What is PH-ILD?
Pulmonary Hypertension associated with Interstitial Lung Disease (PH-ILD) is a serious condition in which pulmonary hypertension develops as a complication of interstitial lung disease (ILD).
Interstitial lung diseases are a group of disorders characterized by progressive scarring (fibrosis) of lung tissue, which reduces the lungs’ ability to deliver oxygen to the bloodstream. In some patients, this ongoing lung damage is accompanied by changes in the blood vessels of the lungs, leading to increased pressure in the pulmonary circulation.
When interstitial lung disease and pulmonary hypertension coexist, the result is PH-ILD. A condition associated with increased disease severity and poorer outcomes compared with ILD alone.
How PH-ILD affects the body
PH-ILD affects both the lungs and the pulmonary circulation, making it a particularly complex disease.
Key processes involved include:
- Fibrosis of lung tissue, which stiffens the lungs and impairs oxygen exchange
- Vascular remodeling, where small pulmonary arteries become thickened and narrowed
- Elevated pulmonary blood pressure, increasing strain on the right side of the heart
- Progressive right-heart dysfunction, which may lead to heart failure over time
Because multiple systems are involved, PH-ILD often results in significant limitations in physical activity and daily life.
Symptoms of PH-ILD
Symptoms of PH-ILD may overlap with those of interstitial lung disease and pulmonary hypertension and can include:
- Shortness of breath, particularly during exertion
- Persistent fatigue
- Dizziness or light-headedness
- Chest discomfort
- Swelling of the legs or ankles in more advanced stages
Symptoms often develop gradually, and PH-ILD can be challenging to diagnose early, as signs may initially be attributed to the underlying lung disease.
Why PH-ILD represents a high unmet medical need
Patients with PH-ILD generally experience a more severe disease course than patients with interstitial lung disease alone. The presence of pulmonary hypertension is associated with:
- Reduced exercise capacity
- Faster disease progression
- Higher morbidity and mortality
Treatment options for PH-ILD are limited. Current approaches mainly focus on managing the underlying lung disease and alleviating symptoms, while few therapies directly address the pulmonary vascular component of the condition.
This highlights a significant need for new treatment options that can address the complex biology of PH-ILD.
PH-ILD as a rare disease
PH-ILD is classified as a rare (or orphan) disease in both the US and Europe. Rare disease designation reflects the limited number of affected individuals, but also the high unmet medical need and severity of the condition.
In many regions, therapies developed for rare diseases may qualify for specific regulatory incentives, including market exclusivity following approval, scientific and regulatory support and accelerated review pathways in certain cases.
These frameworks are designed to encourage innovation in areas where treatment options remain limited.