Rein Therapeutics Announces New Translational Data on its Novel Therapy for Idiopathic Pulmonary Fibrosis

Rein Therapeutics recently announced the publication of novel data on its lead drug candidate, LTI-03, in iScience, a peer-reviewed, open-access journal published by Cell Press.

The paper, titled LTI-03 peptide demonstrates anti-fibrotic activity in ex vivo lung slices from IPF patients, reports how LTI-03 was tested directly on lung tissue donated by patients with idiopathic pulmonary fibrosis (IPF) who underwent lung transplant. In this model, LTI-03 showed signs of reducing scarring and protecting lung cells, reinforcing its potential as an important new therapy.

Key Highlights

1. The study used real lung tissue donated by IPF patients. These samples continued to show scarring activity for several days, making them a highly relevant way to test new therapies.
2. LTI-03 reduced multiple scarring pathways (including TGFβ, VEGF, PDGF, and FGF), while also lowering collagen production and inflammatory signals in diseased lung tissue.
3. Unlike nintedanib, the FDA-approved standard-of-care drug, LTI-03 achieved these effects without causing cell damage or death in patient samples, reinforcing the drug’s strong safety profile.
4. The findings add to the growing body of evidence that LTI-03 has the potential to become a meaningful new therapy for IPF.

Brian Windsor, PhD, Chief Executive Officer of Rein Therapeutics, said “Using a highly relevant translational model, this peer-reviewed publication provides further validation of LTI-03’s broad anti-fibrotic effects in IPF lung tissue. These data support our ongoing Phase 2 RENEW trial, where we are evaluating LTI-03 in patients living with IPF, a disease with very limited treatment options and high unmet need.”

IPF is a progressive fibrotic lung disease that affects approximately 100,000 people in the US and more than 70,000 in the UK. Median survival is just 3-5 years from diagnosis, even with currently approved therapies. The global market for IPF treatments is projected to exceed $11 billion by 2031, underscoring the urgent need for more effective approaches.

Rein recently announced regulatory approval from the UK’s MHRA to initiate the Phase 2 RENEW trial of LTI-03. The trial will evaluate safety, tolerability, and changes in lung function in up to 120 patients, with initial data expected in 2026.

The full article can be found here: https://www.cell.com/iscience/fulltext/S2589-0042(25)01698-0

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 US and is in clinical development. 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 US and EU and Fast Track Designation in the US.