Publications

Cardiomyocyte T tubules are important for regulating ion flux. Bridging integrator 1 (BIN1) is a T-tubule protein associated with calcium channel trafficking that is downregulated in failing hearts. Here we find that cardiac T tubules normally contain dense protective inner membrane folds that are formed by a cardiac isoform of BIN1. In mice with cardiac Bin1 deletion, T-tubule folding is decreased, which does not change overall cardiomyocyte morphology but leads to free diffusion of local extracellular calcium and potassium ions, prolonging action-potential duration and increasing susceptibility to ventricular arrhythmias. We also found that T-tubule inner folds are rescued by expression of the BIN1 isoform BIN1+13+17, which promotes N-WASP-dependent actin polymerization to stabilize the T-tubule membrane at cardiac Z discs. BIN1+13+17 recruits actin to fold the T-tubule membrane, creating a 'fuzzy space' that protectively restricts ion flux. When the amount of the BIN1+13+17 isoform is decreased, as occurs in acquired cardiomyopathy, T-tubule morphology is altered, and arrhythmia can result.

BACKGROUND

Acetylcysteine has been suggested as a beneficial treatment for idiopathic pulmonary fibrosis, although data from placebo-controlled studies are lacking.

METHODS

In our initial double-blind, placebo-controlled trial, we randomly assigned patients who had idiopathic pulmonary fibrosis with mild-to-moderate impairment in pulmonary function to receive a three-drug regimen of prednisone, azathioprine, and acetylcysteine; acetylcysteine alone; or placebo. The study was interrupted owing to safety concerns associated with the three-drug regimen. The trial continued as a two-group study (acetylcysteine vs. placebo) without other changes; 133 and 131 patients were enrolled in the acetylcysteine and placebo groups, respectively. The primary outcome was the change in forced vital capacity (FVC) over a 60-week period.

RESULTS

At 60 weeks, there was no significant difference in the change in FVC between the acetylcysteine group and the placebo group (-0.18 liters and -0.19 liters, respectively; P=0.77). In addition, there were no significant differences between the acetylcysteine group and the placebo group in the rates of death (4.9% vs. 2.5%, P=0.30 by the log-rank test) or acute exacerbation (2.3% in each group, P>0.99).

CONCLUSIONS

As compared with placebo, acetylcysteine offered no significant benefit with respect to the preservation of FVC in patients with idiopathic pulmonary fibrosis with mild-to-moderate impairment in lung function. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov number, NCT00650091.).

BACKGROUND AND OBJECTIVE

Pirfenidone is an oral antifibrotic agent that is approved in several countries for the treatment of idiopathic pulmonary fibrosis (IPF). We performed a comprehensive analysis of safety across four clinical trials evaluating pirfenidone in patients with IPF.

METHODS

All patients receiving pirfenidone 2403 mg/day in the Phase 3 CAPACITY studies (Studies 004 and 006) and all patients receiving at least one dose of pirfenidone in one of two ongoing open-label studies in patients with IPF (Studies 002 and 012) were selected for inclusion. Safety outcomes were evaluated from baseline until 28 days after the last dose of study drug.

RESULTS

A total of 789 patients were included in the analysis. The median duration of exposure to pirfenidone was 2.6 years (range, 1 week-7.7 years), and the cumulative total exposure was 2059 person exposure years (PEY). Gastrointestinal and skin-related events were the most commonly reported adverse events; these were almost always mild to moderate in severity, and rarely led to treatment discontinuation. Elevations (>3× upper limit of normal) in alanine aminotransferase (ALT) or aspartate aminotransferase (AST) occurred in 21/789 (2.7%) patients; the adjusted incidence of AST/ALT elevations was 1.7 per 100 PEY.

CONCLUSIONS

This comprehensive analysis of safety in a large cohort of IPF patients receiving pirfenidone for a total of 2059 PEY demonstrates that long-term treatment with pirfenidone is safe and generally well tolerated.

BACKGROUND

In two of three phase 3 trials, pirfenidone, an oral antifibrotic therapy, reduced disease progression, as measured by the decline in forced vital capacity (FVC) or vital capacity, in patients with idiopathic pulmonary fibrosis; in the third trial, this end point was not achieved. We sought to confirm the beneficial effect of pirfenidone on disease progression in such patients.

METHODS

In this phase 3 study, we randomly assigned 555 patients with idiopathic pulmonary fibrosis to receive either oral pirfenidone (2403 mg per day) or placebo for 52 weeks. The primary end point was the change in FVC or death at week 52. Secondary end points were the 6-minute walk distance, progression-free survival, dyspnea, and death from any cause or from idiopathic pulmonary fibrosis.

RESULTS

In the pirfenidone group, as compared with the placebo group, there was a relative reduction of 47.9% in the proportion of patients who had an absolute decline of 10 percentage points or more in the percentage of the predicted FVC or who died; there was also a relative increase of 132.5% in the proportion of patients with no decline in FVC (P<0.001). Pirfenidone reduced the decline in the 6-minute walk distance (P=0.04) and improved progression-free survival (P<0.001). There was no significant between-group difference in dyspnea scores (P=0.16) or in rates of death from any cause (P=0.10) or from idiopathic pulmonary fibrosis (P=0.23). However, in a prespecified pooled analysis incorporating results from two previous phase 3 trials, the between-group difference favoring pirfenidone was significant for death from any cause (P=0.01) and from idiopathic pulmonary fibrosis (P=0.006). Gastrointestinal and skin-related adverse events were more common in the pirfenidone group than in the placebo group but rarely led to treatment discontinuation.

CONCLUSIONS

Pirfenidone, as compared with placebo, reduced disease progression, as reflected by lung function, exercise tolerance, and progression-free survival, in patients with idiopathic pulmonary fibrosis. Treatment was associated with an acceptable side-effect profile and fewer deaths. (Funded by InterMune; ASCEND ClinicalTrials.gov number, NCT01366209.).