G551D Mutation

Trials 1 and 2 Overview: Patients With a G551D Mutation

KALYDECO (ivacaftor) was studied in two Phase 3 trials in patients with CF with a G551D mutation1

Additional Nomenclature9,10

CFTR mutations may also be known by their cDNA (Human Genome Variation Society) names.

G5515 Mutation

Trial Design1

  • Trials 1 and 2 were 48-week, Phase 3, randomized, double-blind, placebo-controlled trials in patients with CF and a G551D mutation
    • Trial 1: Patients 12 years of age and older (mean age 26 years; FEV1 40%-90% predicted at screening; mean FEV1 at baseline 64% predicted [range: 32% to 98%])
    • Trial 2: Patients 6 to 11 years of age (mean age 9 years; FEV1 40%-105% predicted at screening; mean FEV1 at baseline 84% predicted [range: 44% to 134%])
  • Patients received either KALYDECO 150 mg or placebo every 12 hours with fat-containing food, in addition to their prescribed CF therapies (e.g., tobramycin, dornase alfa) for 48 weeks. The use of inhaled hypertonic saline was not permitted

Primary Efficacy Endpoint1

The primary efficacy endpoint for both trials was improvement in lung function as determined by the mean absolute change from baseline in percent predicted FEV1 through Week 24 of treatment.

Selected Inclusion and Exclusion Criteria1

Selected Inclusion Criteria:

  • Confirmed CF diagnosis
  • G551D mutation
  • Aged ≥12 years (Trial 1);
    6-11 years (Trial 2)
  • Clinically stable
  • FEV1: 40%-90% predicted (Trial 1);
    40%-105% predicted (Trial 2)

Selected Exclusion Criteria:

  • Persistent infection with Burkholderia cenocepacia, Burkholderia dolosa, or Mycobacterium abscessus
  • Abnormal liver function

Other Efficacy Endpoints1

KALYDECO + prescribed cystic fibrosis therapy - trials’ endpoints

Primary Endpoint:

  • Change in FEV1 through Week 24

Other Efficacy Endpoints:

  • CFQ-R respiratory domain score
  • Time to first pulmonary exacerbation (Trial 1)
  • Body weight
  • Sweat chloride concentration

CFQ-R, Cystic Fibrosis Questionnaire-Revised.

Important Safety Information—
Serious Adverse Reactions

  • Serious adverse reactions, whether considered drug-related or not by the investigators, which occurred more frequently in patients treated with KALYDECO included abdominal pain, increased hepatic enzymes, and hypoglycemia

Please click here for additional Important Safety Information.

Indications and Usage

KALYDECO (ivacaftor) is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator indicated for the treatment of cystic fibrosis (CF) in patients age 2 years and older who have one of the following mutations in the CFTR gene: G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, or S549R.

KALYDECO is indicated for the treatment of CF in patients age 2 years and older who have an R117H mutation in the CFTR gene.

If the patient’s genotype is unknown, an FDA-cleared CF mutation test should be used to detect the presence of a CFTR mutation followed by verification with bi-directional sequencing when recommended by the mutation test instructions for use.

Limitation of Use:

KALYDECO is not effective in patients with CF who are homozygous for the F508del mutation in the CFTR gene.

Important Safety Information

Transaminase (ALT or AST) Elevations

  • Elevated transaminases have been reported in patients with CF receiving KALYDECO. Transaminase elevations were more common in patients with a history of transaminase elevations or in patients who had abnormal transaminases at baseline. It is recommended that ALT and AST be assessed prior to initiating KALYDECO, every 3 months during the first year of treatment, and annually thereafter. For patients with a history of transaminase elevations, more frequent monitoring of liver function tests should be considered
  • Patients who develop increased transaminase levels should be closely monitored until the abnormalities resolve. Dosing should be interrupted in patients with ALT or AST of greater than 5 times the upper limit of normal (ULN). Following resolution of transaminase elevations, consider the benefits and risks of resuming KALYDECO dosing

Concomitant Use with CYP3A Inducers

  • Use of KALYDECO with strong CYP3A inducers, such as rifampin, substantially decreases the exposure of ivacaftor, which may reduce the therapeutic effectiveness of KALYDECO. Co-administration of KALYDECO with strong CYP3A inducers, such as rifampin, rifabutin, phenobarbital, carbamazepine, phenytoin, and St. John’s wort is not recommended


  • Cases of non-congenital lens opacities/cataracts have been reported in pediatric patients treated with KALYDECO. Baseline and follow-up ophthalmological examinations are recommended in pediatric patients initiating KALYDECO treatment

Pediatric Use

  • The safety and efficacy of KALYDECO in patients with CF younger than 2 years of age have not been studied. The use of KALYDECO in children under the age of 2 years is not recommended

Serious Adverse Reactions

  • Serious adverse reactions, whether considered drug-related or not by the investigators, which occurred more frequently in patients treated with KALYDECO included abdominal pain, increased hepatic enzymes, and hypoglycemia

Adverse Reactions

  • The most common adverse reactions in patients with a G551D mutation in the CFTR gene (Trials 1 and 2) with an incidence of ≥8% and at a higher incidence for patients treated with KALYDECO (N=109) than for placebo (N=104) were headache (24% vs 16%), oropharyngeal pain (22% vs 18%), upper respiratory tract infection (22% vs 14%), nasal congestion (20% vs 15%), abdominal pain (16% vs 13%), nasopharyngitis (15% vs 12%), diarrhea (13% vs 10%), rash (13% vs 7%), nausea (12% vs 11%), and dizziness (9% vs 1%)
  • The safety profiles for patients with a G1244E, G1349D, G178R, G551S, G970R, S1251N, S1255P, S549N, or S549R mutation enrolled in Trial 4, for patients with an R117H mutation enrolled in Trial 5, and for patients ages 2 to less than 6 years enrolled in
    Trial 6 were similar to that observed in Trials 1 and 2

Click here to access full Prescribing Information for KALYDECO (ivacaftor).

References: 1. KALYDECO (ivacaftor) [prescribing information]. Boston, MA: Vertex Pharmaceuticals Incorporated; March 2015. 2. Ramsey BW, Davies J, McElvaney NG, et al; VX08-770-102 Study Group. A CFTR potentiator in patients with cystic fibrosis and the G551D mutation. N Engl J Med. 2011;365(18):1663-1672. 3. Davies JC, Wainwright CE, Canny GJ, et al; VX08-770-103 (ENVISION) Study Group. Efficacy and safety of ivacaftor in patients aged 6 to 11 years with cystic fibrosis with a G551D mutation. Am J Respir Crit Care Med. 2013;187(11):1219-1225. 4. Zielenski J. Genotype and phenotype in cystic fibrosis. Respiration. 2000;67(2):117-133. 5. Welsh MJ, Ramsey BW, Accurso F, Cutting GR. Cystic fibrosis: membrane transport disorders. In: Valle D, Beaudet A, Vogelstein B, et al, eds. The Online Metabolic & Molecular Bases of Inherited Disease. The McGraw-Hill Companies, Inc; 2004:part 21, chap 201. http://www.ommbid.com. Accessed February 25, 2016. 6. Welsh MJ, Smith AE. Molecular mechanisms of CFTR chloride channel dysfunction in cystic fibrosis. Cell. 1993;73(7):1251-1254. 7. Orenstein DM, Spahr JE, Weiner DJ. Cystic Fribrosis: A Guide for Patient and Family. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012. 8. Yu H, Burton B, Huang C-J, et al. Ivacaftor potentiation of multiple CFTR channels with gating mutations. J Cyst Fibros. 2012;11(3):237-245.
9. US CF Foundation, Johns Hopkins University. The Hospital for Sick Children. The Clinical and Functional TRanslation of CFTR (CFTR2). http://www.cftr2.org/index.php. Accessed February 25, 2016. 10. Berwouts S, Morris MA, Girodon E, Schwarz M, Stuhrmann M, Dequeker E. Mutation nomenclature in practice: findings and recommendations from the cystic fibrosis external quality assessment scheme. Hum Mutat. 2011;32(11):1197-1203. 11. US Department of Agriculture, Agricultural Research Service, Nutrient Data Laboratory Web site. ndb.nal.usda.gov/. Accessed February 25, 2016.

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