TY - JOUR T1 - A Potent Human Anti-Eotaxin1 Antibody, CAT-213: Isolation by Phage Display and in Vitro and in Vivo Efficacy JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 1395 LP - 1404 DO - 10.1124/jpet.106.110734 VL - 319 IS - 3 AU - Sarah Main AU - Rachel Handy AU - Jane Wilton AU - Stephen Smith AU - Liz Williams AU - Leila Du Fou AU - John Andrews AU - Louise A. Conroy AU - Richard May AU - Ian Anderson AU - Tristan J. Vaughan Y1 - 2006/12/01 UR - http://jpet.aspetjournals.org/content/319/3/1395.abstract N2 - The CC chemokine, eotaxin1 (CCL11) is an important regulator of eosinophil function. A marked accumulation of eosinophils in tissues has been correlated with the up-regulation of eotaxin1 expression in several diseases. The potential therapeutic value of neutralizing the effects of eotaxin1 in inflammatory conditions (including asthma) is under investigation. A human single-chain fragment variable antibody that neutralizes human eotaxin1 (CAT-212) was produced using antibody phage display and converted to whole antibody IgG4 format (CAT-213). A novel approach to lead optimization in which the length of the variable heavy chain complementarity-determining region 3 was reduced by one amino acid resulted in an increase in potency of >1000-fold compared with the parent anti-eotaxin1 antibody. The optimized antibody binds eotaxin1 with high affinity (80.4 pM) and specificity. CAT-213 and CAT-212 do not bind or neutralize a range of other human proteins including human monocyte chemoattractant protein-1, a structurally similar chemokine. CAT-213 neutralizes the ability of eotaxin1 to cause an increase in intracellular calcium signaling (with an IC50 value of 2.86 nM), migration of CCR3-expressing L1.2 cells (with an IC50 value of 0.48 nM), and inhibition of the eotaxin1-evoked shape change of human eosinophils in vitro (with an IC50 of 0.71 nM). Local administration of CAT-213 to mice (1–100 μg kg–1) attenuates dermal eosinophilia induced by human eotaxin1, achieving >90% inhibition of eosinophil influx. CAT-213 may therefore be of therapeutic value in inhibiting diseases in which eotaxin1 and eosinophils play a major role, for example, severe asthma. ER -