ABSTRACT The goal of this STTR proposal is to develop a novel anti-fibrotic agent suitable for oral administration which could be used to safely and effectively treat Systemic Sclerosis (SSc), or Systemic Scleroderma patients. SSc is one of the most disabling and lethal immune-mediated rheumatic disorders. SSc is a rare disease, affecting 40,000-150,000 people in the United States and conferring a five to eight-fold higher risk for mortality. It is a heterogeneous, multiorgan disease characterized by vascular endothelial alterations that results in chronic inflammation and immune responses leading to progressive fibrosis and organ(s) failure. Major impacted organs are skin, lungs, kidneys, and vasculature system. In SSc patients, vascular endothelial cell injury characteristically precedes inflammation and autoimmune responses that stimulates the progression into tissue fibrosis scaring. The leading cause of early death (5 years from diagnosis) is interstitial lung disease (ILD). Treatment routinely relies on Nintedanib (TK inhibitor) and Tocilizumab (IL-6 mAb), and symptomatic treatments but these have limited efficacy, and tolerability and/or toxicity issues. As of today, disease fibrosis progression and mortality rate for SSc remains greater than for any other rheumatic disease; highlighting the clear unmet medical need for disease modifying therapies that will prevent or reduce the damage to major organs. Targeting repair and regeneration of the vascular endothelial cell injury via the Apelinergic System (apelin/APJ) signaling pathway provides a unique and novel opportunity for the treatment of SSc patients (as of today vascular endothelium repair and regeneration is an under targeted area in SSc drug development). The system is well- established as an endogenous anti-injury and organ-protective mechanism that is activated post vascular endothelium injury and is expressed in all SSc disease impacted organs. APIE Therapeutics, in collaboration with RTI International, has identified a lead anti-fibrotic drug candidate, apelin agonist APT101, for the treatment of lung fibrosis. First, in a bleomycin-induced lung fibrosis mouse model therapeutic treatment with APT101 significantly inhibited the production of collagen in the lungs (a hallmark of lung fibrosis progression), as detected via the Hydroxyproline Assay, and primary end point of the study. Second, APT101 showed significantly reduced fibrosis in myocardial infarction animal studies (mice and rats) and significantly reduced biomarker responses in ex-vivo human cell co-culture disease models relevant to lung, skin, and kidney fibrotic diseases. Taken together, this evidence suggests that activation of the apelinergic system has the potential to disrupt the pathogenic cascade responsible for progressive fibrosis in SSc. Our aims for this proposal are obtain preclinical data in validated SSc models: 1) in-vivo efficacy model and, 2) ex-vivo human tissue model. The results from Aims 1 and 2 will inform a data driven decision regarding APT101 IND initial indication and subsequent plans for Phases II proposal.

PROJECT NARRATIVE Systemic sclerosis, or Systemic scleroderma, is a progressive, disabling, and often deadly disease. The leading cause of disability and death from scleroderma results from damage to the lungs, heart, kidney and skin, and there is a clear need for new therapies that will prevent, reduce, or repair damage to the major organs. APIE Therapeutics is developing a new drug that has the potential to repair and reverse some of the damage caused by systemic scleroderma and improve prognosis and survival.