Effects Of The Autotaxin Inhibitor Ziritaxestat On Skin And Lung Fibrosis In A Murine Graft-Versus-Host Disease Model Of Systemic Sclerosis

Background:There is an unmet medical need for new drugs to treat systemic sclerosis (SSc). Autotaxin (ATX) is a widely expressed enzyme that regulates diverse cellular processes, including proliferation, differentiation and migration, and has been implicated in the pathogenesis of SSc. Targeting ATX is a promising new strategy for treating SSc. The autotaxin inhibitor ziritaxestat (GLPG1690) is a potential first-in-class disease-modifying drug for SSc that has been shown to improve skin score in the Phase 2a NOVESA (NCT03798366) trial in patients with SSc.Objectives:To investigate the effects of ziritaxestat in a chronic graft-versus-host disease (cGvHD) murine model of SSc.Methods:Effects of ziritaxestat (10 or 30 mg/kg twice daily [bid]) on disease activity were assessed in a cGvHD murine model of SSc (allogeneic bone marrow transplantation [BMT] with B10.D2 donor and BALB/c recipient; syngeneic mice as controls). Ziritaxestat or nintedanib (60 mg/kg once daily [qd]) as active comparator was administered 21 d after BMT and continued for 35 d. Effects of ziritaxestat were assessed by clinical monitoring, histologic assessment of skin and lungs (dermal thickness, Ashcroft scores and collagen-covered area), immunofluorescence staining with Trichrome and Sirius Red for myofibroblasts, and biochemical analysis of collagen content, as measured by hydroxyproline levels.Results:Ziritaxestat 30 mg/kg bid for 35 days significantly reduced the clinical cutaneous score in the murine cGvHD model by 57% (p<0.05) compared with vehicle, and to a similar extent when compared with nintedanib 60 mg/kg (38%; p<0.05). Dermal accumulation of collagen and dermal thickness (Figure) were reduced with ziritaxestat 10 and 30 mg/kg compared with vehicle. At 30 mg/kg, ziritaxestat reversed the increase in the allogeneic model (p<0.001), returning dermal thickness to the levels in non-fibrotic control mice. Ziritaxestat also significantly reduced pulmonary fibrosis in the cGvHD model, with reductions in the fibrotic lung area (ziritaxestat 10 and 30 mg/kg; p<0.001 for both) and Ashcroft scores (ziritaxestat 30 mg/kg; p<0.05). Ziritaxestat was generally well tolerated.Conclusion:Ziritaxestat improved the histological, biochemical and clinical symptom readouts of dermal and pulmonary fibrosis in a murine model, consistent with a broad and rapid disease-modifying effect in SSc.Acknowledgements:This study was funded by Galapagos NV (Mechelen, Belgium). Medical writing/editorial support was provided by Ian Faulkner, PhD (Aspire Scientific, Bollington, UK) funded by Galapagos NV.Disclosure of Interests:Yun Zhang Employee of: 4D Science, Lena Summa Employee of: 4D Science, Bertrand Heckmann Shareholder of: Galapagos, Employee of: Galapagos, Jörg H.W. Distler Shareholder of: 4D Science, Consultant of: Actelion, Active Biotech, Anamar, ARXX, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GlaxoSmithKline, Inventiva, JB Therapeutics, Medac, Pfizer, RuiYi and UCB, Grant/research support from: Anamar, Active Biotech, Array Biopharma, ARXX, aTyr, Bristol Myers Squibb, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GlaxoSmithKline, Inventiva, Novartis, Sanofi-Aventis, RedX and UCB