The Unmet Need
WHO Group 1 : Pulmonary Arterial Hypertension (PAH)
The natural history of PAH was documented by the NIH Registry on Primary Pulmonary Hypertension from 1981-1987, when there were no approved treatments for PAH. Five-year survival was only 34%, which is especially alarming since the mean age of patients at diagnosis was 38 ± 15 years. Presently there is no cure for PAH, but there are several treatment options that aim to reduce symptoms, improve the quality of life, and potentially slow disease progression. The only approved drugs that have emerged from clinical trials are pulmonary vasodilators.
Observational studies suggest survival has improved in the modern management era. It is unknown what the actual impact of these drugs is in clinical practice, which are often used in combination, on patient outcomes. However, a reasonable estimate comes from a modern registry in the U.S. as representative of the standard of care utilizing pulmonary vasodilators over the current time period. Five-year survival from initial diagnosis was reported to be 57%, an important improvement, but still unacceptable. Thus, PAH continues to have a serious unmet need.