CLINICAL PHARMACOLOGY
Mechanism Of Action
Neratinib is an intracellular
kinase inhibitor that irreversibly binds to epidermal growth factor receptor
(EGFR), HER2, and HER4. In vitro, neratinib reduces EGFR and HER2
autophosphorylation, downstream MAPK and AKT signaling pathways, and showed
antitumor activity in EGFR and/or HER2 expressing carcinoma cell lines.
Neratinib human metabolites M3, M6, M7 and M11 inhibited the activity of EGFR,
HER2, and HER4 in vitro. In vivo, oral administration of neratinib inhibited
tumor growth in mouse xenograft models with tumor cell lines expressing HER2
and EGFR.
Pharmacodynamics
Cardiac Electrophysiology
The effect of NERLYNX on the
QTc interval was evaluated in a randomized, placebo and positive-controlled,
double-blind, single-dose, crossover study in 60 healthy subjects. At 2.4-fold
the therapeutic exposures of NERLYNX, there was no clinically relevant effect
on the QTc interval.
Pharmacokinetics
Neratinib exhibits a non-linear
PK profile with less than dose proportional increase of AUC with the increasing
daily dose over the range of 40 to 400 mg.
Absorption
The neratinib and major active
metabolites M3, M6 and M7 peak concentrations are reached in the range of 2 to
8 hours after oral administration.
Effect Of Food
The food-effect assessment was
conducted in healthy volunteers who received NERLYNX 240 mg under fasting
conditions and with high-fat food (approximately 55% fat, 31% carbohydrate, and
14% protein) or standard breakfast (approximately 50% carbohydrate, 35% fat,
and 15% protein). A high-fat meal increased neratinib Cmax and AUCinf by
1.7-fold (90% CI: 1.1-2.7) and 2.2-fold (90% CI: 1.4-3.5), respectively. A
standard breakfast increased the Cmax and AUCinf by 1.2-fold (90% CI:
0.97-1.42) and 1.1-fold (90% CI: 1.021.24), respectively. [See DOSAGE AND
ADMINISTRATION]
Distribution
In patients, following multiple
doses of NERLYNX, the mean (%CV) apparent volume of distribution at
steady-state (Vss/F) was 6433 (19%) L. In vitro protein binding of neratinib in
human plasma was greater than 99% and independent of concentration. Neratinib
bound predominantly to human serum albumin and human alpha-1 acid glycoprotein.
Elimination
Following 7 days of daily 240
mg oral doses of NERLYNX in healthy subjects, the mean (%CV) plasma half-life
of neratinib, M3, M6, and M7 was 14.6 (38%), 21.6 (77%), 13.8 (50%) and 10.4
(33%) hours, respectively. The mean elimination half-life of neratinib ranged
from 7 to 17 hours following a single oral dose in patients. Following multiple
doses of NERLYNX at once-daily 240 mg in cancer patients, the mean (%CV) CL/F
after first dose and at steady state (day 21) were 216 (34%) and 281 (40%)
L/hour, respectively.
Metabolism
Neratinib is metabolized
primarily in the liver by CYP3A4 and to a lesser extent by flavin-containing
monooxygenase (FMO).
After oral administration of
NERLYNX, neratinib represents the most prominent component in plasma. At steady
state after 240 mg daily oral doses of NERLYNX in a healthy subject study
(n=25), the systemic exposures (AUC) of the active metabolites M3, M6, M7 and
M11were 15%, 33%, 22% and 4% of the systemic neratinib exposure (AUC)
respectively.
Excretion
After oral administration of
200 mg (0.83 times of approved recommended dosage) radiolabeled neratinib oral
formulation, fecal excretion accounted for approximately 97.1% and urinary
excretion accounted for 1.13% of the total dose. Sixty-one percent of the
excreted radioactivity was recovered within 96 hours and 98% was recovered
after 10 days.
Specific Populations
Age, gender, race, and renal
function do not have a clinically significant effect on neratinib
pharmacokinetics.
Patients With Hepatic
Impairment
Neratinib is mainly metabolized
in the liver. Single doses of 120 mg NERLYNX were evaluated in non-cancer patients
with chronic hepatic impairment (n=6 each in Child Pugh Class A, B, and C) and
in healthy subjects (n=9) with normal hepatic function. Neratinib exposures in
the patients with Child Pugh Class A (mild impairment) and Child Pugh Class B
(moderate impairment) were similar to that in normal healthy volunteers.
Patients with severe hepatic impairment (Child Pugh Class C) had neratinib Cmax
and AUC increased by 273% and 281%, respectively, as compared to the normal
hepatic function controls. [see DOSAGE AND ADMINISTRATION and Use In Specific
Populations].
Drug Interaction Studies
Gastric Acid Reducing Agents
NERLYNX solubility decreases
with increasing GI tract pH values. Drugs that alter the pH values of the GI
tract may alter the solubility of neratinib and hence its absorption and
systemic exposure. When multiple doses of lansoprazole (30 mg daily), a proton
pump inhibitor, were co-administered with a single 240 mg oral dose of NERLYNX,
the neratinib Cmax and AUC decreased by 71% and 65%, respectively. When a
single oral dose of 240 mg NERLYNX was administered 2 hours following a daily
dose of 300 mg ranitidine, an H2 receptor antagonist, the neratinib Cmax and
AUC were reduced by 57% and 48%, respectively. When a single oral dose of 240
mg NERLYNX was administered 2 hours prior to 150 mg ranitidine twice daily
(administered in the morning and evening, approximately 12 hours apart), the
neratinib Cmax and AUC were reduced by 44% and 32%, respectively. [See DOSAGE
AND ADMINISTRATION and DRUG INTERACTIONS].
Strong And Moderate CYP3A4
Inhibitors
Concomitant use of ketoconazole
(400 mg once-daily for 5 days), a strong inhibitor of CYP3A4, with a single
oral 240 mg NERLYNX dose in healthy subjects (n=24) increased neratinib Cmax by
321% and AUC by 481%.
The effect of moderate CYP3A4
inhibition has not been studied. Given neratinib is predominantly metabolized
by the CYP3A4 pathway and had a significant exposure change with strong CYP3A4
inhibition, the potential impact on NERLYNX safety from concomitant use with
moderate CYP3A4 inhibitors warrants consideration [see DRUG INTERACTIONS].
Strong And Moderate CYP3A4
Inducers
Concomitant use of rifampin, a
strong inducer of CYP3A4, with a single oral 240 mg NERLYNX dose in healthy
subjects (n=24) reduced neratinib Cmax by 76% and AUC by 87%. The AUC of active
metabolites M6 and M7 were also reduced by 37-49% when compared to NERLYNX
administered alone.
The effect of moderate CYP3A4
induction has not been studied. Given neratinib is predominantly metabolized by
the CYP3A4 pathway and had a significant exposure change with strong CYP3A4
induction, the potential impact on NERLYNX efficacy from concomitant use with
moderate CYP3A4 inducers warrants consideration [see DRUG INTERACTIONS].
Effect Of NERLYNX On P-gp
Transporters
Concomitant use of digoxin (a
single 0.5 mg oral dose), a P-gp substrate, with multiple oral doses of NERLYNX
240 mg in healthy subjects (n=18) increased the mean digoxin Cmax by 54% and
AUC by 32% [see DRUG INTERACTIONS].
Clinical Studies
Extended Adjuvant Treatment In Breast Cancer
The safety and efficacy of NERLYNX were investigated in
the ExteNET trial (NCT00878709), a multicenter, randomized, double-blind,
placebo-controlled study of NERLYNX after adjuvant treatment with a trastuzumab
based therapy in women with HER2-positive breast cancer.
A total of 2840 patients with early-stage (Stage 1 to 3c)
HER2-positive breast cancer within two years of completing treatment with
adjuvant trastuzumab was randomized to receive either NERLYNX (n=1420) or
placebo (n=1420). Randomization was stratified by the following factors:
hormone receptor status, nodal status (0, 1-3 vs 4 or more positive nodes) and
whether trastuzumab was given sequentially versus concurrently with
chemotherapy. NERLYNX 240 mg or placebo was given orally once daily for one
year. The major efficacy outcome measure was invasive disease-free survival
(iDFS) defined as the time between the date of randomization to the first
occurrence of invasive recurrence (local/regional, ipsilateral, or
contralateral breast cancer), distant recurrence, or death from any cause, with
2 years and 28 days of follow-up.
Patient demographics and tumor characteristics were
generally balanced between treatment arms. Patients had a median age of 52
years (range 23 to 83) and 12% of patients were 65 or older. The majority of
patients were White (81%), and most patients (99.7%) had an ECOG performance
status of 0 or 1. Fifty-seven percent (57%) of patients had hormone receptor
positive disease (defined as ER-positive and/or PR-positive), 24% were node
negative, 47% had one to three positive nodes and 30% had four or more positive
nodes. Ten percent (10%) of patients had Stage I disease, 41% had Stage II
disease and 31% had Stage III disease. The majority of patients (81%) were
enrolled within one year of completion of trastuzumab treatment. Median time
from the last adjuvant trastuzumab treatment to randomization was 4.4 months in
the NERLYNX arm versus 4.6 months in the placebo arm. Median duration of
treatment was 11.6 months in the NERLYNX arm vs. 11.8 months in the placebo
arm.
The efficacy results from the ExteNET trial are
summarized in Table 8 and Figure 1.
Table 8: Efficacy iDFS Results for the ITT Population
Number of Events/ Total N (%) |
iDFS at 24 months* (%, 95% CI) |
Stratified†, HR (95% CI) |
P-value‡ |
NERLYNX |
Placebo |
NERLYNX |
Placebo |
67/1420 (4.7) |
106/1420 (7.5) |
94.2 (92.6, 95.4) |
91.9 (90.2, 93.2) |
0.66 (0.49, 0.90) |
0.008 |
CI= Confidence Interval;
HR=Hazard Ratio; iDFS=Invasive Disease Free-Survival; ITT=Intent to Treat
* Kaplan-Meier estimate
† Stratified by prior trastuzumab (concurrent vs.
sequential), nodal status (0-3 positive nodes vs.≥4 positive nodes), and
ER/PR status (positive vs. negative)
‡ Stratified log-rank test |
Figure 1: iDFS in the
ExteNET Trial -ITT Population
Table 9: Subgroup Analyses*
Population |
Number of Events/Total N (%) |
iDFS at 24 months† (%, 95% CI) |
Unstratified HR (95% CI) |
NERLYNX |
Placebo |
NERLYNX |
Placebo |
Hormone Receptor Status |
Positive |
29/816 (3.6) |
63/815 (7.7) |
95.6 (93.8, 96.9) |
91.5 (89.2, 93.3) |
0.49 (0.31, 0.75) |
Negative |
38/604 (6.3) |
43/605 (7.1) |
92.2 (89.4, 94.3) |
92.4 (89.8, 94.3) |
0.93 (0.60, 1.43) |
Nodal Status |
Negative |
7/335 (2.1) |
11/336 (3.3) |
97.2 (94.1, 98.7) |
96.5 (93.7, 98.0) |
0.72 (0.26, 1.83) |
1-3 Positive Nodes |
31/664 (4.7) |
47/664 (7.1) |
94.4 (92.2, 96.1) |
92.4 (90.0, 94.2) |
0.68 (0.43, 1.07) |
≥4 Positive Nodes |
29/421 (6.9) |
48/420 (114) |
91.4 (87.9, 94.0) |
87.3 (83.4, 90.2) |
0.62 (0.39, 0.97) |
Prior Trastuzumab |
Concurrent |
49/884 (5.5) |
66/886 (7.4) |
93.2 (91.0, 94.8) |
92.0 (89.9, 93.7) |
0.80 (0.55, 1.16) |
Sequential |
18/536 (3.4) |
40/534 (7.5) |
95.8 (93.4, 97.3) |
91.6 (88.7, 93.8) |
0.46 (0.26, 0.78) |
Completion of Prior Trastuzumab |
<1 year |
58/1152 (5.0) |
95/1145 (8.3) |
93.8 (92.0, 95.2) |
90.9 (89.0, 92.5) |
0.63 (0.45, 0.88) |
1-2 years |
9/262 (3.4) |
11/270 (4.1) |
95.8 (92.0, 97.8) |
95.7 (92.3, 97.6) |
0.92 (0.37, 2.22) |
CI=Confidence Interval;
HR=Hazard Ratio
* Exploratory analyses without adjusting multiple comparisons
† Kaplan-Meier estimate |
Approximately 75% of patients
were re-consented for extended follow-up beyond 24 months. Observations with
missing data were censored at the last date of assessment. This exploratory
analysis suggests that the iDFS results at 5 years are consistent with the
2-year iDFS results observed in ExteNET. At the time of the iDFS analysis, 2%
of patients had died, and overall survival data were immature.