Bellerophon announced that their phase 3 clinical trial using portable nitric oxide in patients with PAH has been stopped. The trial was stopped early after an analysis of data gathered so far showed no evidence of efficacy (the inhaled medication was not effective). There did not appear to be a safety problem.
This clinical trial was exciting as very low nitric oxide levels in the pulmonary arteries of PAH was one of the first observations and has served as a foundation for our understanding of PAH. The robust success of clinical trials in PAH over the past 15 years has created very high expectations for drug developers. However, this recent failure reminds us that the development of successful medications is complex and even outstanding science and encouraging phase 2 trials do not ensure that the medication will be successful in phase 3.
Does this mean that nitric oxide will not be developed for outpatients with PAH?
The answer is that for the near term, nitric oxide is not likely to have a role in PAH therapy outside of the hospital. What about patients with brisk response to nitric oxide? Unfortunately, I don’t see a path forward even in patients who might benefit the most.
Bellerophon has announced that they plan to continue their clinical trial of inhaled nitric oxide in patients with COPD and pulmonary fibrosis.
We should not be overly disheartened that inhaled nitric oxide did not turn out to be a success. The path to even better treatments (an someday a cure) for our PAH patients will undoubtedly have successes and failures. We need to focus on the long game and remain enthusiastic in our support of clinical research as the best opportunity to find even more effective treatments for PAH.