THU0073 14-3-3ETA as a Novel RA Drug Target: Anti-14-3-3ETA Monoclonal Antibody Delays the Onset and Mitigates the Severity of Arthritis in CIA MICE
Authors: A. Abulrob, M. Mercier, S. Corluka, R. MacKenzie, S. Raphael, S. Michienzi, J. Savill, Y. Gui, W.P. Maksymowych, A. Marotta
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> 14-3-3η is a joint-derived soluble biomarker that is available as a diagnostic test in the US, Canada and Europe. As an extracellular ligand 14-3-3η potently and dose-dependently upregulates the expression of multiple factors including TNFα, IL-6 and RANKL and its clinical expression is associated with joint damage progression risk. Several disease modifying agents are available for the treatment of RA with remission efficacy rates around 30% with none that have direct companion biomarkers for patient selection and therapy response monitoring. Since RA is driven by multiple factors to varying degrees, within and between patients along the disease course, personalized medicine that enables the specific targeting and measurement of disease potentiators, such as 14-3-3η, is highly desirable. <h3>Objectives</h3> To evaluate the <i>in vivo</i> feasibility of targeting 14-3-3η with a monoclonal antibody drug candidate to mitigate the onset and severity of collagen-induced arthritis (CIA) in mice. <h3>Methods</h3> 27 DBA/1 mice were randomized to four study groups: non-induced mice (negative control, N=5), 0.5 mg/kg of dexamethasone group (positive control, N=6), vehicle (saline) injected mice (placebo group, N=10), and the treatment arm that was administered 10 mg/kg of 14-3-3η mAb (N=6). Treatments were initiated 2 days prior to immunization with collagen and administered daily for 6 weeks. A collagen booster was injected on day 18 of the study for all immunized mice. Arthritis scores were determined by an established and standardized chart evaluating inflammation and swelling of each paw. Each paw was scored daily from 0 to 4 based on the severity of the swelling. All animals were sacrificed 42 days after the beginning of the treatments as predetermined. No animals reached a score of 4 being the exclusion point where the animal is euthanized due to severity of the swelling. Student t-test was performed to examine differences (onset CIA score, maximum score and end score) amongst the two groups and the Kruskal Wallis test was used to compare group daily score differences over the course of disease. <h3>Results</h3> Non-induced (negative control) and Dexamethasone (positive control) mice did not develop visible signs of arthritis over the course of disease while 100% of the mice within the saline arm did. 17% of the mice in the 14-3-3η mAb group did not develop any signs of arthritis. The CIA score for the 14-3-3η mAb arm had significantly lower CIA onset scores (0.83±0.41 vs 7±1.57, p=0.0119), maximum CIA scores (2.8±1.48 vs 5.3±1.83, p=0.0052) and end CIA scores (2.2±1.79 vs 4.3±1.7, p=0.0197) than the saline treated groups. Figure 1 further demonstrates that 14-3-3η mAb treated mice have significantly lower disease over the disease course than animals in the saline group, p&lt;0.01. No animals reached a predetermined endpoint being the score of 4 on the RA chart and all were sacrificed on day 40 of the study. <h3>Conclusions</h3> 14-3-3η is a mechanistic joint damage factor involved in the pathogenesis of RA that has diagnostic and prognostic utility. It represents a novel RA personalized medicine drug target based on anti-14-3-3η mAb efficacy in delaying the onset and reducing the severity of arthritis in CIA. <h3>Disclosure of Interest</h3> A. Abulrob Employee of: National Research Council, M. Mercier Employee of: National Research Council, S. Corluka Employee of: National Research Council, R. MacKenzie Employee of: National Research Council, S. Raphael Employee of: National Research Council, S. Michienzi Employee of: Augurex Life Sciences Corp, J. Savill Employee of: Augurex Life Sciences Corp, Y. Gui Employee of: Augurex Life Sciences Corp, W. Maksymowych Consultant for: Augurex Life Sciences Corp, (Co-inventor of 14-3-3η), A. Marotta Employee of: Augurex Life Sciences Corp, (Co-inventor of 14-3-3η)