Inhaled LTI-03 for Idiopathic Pulmonary Fibrosis: A Randomized Dose Escalation Study

In a Phase 1b randomized dose-escalation study, inhaled LTI-03 demonstrated a favorable safety profile and significantly reduced key fibrotic and epithelial biomarkers in patients with idiopathic pulmonary fibrosis, supporting its further evaluation in a Phase 2 trial.

The Gist

The Big Picture: A "Repair Crew" for Scarred Lungs

Imagine your lungs are like a bustling city. In a healthy city, the buildings (lung cells) are strong, and when they get a little scratch, they fix themselves quickly.

But in Idiopathic Pulmonary Fibrosis (IPF), the city is in trouble. The buildings are getting damaged, and instead of fixing themselves, the city's construction crew (fibroblasts) goes into overdrive. They start laying down too much concrete and steel (scar tissue) everywhere. This turns the flexible, sponge-like lungs into stiff, heavy bricks, making it hard to breathe.

Currently, we have a few "traffic controllers" (existing drugs) that can slow down the construction crew, but they can't stop the damage, and they often cause side effects like stomach aches or skin rashes because they travel through the whole body.

Enter LTI-03: Think of this new drug as a specialized "Repair Crew Uniform." Its job is to tell the damaged lung cells, "Hey, don't panic! Put down the concrete and start healing properly."

What Did This Study Do?

This was a Phase 1b study, which is like a "safety and first-look" test. The researchers wanted to see two things:

1. Is this new "uniform" safe to wear?
2. Does it actually get to the construction site and start working?

They tested it on 24 people with IPF. They split them into groups:

• Some got a low dose (5 mg).
• Some got a high dose (10 mg).
• Some got a "sugar pill" (placebo) to compare against.

They used a dry-powder inhaler (like an asthma inhaler) so the medicine goes straight to the lungs, avoiding the stomach and blood. They did this twice a day for 14 days.

The Results: Good News!

1. Safety: The "No Crash" Test

The most important question was: Did it hurt anyone?

• Verdict: No. The drug was very well tolerated.
• The "Cough" Factor: The most common side effect was a little cough. Think of this like a tiny bit of dust getting in your eye when you spray something; it's annoying but usually goes away quickly. It wasn't dangerous, and no one had to quit the study because of it.
• No Systemic Trouble: Because the drug stays in the lungs, it didn't cause the stomach aches or skin rashes common with other lung drugs. It stayed local, like a targeted repair crew rather than a bulldozer driving through the whole city.

2. The "Deep Dive" (Biomarkers)

The researchers didn't just ask patients how they felt; they took tiny samples from deep inside the lungs (using a bronchoscope, which is like a tiny camera and brush) to see what was happening at a microscopic level.

They looked for specific "chemical messengers" that tell the body to build scar tissue.

• The Findings: In the groups taking LTI-03, the levels of these "scar-building messengers" dropped significantly compared to the placebo group.
• The Analogy: Imagine the construction crew was shouting, "Build more concrete!" The LTI-03 seemed to turn down the volume on those shouts. Specifically, it reduced signals like IL-11 and TSLP, which are known to drive the scarring process.

3. The "Blood Test" Mystery

They also checked the patients' blood to see if the drug entered the bloodstream.

• The Result: The drug was undetectable in the blood.
• Why this is good: It means the drug is staying exactly where it's needed (in the lungs) and isn't floating around the rest of the body causing side effects. It's like a delivery driver who drops the package at the front door and leaves immediately, rather than hanging out in the living room.

The One Small Glitch

One person in the low-dose group stopped the drug early because their breathing test (FEV1) dipped slightly. However, the researchers realized later that the rules for stopping weren't actually met (it was a false alarm). This shows the team was being very careful, but ultimately, the drug didn't cause a real problem.

What Does This Mean for the Future?

This study is like a successful pilot test for a new airline route.

• The Plane: LTI-03.
• The Route: Direct delivery to the lungs.
• The Outcome: The plane landed safely, the passengers were comfortable, and the cargo (the medicine) arrived at the destination and started doing its job.

The Bottom Line:
This small study suggests that LTI-03 is safe, easy to take, and shows early signs that it can actually stop the scarring process in the lungs. Because of these promising results, the researchers are now planning a larger, longer study (called RENEW) to see if it can actually help people breathe better and live longer.

It's a hopeful step toward a treatment that targets the root cause of lung scarring rather than just slowing it down.

Technical Summary

1. Problem Statement

Idiopathic Pulmonary Fibrosis (IPF) is a progressive, fatal interstitial lung disease characterized by alveolar epithelial cell (AEC) apoptosis, myofibroblast proliferation, and extracellular matrix (ECM) deposition.

• Current Limitations: Approved anti-fibrotic therapies (nintedanib, pirfenidone, nerandomilast) only slow the rate of forced vital capacity (FVC) decline; they do not halt progression or restore lung function. Furthermore, these drugs often suffer from poor tolerability (gastrointestinal and cutaneous side effects), leading to frequent discontinuation.
• Unmet Need: There is an urgent need for therapies that target the underlying causes of IPF (specifically AEC injury and repair mechanisms) with a more favorable safety profile.
• Mechanistic Gap: Caveolin-1 (Cav-1), a protein critical for lung repair and epithelial health, is downregulated in IPF. While exogenous Caveolin Scaffolding Domain (CSD) peptides have shown efficacy in preclinical models, their delivery has been challenging due to limited aqueous solubility.

2. Methodology

Study Design:

• Type: Phase 1b, randomized, double-blind, placebo-controlled, dose-escalation study.
• Population: 24 participants with IPF (diagnosed within 3 years, FVC ≥40%, DLCO 30–80%, FEV1/FVC ≥0.7). No prior use of anti-fibrotic drugs.
• Intervention: Inhaled LTI-03 (a synthetic 7-amino acid CSD peptide) administered via a dry-powder inhaler (DPI) twice daily (BID) for 14 days.
• Dosing: Two sequential cohorts:
  • Cohort 1: 5 mg/day (2.5 mg BID) vs. Placebo.
  • Cohort 2: 10 mg/day (5 mg BID) vs. Placebo.
  • Randomization: 3:1 ratio (LTI-03:Placebo).
• Endpoints:
  • Primary: Incidence of Treatment-Emergent Adverse Events (TEAEs).
  • Secondary/Exploratory: Pharmacokinetics (PK), Pharmacodynamics (PD) via biomarkers in plasma, peripheral blood mononuclear cells (PBMCs), and deep bronchial brushings (DBB).
• Procedures: Participants underwent bronchoscopy at baseline and Day 14 (2–3 hours post-morning dose) to collect DBB, bronchoalveolar lavage (BAL), and bronchoabsorption samples. Spirometry was performed pre- and post-dose.

3. Key Contributions

• First-in-Human (FIH) Data: This is the first clinical study to evaluate the safety and tolerability of inhaled LTI-03 in IPF patients.
• Novel Delivery System: Demonstrates the feasibility of delivering a hydrophobic CSD peptide via an excipient-free dry-powder inhaler, achieving deep lung deposition without systemic absorption.
• Biomarker Validation: Validates the use of deep bronchial brushing (DBB) to detect localized pharmacodynamic effects of inhaled therapies on fibrotic pathways within the lung microenvironment.
• Mechanistic Proof-of-Concept: Provides early clinical evidence that LTI-03 can modulate specific profibrotic and inflammatory pathways (IL-11, TSLP, COL1A1) in human IPF lungs.

4. Key Results

Safety and Tolerability:

• Completion: All 24 participants completed the study; no discontinuations due to TEAEs.
• Adverse Events: TEAEs occurred in 66.7% (5 mg), 77.8% (10 mg), and 50% (placebo) of participants. Most were Grade 1 (mild).
• Most Common TEAE: Cough (reported by 33.3% of 5 mg, 55.6% of 10 mg, and 33.3% of placebo). Only two Grade 2 cough events occurred (one in each LTI-03 group), both resolving the same day.
• Serious Events: One Grade 2 post-bronchoscopy fever in the 10 mg group (unrelated to study drug). No Grade 3+ TEAEs.
• Physiological Impact: No clinically significant changes in spirometry (FEV1, FVC), vital signs, ECG, or cough severity scores (LCQ/VAS) were observed, indicating no acute airway obstruction or worsening of chronic cough.

Pharmacokinetics (PK):

• Systemic Exposure: LTI-03 was undetectable (below limit of quantification) in plasma at all time points, indicating minimal systemic absorption.
• Local Exposure: LTI-03 was quantifiable in BALF for 5 participants (3 in 5 mg group, 2 in 10 mg group), confirming successful delivery to the lung tissue.

Pharmacodynamics (Biomarkers):

• Deep Bronchial Brushing (DBB) Results: LTI-03 treatment significantly reduced the expression of key profibrotic markers compared to placebo:
  • IL-11 & TSLP: Significantly reduced in both 5 mg and 10 mg groups. (IL-11 is a driver of myofibroblast activation; TSLP is an alarmin promoting fibrosis).
  • COL1A1 (Collagen Type 1 Alpha 1): Significantly reduced in the 10 mg group.
  • CXCL7 & Galectin-7: Significantly reduced in the 10 mg group.
• Plasma/PBMC Results:
  • SP-D (Surfactant Protein D): Showed a 5% reduction in the 10 mg group vs. placebo (trend, p=0.1111), comparable to reductions seen with standard-of-care drugs over longer periods.
  • p-AKT: No significant modulation observed in PBMCs, suggesting the effect is localized to the lung epithelium rather than circulating immune cells.

5. Significance and Conclusion

• Safety Profile: Inhaled LTI-03 demonstrated a favorable safety and tolerability profile with no systemic toxicity, supporting the hypothesis that local delivery minimizes off-target effects common in systemic anti-fibrotics.
• Disease Modifying Potential: The significant reduction in profibrotic biomarkers (IL-11, TSLP, COL1A1) in the lung tissue suggests that LTI-03 effectively engages its target mechanism (Cav-1 restoration) to attenuate fibrotic pathways and support epithelial integrity.
• Future Directions: The positive safety and biomarker data support the progression to a Phase 2 study (RENEW, NCT06968845) with a longer duration and functional endpoints (e.g., FVC decline) to confirm disease modification.
• Limitations: The study was small (n=24) and short (14 days), preventing conclusions on long-term disease progression. However, it successfully established the proof-of-concept for inhaled CSD peptide therapy in IPF.