BACKGROUND AND PURPOSEAMG 181 is a human anti-a4b7 antibody currently in phase 1 and 2 trials in subjects with inflammatory bowel diseases. AMG 181 specifically targets the a4b7 integrin heterodimer, blocking its interaction with mucosal addressin cell adhesion molecule-1 (MAdCAM-1), the principal ligand that mediates a4b7 T cell gut-homing. EXPERIMENTAL APPROACHWe studied the in vitro pharmacology of AMG 181, and the pharmacokinetics and pharmacodynamics of AMG 181 after single or weekly i.v. or s.c. administration in cynomolgus monkeys for up to 13 weeks. KEY RESULTSAMG 181 bound to a4b7, but not a4b1 or aEb7, and potently inhibited a4b7 binding to MAdCAM-1 (but not vascular cell adhesion molecule-1) and thus inhibited T cell adhesion. Following single i.v. administration, AMG 181 Cmax was dose proportional from 0.01 to 80 mg·kg -1 , while AUC increased more than dose proportionally. Following s.c. administration, dose-proportional exposure was observed with single dose ranging from 5 to 80 mg·kg -1 and after 13 weekly doses at levels between 20 and 80 mg·kg -1 . AMG 181 accumulated two-to threefold after 13 weekly 80 mg·kg -1 i.v. or s.c. doses. AMG 181 had an s.c. bioavailability of 80%. The linear elimination half-life was 12 days, with a volume of distribution close to the intravascular plasma space. The mean trend for the magnitude and duration of AMG 181 exposure, immunogenicity, a4b7 receptor occupancy and elevation in gut-homing CD4+ central memory T cell count displayed apparent correlations. CONCLUSIONS AND IMPLICATIONSAMG 181 has in vitro pharmacology, and pharmacokinetic/pharmacodynamic and safety characteristics in cynomolgus monkeys that are suitable for further investigation in humans.

Recapitulating human disease pathophysiology using genetic animal models is a powerful approach to enable mechanistic understanding of genotype-phenotype relationships for drug development. Na V 1.7 is a sodium channel expressed in the peripheral nervous system with strong human genetic validation as a pain target. Efforts to identify novel analgesics that are nonaddictive resulted in industry exploration of a class of sulfonamide compounds that bind to the fourth voltage-sensor domain of Na V 1.7. Due to sequence differences in this region, sulfonamide blockers generally are potent on human but not rat Na V 1.7 channels. To test sulfonamide-based chemical matter in rat models of pain, we generated a humanized Na V 1.7 rat expressing a chimeric Na V 1.7 protein containing the sulfonamide-binding site of the human gene sequence as a replacement for the equivalent rat sequence. Unexpectedly, upon transcription, the human insert was spliced out, resulting in a premature stop codon. Using a validated antibody, Na V 1.7 protein was confirmed to be lost in the brainstem, dorsal root ganglia, sciatic nerve, and gastrointestinal tissue but not in nasal turbinates or olfactory bulb in rats homozygous for the knock-in allele (HOM-KI). HOM-KI rats exhibited normal intraepidermal nerve fiber density with reduced tetrodotoxin-sensitive current density and action potential firing in small diameter dorsal root ganglia neurons. HOM-KI rats did not exhibit nociceptive pain responses in hot plate or capsaicin-induced flinching assays and did not exhibit neuropathic pain responses following spinal nerve ligation. Consistent with expression of chimeric Na V 1.7 in olfactory tissue, HOM-KI rats retained olfactory function. This new genetic model highlights the necessity of Na V 1.7 for pain behavior in rats and indicates that sufficient inhibition of Na V 1.7 in humans may reduce pain in neuropathic conditions. Due to preserved olfactory function, this rat model represents an alternative to global Na V 1.7 knockout mice that require time-intensive hand feeding during early postnatal development.

Monoclonal antibodies to B and T lymphocyte attenuator (BTLA) have no effect on in vitro B cell proliferation and act to inhibit in vitro T cell proliferation when presented in a cis, but not trans, format relative to the activating stimulusc ei_4259 and T cells and that some antibodies inhibit anti-CD3e-induced T cell proliferation in vitro, but only when constrained appropriately with a putatively cross-linking reagent. The antibodies had no significant effect on in vitro T cell proliferation in a mixed lymphocyte reaction (MLR) assay nor on in vitro DO11.10 antigen-induced T cell proliferation. None of these antibodies, nor HVEM-Fc, had any significant effect on in vitro B cell proliferation induced by anti-immunoglobulin M antibodies (Ϯanti-CD40) or lipopolysaccharide. We further elucidated the requirements for inhibition of in vitro T cell proliferation using a beads-based system to demonstrate that the antibodies that inhibited T cell proliferation in vitro were required to be presented to the T cell in a cis, and not trans, format relative to the anti-CD3e stimulus. We also found that antibodies that inhibited T cell proliferation in vitro had no significant effect on the antibody captured interleukin-2 associated with the in vivo activation of DO11.10 T cells transferred to syngeneic recipient BALB/c mice. These data suggest that there may be specific structural requirements for the BTLA molecule to exert its effect on lymphocyte activation and proliferation. HVEM is also the receptor for both LIGHT and lymphotoxin-a, which bind in the CRD2 and CRD3 domains, and for CD160, which has been reported to compete with BTLA for binding to HVEM [6]. KeywordsFunctionally, several investigators have provided evidence that signalling through BTLA acts to inhibit T lymphocyte proliferation using a transfected cell co-culture system, plateimmobilized HVEM ligand or monoclonal antibodies Clinical and Experimental Immunology ORIGINAL ARTICLE