Sanjay Shukla
Analyst · RBC Capital Markets. You may proceed
Thank you, Ashlee. Good afternoon, everyone, and thank you for joining us for our fourth quarter and full year 2023 results conference call. At aTyr, we are leveraging evolutionary intelligence to translate tRNA synthetase biology into new therapies for fibrosis and inflammation. Our lead therapeutic candidate, Efzofitimod, is a first-in-class biologic immunomodulator based on a naturally occurring, long enriched splice variant of the tRNA synthetases, HARS. Efzofitimod selectively modulates activated myeloid cells via neuropilin-2 or NRP-2 to resolve inflammation without immune suppression and potentially prevent the progression of fibrosis. We're developing Efzofitimod as a treatment for patients with interstitial lung disease or ILD, a group of rare immune-mediated disorders that can cause chronic inflammation and fibrosis of the lungs. 2023 was an important year for aTyr as we progressed and expanded our Efzofitimod clinical development program, which now includes two ongoing clinical studies, the Phase 3 EFZO-FIT study in patients with pulmonary sarcoidosis, a major form of ILD; and the Phase 2 EFZO-CONNECT study in patients with ILD related to systemic sclerosis, which is known as SSc or more commonly, scleroderma. Throughout the past year, we have also greatly enhanced our mechanistic understanding of the way in which Efzofitimod is confirming its anti-inflammatory effects. NRP-2 is highly expressed on activated immune cells doing an inflammatory response, notably myeloid cells, including monocytes and macrophages. By binding NRP-2, Efzofitimod guides the differentiation of monocytes at the site of inflammation into a macrophage subtype that is less pro-inflammatory to resolve aberrant inflammation. Dysregulated inflammation is a hallmark of myelo-driven diseases such as ILD, where persistent, uncontrolled inflammation can lead to the progression of fibrosis. With this new understanding, we now have even greater clarity and confidence as to why Efzofitimod may represent a breakthrough in treatment for ILD. Our lead indication for Efzofitimod is pulmonary sarcoidosis, the most prevalent form of ILD, where approximately 70% of patients will have symptomatic disease and nearly 20% will develop lung fibrosis. Current standard of care is primarily oral corticosteroids, a highly toxic treatment that has limited clinical evidence, is broadly immunosuppressive, and comes with side effects resulting in a high disease burden for patients. EFZO-FIT is a global pivotal Phase 3 study evaluating Efzofitimod compared to placebo in the context of a four steroid taper in patients with pulmonary sarcoidosis. This study is currently enrolling at more than 90 centers in nine countries. We're pleased with the progress we've made thus far with this study, which is expected to be the largest interventional study ever conducted in sarcoidosis. Completing enrollment in EFZO-FIT is our primary focus and we anticipate doing so in the second quarter of this year. In the past few months as patients have completed the 52-week EFZO-FIT study, we've received multiple inquiries from study principles -- study principal investigators, or PIs, whose patients have requested to continue treatment once they completed the trial. While aTyr PIs and patients are all blinded to what treatment patients received as part of the study, either Efzofitimod or placebo, the feedback we've received has suggested that some patients have performed well and want to continue on study drug rather than returning to the treatment regimen they had prior to the study. For some patients that may entail resuming or increasing steroid dose, which many patients are reluctant to do. Based on this feedback, we decided to implement an individual patient expanded access program or TAP for patients who complete EFZO-FIT. This individual patient EAP is design to allow access to Efzofitimod for patients who all have or are in the process of completing EFZO-FIT beyond the duration of the clinical trial. The company PIs and patients will remain blinded to treatment that occurred as part of EFZO-FIT. Safety is a key component of any EAP. We were able to implement this program based on the existing safety database from prior Efzofitimod clinical studies and additional safety and tolerability data from a Data Safety & Monitoring Board or DSMB review of data from EFZO-FIT, which included the evaluation of patients that completed 52 weeks of treatment. The DSMB review recommended the study proceed without modification, suggesting no major safety concerns. And while many types of EAPs are typically implemented after data from a study has been unblinded, we decided to implement this individual patient EAP early not only based on feedback and demand, but in part to continue to support those patients who have dedicated their time and entrusted us with their health by participating in this important study. This program reflects our ongoing commitment to the sarcoidosis community as we work to develop a safe and effective treatment for those in need. Our second indication for Efzofitimod is SSc-ILD. SSc is a form of connective tissue disease where ILD commonly occurs and is a leading cause of mortality. Current treatment options are limited and like sarcoidosis, do not treat the underlying disease or improve quality of life. EFZO-CONNECT is a Phase 2 proof-of-concept study evaluating Efzofitimod compared to placebo in patients with SSc-ILD. This study, which dosed the first patient last quarter, is currently open for enrollment at multiple centers in the US. We're focused on generating data from this study in 2024, and we expect to provide an update on the study later this year. We estimate that the two indications that comprise our current clinical program for Efzofitimod, pulmonary sarcoidosis and SSc-ILD collectively represent a potential $2 billion to $3 billion global market opportunity. This does not include any upside potential and other forms of the more than 200 ILDs, where Efzofitimod's unique mechanism of action to address complex immune pathology and desirable safety profile may be able to disrupt standard of care. While our primary focus is our clinical program for Efzofitimod, we continue to leverage our intellectual property or IP estate covering domains from all 20 human tRNA synthetases and utilize our platform as an engine to generate new pipeline candidates. tRNA synthetases are ancient essential proteins that have evolved novel domains to regulate diverse pathways, extracellularly, in humans. By identifying extracellular receptors and signaling pathways for these domains, we can elucidate the role these proteins play in cellular response and explore disease areas where they may have therapeutic benefit. Our two most advanced tRNA synthetases candidates in preclinical development are ATYR0101 and ATYR0750, both of which have specific interactions with targets that have implications in fibrosis. These targets include latent transforming growth factor beta binding protein one or LTBP1 and fibroblast growth factor receptor four or FGFR4, respectively. ATYR0101, which is derived from a domain of the tRNA synthetases DARS exerts its anti-fibrotic effects by selectively inducing a proptosis of myofibroblasts targeting a key hallmark of fibrosis pathology, which is the persistence of activated myofibroblasts. This mechanism may support broad therapeutic application in indications like lung, liver, and kidney fibrosis. The hidden biology that we have been able to unlock from our platform continues to inspire us, including the way in which some of these appended domains like Efzofitimod interact extracellularly with previously under the radar targets like NRP-2 and in particular, its role as an immune regulator or bind more well-known targets in unique ways like ATYR0101 and ATYR0750. This platform, which is based on signaling pathways that have evolved over billions of years to maintain homeostasis is an excellent example of bio innovation and has the potential to disrupt traditional drug discovery, a process that is increasingly reliant on exploiting existing signaling pathways to generate therapies. Our conviction to the potential of tRNA synthetases biology to lead the transformative medicines continues to grow stronger as our research advances. I'll now turn it over to our Chief Financial Officer, Jill Broadfoot, to review our financial results.