Depleting plasmacytoid dendritic cells reduces local type I interferon responses and disease activity in patients with cutaneous lupus.

Plasmacytoid dendritic cells (pDCs) not only are specialized in their capacity to secrete large amounts of type I interferon (IFN) but also serve to enable both innate and adaptive immune responses through expression of additional proinflammatory cytokines, chemokines, and costimulatory molecules. Persistent activation of pDCs has been demonstrated in a number of autoimmune diseases. To evaluate the potential benefit of depleting pDCs in autoimmunity, a monoclonal antibody targeting the pDC-specific marker immunoglobulin-like transcript 7 was generated. This antibody, known as VIB7734, which was engineered for enhanced effector function, mediated rapid and potent depletion of pDCs through antibody-dependent cellular cytotoxicity. In cynomolgus monkeys, treatment with VIB7734 reduced pDCs in blood below the lower limit of normal by day 1 after the first dose. In two phase 1 studies in patients with autoimmune diseases, VIB7734 demonstrated an acceptable safety profile, comparable to that of placebo. In individuals with cutaneous lupus, VIB7734 profoundly reduced both circulating and tissue-resident pDCs, with a 97.6% median reduction in skin pDCs at study day 85 in VIB7734-treated participants. Reductions in pDCs in the skin correlated with a decrease in local type I IFN activity as well as improvements in clinical disease activity. Biomarker analysis suggests that responsiveness to pDC depletion therapy may be greater among individuals with high baseline type I IFN activity, supporting a central role for pDCs in type I IFN production in autoimmunity and further development of VIB7734 in IFN-associated diseases.

Safety risk management for low molecular weight process-related impurities in monoclonal antibody therapeutics: Categorization, risk assessment, testing strategy, and process development with leveraging clearance potential.

Process-related impurities (PRIs) derived from manufacturing process should be minimized in final drug product. ICH Q3A provides a regulatory road map for PRIs but excludes biologic drugs like monoclonal antibodies (mAbs) that contain biological PRIs (e.g. host cell proteins and DNA) and low molecular weight (LMW) PRIs (e.g., fermentation media components and downstream chemical reagents). Risks from the former PRIs are typically addressed by routine tests to meet regulatory expectations, while a similar routine-testing strategy is unrealistic and unnecessary for LMW PRIs, and thus a risk-assessment-guided testing strategy is often utilized. In this report, we discuss a safety risk management strategy including categorization, risk assessment, testing strategy, and its integrations with other CMC development activities, as well as downstream clearance potentials. The clearance data from 28 mAbs successfully addressed safety concerns but did not fully reveal the process clearance potentials. Therefore, we carried out studies with 13 commonly seen LMW PRIs in a typical downstream process for mAbs. Generally, Protein A chromatography and cation exchange chromatography operating in bind-and-elute mode showed excellent clearances with greater than 1,000- and 100-fold clearance, respectively. The diafiltration step had better clearance (greater than 100-fold) for the positively and neutrally charged LMW PRIs than for the negatively charged or hydrophobic PRIs. We propose that a typical mAb downstream process provides an overall clearance of 5,000-fold. Additionally, the determined sieving coefficients will facilitate diafiltration process development. This report helps establish effective safety risk management and downstream process design with robust clearance for LMW PRIs.

The enhanced immunopharmacology of VIB4920, a novel Tn3 fusion protein and CD40L antagonist, and assessment of its safety profile in cynomolgus monkeys.

BACKGROUND AND PURPOSE: Inhibition of the T- and B-cell interaction through the CD40/CD40 ligand (L) axis is a favourable approach for inflammatory disease treatment. Clinical studies of anti-CD40L molecules in autoimmune diseases have met challenges because of thromboembolic events and adverse haemostasis. VIB4920 (formerly MEDI4920) is a novel CD40L antagonist and Tn3 fusion protein designed to prevent adverse haemostasis and immunopharmacology. We evaluated the pharmacokinetics, activity and toxicity of VIB4920 in monkeys. EXPERIMENTAL APPROACH: Cynomolgus monkeys received i.v. or s.c. 5-300 mg·kg-1 VIB4920 or vehicle, once weekly for 1 month (Studies 1 and 2) or 28 weeks (Study 3). VIB4920 exposure and bioavailability were determined using pharmacokinetic analyses, and immune cell population changes via flow cytometry. Pharmacological activity was evaluated by measuring the animals' capacity to elicit an immune response to keyhole limpet haemocyanin (KLH) and tetanus toxoid (TT). KEY RESULTS: VIB4920 demonstrated linear pharmacokinetics at multiple doses. Lymphocyte, monocyte, cytotoxic T-cell and NK cell counts were not significantly different between treatment groups. B-cell counts reduced dose-dependently and the T-cell dependent antibody response to KLH was suppressed by VIB4920 dose-dependently. The recall response to TT was similar across treatment groups. No thromboembolic events or symptoms of immune system dysfunctionality were observed. CONCLUSIONS AND IMPLICATIONS: VIB4920 demonstrated an acceptable safety profile in monkeys. VIB4920 showed favourable pharmacokinetics, dose-dependent inhibition of a neoantigen-specific immune response and no adverse effects on immune function following long-term use. Our data support the use of VIB4920 in clinical trials.

Talaromycosis (Penicilliosis) in a Cynomolgus Macaque.

A sexually mature Chinese-origin female Macaca fascicularis assigned to the high-dose group in a 26-week toxicology study with an experimental immunomodulatory therapeutic antibody (a CD40 L antagonist fusion protein) was euthanized at the scheduled terminal sacrifice on study day 192. The animal was healthy at study initiation and remained clinically normal throughout the study. On study day 141, abnormal clinical pathology changes were found during a scheduled evaluation; splenomegaly was detected on study day 149 and supported by ultrasound examination. At the scheduled necropsy, there was marked splenomegaly with a nodular and discolored appearance. Cytologic examination of a splenic impression smear revealed yeast-like organisms within macrophages. Histologically, there was disseminated systemic granulomatous inflammation with 2- to 3-µm oval, intracytoplasmic yeast-like organisms in multiple organs identified as Talaromyces (Penicillium) marneffei. This organism, not previously reported as a pathogen in macaques, causes an important opportunistic infection in immunosuppressed humans in specific global geographic locations.

Effects of ICOS+ T cell depletion via afucosylated monoclonal antibody MEDI-570 on pregnant cynomolgus monkeys and the developing offspring.

MEDI-570 is a fully human afucosylated monoclonal antibody (MAb) against Inducible T-cell costimulator (ICOS), highly expressed on CD4+ T follicular helper (TFH) cells. Effects of MEDI-570 were evaluated in an enhanced pre-postnatal development toxicity (ePPND) study in cynomolgus monkeys. Administration to pregnant monkeys did not cause any abortifacient effects. Changes in hematology and peripheral blood T lymphocyte subsets in maternal animals and infants and the attenuated infant IgG immune response to keyhole limpet hemocyanin (KLH) were attributed to MEDI-570 pharmacology. Adverse findings included aggressive fibromatosis in one dam and two infant losses in the high dose group with anatomic pathology findings suggestive of atypical lymphoid hyperplasia. The margin of safety relative to the no observed adverse effect level (NOAEL) for the highest planned clinical dose in the Phase 1a study was 7. This study suggests that women of child bearing potential employ effective methods of contraception while being treated with MEDI-570.

Development of a large-scale chemogenomics database to improve drug candidate selection and to understand mechanisms of chemical toxicity and action.

Successful drug discovery requires accurate decision making in order to advance the best candidates from initial lead identification to final approval. Chemogenomics, the use of genomic tools in pharmacology and toxicology, offers a promising enhancement to traditional methods of target identification/validation, lead identification, efficacy evaluation, and toxicity assessment. To realize the value of chemogenomics information, a contextual database is needed to relate the physiological outcomes induced by diverse compounds to the gene expression patterns measured in the same animals. Massively parallel gene expression characterization coupled with traditional assessments of drug candidates provides additional, important mechanistic information, and therefore a means to increase the accuracy of critical decisions. A large-scale chemogenomics database developed from in vivo treated rats provides the context and supporting data to enhance and accelerate accurate interpretation of mechanisms of toxicity and pharmacology of chemicals and drugs. To date, approximately 600 different compounds, including more than 400 FDA approved drugs, 60 drugs approved in Europe and Japan, 25 withdrawn drugs, and 100 toxicants, have been profiled in up to 7 different tissues of rats (representing over 3200 different drug-dose-time-tissue combinations). Accomplishing this task required evaluating and improving a number of in vivo and microarray protocols, including over 80 rigorous quality control steps. The utility of pairing clinical pathology assessments with gene expression data is illustrated using three anti-neoplastic drugs: carmustine, methotrexate, and thioguanine, which had similar effects on the blood compartment, but diverse effects on hepatotoxicity. We will demonstrate that gene expression events monitored in the liver can be used to predict pathological events occurring in that tissue as well as in hematopoietic tissues.