AUSTIN, Texas — Rein Therapeutics (“Rein”) (NASDAQ: RNTX), a biopharmaceutical company advancing a novel pipeline of first-in-class medicines to address significant unmet medical needs in orphan pulmonary and fibrosis indications, announced that a new preprint has been posted to medRxiv describing clinical and translational findings from an inhaled, dose-escalation study of Rein’s lead drug candidate, LTI-03, in idiopathic pulmonary fibrosis (IPF).
The preprint, titled “Inhaled LTI-03 for Idiopathic Pulmonary Fibrosis: A Randomized Dose Escalation Study,” was authored by an international team of investigators, including Philip L. Molyneaux, MD, Nikhil A. Hirani, MD, Robert J. Kaner, MD, Cory M. Hogaboam, PhD, BreAnne MacKenzie, PhD, Andreas Gunther, MD, and others.
The report describes how inhaled LTI-03 was evaluated in IPF patients to assess safety, pharmacokinetics, and biological activity. According to the authors, LTI-03 was generally well tolerated, and samples collected from treated patients showed reductions in multiple fibrosis-associated biomarkers. These biomarkers include proteins and inflammatory signals linked to disease progression, offering evidence that the drug is reaching the lung and engaging its intended targets.
The investigators also reported that LTI-03 helped preserve alveolar epithelial type II (AT2) progenitor cells, which are essential for lung repair and regeneration. Current IPF therapies primarily focus on slowing progression rather than protecting or restoring these cells.
Brian Windsor, Ph.D., Chief Executive Officer of Rein Therapeutics, commented, “This new data adds to a growing body of evidence supporting LTI-03’s potential as a differentiated therapy for IPF. We’re encouraged to see consistent signals across preclinical and clinical work showing that LTI-03 may not only reduce fibrosis but also help protect the lung cells required for healing. IPF patients urgently need better options, and this work reinforces why we are advancing LTI-03 through our Phase 2 RENEW trial.”
Link to full article:
https://www.medrxiv.org/content/10.1101/2025.10.28.25338981v1
About LTI-03
LTI-03 is a first-in-class, inhaled peptide therapy derived from Caveolin-1 biology, a key regulator of fibrotic signaling. The drug is designed to inhibit lung scarring while preserving alveolar progenitor cells that are critical for tissue repair and regeneration.
Early data suggests that LTI-03 may represent a dual-acting approach: slowing fibrosis and promoting lung healing.
About Idiopathic Pulmonary Fibrosis (IPF)
IPF is a chronic, progressive lung disease characterized by irreversible scarring that impairs the ability to breathe. Despite current FDA-approved therapies aimed at slowing progression, median survival remains only 3–5 years from diagnosis. By some estimates, the global market for fibrosis treatments is projected to exceed $11 billion by 2031, underscoring the urgent need for new and more effective options.
About Rein Therapeutics
Rein Therapeutics is a clinical-stage biopharmaceutical company advancing a novel pipeline of first-in-class therapies to address significant unmet medical needs in orphan pulmonary and fibrosis indications. Rein’s lead product candidate, LTI-03, is a novel, synthetic peptide with a dual mechanism targeting alveolar epithelial cell survival as well as inhibition of profibrotic signaling. LTI-03 has received Orphan Drug Designation in the U.S. Rein’s second product candidate, LTI-01, is a proenzyme that has completed Phase 1b and Phase 2a clinical trials for the treatment of loculated pleural effusions. LTI-01 has received Orphan Drug Designation in the U.S. and E.U. and Fast Track Designation in the U.S. For more information visit https://www.reintx.com/ or follow the company on X/Twitter.
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