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Deficiency of interleukin (IL)-36 receptor antagonist (DITRA) syndrome is a rare autosomal recessive disease caused by mutations in IL36RN. IL-36R is a cell surface receptor and a member of the IL1R family that is involved in inflammatory responses triggered in skin and other epithelial tissues. Accumulating evidence suggests that IL-36R signaling may play a role in the pathogenesis of psoriasis. Therapeutic intervention of IL-36R signaling offers an innovative treatment paradigm for targeting epithelial cell-mediated inflammatory diseases such as the life-threatening psoriasis variant called generalized pustular psoriasis (GPP). We report the discovery and characterization of MAB92, a potent, high affinity anti-human IL-36 receptor antagonistic antibody that blocks human IL-36 ligand (α, β and γ)-mediated signaling. In vitro treatment with MAB92 directly inhibits human IL-36R-mediated signaling and inflammatory cytokine production in primary human keratinocytes and dermal fibroblasts. MAB92 shows exquisite species specificity toward human IL-36R and does not cross react to murine IL-36R. To enable in vivo pharmacology studies, we developed a mouse cross-reactive antibody, MAB04, which exhibits overlapping binding and pharmacological activity as MAB92. Epitope mapping indicates that MAB92 and MAB04 bind primarily to domain-2 of the human and mouse IL-36R proteins, respectively. Treatment with MAB04 abrogates imiquimod and IL-36-mediated skin inflammation in the mouse, further supporting an important role for IL-36R signaling in epithelial cell-mediated inflammation.

Herein, we describe the generation and characterization of BI 655066, a novel, highly potent neutralizing anti-interleukin-23 (IL23) monoclonal antibody in clinical development for autoimmune conditions, including psoriasis and Crohn's disease. IL23 is a key driver of the differentiation, maintenance, and activity of a number of immune cell subsets, including T helper 17 (Th17) cells, which are believed to mediate the pathogenesis of several immune-mediated disorders. Thus, IL23 neutralization is an attractive therapeutic approach. Designing an antibody for clinical activity and convenience for the patient requires certain properties, such as high affinity, specificity, and solubility. These properties were achieved by directed design of the immunization, lead identification, and humanization procedures. Favorable substance and pharmacokinetic properties were established by biophysical assessments and studies in cynomolgus monkeys.

It has been almost a half-century since the work of Cohen-Bazire et al. (13) demonstrated that oxygen regulates bacteriochlorophyll synthesis in the purple nonsulfur photosynthetic bacteria. However, the mechanism by which oxygen regulates this pathway has been difficult to elucidate. For Rhodobacter capsulatus, it has been shown that a bchH mutant accumulates much more protoporphyrin IX when grown under low oxygen tension than under high oxygen tension (6), indicating that oxygen regulates some step in the common tetrapyrrole pathway (Fig. ​(Fig.1).1). Rebeiz and Lascelles (39) proposed that oxygen inhibits the chelation of magnesium into the protoporphyrin ring, the first step in the branch leading to bacteriochlorophyll. The accumulating protoporphyrin IX would be diverted to heme, which would feedback inhibit aminolevulinate synthase. Inhibition of this enzyme would reduce carbon-flow over the common tetrapyrrole pathway. FIG. 1. The common tetrapyrrole pathway in R. capsulatus. Dashed lines denote multistep pathways. This theory was tested in R. capsulatus by growing a bchH mutant (AJB456) under high and low oxygen concentrations in the presence of exogenous aminolevulinate (5). Surprisingly, protoporphyrin IX accumulation was still regulated by oxygen. However, when exogenous porphobilinogen, the second intermediate in the pathway, was added to a culture of the bchH mutant, protoporphyrin IX accumulation was no longer regulated by oxygen (5). This observation indicated that the major oxygen-regulated control point in the common tetrapyrrole pathway is not the synthesis of aminolevulinate. Rather, it appears that oxygen regulates the second step in the pathway, the conversion of aminolevulinate to porphobilinogen. This is reminiscent of the situation in Bradyrhizobium japonicum, where transcription of the hemB gene is regulated by oxygen (10). The lack of a hemC mutant has made it difficult to confirm and extend these results. The most straightforward way to determine whether oxygen regulates porphobilinogen formation in R. capsulatus would be to measure porphobilinogen levels in a hemC mutant. Such a mutant would lack porpobilinogen deaminase and would therefore accumulate porphobilinogen. In this study, the construction and characterization of a hemC mutant is detailed. Using this mutant, it was determined that the intracellular porphobilinogen level is regulated by oxygen tension. Since the situation in R. capsulatus appears to be similar to that of B. japonicum (10), transcriptional regulation of the hemB gene was investigated. We report here that hemB transcription is not regulated in response to oxygen tension nor is the activity of porphobilinogen synthase feedback inhibited by either hemin or protoporphyrin IX. We did observe, however, that intracellular hemin levels appear to influence carbon flow over the common tetrapyrrole pathway. Additionally, R. capsulatus has a novel enzyme, aminolevulinate dehydrogenase, which reduces aminolevulinate to aminohydroxyvalerate. The regulation of porphobilinogen levels appears to be mediated by a combination of feedback inhibition of aminolevulinate synthase by hemin and by diverting aminolevulinate from the common tetrapyrrole pathway.

Dabigatran etexilate is a direct thrombin inhibitor and used widely as an anticoagulant for the prevention of stroke in patients with atrial fibrillation. However, anticoagulation therapy can be associated with an increased risk of bleeding. Here, we present data on the identification, humanization, and in vitro pharmacology of an antidote for dabigatran (aDabi-Fab). The X-ray crystal structure of dabigatran in complex with the antidote reveals many structural similarities of dabigatran recognition compared with thrombin. By a tighter network of interactions, the antidote achieves an affinity for dabigatran that is ~350 times stronger than its affinity for thrombin. Despite the structural similarities in the mode of dabigatran binding, the antidote does not bind known thrombin substrates and has no activity in coagulation tests or platelet aggregation. In addition we demonstrate that the antidote rapidly reversed the anticoagulant activity of dabigatran in vivo in a rat model of anticoagulation. This is the first report of a specific antidote for a next-generation anticoagulant that may become a valuable tool in patients who require emergency procedures.

Background Costimulatory molecule pair CD40-CD40L plays a central role not only in immune cell interactions but also in immune-non immune cell activation. Targeting this pathway has generated great interest but early attempts to target CD40L failed mainly due to thrombotic complications observed in the clinic. In addition, developing a potent truly antagonistic CD40 antibody has proven to be challenging. Objectives Here we describe the preclinical characterization of BI 655064, an anti-human CD40 mAb that is being developed for the treatment of autoimmune disorders. BI 655064 is engineered as a human IgG1 molecule with a mutated Fc region to abrogate effector function. Methods Binding of BI 655064 to CD40 expressed on primary B cells was measured by flow cytometry. The ability of BI 655064 to block CD40L-induced B cell proliferation in vitro was measured by tritium uptake, while blockade of endothelial and DC activation was measured by inhibition of cytokine release. A subcutaneous PK/PD study in the cynomolgus monkey was performed to establish correlations between BI 655064 exposure, target coverage using a receptor occupancy assay and pharmacodynamic effects using an ex vivo CD54-induction assay. In vivo blockade of B cell function was also tested in a human-peripheral blood lymphocyte (huPBL) induced SCID mouse model of graft-versus-host disease (GvHD) and in cynomolgus monkeys immunized with keyhole limpet hemocyanin (KLH). Results In human whole blood, BI 655064 binds to CD40 on B cells (EC 90 of 6.85 nM ±0.74). Blockade of CD40L-induced B cell proliferation was observed at an average IC 50 of 0.4 nM. Inhibition of CD40L mediated cytokine release was observed in DCs (IC 50 =0.25 nM and 0.59 nM for TNFα and IL12/23p40, respectively) and to verify effects beyond immune cells, BI655064 was tested in CD40L stimulated endothelial cell cultures. Binding of BI 655064 to human platelets did not induce or augment platelet activation as determined by in vitro induction of CD62P. In the PK/PD study, cynomolgus monkeys dosed with greater than 1 mg/kg of BI 655064 exhibited complete blockade of ex vivo CD54 upregulation corresponding to full CD40 target coverage on B cells. In vivo , BI 655064 demonstrated clear effects on B cell function in the GvHD model where both human IgM and IgG responses were completely abrogated. As part of a repeat dose tolerability study, BI 655064 given to cynomolgus monkeys prior to immunization with KLH resulted in inhibition of KLH-specific IgM and IgG antibody responses. At doses of 5 mg/kg and above, germinal center size was decreased microscopically in Peyer9s patches, lymph nodes, spleens and tonsils in treated monkeys. Evaluation of platelet function in cynomolgus monkeys dosed with BI 655064 did not reveal any effects on ex vivo platelet activation or aggregation. Conclusions BI 655064 is a humanized antagonistic anti-CD40 mAb which is to be tested in human clinical trials for autoimmune disorders to establish safety and efficacy. BI 655064 demonstrated relevant pharmacologic in vitro and in vivo activity, blocking CD40-related functions at clinical dosing levels of >1 mg/kg in animal models. Disclosure of Interest K. Ralph Employee of: Boehringer Ingelheim Pharmaceuticals, A. Nicoletti Employee of: Boehringer Ingelheim Pharmaceuticals, E. Musvasva Employee of: Boehringer Ingelheim Pharmaceuticals, S. Cannan Employee of: Boehringer Ingelheim Pharmaceuticals, S. VanTongeren Employee of: Boehringer Ingelheim Pharmaceuticals, D. Blanset Employee of: Boehringer Ingelheim Pharmaceuticals, S. Brodeur Employee of: Boehringer Ingelheim Pharmaceuticals, J. Ahlberg Employee of: Boehringer Ingelheim Pharmaceuticals, H. Li Employee of: Boehringer Ingelheim Pharmaceuticals, S. Fogal Employee of: Boehringer Ingelheim Pharmaceuticals, S. Desai Employee of: Boehringer Ingelheim Pharmaceuticals, K. O9Shea Employee of: Boehringer Ingelheim Pharmaceuticals, R. Kroe-Barrett Employee of: Boehringer Ingelheim Pharmaceuticals, E. Mainolfi Employee of: Boehringer Ingelheim Pharmaceuticals, G. Nabozny: None declared, H. Wu Employee of: Boehringer Ingelheim Pharmaceuticals, G. Hansen Employee of: Boehringer Ingelheim Pharmaceuticals, K. Canada Employee of: Boehringer Ingelheim Pharmaceuticals, S. Singh Employee of: Boehringer Ingelheim Pharmaceuticals, X. Zhu Employee of: Boehringer Ingelheim Pharmaceuticals, M. Ramanujam Employee of: Boehringer Ingelheim Pharmaceuticals, C. Grimaldi Employee of: Boehringer Ingelheim Pharmaceuticals