Rein Therapeutics is a clinical-stage biopharmaceutical company focused on developing treatments for rare lung and fibrosis diseases. Rein's entire active pipeline centers on a single asset: LTI-03, an inhaled peptide drug for idiopathic pulmonary fibrosis (IPF), a progressive fatal lung disease affecting roughly 100,000 people in the U.S. While three drugs are approved to slow IPF progression, none address the underlying destruction of lung epithelial cells. LTI-03 is derived from the Cav1 protein and works via a dual mechanism — reducing fibroblast proliferation (the cells that drive scarring) while also protecting alveolar epithelial cells, which Rein argues differentiates LTI-03 from both approved therapies and most pipeline competitors. LTI-03 has completed Phase 1a and Phase 1b trials, with Phase 1b showing statistically significant reductions in pro-fibrotic biomarkers and an acceptable safety profile in IPF patients. The drug is now in the Phase 2 RENEW trial, a 120-patient randomized controlled study across up to 50 sites in five countries, with interim topline data expected in Q4 2026. LTI-03 holds Orphan Drug Designation in both the U.S. and EU. Rein's second program, LTI-01, has been indefinitely suspended due to capital constraints, as have all preclinical programs. Rein is pre-revenue, funds operations through equity issuances, and operates with just 10 full-time employees, outsourcing clinical and manufacturing work entirely. The company's value is almost entirely contingent on RENEW trial results and its ability to raise capital through that readout.