Abstract
BACKGROUND
Cystic fibrosis is a life-limiting disease that is caused by defective or deficient cystic fibrosis transmembrane conductance regulator (CFTR) protein activity. Phe508del is the most common CFTR mutation.
METHODS
We conducted two phase 3, randomized, double-blind, placebo-controlled studies that were designed to assess the effects of lumacaftor (VX-809), a CFTR corrector, in combination with ivacaftor (VX-770), a CFTR potentiator, in patients 12 years of age or older who had cystic fibrosis and were homozygous for the Phe508del CFTR mutation. In both studies, patients were randomly assigned to receive either lumacaftor (600 mg once daily or 400 mg every 12 hours) in combination with ivacaftor (250 mg every 12 hours) or matched placebo for 24 weeks. The primary end point was the absolute change from baseline in the percentage of predicted forced expiratory volume in 1 second (FEV1) at week 24.
RESULTS
A total of 1108 patients underwent randomization and received study drug. The mean baseline FEV1 was 61% of the predicted value. In both studies, there were significant improvements in the primary end point in both lumacaftor–ivacaftor dose groups; the difference between active treatment and placebo with respect to the mean absolute improvement in the percentage of predicted FEV1 ranged from 2.6 to 4.0 percentage points (P<0.001), which corresponded to a mean relative treatment difference of 4.3 to 6.7% (P<0.001). Pooled analyses showed that the rate of pulmonary exacerbations was 30 to 39% lower in the lumacaftor–ivacaftor groups than in the placebo group; the rate of events leading to hospitalization or the use of intravenous antibiotics was lower in the lumacaftor–ivacaftor groups as well. The incidence of adverse events was generally similar in the lumacaftor–ivacaftor and placebo groups. The rate of discontinuation due to an adverse event was 4.2% among patients who received lumacaftor–ivacaftor versus 1.6% among those who received placebo.
CONCLUSIONS
These data show that lumacaftor in combination with ivacaftor provided a benefit for patients with cystic fibrosis homozygous for the Phe508del CFTR mutation. (Funded by Vertex Pharmaceuticals and others; TRAFFIC and TRANSPORT ClinicalTrials.gov numbers, NCT01807923 and NCT01807949.)
Cystic fibrosis is a genetic disease that is associated with high rates of premature death.1–4 It is a multisystem disease that is characterized by pancreatic insufficiency and chronic airway infections associated with loss of lung function, repeated pulmonary exacerbations, and, ultimately, respiratory failure.5
Cystic fibrosis is caused by gene mutations that result in deficient or dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR) protein, an anion channel that is normally present in the epithelial membrane. Phe508del (c.1521_1523delCTT; formerly F508del) is the most common CFTR mutation; approximately 45% of patients with cystic fibrosis are homozygous for this allele.1 Cystic fibrosis is a progressive disease; despite advances in therapies designed to address the symptoms of the disease, the median predicted survival among patients who are homozygous for Phe508del in the United States is 37 years.6 The Phe508del CFTR mutation causes a processing defect that severely reduces protein levels at the epithelial membrane; for the few channels that reach the cell surface, the mutation also disrupts channel opening; together, these effects lead to minimal CFTR chloride transport activity.7–10 One approach to treating cystic fibrosis is to address the underlying cause of the disease by targeting the CFTR protein dysfunction. Restoring chloride transport to p.Phe508del CFTR (formerly F508del CFTR) is therefore thought to require at least two steps: correction of cellular misprocessing to increase the amount of functional mutated CFTR and potentiation to further increase channel opening.
Lumacaftor is an investigational CFTR corrector that has been shown in vitro to correct p.Phe508del CFTR misprocessing and increase the amount of cell surface–localized protein.11 Ivacaftor is an approved CFTR potentiator that increases the open probability of CFTR channels (i.e., the fraction of time that the channels are open) in vitro and improves clinical outcomes in patients 6 years of age or older who have cystic fibrosis and at least one copy of most class III (gating) mutations.12–17 In vitro studies have shown that ivacaftor also potentiates surface-localized p.Phe508del CFTR,18 and the combination of lumacaftor with ivacaftor has been associated with a greater increase in chloride transport than has either agent alone.11
Although neither ivacaftor nor lumacaftor monotherapy has been shown to have meaningful clinical efficacy in patients who are homozygous for the Phe508del CFTR mutation,19,20 a phase 2 study suggested that the combination of lumacaftor and ivacaftor increased CFTR activity to a degree that may be sufficient to improve clinical outcomes in these patients.21 Therefore, two phase 3 trials (TRAFFIC and TRANSPORT) were conducted to evaluate the efficacy and safety of two different doses of lumacaftor in combination with ivacaftor in patients with cystic fibrosis who were homozygous for the Phe508del CFTR mutation.
METHODS
STUDY DESIGN AND OVERSIGHT
The TRAFFIC and TRANSPORT trials were two phase 3, multinational, randomized, double-blind, placebo-controlled, parallel-group studies in which lumacaftor (VX-809, Vertex Pharmaceuticals) was orally administered in combination with ivacaftor (VX-770, Vertex Pharmaceuticals) for 24 weeks; the studies were conducted from April 2013 through April 2014. The study design and methods of data analysis were identical for the two studies, with the exception of the inclusion of ambulatory electrocardiography (TRAFFIC only) and adolescent pharmacokinetic assessments (TRANSPORT only) for a subgroup of patients. The studies were designed to evaluate the efficacy of lumacaftor–ivacaftor in patients with cystic fibrosis who were homozygous for the Phe508del CFTR mutation; the evaluation of safety was a secondary objective. The protocols (available with the full text of this article at NEJM.org) were reviewed and approved by an ethics committee at each of the 187 participating centers; all patients provided written informed consent.
Patients were randomly assigned (in a 1:1:1 ratio) to one of three study groups (Fig. S1 in the Supplementary Appendix, available at NEJM.org): 600 mg of lumacaftor once daily in combination with 250 mg of ivacaftor every 12 hours (LUM [600 mg/day]–IVA), 400 mg of lumacaftor every 12 hours in combination with 250 mg of ivacaftor every 12 hours (LUM [400 mg every 12 hr]–IVA), or lumacaftor-matched placebo every 12 hours in combination with ivacaftor-matched placebo every 12 hours. All regimens were given for 24 weeks. Randomization was stratified according to age (<18 years vs. ≥18 years), sex, and pulmonary function (percentage of predicted forced expiratory volume in 1 second [FEV1] at screening, <70 vs. ≥70).
The sponsor of the studies (Vertex Pharmaceuticals) designed the protocol in collaboration with the authors. Site investigators collected the data, which were analyzed by the sponsor. All the authors had full access to the study data after the study periods were complete and the data were unblinded. The authors vouch for the accuracy and completeness of the data and for the fidelity of this report to the study protocols, which are available at NEJM.org.
STUDY PARTICIPANTS
Eligibility criteria included a confirmed diagnosis of cystic fibrosis, homozygosity for the Phe-508del CFTR mutation, an age of 12 years or older, a percentage of predicted FEV1 at the time of screening that was 40 to 90% of the predicted normal values,22,23 and stable cystic fibrosis disease. Between the screening and baseline visits (≤4 weeks), fluctuation in FEV1 occurred in some cases and was documented; 81 patients had an FEV1 that fell to below 40% of the predicted value at baseline. Patients continued to take their prestudy medications.
STUDY ASSESSMENTS
All assessments were prespecified in the study protocols and statistical analysis plans unless otherwise noted. The primary end point was the absolute change from baseline at week 24 in the percentage of predicted FEV1, calculated by averaging the mean absolute change at week 16 and the mean absolute change at week 24; this approach was used because we anticipated that it would reduce variability, as compared with using the point estimate at week 24 alone. Key secondary end points included the relative change from baseline in the percentage of predicted FEV1 (calculated by averaging the mean values for weeks 16 and 24), the absolute change from baseline at week 24 in body-mass index (BMI), the absolute change from baseline at week 24 in the patient-reported Cystic Fibrosis Questionnaire–Revised (CFQ-R) respiratory domain score (scores range from 0 to 100, with higher scores indicating a higher patient-reported quality of life with regard to respiratory status),24 the percentage of patients with a relative increase from baseline of 5% or higher in the percentage of predicted FEV1 (calculated by averaging the mean values for weeks 16 and 24), and the number of pulmonary exacerbations through week 24. The time to the first pulmonary exacerbation was assessed, as was the absolute change in body weight. The safety of the study regimens was also evaluated. Subgroup analyses and additional assessments of exacerbation, including assessments of the numbers of patients requiring hospitalization and those requiring treatment with intravenous antibiotics, were also performed.
STATISTICAL ANALYSES
All patients who underwent randomization and received at least one dose of study drug were included in the efficacy analysis, in which patients were analyzed as part of the study group to which they were randomly assigned (full analysis set). In the primary analysis, we evaluated the treatment difference in the percentage of predicted FEV1 at week 24, which was assessed as the difference between the treatment groups and the placebo group in the primary end point.
The safety set included all patients who received any amount of study drug; data were analyzed according to the patients’ actual study group (regardless of the group to which they had been randomly assigned). The reported adverse events are those that either developed or increased in severity at or after the time patients received the initial dose of study drug, up to 28 days after receipt of the last dose. Additional details regarding the statistical analysis, including the hierarchical testing procedure for the multiple end points and the criteria for the assessment of statistical significance, are provided in the Supplementary Appendix.
RESULTS
PARTICIPANTS
Of the 1122 patients who underwent randomization (559 in the TRAFFIC study and 563 in the TRANSPORT study), 1108 received at least one dose of study drug or placebo (Fig. S2 in the Supplementary Appendix). The baseline demographic and other characteristics were well balanced across study groups (Table 1, and Table S1 in the Supplementary Appendix). The mean baseline FEV1 was 61% of the predicted value. At baseline, a high percentage of patients reported maintenance use of multiple pulmonary, nutritional, and other cystic fibrosis therapies. The majority of patients completed their assigned study regimens: 348 patients in the LUM (600 mg/day)–IVA group (94.6%), 344 patients in the LUM (400 mg every 12 hr)–IVA group (93.2%), and 362 patients in the placebo group (97.6%).
Table 1.
Baseline Characteristics and Demographic Data.*
| Characteristic | Placebo (N = 371) | LUM (600 mg/day)–IVA (N = 368) | LUM (400 mg every 12 hr)–IVA (N = 369) |
|---|---|---|---|
| Female sex — no. (%) | 181 (48.8) | 182 (49.5) | 182 (49.3) |
| Mean age (range) — yr | 25.4 (12–64) | 24.5 (12–54) | 25.3 (12–57) |
| Age group — no. (%) | |||
| 12 to <18 yr | 96 (25.9) | 96 (26.1) | 98 (26.6) |
| ≥18 yr | 275 (74.1) | 272 (73.9) | 271 (73.4) |
| Percentage of predicted FEV1 at baseline | |||
| Mean (range) | 60.4 (33.9–99.8) | 60.8 (31.1–92.3) | 60.5 (31.3–96.5) |
| Subgroup — no. (%) | |||
| <40 | 28 (7.5) | 24 (6.5) | 29 (7.9) |
| ≥40 to <70 | 238 (64.2) | 241 (65.5) | 233 (63.1) |
| ≥70 to ≤90 | 97 (26.1) | 98 (26.6) | 100 (27.1) |
| >90 | 3 (0.8) | 3 (0.8) | 3 (0.8) |
| Mean BMI (range)† | 21.0 (14.1–32.2) | 21.0 (14.2–35.1) | 21.5 (14.6–31.4) |
| Maintenance use of pulmonary or respiratory cystic fibrosis therapy at baseline — no. (%) | |||
| Bronchodilators | 342 (92.2) | 342 (92.9) | 344 (93.2) |
| Dornase alfa | 281 (75.7) | 289 (78.5) | 273 (74.0) |
| Inhaled antibiotics | 258 (69.5) | 232 (63.0) | 225 (61.0) |
| Azithromycin | 233 (62.8) | 233 (63.3) | 215 (58.3) |
| Inhaled hypertonic saline | 220 (59.3) | 197 (53.5) | 227 (61.5) |
| Inhaled glucocorticoids | 220 (59.3) | 213 (57.9) | 212 (57.5) |
The LUM (600 mg/day)–IVA group received 600 mg of lumacaftor (LUM) once daily in combination with 250 mg of ivacaftor (IVA) every 12 hours; the LUM (400 mg every 12 hr)–IVA group received 400 mg of lumacaftor every 12 hours in combination with 250 mg of ivacaftor every 12 hours. FEV1 denotes forced expiratory volume in 1 second.
The body-mass index (BMI) is the weight in kilograms divided by the square of the height in meters.
CLINICAL EFFICACY
In both studies, FEV1 improvements were observed as early as day 15 and were sustained through 24 weeks in both lumacaftor–ivacaftor dose groups (Fig. 1A, and Fig. S3 and S4 in the Supplementary Appendix). The difference between lumacaftor–ivacaftor and placebo with respect to the mean absolute change in the percentage of predicted FEV1 from baseline at week 24 was significant in all dose groups and ranged from 2.6 to 4.0 percentage points (P<0.001 for all comparisons) (Table 2). The difference between lumacaftor–ivacaftor and placebo with respect to the mean relative change in FEV1 was also significant and ranged from 4.3 to 6.7% (P<0.001 for all groups) (Table 2). In each study, the percentage of patients who had a relative improvement in the percentage of predicted FEV1 of 5% or higher was greater in the lumacaftor–ivacaftor groups than in the placebo group (P<0.001 to P = 0.002 for the odds ratio) but was not significant in the testing hierarchy (Table 2, and Table S2 in the Supplementary Appendix). In the pooled analysis, approximately twice as many patients in the lumacaftor–ivacaftor groups as in the placebo group had a relative improvement in the percentage of predicted FEV1 of 5% or higher (39 to 46% vs. 22%) and 10% or higher (24 to 27% vs. 13%) (Table 2, and Table S2 and Fig. S5 in the Supplementary Appendix). The mean absolute change in the percentage of predicted FEV1 was also assessed in a variety of subgroups (e.g., subgroups defined according to various baseline characteristics and concomitant medications); the improvement in the percentage of predicted FEV1 in the lumacaftor–ivacaftor groups versus the placebo group was consistent across all subgroups (Fig. 1B, and Fig. S6 in the Supplementary Appendix). Additional details are provided in the Supplementary Appendix.
Figure 1. Absolute Changes from Baseline in the Percent-age of Predicted Forced Expiratory Volume in 1 Second (FEV1) According to Study Group.
The LUM (600 mg/day)–IVA group received 600 mg of lumacaftor (LUM) once daily in combination with 250 mg of ivacaftor (IVA) every 12 hours; the LUM (400 mg every 12 hr)–IVA group received 400 mg of lumacaftor every 12 hours in combination with 250 mg of ivacaftor every 12 hours. Panel A shows the mean absolute change in the percentage of predicted FEV1 over time in each study group; the difference between each active-treatment group and the placebo group at each time point was significant (P<0.025). Panel B shows subgroup analyses of the differences between the active treatment and placebo in the absolute change from baseline in the percentage of predicted FEV1 at week 24. Data in both panels are least-squares means; I bars indicate 95% confidence intervals. The results represent pooled data from the TRAFFIC and TRANSPORT studies.
Table 2.
Efficacy Results at Week 24.*
| Result | TRAFFIC | TRANSPORT | Pooled | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Placebo (N = 184) | LUM (600 mg/ day)–IVA (N = 183) | LUM (400 mg every 12 hr)–IVA (N = 182) | Placebo (N = 187) | LUM (600 mg/ day)–IVA (N = 185) | LUM (400 mg every 12 hr)–IVA (N = 187) | Placebo (N = 371) | LUM (600 mg/ day)–IVA (N = 368) | LUM (400 mg every 12 hr)–IVA (N = 369) | |
| Change in percentage of predicted FEV1 from baseline† | |||||||||
|
| |||||||||
| Difference vs. placebo in the absolute change — percentage points | |||||||||
|
| |||||||||
| Mean (95% CI) | — | 4.0 (2.6 to 5.4)‡ | 2.6 (1.2 to 4.0)‡ | — | 2.6 (1.2 to 4.1)‡ | 3.0 (1.6 to 4.4)‡ | — | 3.3 (2.3 to 4.3)‡ | 2.8 (1.8 to 3.8)‡ |
|
| |||||||||
| P value | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | |||
|
| |||||||||
| Difference vs. placebo in the relative change — % | |||||||||
|
| |||||||||
| Mean (95% CI) | — | 6.7 (4.3 to 9.2)‡ | 4.3 (1.9 to 6.8)‡ | — | 4.4 (1.9 to 7.0)‡ | 5.3 (2.7 to 7.8)‡ | — | 5.6 (3.8 to 7.3)‡ | 4.8 (3.0 to 6.6)‡ |
|
| |||||||||
| P value | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | <0.001 | |||
|
| |||||||||
| Difference vs. placebo in absolute change from baseline in BMI | |||||||||
|
| |||||||||
| Mean (95% CI) | — | 0.16 (−0.04 to 0.35) | 0.13 (−0.07 to 0.32) | — | 0.41 (0.23 to 0.59)‡ | 0.36 (0.17 to 0.54)‡ | — | 0.28 (0.15 to 0.41)‡ | 0.24 (0.11 to 0.37)‡ |
|
| |||||||||
| P value | 0.11 | 0.19 | <0.001 | <0.001 | <0.001 | <0.001 | |||
|
| |||||||||
| Difference vs. placebo in absolute change from baseline in CFQ-R respiratory domain | |||||||||
|
| |||||||||
| Mean (95% CI) — points | — | 3.9 (0.7 to 7.1) | 1.5 (−1.7 to 4.7) | — | 2.2 (−0.9 to 5.3) | 2.9 (−0.3 to 6.0) | — | 3.1 (0.8 to 5.3)‡ | 2.2 (0.0 to 4.5) |
|
| |||||||||
| P value | 0.02 | 0.36 | 0.17 | 0.07 | 0.007 | 0.05 | |||
|
| |||||||||
| Odds ratio for a relative increase of ≥5% from baseline in the percentage of predicted FEV1 | |||||||||
|
| |||||||||
| Odds ratio (95% CI) | — | 2.9 (1.9 to 4.6) | 2.1 (1.3 to 3.3) | — | 3.0 (1.9 to 4.6) | 2.4 (1.5 to 3.7) | — | 2.9 (2.1 to 4.0)‡ | 2.2 (1.6 to 3.1)‡ |
|
| |||||||||
| P value | <0.001 | 0.002 | <0.001 | <0.001 | <0.001 | <0.001 | |||
|
| |||||||||
| Pulmonary exacerbations§ | |||||||||
|
| |||||||||
| Events — no. (rate per 48 wk) | 112 (1.07) | 79 (0.77) | 73 (0.71) | 139 (1.18) | 94 (0.82) | 79 (0.67) | 251 (1.14) | 173 (0.80) | 152 (0.70) |
|
| |||||||||
| Rate ratio (95% CI) | — | 0.72 (0.52 to 1.00) | 0.66 (0.47 to 0.93) | — | 0.69 (0.52 to 0.92) | 0.57 (0.42 to 0.76) | — | 0.70 (0.56 to 0.87)‡ | 0.61 (0.49 to 0.76)‡ |
|
| |||||||||
| P value for the rate ratio | 0.05 | 0.02 | 0.01 | <0.001 | 0.001 | <0.001 | |||
Reported means are least-squares means. For individual studies, within each active-treatment group and between the active-treatment groups and the placebo group, a hierarchical testing procedure was performed to control for multiplicity across primary and key secondary end points; P≤0.0250 in the current test and all previous tests was required to claim significance in the hierarchy. CFQ-R denotes Cystic Fibrosis Questionnaire–Revised.
Changes in the percentage of predicted FEV1 are calculated by averaging the means at weeks 16 and 24.
The difference versus placebo was significant.
The number of pulmonary exacerbations was reported through week 24 and is expressed as a rate over 48 weeks.
Clinically meaningful reductions in the rates of protocol-defined pulmonary exacerbations were seen in both lumacaftor–ivacaftor dose groups. The rate ratio (lumacaftor–ivacaftor vs. placebo) ranged from 0.57 to 0.72 (P<0.001 to P = 0.05; none of the rate ratios were considered significant in the testing hierarchy) (Table 2, and Table S2 in the Supplementary Appendix). In the pooled analysis, the rate of exacerbations was significantly lower in both lumacaftor–ivacaftor dose groups than in the placebo group: 30% lower in the LUM (600 mg/day)–IVA group and 39% lower in the LUM (400 mg every 12 hr)–IVA group (P = 0.001 and P<0.001, respectively) (Table 2, and Table S2 in the Supplementary Appendix). Through week 24, the proportion of patients who remained free from exacerbations in the pooled analysis was significantly higher in both lumacaftor–ivacaftor groups than in the placebo group, and the risk of having an exacerbation was significantly lower in the lumacaftor–ivacaftor groups (Fig. 2A and Table 2). Additional analyses revealed significant reductions with lumacaftor–ivacaftor therapy in the number of exacerbations leading to hospitalizations and those necessitating the administration of intravenous antibiotics (Fig. 2B).
Figure 2. Pulmonary Exacerbations.
The time to first pulmonary exacerbation and number of pulmonary exacerbations leading to hospitalization or treatment with intravenous antibiotics are shown. In Panel B, the number of pulmonary exacerbations observed through week 24 is expressed as a rate over 48 weeks. The results represent pooled data from the TRAFFIC and TRANSPORT studies.
Over the course of the 24-week period, the mean BMI (the weight in kilograms divided by the square of the height in meters) increased steadily in both lumacaftor–ivacaftor dose groups (Fig. S7 in the Supplementary Appendix). In the analysis of the individual trials, the difference between lumacaftor–ivacaftor and placebo with respect to the absolute change in BMI was significant for both dose groups in the TRANSPORT study but for neither dose group in the TRAFFIC study (Table 2). In the pooled analysis at week 24, the treatment difference versus placebo with respect to the absolute change in BMI was 0.24 to 0.28 (P<0.001) (Table 2, and Table S2 and Fig. S7 in the Supplementary Appendix); this represents an improvement of approximately 1% with lumacaftor–ivacaftor. Across the lumacaftor–ivacaftor dose groups in TRAFFIC and TRANSPORT, the least-squares mean change from baseline in body weight at week 24 ranged from 1.23 to 1.57 kg.
The CFQ-R is a cystic fibrosis–specific instrument that is designed to evaluate patient-reported assessments of various health-related measures. In both lumacaftor–ivacaftor dose groups, there were improvements in the within-group CFQ-R respiratory domain score; the treatment difference versus placebo was nominally significant (on the basis of the testing hierarchy) in the analysis of the individual trials only for the LUM (600 mg/day)–IVA group in the TRAFFIC study; the treatment difference reached significance in the LUM (600 mg/day)–IVA group in the pooled analysis (Table 2, and Fig. S8 in the Supplementary Appendix).
SAFETY
Overall, the proportion of patients reporting adverse events was similar across the lumacaftor–ivacaftor groups and the placebo group (Table 3). Pooled across the studies, serious adverse events were reported in 28.6% of the patients in the placebo group and in 17.3 to 22.8% of the patients in the lumacaftor–ivacaftor groups. In all the groups, infective pulmonary exacerbation was the most common serious adverse event (occurring in 24.1% of the patients in the placebo group and in 13.0% of those in the pooled lumacaftor–ivacaftor groups). The proportion of patients who discontinued the study regimen because of an adverse event was higher in the lumacaftor–ivacaftor groups than in the placebo group (4.2% [31 of 738 patients] vs. 1.6% [6 of 370 patients]). Among the patients receiving lumacaftor–ivacaftor, the adverse events that led to discontinuation of the study regimen in two or more patients were elevation of the creatine kinase level (4 patients), hemoptysis (3), bronchospasm (2), dyspnea (2), pulmonary exacerbation (2), and rash (2). No deaths were reported.
Table 3.
Adverse Events Associated with the Study Regimens.*
| Event | Placebo (N = 370) | LUM (600 mg/day)–IVA (N = 369) | LUM (400 mg every 12 hr)–IVA (N = 369) |
|---|---|---|---|
| number of patients (percent) | |||
| Any adverse event reported | 355 (95.9) | 356 (96.5) | 351 (95.1) |
|
| |||
| Discontinuation of the study regimen because of an adverse event | 6 (1.6) | 14 (3.8) | 17 (4.6) |
|
| |||
| At least one serious adverse event | 106 (28.6) | 84 (22.8) | 64 (17.3) |
|
| |||
| Most common adverse events† | |||
|
| |||
| Infective pulmonary exacerbation of cystic fibrosis | 182 (49.2) | 145 (39.3) | 132 (35.8) |
|
| |||
| Cough | 148 (40.0) | 121 (32.8) | 104 (28.2) |
|
| |||
| Headache | 58 (15.7) | 58 (15.7) | 58 (15.7) |
|
| |||
| Increase in sputum production | 70 (18.9) | 55 (14.9) | 54 (14.6) |
|
| |||
| Dyspnea | 29 (7.8) | 55 (14.9) | 48 (13.0) |
|
| |||
| Hemoptysis | 50 (13.5) | 52 (14.1) | 50 (13.6) |
|
| |||
| Diarrhea | 31 (8.4) | 36 (9.8) | 45 (12.2) |
|
| |||
| Nausea | 28 (7.6) | 29 (7.9) | 46 (12.5) |
|
| |||
| Abnormal respiration (chest tightness) | 22 (5.9) | 40 (10.8) | 32 (8.7) |
|
| |||
| Nasopharyngitis | 40 (10.8) | 23 (6.2) | 48 (13.0) |
|
| |||
| Oropharyngeal pain | 30 (8.1) | 44 (11.9) | 24 (6.5) |
|
| |||
| Upper respiratory tract infection | 20 (5.4) | 24 (6.5) | 37 (10.0) |
|
| |||
| Nasal congestion | 44 (11.9) | 33 (8.9) | 24 (6.5) |
|
| |||
| Serious adverse events occurring in at least 3 patients in any treatment group | |||
|
| |||
| Infective pulmonary exacerbation of cystic fibrosis | 89 (24.1) | 55 (14.9) | 41 (11.1) |
|
| |||
| Hemoptysis | 3 (0.8) | 4 (1.1) | 5 (1.4) |
|
| |||
| Distal intestinal obstruction syndrome | 5 (1.4) | 2 (0.5) | 2 (0.5) |
The reported adverse events are those that either developed or increased in severity at or after the time patients received the initial dose of study drug (placebo or active agent), up to 28 days after receipt of the last dose.
The most common adverse events were defined as those that occurred in at least 10% of patients in any treatment group.
The adverse events reported more frequently in the lumacaftor–ivacaftor groups were generally respiratory in nature. The majority were of mild-to-moderate severity and included dyspnea and chest tightness (Table 3, and Table S3 in the Supplementary Appendix). Two patients in the placebo group (one with dyspnea and one with chest discomfort) and four patients in the LUM (600 mg/day)–IVA group (two with dyspnea and two with bronchospasm) had adverse events of respiratory symptoms or reactive airways that were severe. In patients who had respiratory-symptom adverse events within 1 to 2 days after the initiation of therapy and who did not discontinue the study regimen, the events generally resolved within the first 2 to 3 weeks of therapy. Beyond the first week of therapy, the incidence of respiratory events was similar in the lumacaftor–ivacaftor and placebo groups. In addition, the pattern of adverse events according to the severity of lung disease at baseline was generally similar across the groups.
Elevations in levels of alanine or aspartate aminotransferase to more than 3 times the upper limit of the normal range were observed in 5.1% of the patients in the placebo group and in 5.2% of those in the lumacaftor–ivacaftor groups (Table S4 in the Supplementary Appendix). Serious adverse events related to abnormal liver function were not observed in the placebo group and were reported for seven patients in the lumacaftor–ivacaftor groups. After discontinuation or interruption of lumacaftor–ivacaftor therapy, liver function in all patients improved substantially, and results of liver-function tests returned to baseline in the case of six patients. Details regarding these events, including concomitant elevations in bilirubin, are provided in the Supplementary Appendix.
DISCUSSION
Significant improvements in the percentage of predicted FEV1 were seen in all four lumacaftor–ivacaftor treatment groups in the TRAFFIC and TRANSPORT studies. In both dose groups in each study, improvements in FEV1 were seen by day 15 and were sustained throughout the 24-week study period.
Lumacaftor–ivacaftor combination therapy resulted in improvements in multiple clinical end points, and the findings were generally consistent across dose groups and studies. Clinically important reductions in the rate of pulmonary exacerbations were also observed in association with lumacaftor–ivacaftor therapy. Through 24 weeks, the lumacaftor–ivacaftor groups had reductions in the rate of pulmonary exacerbations, with decreases in the numbers of events leading to hospitalization or intravenous antibiotic treatment. FEV1 and rates of pulmonary exacerbations are strong predictors of survival and thus remain important for the evaluation of new therapies for cystic fibrosis.25
Significant improvements (i.e., increases) in BMI were observed in the TRANSPORT study and in the pooled analyses but not in the TRAFFIC study. Across both studies, BMI continued to increase during the study period in both lumacaftor–ivacaftor groups. Although the mechanisms for improvement in the nutritional status of patients with cystic fibrosis are not fully defined, the gains are hypothesized to reflect either better caloric absorption, possibly due to normalized intestinal pH,17 or a reduction in energy expenditure resulting from amelioration of lung disease.17,26 Numerical increases in the CFQ-R respiratory domain score favoring active treatment were seen in both dose groups in both studies; however, in the pooled analysis of that score, the treatment difference was significant only in the LUM (600 mg/day)–IVA group and did not meet the requirement for a minimum clinically important difference (4 points).24 It is challenging to interpret these results, given the significant improvements in FEV1. The CFQ-R instrument is valuable for assessing patient-reported outcomes; however, there is precedent for a lack of correlation with FEV1. Studies of tobramycin showed no correlation between changes in CFQ-R and FEV1.24 It is also worth noting that the CFQ-R minimum clinically important difference was established as a within-group change in patients who had markers of advanced disease, which complicates its application to other populations.24
The TRAFFIC and TRANSPORT study cohorts were a population with well-managed cystic fibrosis, as evidenced by the minimal FEV1 deterioration in the placebo group and the high rates of the use of standard cystic fibrosis therapy. The magnitude of the change in FEV1 was significant and was in the range of the magnitudes of change seen in studies of other cystic fibrosis therapeutics.27–31 The changes due to treatment in the percentage of predicted FEV1 were largely consistent across studies, dose groups, and all subgroups analyzed, including subgroups defined according to age, baseline FEV1 (<40 vs. ≥40), and status with respect to Pseudomonas aeruginosa infection. Improvements in FEV1 and BMI and reductions in exacerbations were observed while patients continued to use their prescribed cystic fibrosis therapies; lumacaftor–ivacaftor is therefore expected to provide a clinically meaningful benefit in addition to the standard of care. The determination of the potential for lumacaftor–ivacaftor–mediated CFTR modulation to modify the course of disease will require additional analyses and longer-term data.
Although the improvements in FEV1 associated with lumacaftor–ivacaftor were significant and consistent with in vitro11 and phase 2 sweat chloride and FEV1 results,21 the effect of lumacaftor–ivacaftor on sweat chloride and FEV1 was smaller than that observed in patients with the Gly551Asp mutation who were treated with ivacaftor monotherapy.13,14 Whereas CFTR with the p.Gly551Asp mutation has a gating defect but is found at the cell surface, CFTR with the p.Phe-508del mutation has multiple defects, which makes addressing the underlying cause of disease in patients homozygous for this mutation more complex. The most important of these defects is a substantial reduction in processing and transport to the cell surface, plus a reduced stability and channel gating of the few surface-localized proteins. These multiple defects make restoring p.Phe508del CFTR activity and subsequent observation of a clinical benefit more challenging than addressing the p.Gly551Asp gating defect. The smaller changes in sweat chloride and FEV1 seen in association with lumacaftor–ivacaftor therapy in patients homozygous for Phe508del, as compared with the changes seen in association with ivacaftor monotherapy in patients with Gly551Asp, was predicted in vitro and may be due in part to the fact that lumacaftor only partially rescues the p.Phe508del CFTR processing defect,11 which results in fewer p.Phe508del CFTR channels at the cell surface than are seen with p.Gly551Asp CFTR.
Two in vitro studies have suggested that treatment (for ≤48 hours) with potentiators, including ivacaftor, may reduce the stability and expression of corrected p.Phe508del.32,33 Although it is possible that ivacaftor affects the steady-state levels of corrected p.Phe508del CFTR in vitro, the results of the TRAFFIC and TRANSPORT studies, which included more than 1100 patients, suggest that lumacaftor–ivacaftor provides a clinical benefit that is greater than that previously observed with either agent alone.20,21 Moreover, the clinical benefit was sustained for the entire duration of the studies. Nevertheless, the differences between the results of treatment with lumacaftor–ivacaftor in patients with the Phe508del mutation and treatment with ivacaftor in patients with the Gly551Asp mutation point to the need for continued development of CFTR modulators that will further improve on the meaningful FEV1 benefits observed in the TRAFFIC and TRANSPORT studies.
Lumacaftor–ivacaftor therapy at both dosing regimens generally had an acceptable side-effect profile. The proportion of patients who discontinued the study regimen for reasons related to an adverse event was higher among those who received lumacaftor–ivacaftor than among those who received placebo, and dyspnea and chest tightness were reported more frequently in the active-treatment groups. In a phase 2 study, treatment with lumacaftor monotherapy was associated with an initial increased risk of dyspnea or chest tightness, although these symptoms were uncommon after the addition of ivacaftor to lumacaftor.21 Elevated levels of liver enzymes were observed in a similar number of patients in the active-treatment groups and the placebo group; however, serious adverse events related to elevation of liver enzymes were reported only in the active-treatment group.
The TRAFFIC and TRANSPORT studies included the same two doses of lumacaftor so that we could ascertain whether there was a dose response for the CFTR corrector. Pooled across the two studies, the dose regimens appeared to have similar efficacy and safety profiles, with no clear differentiation except with respect to pulmonary exacerbation–related outcomes, which consistently favored the LUM (400 mg every 12 hr)–IVA group.
In conclusion, in the TRAFFIC and TRANSPORT studies, lumacaftor in combination with ivacaftor improved FEV1 and reduced the rate of pulmonary exacerbations in patients with cystic fibrosis who were homozygous for the Phe508del CFTR mutation. Lumacaftor–ivacaftor therapy generally had an acceptable side-effect profile, with more than 93% of patients completing the assigned therapy regimen. These data show that the combination of a CFTR corrector and potentiator, designed to address the underlying cause of cystic fibrosis by targeting CFTR, can benefit patients who are homozygous for the Phe508del CFTR mutation and represents a treatment milestone for the 45% of patients with cystic fibrosis who are homozygous for this mutation.
Supplementary Material
Acknowledgments
Supported by Vertex Pharmaceuticals; a program grant from the Children’s Hospital Foundation, Brisbane, Queensland, Australia (to Dr. Wainwright); the Northern Ireland Clinical Research Network (Respiratory Health) in Belfast Health and Social Care Trust (to Dr. Elborn); grants from the Institute of Translational Health Sciences, National Institutes of Health (NIH) (UL1TR000423) and the Cystic Fibrosis Translational Research Center, NIH (P30DK089507, both to Dr. Ramsey); the National Institute for Health Research Respiratory Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London (to Dr. Davies); the South Carolina Clinical and Translational Research Institute, Medical University of South Carolina (UL1TR000062 to Dr. Flume); the Clinical and Translational Science Collaborative of Cleveland (UL1TR000439), a grant from the Cystic Fibrosis Core Center (DK027651), and a grant from the Cystic Fibrosis Foundation Therapeutics Development Network to Case Western Reserve University School of Medicine (all to Dr. Konstan); grants from the Northwestern University Clinical and Translational Sciences Institute (UL1RR025741) and the Cystic Fibrosis Foundation Therapeutics Development Network (MCCOLL14YO) (both to Dr. McColley); grants from the UAB Center for Clinical and Translational Science (UL1TR000165), the UAB Cystic Fibrosis Research Center (DK072482), and the Cystic Fibrosis Foundation (all to Dr. Rowe); and the Johns Hopkins Institute for Clinical and Translational Research, which is funded in part by a grant from the NIH (UL1TR001079, to Dr. Boyle).
We thank all the patients, study coordinators, and study investigators; members of the Cystic Fibrosis Foundation, the United States Cystic Fibrosis Foundation Therapeutics Development Network, the European Clinical Trials Network, and the Cystic Fibrosis Foundation Data and Safety Monitoring Board for their support of this trial; Elizabeth Dorn, Ph.D. (Vertex Pharmaceuticals), for providing medical writing, editorial, and coordination support; and Jonathan Kirk (Vertex Pharmaceuticals) for providing graphic design support.
APPENDIX
The authors’ full names and academic degrees are as follows: Claire E. Wainwright, M.B., B.S., M.D., J. Stuart Elborn, M.D., Bonnie W. Ramsey, M.D., Gautham Marigowda, M.D., Xiaohong Huang, Ph.D., Marco Cipolli, M.D., Carla Colombo, M.D., Jane C. Davies, M.D., Kris De Boeck, M.D., Patrick A. Flume, M.D., Michael W. Konstan, M.D., Susanna A. McColley, M.D., Karen McCoy, M.D., Edward F. McKone, M.D., Anne Munck, M.D., Felix Ratjen, M.D., Steven M. Rowe, M.D., M.S.P.H., David Waltz, M.D., and Michael P. Boyle, M.D., for the TRAFFIC and TRANSPORT Study Groups.
The authors’ affiliations are as follows: Queensland Children’s Medical Research Institute, Royal Children’s Hospital, Lady Cilento Children’s Hospital, and University of Queensland School of Medicine, Brisbane, Australia (C.E.W.); Queens University of Belfast, Belfast (J.S.E.), and Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London (J.C.D.) — all in the United Kingdom; Seattle Children’s Hospital and University of Washington School of Medicine, Seattle (B.W.R.); Vertex Pharmaceuticals, Boston (G.M., X.H., D.W.); Cystic Fibrosis Center, Azienda Ospedaliera Universitaria Integrata, Verona (M.C.), and Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, University of Milan, Milan (C.C.) — both in Italy; University Hospital Gasthuisberg, Leuven, Belgium (K.D.B.); Medical University of South Carolina, Charleston (P.A.F.); Case Western Reserve University School of Medicine, Rainbow Babies and Children’s Hospital, Cleveland (M.W.K.), and the Department of Pediatrics, Pulmonary Division, Nationwide Children’s Hospital and Ohio State University, Columbus (K.M.) — both in Ohio; Stanley Manne Children’s Research Institute, Northwestern University Feinberg School of Medicine, Chicago (S.A.M.); St. Vincent’s University Hospital and University College Dublin School of Medicine, Dublin (E.F.M.); Hôpital Robert Debré, Paediatric Gastroenterology and Respiratory Department, CF Center, Assistance Publique–Hôpitaux de Paris, Université Paris 7, Paris (A.M.); Division of Respiratory Medicine, Department of Pediatrics, Physiology, and Experimental Medicine, Hospital for Sick Children, University of Toronto, Toronto (F.R.); University of Alabama at Birmingham, Birmingham (S.M.R.); and Johns Hopkins Medicine, Baltimore (M.P.B.).
Footnotes
Dr. Wainwright reports receiving consulting fees from Medscape and Vertex, lecture fees and travel support from Vertex and Novartis, grant support from Vertex, GlaxoSmithKline, and Novo Nordisk, and fees on a per patient basis as principal investigator of a clinical study from Boehringer Ingelheim. Dr. Ramsey reports receiving grant support from Achaogen, Apartia, Bayer Healthcare, Breathe Easy, Bristol-Myers Squibb, Catabasis, 12th Man Technologies, Caltaxsys, Corbus Pharmaceuticals, Cornerstone Therapeutics, CSL Behring, CURx Pharmaceuticals, Eli Lilly, Flatley Discovery Lab, Genentech, Gilead Sciences, GlycoMimetics, Grifols Therapeutics, INC Research, Insmed, KaloBios, Kamada, Mpex Pharmaceuticals, N30 Pharmaceuticals, Nordmark, Novartis, Parion Sciences, Pharmagenesis (Cornerstone 281), Pharmaxis, ProQR Therapeutics, Pulmatrix, PulmoFlow, Respira Therapeutics, Savara Pharmaceuticals, and Vertex. Dr. Colombo reports receiving fees for serving on advisory boards from Vertex. Dr. Davies reports receiving fees through her institution for serving on advisory boards for Vertex, Proteostasis, Novartis, and Gilead; she has also received fees through her institution from Vertex for participation in educational activities and acting as lead investigator in other trials. Dr. De Boeck reports receiving fees for serving on an advisory board from Pharmaxis and KaloBios, fees for serving on a data monitoring committee from Aptalis, and consulting fees from Ablynx, Galapagos, Gilead, PTC Therapeutics, Celtaxys, and Boehringer Ingelheim; she has also served as principal investigator in studies funded by Gilead, Pharmaxis, and PTC Therapeutics. Dr. Flume reports receiving consulting fees and grant support from Vertex. Dr. Konstan reports receiving fees for serving on advisory boards from Genentech, Gilead Sciences, Insmed, and Savara Pharmaceuticals, consulting fees from Digestive Care, Novartis, PTC Therapeutics, Chiesi, KaloBios, and Celtaxsys, lecture fees from Novartis, travel support from Genentech, Gilead Sciences, Insmed, Novartis, PTC Therapeutics, and Celtaxsys, and grant support through his institution from Genentech, Insmed, Novartis, PTC Therapeutics, Savara Pharmaceuticals, and KaloBios. Dr. McCoy reports receiving travel support from Novartis and Pharmaxis, and grant support through her institution from Aptalis, KaloBios, Novartis, Gilead Sciences, Pharmaxis, Savara Pharmaceuticals, Genentech, AbbVie, Janssen, and N30 Pharmceuticals. Dr. McKone reports receiving fees for serving on advisory boards from Novartis and Vertex, consulting fees from Vertex, lecture fees from Gilead Sciences, travel support from Gilead Sciences and Novartis, and grant support from Vertex. Dr. Munck reports receiving fees for serving on advisory boards from Novartis. Dr. Ratjen reports receiving consulting fees from Bayer, Talecris, CSL Behring, Roche, Gilead Sciences, Genentech, and KaloBios, travel support from PARI Pharma, and grant support from Novartis. Dr. Rowe reports receiving grant support from Vertex, PTC Therapeutics, Novartis, and the Forest Research Institute. Dr. Boyle reports receiving fees for serving on advisory boards for Savara Pharmaceuticals, Vertex, Genentech, and Novartis. Dr. Marigowda, Dr. Huang, and Dr. Waltz are employees of and hold stock or stock options in Vertex. No other potential conflict of interest relevant to this article was reported.
The authors’ full names, academic degrees, and affiliations are listed in the Appendix
Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.
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