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Published in final edited form as: Pulm Pharmacol Ther. 2024 Jul 2;86:102314. doi: 10.1016/j.pupt.2024.102314

Differential distribution of ivacaftor and its metabolites in plasma and human airway epithelia

Zhongyu Liu 1, Justin D Anderson 1, Natalie R Rose 1, Elizabeth H Baker 2, Alexander E Dowell 3, Kevin J Ryan 3, Edward P Acosta 3, Jennifer S Guimbellot 1,4,*
PMCID: PMC12499601  NIHMSID: NIHMS2014393  PMID: 38964603

Abstract

Ivacaftor is the first clinically approved monotherapy potentiator to treat CFTR channel dysfunction in people with cystic fibrosis. Ivacaftor (Iva) is a critical component for all current modulator therapies, including highly effective modulator therapies. Clinical studies show that CF patients on ivacaftor-containing therapies present various clinical responses, off-target effects, and adverse reactions, which could be related to metabolites of the compound. In this study, we reported the concentrations of Iva and two of its major metabolites (M1-Iva and M6-Iva) in capillary plasma and estimated M1-Iva and M6-Iva metabolic activity via the metabolite parent ratio in capillary plasma over 12 hours. We also used the ratio of capillary plasma versus human nasal epithelial cell concentrations to evaluate entry into epithelial cells in vivo. M6-Iva was rarely detected by LC-MS/MS in epithelial cells from participants taking ivacaftor, although it was detected in plasma. To further explore this discrepancy, we performed in vitro studies, which showed that M1-Iva, but not M6-Iva, readily crossed 16HBE cell membranes. Our studies also suggest that metabolism of these compounds is unlikely to occur in airway epithelia despite evidence of expression of metabolism enzymes. Overall, our data provide evidence that there are differences between capillary and cellular concentrations of these compounds that may inform future studies of clinical response and off-target effects.

Keywords: Cystic fibrosis, Ivacaftor, M1-Iva, M6-Iva, CYP3A, human airway epithelia

1. Introduction

Cystic fibrosis (CF) is an autosomal-recessive, multi-organ, chronic life-limiting genetic disease caused by genetic variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. In the past decade, highly effective modulator therapy (HEMT) has become available for over 90% of people with CF (pwCF) over age 2 years, and has dramatically improved pulmonary symptoms and quality of life for many individuals in this population. (1, 2) Ivacaftor (Iva) was the first clinically approved modulator in HEMT and is a critical component of all modulator therapies currently available, serving as a potentiator to improve chloride channel opening. (1, 3) Prior reports showed that ivacaftor accumulates in vitro in epithelia, suggesting the need for concentration quantitation to optimize dosing and reduce adverse effects. (4) Less evidence of Iva pharmacokinetics exists in vivo, which may influence the applicability of in vitro studies to human disease. Detailed knowledge of the distribution of modulators and their metabolites in plasma and target tissues is necessary as modulator eligibility and use continue to be expanded.

Cytochrome P450 3A (CYP3A) isozymes are involved in up to 60% of all drug metabolism in vivo. (5) CYP3A 4 and 5 isoforms are the main cytochrome P450 enzymes that metabolize Iva and other modulator compounds. (6–8) Iva is converted to 11 metabolites, with the two dominant metabolites in humans being M1-Iva and M6-Iva. (9–13) Most CYP3A metabolism likely occurs in hepatocytes and enterocytes, but CYP3A enzymes are also expressed in airway epithelial cells whose contribution to metabolism is not well known. An additional member of this isozyme family, CYP3A7, can be found in liver and extra-hepatic tissue. All members of the CYP3A family have similar substrates, but their role in metabolizing Iva and other modulators has not been fully established. (14–18) M1-Iva and M6-Iva have potentiation activity (1/6 and 1/50 that of Iva, respectively) but the concurrent impact of both metabolites in target tissue has not been determined. (7) We previously reported high venous plasma concentrations of both M1-Iva (Cavg = 3156 ng/mL) and M6-Iva (Cavg = 3821 ng/mL) in pwCF, while only M1-Iva was routinely detected in nasal brushings lysate samples (mean 696 ng/mL). (19)

Drug metabolites have the potential to influence drug response, such as complementing or competing with the parent compound, causing off-target effects, or influencing the development of side effects, such as adverse drug reactions (ADRs), which are not always identified during clinical trials. These aspects of Iva and its metabolites are important to study during post-marketing evaluations. (20) Early studies showed that Iva and its metabolites, M1-Iva and M6-Iva, have the potential to inhibit CYP enzymes and P glycoproteins (P-gp). (21, 22) Additional early studies of Iva and its metabolites indicated no induction or inhibition of CYP enzymes, but showed potential effects on transporters. (10–13) In vitro, a CYP enzyme activity study showed that Iva and M1-Iva reduce CYP3A4 activity, especially M1-Iva, which has stronger inhibition. M6-Iva can induce CYP3A4 activity. (23) Other studies have shown that Iva can influence ion channels, such as ligand-gated ion channels in the central nervous system, (24–26) which are hypothesized to cause adverse neuropsychiatric effects seen in people on CFTR modulators. Iva possesses a significant affinity for the 5-hydroxytryptamine (5-HT; serotonin) 5-HT2C receptor, β3-adrenergic receptor, δ-opioid receptor, and the dopamine transporter, suggesting that it may have effects on the central nervous system. (25) In addition, Iva and its metabolites may be related to reported adverse effects such as headache, upper respiratory tract infection, nasal congestion, rash, and dizziness. (9–13, 27, 28) Therefore, further investigations both in vitro and in vivo should be considered to determine if Iva and its metabolites have off target binding that may contribute to a patient’s clinical response and potential adverse effects. In this study, we report in vivo capillary and cellular concentrations of Iva and its metabolites, which expands upon our previous work. (19) We also report in vitro studies of the major human metabolites M1-Iva and M6-Iva to better understand their disposition.

2. Materials and Methods

2.1. Human subjects and ethical approvals

Human subjects (both CF and non-CF) were enrolled in this study as previously described. (19, 29–31) Patients were recruited and consented following approved UAB protocols (IRB-300001194 and IRB-151030001). Biorepository samples were used under a separately approved research protocol (IRB-300002963).

2.2. Collection of samples

Participants were taking their clinically prescribed dose of ivacaftor (150mg twice daily) for at least two weeks prior to sampling to ensure steady-state concentrations. Venous blood was collected via phlebotomy and processed for plasma as previously described. (19) Capillary samples were collected via fingerstick into lithium heparin capillary blood collection tubes and processed for plasma which was immediately frozen at −80°C until quantitation. Human nasal epithelial cells (HNEs) were collected using a cytology brush biopsy (sterile 5 mm cytobrush, Medical Packaging Corp., Panorama, CA). Cells were dissociated with Accutase (STEMCELL technologies 07920, Vancouver, BC, V6A 1B6, Canada) into a single cell suspension with pipetting. Cells were washed and counted, lysed with NP-40 lysis buffer (Invitrogen™ FNN0021, Waltham, MA) and immediately frozen at −80°C until analysis using liquid chromatography with tandem mass spectrometry (LC-MS/MS) developed according to the Food and Drug Administration (FDA) standards. (32) Cells for culture were also dissociated with Accutase, counted, and seeded into flasks as described below.

2.3. Cell culture

Primary HNEs were collected from CF and non-CF volunteers and primary human bronchial epithelial cells (HBEs) were obtained from CF patients’ lung explants similarly to previously described methods. (33) (34) In brief, both HNE and HBE cells were seeded in a flask with irradiated 3T3 feeder fibroblasts and cultured for 7–14 days for conditional reprogramming to promote proliferation. Once epithelial cells were confluent, primary HNEs, HBEs, 16HBE, or CFBE cell line cells were seeded into 6.5 mm transwells (Corning™ 3470, Corning, Kennebunk, ME, USA) with 0.4 μm membrane in a 24-well plate with density of 0.75–1.5X105 cells/well. Cells were cultured at air-liquid interface (ALI) until cells formed a tight monolayer without leaking after apical fluid was removed. An immortalized bronchial epithelial cell line (16HBEs) and cystic fibrosis bronchial epithelial cells (CFBEs) were obtained as a generous gift from Cystic Fibrosis Foundation. Cells were grown in Eagle’s Minimal Essential Medium (EMEM) (35) for experimentation.

2.4. Cell treatments

Primary HNEs, HBEs, and CFBEs were seeded and cultured in transwells for two days. Media was removed from the apical side and cells were fed from the basolateral side for ALI culture. Primary HNEs and HBEs were cultured at ALI for three weeks and CFBEs were cultured at ALI for three days. Following differentiation, ALI cultures were treated with 1 μM of ivacaftor (Selleckchem S1144, Houston, TX, USA) in basolateral media for 48 hours, washed twice with PBS, and lysed with 150 μl of NP40 lysis buffer per transwell filter. Cellular lysate was used to quantify intracellular concentration of ivacaftor and ivacaftor metabolites (M1-Iva, and M6-Iva) using LC-MS/MS. 16HBEs were seeded and cultured in transwells for two days followed by ALI culture for three days. 16HBE cells were treated with M1-Iva (hydroxymethyl ivacaftor, ClearSynth CS-O-11850, Brampton, Ontario L6X 1A4, CA) or M6-Iva (ivacaftor carboxylate, ClearSynth CS-O-11851, Brampton, Ontario L6X 1A4, CA) in basolateral media for 48 hours. Cells were subsequently lysed with 150 μl of NP40 lysis buffer per transwell filter.

2.5. Statistical analysis

Data were calculated and analyzed with GraphPad Prism 10 (San Diego, CA) and Stata 18 software (College Station, TX). Standard error of the mean (SEM) was used to present the variability of the data. Student’s t-tests were used to compare the differences between two groups. Mixed-effects analysis with the Geisser-Greenhouse correction was used to assess changes in MPR over time. P values <0.05 were considered statistically significant.

3. Results

3.1. Qualitative analysis of Iva and its known metabolites in plasma and cellular lysates by LC-MS/MS.

In our prior study (19), only M1-Iva and Iva were identified in cellular lysates despite high concentrations of M1-Iva, Iva, and M6-Iva in the plasma. We hypothesized that there may be some differences in the metabolites produced in the tissue and thus performed a qualitative assessment of other potential human metabolites that could influence CFTR activity or other effects on toxicity, cell metabolism, or transport. (10–13, 19) While we were not able to assess for all possible metabolites, we were able to further evaluate ivacaftor M3 (MW 599.100), ivacaftor hydrate (MW 411.100), ivacaftor benzenesulfonate (MW 551.100), as well as the predominant compounds M6-Iva, M1-Iva, and Iva. Representative chromatographs of these metabolites are shown for lysate (Figure 1A) and matched plasma (Figure 1B) from the same individual collected at the same time. Additional peaks for M3-Iva and Iva-hydrate in plasma were noted, but other metabolite peaks in lysate were not observed.

Figure 1. Representative chromatographs of Iva and metabolites in cellular lysate (A) and plasma (B).

Figure 1.

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To assess if there were any other potential metabolites in the blood and nasal epithelial cells, we designed a qualitative assessment for all known metabolites for which the molecular weight could be determined (including M3-Iva, Iva-hydrate, Iva benzenesulfonate, M1-Iva, M6-Iva, and the parent compound Iva). We detected primarily Iva, M1-Iva, and M6-Iva, as described previously. (10) In plasma, we also detected small peaks of Iva-hydrate and M3-Iva. We detected no other significant peaks in the cellular lysate.

3.2. Concentrations of Iva, M1-Iva, and M6-Iva in capillary plasma are lower than previously reported for venous blood.

In our prior publication, we assessed real-world pharmacokinetics of Iva in pwCF. (19, 32) The patient demographics and baseline clinical characteristics have been described for all study participants; however, the capillary plasma data, including a comprehensive assessment of metabolite production, have not been reported. As modulator use has expanded to dual and triple combination therapy (10–13), additional evidence of side effects have been observed. (36–40) Because side effects may be related to either the parent compound or metabolites, we evaluated concentrations of Iva, M1-Iva, and M6-Iva in plasma, with a focus on capillary plasma to measure concentrations that most closely approximate what is delivered to the peripheral tissues (Figure 2). Non-compartmental pharmacokinetic analysis of the capillary blood concentrations revealed overall lower compound exposure (Table 1). (19) The concentration ranges in capillary plasma were 438 – 728 ng/ml (Iva); 604 – 1076 ng/ml (M1-Iva); and 700 – 955 ng/ml (M6-Iva).

Figure 2. In vivo concentrations of Iva, M1-Iva, and M6-Iva.

Figure 2.

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Mean concentrations of compounds in plasma samples from people with CF derived from capillary and venous sample collection over a 12 hour time period. A Iva, B M1-Iva, C M6-Iva. All data were from 11 participants of study at visit 1. Venous concentrations are derived from previously reported data (19) and are shown for comparison. Error bars represent standard error of the mean (SEM).

Table 1.

Non-compartmental analysis of the capillary blood concentrations.

Iva (n = 8) Iva-M1 (n = 8) Iva-M6 (n = 8)
Mean (SD) Median (min, max) CV (%) Mean (SD) Median (min, max) CV (%) Mean (SD) Median (min, max) CV(%)
Cmin (ng/mL) 352 (245) 287 (113, 813) 70 501 (228) 475 (55, 839) 57 522 (365) 527 (5.8, 1070) 70
Cmax (ng/mL) 744 (429) 552 (373, 1550) 58 1036 (520) 913 (402, 1750) 50 927 (456) 918 (265, 1630) 49
Cavg (ng/mL) 532 (343) 416(221, 1206) 65 726 (365) 607 (256, 1170) 50 797 (430) 842 (231, 1418) 54
Tmax (h) 5 (0.76) 5 (4, 6) 15 5.3 (0.7) 5 (4, 6) 13 6.9 (3.7) 8 (4, 10) 55
T1/2 (h) 7.9 (3.78) 6.7 (4.35, 15.9) 48 9.2 (4.29) 8.7 (3.35, 16.4) 47 8.8 (6.6) 8.8 (4.2, 13.5) 75
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Abbreviations: Cmin, minimum plasma concentrations; Cmax, maximum plasma concentration; Cavg, average plasma concentration; CV, coefficient of variation; max, maximum value; min, minimum value; SD, standard deviation; T1/2, half-life; Tmax, time to maximum plasma concentration.

3.3. Production of metabolites in capillary plasma throughout the dosing interval.

We evaluated the M1-Iva and M6-Iva metabolic activity by calculating the metabolite:parent ratio (MPR) over the dosing interval of 12 hours (Figure. 3). MPR significantly changed over time in capillary samples for M1-Iva (P=0.0012) and M6-Iva (P= 0.0417), as well as in venous samples for M1-Iva (P= 0.0078) or M6-Iva (P<0.0001). There was no difference in venous and capillary sampling of M1-Iva over time (P=0.923) or M6-Iva over time (P=1.04). The mean MPR of M1-Iva is 1.5 and M6-Iva is 1.6, which are lower than previously reported venous data. (19) The lower MPR reveals a lower total concentration of M1-Iva and M6-Iva compared to Iva in capillary plasma, which may be a result of differences in protein concentration, binding, and admixture with interstitial fluid.

Figure 3. Metabolite to parent ratio (MPR) for ivacaftor represents metabolic activity of the parent compound in vivo.

Figure 3.

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M1-Iva:Iva (A) and M6-Iva:Iva (B) ratios in capillary and venous plasma samples over 12 hours are shown. Venous data are derived from prior reported data (19), which is shown for comparison. Error bars represent standard error of the mean (SEM).

3.4. Iva and M1-Iva do not accumulate at high concentrations within the cellular lysate.

In our previous study, we did not see systematic evidence of in vivo intracellular accumulation (as had been reported previously (4)) of Iva at higher concentrations compared to venous plasma. (19) Capillary fluid has a number of differences (altered plasma protein concentration, pH, and fluid components) that we speculated might alter uptake of these compounds into the intracellular space. In Figure 4, we measured the concentrations of metabolites in capillary plasma compared to cells from the same individual. Figure 4 shows that the mean capillary:cellular ratio is 1.1 for Iva, supporting equal in vivo distribution between capillary fluid and cells. For M1-Iva, the mean capillary:cellular ratio is ≥2, which provides evidence that M1-Iva does not enter the cell as readily as Iva and is not likely to accumulate in the cellular space. Furthermore, although the capillary concentration of both compounds is higher at 6 hours, there is no significant change in the ratio between the two tissues. M6-Iva was found only in one cellular sample, and thus was excluded from this analysis.

Figure 4. Ratio between capillary plasma and cellular samples represents uptake from blood to intracellular space in vivo.

Figure 4.

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To assess the uptake of the compounds from the blood, we assessed capillary concentrations compared to cellular concentrations of Iva (A) and M1-Iva (B) at 0 hour and 6 hours after Iva administration. Bar indicates mean and error bars indicate SEM. Cellular concentration data derived from that reported previously for comparison. (19) ns, nonsignificant.

3.5. M6-Iva does not pass the plasma membrane in human airway epithelial cells.

We hypothesized that M1-Iva can cross the plasma membrane of cells from the interstitial fluid that surrounds cells and tissues in the body, whereas M6-Iva cannot. After ALI culture, 16HBE cells were treated with three doses (1, 100, and 1000nM) of M1-Iva or M6-Iva in the basolateral media for 48 hours prior to quantitation (Figure 5). A mean of 1000 ng/ml (2.5 μM) of M1-Iva was detected in the cells treated with 1000nM of M1-Iva, providing evidence that M1-Iva readily enters the airway epithelial cells. Surprisingly, only 15 ng/ml (0.04 μM) of M6-Iva was detected in the cells treated with 1000nM of M6-Iva. We expanded the treatment range of M6-Iva to test if higher applied concentrations could increase cellular concentrations of the compound. We treated 16HBE cells up to 5000nM of M6-Iva for 48 hours, which yielded an average of 81 ng/ml (0.19 μM) of M6-Iva in the cellular lysate (data not shown). Collectively, these data indicate that M6-Iva does not readily cross the plasma membrane of airway epithelial cells in the in vitro model.

Figure 5. Uptake of predominant metabolites into airway epithelia.

Figure 5.

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Human bronchial epithelial cells (16HBEs) were cultured at air-liquid interface (ALI) in transwells. Basolateral media was treated with M1-Iva (1, 100, and 1000nM) or M6-Iva (1000, 2000, and 5000nM) for 48 hours and concentrations were quantified via LC-MS/MS. Comparison of M1-Iva and M6-Iva intracellular concentrations after 16HBEs were treated with 1000nM of M1-Iva or M6-Iva are shown. **p=0.0084.

3.6. Neither M1-Iva nor M6-Iva are produced by human airway epithelial cells.

M1-Iva and M6-Iva are produced after Iva metabolism by CYP3A enzymes, which are predominantly expressed in the liver and enterocytes. (10) Multiple prior studies reported expression of CYP3A5 and CYP3A7 in extra-hepatic tissue, including in the lungs. (17, 18) Since these isoforms have overlapping substrate specificity with CYP3A4, we hypothesized that M1-Iva and M6-Iva could be produced by these enzymes within the epithelial cells. The HNEs (from CF patients and non-CF volunteers), HBEs (from CF patients), and the immortalized CFBE41o-cell line were treated with 1000nM of Iva on the basolateral side of ALI cultures for 48 hours, after which the cells were washed and lysed. Iva was detected in all the cell types at concentrations similar to those previously reported. (4, 41) However, LC-MS/MS showed no M1-Iva and M6-Iva (Figure 6). Furthermore, no M1-Iva and M6-Iva were detected in apical or basolateral media prior to cell lysis (data not shown). These data suggest metabolism of Iva by CYP3A isoforms in airway epithelial is not likely to significantly contribute to metabolite production in the cell. This data provides evidence that the detection of M1-Iva and M6-Iva in patients’ cellular samples comes from crossing the lipid bilayer from plasma and not from cellular metabolism.

Figure 6. Production of metabolites by human airway epithelial cells.

Figure 6.

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HNEs, HBEs, and CFBEs were used to detect production of metabolites. HNEs were collected from four individuals (both CF and non-CF), HBEs were obtained from three CF patients. ALI cultures were treated with 1000nM of Iva for 48 hours prior to quantification via LC-MS/MS. No M1-Iva and M6-Iva were detected in HNEs, HBEs, and CFBEs treated with Iva. LLOQ, lower limit of quantification.

4. Discussion

Overall, this study provides evidence that Iva and its metabolites are abundant in plasma, but only the parent compound and M1-Iva are taken up by the target epithelia, with low likelihood of further metabolism of Iva after reaching target epithelia. The differential entry of metabolites into airway epithelia was not previously known. M1-Iva is partially active as a potentiator, and may contribute to Iva effectiveness since it is able to enter epithelial cells. Because other studies reported that CYP3A isoform mRNA and protein were expressed in airway epithelia (16–18), we also completed preliminary studies to assess the presence of metabolites other than M1-Iva and M6-Iva. While quantitative detection of all possible metabolites is beyond the scope of the present study, our data showed no other metabolites in HNEs and small quantities of other metabolites in plasma, consistent with prior work. (42, 43) Cellular metabolism is unlikely to be a significant contributor to cellular clearance of these compounds.

Therapeutic drug monitoring (TDM) can be a useful tool to individualize dosing, but data on both ivacaftor and its metabolites is needed to understand overall impact on clinical responses. (20, 44) Iva can be converted to up to 11 metabolites, including M1-Iva and M6-Iva, which are predominant in human plasma. M6-Iva is an inactive metabolite, whereas M1-Iva is an active form, accounting for 1/6 of the activity of parent Iva. (9) Prior in vitro and in vivo studies suggested that Iva and its metabolites have off-target actions as well as interactions when they bind ligands and receptors. (20, 25, 45) Therefore, further investigation should determine if Iva and its metabolites compete for such binding sites on CFTR or other proteins. Previous publications suggest that Iva and M1-Iva could suppress the metabolic activity of CYP3A enzymes and that Iva may be present at high levels in epithelia. (21, 23) This effect may reduce drug metabolism in vivo, which could influence drug interactions and side effects. On the other hand, other studies have shown that M6-Iva may induce CYP enzyme activity, such as in the liver, which could also influence drug interactions. (23) Therefore, the study of metabolites is critical to understanding drug effectiveness and adverse effects of CF patients on modulator therapy.

Our study has several limitations. For drug-targeted cell studies, we tested Iva and its metabolite concentrations only in patients’ airway epithelial cells. Other tissues and cells commonly affected in CF patients may show different results, especially considering the risk of neuropsychological side effects that require crossing the blood-brain barrier and the risk of drug injury in the liver. (46, 47) Iva metabolites, or other compounds in combination therapy, may contribute to these side effects depending on metabolic activity and their entry into various tissues. These compounds should be investigated separately and in combination in future studies. Future studies should consider the evaluation of parent compounds and metabolites in a variety of tissue models to determine the etiology of these side effects. (20) Our study is limited to a small number of patients, and additional investigations with larger sample sizes should be considered.

In our study, we did not see any ivacaftor metabolites produced in airway epithelial cells, although individuals express CYP3A mRNA and protein in airway epithelia. (15, 18, 48) This finding should be further investigated. It is possible that despite evidence of expression, the CYP3A proteins are not able to metabolize these compounds in epithelia. The current literature regarding airway expression of P450 enzymes is inadequate to understand the role, if any, these enzymes might play in the clearance of airway-epithelial targeted drugs. Further investigation should be pursued on both the expression and activity of these CYP enzymes. However, our study also provides evidence that Iva and its metabolites may have differential entry into target tissues, which should be further studied in combination treatment and across tissue types to better develop novel therapeutic approaches for the use of these drugs.

Acknowledgement

We thank all the volunteers and their families who consented to donate the specimens that made this work possible. We thank the regulatory personnel in the Cystic Fibrosis Research Center and the Child Health Research Unit at UAB who were working on gaining regulatory approval and study coordination.

Funding

This work was supported by National Institutes of Health (NIH) Grant K23HL143167 (to J.S.G.), Cystic Fibrosis Foundation (CFF, GUIMBE18A0-Q and GUIMBE20A0-KB to J.S.G.). We also acknowledge support and contributions for this research from the UAB Cystic Fibrosis Center (NIH Grants R35HL135816 and DK072482 to S.M.R. and D.B.) and the CFF University of Alabama at Birmingham (UAB) Research and Development Program-Rowe19RO], and the UAB Center for Clinical and Translational Science (NIH Grant UL1TR001417). Funding sources provided no input to the content of the manuscript.

Abbreviations:

CF

cystic fibrosis

pwCF

people with CF

CFTR

cystic fibrosis transmembrane conductance regulator

Iva

Ivacaftor

M1-Iva

hydroxymethyl ivacaftor

M6-Iva

ivacaftor carboxylate

LC-MS/MS

liquid chromatography with tandem mass spectrometry

HNEs

human nasal epithelial cells

HBEs

human bronchial epithelial cells

ALI

air-liquid interface

CYP3A

Cytochrome P450 3A

Footnotes

Declaration of competing interest

Dr. Guimbellot reports consulting fees from Vertex Pharmaceuticals Incorporated, outside the submitted work. All other authors have no conflicts of interest to report.

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Data availability

The datasets in the current study are available from the corresponding author on reasonable request.

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The datasets in the current study are available from the corresponding author on reasonable request.

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