BackgroundC3 glomerulopathy (C3G) is characterized by the alternative-pathway (AP) hyperactivation induced by nephritic factors or complement gene mutations. Mice deficient in complement factor H (CFH) are a classic C3G model, with kidney disease that requires several months to progress to renal failure. Novel C3G models can further contribute to understanding the mechanism behind this disease and developing therapeutic approaches.MethodsA novel, rapidly progressing, severe, murine model of C3G was developed by replacing the mouse C3 gene with the human C3 homolog using VelociGene technology. Functional, histologic, molecular, and pharmacologic assays characterize the presentation of renal disease and enable useful pharmacologic interventions in the humanized C3 (C3hu/hu) mice.ResultsThe C3hu/hu mice exhibit increased morbidity early in life and die by about 5–6 months of age. The C3hu/hu mice display elevated biomarkers of kidney dysfunction, glomerulosclerosis, C3/C5b-9 deposition, and reduced circulating C3 compared with wild-type mice. Administration of a C5-blocking mAb improved survival rate and offered functional and histopathologic benefits. Blockade of AP activation by anti-C3b or CFB mAbs also extended survival and preserved kidney function.ConclusionsThe C3hu/hu mice are a useful model for C3G because they share many pathologic features consistent with the human disease. The C3G phenotype in C3hu/hu mice may originate from a dysregulated interaction of human C3 protein with multiple mouse complement proteins, leading to unregulated C3 activation via AP. The accelerated disease course in C3hu/hu mice may further enable preclinical studies to assess and validate new therapeutics for C3G.

Harnessing complement-mediated cytotoxicity by therapeutic antibodies has been limited because of dependency on size and density of antigen, structural constraints resulting from orientation of antibody binding, and blockade of complement activation by inhibitors expressed on target cells. We developed a modular bispecific antibody platform that directs the complement-initiating protein C1q to target cells, increases local complement deposition and induces cytotoxicity against target antigens with a wide-range of expression. The broad utility of this approach to eliminate both prokaryotic and eukaryotic cells was demonstrated by pairing a unique C1q-recruiting arm with multiple targeting arms specific for Staphylococcus aureus , Pseudomonas aeruginosa , B-cells and T-cells, indicating applicability for diverse indications ranging from infectious diseases to cancer. Generation of C1q humanized mice allowed for demonstration of the efficacy of this approach to clear disease-inducing cells in vivo . In summary, we present a novel, broadly applicable, and versatile therapeutic modality for targeted cell depletion.

Knock-in mice with humanized TCR, MHC, and co-receptor genes enable therapeutic human TCR discovery and functional assessment in mice.

INTRODUCTION Paroxysmal Nocturnal hemoglobuinuria (PNH) is a rare, acquired, life-threatening disorder characterised by intravascular hemolysis and increased risk of thrombosis. Current available treatments represent a significant burden to patients and include anti-complement factor 5 (C5) therapies, eculizumab and ravulizumab, both intravenous infusions, or more recently, twice weekly C3 inhibitor, Pegcetacoplan, a subcutaneous (SC) infusion treatment. Pozelimab (REGN3918), a fully human monoclonal immunoglobulin G4 antibody directed against C5, has been shown to bind with high affinity to wild-type and variant (R885H/C) human C5 and block its activity. In a healthy volunteer study (NCT03115996), SC administration of pozelimab was found to be generally well tolerated while providing complete inhibition of ex vivo-assessed hemolytic activity [Weyne J et al. Blood. 2018;S1:1039]. The data suggested that pozelimab may provide control of intravascular hemolysis in patients with active PNH, and thus could provide an important new alternative for patients supporting progression to a first-in-patient study of pozelimab in patients with active PNH. OBJECTIVE To demonstrate a clinically significant reduction in intravascular hemolysis by once-weekly SC administration of pozelimab over 26 weeks of treatment in patients with active PNH. METHODS This is a phase 2, open-label, single-arm, 26-week treatment study in 24 patients with active symptomatic PNH who are naïve to complement inhibitor therapy, or who have received prior treatment with a complement inhibitor but not within 6 months prior to the start of the study (NCT03946748). The treatment regimen consists of pozelimab as a single IV loading dose of 30 mg/kg followed thereafter by weekly SC 800 mg administrations. The effect of pozelimab on intravascular hemolysis (monitored via LDH levels) and transfusion avoidance, as well as safety, is to be assessed from baseline to week 26 (study day 183; only partial data were available for some patients at the time of abstract submission). Pozelimab pharmacodynamics was assessed utilizing a sheep red blood cell (RBC) complement activity assay (CH50) and rabbit RBC complement activity assay (AH50). RESULTS All 24 patients completed the 26-week treatment period with no study drug discontinuation and have been enrolled into an ongoing open-label extension study (NCT04162470). An interim analysis on the first 17 patients was previously reported. All 17 patients had at least 71 days of treatment, with 10 patients receiving treatment for up to 183 days. All enrolled patients had baseline LDH levels ≥2 x upper limit of normal (ULN). Participants were enrolled in two cohorts: Cohort A for dose confirmation and Cohort B for further evaluation of efficacy and safety. Interim Efficacy Analysis As previously reported, treatment with pozelimab led to a rapid and sustained reduction in LDH through study week 26. All 17 patients achieved LDH reduction to below the clinically significant threshold of LDH ≤1.5 x ULN. All but one patient achieved control of intravascular hemolysis (LDH ≤1.5 x ULN) at week 2, and all but one patient achieved normalization of LDH (LDH ≤1.0 x ULN) at week 4. Importantly, one patient who is a carrier of a C5 variant known to be resistant to blockade by eculizumab/ravulizumab demonstrated rapid and sustained normalization of LDH. Interim Safety As previously reported, no serious adverse events or adverse events leading to treatment discontinuation were reported. Common treatment-emergent adverse events included headache (4 patients; 23.5%) and nausea (2 patients; 11.8%). No breakthrough hemolysis events were observed. CONCLUSIONS Pozelimab administered SC once weekly led to the inhibition of intravascular hemolysis in patients with active PNH and was generally well-tolerated. An update to the previously reported interim analysis will be provided. Upon successful completion of the 26-week treatment period, patients are enrolled into an open-label extension study. Disclosures Weyne: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Chaudhari: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Harari: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Miller: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Dain: Regeneron Pharmaceuticals, Inc.: Other: Contractor. Meagher: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Rodgers: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Perlee: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Morton: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Weinreich: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Yancopoulos: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Griffin: Alexion, AstraZeneca Rare Disease: Honoraria, Membership on an entity's Board of Directors or advisory committees; BioCryst Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sobi Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Apellis: Other: Educational grant support.

We describe a Kappa-on-Heavy (KoH) mouse that produces a class of highly diverse, fully human, antibody-like agents. This mouse was made by replacing the germline variable sequences of both the Ig heavy-chain (IgH) and Ig kappa (IgK) loci with the human IgK germline variable sequences, producing antibody-like molecules with an antigen binding site made up of 2 kappa variable domains. These molecules, named KoH bodies, structurally mimic naturally existing Bence-Jones light-chain dimers in their variable domains and remain wild-type in their antibody constant domains. Unlike artificially diversified, nonimmunoglobulin alternative scaffolds (e.g., DARPins), KoH bodies consist of a configuration of normal Ig scaffolds that undergo natural diversification in B cells. Monoclonal KoH bodies have properties similar to those of conventional antibodies but exhibit an enhanced ability to bind small molecules such as the endogenous cardiotonic steroid marinobufagenin (MBG) and nicotine. A comparison of crystal structures of MBG bound to a KoH Fab versus a conventional Fab showed that the KoH body has a much deeper binding pocket, allowing MBG to be held 4 Å further down into the combining site between the 2 variable domains.

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Grammatical Evolution is a data-driven, model-induction tool, inspired by the biological gene-to-protein mapping process. This study examines the potential of Grammatical Evolution to uncover useful technical trading rulesets for intra-day equity trading. The form of these rule-sets is not specified ex-ante but emerges by means of an evolutionary process. High-frequency price data drawn from United States stock markets is used to train and test the model. The findings suggest that the developed rules earn positive returns in holdout test periods, and that the sizes of these returns are critically impacted by the choice of position exit-strategy.