CLINICAL PHARMACOLOGY
Mechanism Of Action
Epidermal growth factor
receptor (EGFR) is expressed on the cell surface of both normal and cancer
cells. In some tumor cells signaling through this receptor plays a role in
tumor cell survival and proliferation irrespective of EGFR mutation status.
Erlotinib reversibly inhibits the kinase activity of EGFR, preventing
autophosphorylation of tyrosine residues associated with the receptor and
thereby inhibiting further downstream signaling. Erlotinib binding affinity for
EGFR exon 19 deletion or exon 21 (L858R) mutations is higher than its affinity
for the wild type receptor. Erlotinib inhibition of other tyrosine kinase receptors
has not been fully characterized.
Pharmacokinetics
Absorption
Erlotinib is about 60% absorbed
after oral administration. Peak plasma levels occur 4 hours after dosing.
Effect of Food
Food increased the
bioavailability of erlotinib to approximately 100%.
Distribution
Erlotinib is 93% protein bound
to plasma albumin and alpha-1 acid glycoprotein (AAG).
Erlotinib has an apparent
volume of distribution of 232 liters.
Elimination
Erlotinib is eliminated with a median half-life of 36.2
hours in patients receiving the single-agent TARCEVA 2nd/3rd line regimen. Time
to reach steady state plasma concentration would therefore be 7-8 days.
Metabolism
Erlotinib is metabolized
primarily by CYP3A4 and to a lesser extent by CYP1A2, and the extrahepatic
isoform CYP1A1, in vitro.
Excretion
Following a 100 mg oral dose, 91% of the dose was
recovered: 83% in feces (1% of the dose as intact parent) and 8% in urine (0.3%
of the dose as intact parent).
Specific Populations
Neither age, body weight, nor gender had a clinically
significant effect on the systemic exposure of erlotinib in NSCLC patients
receiving single-agent TARCEVA for 2nd/3rd line treatment or for maintenance
treatment, and in pancreatic cancer patients who received erlotinib plus
gemcitabine. The pharmacokinetics of TARCEVA in patients with compromised renal
function is unknown.
Patients with Hepatic Impairment
In vitro and in vivo evidence suggest that erlotinib is
cleared primarily by the liver. However, erlotinib exposure was similar in
patients with moderately impaired hepatic function (Child-Pugh B) compared with
patients with adequate hepatic function including patients with primary liver
cancer or hepatic metastases.
Patients That Smoke Tobacco Cigarettes
In a single-dose pharmacokinetics trial in healthy
volunteers, cigarette smoking (moderate CYP1A2 inducer) increased erlotinib
clearance and decreased erlotinib AUC0-inf by 64% (95% CI, 46-76%) in current
smokers compared with former/never smokers. In a NSCLC trial, current smokers
achieved erlotinib steady-state trough plasma concentrations which were
approximately 2-fold less than the former smokers or patients who had never
smoked. This effect was accompanied by a 24% increase in apparent erlotinib
plasma clearance. In another study which was conducted in NSCLC patients who
were current smokers, pharmacokinetic analyses at steady-state indicated a
dose-proportional increase in erlotinib exposure when the TARCEVA dose was
increased from 150 mg to 300 mg. [see DOSAGE AND ADMINISTRATION, DRUG
INTERACTIONS and PATIENT INFORMATION].
Drug Interaction Studies
Co-administration of gemcitabine had no effect on
erlotinib plasma clearance.
CYP3A4 Inhibitors
Co-administration with a strong CYP3A4 inhibitor,
ketoconazole, increased erlotinib AUC by 67%. Co-administration with a combined
CYP3A4 and CYP1A2 inhibitor, ciprofloxacin, increased erlotinib exposure [AUC]
by 39%, and increased erlotinib maximum concentration [Cmax] by 17%. [see Dose
Modifications, DRUG INTERACTIONS].
CYP3A4 Inducers
Pre-treatment with the CYP3A4 inducer rifampicin, for
7-11 days prior to TARCEVA, decreased erlotinib AUC by 58% to 80% [see Dose
Modifications, DRUG INTERACTIONS].
CYP1A2 Inducers or Smoking Tobacco
See Specific Populations Section [see Dose
Modifications, DRUG INTERACTIONS].
Drugs that Increase Gastric pH
Erlotinib solubility is pH dependent and decreases as pH
increases. When a proton pump inhibitor (omeprazole) was co-administered with
TARCEVA the erlotinib exposure [AUC] was decreased by 46% and the erlotinib
maximum concentration [Cmax] was decreased by 61%. When TARCEVA was
administered 2 hours following a 300 mg dose of an H-2 receptor antagonist
(ranitidine), the erlotinib AUC was reduced by 33% and the erlotinib Cmax was
reduced by 54%. When TARCEVA was administered with ranitidine 150 mg twice
daily (at least 10 h after the previous ranitidine evening dose and 2 h before
the ranitidine morning dose), the erlotinib AUC was decreased by 15% and the
erlotinib Cmax was decreased by 17% [see Dose Modifications, DRUG
INTERACTIONS].
Clinical Studies
Non-Small Cell Lung Cancer (NSCLC) - First-Line Treatment
Of Patients With EGFR Mutations
Study 1
The safety and efficacy of TARCEVA as monotherapy for the
first-line treatment of patients with metastatic NSCLC containing EGFR exon 19
deletions or exon 21 (L858R) substitution mutations was demonstrated in Study
1, a randomized, open-label, clinical trial conducted in Europe. One hundred
seventy-four (174) White patients were randomized 1:1 to receive erlotinib 150
mg once daily until disease progression (n = 86) or four cycles of a standard
platinum-based doublet chemotherapy (n = 88); standard chemotherapy regimens
were cisplatin plus gemcitabine, cisplatin plus docetaxel, carboplatin plus
gemcitabine, and carboplatin plus docetaxel. The main efficacy outcome measure
was progression-free survival (PFS) as assessed by the investigator.
Randomization was stratified by EGFR mutation (exon 19 deletion or exon 21
(L858R) substitution) and Eastern Cooperative Oncology Group Performance Status
(ECOG PS) (0 vs. 1 vs. 2). EGFR mutation status for screening and enrollment of
patients was determined by a clinical trials assay (CTA). Tumor samples from
134 patients (69 patients from the erlotinib arm and 65 patients from the
chemotherapy arm) were tested retrospectively by the FDA-approved companion
diagnostic, cobas® EGFR Mutation Test.
Baseline demographics of the overall study population
were: female (72%), White (99%), age ≥ 65 years (51%), ECOG PS 1 (53%),
with ECOG PS 0 (33%), and ECOG PS 2 (14%), current smoker (11%), past-smoker
(20%), and never smoker (69%). The disease characteristics were 93% Stage IV
and 7% Stage IIIb with pleural effusion as classified by the American Joint
Commission on Cancer (AJCC, 6th edition), 93% adenocarcinoma, 66% exon 19
mutation deletions and 34% exon 21 (L858R) point mutation by CTA.
A statistically significant improvement in investigator-determined
PFS (based on RECIST 1.0 or clinical progression) was demonstrated for patients
randomized to erlotinib compared to those randomized to chemotherapy (see Table
6 and Figure 1). Similar results for PFS (based on RECIST 1.0) were observed
for the subgroup evaluated by an independent-review committee (approximately
75% of patients evaluated in Study 1) and in the subgroup of 134 patients (77%
of Study 1 population) with EGFR mutations confirmed by the cobas® EGFR
Mutation Test.
A protocol-specified analysis of overall survival (OS)
conducted at the time of the final analysis of PFS showed no statistically
significant difference between the TARCEVA and chemotherapy arms. At the time
of the data cut-off, 84% of patients in the chemotherapy arm had received at
least one subsequent treatment, of whom 97% received an EGFR-tyrosine kinase
inhibitor. In the TARCEVA arm, 66% of patients had received at least one
subsequent treatment.
Table 6: Efficacy Results (Study 1)
Efficacy Parameter |
Erlotinib
(N = 86) |
Chemotherapy
(N = 88) |
Progression-Free Survival |
Number of Progressions or Deaths |
71 (83%) |
63 (72%) |
Median PFS in Months (95% CI) |
10.4 (8.7, 12.9) |
5.2 (4.6, 6.0) |
Hazard Ratio (95% CI) 1 |
0.34 (0.23, 0.49) |
p-value (unstratified log-rank test) |
< 0.001 |
Overall Survival |
Number of Deaths (%) |
55 (64%) |
54 (61%) |
Median OS in Months (95% CI) |
22.9 (17.0, 26.8) |
19.5 (17.3, 28.4) |
Hazard Ratio (95% CI)1 |
0.93 (0.64, 1.35) |
Objective Response |
Objective Response Rate (95% CI) |
65% (54.1%, 75.1%) |
16% (9.0%, 25.3%) |
1 Unstratified Cox regression model. |
Figure 1: Kaplan-Meier Curves of Investigator-Assessed
PFS in Study 1
In exploratory subgroup
analyses based on EGFR mutation subtype, the hazard ratio (HR) for PFS was 0.27
(95% CI 0.17 to 0.43) in patients with exon 19 deletions and 0.52 (95% CI 0.29
to 0.95) in patients with exon 21 (L858R) substitution. The HR for OS was 0.94 (95%
CI 0.57 to 1.54) in the exon 19 deletion subgroup and 0.99 (95% CI 0.56 to
1.76) in the exon 21 (L858R) substitution subgroup.
NSCLC -Lack Of Efficacy Of TARCEVA
In Maintenance Treatment Of Patients Without EGFR Mutations
Lack of efficacy of TARCEVA for
the maintenance treatment of patients with NSCLC without EGFR activating
mutations was demonstrated in Study 2. Study 2 was a multicenter,
placebo-controlled, randomized trial of 643 patients with advanced NSCLC without
an EGFR exon 19 deletion or exon 21 L858R mutation who had not experienced
disease progression after four cycles of platinum-based chemotherapy. Patients
were randomized 1:1 to receive TARCEVA 150 mg or placebo orally once daily (322
TARCEVA, 321 placebo) until disease progression or unacceptable toxicity.
Following progression on initial therapy, patients were eligible to enter an
open-label phase. Baseline characteristics were as follows: median age 61 years
(35% age ≥ 65 years), 75% male, 77% White, 21% Asian, 28% ECOG PS 0, 72%
ECOG PS 1, 16% never smokers, 58% current smokers, 57% adenocarcinoma, 35% squamous
cell carcinoma, 22% stage IIIB disease not amenable to combined modality
treatment, and 78% stage IV disease. Fifty percent of patients randomized to
TARCEVA entered the open-label phase and received chemotherapy, while 77% of
patients randomized to placebo entered the open-label phase and received
TARCEVA.
The main efficacy outcome was
overall survival (OS). Median OS was 9.7 months in the TARCEVA arm and 9.5
months in the placebo arm; the hazard ratio for OS was 1.02 (95% CI 0.85,
1.22). Median PFS was 3.0 months in the TARCEVA arm and 2.8 months in the
placebo arm; the hazard ratio for PFS was 0.94 (95% CI 0.80, 1.11).
NSCLC - Maintenance Treatment Or
Second/Third Line Treatment
Two randomized, double-blind,
placebo-controlled trials, Studies 3 and 4, examined the efficacy and safety of
TARCEVA administered to patients with metastatic NSCLC as maintenance therapy
after initial treatment with chemotherapy (Study 3) or with disease progression
following initial treatment with chemotherapy (Study 4). Determination of EGFR
mutation status was not required for enrollment.
Study 3
The efficacy and safety of
TARCEVA as maintenance treatment of NSCLC were demonstrated in Study 3, a
randomized, double-blind, placebo-controlled trial conducted in 26 countries,
in 889 patients with metastatic NSCLC whose disease did not progress during
first-line platinum-based chemotherapy. Patients were randomized 1:1 to receive
TARCEVA 150 mg or placebo orally once daily (438 TARCEVA, 451 placebo) until
disease progression or unacceptable toxicity. The primary objective of the
study was to determine if the administration of TARCEVA after standard
platinum-based chemotherapy in the treatment of NSCLC resulted in improved
progression-free survival (PFS) when compared with placebo, in all patients or
in patients with EGFR immunohistochemistry (IHC) positive tumors.
Baseline demographics of the
overall study population were as follows: male (74%), age < 65 years (66%),
ECOG PS 1 (69%), ECOG PS 0 (31%), white (84%), Asian (15%), current smoker
(55%), past-smoker (27%), and never smoker (17%). Disease characteristics were
as follows: Stage IV (75%), Stage IIIb with effusion (25%) as classified by
AJCC (6th edition) with histologic subtypes of adenocarcinoma
including bronchioalveolar (45%), squamous (40%) and large cell (5%); and EGFR
IHC positive (70%), negative (14%), indeterminate (4%), and missing (12%).
Table 7: Efficacy Results (Study 3): (ITT Population)1
Efficacy Parameter |
TARCEVA
(N = 438) |
Placebo
(N = 451) |
Progression-Free Survival (PFS) based on investigator assessment |
Number of Progression or Deaths (%) |
349 (80%) |
400 (89%) |
Median PFS in Months (95% CI) |
2.8 (2.8, 3.1) |
2.6 (1.9, 2.7) |
Hazard Ratio (95% CI) 2 |
0.71 (0.62, 0.82) |
p-value (stratified log-rank test) 2,3 |
p < 0.0001 |
Overall Survival (OS) |
Number of Deaths |
298 (68%) |
350 (78%) |
Median OS in Months (95% CI) |
12.0 (10.6, 13.9) |
11.0 (9.9, 12.1) |
Hazard Ratio (95% CI) 2 |
0.81 (0.70, 0.95) |
p-value (stratified log-rank test) 3 |
0.0088 |
1 Patients with PD prior to randomization were
excluded from PFS and TTP analysis.
2 Univariate Cox regression model.
3 Unstratified log-rank test. |
Figure 2 : depicts the
Kaplan-Meier Curves for Overall Survival (ITT Population)
Figure 2: Kaplan-Meier Curves for Overall Survival (ITT Population)
Study 4
The efficacy and safety of
single-agent TARCEVA was assessed in Study 4, a randomized, double blind,
placebo-controlled trial in 731 patients with locally advanced or metastatic
NSCLC after failure of at least one chemotherapy regimen. Patients were
randomized 2:1 to receive TARCEVA 150 mg or placebo (488 TARCEVA, 243 placebo)
orally once daily until disease progression or unacceptable toxicity. Efficacy
outcome measures included overall survival, response rate, and progression-free
survival (PFS). Duration of response was also examined. The primary endpoint
was survival. The study was conducted in 17 countries.
Baseline demographics of the
overall study population were as follows: male (65%), White (78%), Asian (12%),
Black (4%), age < 65 years (62%), ECOG PS 1 (53%), ECOG PS 0 (13%), ECOG PS
2 (25%), ECOG PS 3 (9%), current or ex-smoker (75%), never smoker (20%), and
exposure to prior platinum therapy (93%). Tumor characteristics were as
follows: adenocarcinoma (50%), squamous (30%), undifferentiated large cell
(9%), and mixed non-small cell (2%).
The results of the study are
shown in Table 8.
Table 8: Efficacy Results (Study 4)
Efficacy Parameter |
TARCEVA
(N = 488) |
Placebo
(N = 243) |
Overall Survival (OS) |
Number of Deaths |
378 (77%) |
209 (86%) |
Median OS in Months (95% CI) |
6.7 (5.5, 7.8) |
4.7 (4.1, 6.3) |
Hazard Ratio (95% CI) 1 |
0.73 (0.61, 0.86) |
p-value (stratified log-rank test)2 |
p < 0.001 |
Progression-Free Survival (PFS) |
Number of Progression or Deaths (%) |
402 (82%) |
211 (87%) |
Median PFS in Months (95% CI) |
2.3 (1.9, 3.3) |
1.8 (1.8, 1.9) |
Hazard Ratio (95% CI)1 |
0.59 (0.50, 0.70) |
Objective Response |
Objective Response Rate (95% CI) |
8.9% (6.4, 12.0) |
0.9% (0.1, 3.4) |
1 Cox regression model with the following
covariates: ECOG performance status, number of prior regimens, prior platinum,
best response to prior chemotherapy.
2 Two-sided log-rank test stratified by ECOG performance status,
number of prior regimens, prior platinum, best response to prior chemotherapy. |
Figure 3 depicts the
Kaplan-Meier curves for overall survival.
Figure 3: Kaplan-Meier
Curves for Overall Survival of Patients by Treatment Group in Study 4
NSCLC - Lack Of Efficacy Of TARCEVA
Administered Concurrently With Chemotherapy
Results from two, multicenter,
placebo-controlled, randomized, trials in over 1000 patients conducted in
first-line patients with locally advanced or metastatic NSCLC showed no
clinical benefit with the concurrent administration of TARCEVA with platinum-based
chemotherapy [carboplatin and paclitaxel (TARCEVA, N = 526) or gemcitabine and
cisplatin (TARCEVA, N = 580)].
Pancreatic Cancer -TARCEVA
Administered Concurrently With Gemcitabine
The efficacy and safety of TARCEVA in combination with
gemcitabine as a first-line treatment was assessed in Study 5, a randomized,
double-blind, placebo-controlled trial in 569 patients with locally advanced,
unresectable or metastatic pancreatic cancer. Patients were randomized 1:1 to
receive TARCEVA (100 mg or 150 mg) or placebo once daily on a continuous
schedule plus gemcitabine by intravenous infusion (1000 mg/m², Cycle 1 -Days 1,
8, 15, 22, 29, 36 and 43 of an 8-week cycle; Cycle 2 and subsequent cycles
-Days 1, 8 and 15 of a 4-week cycle [the approved dose and schedule for
pancreatic cancer, see the gemcitabine package insert]). TARCEVA or placebo was
taken orally once daily until disease progression or unacceptable toxicity. The
primary endpoint was survival. Secondary endpoints included response rate, and
progression-free survival (PFS). Duration of response was also examined. The
study was conducted in 18 countries. A total of 285 patients were randomized to
receive gemcitabine plus TARCEVA (261 patients in the 100 mg cohort and 24
patients in the 150 mg cohort) and 284 patients were randomized to receive
gemcitabine plus placebo (260 patients in the 100 mg cohort and 24 patients in
the 150 mg cohort). Too few patients were treated in the 150 mg cohort to draw
conclusions.
In the 100 mg cohort, baseline
demographics of the overall study population were as follows: male (52%), white
(88%), Asian (7%), black (2%), age < 65 years (53%), ECOG PS 1 (51%), ECOG
PS 0 (32%), and ECOG PS 2 (17%). There was a slightly larger proportion of
females in the TARCEVA arm (51%) compared with the placebo arm (44%). The
median time from initial diagnosis to randomization was approximately 1.0
month. The majority of the patients (76%) had distant metastases at baseline
and 24% had locally advanced disease.
The results of the study are
shown in Table 9.
Table 9: Efficacy Results:
TARCEVA 100 mg Cohort (Study 5)
Efficacy Parameter |
TARCEVA + Gemcitabine
(N = 261) |
Placebo + Gemcitabine
(N = 260) |
Overall Survival (OS) |
Number of Deaths |
250 |
254 |
Median OS in Months (95% CI) |
6.5 (6.0, 7.4) |
6.0 (5.1, 6.7) |
Hazard Ratio (95% CI) 1 |
0.81 (0.68, 0.97) |
p-value (stratified log-rank test) 2 |
0.028 |
Progression-Free Survival (PFS) |
Number of Progression or Deaths (%) |
225 |
232 |
Median PFS in Months (95% CI) |
3.8 (3.6, 4.9) |
3.6 (3.3, 3.8) |
Hazard Ratio (95% CI)1 |
0.76 (0.64, 0.92) |
Objective Response |
Objective Response Rate (95% CI) |
8.6% (5.4, 12.9) |
7.9% (4.8, 12.0) |
1 Cox regression model with the following
covariates: ECOG performance status and extent of disease.
2 Two-sided log-rank test stratified by ECOG performance status and
extent of disease. |
Survival was evaluated in the
intent-to-treat population. Figure 4 depicts the Kaplan-Meier curves for
overall survival in the 100 mg cohort. The primary survival and PFS analyses
were two-sided log-rank tests stratified by ECOG performance status and extent
of disease.
Figure 4: Kaplan-Meier Curves for Overall Survival:
100 mg Cohort in Study 5