Paul Noble, MD: Nintedanib was able to achieve FDA approval doing the same conceptual study for every patient group, by measuring the rate of decline in forced vital capacity [FVC] over 1 year. If you look at the totality of the data for pirfenidone for the approval of IPF [idiopathic pulmonary fibrosis], it’s very similar if not stronger than the nintedanib data in some ways. The working hypothesis was that these drugs would probably have a similar impact on other diseases where there’s progressive fibrosis. But the pirfenidone trials didn’t work out as cleanly as the nintedanib trials, so it isn’t a proved scientific benefit that there’s a clear-cut impact on FVC in these other categories in addition to idiopathic pulmonary fibrosis. That’s why the ATS [American Thoracic Society] recommended additional studies.

There are some variations of pirfenidone being developed: an inhaled form as well as a modified form that might have a longer half-life. Because pirfenidone is generic now, there aren’t going to be any industry-sponsored trials looking to see whether pirfenidone is beneficial in other fibrotic lung diseases. From a functional standpoint, most clinicians see these medications as having a similar overall impact.

One interesting aspect of pirfenidone is the additional research opportunities. As I mentioned, pirfenidone is generic, so there isn’t going to be a pharmaceutical company championing that. However, there are some newer approaches with pirfenidone that could be interesting. One of the holy grails and unanswered questions in fibrotic lung disease is whether an inhaled approach can be developed. Could you breathe in through an inhaler once or twice a day? Because the hallmark of idiopathic pulmonary fibrosis and the other fibrotic lung diseases is they affect only the lungs. In other autoimmune diseases, rheumatoid arthritis affects the joint, and scleroderma [affects] the skin and other organs. But could the lung be targeted directly? This is an unknown question. But there’s a company that has an inhaled form of pirfenidone.

One other issue with both pirfenidone and nintedanib is that both medications have significant tolerability issues. A number of patients are unable to tolerate this medication for prolonged periods of time. Because these medications don’t treat the underlying disease, the concept is that you need to take them for life. If there’s a better-tolerated medication that has similar efficacy, that could be of value to patients.

In addition to the inhaled form of pirfenidone, there’s also a chemically modified form that has a longer half-life. Some of the thinking on pirfenidone is that it isn’t a very strong molecule. If a pirfenidone was developed with greater strength, would it potentially give equal or more efficacy? Could these chemically modified forms potentially have a better safety and tolerability profile? It will be interesting over the next few years to see whether these studies are able to be completed and what we can learn about the next generation of pirfenidone therapies.

Transcript edited for clarity.