARPin molecules. Using extensive biophysical and biochemical characterization, (pseudo)virus neutralization assays and cryo-EM analysis, 11 mono-DARPin molecules targeting either the receptor binding domain (RBD), the S1 N-terminal-domain (NTD) or the S2 domain of the SARS-CoV-2 spike protein were chosen. Based on these 11 mono-DARPin molecules, 31 anti-SARS-CoV-2 multi-DARPin molecules were constructed which can broadly be grouped into 2 types; multi-paratopic RBD-neutralizing DARPin molecules and multi-mode DARPin molecules targeting simultaneously RBD, NTD and the S2 domain. Each of these multi-DARPin molecules acts by binding with 3 DARPin modules to the SARS-CoV-2 spike protein, leading to potent inhibition of SARS-CoV-2 infection down to 1 ng/ml (12 pM) and potentially providing protection against viral escape mutations. Additionally, 2 DARPin modules binding serum albumin, conferring an expected half-life of about 3 weeks in humans, were included in the multi-DARPin molecules. The protective efficacy of one multi-DARPin molecule was studied in a Golden Syrian hamster SARS-CoV-2 infection model, resulting in a significant reduction in viral load and pathogenesis. In conclusion, the multi-DARPin molecules reported here display very high antiviral potency, high-production yield, and a long systemic half-life, and thereby have the potential for single-dose use for prevention and treatment of COVID-19.

Maytansinoids, the potent cytotoxic derivatives of the alkaloid maytansine are used as payloads in antibody maytansinoid conjugates. This article reviews clinical and preclinical hepatotoxicity observed with antibody maytansinoid conjugates used to treat cancer. Specific aspects of drug distribution, metabolism and excretion that may impact hepatotoxicity are reviewed vis-à-vis the kind of maytansinoid in the conjugate, cleavable or non-cleavable linkers, linker-payload combinations, drug to antibody ratio, metabolite formation, hepatic enzyme induction in relation to drug-drug interactions and species, age and gender differences. The article also sheds light on factors that may protect the liver from toxic insults.

(2015) Integrated pharmacokinetic, pharmacodynamic and immunogenicity profiling of an anti-CCL21 monoclonal antibody in cynomolgus monkeys, mAbs, 7:5, 829-837, DOI: 10.1080DOI: 10. /19420862.2015 To link to this article: https://doi.org/10. 1080/19420862.2015 Keywords: biotherapeutics, chemokine, FIH predictions, mAb, pharmacokinetics, PK/PD model, preclinicalAbbreviations: ADME, absorption, distribution, metabolism, and elimination; ABC, ammonium bicarbonate; ACN, acetonitrile; ADA, anti-drug antibodies; AUC, area under the curve; BSA, bovine serum albumin; CCL, chemokine (C-C) ligand; CCR7, C-C chemokine receptor 7; DOC, sodium deoxycholate; DRF, dose range finding; ELISA, enzyme-linked immunosorbent assay; FA, formic acid; FcRn, neonatal Fc receptor; FFPE, formalin fixed paraffin embedded; HRP, horseradish peroxidase; IAA, iodoacetamide; Ig, immunoglobulin; IG, immunogenicity; IHC, immunohistochemistry; IL, interleukin; LC-MS/MS, liquid chromatography-mass spectrometry/mass spectrometry; LLOQ, lower limit of quantification; MRD, minimal required dilution; PBS, phosphate buffered saline; PD, pharmacodynamic; PK, pharmacokinetic; QC, quality control; RT, room temperature; SIL-IS, stable isotope labeled peptide -internal standard; TCEP, triphosphine hydrochloride; TMB, 3,3 0 ,5,5 0 -tetramethylbenzidine; ULOQ, upper limit of quantification; VH, variable heavy chain QBP359 is an IgG1 human monoclonal antibody that binds with high affinity to human CCL21, a chemokine hypothesized to play a role in inflammatory disease conditions through activation of resident CCR7-expressing fibroblasts/myofibroblasts. The pharmacokinetics (PK) and pharmacodynamics (PD) of QBP359 in non-human primates were characterized through an integrated approach, combining PK, PD, immunogenicity, immunohistochemistry (IHC) and tissue profiling data from single-and multiple-dose experiments in cynomolgus monkeys. When compared with regular immunoglobulin typical kinetics, faster drug clearance was observed in serum following intravenous administration of 10 mg/kg and 50 mg/kg of QBP359. We have shown by means of PK/PD modeling that clearance of mAb-ligand complex is the most likely explanation for the rapid clearance of QBP359 in cynomolgus monkey. IHC and liquid chromatography mass spectrometry data suggested a high turnover and synthesis rate of CCL21 in tissues. Although lymphoid tissue was expected to accumulate drug due to the high levels of CCL21 present, bioavailability following subcutaneous administration in monkeys was 52%. In human disease states, where CCL21 expression is believed to be expressed at 10-fold higher concentrations compared with cynomolgus monkeys, the PK/PD model of QBP359 and its binding to CCL21 suggested that very large doses requiring frequent administration of mAb would be required to maintain suppression of CCL21 in the clinical setting. This highlights the difficulty in targeting soluble proteins with high synthesis rates.

This chapter reviews a range of molecular pathology‐based techniques that are currently used in preclinical animal studies to assist in answering specific scientific questions related to target biology (expression) and biotherapeutic distribution (including off‐target binding). It also highlights the importance of using a combination of appropriate complementary technologies rather than a single technique. The chapter describes an integrated approach that combines pharmacokinetics (PKs), target expression, concentration, receptor occupancy, pathology, immunogenicity, and other relevant information within the same study to characterize and interpret the absorption, distribution, metabolism, and excretion (ADME) profile of a biotherapeutic. This integrated approach can also serve to maximize the information generated in a single study and can limit the number of animals used. Methods used to determine the biodistribution of a therapeutic protein‐based molecule in treated animals include wholebody autoradiography (WBA) and immunohistochemistry (IHC) using either chromagen or fluorescence‐based detection methods.