Crizotinib is a competitive small-molecule inhibitor of the anaplastic lymphoma kinase (ALK), c-Met/hepatocyte growth factor receptor, c-ros oncogene 1 (ROS1), and Recepteur d'Origine Nantais (RON) receptor tyrosine kinases.1-4 It is one of the first oncology drugs approved for a specific molecular-enriched patient population based on activity in that population.5 As a first-in-class multitargeted tyrosine kinase inhibitor, crizotinib was initially approved for the treatment of patients with ALK-positive metastatic non–small cell lung cancer5; approvals were subsequently achieved for patients with ROS1-positive metastatic non–small cell lung cancer and pediatric patients with relapsed or refractory, systemic anaplastic large cell lymphoma that is ALK positive. Crizotinib is also being investigated for the treatment of other tumor types harboring ALK mutations.

In humans, crizotinib is primarily metabolized by cytochrome P450 (CYP) 3A with minor contribution from other CYP enzymes including CYP2C19.6 A small amount of crizotinib is excreted in urine as the unchanged form.7 As well as being a substrate, crizotinib is also a moderate inhibitor of CYP3A.8 The mean apparent plasma terminal half-life of crizotinib 250 mg is 42 hours after a single dose,9 and steady state is reached after 15 days with repeated administration.8 The most abundant metabolite of crizotinib in plasma is its lactam metabolite, PF-06260182.7 Metabolism of PF-06260182 is believed to be more dependent on CYP3A than crizotinib.10 PF-06260182 is ≈2.5- to 7.7-fold less potent against ALK and 2.5- to 4-fold less potent against c-Met vs crizotinib.7 To explore the potential effect of liver dysfunction on the pharmacokinetics (PK) of crizotinib, a clinical study was performed in patients with advanced cancer.11 The results from this study suggested that the approved dose of 250 mg twice daily could be administered to patients with mild hepatic impairment, and reduced dose is necessary for patients with moderate hepatic impairment (200 mg twice daily) and severe hepatic impairment (250 mg once daily). A high-fat meal could result in a slight decrease in crizotinib exposure that was not considered clinically meaningful as the magnitude of change is within the variability of crizotinib PK.12, 13 Crizotinib demonstrates pH-dependent solubility in aqueous solution with decreased solubility at higher pH; solubility is >10 mg/mL at pH 1.6 and <0.1 mg/mL at pH 8.2.14 Therefore, the coadministration of agents that can affect gastric pH may potentially affect crizotinib absorption.

Proton pump inhibitors (PPIs) are a group of drugs that have strong inhibitory effects on acid secretion in the stomach through suppression of the gastric proton pump (H,K-ATPase) and thus increasing gastric pH. Esomeprazole is the S-isomer (the active isomer) of the first approved PPI, omeprazole, and is indicated for the treatment of symptomatic gastroesophageal reflux disease, including healing and maintenance of erosive esophagitis and as part of a triple-drug regimen for Helicobacter pylori infection. Esomeprazole can maintain intragastric pH at a higher level and >4 for a longer period than other PPIs.15, 16 It has been demonstrated that the maximal effect of omeprazole and esomeprazole are reached after daily dosing for 5 days.16

The potential effect of esomeprazole on crizotinib PK was evaluated in the current study in healthy adult participants. The primary objective of the study was to evaluate the potential effect of multiple doses of esomeprazole on the PK of crizotinib and its lactam metabolite (PF-06260182).7 The secondary objective of the current study was to assess the safety and tolerability of single crizotinib doses with or without esomeprazole in healthy adult participants.

Methods

The study protocol and informed consent documentation were reviewed and approved by the Ethics Committee of the Erasme Hospital (Brussels, Belgium) (NCT01549574). The study was conducted in compliance with the ethical principles originating in or derived from the Declaration of Helsinki and in compliance with all International Conference on Harmonization Good Clinical Practice Guidelines. In addition, all local regulatory requirements were followed, in particular, those affording greater protection to the safety of study participants.

Participants

Participants were healthy men or women of non–childbearing potential, aged 18 to 55 years, with a body mass index of 17.5 to 30.5 kg/m2 and a total body weight of >50 kg (110 lb). All participants signed an informed consent document before screening.

Exclusion criteria included evidence or history of clinically significant diseases, any condition possibly affecting drug absorption, a positive urine drug screen, history of excess alcohol consumption, treatment with an investigational drug within 30 days or 5 half-lives preceding the first dose of study medication, QTc >450 milliseconds at screening, use of drugs or dietary supplements within 7 days or 5 half-lives (whichever was longer) before the start of study-drug treatment, blood donation of approximately ≥500 mL within 56 days before dosing, and a positive serology for hepatitis B or C.

Study Design

This study was a phase 1, open-label, randomized, 2-period, 2-sequence, cross-over, single-dose study in healthy adult participants to evaluate the potential effect of multiple doses of the PPI esomeprazole on the PK of crizotinib and to assess the safety and tolerability of single crizotinib doses with or without esomeprazole. This study was conducted at the Pfizer Clinical Research Unit (PCRU) at the Erasme Hospital, Brussels, Belgium.

The treatment sequences are shown in Table 1. Participants were given 1 of 2 treatments in period 1. Treatment A (the reference) was a single oral 250-mg dose of crizotinib after overnight fasting. Treatment B (the test treatment) was esomeprazole 40 mg per day orally for 5 days and a single 250-mg dose of crizotinib after overnight fasting on day 5 of esomeprazole treatment. After a washout period of at least 14 days, in period 2, participants received the alternate treatment to that received in period 1. A randomization number was allocated to each participant and retained throughout the study, and corresponded to a treatment schedule determined by a Pfizer-generated randomization code.

Table 1. Treatment Sequences Sequence N Period 1 Washout Period Period 2 1 8 Treatment A (reference) At least 14 days Treatment B (test) 2 8 Treatment B (test) Treatment A (reference) Note: Treatment A (reference): single dose of crizotinib 250 mg after overnight fasting; Treatment B (test): esomeprazole 40 mg per day for 5 days and a single dose of crizotinib 250 mg after overnight fasting on day 5 of esomeprazole treatment.

Participants were allowed to withdraw from the study at any time for the following reasons: at their own request; or at the discretion of the investigator or sponsor because of safety, behavioral reasons, or the inability of the participant to comply with the protocol-required schedule of study visits or procedures. If the participant withdrew from the study and also withdrew consent for disclosure of future information, no further evaluations would have been performed and no additional data would have been collected. In treatment A, all participants were admitted to the PCRU on day 0, dosed with crizotinib 250 mg on day 1, discharged from the PCRU on day 5, and returned for an outpatient visit on day 7. In treatment B, all participants were admitted to the PCRU on day 0, dosed with esomeprazole 40 mg and discharged on day 1, continued esomeprazole 40 mg every day at home from day 2 to day 4, readmitted to PCRU and dosed with esomeprazole 40 mg and crizotinib 250 mg on day 5, discharged again on day 9, and returned for an outpatient visit on day 11. If necessary, a follow-up visit would be performed after the last period.

Crizotinib doses were given with 240 mL of ambient-temperature water and swallowed whole without chewing in the morning after overnight fasting. Esomeprazole doses were administered according to the label when given alone and under the same conditions as crizotinib when given with crizotinib. Crizotinib was supplied by Pfizer Inc as a commercial capsule, and esomeprazole was supplied at PCRU as a Nexium® 40-mg tablet. All study treatments at PCRU were administered under supervision. In order to standardize the conditions of PK sampling, restrictions were placed on eating, drinking, smoking, and physical activity before and/or during the study as previously described.13

Pharmacokinetic Sample Collection and Analytic Methods

Blood samples (3 mL) were collected into appropriately labeled tubes containing dipotassium ethylenediaminetetraacetic acid at time 0 (predose) and 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 48, 72, 96, and 144 hours after crizotinib dosing. Once collected, blood samples were processed immediately, and plasma concentrations of crizotinib and its metabolite, PF-06260182, were determined as previously described.13

Calibration standard responses were linear over the range of 0.200 to 200 ng/mL for crizotinib and PF-06260182.13 Those samples with concentrations greater than the upper limit of quantification were diluted into calibration range. Concentrations below the lower limit of quantification (LLOQ, 0.200 ng/mL) were reported as below LLOQ.

The between-day assay accuracy, expressed as percent relative error, for quality-control (QC) concentrations ranged from –2.0% to –1.0% for crizotinib, and from 0.0% to 2.7% for PF-06260182 for the low (0.600 ng/mL), medium (70.0 ng/mL), high (150 ng/mL), and diluted (150 ng/mL) QC samples. Assay precision, expressed as the between-day percent coefficient of variation of the mean estimated concentrations of QC samples, was ≤4.3% for crizotinib and ≤4.6% for PF-06260182 for the low, medium, high, and diluted concentrations.

Pharmacokinetic Analysis

Plasma concentration–time data for crizotinib and PF-06260182 were analyzed to determine PK parameters using noncompartmental methods via electronic noncompartmental analysis (v2.2.3, Pfizer internal program, Groton, Connecticut).13 The definition and method of determination for each PK parameter are listed in Table 2. Samples below the LLOQ were set to 0.00 ng/mL and actual sample collection times were used for analysis. Area under the plasma concentration–time profile (AUC) from time 0 extrapolated to infinity (AUCinf) and plasma terminal elimination half-life (t1/2) were reported where the following criteria were met: a well-characterized terminal phase defined as one with at least 3 data points, an r2 ≥0.9 (goodness-of-fit statistics for the log-linear regression), and ≤20% extrapolation for AUCinf.

Table 2. Pharmacokinetic Parameter Determination Parameter Definition Method of Determination AUClast Area under the plasma concentration–time profile from time 0 to the time of the last quantifiable concentration (Clast) Linear-log trapezoidal method AUCinf Area under the plasma concentration–time profile from time 0 extrapolated to infinity AUClast + (Clast/kel), where Clast was the predicted plasma concentration at the last quantifiable time point estimated from the log-linear regression analysis Cmax Maximum plasma concentration Observed directly from data tmax Time to Cmax Observed directly from data as time of first occurrence t1/2 Terminal elimination half-life Loge(2)/kel, where kel is the terminal phase rate constant calculated by a linear regression of the log-linear concentration–time curve; only those data points judged to describe the terminal log-linear decline were used in the regression CL/F Apparent clearance after oral dose Dose/AUCinf after oral dose MRCmax Metabolite to parent ratio of Cmax (Cmax/464.33)a/(AUClast/450.34)b MRAUClast Metabolite to parent ratio of AUClast (AUClast/464.33)a/(AUClast/450.34)b MRAUCinf Metabolite to parent ratio of AUCinf (AUCinf/464.33)a/(AUCinf/450.34)b Pharmacokinetic parameter values were calculated using electronic noncompartmental analysis version 2.2.3. aMetabolite (PF-06260182) data corrected for molecular weights (converted from ng to nmol). bCrizotinib data corrected for molecular weights (converted from ng to nmol). Statistical Analysis

Sample-size calculation was based on estimates of within-subject deviations of 0.172 for loge AUCinf and 0.186 for loge maximum plasma concentration (Cmax) obtained from a previous PK study in healthy participants.

A sample size of 14 participants provided 90% confidence intervals (CIs) for the difference between treatments of ±0.1226 and ±0.1326 on the natural log scale for AUCinf and Cmax, respectively, with 90% coverage probability.

All treated participants with at least 1 crizotinib and one PF-06260182 concentration measurement were included in PK analysis. PK parameters were summarized descriptively by treatment and analyte. Natural log-transformed exposure parameters (AUC and Cmax) of crizotinib were analyzed as previously described.13 The statistical analyses were performed using SAS version 9.4 (SAS Institute, Cary, North Carolina).

Adverse Events

All participants who received at least 1 dose of the study medication were included in the safety analyses.

Adverse events (AEs), electrocardiograms (ECGs), blood pressure, pulse rate, and safety laboratory data were reviewed on an ongoing basis during the study to evaluate the safety of participants. Any clinical laboratory, ECG, blood pressure, and pulse rate abnormalities of potential clinical concern were described. Safety data were summarized descriptively.

Results

A total of 16 male participants were enrolled and participated in the study between May 3 and May 29, 2012. One participant who was randomly assigned to sequence 1 (Table 1) was discontinued during period 1 due to the participant's decision to withdraw from the study for personal reasons. Another participant who was randomly assigned to sequence 2 discontinued before period 2 due to safety reasons (hematuria, which was considered moderate in severity and related to the study drug; the event resolved spontaneously ≈25 days later). A summary of demographic and baseline characteristics is shown in Table 3.

Table 3. Participant Demographics and Baseline Characteristics Participants (N = 16) Male, % 100 Age category, y, n <18 0 18-25 0 26-35 5 36-45 7 >45 4 Mean age, y (range) [SD] 39.3 (26-53) [7.6] Race, n White 14 Other 2 Mean weight, kg (range) [SD] 80.5 (61.8-102.8) [10.7] Mean body mass index,a kg/m2 (range) [SD] 24.9 (19.5-28.5) [2.4] Mean height, cm (range) [SD] 179.8 (163-190) [6.5] SD, standard deviation. aBody mass index was defined as weight/(height × 0.01)2.

In each treatment group, 15 participants were included in the PK analysis. Mean plasma concentration–time profiles of crizotinib and its metabolite PF-06260182 after each treatment are presented in Figure 1.

Mean (SD) plasma concentration–time curve of crizotinib (A) and PF-06260182 (B) on a semilogarithmic scale (the insets depict the same data on a linear scale). SD, standard deviation.

Crizotinib

Coadministration with esomeprazole (40 mg once daily × 5 days) decreased crizotinib total exposure (AUCinf) by ≈10% and had no effect on peak exposure (Cmax) (Figures 2A and 2B). Median time to Cmax values were 5 hours with or without esomeprazole (Table 4). No change in apparent t1/2 was observed, with geometric mean values of 33.2 and 35.8 hours seen for crizotinib alone or with esomeprazole, respectively. Apparent oral clearance was similar for both treatments, with geometric mean values of 102.5 and 117.8 L/h for crizotinib alone or with esomeprazole, respectively.

Individual and mean AUCinf and Cmax values by treatment. (A) Crizotinib AUCinf; (B) crizotinib Cmax; (C) PF-06260182 AUCinf; (D) PF-06260182 Cmax. Circles represent the individual values and stars represent geometric means. Box plots provide median and 25%/75% quartiles with whiskers to the last point within 1.5 times the interquartile range. Arithmetic means (diamonds) and standard deviations are shown to the right of the box plots. AUCinf, area under the plasma concentration–time profile from time 0 extrapolated to infinity; Cmax, maximum plasma concentration.

Table 4. Summary of Plasma Crizotinib and PF-06260182 Pharmacokinetic Parameter Values Following Single Oral Crizotinib Doses Alone and After 5 Days of Daily Esomeprazole 40 mg Dosing Parameter Summary Statisticsa by Treatment Crizotinib 250 mg (n = 15) Esomeprazole 40 mg + Crizotinib 250 mg (n = 15) Parameterb (Units) Geometric Mean (%CV) Arithmetic Mean ± SD Geometric Mean (%CV) Arithmetic Mean ± SD Crizotinib AUCinf, ng • h/mL 2438 (42) 2623 ± 1091 2122 (39) 2265 ± 891 AUClast, ng • h/mL 2307 (43) 2490 ± 1072 2022 (40) 2166 ± 876 CL/F, L/h 102.5 (38) 109.9 ± 42.2 117.8 (33) 124.8 ± 40.9 Cmax, ng/mL 118.5 (31) 124.5 ± 39.2 114.8 (28) 119.0 ± 32.9 tmax, h 5.00 (2.00-6.00) 5.00 (3.00-6.00) t1/2, h 33.2 ± 7.0 35.8 ± 4.4 PF-06260182c AUCinf, ng • h/mL 451 (47) 492 ± 232 364 (33) 383 ± 127 AUClast, ng • h/mL 451 (46) 490 ± 225 357 (34) 376 ± 126 Cmax, ng/mL 35.9 (34) 37.9 ± 13.0 26.8 (25) 27.7 ± 6.8 tmax, h 5.02 (5.00-8.00) 6.00 (5.00-8.05) t1/2, h 19.7 ± 7.1 19.5 ± 5.9 MRAUClast 0.19 (18) 0.17 (13) MRAUCinf 0.18 (16) 0.17 (12) MRCmax 0.29 (26) 0.23 (17) AUCinf, area under the plasma concentration–time profile from time 0 extrapolated to infinity; AUClast, area under the plasma concentration–time profile from time 0 to the time of the last quantifiable concentration; CL/F, apparent clearance after oral dose; Cmax, maximum plasma concentration; CV, coefficient of variation; MRAUCinf, metabolite to parent ratio of AUCinf; MRAUClast, metabolite to parent ratio of AUClast; MRCmax, metabolite to parent ratio of Cmax; SD, standard deviation; t1/2, terminal elimination half-life; tmax, time to Cmax. aGeometric mean (%CV) and arithmetic mean ± SD for all except: median (range) for tmax and arithmetic mean ± SD only for t1/2. bPharmacokinetic parameters are defined in Table 2. cn = 14 for AUCinf, t1/2, and MRAUCinf of PF-06260182 in the crizotinib 250-mg group.

The ratios of adjusted geometric means (90%CI) of crizotinib AUCinf and Cmax were 89.81% (79.05-102.03) and 101.84% (91.51-113.33), respectively, following administration of crizotinib 250 mg + esomeprazole (40 mg once daily × 5 days) relative to crizotinib 250 mg (Table 5). The corresponding 90%CI for the adjusted geometric means for AUCinf fell marginally outside of the lower (80%) limit for bioequivalence, whereas the corresponding 90%CIs for the adjusted geometric mean for the Cmax ratios were contained within the 80% to 125% bioequivalence range.

Table 5. Statistical Summary of Treatment Comparisons for Crizotinib and PF-06260182 With or Without PPI Adjusted Geometric Means Parametera (Units) Testb Referenceb Ratio (%) (Test/Reference) 90%CI (%) Crizotinib AUCinf, ng • h/mL 2125 2366 89.81 79.05-102.03 AUClast, ng • h/mL 2014 2238 89.99 78.84-102.71 Cmax, ng/mL 116.8 114.7 101.84 91.51-113.33 PF-06260182 AUCinf, ng • h/mL 367.8 446.0 82.46 71.13-95.60 AUClast, ng • h/mL 359.8 436.9 82.34 71.08-95.39 Cmax, ng/mL 26.9 34.8 77.38 69.12-86.62 AUCinf, area under the plasma concentration–time profile from time 0 extrapolated to infinity; AUClast, area under the plasma concentration–time profile from time 0 to the time of the last quantifiable concentration; Cmax, maximum plasma concentration; PPI, proton pump inhibitor. aPharmacokinetic parameters are defined in Table 2. bTest: esomeprazole 40 mg per day for 5 days and single 250-mg crizotinib dose after overnight fasting on day 5 of esomeprazole treatment; reference: single 250-mg crizotinib dose after overnight fasting. PF-06260182

Esomeprazole treatment (40 mg once daily for 5 days) resulted in moderate decreases of approximately 18% and 23% in PF-06260182 AUCinf and Cmax, respectively (Figures 2C and 2D). Median time to Cmax values were similar with or without esomeprazole, with a range of 5 to 6 hours (Table 4). No change in apparent t1/2 was observed, with a mean value of ≈20 hours for both treatments.

The ratios of adjusted geometric means (90%CI) of PF-06260182 AUCinf and Cmax were 82.46% (71.13-95.60) and 77.38% (69.12-86.62), respectively, following administration of crizotinib 250 mg + esomeprazole (40 mg once daily × 5 days) relative to crizotinib 250 mg (Table 5). This change in exposure is still within the PK variability of ≈30% to 40%.

Modest decreases in metabolite (PF-06260182) to parent (crizotinib) ratios for measures of systemic exposure (Cmax and AUC) were observed following administration of crizotinib with esomeprazole compared with crizotinib alone (Table 4).

Safety and Tolerability

A summary of the incidence of treatment-emergent and treatment-related AEs is provided in Table 6. The most frequently reported AE in this study was diarrhea, which was mild in severity, treatment related, and experienced by 11 participants during treatment with crizotinib 250 mg and by 7 participants during the combined treatment of multiple doses of esomeprazole followed by a single dose of crizotinib. The only other AE that occurred in >2 participants during any treatment phase was abdominal pain, which was experienced by 3 participants during treatment with crizotinib 250 mg and was considered treatment related. By system organ class, gastrointestinal disorders (crizotinib 250 mg, 11 participants; esomeprazole 40 mg, 3 participants; esomeprazole 40 mg + crizotinib 250 mg, 10 participants) and nervous system disorders (crizotinib 250 mg, 4 participants; esomeprazole 40 mg, 2 participants; esomeprazole 40 mg + crizotinib 250 mg, 1 participant) were the most common disorders.

Table 6. Summary of Treatment-Emergent Adverse Events Number of All Causality AEs (Number of Treatment-Related AEs) Crizotinib 250 mg (N = 15) Esomeprazole 40 mg + Crizotinib 250 mg (N = 15) Participants evaluable for AEs 15 15 Number of AEs 28 (24) 23 (17) Participants with AEs 12 (12) 13 (10) Participants with serious AEs 0 0 Participants with severe AEs 0 0 Discontinuations due to AEs 0 1 (1) Dose reductions or temporary discontinuation due to AEs 0 0 AEs in >1 participant in either group, by MedDRA preferred term Diarrhea 11 (11) 7 (7) Abdominal pain 3 (3) 0 Abdominal pain upper 0 2 (2) Abnormal gastrointestinal sounds 1 (1) 2 (2) Fatigue 2 (2) 1 (1) Nausea 2 (2) 1 (1) Dizziness 2 (2) 0 Headache 2 (2) 0