Rein Therapeutics Announces Publication of Landmark LTI-03 Clinical Data in Nature Communications

• Data support ongoing Phase 2 “RENEW” trial
• First-in-human clinical study produced measurable reductions in multiple markers of lung scarring and inflammation in IPF patients
• Study confirms LTI-03 was safe and well-tolerated

AUSTIN, Texas, Aug. 04, 2026 (GLOBE NEWSWIRE) -- Rein Therapeutics, Inc. ("Rein" or the "Company") (NASDAQ: RNTX), a clinical-stage biopharmaceutical company advancing a novel pipeline of first-in-class medicines for orphan pulmonary and fibrosis indications, today announced publication of clinical data from its first-in-human study of LTI-03 in Nature Communications, one of the world's most prestigious peer-reviewed scientific journals. The paper, titled "Inhaled LTI-03 for Idiopathic Pulmonary Fibrosis: A Randomized Dose Escalation Study," is available at [https://www.nature.com/articles/s41467-026-75291-3]. These data were previously reported as a preprint in November 2025. Publication in Nature Communications following independent peer review represents significant scientific validation of the study design, data, and conclusions.

The randomized, placebo-controlled study enrolled 24 IPF patients who received inhaled LTI-03 at 5 or 10 mg/day, or placebo, for 14 days. LTI-03 was well-tolerated at both doses, with no treatment-related discontinuations and only mild or moderate side effects. No systemic absorption was detected, consistent with LTI-03's design as a therapy that acts locally in the lung. This would potentially provide more benefit than currently approved oral IPF medications.

Using samples collected directly from deep within patients' lungs, researchers measured proteins and inflammatory signals known to drive the progression of IPF. LTI-03 significantly reduced multiple markers of lung scarring and inflammation at both doses tested, including a key driver of scar-producing cell activation (IL-11) and an inflammatory signal elevated in the lungs of IPF patients that promotes fibrosis (TSLP). At the higher dose, LTI-03 additionally reduced a direct marker of collagen deposition, the primary component of scar tissue (COL1A1); an inflammatory chemokine elevated in IPF lungs (CXCL7); and a protein associated with epithelial fibrosis deep in the lung (galectin-7). A trend toward reduced levels of surfactant protein D (SP-D), a blood marker of lung epithelial cell health, was also observed at the higher dose; the magnitude was comparable to reductions seen with approved IPF therapies after twelve weeks of treatment, despite this study lasting only fourteen days. The study also provided evidence that LTI-03 may help preserve the lung's own repair cells, a dimension of activity not addressed by currently available treatments.

Brian Windsor, Chief Executive Officer of Rein Therapeutics, commented, “Publication in Nature Communications validates both the quality of our clinical work and the strength of the underlying science. These results, showing that LTI-03 was well-tolerated and produced significant reductions in multiple markers of lung scarring, strengthen the foundation for our ongoing Phase 2 RENEW trial. We remain focused on execution and believe these published data give investors and the scientific community greater confidence in what we are building."

Cory Hogaboam, Chief Scientific Officer of Rein Therapeutics, added, "LTI-03 simultaneously reduced five separate markers of fibrosis, inflammation, and epithelial damage after only fourteen days of treatment. This breadth of activity reflects LTI-03's design as a caveolin-1 mimetic, a molecule that effectively targets a master regulator of multiple scarring pathways. These findings directly support the scientific rationale of our RENEW Phase 2 program."

About the RENEW Phase 2 Trial
Rein’s RENEW trial is a randomized, placebo-controlled Phase 2 clinical study designed to evaluate the safety, tolerability, and efficacy of LTI-03 in patients with idiopathic pulmonary fibrosis.

The study is expected to enroll approximately 120 patients across multiple countries. Patients will be randomized to receive one of two dose levels of LTI-03 or placebo. The major efficacy endpoint is the change from baseline in forced vital capacity (FVC), a key measure of lung function.

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 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.

Cautionary Note Regarding Forward-Looking Statements
This press release may contain forward-looking statements of Rein Therapeutics, Inc. (“Rein”, the “Company”, “we”, “our” or “us”) within the meaning of the Private Securities Litigation Reform Act of 1995, including statements with respect to expectations for the Company’s LTI-03 and LTI-01 product candidates and the closing of the offering. We use words such as “anticipate,” “believe,” “estimate,” “expect,” “hope,” “intend,” “may,” “plan,” “predict,” “project,” “target,” “potential,” “would,” “can,” “could,” “should,” “continue,” and other words and terms of similar meaning to help identify forward-looking statements, although not all forward-looking statements contain these identifying words. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: (i) the risk that the Company may not be able to successfully continue its Phase 2 clinical trials of LTI-03; (ii) the data derived from our Phase 2 clinical trials of LTI-03 may not support or validate our expectations concerning the potential benefits of LTI-03; (iii) success in early phases of pre-clinical and clinical trials do not ensure later clinical trials will be successful; and (iv) those other risks disclosed in the “Risk Factors” section of the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 filed with the SEC on March 26, 2026, and in subsequent filings that the Company makes with the SEC. These forward-looking statements should not be relied upon as representing the Company’s views as of any date after the date of this press release, and the Company expressly disclaims any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

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