CLINICAL PHARMACOLOGY
Mechanism Of Action
Tezacaftor facilitates the cellular processing and trafficking of normal and select mutant forms of CFTR (including F508del-CFTR) to increase the amount of mature CFTR protein delivered to the cell surface. Ivacaftor is a CFTR potentiator that facilitates increased chloride transport by potentiating the channel-open probability (or gating) of the CFTR protein at the cell surface. For ivacaftor to function CFTR protein must be present at the cell surface. Ivacaftor can potentiate the CFTR protein delivered to the cell surface by tezacaftor, leading to a further enhancement of chloride transport than either agent alone. The combined effect of tezacaftor and ivacaftor is increased quantity and function of CFTR at the cell surface, resulting in increases in chloride transport.
CFTR Chloride Transport Assay In Fischer Rat Thyroid (FRT) Cells Expressing Mutant CFTR
The chloride transport response of mutant CFTR protein to tezacaftor/ivacaftor was determined in Ussing chamber electrophysiology studies using a panel of FRT cell lines transfected with individual CFTR mutations. The FRT assay was conducted in ivacaftor-responsive mutations and F508del mutation. Tezacaftor/ivacaftor increased chloride transport in FRT cells expressing CFTR mutations that result in CFTR protein being delivered to the cell surface.
The minimum response threshold was designated as a net increase of at least 10% of untreated normal over baseline. The tezacaftor/ivacaftor incubation resulted in either similar or increased chloride transport compared to ivacaftor alone. In vitro data may not accurately predict added clinical benefit of SYMDEKO (tezacaftor/ivacaftor combination) over KALYDECO (ivacaftor) alone for individual mutations. In addition, the magnitude of the net change over baseline in CFTR-mediated chloride transport is not correlated with the magnitude of clinical response for individual mutations.
Figure 1: Net Change Over Baseline (% of untreated normal) in CFTR-Mediated Chloride Transport Following Addition of SYMDEKO (Tezacaftor/Ivacaftor combination) in FRT Cells Expressing Mutant CFTR proteins (Ussing Chamber Electrophysiology Data)
*Clinical data exist for these mutations [see Clinical Studies].
#F508del represents data from one allele. A patient must have two copies of F508del mutation to be indicated for tezacaftor/ivacaftor (see Table 6).
Splice mutations cannot be studied in the FRT assay and are not included in Figure 1.
Table 6 lists responsive CFTR mutations based on (1) a clinical FEV1 response and/or (2) in vitro data in FRT cells, indicating that tezacaftor/ivacaftor increases chloride transport to at least 10% of untreated normal over baseline. CFTR gene mutations that are not responsive to ivacaftor alone are not expected to respond to SYMDEKO except for F508del homozygotes.
Table 6: List of CFTR Gene Mutations that Produce CFTR Protein and are Responsive to SYMDEKO
E56K | R117C | A455E | S945L | R1070W | 3272-26A→G |
P67L | E193K | F508del* | S977F | F1074L | 3849+10kbC→T |
R74W | L206W | D579G | F1052V | D1152H | |
D110E | R347H | 711+3A→G | K1060T | D1270N | |
D110H | R352Q | E831X | A1067T | 2789+5G→A | |
* A patient must have two copies of the F508del mutation or at least one copy of a responsive mutation presented in Table 6 to be indicated. |
Pharmacodynamics
Effects On Sweat Chloride
In Trial 1 (patients age 12 years and older who were homozygous for the F508del mutation), the treatment difference between SYMDEKO and placebo in mean absolute change from baseline in sweat chloride through Week 24 was -10.1 mmol/L (95% CI: -11.4, -8.8).
In Trial 2 (patients age 12 years and older who were heterozygous for the F508del mutation and a second mutation predicted to be responsive to tezacaftor/ivacaftor), the treatment difference in mean absolute change from baseline in sweat chloride through Week 8 was -9.5 mmol/L (95% CI: -11.7, -7.3) between SYMDEKO and placebo, and -4.5 mmol/L (95% CI: -6.7, -2.3) between ivacaftor and placebo.
In Trial 4 (patients age 6 to less than 12 years) a reduction in sweat chloride was observed from baseline through Week 4 and sustained throughout the 24-week treatment period. Mean absolute change in sweat chloride from baseline through Week 24 was -14.5 mmol/L (95% CI: -17.4, -11.6).
Cardiac Electrophysiology
At a dose 3 times the maximum approved recommended dose, tezacaftor does not prolong the QT interval to any clinically relevant extent.
In a separate study of ivacaftor evaluating doses up to 3 times the maximum approved recommended dose, ivacaftor does not prolong the QT interval to any clinically relevant extent.
Pharmacokinetics
The pharmacokinetics of tezacaftor and ivacaftor are similar between healthy adult volunteers and patients with CF. Following once-daily dosing of tezacaftor and twice-daily dosing of ivacaftor in patients with CF, plasma concentrations of tezacaftor and ivacaftor reach steady-state within 8 days and within 3 to 5 days, respectively, after starting treatment. At steady-state, the accumulation ratio is approximately 1.5 for tezacaftor and 2.2 for ivacaftor. Exposures of tezacaftor (administered alone or in combination with ivacaftor) increase in an approximately dose-proportional manner with increasing doses from 10 mg to 300 mg once daily. Key pharmacokinetic parameters for tezacaftor and ivacaftor at steady state are shown in Table 7.
Table 7: Mean (SD) Pharmacokinetic Parameters of Tezacaftor and Ivacaftor at Steady State in Patients with CF
| Drug | Cmax (mcg/mL) | Effective t½ (h) | AUCo-24h or AUCo-12h (mcg-h/mL)* |
Tezacaftor 100 mg once daily/ivacaftor 150 mg every 12 hours | Tezacaftor | 5.95 (1.50) | 15.0 (3.44) | 84.5 (27.8) |
Ivacaftor | 1.17 (0.424) | 13.7 (6.06) | 11.3 (4.60) |
* AUC0-24h for tezacaftor and AUC0-12h for ivacaftor |
Absorption
After a single dose in healthy subjects in the fed state, tezacaftor was absorbed with a median (range) time to maximum concentration (tmax) of approximately 4 hours (2 to 6 hours). The median (range) tmax of ivacaftor was approximately 6 hours (3 to 10 hours) in the fed state. When a single dose of tezacaftor/ivacaftor was administered with fat-containing foods, tezacaftor exposure was similar and ivacaftor exposure was approximately 3 times higher than when taken in a fasting state.
Distribution
Tezacaftor is approximately 99% bound to plasma proteins, primarily to albumin. Ivacaftor is approximately 99% bound to plasma proteins, primarily to alpha 1-acid glycoprotein and albumin. After oral administration of tezacaftor 100 mg once daily/ivacaftor 150 mg every 12 hours in patients with CF in the fed state, the mean (±SD) for apparent volume of distribution of tezacaftor and ivacaftor was 271 (157) L and 206 (82.9) L, respectively. Neither tezacaftor nor ivacaftor partition preferentially into human red blood cells.
Elimination
After oral administration of tezacaftor 100 mg once daily/ivacaftor 150 mg every 12 hours in patients with CF in the fed state, the mean (±SD) for apparent clearance values of tezacaftor and ivacaftor were 1.31 (0.41) and 15.7 (6.38) L/h, respectively. After steady-state dosing of tezacaftor in combination with ivacaftor in patients with CF, the effective half-lives of tezacaftor and ivacaftor were approximately 15 (3.44) and 13.7 (6.06) hours, respectively.
Metabolism
Tezacaftor is metabolized extensively in humans. In vitro data suggested that tezacaftor is metabolized mainly by CYP3A4 and CYP3A5. Following oral administration of a single dose of 100 mg 14C-tezacaftor to healthy male subjects, M1, M2, and M5 were the three major circulating metabolites of tezacaftor in humans. M1 has the similar potency to that of tezacaftor and is considered pharmacologically active. M2 is much less pharmacologically active than tezacaftor or M1, and M5 is not considered pharmacologically active. Another minor circulating metabolite, M3, is formed by direct glucuronidation of tezacaftor.
Ivacaftor is also metabolized extensively in humans. In vitro and in vivo data indicate that ivacaftor is metabolized primarily by CYP3A4 and CYP3A5. M1 and M6 are the two major metabolites of ivacaftor in humans. M1 has approximately one-sixth the potency of ivacaftor and is considered pharmacologically active. M6 is not considered pharmacologically active.
Excretion
Following oral administration of 14C-tezacaftor, the majority of the dose (72%) was excreted in the feces (unchanged or as the M2 metabolite) and about 14% was recovered in urine (mostly as M2 metabolite), resulting in a mean overall recovery of 86% up to 21 days after the dose. Less than 1% of the administrated dose was excreted in urine as unchanged tezacaftor, showing that renal excretion is not the major pathway of tezacaftor elimination in humans.
Following oral administration of ivacaftor alone, the majority of ivacaftor (87.8%) is eliminated in the feces after metabolic conversion. There was minimal elimination of ivacaftor and its metabolites in urine (only 6.6% of total radioactivity was recovered in the urine), and there was negligible urinary excretion of ivacaftor as unchanged drug.
Specific Populations
Based on population PK analyses, the PK exposure parameters of tezacaftor/ivacaftor in children and adolescents (ages 6 to <18 years) are similar to the AUCss range observed in adults when given in combination.
Pediatric Patients Age 6 To Less Than 12 Years
Table 8: Tezacaftor/ivacaftor exposure by age group, mean (SD)
Age Group | Dose | tezacaftor AUCss mcg•h/mL* | ivacaftor AUCss mcg•h/mL* |
6 to <12 years^ | | 71.3 (28.3) | 8.5 (3.34) |
6 to <12 years (<30 kg) | tezacaftor 50 mg/ ivacaftor 75 mg | 56.7 (22.3) | 6.92 (2.07) |
6 to <12 years (≥30 kg) A | tezacaftor 100 mg/ ivacaftor 150 mg | 92.7 (21.9) | 10.8 (3.52) |
^ Exposures in ≥30 kg weight range are predictions derived from the population PK model *AUC 0-24h for tezacaftor and AUC 0-12h for ivacaftor |
Pediatric Patients Age 12 To Less Than 18 Years
Following oral administration of SYMDEKO tablets, tezacaftor 100 mg once daily/ivacaftor 150 mg every 12 hours, the mean (±SD) AUCss for tezacaftor and ivacaftor was 97.1 (35.8) mcg•h/mL and 11.4 (5.50) mcg•h/mL, respectively, similar to the mean AUCss in adult patients administered SYMDEKO tablets, tezacaftor 100 mg once daily/ivacaftor 150 mg every 12 hours.
Patients With Hepatic Impairment
Following multiple doses of tezacaftor and ivacaftor for 10 days, patients with moderately impaired hepatic function (Child-Pugh Class B, score 7-9) had an approximately 36% increase in AUC and a 10% increase in Cmax for tezacaftor, and a 1.5-fold increase in ivacaftor AUC compared with healthy subjects matched for demographics. In a separate study, patients with moderately impaired hepatic function (Child-Pugh Class B, score 7-9) had similar ivacaftor Cmax, but an approximately 2.0-fold increase in ivacaftor AUC0-∞ compared with healthy subjects matched for demographics.
Pharmacokinetic studies have not been conducted in patients with mild (Child-Pugh Class A, score 5-6) or severe hepatic impairment (Child-Pugh Class C, score 10-15) receiving SYMDEKO. The magnitude of increase in exposure in patients with severe hepatic impairment is unknown, but is expected to be higher than that observed in patients with moderate hepatic impairment [see DOSAGE AND ADMINISTRATION, Use In Specific Populations, and Patient Counseling Information].
Patients With Renal Impairment
SYMDEKO has not been studied in patients with moderate or severe renal impairment (creatinine clearance ≤30 mL/min) or in patients with end-stage renal disease. In a human pharmacokinetic study with tezacaftor alone, there was minimal elimination of tezacaftor and its metabolites in urine (only 13.7% of total radioactivity was recovered in the urine with 0.79% as unchanged drug).
In a human pharmacokinetic study with ivacaftor alone, there was minimal elimination of ivacaftor and its metabolites in urine (only 6.6% of total radioactivity was recovered in the urine).
In population pharmacokinetic analysis, data from 665 patients on tezacaftor or tezacaftor in combination with ivacaftor in Phase 2/3 clinical trials indicated that mild renal impairment (N=147; eGFR 60 to less than 90 mL/min/1.73 m²) and moderate renal impairment (N=7; eGFR 30 to less than 60 mL/min/1.73 m²) did not affect the clearance of tezacaftor significantly [see Use In Specific Populations].
Male And Female Patients
The pharmacokinetic parameters of tezacaftor and ivacaftor are similar in males and females.
Drug Interactions Studies
Drug interaction studies were performed with SYMDEKO and other drugs likely to be co-administered or drugs commonly used as probes for pharmacokinetic interaction studies [see DRUG INTERACTIONS].
Potential For Tezacaftor/Ivacaftor To Affect Other Drugs
Clinical studies (with rosiglitazone and desipramine – see Table 9) showed that ivacaftor is not an inhibitor of CYP2C8 or CYP2D6. Based on in vitro results, ivacaftor has the potential to inhibit CYP3A and P-gp, and may also inhibit CYP2C9. In vitro, ivacaftor was not an inducer of CYP isozymes. Ivacaftor is not an inhibitor of transporters OATP1B1, OATP1B3, OCT1, OCT2, OAT1, or OAT3.
Based on in vitro results, tezacaftor has a low potential to inhibit CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. Tezacaftor has a low potential to induce CYP3A, but it is not an inducer of CYP1A2 and CYP2B6. Tezacaftor has a low potential to inhibit transporters P-gp, BCRP, OATP1B3, OCT2, OAT1, or OAT3.
Clinical studies with midazolam showed that SYMDEKO is not an inhibitor of CYP3A. Co-administration of SYMDEKO with digoxin, a sensitive P-gp substrate, increased digoxin exposure by 1.3-fold. Co-administration of SYMDEKO with an ethinyl estradiol/ norethindrone oral contraceptive had no significant effect on the exposures of the hormonal contraceptives. Co-administration of SYMDEKO with pitavastatin, an OATP1B1 substrate, had no clinically relevant effect on the exposure of pitavastatin.
The effects of tezacaftor and ivacaftor (or ivacaftor alone) on the exposure of co-administered drugs are shown in Table 9 [see DRUG INTERACTIONS].
Potential For Other Drugs To Affect Tezacaftor/Ivacaftor
In vitro studies showed that ivacaftor and tezacaftor were substrates of CYP3A enzymes (i.e., CYP3A4 and CYP3A5). Exposure to ivacaftor and tezacaftor will be reduced by concomitant CYP3A inducers and increased by concomitant CYP3A inhibitors.
In vitro studies showed that tezacaftor is a substrate for the uptake transporter OATP1B1, and efflux transporters P-gp and BCRP. Tezacaftor is not a substrate for OATP1B3. In vitro studies showed that ivacaftor is not a substrate for OATP1B1, OATP1B3, or P-gp.
The effects of co-administered drugs on the exposure of tezacaftor and ivacaftor (or ivacaftor alone) are shown in Table 10 [see DOSAGE AND ADMINISTRATION and DRUG INTERACTIONS].
Table 9: Impact of Tezacaftor/Ivacaftor or Ivacaftor on Other Drugs
Drug | Dose and Schedule | Effect on Drug PK | Mean Ratio (90% CI) of Other Drugs No Effect=1.0 |
Dose | TEZ/IVA or IVA | AUC | Cmax |
Midazolam | 2 mg single oral dose | TEZ 100 mg/IVA 150 mg every morning + IVA 150 mg every evening | ↔Midazolam | 1.12 (1.01, 1.25) | 1.13 (1.01, 1.25) |
Digoxin | 0.5 mg single dose | TEZ 100 mg/IVA 150 mg every morning + IVA 150 mg every evening | ↑ Digoxin | 1.30 (1.17, 1.45) | 1.32 (1.07, 1.64) |
Oral Contraceptive | Ethinyl estradiol/ Norethindrone 0.035 mg/1.0 mg once daily | TEZ 100 mg/IVA 150 mg every morning + IVA 150 mg every evening | ↔ Ethinyl estradiol | 1.12 (1.03, 1.22) | 1.15 (0.99, 1.33) |
↔ Norethindrone | 1.05 (0.98, 1.12) | 1.01 (0.87, 1.19) |
Pitavastatin | 2 mg single dose | TEZ 100 mg/IVA 150 mg every morning + IVA 150 mg every evening | ↑ Pitavastatin* | 1.24 (1.17, 1.31) | 0.977 (0.841, 1.14) |
Rosiglitazone | 4 mg single oral dose | IVA 150 mg twice daily | ↔ Rosiglitazone | 0.975 (0.897, 1.06) | 0.928 (0.858, 1.00) |
Desipramine | 50 mg single dose | IVA 150 mg twice daily | ↔ Desipramine | 1.04 (0.985, 1.10) | 1.00 (0.939; 1.07) |
↑ = increase, ↓ = decrease, ↔ = no change. CI = Confidence interval; TEZ = tezacaftor; IVA = ivacaftor; PK = Pharmacokinetics * Effect is not clinically significant – no dose adjustment is necessary |
Table 10: Impact of Other Drugs on Tezacaftor/Ivacaftor or Ivacaftor
Drug | Dose and Schedule | Effect on TEZ/IVA PK | Mean Ratio (90% CI) of Tezacaftor and Ivacaftor No Effect = 1.0 |
Dose | TEZ/IVA or IVA | AUC | Cmax |
Itraconazole | 200 mg twice a day on Day 1, followed by 200 mg once daily | TEZ 25 mg + IVA 50 mg once daily | ↑Tezacaftor | 4.02 (3.71, 4.63) | 2.83 (2.62, 3.07) |
↑Ivacaftor | 15.6 (13.4, 18.1) | 8.60 (7.41, 9.98) |
Ciprofloxacin | 750 mg twice daily | TEZ 50 mg + IVA 150 mg twice daily | ↔Tezacaftor | 1.08 (1.03, 1.13) | 1.05 (0.99, 1.11) |
↑ Ivacaftor* | 1.17 (1.06, 1.30) | 1.18 (1.06, 1.31) |
Oral Contraceptive | Norethindrone/ethinyl estradiol 1.0 mg/0.035 mg once daily | TEZ 100 mg/IVA 150 mg every morning + IVA 150 mg every evening | ↔ Tezacaftor | 1.01 (0.963, 1.05) | 1.01 (0.933, 1.09) |
↔ Ivacaftor | 1.03 (0.960, 1.11) | 1.03 (0.941, 1.14) |
Rifampin | 600 mg once daily | IVA 150 mg single dose | ↓ Ivacaftor | 0.114 (0.097, 0.136) | 0.200 (0.168, 0.239) |
Fluconazole | 400 mg single dose on Day 1, followed by 200 mg once daily | IVA 150 mg twice daily | ↑Ivacaftor | 2.95 (2.27, 3.82) | 2.47 (1.93, 3.17) |
↑ = increase, ↓ = decrease, ↔ = no change. CI = Confidence interval; TEZ = tezacaftor; IVA = ivacaftor; PK = Pharmacokinetics * Effect is not clinically significant – no dose adjustment is necessary |
Clinical Studies
Dose Ranging
Dose selection for the clinical program primarily consisted of one double-blind, placebo-controlled, multiple-cohort trial which included 176 patients with CF (homozygous for the F508del mutation) 18 years of age and older with a screening ppFEV1≥40. In the study, 34 and 106 patients, respectively, received tezacaftor at once-daily doses of 10 mg, 30 mg, 100 mg, or 150 mg alone or in combination with ivacaftor 150 mg q12h, and 33 patients received placebo. During the 28-day treatment period, dose-dependent increases in mean ppFEV1 change from baseline were observed with tezacaftor in combination with ivacaftor. Tezacaftor/ivacaftor in general had a greater mean treatment effect than tezacaftor alone. No additional benefit was observed at tezacaftor doses greater than 100 mg daily.
Efficacy
The efficacy of SYMDEKO in patients with CF age 12 years and older was evaluated in three Phase 3, double-blind, placebo-controlled trials (Trials1, 2, and 3).
Trial 1 was a 24-week randomized, double-blind, placebo-controlled, two-arm study in patients with CF who were homozygous for the F508del mutation in the CFTR gene.
Trial 2 was a randomized, double-blind, placebo-controlled, 2-period, 3-treatment, 8-week crossover study in patients with CF who were heterozygous for the F508del mutation and a second mutation predicted to be responsive to tezacaftor/ivacaftor. Mutations predicted to be responsive were selected for the study based on the clinical phenotype (pancreatic sufficiency), biomarker data (sweat chloride), and in vitro responsiveness to tezacaftor/ivacaftor [see Clinical Studies]. Patients were randomized to and received sequences of treatment that included SYMDEKO, ivacaftor, and placebo.
Trial 3 was a 12-week randomized, double-blind, placebo-controlled, two-arm study in patients with CF who were heterozygous for the F508del mutation and a second CFTR mutation predicted to be unresponsive to tezacaftor/ivacaftor. Mutations predicted to be non-responsive were selected for the study based on biologic plausibility (mutation class), clinical phenotype (pancreatic insufficiency), biomarker data (sweat chloride), and in vitro testing to tezacaftor and/or ivacaftor.
Patients in all trials continued on their standard-of-care CF therapies (e.g., bronchodilators, inhaled antibiotics, dornase alfa, and hypertonic saline) and were eligible to roll over into a 96-week open-label extension. Patients had a ppFEV1 at screening between 40-90%. Patients with a history of colonization with organisms associated with a more rapid decline in pulmonary status such as Burkholderia cenocepacia, Burkholderia dolosa, or Mycobacterium abscessus, or who had 2 or more abnormal liver function tests at screening (ALT, AST, AP, GGT ≥3 x ULN or total bilirubin ≥2 x ULN) or AST or ALT ≥5 x ULN, were excluded from the trials.
Trial In Patients With CF Who Were Homozygous For The F508del Mutation In The CFTR Gene (Trial 1)
Trial 1 evaluated 504 patients (248 SYMDEKO, 256 placebo) with CF age 12 years and older (mean age 26.3 years). The mean ppFEV1 at baseline was 60.0% (range: 27.8% to 96.2%). The primary efficacy endpoint was change in lung function as determined by absolute change from baseline in ppFEV1 through Week 24. Treatment with SYMDEKO resulted in a statistically significant improvement in ppFEV1. The treatment difference between SYMDEKO and placebo for the mean absolute change in ppFEV1 from baseline through Week 24 was 4.0 percentage points (95% CI: 3.1, 4.8; P<0.0001). These changes persisted throughout the 24-week treatment period (Figure 2). Improvements in ppFEV1 were observed regardless of age, sex, baseline ppFEV1, colonization with Pseudomonas, concomitant use of standard-of-care medications for CF, and geographic region.
Key secondary efficacy variables included relative change from baseline in ppFEV1 through Week 24; number of pulmonary exacerbations from baseline through Week 24; absolute change in BMI from baseline at Week 24, and absolute change in CFQ-R Respiratory Domain Score (a measure of respiratory symptoms relevant to patients with CF, such as cough, sputum production, and difficulty breathing) from baseline through Week 24. For the purposes of this trial, a pulmonary exacerbation was defined as a change in antibiotic therapy (IV, inhaled, or oral) as a result of 4 or more of 12 pre-specified sino-pulmonary signs/symptoms. See Table 11 for a summary of key secondary outcomes in Trial 1.
Table 11: Key Secondary Efficacy Analyses, Full Analysis Set (Trial 1)*
| | Placebo N=256 | SYMDEKO N=248 |
Relative change in ppFEV1 from baseline through Week 24 (%) | Treatment difference (95% CI) P value | NA | 6.8 (5.3, 8.3) P<0.0001† |
Number of pulmonary exacerbations from baseline through Week 24 | Number of events (event rate per year‡) Rate ratio (95% CI) P value | 122 (0.99) NA | 78 (0.64) 0.65 (0.48, 0.88) P=0.0054† |
Absolute change in BMI from baseline at Week 24 (kg/m²) | Treatment difference (95% CI) | - | 0.06 (-0.08, 0.19) |
Absolute change in CFQ-R Respiratory Domain Score from baseline through Week 24 (points) | Treatment difference (95% CI) | - | 5.1 (3.2, 7.0) |
BMI: body mass index; CI: confidence interval; CFQ-R: Cystic Fibrosis Questionnaire-Revised; IVA: ivacaftor; NA: not applicable; ppFEV1: percent predicted forced expiratory volume in 1 second; * A hierarchical testing procedure was performed for primary and secondary endpoints vs placebo; at each step, P≤0.05 and all previous tests also meeting this level of significance were required for statistical significance. † Indicates statistical significance confirmed in the hierarchical testing procedure. Other efficacy measures considered not statistically significant. ‡ Estimated event rate per year calculated using 48 weeks per year. |
Figure 2: Absolute Change From Baseline in Percent Predicted FEV1 at Each Visit in Trial 1
Trial In Patients With CF Who Were Heterozygous For The F508del Mutation And A Second Mutation Predicted To Be Responsive To Tezacaftor/Ivacaftor (Trial 2)
Trial 2 evaluated 244 patients with CF age 12 years and older (mean age 34.8 years). The mean ppFEV1 at baseline was 62.3% (range: 34.6 to 93.5). Of the 244 patients included in the efficacy analysis, 146 patients had a splice mutation and 98 patients had a missense mutation as the second allele. 161 patients received SYMDEKO, 156 patients received ivacaftor, and 161 patients received placebo. The primary efficacy endpoint was the mean absolute change from study baseline in percent predicted FEV1 averaged at Weeks 4 and 8 of treatment. The key secondary efficacy endpoint was absolute change in CFQ-R Respiratory Domain Score from study baseline averaged at Weeks 4 and 8 of treatment. For the overall population, treatment with SYMDEKO compared to placebo resulted in significant improvement in ppFEV1 (6.8 percentage points [95% CI: 5.7, 7.8]; P<0.0001) and CFQ-R Respiratory Domain Score (11.1 points (95% CI 8.7, 13.6); P<0.0001). Treatment difference for ppFEV1 between ivacaftor-and placebo-treated patients was 4.7 percentage points (95% CI: 3.7, 5.8; P<0.0001) and 2.1 percentage points (95% CI: 1.2, 2.9; P<0.0001) between SYMDEKO-and ivacaftor-treated patients, which were statistically significant. Improvements in ppFEV1 were observed regardless of age, baseline ppFEV1, sex, mutation class, colonization with Pseudomonas, concomitant use of standard-of-care medications for CF, and geographic region. Statistically significant improvements compared to placebo were also observed in the subgroup of patients with splice mutations and missense mutations (Table 12).
Table 12: Effect of SYMDEKO for Efficacy Variables in Splice and Missense CFTR Mutation Subgroups
Mutation (n) | Absolute Change inpercent predicted FEV 1*† | Absolute Change in CFQ-R Respiratory Domain Score (Points)*‡ | Absolute Change in Sweat Chloride (mmol/L)*‡ |
Splice mutations (n= 93 for TEZ/IVA, n=97 for PBO) Results shown as difference in mean (95% CI) change from study baseline for SYMDEKO vs. placebo-treated patients: |
| 7.4 (6.0, 8.7) | 9.5 (6.3, 12.7) | -5.4 (-8.0, -2.7) |
By individual splice mutation (n). Results shown as mean (minimum, maximum) for change from study baseline for SYMDEKO-treated patients |
2789+5G→A (25) | 8.6 (-1.5, 23.4) | 12.0 (-8.3, 38.9) | -3.2 (-16.5, 9.0) |
3272-26A→G (23) | 5.7 (-2.1, 25.9) | 5.7 (-22.2, 44.4) | -3.8 (-22.3, 16.5) |
3849+10kBc→T (43) | 5.8 (-7.2, 22.3) | 8.2 (-25.0, 47.2) | -5.6 (-27.0, 8.5) |
711+3A→G (2) | 4.3 (2.0, 6.7) | -4.2 (-5.6, -2.8) | -15.4 (-21.0, -9.8) |
E831X§ (0) | NA | NA | NA |
Missense mutations (n=66 for TEZ/IVA, n=63 for PBO) Results shown as difference in mean (95% CI) change from study baseline for SYMDEKO vs. placebo-treated patients: |
| 5.9 (4.2, 7.5) | 13.4 (9.6, 17.3) | -16.3 (-19.7, -12.9) |
By individual missense mutation (n). Results shown as mean (minimum, maximum) for change from study baseline for SYMDEKO-treated patients |
D579G (2) | 8.1 (-0.2, 16.4) | 11.1 (5.6, 16.7) | -23.1 (-24.8, -21.5) |
D110H (1) | -1.0 (-1.0, -1.0) | -11.1 (-11.1, -11.1) | -22.5 (-22.5, -22.5) |
D1152H (21) | 3.8 (-2.5, 12.5) | 15.2 (-8.3, 55.6) | -4.1 (-15.0, 11.5) |
A455E (11) | 8.5 (2.6, 16.1) | 11.6 (-11.1, 44.4) | -0.3 (-8.8, 14.0) |
L206W (4) | 3.0 (-4.5, 10.2) | 12.5 (-2.8, 38.9) | -36.1 (-44.5, -27.5) |
P67L (11) | 9.4 (0.0, 31.9) | 11.7 (-12.5, 72.2) | -29.3 (-50.0, 0.8) |
R1070W (2) | 6.1 (2.0, 10.1) | 29.2 (16.7, 41.7) | -13.8 (-26.8, -0.8) |
R117C (1) | 2.9 (2.9, 2.9) | 16.7 (16.7, 16.7) | -38.8 (-38.8, -38.8) |
R347H (2) | -0.5 (-2.8, 1.7) | 5.6 (-5.6, 16.7) | -13.8 (-19.0, -8.5) |
R352Q (2) | 4.9 (2.6, 7.1) | 8.3 (8.3, 8.3) | -43.3 (-49.8, -36.8) |
S945L (7) | 9.6 (0.7, 19.5) | 11.3 (-4.2, 25.0) | -29.0 (-42.5, -8.0) |
S977F (2) | 10.1 (5.5, 14.7) | -1.4 (-8.3, 5.6) | -13.9 (-22.3, -5.5) |
(n=) patient numbers analysed *Average of Week 4 and 8 values † Absolute change in ppFEV1 by individual mutations is an ad hoc analysis. ‡ Absolute change in CFQ-R Respiratory Domain Score and absolute change in sweat chloride by mutation subgroups and by individual mutations are ad hoc analyses. § Patients enrolled did not receive tezacaftor/ivacaftor treatment. |
In an analysis of BMI at Week 8, an exploratory endpoint, patients treated with SYMDEKO had a mean improvement of 0.2 kg/m² (95% CI [0.0, 0.3]), 0.1 kg/m² (95% CI [-0.1, 0.3]), and 0.3 kg/m² (95% CI [0.1, 0.5]) versus placebo for the overall, splice, and missense mutation populations of patients, respectively.
Trial In Patients With CF Who Were Heterozygous For The F508del Mutation And A Second Mutation Not Predicted To Be Responsive To Tezacaftor/Ivacaftor (Trial 3)
Trial 3 evaluated 168 patients with CF (83 SYMDEKO and 85 placebo) age 12 years and older (mean age 26.1 years) who were heterozygous for the F508del mutation and had a second CFTR mutation predicted to be unresponsive to tezacaftor/ivacaftor. CF patients with the F508del mutation and one of the following mutations in the CFTR gene were enrolled in the study (listed in decreasing frequency): W1282X, G542X, N1303K, 621+1G>T, 1717-1G>A, 1898+1G>A, CFTRdele2,3, 2183delAA>G, 2184insA, R1162X, R553X, 3659delC, 3905insT, G970R, I507del, R1066C, R347P, 1154insTC, 1811+1.6kbA>G, 2184delA, 405+1G>A, E60X, G85E, L1077P, Q39X, S466X, Y1092X, 1078delT, 1248+1G>A, 1677delTA, 1812-1G>A, 2869INSG, 3120+1G>A, 394delTT, 457TAT>G, 711+1G>T, 711+5G>A, 712-1G>T, G673x, L1065P, Q220X, Q493X, R709X, V520F. The mean ppFEV1 at baseline was 57.5% [range: 31.0 to 96.7]. The primary efficacy endpoint was change from baseline in absolute ppFEV1 through Week 12. The overall treatment difference between SYMDEKO and placebo for the mean absolute change in ppFEV1 from baseline through Week 12 was 1.2 percentage points (95% CI: -0.3, 2.6). This study was terminated following the planned interim analysis because the pre-specified futility criteria were met.