Therapeutic Clinical Trial of Oral Pirfenidone for the Pulmonary Fibrosis of Hermansky-Pudlak Syndrome

Hermansky-Pudlak Syndrome (HPS) is a rare autosomal recessive disease consisting of oculocutaneous albinism and a platelet storage pool defect. The most serious complication of this disorder, which is common in Puerto Rico, is pulmonary fibrosis, generally fatal in the fourth or fifth decade. There is no treatment for the pulmonary disease of HPS, which resembles idiopathic pulmonary fibrosis. However, a drug called pirfenidone has antifibrotic effects in animal models of lung fibrosis. Pirfenidone is an IND drug initially provided by Marnac, Inc.; InterMune, Inc., now holds the license. Pirfenidone inhibits cytokine-induced inflammation. Reported side effects include gastrointestinal upset, a photosensitivity rash, and palpitations. Between 1997 and 2001, we performed a randomized, placebo-controlled trial under this protocol that found pirfenidone to be safe and efficacious when analyzed using a repeated measures model. Using a random coefficients model, however, the data were definitive only in the restricted group of subjects whose initial forced vital capacity was greater than 50% of predicted. Because the repeated measures analysis had been chosen a priori as the optimal model, the DSMB stopped the study and directed that all patients receive pirfenidone. (Of the 23 original patients, 3 are still receiving pirfenidone under this protocol.)

Now, to prove efficacy of pirfenidone, we are conducting a block-randomized, placebo-controlled, double-blind trial involving up to 40 HPS patients whose forced vital capacity is 51-85% of predicted. For every patient randomly assigned to the placebo group, two will receive pirfenidone. Patients are largely drawn from the Puerto Rican population and are simultaneously enrolled in clinical protocol 95-HG-193. They are admitted to the NIH Clinical Center for 2-3 day admissions every 4 months. The primary efficacy variable is change in forced vital capacity, determined on every admission. Secondary efficacy variables are also examined. A CT scan of the chest and bone densitometry are performed. After 4 years of patient accrual, 35 patients were enrolled; the original statistical analysis plan (SAP) called for 39 patients to be enrolled within one year. The NHGRI DSMB revised the original SAP to perform an interim data analysis 12 months after 30 patients were enrolled, i.e., in May of 2009. That analysis directed the study to stop due to futility. However, this protocol will continue to provide pirfenidone to the three original protocol patients still enrolled, and to any pirfenidone-treated patients who choose to undergo pulmonary lavage to help us determine the effects of pirfenidone on the cytokine profile of alveolar macrophages. The lavages would require enrollment in a separate protocol. The treatment drug will be stopped immediately for all placebo patients and for pirfenidone patients who do not plan to enroll in the lavage protocol. Pirfenidone treatment will stop just after the lavage is performed on patients who do enroll in the lavage protocol, 04-HG-0211. All patients will be invited to continue to come to the NIH annually under the HPS natural history protocol, 95-HG-0193.