Published ahead of print on September 27, 2007, doi:10.1164/rccm.200705-732OC
© 2008 American Thoracic Society doi: 10.1164/rccm.200705-732OC
BUILD-1: A Randomized Placebo-controlled Trial of Bosentan in Idiopathic Pulmonary Fibrosis1 University of California, San Francisco, San Francisco, California; 2 Medizinische Klinik I, Klinikum Grosshadern der Universität, Munich, Germany; 3 National Jewish Medical and Research Center, Denver, Colorado; 4 National Heart and Lung Institute, London, United Kingdom; 5 Vanderbilt University Medical Center, Nashville, Tennessee; 6 University of Alabama at Birmingham, Birmingham, Alabama; 7 Klinik Löwenstein, Löwenstein, Germany; 8 Actelion Pharmaceuticals Ltd, Allschwil, Switzerland; and 9 University of Washington, Seattle, Washington Correspondence and requests for reprints should be addressed to Talmadge E. King, Jr., M.D., Professor and Chair, Department of Medicine, UCSF, 505 Parnassus Avenue, Room M994, San Francisco, CA 94110. E-mail: tking{at}medicine.ucsf.edu
Rationale: Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal lung disease lacking effective treatment. Objectives: To determine the effects of bosentan on exercise capacity and time to disease progression in patients with IPF. Methods: In a double-blind, multicenter trial, patients with IPF were randomized to receive oral bosentan 62.5 mg twice daily for 4 weeks, increased to 125 mg twice daily thereafter, or placebo, for 12 months or longer. The primary efficacy endpoint was change from baseline up to Month 12 in exercise capacity, as measured by a modified six-minute-walk test. Secondary endpoints were time to death or disease progression (worsening pulmonary function tests [PFTs] or acute decompensation), change in PFT scores, and quality of life (QOL) assessed using Short-Form 36 and St. George's Respiratory Questionnaire. Measurements and Main Results: A total of 158 patients randomly received bosentan (n = 74) or placebo (n = 84). Bosentan showed no superiority over placebo in six-minute-walk distance (6MWD) up to Month 12, the primary efficacy endpoint. A trend in favor of bosentan was observed in the secondary endpoint of time to death or disease progression (hazard ratio [HR], 0.613; 95% confidence interval [CI], 0.328–1.144; P = 0.119), which was more pronounced in a patient subgroup diagnosed using surgical lung biopsy (post hoc analysis; HR, 0.315; 95% CI, 0.126–0.789; P = 0.009). Changes from baseline up to Month 12 in assessments of dyspnea and QOL favored treatment with bosentan. No unexpected adverse events were reported. Conclusions: Bosentan treatment in patients with IPF did not show superiority over placebo on 6MWD. A trend in delayed time to death or disease progression, and improvement in QOL, was observed with bosentan. The more pronounced treatment effect in patients with biopsy-proven IPF warrants further investigation. Clinical trial registered with www.clinicaltrials.gov (NCT 00071461).
Key Words: endothelin idiopathic pulmonary fibrosis clinical trial six-minute-walk test survival
Idiopathic pulmonary fibrosis (IPF) is a progressive disease that is severely debilitating and negatively affects quality of life (QOL). The predominant symptom is progressive dyspnea, which occurs first on exercise and then at rest. Prognosis is poor; median survival after biopsy-confirmed IPF is less than 3 years (1). Endothelin (ET)-1, a potent, endogenous vasoconstrictor, is implicated in the pathophysiology of pulmonary arterial hypertension (PAH) through proliferation of smooth muscle cells, inflammation, fibrosis, and endothelial dysfunction (2–7). In addition, ET-1 is a profibrotic molecule that can modulate matrix production and turnover, resulting in increased collagen synthesis and decreased interstitial collagenase production (6). Preliminary data suggest that ET-1 plays an important role in the pathogenesis of lung fibrosis. In a rat model of bleomycin-induced pulmonary fibrosis, bosentan, a dual ET receptor antagonist (ETA and ETB), was shown to reduce collagen deposition in the lungs (8). Bosentan has been shown to be an efficacious treatment for PAH, a disease characterized by progressive remodeling of the pulmonary vasculature. Consequently, we hypothesized that bosentan may influence the course of IPF through its antiinflammatory and antifibrotic effects. The BUILD 1 (Bosentan Use in Interstitial Lung Disease) study was designed to evaluate the efficacy, safety, and tolerability of bosentan in patients with IPF. The primary objective was to evaluate the effect of bosentan on exercise capacity (six-minute-walk distance [6MWD]). Secondary objectives included investigation of the effect of bosentan on time to disease progression or death, pulmonary function tests (PFTs), dyspnea, and QOL, as well as determining its safety and tolerability in patients with IPF. Some of the results of this clinical trial have been previously reported in abstract form (9–14).
Patient Population This international, prospective, double-blind, randomized, placebo-controlled, parallel group study enrolled patients with a proven diagnosis of IPF made within the last 3 years before enrollment according to American Thoracic Society/European Respiratory Society consensus guidelines (15, 16). In addition to clinical evaluation, a high-resolution computed tomography (HRCT) scan within the previous 3 months was used to demonstrate a definitive diagnosis of IPF. If the diagnosis could not be confirmed based on the HRCT scan, a surgical lung biopsy (SLB) was mandatory to determine a histopathologic diagnosis of usual interstitial pneumonia (UIP), and thus patient eligibility. Patients were included if their duration of illness was 3 months or more and they had a baseline 6MWD between 150 and 499 m. Women of child-bearing age were required to use a reliable method of contraception.
Patients were excluded if they had interstitial lung disease (ILD) due to conditions other than IPF, severe restrictive lung disease (FVC < 50% predicted [formula reported in Reference 17]; diffusing capacity for carbon monoxide [DLCO], corrected for hemoglobin level < 30% predicted [formula reported in Reference 18]; or RV All patients gave written, informed consent to participate in the study, which was approved by the appropriate independent ethics committees or institutional review boards and conducted in accordance with the principles of the Declaration of Helsinki and local laws and guidelines for good clinical practice.
Study Protocol Patients were assessed at baseline and after 3, 6, 9, and 12 months of therapy (or earlier if they discontinued prematurely), and again at the end of the study. Baseline assessments included physical examination, vital signs, ECG and echocardiography, dyspnea and QOL questionnaires, oxygen saturation by pulse oximetry (SpO2) (Nellcor N-595; Pleasanton, CA), and 6MWD. The 6MWD was measured without supplemental oxygen using a modified six-minute-walk test (6MWT), conducted in accordance with American Thoracic Society guidelines (20), but terminated prematurely if SpO2 fell below 80%. The 6MWD, SpO2, and Borg dyspnea index were reassessed at the 3-, 6-, and 9-month visits and, together with full PFTs and laboratory tests, at Month 12. These assessments were repeated in patients at the end of study.
Outcome Measures
Safety.
Statistical Methods Secondary and exploratory endpoints were summarized descriptively for the all-treated set. Statistical tests of treatment comparison were for exploratory purposes, as no formal hypothesis testing for these comparisons was planned. No correction for multiple testing was performed. Kaplan-Meier estimates of the survivor function at different time points were presented together with the 95% CI calculated using Greenwood's formula. The log-rank test was used to compare treatments for time-to-event distribution. The hazard ratio (HR) of the bosentan group to placebo was calculated together with its 95% CI by means of Cox's modeling using only the treatment as an independent variable. Patients who underwent SLB for diagnosis of IPF were identified as a subpopulation of interest before revealing the treatment allocation. The effect of bosentan in this specific subpopulation was explored in a post hoc analysis.
Baseline Characteristics A total of 154 of the 158 randomized patients were included in the all-treated set (bosentan, n = 71; placebo, n = 83). Treatment groups were generally well matched with regard to demographics and baseline characteristics (Table 1), although the bosentan group had slightly worse baseline FVC, more patients on prednisone and supplemental oxygen, and five patients awaiting lung transplantation compared with none in the placebo group.
In total, 68 and 60% of patients in the bosentan and placebo groups, respectively, had undergone SLB at diagnosis. Patients with biopsy-proven IPF had similar duration of symptoms and lung function at baseline compared with the all-treated set but tended to be younger; biopsy-proven patients had a mean age of 62.4 and 64.1 years in the bosentan and placebo groups, respectively, compared with 65.3 and 65.1 years in the all-treated population.
Patient Disposition
Exposure to Study Medication Exposure to study medication was similar in the two treatment groups, with a mean duration (± SD) of 54.0 ± 24.9 weeks in the bosentan group and 56.1 ± 21.0 weeks in the placebo group. The majority of patients in the bosentan and placebo groups (74.3 and 75.0%, respectively) received at least 48 weeks of treatment.
Efficacy
Disease progression or death. Up to Month 12, the combined incidence of disease progression or death was 22.5% (n = 16) in the bosentan group and 36.1% (n = 30) in the placebo group. This corresponded to a relative risk reduction of 38% (95% CI, –5 to 63%; P = 0.078). A positive trend in favor of bosentan was observed in the secondary efficacy endpoint of time to disease progression or death up to Month 12 (HR, 0.613; 95% CI, 0.328–1.144; P = 0.119; Figure 2). These results were driven by the difference in the worsening of FVC and DLCO, as the number of deaths up to Month 12 in each group of patients on study treatment was the same (n = 3) (i.e., death occurring within 15 d of the end of study treatment). There were three cases of acute decompensation of IPF in the placebo group (3.6%) and one case in the bosentan group (1.4%).
PFTs. There were no differences in the proportion of patients with improved or stable PFT scores, and few patients overall had improved PFT scores (n = 3) (Table 3). Mean absolute changes from baseline in percent-predicted FVC up to Month 12 were –6.4 and –7.7% in the bosentan and placebo groups, respectively. Corresponding changes from baseline in percent-predicted DLCO were –4.3 and –5.8% in the bosentan and placebo groups, respectively. No clinically relevant differences were observed between treatment groups with respect to A-a PO2 or SaO2, providing little evidence to suggest that changes in blood gas parameters were a major contributor to worsening PFTs in either treatment arm.
Dyspnea. Shortness of breath, assessed at the end of the 6MWT using the Borg dyspnea index, was more pronounced in the placebo group compared with the bosentan group up to Month 12 (median treatment effect, –0.5; P = 0.071). Patients' perception of dyspnea assessed with the TDI mirrored these findings. From similar mean BDI scores at baseline, TDI total scores worsened in both treatment groups over time. The TDIs at Month 6 were –0.6 and –1.9 in the bosentan and placebo groups, respectively, and –1.7 and –2.6 in the bosentan and placebo groups, respectively, at Month 12. The worsening of the TDI was significantly smaller for patients treated with bosentan than for patients treated with placebo (P = 0.016) at Month 6, but not at Month 12 (P = 0.292).
QOL. Mean changes from baseline in SGRQ scores showed a similar pattern. Total SGRQ score at baseline in the bosentan group (mean ± SD, 45.7 ± 18.1) was similar to that in the placebo group (mean ± SD, 45.2 ± 19). Up to Month 6, the total score in the bosentan group remained almost unchanged (mean ± SD, 45.0 ± 21.3), whereas it worsened in the placebo group (mean ± SD, 47.8 ± 21.7), representing a mean ± SEM treatment effect of –3.3 ± 2.6 (P = 0.034). Mean treatment differences up to Month 12 continued to favor bosentan but were smaller (data not shown).
Patients with SLB.
In addition, QOL results demonstrated a more pronounced treatment effect in favor of bosentan in the SLB subgroup. For these patients, three domains of the SF-36 health transition score showed a significant treatment effect in favor of bosentan at Month 12: "physical functioning" (P = 0.041), "general health" (P = 0.012), and "role emotional" (P = 0.037). Total SGRQ scores at baseline were similar between the bosentan-treated (mean ± SD, 44.3 ± 18.0) and placebo-treated (mean ± SD, 45.9 ± 16.9) SLB subgroups. Up to Month 6, the mean total SGRQ score in the bosentan-treated subgroup remained similar to baseline (mean ± SD, 43.6 ± 18.2), but worsened in the placebo-treated subgroup (mean ± SD, 49.2 ± 21.3)—a mean ± SEM treatment effect of –7.3 ± 2.8 (P = 0.010) in favor of bosentan. Up to Month 12, the mean total SGRQ scores favored treatment with bosentan (mean ± SD, 46.1 ± 19.9) versus placebo (mean ± SD, 51.1 ± 23.7)—a mean ± SEM treatment effect of –6.6 ± 3.0 (P = 0.058).
Safety SAEs up to end of treatment were mainly respiratory in nature and were slightly less frequent in the bosentan group (34 SAEs in 22 patients, 29.7%) than in the placebo group (44 SAEs in 29 patients, 34.5%). In contrast to the deaths that occurred on study treatment (n = 3 in each group), the total number of deaths at 1 year, including patients who were on or off study medication or had prematurely discontinued study treatment, was eight in the placebo group and five in the bosentan group. The majority of deaths were due to IPF.
The BUILD-1 study was a large, randomized, multinational, double-blind, placebo-controlled trial in a well-defined population of patients with IPF. It is the first randomized trial to investigate the effects of an ET receptor antagonist in IPF. A previous open-label study of the safety of bosentan in 12 patients with IPF reported that long-term bosentan therapy was well tolerated, with AEs similar to those reported in studies with patients with PAH (24). Our study was designed and powered to investigate the effect of bosentan on exercise capacity, by evaluating the change in 6MWD from baseline up to Month 12 using a modified 6MWT. Although bosentan did not show an improvement over placebo with respect to 6MWD, several clinically relevant results in secondary and exploratory endpoints suggest beneficial treatment effects at Months 6 and 12. The most clinically important finding in this study is that treatment with bosentan showed a trend to delayed time to death or disease progression, a predefined secondary endpoint. This treatment effect was significant in the subset of patients who underwent SLB for confirmation of diagnosis. Results for this predefined secondary endpoint in the overall population showed consistent trends in favor of bosentan, both overall and in its PFT components. FVC and DLCO at baseline, as well as changes in these parameters over time, have been shown to be good predictors of survival in patients with IPF (25, 26). Treatment with bosentan was generally well tolerated by patients in this study, with a safety profile consistent with that seen in patients with PAH (27, 28). In this study, 12.2% of bosentan-treated patients discontinued treatment due to abnormal liver function tests, although not all of these patients had an elevation of aminotransferase levels that required treatment discontinuation. All aminotransferase elevations were asymptomatic and resolved or improved without clinical sequelae after dose reduction or treatment discontinuation. In the patients who presented with an atypical HRCT scan, SLB was performed to confirm diagnosis. The subgroup of patients who underwent SLB had a more pronounced treatment effect in regard to the combined incidence of disease progression or death and improvements in QOL. This suggests that treatment with bosentan may be of particular benefit to this subgroup of patients. Results of other secondary efficacy endpoints also provide evidence to suggest beneficial effects with bosentan treatment. Treatment effects with bosentan on both dyspnea (TDI) and QOL (SGRQ) were significant at Month 6, with a favorable trend observed up to Month 12. QOL is known to be impaired in patients with IPF (29, 30), and across all but one domain of the SF-36 QOL instrument, results trended in favor of bosentan, with a significant effect on the role-emotional domain. No other study for IPF to date has shown positive treatment effects on QOL. There are a number of limitations with the BUILD-1 study. The 6WMT has potential confounders and its sensitivity to change can be uncertain (31–34). The 6MWT may not be ideally suited for assessing either disease progression or response to treatment with bosentan in patients with IPF. In addition, use of a modified 6MWT makes comparison with other studies difficult. Second, there were several small imbalances between the treatment groups at baseline to suggest that patients in the bosentan treatment group had more severe disease; baseline PFT values were slightly worse, as was time to desaturation to 88% during the 6MWT (data not shown); more patients in the bosentan group were on oxygen and more were listed for lung transplantation. These differences at baseline may have influenced outcome in the 6MWT. In addition, it is important to note that diagnosis of IPF/UIP is difficult. SLBs were read by local pathologists and not by a core lab. SLBs were read centrally in a post hoc analysis (86 patients) and showed that 64 patients (74%) have a confirmed UIP diagnosis (data not shown). Finally, although a treatment effect in favor of bosentan was observed for the clinically relevant secondary endpoint of time to disease progression or death, the study was not powered to detect a significant difference between treatment groups with respect to this important measurement. In this study, bosentan treatment in patients with IPF did not show superiority over placebo on change in 6MWD from baseline up to Month 12, the primary endpoint. However, bosentan was well tolerated and the observed clinically relevant delay in time to disease progression or death warrants further investigation. A more pronounced effect was observed in patients with SLB-proven IPF. In conclusion, the results of the BUILD-1 study are sufficiently encouraging to be evaluated further in a larger trial. Selection of a primary endpoint of accepted clinical relevance is of paramount importance in any new trial and has already been addressed in the design of the ongoing, larger BUILD-3 morbidity/mortality study in patients with IPF.
The authors thank the investigators involved in this study: Jürgen Behr, Ishaar Bendov, Kevin Brown, Charles Chan, Jean-Francois Cordier, James Dauber, Joao de Andrade, Adaani Frost, Thomas Geiser, Marilyn Glassberg, Jeffrey Golden, Gary Hunninghake, Sanjay Kalra, Lisa Lancaster, Robert Levy, Fernando Martinez, Keith Meyer, Joachim Müller-Quernheim, Paul Noble, Christophe Pison, Charles Poirier, Ganesh Raghu, Milton Rossman, Paola Rottoli, Gerd Stähler, Dominique Valeyre, Athol Wells, Gordon Yung, David Zisman. They also thank Data Safety Monitoring Board members Ariane Herrick, David Rodman, and Jan Tijssen.
Supported by Actelion Pharmaceuticals Ltd, Allschwil, Switzerland Originally Published in Press as DOI: 10.1164/rccm.200705-732OC on September 27, 2007 Conflict of Interest Statement: T.E.K. has served on advisory boards for Actelion (compensation in 2005 = $15,000; 2006 = $11,955; 2007 = $14,913); for InterMune (2005 = $20,000; 2006= $42,000; 2007 = $21,000); for GlaxoSmithKline (2005 = $10,000; 2006 = $15,000); and served as a consultant for Nektar, Alexza, AstraZeneca (AZ); Biogen, Centocor, Fibrogen, Genzyme, Human Genome Sciences, Merck, Chronogen, and CoTherix, and none of these exceeded $10,000 per company per year in any one of the preceding 3 years. J.B. has received fees for speaking and/or organizing education from Actelion Pharmaceutical, ALK Scherax, Altana, AZ, Bayer, Boehringer Ingelheim, GlaxoSmithKline, Merck, Schering, Zambon, Encysive, and ZLB Behring. J.B has received fees for consulting from Actelion Pharmaceutical, Pari, Schering, Zambon, and has received research funds from Actelion, Bayer, Mondobiotech, and Myogene. K.K.B. serves as a consultant to Actelion and received research grants for participation in multiple multicentered clinical trials. R.M.d.B. has been reimbursed by InterMune and Boehringer Ingelheim for serving as steering committee chair; by Actelion (the manufacturer of the drug that is the subject of this manuscript), Centocor, Genzyme, Baxter, Cryptopharma, Cambridge Antibody Technology/AZ, and Novartis for advisory work; and by AZ, InterMune, Actelion, and GlaxoSmithKline for lectures. L.L. served as principal investigator for the Vanderbilt University Medical Center BUILD-1 site. J.A.d.A. received $2,000 for giving a lecture for InterMune in 2005; he has research grants from InterMune in the amount of $234,348 for participation in multicenter clinical trials in the period covering the years 2005–2008. He has research grants from Actelion in the amount of $204,260 for participation in a multicenter clinical trial in the period covering the years 2006–2009. G.S. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. I.L. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. S.R. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. G.R. has received lecture fees from Actelion in 2006 and 2007 ($2,000/yr) and has received industry-sponsored grants for patient-related costs associated with clinical studies sponsored by Actelion, Genzyme, InterMune, and Wyeth. He also serves as a consultant for Gilead, Wyeth, Shionogi; and as a steering committee member for Actelion and Genzyme. Received in original form May 16, 2007; accepted in final form September 27, 2007
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