Original Article

Elexacaftor–Tezacaftor–Ivacaftor for Cystic Fibrosis with a Single Phe508del Allele

List of authors.
  • Peter G. Middleton, M.D.,
  • Marcus A. Mall, M.D.,
  • Pavel Dřevínek, M.D.,
  • Larry C. Lands, M.D.,
  • Edward F. McKone, M.D.,
  • Deepika Polineni, M.D.,
  • Bonnie W. Ramsey, M.D.,
  • Jennifer L. Taylor-Cousar, M.D.,
  • Elizabeth Tullis, M.D.,
  • François Vermeulen, M.D.,
  • Gautham Marigowda, M.D.,
  • Charlotte M. McKee, M.D.,
  • Samuel M. Moskowitz, M.D.,
  • Nitin Nair, Ph.D.,
  • Jessica Savage, M.D.,
  • Christopher Simard, M.D.,
  • Simon Tian, M.D.,
  • David Waltz, M.D.,
  • Fengjuan Xuan, Ph.D.,
  • Steven M. Rowe, M.D.,
  • and Raksha Jain, M.D.
  • for the VX17-445-102 Study Group*

Abstract

Background

Cystic fibrosis is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, and nearly 90% of patients have at least one copy of the Phe508del CFTR mutation. In a phase 2 trial involving patients who were heterozygous for the Phe508del CFTR mutation and a minimal-function mutation (Phe508del–minimal function genotype), the next-generation CFTR corrector elexacaftor, in combination with tezacaftor and ivacaftor, improved Phe508del CFTR function and clinical outcomes.

Methods

We conducted a phase 3, randomized, double-blind, placebo-controlled trial to confirm the efficacy and safety of elexacaftor–tezacaftor–ivacaftor in patients 12 years of age or older with cystic fibrosis with Phe508del–minimal function genotypes. Patients were randomly assigned to receive elexacaftor–tezacaftor–ivacaftor or placebo for 24 weeks. The primary end point was absolute change from baseline in percentage of predicted forced expiratory volume in 1 second (FEV1) at week 4.

Results

A total of 403 patients underwent randomization and received at least one dose of active treatment or placebo. Elexacaftor–tezacaftor–ivacaftor, relative to placebo, resulted in a percentage of predicted FEV1 that was 13.8 points higher at 4 weeks and 14.3 points higher through 24 weeks, a rate of pulmonary exacerbations that was 63% lower, a respiratory domain score on the Cystic Fibrosis Questionnaire–Revised (range, 0 to 100, with higher scores indicating a higher patient-reported quality of life with regard to respiratory symptoms; minimum clinically important difference, 4 points) that was 20.2 points higher, and a sweat chloride concentration that was 41.8 mmol per liter lower (P<0.001 for all comparisons). Elexacaftor–tezacaftor–ivacaftor was generally safe and had an acceptable side-effect profile. Most patients had adverse events that were mild or moderate. Adverse events leading to discontinuation of the trial regimen occurred in 1% of the patients in the elexacaftor–tezacaftor–ivacaftor group.

Conclusions

Elexacaftor–tezacaftor–ivacaftor was efficacious in patients with cystic fibrosis with Phe508del–minimal function genotypes, in whom previous CFTR modulator regimens were ineffective. (Funded by Vertex Pharmaceuticals; VX17-445-102 ClinicalTrials.gov number, NCT03525444.)

Introduction

Visual Abstract for 'Elexacaftor&#x2013;Tezacaftor&#x2013;Ivacaftor for Cystic Fibrosis with a Single Phe508del Allele,' P.G. Middleton and Others (10.1056/NEJMoa1908639)VISUAL ABSTRACT
Elexacaftor–Tezacaftor–Ivacaftor for Cystic Fibrosis

Cystic fibrosis is a lethal, inherited, autosomal recessive disorder that affects approximately 80,000 people worldwide and is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein that lead to reduced CFTR function.1-3 CFTR codes for an epithelial anion channel that transports both Cl and HCO3 across epithelial surfaces in the respiratory tract, pancreas, gastrointestinal system, and sweat glands, among other organs.1,2,4,5 Although there are hundreds of different disease-causing mutations, nearly 90% of persons with cystic fibrosis have at least one copy of the most common mutation, the Phe508del CFTR mutation.6

The Phe508del CFTR mutation causes defective intracellular processing and trafficking and decreased stability, which drastically reduces the quantity of CFTR protein at the apical surface of epithelial cells.4,7,8 Phe508del CFTR protein also exhibits defective channel gating, which further limits anion transport.7 To restore Phe508del CFTR function, these molecular defects need to be addressed.

CFTR modulators treat the underlying cause of disease and have improved clinical outcomes in persons with specific CFTR mutations.9-12 These medications include small-molecule correctors that increase cell-surface expression by improving the processing and trafficking of CFTR, as well as small-molecule potentiators that augment channel gating.13 For persons with cystic fibrosis who are homozygous for the Phe508del CFTR mutation, the combination of a single corrector, either lumacaftor or tezacaftor, with the potentiator ivacaftor improves clinical outcomes, including lung function and the rate of pulmonary exacerbations.9,11 However, neither of these dual combinations is sufficiently effective in persons with cystic fibrosis who have a single Phe508del allele and a second CFTR mutation that does not respond to current CFTR modulator therapy.14,15 Such mutations are termed “minimal function” because of the complete absence of protein production or lack of in vitro responsiveness to ivacaftor and tezacaftor–ivacaftor.16,17 For these patients, no treatment is available to treat the underlying cause of disease.

We studied the effect of a triple-combination CFTR modulator regimen in patients with cystic fibrosis who have a single Phe508del allele. The combination includes the next-generation corrector elexacaftor plus the corrector tezacaftor and the potentiator ivacaftor to more fully restore the function of Phe508del CFTR.18 In proof-of-concept trials that evaluated this therapeutic approach,16,18 elexacaftor–tezacaftor–ivacaftor led to improvements in spirometry, patient-reported respiratory symptoms, and sweat chloride concentration, a marker of CFTR activity, in patients with cystic fibrosis with a single Phe508del allele.18 To confirm efficacy and safety in this population, we conducted a randomized, placebo-controlled, phase 3 trial (VX17-445-102) of elexacaftor–tezacaftor–ivacaftor in patients who were heterozygous for the Phe508del CFTR mutation and a minimal-function mutation (Phe508del–minimal function genotypes).

Methods

Participants, Trial Design, and Oversight

This phase 3, multicenter, randomized, double-blind, placebo-controlled trial of elexacaftor–tezacaftor–ivacaftor involved patients 12 years of age or older with cystic fibrosis and Phe508del–minimal function genotypes. Patients were eligible for inclusion if they had a percentage of predicted forced expiratory volume in 1 second (FEV1) of 40 to 90% at screening and had stable disease during the 28-day screening period before the first dose of active treatment or placebo. Details of the protocol have been described previously,17 and the protocol and statistical analysis plan are provided with the full text of this article at NEJM.org. (For complete inclusion and exclusion criteria and details on end points and the statistical analysis, see the Supplementary Appendix, available at NEJM.org; qualifying minimal-function mutations are listed in Table S1 in the Supplementary Appendix.)

The trial had a 4-week screening period and 24-week intervention period (Fig. S1). Patients were randomly assigned in a 1:1 ratio to receive elexacaftor (200 mg once daily) in triple combination with tezacaftor (100 mg once daily) and ivacaftor (150 mg every 12 hours) or matched placebos. Randomization was performed in permuted blocks, with stratification according to percentage of predicted FEV1 at screening (<70% vs. ≥70%), age at screening (<18 years vs. ≥18 years), and sex. Patients who completed the intervention period could enroll in an ongoing 96-week open-label extension study in which all patients receive active treatment (VX17-445-105; ClinicalTrials.gov number, NCT03525574).

The trial was designed by Vertex Pharmaceuticals in collaboration with the authors. Data gathering and analysis were performed by Vertex Pharmaceuticals in collaboration with the authors and the VX17-445-102 Study Group. The clinical trial protocol and informed-consent forms were approved by an independent ethics committee at each site. Each enrolled patient, or the patient’s legal guardian, provided written informed consent (and assent, when appropriate). Safety was monitored by an independent data monitoring committee. All authors had full access to the trial data after final database lock and critically reviewed the manuscript. The first two authors and last two authors wrote the first draft of the manuscript and made final decisions regarding the content of the submitted manuscript. All authors approved the manuscript for submission. The investigators vouch for the accuracy and completeness of the data generated at their respective sites, and the investigators and Vertex Pharmaceuticals vouch for the fidelity of the trial to the protocol. Confidentiality agreements were in place between the sponsor and each investigative site during the trial.

End Points

The primary end point was absolute change from baseline in percentage of predicted FEV1 at week 4. Key secondary end points were absolute change from baseline in percentage of predicted FEV1 through week 24, number of pulmonary exacerbations through week 24, absolute change from baseline in sweat chloride concentration through week 24, absolute change from baseline in the Cystic Fibrosis Questionnaire–Revised (CFQ-R) respiratory domain score (range, 0 to 100, with higher scores indicating a higher patient-reported quality of life with regard to respiratory symptoms; minimum clinically important difference, 4 points) through week 24, absolute change from baseline in body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) at week 24, absolute change from baseline in sweat chloride concentration at week 4, and absolute change from baseline in the CFQ-R respiratory domain score at week 4. Other secondary end points included time to first pulmonary exacerbation through week 24, absolute change from baseline in BMI-for-age z score at week 24, absolute change from baseline in body weight at week 24, and safety and side-effect profile.

Statistical Analysis

Efficacy analyses included all patients who underwent randomization and received at least one dose of elexacaftor–tezacaftor–ivacaftor or placebo. The absolute change from baseline in percentage of predicted FEV1 at week 4 was analyzed with the use of a mixed-effects model for repeated measures, with change from baseline in percentage of predicted FEV1 as the dependent variable. The model included trial group, visit, and trial-group–by–visit interaction as fixed effects, with continuous baseline percentage of predicted FEV1, age at screening (<18 years vs. ≥18 years), and sex as covariates; the model used an unstructured covariance for the within-patient errors. A similar mixed-effects model for repeated measures was applied to analyses of the key secondary end points of percentage of predicted FEV1 through week 24, sweat chloride concentration, CFQ-R respiratory domain score, and BMI. The number of pulmonary exacerbations was analyzed with the use of a negative binomial-regression model.

A prespecified interim analysis was conducted for the primary end point when at least 140 patients had completed the week 4 visit and at least 100 patients had completed the week 12 visit. A Lan–DeMets alpha-spending function was applied to control the overall type I error rate of 0.05 for the primary end point. Assuming a 5% dropout rate at week 4 and a within-group standard deviation of 7 percentage points, we estimated that an interim-analysis sample size of 70 patients per trial group would provide approximately 98% power to detect a between-group difference of 5.0 points for the mean absolute change from baseline in percentage of predicted FEV1 at week 4, using a two-sided, two-sample t-test at a significance level of 0.044 based on the alpha-spending function. Safety analyses were descriptive and included all patients who received at least one dose of elexacaftor–tezacaftor–ivacaftor or placebo.

Results

Population

Demographic and Clinical Characteristics of the Patients at Baseline.

The trial was conducted at 115 sites in 13 countries from June 2018 to April 2019. Overall, 405 patients underwent randomization, and 403 received at least one dose of the trial regimen (200 in the elexacaftor–tezacaftor–ivacaftor group and 203 in the placebo group) (Fig. S2). At baseline, the trial groups were well matched (Table 1 and Table S2). The mean adherence to the trial regimen was more than 98% in both trial groups. All 400 patients who completed the intervention period were enrolled in the open-label extension study.

Efficacy

Primary and Key Secondary Efficacy End Points. Absolute Change from Baseline in Percentage of Predicted FEV1, and Rate of Pulmonary Exacerbations.

Panel A shows the absolute change from baseline in percentage of predicted forced expiratory volume in 1 second (FEV1), based on a mixed-effects model for repeated measures. Data are least-squares means, and 𝙸 bars indicate standard error of the mean; the dashed line indicates no change from baseline. Panel B shows a histogram of absolute change from baseline in percentage of predicted FEV1 through week 24, according to trial group. Panel C shows the overall estimated annualized rate of pulmonary exacerbations, the estimated annualized rate of pulmonary exacerbations leading to hospitalization, and the estimated annualized rate of pulmonary exacerbations treated with intravenous antibiotics. CI denotes confidence interval.

Treatment with elexacaftor–tezacaftor–ivacaftor resulted in significant improvement in the primary end point of absolute change in percentage of predicted FEV1 at week 4, assessed at the interim analysis, with a mean treatment difference of 13.8 points relative to placebo (P<0.001) (Table 2 and Figure 1A). Sustained improvement in percentage of predicted FEV1 was seen through week 24 (final analysis), with a mean treatment difference of 14.3 points relative to placebo (P<0.001) (Table 2 and Figure 1A). The histogram of absolute change in percentage of predicted FEV1 through week 24 showed marked separation of the two trial groups (Figure 1B).

Subgroup analysis for absolute change in percentage of predicted FEV1 at week 4 showed that the mean treatment difference was consistent across all prespecified subgroups (Fig. S3). This difference was also consistent in the subgroup of patients in whom the minimal-function mutation caused an absence of CFTR protein production (78.0% of the trial population) and those with missense or in-frame deletion mutations (Table S3). Patients with a percentage of predicted FEV1 of less than 40% at baseline (8.4% of the trial population) had a similar magnitude change in percentage of predicted FEV1 at week 4 as the overall population (Table S4).

Treatment with elexacaftor–tezacaftor–ivacaftor resulted in a 63% lower annualized rate of pulmonary exacerbations than placebo (rate ratio, 0.37; 95% confidence interval, 0.25 to 0.55; P<0.001) (Table 2). A similar benefit was seen with respect to the rate of exacerbations that led to hospitalization or that were treated with intravenous antibiotics (Figure 1C). A higher percentage of patients in the elexacaftor–tezacaftor–ivacaftor group than in the placebo group remained free of pulmonary exacerbations (Fig. S4).

Absolute Change from Baseline in Sweat Chloride Concentration and CFQ-R Respiratory Domain Score.

Panel A shows the absolute change from baseline in sweat chloride concentration, based on a mixed-effects model for repeated measures; a reduction over time indicates improvement in CFTR function. Panel B shows a histogram of absolute change from baseline in sweat chloride concentration through week 24, according to trial group. Panel C shows the absolute change from baseline in the respiratory domain score on the Cystic Fibrosis Questionnaire–Revised (CFQ-R), based on a mixed-effects model for repeated measures. Scores are normalized to range from 0 to 100 points, with higher scores indicating a higher patient-reported quality of life with regard to respiratory symptoms; the minimum clinically important difference is 4 points. In Panels A and C, least-squares means at each visit are shown, and the 𝙸 bars indicate the corresponding standard error; the dashed line indicates no change from baseline.

Sweat chloride concentrations improved significantly through week 24, with a mean treatment difference of −41.8 mmol per liter relative to placebo (P<0.001) (Table 2 and Figure 2A). The histogram of absolute change in sweat chloride concentration through week 24 showed separation of the two groups (Figure 2B). The mean sweat chloride concentration in the elexacaftor–tezacaftor–ivacaftor group at week 24 was 57.9 mmol per liter, as compared with 102.4 mmol per liter in the placebo group (Fig. S5).

The CFQ-R respiratory domain score improved significantly through week 24 in the elexacaftor–tezacaftor–ivacaftor group, with a mean treatment difference of 20.2 points relative to placebo (P<0.001) (Table 2 and Figure 2C). BMI also improved significantly at week 24, with a mean treatment difference of 1.04 relative to placebo (P<0.001) (Table 2 and Fig. S6). All additional secondary efficacy end points showed improvement (Table 2 and Table S5).

Safety

Adverse Events.

Table 3 provides an overview of adverse events. The percentage of patients with at least one adverse event was 93.1% in the elexacaftor–tezacaftor–ivacaftor group and 96.0% in the placebo group; excluding adverse events of pulmonary exacerbation, the percentage was 92.6% in the elexacaftor–tezacaftor–ivacaftor group and 93.0% in the placebo group. Adverse events occurring in at least 10% of patients in either trial group were consistent with common manifestations and complications of cystic fibrosis. The majority of patients in the elexacaftor–tezacaftor–ivacaftor group had adverse events that were mild (33.2%) or moderate (50.5%) in severity. The large majority of adverse events resolved during the trial.

Serious adverse events occurred in 28 patients (13.9%) in the elexacaftor–tezacaftor–ivacaftor group and 42 patients (20.9%) in the placebo group (Table 3 and Table S6); excluding serious adverse events of pulmonary exacerbation, serious adverse events occurred in 20 patients (9.9%) in the elexacaftor–tezacaftor–ivacaftor group and 16 patients (8.0%) in the placebo group. There were no deaths in either trial group. Two patients (1.0%) in the elexacaftor–tezacaftor–ivacaftor group discontinued the trial regimen because of adverse events: rash in 1 patient and portal hypertension in a patient with preexisting cirrhosis. No patients in the placebo group discontinued the trial regimen because of an adverse event.

On the basis of previous experience with CFTR modulator therapy,9-12 including the phase 2 trial of elexacaftor–tezacaftor–ivacaftor,18 data related to aminotransferase levels and rash were reviewed. Adverse events of elevated aminotransferase levels occurred in 22 patients (10.9%) in the elexacaftor–tezacaftor–ivacaftor group and 8 patients (4.0%) in the placebo group. In the elexacaftor–tezacaftor–ivacaftor group, elevated levels of alanine aminotransferase or aspartate aminotransferase that were greater than three times, greater than five times, and greater than eight times the upper limit of the normal range occurred in 16 patients (7.9%), 5 patients (2.5%), and 3 patients (1.5%), respectively, as compared with 11 patients (5.5%), 3 patients (1.5%), and 2 patients (1.0%) in the placebo group. No patient had an elevated aminotransferase level greater than three times the upper limit of the normal range concurrent with an elevated bilirubin level greater than two times the upper limit of the normal range that emerged during the intervention period. Rash occurred in 22 patients (10.9%) in the elexacaftor–tezacaftor–ivacaftor group and 13 patients (6.5%) in the placebo group. In both trial groups, rash was more common in female patients than in male patients and more common in female patients who used hormonal contraceptives than in those who did not (Table S7).

Additional observations included elevated levels of creatine kinase and blood-pressure changes in the elexacaftor–tezacaftor–ivacaftor group. Elevated levels of creatine kinase were often associated with exercise, and no elevations of creatine kinase led to discontinuation of the trial regimen (Table S8). The baseline mean systolic and diastolic blood pressures in the elexacaftor–tezacaftor–ivacaftor group were 113.4 mm Hg and 69.4 mm Hg, and they increased by 3.1 mm Hg and 1.9 mm Hg, respectively, at week 24 (Table S9). There were no relevant safety findings in other clinical or laboratory assessments.

Discussion

In this 24-week trial of triple-combination CFTR modulator therapy in patients with cystic fibrosis who have a single Phe508del allele, elexacaftor–tezacaftor–ivacaftor treatment resulted in improvements in lung function, the rate of pulmonary exacerbations, sweat chloride concentration, CFQ-R respiratory domain scores, and BMI and was generally safe with an acceptable side-effect profile, findings that are consistent with those of the phase 2 trial of elexacaftor–tezacaftor–ivacaftor.18 The efficacy outcomes confirm the hypothesis that elexacaftor–tezacaftor–ivacaftor effectively modulates the function of Phe508del CFTR from a single allele, providing pronounced benefits in a population of patients in whom previous CFTR modulator therapies were not effective.15,19

Elexacaftor–tezacaftor–ivacaftor therapy improved multiple outcome measures. FEV1 is a strong predictor of clinical status in cystic fibrosis,20 and elexacaftor–tezacaftor–ivacaftor resulted in sustained improvements in this end point. Pulmonary exacerbations are important clinical events associated with disease progression21-24; elexacaftor–tezacaftor–ivacaftor resulted in a lower rate of pulmonary exacerbations, including severe events leading to hospitalization or treatment with intravenous antibiotics, than placebo. Improvements in respiratory symptoms and in systemic indicators of clinical benefit, including nutritional outcomes, were also noted.

The current benchmark for highly effective CFTR modulator therapy is ivacaftor for patients with the Gly551Asp CFTR mutation,10 in whom disease modification has been shown with long-term use, including decreased lung-function decline and decreased mortality.25-28 The improvement in the primary end point of absolute change in percentage of predicted FEV1 was 10.6 points in patients with the Gly551Asp allele.10 In the present trial of elexacaftor–tezacaftor–ivacaftor in patients with a single Phe508del allele, the improvement in percentage of predicted FEV1 was 13.8 points, relative to placebo. Furthermore, the mean sweat chloride concentration in patients with a single Phe508del allele who received elexacaftor–tezacaftor–ivacaftor for 24 weeks decreased from 102 mmol per liter to 58 mmol per liter, just below the generally accepted diagnostic threshold for cystic fibrosis (≥60 mmol per liter)29; this finding reflects improved CFTR function.

Ivacaftor and tezacaftor–ivacaftor, two components of this triple combination, are approved therapies, with well-characterized safety profiles.10-12,30 Similar to these agents, elexacaftor–tezacaftor–ivacaftor therapy was associated with adverse events that were mostly mild to moderate, that generally represented common manifestations of cystic fibrosis, and that led to few treatment discontinuations. An increase in the incidence of elevated aminotransferase levels, which occur sporadically in many persons with cystic fibrosis, was observed with elexacaftor–tezacaftor–ivacaftor treatment; these adverse events were low grade (i.e., mild or moderate) in 20 of 22 patients (91%) and were not treatment-limiting. In general, cases of rash were mild to moderate and did not lead to alteration of treatment administration. The elevated serum levels of creatine kinase that were observed were generally asymptomatic and often associated with exercise. The modest increase in mean blood pressure that was observed with elexacaftor–tezacaftor–ivacaftor may be related to salt preservation,31 improved nutritional status, or other effects of CFTR modulation; evaluation of blood pressure in patients who begin to receive treatment may help to clarify the clinical relevance of this observation.

Unlike previous CFTR modulators, triple-combination therapy with elexacaftor–tezacaftor–ivacaftor strongly modulates CFTR in persons with Phe508del–minimal function genotypes. The effect on Phe508del CFTR was evident in the 78% of patients with minimal-function mutations that are associated with an absence of CFTR protein production, who had a response to elexacaftor–tezacaftor–ivacaftor that could occur only through modulation of Phe508del CFTR. These data support the hypothesis that the presence of a single Phe508del allele is sufficient to impart the benefit of triple-combination therapy independent of the minimal-function mutation. The restoration of Phe508del CFTR by elexacaftor–tezacaftor–ivacaftor was further confirmed by a concurrent phase 3 trial involving patients with two Phe508del alleles, which showed substantially improved outcomes, including increased lung function and decreased patient-reported respiratory symptoms, as compared with the dual combination of tezacaftor–ivacaftor.32 Further research to extend the benefit of CFTR modulation to patients with responsive mutations other than the Phe508del CFTR mutation is imperative.

In conclusion, this 24-week, phase 3 trial involving 403 patients with cystic fibrosis confirmed the efficacy of triple-combination CFTR modulator therapy in patients 12 years of age or older who were heterozygous for the Phe508del CFTR mutation and a minimal-function mutation. No worrisome safety signals were noted. These results provide evidence that elexacaftor–tezacaftor–ivacaftor can modulate a single Phe508del allele in people with cystic fibrosis, thus addressing the underlying cause of disease in the large majority of patients.

Funding and Disclosures

Supported by Vertex Pharmaceuticals. The National Institutes of Health provided grant support to the University of Alabama at Birmingham (P30DK072482, R35HL135816, and U54TR001368) and Seattle Children’s Hospital (P30-DK-089507, 5UL1 TR 0002319, and 1U01TR 002487).

Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.

Dr. Middleton reports receiving advisory board fees, research funding, and clinical-trial support, paid to his institution, from Vertex Pharmaceuticals and clinical-trial support from Proteostasis Therapeutics and Galapagos; Dr. Mall, receiving consulting fees, lecture fees, and travel support from Bayer, advisory board fees, consulting fees, lecture fees, and travel support from Boehringer Ingelheim, advisory board fees, consulting fees, and travel support from Polyphor, advisory board fees and consulting fees from Arrowhead Pharmaceuticals, ProQR Therapeutics, Spyryx Biosciences, Santhera Pharmaceuticals, and Enterprise Therapeutics, grant support, advisory board fees, lecture fees, and travel support from Vertex Pharmaceuticals, consulting fees from Galapagos and Sterna Biologicals, and lecture fees from Celtaxys; Dr. Dřevínek, receiving fees for serving on a clinical trial and consulting fees from Vertex Pharmaceuticals, fees for serving on a clinical trial from Galapagos, Flatley Discovery Lab, and Corbus Pharmaceuticals, and consulting fees from Proteostasis Therapeutics, Actelion Pharmaceuticals, and Chiesi; Dr. Lands, receiving advisory board fees from Proteostasis Therapeutics, serving as chief medical advisor and co-principal investigator of a trial for Laurent Pharmaceuticals, advisory board fees and fees for preparation of educational material from Vertex Pharmaceuticals, and holding patents #60/750,004, #12/097,229, and #14/172,954 on a method for correcting a lipid imbalance in a subject; Dr. McKone, receiving advisory board fees from Proteostasis Therapeutics, grant support from Gilead Sciences, travel support from Novartis, and grant support, advisory board fees, and lecture fees from Vertex Pharmaceuticals; Dr. Polineni, receiving grant support, advisory board fees, and travel support from Vertex Pharmaceuticals and grant support from Proteostasis Therapeutics, Parion Sciences, and Laurent Pharmaceuticals; Dr. Taylor-Cousar, receiving advisory board fees and lecture fees from Gilead Sciences, grant support, paid to her institution, consulting fees, and lecture fees from Proteostasis Therapeutics and Celtaxys, advisory board fees from Protalix Biotherapeutics, consulting fees from Santhera Pharmaceuticals, and grant support, paid to her institution, consulting fees, advisory board fees, and lecture fees from Vertex Pharmaceuticals; Dr. Tullis, receiving grant support, consulting fees, and travel support from Proteostasis Therapeutics, grant support from AbbVie, and grant support, honoraria, consulting fees, and travel support from Vertex Pharmaceuticals; Drs. Marigowda and McKee, being employed by and owning stock in Vertex Pharmaceuticals; Dr. Moskowitz, being employed by and holding stock options in Vertex Pharmaceuticals and holding pending patent PCT/US2018/042486 on methods of treatment for cystic fibrosis and pending patent PCT/US2019/016537 on pharmaceutical compositions for treating cystic fibrosis; Drs. Nair, Savage, Simard, and Tian, being employed by and owning stock in Vertex Pharmaceuticals; Dr. Waltz, being employed by and holding stock options in Vertex Pharmaceuticals and holding pending patent PCT/US2018/042486 on methods of treatment for cystic fibrosis and pending patent PCT/US2019/016537 on pharmaceutical compositions for treating cystic fibrosis; Dr. Xuan, being employed by and holding stock options from Vertex Pharmaceuticals; Dr. Rowe, receiving grant support from Forest Research Institute, AstraZeneca, N30 Pharmaceuticals/Nivalis Therapeutics, Galapagos/AbbVie, Proteostasis Therapeutics, Eloxx Pharmaceuticals, and PTC Therapetics, grant support and consulting fees from Celtaxsys, Bayer, Synspira Therapeutics/Synedgen, and Novartis, grant support, consulting fees, advisory board fees, and in-kind support from Vertex Pharmaceuticals, and consulting fees from Renovion; and Dr. Jain, receiving fees for serving on a speakers bureau from Gilead Sciences, grant support from Sound Pharmaceuticals, Corbus Pharmaceuticals, and Boehringer Ingelheim, and grant support and consulting fees from Vertex Pharmaceuticals. No other potential conflict of interest relevant to this article was reported.

Drs. Middleton and Mall and Drs. Rowe and Jain contributed equally to this article.

This article was published on October 31, 2019, at NEJM.org.

A data sharing statement provided by the authors is available with the full text of this article at NEJM.org.

We thank the patients and their families for participating in this trial and the trial investigators and coordinators for their contributions to the trial; Sarah Garber, Pharm.D., former employee of Vertex Pharmaceuticals, and Swati Thorat, Ph.D., employee of Vertex Pharmaceuticals, who may own stock or stock options in the company, for providing editorial coordination and support; and Karen Kaluza Smith, Ph.D., C.M.P.P., of ArticulateScience for providing editorial assistance under the guidance of the authors and with support from Vertex Pharmaceuticals.

Author Affiliations

From the Department of Respiratory and Sleep Medicine, Westmead Hospital and CF Research Group, Ludwig Engel Centre for Respiratory Research, Westmead Institute for Medical Research, University of Sydney, Westmead, NSW, Australia (P.G.M.); the Department of Pediatric Pulmonology, Immunology, and Intensive Care Medicine, Charité–Universitätsmedizin Berlin, the Berlin Institute of Health, and the German Center for Lung Research, Berlin (M.A.M.); the Department of Medical Microbiology, Department of Pediatrics, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic (P.D.); the Pediatric Respiratory Medicine and Pediatric Cystic Fibrosis Clinic, McGill University Health Centre, Montreal (L.C.L.); St. Vincent’s University Hospital and University College Dublin School of Medicine, Dublin (E.F.M.); the Department of Internal Medicine, University of Kansas Medical Center, Kansas City (D.P.); the Department of Pediatrics, University of Washington School of Medicine, and Seattle Children’s Research Institute, Seattle (B.W.R.); the Departments of Medicine and Pediatrics, National Jewish Health, Denver (J.L.T.-C.); the Division of Respirology, St. Michael’s Hospital, University of Toronto, Toronto (E.T.); the Cystic Fibrosis Reference Center, Department of Pediatrics, Catholic University of Leuven, Leuven, Belgium (F.V.); Vertex Pharmaceuticals, Boston (G.M., C.M.M., S.M.M., N.N., J.S., C.S., S.T., D.W., F.X.); the Departments of Medicine, Pediatrics, and Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham (S.M.R.); and the Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas (R.J.).

Address reprint requests to Dr. Jain at the Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-8558, or at .

The members of the VX17-445-102 Study Group are listed in the Supplementary Appendix, available at NEJM.org.

Supplementary Material

References (32)

  1. 1. O’Sullivan BP, Freedman SD. Cystic fibrosis. Lancet 2009;373:1891-1904.

  2. 2. Elborn JS. Cystic fibrosis. Lancet 2016;388:2519-2531.

  3. 3. Sanders DB, Fink AK. Background and epidemiology. Pediatr Clin North Am 2016;63:567-584.

  4. 4. Rowe SM, Miller S, Sorscher EJ. Cystic fibrosis. N Engl J Med 2005;352:1992-2001.

  5. 5. Quinton PM. Cystic fibrosis: impaired bicarbonate secretion and mucoviscidosis. Lancet 2008;372:415-417.

  6. 6. Marshall B, Faro A, Fink AK, et al. Cystic fibrosis patient registry: 2017 annual data report. Bethesda, MD: Cystic Fibrosis Foundation, 2018.

  7. 7. Dalemans W, Barbry P, Champigny G, et al. Altered chloride ion channel kinetics associated with the delta F508 cystic fibrosis mutation. Nature 1991;354:526-528.

  8. 8. Lukacs GL, Chang XB, Bear C, et al. The delta F508 mutation decreases the stability of cystic fibrosis transmembrane conductance regulator in the plasma membrane: determination of functional half-lives on transfected cells. J Biol Chem 1993;268:21592-21598.

  9. 9. Wainwright CE, Elborn JS, Ramsey BW, et al. Lumacaftor–ivacaftor in patients with cystic fibrosis homozygous for Phe508del CFTR. N Engl J Med 2015;373:220-231.

  10. 10. Ramsey BW, Davies J, McElvaney NG, et al. A CFTR potentiator in patients with cystic fibrosis and the G551D mutation. N Engl J Med 2011;365:1663-1672.

  11. 11. Taylor-Cousar JL, Munck A, McKone EF, et al. Tezacaftor–ivacaftor in patients with cystic fibrosis homozygous for Phe508del. N Engl J Med 2017;377:2013-2023.

  12. 12. Rowe SM, Daines C, Ringshausen FC, et al. Tezacaftor–ivacaftor in residual-function heterozygotes with cystic fibrosis. N Engl J Med 2017;377:2024-2035.

  13. 13. Boyle MP, De Boeck K. A new era in the treatment of cystic fibrosis: correction of the underlying CFTR defect. Lancet Respir Med 2013;1:158-163.

  14. 14. A study to evaluate the efficacy and safety of VX-661 in combination with ivacaftor in subjects aged 12 years and older with cystic fibrosis, heterozygous for the F508del-CFTR mutation: study results. Bethesda, MD: National Institutes of Health, ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/results/NCT02516410).

  15. 15. Rowe SM, McColley SA, Rietschel E, et al. Lumacaftor/ivacaftor treatment of patients with cystic fibrosis heterozygous for F508del-CFTR. Ann Am Thorac Soc 2017;14:213-219.

  16. 16. Davies JC, Moskowitz SM, Brown C, et al. VX-659–tezacaftor–ivacaftor in patients with cystic fibrosis and one or two Phe508del alleles. N Engl J Med 2018;379:1599-1611.

  17. 17. Taylor-Cousar JL, Mall MA, Ramsey BW, et al. Clinical development of triple-combination CFTR modulators for cystic fibrosis patients with one or two F508del alleles. ERJ Open Res 2019;5(2):00082-2019-00082-2019.

  18. 18. Keating D, Marigowda G, Burr L, et al. VX-445–tezacaftor–ivacaftor in patients with cystic fibrosis and one or two Phe508del alleles. N Engl J Med 2018;379:1612-1620.

  19. 19. Clancy JP. Rapid therapeutic advances in CFTR modulator science. Pediatr Pulmonol 2018;53:Suppl 3:S4-S11.

  20. 20. Kerem E, Reisman J, Corey M, Canny GJ, Levison H. Prediction of mortality in patients with cystic fibrosis. N Engl J Med 1992;326:1187-1191.

  21. 21. Amadori A, Antonelli A, Balteri I, Schreiber A, Bugiani M, De Rose V. Recurrent exacerbations affect FEV(1) decline in adult patients with cystic fibrosis. Respir Med 2009;103:407-413.

  22. 22. De Boer K, Vandemheen KL, Tullis E, et al. Exacerbation frequency and clinical outcomes in adult patients with cystic fibrosis. Thorax 2011;66:680-685.

  23. 23. Konstan MW, Wagener JS, Vandevanter DR, et al. Risk factors for rate of decline in FEV1 in adults with cystic fibrosis. J Cyst Fibros 2012;11:405-411.

  24. 24. Sanders DB, Zhao Q, Li Z, Farrell PM. Poor recovery from cystic fibrosis pulmonary exacerbations is associated with poor long-term outcomes. Pediatr Pulmonol 2017;52:1268-1275.

  25. 25. Sawicki GS, McKone EF, Pasta DJ, et al. Sustained benefit from ivacaftor demonstrated by combining clinical trial and cystic fibrosis patient registry data. Am J Respir Crit Care Med 2015;192:836-842.

  26. 26. Volkova N, Moy K, Evans J, et al. Disease progression in patients with cystic fibrosis treated with ivacaftor: data from national US and UK registries. J Cyst Fibros 2019 June 10 (Epub ahead of print).

  27. 27. Rowe SM, Heltshe SL, Gonska T, et al. Clinical mechanism of the cystic fibrosis transmembrane conductance regulator potentiator ivacaftor in G551D-mediated cystic fibrosis. Am J Respir Crit Care Med 2014;190:175-184.

  28. 28. Bessonova L, Volkova N, Higgins M, et al. Data from the US and UK cystic fibrosis registries support disease modification by CFTR modulation with ivacaftor. Thorax 2018;73:731-740.

  29. 29. Farrell PM, Rosenstein BJ, White TB, et al. Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic Fibrosis Foundation consensus report. J Pediatr 2008;153(2):S4-S14.

  30. 30. Habib AR, Kajbafzadeh M, Desai S, Yang CL, Skolnik K, Quon BS. A systematic review of the clinical efficacy and safety of CFTR modulators in cystic fibrosis. Sci Rep 2019;9:7234-7234.

  31. 31. Lieberman J, Rodbard S. Low blood pressure in young adults with cystic fibrosis: an effect of chronic salt loss in sweat? Ann Intern Med 1975;82:806-808.

  32. 32. Heijerman HG, McKone EF, Downey DG, et al. Efficacy and safety of the elexacaftor plus tezacaftor plus ivacaftor combination regimen in people with cystic fibrosis homozygous for the F508del mutation: a double-blind, randomised, phase 3 trial. Lancet 2019 October 31 (Epub ahead of print).

Citing Articles (726)

    Letters

    Figures/Media

      Visual Abstract Elexacaftor–Tezacaftor–Ivacaftor for Cystic Fibrosis
      Visual Abstract for 'Elexacaftor&#x2013;Tezacaftor&#x2013;Ivacaftor for Cystic Fibrosis with a Single Phe508del Allele,' P.G. Middleton and Others (10.1056/NEJMoa1908639)
    1. Demographic and Clinical Characteristics of the Patients at Baseline.*
      Demographic and Clinical Characteristics of the Patients at Baseline.
    2. Primary and Key Secondary Efficacy End Points.*
      Primary and Key Secondary Efficacy End Points.
    3. Absolute Change from Baseline in Percentage of Predicted FEV1, and Rate of Pulmonary Exacerbations.
      Absolute Change from Baseline in Percentage of Predicted FEV1, and Rate of Pulmonary Exacerbations.

      Panel A shows the absolute change from baseline in percentage of predicted forced expiratory volume in 1 second (FEV1), based on a mixed-effects model for repeated measures. Data are least-squares means, and 𝙸 bars indicate standard error of the mean; the dashed line indicates no change from baseline. Panel B shows a histogram of absolute change from baseline in percentage of predicted FEV1 through week 24, according to trial group. Panel C shows the overall estimated annualized rate of pulmonary exacerbations, the estimated annualized rate of pulmonary exacerbations leading to hospitalization, and the estimated annualized rate of pulmonary exacerbations treated with intravenous antibiotics. CI denotes confidence interval.

    4. Absolute Change from Baseline in Sweat Chloride Concentration and CFQ-R Respiratory Domain Score.
      Absolute Change from Baseline in Sweat Chloride Concentration and CFQ-R Respiratory Domain Score.

      Panel A shows the absolute change from baseline in sweat chloride concentration, based on a mixed-effects model for repeated measures; a reduction over time indicates improvement in CFTR function. Panel B shows a histogram of absolute change from baseline in sweat chloride concentration through week 24, according to trial group. Panel C shows the absolute change from baseline in the respiratory domain score on the Cystic Fibrosis Questionnaire–Revised (CFQ-R), based on a mixed-effects model for repeated measures. Scores are normalized to range from 0 to 100 points, with higher scores indicating a higher patient-reported quality of life with regard to respiratory symptoms; the minimum clinically important difference is 4 points. In Panels A and C, least-squares means at each visit are shown, and the 𝙸 bars indicate the corresponding standard error; the dashed line indicates no change from baseline.

    5. Adverse Events.*
      Adverse Events.