CLINICAL PHARMACOLOGY
Mechanism Of Action
Osimertinib is a kinase inhibitor of the epidermal growth
factor receptor (EGFR), which binds irreversibly to certain mutant forms of
EGFR (T790M, L858R, and exon 19 deletion) at approximately 9- fold lower
concentrations than wild-type. Two pharmacologically-active metabolites (AZ7550
and AZ5104 circulating at approximately 10% of the parent) with similar
inhibitory profiles to osimertinib have been identified in the plasma after
oral administration of osimertinib. AZ7550 showed a similar potency to
osimertinib, while AZ5104 showed greater potency against exon 19 deletion and
T790M mutants (approximately 8-fold) and wild-type (approximately 15-fold)
EGFR. In vitro, osimertinib also inhibited the activity of HER2, HER3, HER4,
ACK1, and BLK at clinically relevant concentrations.
In cultured cells and animal tumor implantation models,
osimertinib exhibited anti-tumor activity against NSCLC lines harboring
EGFR-mutations (T790M/L858R, L858R, T790M/exon 19 deletion, and exon 19 deletion)
and, to a lesser extent, wild-type EGFR amplifications. Osimertinib distributed
to the brain in multiple animal species (monkey, rat, and mouse) with brain to
plasma AUC ratios of approximately 2 following oral dosing. These data are
consistent with observations of tumor regression and increased survival in
osimertinib- versus control-treated animals in a pre-clinical mutant-EGFR
intracranial mouse metastasis xenograft model (PC9; exon 19 deletion).
Pharmacodynamics
Based on an analysis of dose-exposure response
relationships over the dose range of 20 mg (0.25 times the recommended dose) to
240 mg (3 times the recommended dose), no apparent relationship between osimertinib
exposure and overall response rate, duration of response and progression-free
survival was identified; however, there were limited data available at the 20
mg dose. Over the same dose range, increased exposure led to increased
probability of adverse reactions, specifically rash, diarrhea and ILD.
Cardiac Electrophysiology
The QTc interval prolongation potential of osimertinib
was assessed in 210 patients who received TAGRISSO 80 mg daily in AURA2. A
central tendency analysis of the QTcF data at steady-state demonstrated that
the maximum mean change from baseline was 16.2 msec (upper bound of two-sided 90%
confidence interval (CI) 17.6 msec). A pharmacokinetic/pharmacodynamic analysis
in AURA2 suggested a concentration-dependent QTc interval prolongation of 14
msec (upper bound of two-sided 90% CI: 16 msec) at a dose of TAGRISSO 80 mg.
Pharmacokinetics
The area under the plasma concentration-time curve (AUC)
and maximal plasma concentration (Cmax) of osimertinib increased dose
proportionally over 20 to 240 mg dose range (i.e., 0.25 to 3 times the recommended
dosage) after oral administration and exhibited linear pharmacokinetics (PK). Administration
of TAGRISSO orally once daily resulted in approximately 3-fold accumulation
with steady-state exposures achieved after 15 days of dosing. At steady state,
the Cmax to Cmin (minimal concentration) ratio was 1.6-fold.
Absorption
The median time to Cmax of osimertinib was 6 hours (range
3-24 hours).
Following administration of a 20 mg TAGRISSO tablet with
a high-fat, high-calorie meal (containing approximately 58 grams of fat and
1000 calories), the Cmax and AUC of osimertinib were comparable to that under
fasting conditions.
Distribution
The mean volume of distribution at steady-state (Vss/F)
of osimertinib was 918 L. Plasma protein binding of osimertinib was 95%.
Elimination
Osimertinib plasma concentrations decreased with time and
a population estimated mean half-life of osimertinib was 48 hours, and oral
clearance (CL/F) was 14.3 (L/h).
Metabolism
The main metabolic pathways of osimertinib were oxidation
(predominantly CYP3A) and dealkylation in vitro. Two pharmacologically active
metabolites (AZ7550 and AZ5104) have been identified in the plasma after
TAGRISSO oral administration. The geometric mean exposure (AUC) of each
metabolite (AZ5104 and AZ7550) was approximately 10% of the exposure of
osimertinib at steady-state.
Excretion
Osimertinib is primarily eliminated in the feces (68%)
and to a lesser extent in the urine (14%). Unchanged osimertinib accounted for
approximately 2% of the elimination.
Specific Populations
No clinically significant differences in the
pharmacokinetics of osimertinib were observed based on age, sex, ethnicity,
body weight, baseline albumin, line of therapy, smoking status, renal function
(creatinine clearance (CLcr) ≥15 mL/min by Cockcroft-Gault), or hepatic
impairment (Child-Pugh A and B, or total bilirubin ≤ ULN and AST > ULN
or total bilirubin between 1 to 3 times ULN and any AST). The pharmacokinetics
of osimertinib in patients with end-stage renal disease (CLcr < 15 mL/min)
or severe hepatic impairment (total bilirubin 3 to 10 times ULN and any AST)
are unknown [see Use In Specific Populations].
Drug Interaction Studies
Effect Of Other Drugs On TAGRISSO In Clinical
Pharmacokinetic Studies
Strong CYP3A Inducers
The steady-state AUC of osimertinib was reduced by 78% in
patients when coadministered with rifampin (600 mg daily for 21 days) [see DRUG
INTERACTIONS].
Strong CYP3A Inhibitors
Co-administering TAGRISSO with 200 mg itraconazole twice
daily (a strong CYP3A4 inhibitor) had no clinically significant effect on the
exposure of osimertinib (AUC increased by 24% and Cmax decreased by 20%).
Gastric Acid Reducing Agents
The exposure of osimertinib was not affected by
concurrent administration of a single 80 mg TAGRISSO tablet following 40 mg
omeprazole administration for 5 days.
Effect Of Osimertinib On Other Drugs In Clinical
Pharmacokinetic Studies
BCRP Substrates
Co-administering TAGRISSO with rosuvastatin (a BCRP
substrate) increased rosuvastatin AUC by 35% and Cmax by 72% [see DRUG
INTERACTIONS].
P-gp Substrates
Co-administering TAGRISSO with fexofenadine (a P-gp
substrate) increased fexofenadine AUC and Cmax by 56% and 76% after a single
dose and 27% and 25% at steady state, respectively.
CYP3A4 Substrates
Co-administering TAGRISSO with simvastatin (a CYP3A4
substrate) had no clinically significant effect on the exposure of simvastatin.
In Vitro Studies
CYP450 Metabolic Pathways
Osimertinib does not inhibit CYP1A2, 2A6, 2B6, 2C8, 2C9,
2C19, 2D6 and 2E1. Osimertinib induced CYP1A2 enzymes.
Transporter Systems
Osimertinib is a substrate of P-glycoprotein and BCRP and
is not a substrate of OATP1B1 and OATP1B3. Osimertinib is an inhibitor of BCRP
and does not inhibit OAT1, OAT3, OATP1B1, OATP1B3, MATE1, MATE2K and OCT2.
Clinical Studies
Previously Untreated EGFR Mutation-Positive Metastatic
Non-Small Cell Lung Cancer
The efficacy of TAGRISSO was demonstrated in a
randomized, multicenter, double-blind, activecontrolled trial (FLAURA
[NCT02296125]) in patients with EGFR exon 19 deletion or exon 21 L858R mutation-positive,
metastatic NSCLC, who had not received previous systemic treatment for
metastatic disease. Patients were required to have measurable disease per
RECIST v1.1, a WHO performance status of 0-1, and EGFR exon 19 deletion or exon
21 L858R mutation in tumor prospectively identified by the cobas® EGFR Mutation
Test in a central laboratory or by an investigational assay at a CLIA-certified
or accredited laboratory. Patients with CNS metastases not requiring steroids
and with stable neurologic status for at least two weeks after completion of
definitive surgery or radiotherapy were eligible. Patients were assessed at the
investigator's discretion for CNS metastases if they had a history of, or
suspected, CNS metastases at study entry.
Patients were randomized (1:1) to receive TAGRISSO 80 mg
orally once daily or to receive gefitinib 250 mg orally once daily or erlotinib
150 mg orally once daily until disease progression or unacceptable toxicity.
Randomization was stratified by EGFR mutation type (exon 19 deletion or exon 21
L858R mutation) and ethnicity (Asian or non-Asian). Patients randomized to the
control arm were offered TAGRISSO at the time of disease progression if tumor
samples tested positive for the EGFR T790M mutation. The major efficacy outcome
measure was progression-free survival (PFS), as assessed by investigator.
Additional efficacy outcome measures included overall survival (OS) and overall
response rate (ORR).
A total of 556 patients were randomized to TAGRISSO
(n=279) or to control (gefitinib n=183; erlotinib n=94). The median age was 64
years (range 26-93 years); 54% were < 65 years of age; 63% were female; 62%
were Asian and 64% were never smokers. Baseline WHO performance status was 0
(41%) or 1 (59%); 5% had Stage IIIb and 95% had Stage IV; and 7% received prior
systemic cytotoxic chemotherapy as neoadjuvant or adjuvant therapy. With regard
to EGFR tumor testing, 63% were exon 19 deletion and 37% were exon 21 L858R; 5
patients (<1%) also had a concomitant de novo T790M mutation. EGFR mutation
status was confirmed centrally using the cobas EGFR Mutation Test in 90% of
patients. Of those randomized to investigator's choice of erlotinib or
gefitinib, 55 patients (20%) received TAGRISSO as the next line of
antineoplastic therapy.
FLAURA demonstrated a statistically significant
improvement in PFS for patients randomized to TAGRISSO as compared to erlotinib
or gefitinib (see Table 6 and Figure 1). Overall survival data were not mature
at the time of the final PFS analysis.
Table 6: Efficacy Results in FLAURA according to
Investigator Assessment
Efficacy Parameter |
TAGRISSO
(N=279) |
EGFR TKI (gefitinib or erlotinib)
(N=277) |
Progression-Free Survival (PFS) |
PFS events (%) |
136 (49) |
206 (74) |
Progressive disease (%) |
125 (45) |
192 (69) |
Deatha (%) |
11(4) |
14(5) |
Median PFS in months (95% CI) |
18.9(15.2, 21.4) |
10.2 (9.6, 11.1) |
Hazard Ratio (95% CI)b, c |
0.46 (0.37, 0.57) |
p-valueb,d |
P< 0.0001 |
Overall Response Rate (ORR)e |
ORR, % (95% CI)b |
77 (71, 82) |
69 (63, 74) |
Complete response, % |
2% |
1% |
Partial response, % |
75% |
68% |
Duration of Response (DoR)e |
Median in months (95% CI) |
17.6(13.8, 22.0) |
9.6 (8.3, 11.1) |
a Without documented radiological disease
progression
b Stratified by ethnicity (Asian vs. non-Asian) and mutation status
(Ex19del vs. L858R)
c Pike estimator
d Stratified log-rank test
e Confirmed responses |
Figure 1: Kaplan-Meier Curves of PFS by Investigator
Assessment in FLAURA
In a supportive analysis of PFS according to blinded
independent central review, median PFS was 17.7 months in the TAGRISSO arm
compared to 9.7 months in the EGFR TKI comparator arm (HR=0.45; 95% CI: 0.36,
0.57).
Of 556 patients, 200 patients (36%) had baseline brain
scans reviewed by BICR; this included 106 patients in the TAGRISSO arm and 94
patients in the investigator choice of EGFR TKI arm. Of these 200 patients, 41
had measurable CNS lesions per RECIST v1.1. Results of pre-specified
exploratory analyses of CNS ORR and DoR by BICR in the subset of patients with
measurable CNS lesions at baseline are summarized in Table 7.
Table 7:CNS ORR and DOR by BICR in Patients with
Measurable CNS Lesions at Baseline in FLAURA
|
TAGRISSO
N=22 |
EGFR TKI (gefitinib or erlotinib)
N=19 |
CNS Tumor Response Assessmenta,b |
CNS ORR, % (95% CI) |
77% (55, 92) |
63% (38, 84) |
Complete response |
18% |
0% |
Duration of CNS Responsec |
Number of responders |
17 |
12 |
Response Duration ≥6 months |
88% |
50% |
Response Duration ≥12 months |
47% |
33% |
a According to RECIST v1.1.
b Based on confirmed response.
c Based on patients with response only; DoR defined as the time from
the date of first documented response (complete response or partial response)
until progression or death event. |
Previously Treated EGFR T790M Mutation-Positive
Metastatic Non-Small Cell Lung Cancer
The efficacy of TAGRISSO was demonstrated in a
randomized, multicenter open-label, active-controlled trial in patients with
metastatic EGFR T790M mutation-positive NSCLC who had progressed on prior systemic
therapy, including an EGFR TKI (AURA3). All patients were required to have EGFR
T790M mutation-positive NSCLC identified by the cobas® EGFR Mutation Test
performed in a central laboratory prior to randomization.
A total of 419 patients were randomized 2:1 to receive
TAGRISSO (n=279) or platinum-based doublet chemotherapy (n=140). Randomization
was stratified by ethnicity (Asian vs. non-Asian). Patients in the TAGRISSO arm
received TAGRISSO 80 mg orally once daily until intolerance to therapy, disease
progression, or investigator determination that the patient was no longer
benefiting from treatment. Patients in the chemotherapy arm received pemetrexed
500 mg/m² with carboplatin AUC5 or pemetrexed 500mg/m² with cisplatin 75 mg/m²
on Day 1 of every 21-day cycle for up to 6 cycles. Patients whose disease had
not progressed after four cycles of platinum-based chemotherapy could have
received pemetrexed maintenance therapy (pemetrexed 500 mg/m² on Day 1 of every
21-day cycle).
The major efficacy outcome measure was progression-free
survival (PFS) according to Response Evaluation Criteria in Solid Tumors
(RECIST v1.1) by investigator assessment. Additional efficacy outcome measures
included overall response rate (ORR), duration of response (DoR), and overall
survival (OS). Patients randomized to the chemotherapy arm who had radiological
progression according to both investigator and blinded independent central
review (BICR) were permitted to cross over to receive treatment with TAGRISSO.
The baseline demographic and disease characteristics of
the overall trial population were: median age 62 years (range: 20-90 years), ≥75
years old (15%), female (64%), White (32%), Asian (65%), never smoker (68%),
WHO performance status 0 or 1 (100%). Fifty-four percent (54%) of patients had
extra-thoracic visceral metastases, including 34% with central nervous system
(CNS) metastases (including 11% with measurable CNS metastases) and 23% with
liver metastases. Forty-two percent (42%) of patients had metastatic bone
disease.
In AURA3, there was a statistically significant
improvement in PFS in the patients randomized to TAGRISSO compared to
chemotherapy (See Table 8 and Figure 2). Overall survival data were not mature
at the time of the PFS analysis.
Table 8: Efficacy Results According to Investigator
Assessment in AURA3
Efficacy Parameter |
TAGRISSO
(N=279) |
Chemotherapy
(N=140) |
Progression-Free Survival |
Number of events (%) |
140 (50) |
110 (79) |
Progressive disease |
129 (46) |
104 (74) |
Deatha |
11 (4) |
6 (4) |
Median PFS in months (95% CI) |
10.1 (8.3, 12.3) |
4.4 (4.2, 5.6) |
Hazard Ratio (95% CI)b,c |
0.30 (0.23,0.41) |
P-valueb,d |
<0.001 |
Overall Response Ratee |
Overall Response Rate |
65% |
29% |
(95% CI) |
(59%, 70%) |
(21%, 37%) |
Complete response |
1% |
1% |
Partial response |
63% |
27% |
P-valueb,f |
<0.001 |
Duration of Response (DoR) |
Median Duration of Response in months (95% CI) |
11.0 (8.6, 12.6) |
4.2 (3.0, 5.9) |
a Without documented radiological disease
progression
b Stratified by ethnicity (Asian vs. non-Asian)
c Pike estimator
d Stratified log-rank test
e Confirmed
f Logistic regression analysis |
Figure 2: Kaplan-Meier Curves of PFS by Investigator
Assessment in AURA3
In a supportive analysis of PFS according to blinded independent
central review, median PFS was 11 months in the TAGRISSO arm compared to 4.2
months in the chemotherapy arm (HR 0.28; 95% CI: 0.20, 0.38).
Of 419 patients, 205 (49%) had baseline brain scans
reviewed by BICR; this included 134 (48%) patients in the TAGRISSO arm and 71
(51%) patients in the chemotherapy arm. Assessment of CNS efficacy by RECIST
v1.1 was performed in the subgroup of 46/419 (11%) patients identified by BICR
to have measurable CNS lesions on a baseline brain scan. Results are summarized
in Table 9.
Table 9: CNS ORR and DoR by BICR in Patients with
Measurable CNS Lesions at Baseline in AURA3
|
TAGRISSO
N=30 |
Chemotherapy
N=16 |
CNS Tumor Response Assessmenta,b |
CNS ORR, % (95% CI) |
57% (37, 75) |
25% (7, 52) |
Complete response |
7% |
0 |
Duration of CNS Responseb,c |
Number of responders |
17 |
4 |
Response Duration ≥ 6 months |
47% |
0 |
Response Duration ≥ 9 months |
12% |
0 |
a According to RECIST v1.1.
b Based on confirmed response.
c Based on patients with response only; DoR defined as the time from
the date of first documented response (complete response or partial response)
until progression or death event. |