CLINICAL PHARMACOLOGY
Mechanism Of Action
TNF is a naturally occurring
cytokine that is involved in normal inflammatory and immune responses. It plays
an important role in the inflammatory processes of RA, polyarticular JIA, PsA
and AS and the resulting joint pathology. In addition, TNF plays a role in the
inflammatory process of PsO. Elevated levels of TNF are found in involved
tissues and fluids of patients with RA, JIA, PsA, AS, and PsO.
Two distinct receptors for TNF
(TNFRs), a 55 kilodalton protein (p55) and a 75 kilodalton protein (p75), exist
naturally as monomeric molecules on cell surfaces and in soluble forms.
Biological activity of TNF is dependent upon binding to either cell surface
TNFR.
Etanercept products are dimeric
soluble forms of the p75 TNF receptor that can bind TNF molecules. Etanercept
products inhibit binding of TNF-α and TNF-β (lymphotoxin alpha
[LT-α]) to cell surface TNFRs, rendering TNF biologically inactive. In in
vitro studies, large complexes of etanercept with TNF-α were not detected
and cells expressing transmembrane TNF (that binds etanercept products) are not
lysed in the presence or absence of complement.
Pharmacodynamics
Etanercept products can
modulate biological responses that are induced or regulated by TNF, including
expression of adhesion molecules responsible for leukocyte migration (eg,
E-selectin, and to a lesser extent, intercellular adhesion molecule-1
[ICAM-1]), serum levels of cytokines (eg, IL-6), and serum levels of matrix
metalloproteinase-3 (MMP-3 or stromelysin). Etanercept products have been shown
to affect several animal models of inflammation, including murine
collagen-induced arthritis.
Pharmacokinetics
After administration of 25 mg
of etanercept by a single SC injection to 25 patients with RA, a mean ±
standard deviation half-life of 102 ± 30 hours was observed with a clearance of
160 ± 80 mL/hr. A maximum serum concentration (Cmax) of 1.1 ± 0.6 mcg/mL and
time to Cmax of 69 ± 34 hours was observed in these patients following a single
25 mg dose. After 6 months of twice weekly 25 mg doses in these same RA
patients, the mean Cmax was 2.4 ± 1.0 mcg/mL (N = 23). Patients exhibited a
2-to 7-fold increase in peak serum concentrations and approximately 4-fold
increase in AUC0-72 hr (range 1-to 17-fold) with repeated dosing. Serum concentrations
in patients with RA have not been measured for periods of dosing that exceed 6
months.
In another study, serum concentration profiles at
steady-state were comparable among patients with RA treated with 50 mg
etanercept once weekly and those treated with 25 mg etanercept twice weekly.
The mean (± standard deviation) Cmax, Cmin, and partial AUC were 2.4 ± 1.5
mcg/mL, 1.2 ± 0.7 mcg/mL, and 297 ± 166 mcgââ¬Â¢h/mL, respectively, for patients
treated with 50 mg etanercept once weekly (N = 21); and 2.6 ± 1.2 mcg/mL, 1.4 ±
0.7 mcg/mL, and 316 ± 135 mcgââ¬Â¢h/mL for patients treated with 25 mg etanercept
twice weekly (N = 16).
Patients with JIA (ages 4 to 17 years) were administered
0.4 mg/kg of etanercept twice weekly (up to a maximum dose of 50 mg per week)
for up to 18 weeks. The mean serum concentration after repeated SC dosing was
2.1 mcg/mL, with a range of 0.7 to 4.3 mcg/mL. Limited data suggest that the
clearance of etanercept is reduced slightly in children ages 4 to 8 years.
Population pharmacokinetic analyses predict that the pharmacokinetic
differences between the regimens of 0.4 mg/kg twice weekly and 0.8 mg/kg once
weekly in JIA patients are of the same magnitude as the differences observed
between twice weekly and weekly regimens in adult RA patients.
The mean (± SD) serum steady-state trough concentrations
for the 50 mg QW dosing in adult PsO patients were 1.5 ± 0.7 mcg/mL.
In clinical studies with etanercept, pharmacokinetic
parameters were not different between men and women and did not vary with age
in adult patients. The pharmacokinetics of etanercept were unaltered by
concomitant MTX in RA patients. No formal pharmacokinetic studies have been
conducted to examine the effects of renal or hepatic impairment on etanercept
disposition.
Clinical Studies
Adult Rheumatoid Arthritis
The safety and efficacy of etanercept were assessed in
four randomized, double-blind, controlled studies. The results of all four
trials were expressed in percentage of patients with improvement in RA using
ACR response criteria.
Study I evaluated 234 patients with active RA who were
≥ 18 years old, had failed therapy with at least one but no more than
four disease-modifying antirheumatic drugs (DMARDs) (e.g., hydroxychloroquine,
oral or injectable gold, MTX, azathioprine, D-penicillamine, sulfasalazine), and
had ≥ 12 tender joints, ≥ 10 swollen joints, and either erythrocyte
sedimentation rate (ESR) ≥ 28 mm/hr, C-reactive protein (CRP) > 2.0
mg/dL, or morning stiffness for ≥ 45 minutes. Doses of 10 mg or 25 mg
etanercept or placebo were administered SC twice a week for 6 consecutive
months.
Study II evaluated 89 patients and had similar inclusion
criteria to Study I except that patients in Study II had additionally received
MTX for at least 6 months with a stable dose (12.5 to 25 mg/week) for at least
4 weeks and they had at least 6 tender or painful joints. Patients in Study II
received a dose of 25 mg etanercept or placebo SC twice a week for 6 months in
addition to their stable MTX dose.
Study III compared the efficacy of etanercept to MTX in patients with active RA. This study
evaluated 632 patients who were ≥ 18 years old with early (≤3 years disease duration) active RA, had never received treatment with MTX, and had ≥ 12 tender joints, ≥ 10 swollen joints, and either ESR ≥ 28 mm/hr, CRP > 2.0 mg/dL, or morning stiffness for ≥ 45 minutes. Doses of 10 mg or 25 mg etanercept were administered SC twice a week for 12 consecutive months. The study was unblinded after all patients had completed at least 12 months (and a median of 17.3 months) of therapy. The majority of patients remained in the study on the treatment to which they were randomized through 2 years, after which they entered an extension study and received open-label 25 mg etanercept. MTX tablets (escalated from 7.5 mg/week to a maximum of 20 mg/week over the first 8 weeks of the trial) or placebo tablets were given once a week on the same day as the injection of placebo or etanercept doses, respectively.
Study IV evaluated 682 adult patients with active RA of 6
months to 20 years duration (mean of 7 years) who had an inadequate response to
at least one DMARD other than MTX. Forty-three percent of patients had
previously received MTX for a mean of 2 years prior to the trial at a mean dose
of 12.9 mg. Patients were excluded from this study if MTX had been discontinued
for lack of efficacy or for safety considerations. The patient baseline
characteristics were similar to those of patients in Study I. Patients were
randomized to MTX alone (7.5 to 20 mg weekly, dose escalated as described for
Study III; median dose 20 mg), etanercept alone (25 mg twice weekly), or the
combination of etanercept and MTX initiated concurrently (at the same doses as
above). The study evaluated ACR response, Sharp radiographic score, and safety.
Clinical Response
A higher percentage of patients treated with etanercept
and etanercept in combination with MTX achieved ACR 20, ACR 50, and ACR 70
responses and Major Clinical Responses than in the comparison groups. The
results of Studies I, II, and III are summarized in Table 6. The results of
Study IV are summarized in Table 7.
Table 6: ACR Responses in Placebo-and
Active-Controlled Trials (Percent of Patients)
Response |
Placebo Controlled |
Active Controlled |
Study I |
Study II |
Study III |
Placebo
N=80 |
Etanercepta
N= 78 |
MTX/ Placebo
N= 30 |
MTX/ Etanercepta
N= 59 |
MTX
N=217 |
Etanercepta
N= 207 |
ACR 20 |
Month 3 |
23% |
62%b |
33% |
66%b |
56% |
62% |
Month 6 |
11% |
59%b |
27% |
71%b |
58% |
65% |
Month 12 |
NA |
NA |
NA |
NA |
65% |
72% |
ACR 50 |
Month 3 |
8% |
41%b |
0% |
42%b |
24% |
29% |
Month 6 |
5% |
40%b |
3% |
39%b |
32% |
40% |
Month 12 |
NA |
NA |
NA |
NA |
43% |
49% |
ACR 70 |
Month 3 |
4% |
15%b |
0% |
15%b |
7% |
13%c |
Month 6 |
1% |
15%b |
0% |
15%b |
14% |
21%c |
Month 12 |
NA |
NA |
NA |
NA |
22% |
25% |
a 25 mg etanercept SC twice weekly
b p< 0.01, etanercept vs placebo
c p< 0.05, etanercept vs MTX |
Table 7: Study IV Clinical Efficacy Results: Comparison of MTX vs Etanercept vs Etanercept in Combination
With MTX in Patients With Rheumatoid Arthritis of 6 Months to 20 Years Duration (Percent of Patients)
Endpoint |
MTX
(N= 228) |
Etanercept
(N= 223) |
Etanercept/MTX
(N= 231) |
ACR Nab |
Month 12 |
40% |
47% |
63%c |
ACR 20 |
Month 12 |
59% |
66% |
75%c |
ACR 50 |
Month 12 |
36% |
43% |
63%c |
ACR 70 |
Month 12 |
17% |
22% |
40%c |
Major Clinical Responsed |
6% |
10% |
24%c |
aValues are medians.
bACR N is the percent improvement based on the same core variables
used in defining ACR 20, ACR 50, and ACR 70.
cp < 0.05 for comparisons of etanercept/MTX vs etanercept alone
or MTX alone.
dMajor clinical response is achieving an ACR 70 response for a
continuous 6-month period. |
The time course for ACR 20
response rates for patients receiving placebo or 25 mg etanercept in Studies I
and II is summarized in Figure 1. The time course of responses to etanercept in
Study III was similar.
FigureÃÂ 1 :Time Course of ACR 20 Responses
Among patients receiving
etanercept, the clinical responses generally appeared within 1 to 2 weeks after
initiation of therapy and nearly always occurred by 3 months. A dose response
was seen in Studies I and III: 25 mg etanercept was more effective than 10 mg
(10 mg was not evaluated in Study II). Etanercept was significantly better than
placebo in all components of the ACR criteria as well as other measures of RA
disease activity not included in the ACR response criteria, such as morning
stiffness.
In Study III, ACR response
rates and improvement in all the individual ACR response criteria were
maintained through 24 months of etanercept therapy. Over the 2-year study, 23%
of etanerceptâ⬙s patients achieved a major clinical response, defined as
maintenance of an ACR 70 response over a 6-month period.
The results of the components
of the ACR response criteria for Study I are shown in Table 8. Similar results
were observed for etanercept -treated patients in Studies II and III.
Table 8: Components of ACR Response in Study I
Parameter (median) |
Placebo
N=80 |
Etanercepta
N=78 |
Baseline |
3 Months |
Baseline |
3 Months* |
Number of tender jointsb |
34.0 |
29.5 |
31.2 |
10.0f |
Number of swollen jointsc |
24.0 |
22.0 |
23.5 |
12.6f |
Physician global assessmentd |
7.0 |
6.5 |
7.0 |
3.0f |
Patient global assessmentd |
7.0 |
7.0 |
7.0 |
3.0f |
Paind |
6.9 |
6.6 |
6.9 |
2.4f |
Disability indexe |
1.7 |
1.8 |
1.6 |
1.0f |
ESR (mm/hr) |
31.0 |
32.0 |
28.0 |
15.5f |
CRP (mg/dL) |
2.8 |
3.9 |
3.5 |
0.9f |
*Results at 6 months showed similar improvement.
a25 mg etanercept SC twice weekly.
bScale 0-71.
cScale 0-68.
dVisual analog scale: 0 = best; 10 = worst.
eHealth Assessment Questionnaire: 0 = best; 3 = worst; includes
eight categories: dressing and grooming, arising, eating, walking, hygiene,
reach, grip, and activities.
fp < 0.01, etanercept vs placebo, based on mean percent change
from baseline. |
After discontinuation of
etanercept, symptoms of arthritis generally returned within a month. Reintroduction
of treatment with etanercept after discontinuations of up to 18 months resulted
in the same magnitudes of response as in patients who received etanercept
without interruption of therapy, based on results of open-label studies.
Continued durable responses
were seen for over 60 months in open-label extension treatment trials when
patients received etanercept without interruption. A substantial number of
patients who initially received concomitant MTX or corticosteroids were able to
reduce their doses or discontinue these concomitant therapies while maintaining
their clinical responses.
Physical Function Response
In Studies I, II, and III,
physical function and disability were assessed using the Health Assessment
Questionnaire (HAQ). Additionally, in Study III, patients were administered the
SF36 Health Survey. In Studies I and II, patients treated with 25 mg etanercept
twice weekly showed greater improvement from baseline in the HAQ score
beginning in month 1 through month 6 in comparison to placebo (p < 0.001)
for the HAQ disability domain (where 0 = none and 3 = severe). In Study I, the
mean improvement in the HAQ score from baseline to month 6 was 0.6 (from 1.6 to
1.0) for the 25 mg etanercept group and 0 (from 1.7 to 1.7) for the placebo
group. In Study II, the mean improvement from baseline to month 6 was 0.6 (from
1.5 to 0.9) for the etanercept /MTX group and 0.2 (from 1.3 to 1.2) for the
placebo/MTX group. In Study III, the mean improvement in the HAQ score from
baseline to month 6 was 0.7 (from 1.5 to 0.7) for 25 mg etanercept twice
weekly. All subdomains of the HAQ in Studies I and III were improved in
patients treated with etanercept.
In Study III, patients treated
with 25 mg etanercept twice weekly showed greater improvement from baseline in
SF-36 physical component summary score compared to etanercept 10 mg twice weekly
and no worsening in the SF-36 mental component summary score. In open-label
studies of etanercept, improvements in physical function and disability
measures have been maintained for up to 4 years.
In Study IV, median HAQ scores improved from baseline
levels of 1.8, 1.8, and 1.8 to 1.1, 1.0, and 0.6 at 12 months in the MTX,
etanercept, and etanercept /MTX combination treatment groups, respectively
(combination versus both MTX and etanercept, p < 0.01). Twenty-nine percent
of patients in the MTX alone treatment group had an improvement of HAQ of at
least 1 unit versus 40% and 51% in etanercept alone and etanercept /MTX
combination treatment groups, respectively.
Radiographic Response
In Study III, structural joint damage was assessed
radiographically and expressed as change in Total Sharp Score (TSS) and its
components, the erosion score and joint space narrowing (JSN) score.
Radiographs of hands/wrists and forefeet were obtained at baseline, 6 months,
12 months, and 24 months and scored by readers who were unaware of treatment
group. The results are shown in Table 9. A significant difference for change in
erosion score was observed at 6 months and maintained at 12 months.
Table 9: Mean Radiographic Change Over 6 and 12 Months
in Study III
|
|
MTX |
25 mg Etanercept |
MTX/ Etanercept (95% Confidence Interval*) |
P Value |
12 Months |
Total Sharp Score |
1.59 |
1.00 |
0.59 (-0.12, 1.30) |
0.1 |
Erosion Score |
1.03 |
0.47 |
0.56 (0.11, 1.00) |
0.002 |
JSN Score |
0.56 |
0.52 |
0.04 (-0.39, 0.46) |
0.5 |
6 Months |
Total Sharp Score |
1.06 |
0.57 |
0.49 (0.06, 0.91) |
0.001 |
Erosion Score |
0.68 |
0.30 |
0.38 (0.09, 0.66) |
0.001 |
JSN Score |
0.38 |
0.27 |
0.11 (-0.14, 0.35) |
0.6 |
* 95% confidence intervals for
the differences in change scores between MTX and etanercept. |
Patients continued on the
therapy to which they were randomized for the second year of Study III. Seventy-two
percent of patients had x-rays obtained at 24 months. Compared to the patients
in the MTX group, greater inhibition of progression in TSS and erosion score
was seen in the 25 mg etanercept group, and, in addition, less progression was
noted in the JSN score.
In the open-label extension of
Study III, 48% of the original patients treated with 25 mg etanercept have been
evaluated radiographically at 5 years. Patients had continued inhibition of
structural damage, as measured by the TSS, and 55% of them had no progression
of structural damage. Patients originally treated with MTX had further
reduction in radiographic progression once they began treatment with
etanercept.
In Study IV, less radiographic
progression (TSS) was observed with etanercept in combination with MTX compared
with etanercept alone or MTX alone at month 12 (Table 10). In the MTX treatment
group, 55% of patients experienced no radiographic progression (TSS change
≤ 0.0) at 12 months compared to 63% and 76% in etanercept alone
and etanercept /MTX combination treatment groups, respectively.
Table 10: Mean Radiographic
Change in Study IV at 12 Months (95% Confidence Interval)
|
MTX
(N=212)* |
Etanercept
(N=212)* |
Etanercept/MTX
(N=218)* |
Total Sharp Score (TSS) |
2.80
(1.08, 4.51) |
0.52a
(-0.10, 1.15) |
-0.54b,c
(-1.00, -0.07) |
Erosion Score (ES) |
1.68
(0.61, 2.74) |
0.21a
(-0.20, 0.61) |
-0.30b
(-0.65, 0.04) |
Joint Space Narrowing (JSN) Score |
1.12
(0.34, 1.90) |
0.32
(0.00, 0.63) |
-0.23b,c
(-0.45, -0.02) |
*Analyzed radiographic ITT population.
ap < 0.05 for comparison of etanercept vs MTX.
bp < 0.05 for comparison of etanercept/MTX vs MTX.
cp < 0.05 for comparison of etanercept/MTX vs etanercept. |
Once Weekly Dosing
The safety and efficacy of 50
mg etanercept (two 25 mg SC injections) administered once weekly were evaluated
in a double-blind, placebo-controlled study of 420 patients with active RA.
Fifty-three patients received placebo, 214 patients received 50 mg etanercept
once weekly, and 153 patients received 25 mg etanercept twice weekly. The
safety and efficacy profiles of the two etanercept treatment groups were
similar.
Polyarticular Juvenile
Idiopathic Arthritis (JIA)
The safety and efficacy of
etanercept were assessed in a 2-part study in 69 children with polyarticular
JIA who had a variety of JIA onset types. Patients ages 2 to 17 years with
moderately to severely active polyarticular JIA refractory to or intolerant of
MTX were enrolled; patients remained on a stable dose of a single nonsteroidal
anti-inflammatory drug and/or prednisone (≤0.2 mg/kg/day or 10 mg maximum). In part 1, all patients received 0.4 mg/kg
(maximum 25 mg per dose) etanercept SC twice weekly. In part 2, patients with a clinical response at day 90 were randomized to remain on etanercept or receive placebo for 4 months and assessed for disease flare. Responses were measured using the JIA Definition of Improvement (DOI), defined as ≥ 30% improvement in at least three of six and ≥ 30% worsening in no more
than one of the six JIA core set criteria, including active joint count, limitation of motion, physician and patient/parent global assessments, functional assessment, and ESR. Disease flare was defined as a ≥ 30% worsening in three of the six JIA core set criteria and ≥ 30% improvement in not more than one of the six JIA core set criteria and a minimum of two active joints.
In part 1 of the study, 51 of69 (74%) patients demonstrated a clinical response and entered part 2. In part 2, 6 of 25 (24%) patients remaining on etanercept experienced a disease flare
compared to 20 of 26 (77%) patients receiving placebo (p = 0.007). From the start
of part 2, the median time to flare was ≥ 116 days for patients who
received etanercept and 28 days for patients who received placebo. Each
component of the JIA core set criteria worsened in the arm that received
placebo and remained stable or improved in the arm that continued on
etanercept. The data suggested the possibility of a higher flare rate among
those patients with a higher baseline ESR. Of patients who demonstrated a
clinical response at 90 days and entered part 2 of the study, some of the
patients remaining on etanercept continued to improve from month 3 through
month 7, while those who received placebo did not improve.
The majority of JIA patients who developed a disease
flare in part 2 and reintroduced etanercept treatment up to 4 months after
discontinuation re-responded to etanercept therapy in open-label studies. Most
of the responding patients who continued etanercept therapy without
interruption have maintained responses for up to 48 months.
Studies have not been done in patients with polyarticular
JIA to assess the effects of continued etanercept therapy in patients who do
not respond within 3 months of initiating etanercept therapy, or to assess the
combination of etanercept with MTX.
Psoriatic Arthritis
The safety and efficacy of etanercept were assessed in a
randomized, double-blind, placebo-controlled study in 205 patients with PsA.
Patients were between 18 and 70 years of age and had active PsA (≥ 3
swollen joints and ≥ 3 tender joints) in one or more of the following
forms: (1) distal interphalangeal (DIP) involvement (N = 104); (2)
polyarticular arthritis (absence of rheumatoid nodules and presence of
psoriasis; N = 173); (3) arthritis mutilans (N = 3); (4) asymmetric psoriatic
arthritis (N = 81); or (5) ankylosing spondylitis-like (N = 7). Patients also had
plaque psoriasis with a qualifying target lesion ≥ 2 cm in diameter.
Patients on MTX therapy at enrollment (stable for ≥ 2 months) could
continue at a stable dose of ≤ 25 mg/week MTX. Doses of 25 mg etanercept
or placebo were administered SC twice a week during the initial 6month
double-blind period of the study. Patients continued to receive blinded therapy
in an up to 6-month maintenance period until all patients had completed the
controlled period. Following this, patients received open-label 25 mg etanercept
twice a week in a 12-month extension period.
Compared to placebo, treatment with etanercept resulted
in significant improvements in measures of disease activity (Table 11).
Table 11: Components of Disease Activity in Psoriatic
Arthritis
Parameter (median) |
Placebo
N= 104 |
Etanercepta
N= 101 |
Baseline |
6 Months |
Baseline |
6 Months |
Number of tender jointsb |
17.0 |
13.0 |
18.0 |
5.0 |
Number of swollen jointsc |
12.5 |
9.5 |
13.0 |
5.0 |
Physician global assessmentd |
3.0 |
3.0 |
3.0 |
1.0 |
Patient global assessmentd |
3.0 |
3.0 |
3.0 |
1.0 |
Morning stiffness (minutes) |
60 |
60 |
60 |
15 |
Paind |
3.0 |
3.0 |
3.0 |
1.0 |
Disability indexe |
1.0 |
0.9 |
1.1 |
0.3 |
CRP (mg/dL)f |
1.1 |
1.1 |
1.6 |
0.2 |
ap < 0.001 for all comparisons between
etanercept and placebo at 6 months.
bScale 0-78.
cScale 0-76.
dLikert scale: 0 = best; 5 = worst.
eHealth Assessment Questionnaire: 0 = best; 3 = worst; includes
eight categories: dressing and grooming, arising, eating, walking, hygiene,
reach, grip, and activities.
fNormal range: 0-0.79 mg/dL. |
Among patients with PsA who
received etanercept, the clinical responses were apparent at the time of the
first visit (4 weeks) and were maintained through 6 months of therapy. Responses
were similar in patients who were or were not receiving concomitant MTX therapy
at baseline. At 6 months, the ACR 20/50/70 responses were achieved by 50%, 37%,
and 9%, respectively, of patients receiving etanercept, compared to 13%, 4%,
and 1%, respectively, of patients receiving placebo. Similar responses were
seen in patients with each of the subtypes of PsA, although few patients were
enrolled with the arthritis mutilans and ankylosing spondylitis-like subtypes.
The results of this study were similar to those seen in an earlier
single-center, randomized, placebo-controlled study of 60 patients with PsA.
The skin lesions of psoriasis
were also improved with etanercept, relative to placebo, as measured by
percentages of patients achieving improvements in the Psoriasis Area and
Severity Index (PASI). Responses increased over time, and at 6 months, the
proportions of patients achieving a 50% or 75% improvement in the PASI were 47%
and 23%, respectively, in the etanercept group (N = 66), compared to 18% and
3%, respectively, in the placebo group (N = 62). Responses were similar in
patients who were or were not receiving concomitant MTX therapy at baseline.
Radiographic Response
Radiographic changes were also
assessed in the PsA study. Radiographs of hands and wrists were obtained at
baseline and months 6, 12, and 24. A modified Total Sharp Score (TSS), which
included distal interphalangeal joints (ie, not identical to the modified TSS
used for RA) was used by readers blinded to treatment group to assess the
radiographs. Some radiographic features specific to PsA (eg, pencil-and-cup
deformity, joint space widening, gross osteolysis, and ankylosis) were included
in the scoring system, but others (eg, phalangeal tuft resorption,
juxtaarticular and shaft periostitis) were not.
Most patients showed little or no change in the modified
TSS during this 24-month study (median change of 0 in both patients who
initially received etanercept or placebo). More placebo-treated patients
experienced larger magnitudes of radiographic worsening (increased TSS)
compared to etanercept treatment during the controlled period of the study. At
12 months, in an exploratory analysis, 12% (12 of 104) of placebo patients
compared to none of the 101 of etanercept-treated patients had increases of 3
points or more in TSS. Inhibition of radiographic progression was maintained in
patients who continued on etanercept during the second year. Of the patients
with 1-year and 2-year x-rays, 3% (2 of 71) had increases of 3 points or more
in TSS at 1 and 2 years.
Physical Function Response
In the PsA study, physical function and disability were
assessed using the HAQ Disability Index (HAQ-DI) and the SF-36 Health Survey.
Patients treated with 25 mg etanercept twice weekly showed greater improvement
from baseline in the HAQ-DI score (mean decreases of 54% at both months 3 and
6) in comparison to placebo (mean decreases of 6% at both months 3 and 6) (p
< 0.001). At months 3 and 6, patients treated with etanercept showed greater
improvement from baseline in the SF-36 physical component summary score
compared to patients treated with placebo, and no worsening in the SF-36 mental
component summary score. Improvements in physical function and disability
measures were maintained for up to 2 years through the open-label portion of
the study.
Ankylosing Spondylitis
The safety and efficacy of etanercept were assessed in a
randomized, double-blind, placebo-controlled study in 277 patients with active
AS. Patients were between 18 and 70 years of age and had AS as defined by the
modified New York Criteria for Ankylosing Spondylitis. Patients were to have
evidence of active disease based on values of ≥ 30 on a 0-100 unit Visual
Analog Scale (VAS) for the average of morning stiffness duration and intensity,
and two of the following three other parameters: a) patient global assessment,
b) average of nocturnal and total back pain, and c) the average score on the
Bath Ankylosing Spondylitis Functional Index (BASFI). Patients with complete
ankylosis of the spine were excluded from study participation. Patients taking
hydroxychloroquine, sulfasalazine, methotrexate, or prednisone (≤ 10
mg/day) could continue these drugs at stable doses for the duration of the
study. Doses of 25 mg etanercept or placebo were administered SC twice a week
for 6 months.
The primary measure of efficacy was a 20% improvement in
the Assessment in Ankylosing Spondylitis (ASAS) response criteria. Compared to
placebo, treatment with etanercept resulted in improvements in the ASAS and
other measures of disease activity (Figure 2 and Table 12).
Figure 2 : ASAS 20 Responses in Ankylosing Spondylitis
At 12 weeks, the ASAS 20/50/70
responses were achieved by 60%, 45%, and 29%, respectively, of patients
receiving etanercept, compared to 27%, 13%, and 7%, respectively, of patients
receiving placebo (p ≤ 0.0001, etanercept vs placebo). Similar responses
were seen at Week 24. Responses were similar between those patients receiving
concomitant therapies at baseline and those who were not. The results of this
study were similar to those seen in a single-center, randomized,
placebo-controlled study of 40 patients and a multicenter, randomized,
placebo-controlled study of 84 patients with AS.
Table 12: Components of Ankylosing Spondylitis Disease
Activity
Median values at time points |
Placebo
N=139 |
Etanercepta
N=138 |
Baseline |
6 Months |
Baseline |
6 Months |
ASAS response criteria Patient global assessmentb |
63 |
56 |
63 |
36 |
Back painc |
62 |
56 |
60 |
34 |
BASFId |
56 |
55 |
52 |
36 |
Inflammatione |
64 |
57 |
61 |
33 |
Acute phase reactants CRP (mg/dL)f |
2.0 |
1.9 |
1.9 |
0.6 |
Spinal mobility (cm): Modified Schober’s test |
3.0 |
2.9 |
3.1 |
3.3 |
Chest expansion |
3.2 |
3.0 |
3.3 |
3.9 |
Occiput-to-wall measurement |
5.3 |
6.0 |
5.6 |
4.5 |
ap < 0.0015 for all comparisons between
etanercept and placebo at 6 months. P values for continuous endpoints were
based on percent change from baseline.
bMeasured on a Visual Analog Scale (VAS) with 0 = “none” and 100 =
“severe”.
cAverage of total nocturnal and back pain scores, measured on a VAS
with 0 = “no pain” and 100 = “most severe pain”.
dBath Ankylosing Spondylitis Functional Index (BASFI), average of 10
questions.
eInflammation represented by the average of the last 2 questions on
the 6-question Bath Ankylosing Spondylitis Disease Activity Index (BASDAI).
fC-reactive protein (CRP) normal range: 0-1.0 mg/dL. |
Adult Plaque Psoriasis
The safety and efficacy of
etanercept were assessed in two randomized, double-blind, placebo-controlled
studies in adults with chronic stable PsO involving ≥ 10% of the body
surface area, a minimum Psoriasis Area and Severity Index (PASI) score of 10
and who had received or were candidates for systemic antipsoriatic therapy or
phototherapy. Patients with guttate, erythrodermic, or pustular psoriasis and
patients with severe infections within 4 weeks of screening were excluded from
study. No concomitant major antipsoriatic therapies were allowed during the
study.
Study I evaluated 672 patients
who received placebo or etanercept SC at doses of 25 mg once a week, 25 mg
twice a week, or 50 mg twice a week for 3 months. After 3 months, patients
continued on blinded treatments for an additional 3 months during which time
patients originally randomized to placebo began treatment with blinded
etanercept at 25 mg twice weekly (designated as placebo/etanercept in Table
13); patients originally randomized to etanercept continued on the originally
randomized dose (designated as etanercept/etanercept groups in Table 13).
Study II evaluated 611 patients
who received placebo or etanercept SC at doses of 25 mg or 50 mg twice a week
for 3 months. After 3 months of randomized, blinded treatment, patients in all
three arms began receiving open-label etanercept at 25 mg twice weekly for 9 additional
months.
Response to treatment in both studies was assessed after
3 months of therapy and was defined as the proportion of patients who achieved
a reduction in PASI score of at least 75% from baseline. The PASI is a
composite score that takes into consideration both the fraction of body surface
area affected and the nature and severity of psoriatic changes within the
affected regions (induration, erythema and scaling).
Other evaluated outcomes included the proportion of
patients who achieved a score of “clear” or “minimal” by the Static Physician
Global Assessment (sPGA) and the proportion of patients with a reduction of
PASI of at least 50% from baseline. The sPGA is a 6-category scale ranging from
“5 = severe” to “0 = none” indicating the physicianâ⬙s overall assessment of the
PsO severity focusing on induration, erythema and scaling. Treatment success of
“clear” or “minimal” consisted of none or minimal elevation in plaque, up to
faint red coloration in erythema and none or minimal fine scale over < 5% of
the plaque.
Patients in all treatment groups and in both studies had
a median baseline PASI score ranging from 15 to 17, and the percentage of
patients with baseline sPGA classifications ranged from 54% to 66% for
moderate, 17% to 26% for marked and 1% to 5% for severe. Across all treatment
groups, the percentage of patients who previously received systemic therapy for
PsO ranged from 61% to 65% in Study I and 71% to 75% in Study II, and those who
previously received phototherapy ranged from 44% to 50% in Study I and 72% to
73% in Study II.
More patients randomized to etanercept than placebo
achieved at least a 75% reduction from baseline PASI score (PASI 75) with a
dose response relationship across doses of 25 mg once a week, 25 mg twice a
week and 50 mg twice a week (Tables 13 and 14). The individual components of
the PASI (induration, erythema and scaling) contributed comparably to the
overall treatment-associated improvement in PASI.
Table 13: Study I Outcomes at 3 and 6 Months
|
Placebo/ Etanercept 25 mg BIW
(N= 168) |
Etanercept/Etanercept |
25 mg QW
(N= 169) |
25 mg BIW
(N= 167) |
50 mg BIW
(N= 168) |
3 Months |
PASI 75 n (%) |
6 (4%) |
23 (14%)a |
53 (32%)b |
79 (47%)b |
Difference (95% CI) |
|
10% (4, 16) |
28% (21, 36) |
43% (35, 52) |
sPGA, ‘clear’ or ‘minimal’ n (%) |
8 (5%) |
36 (21%)b |
53 (32%)b |
79 (47%)b |
Difference (95% CI) |
|
17% (10, 24) |
27% (19, 35) |
42% (34, 50) |
PASI 50 n (%) |
24 (14%) |
62 (37%)b |
90 (54%)b |
119 (71%)b |
Difference (95% CI) |
|
22% (13, 31) |
40% (30, 49) |
57% (48, 65) |
6 Months PASI 75 n (%) |
55 (33%) |
36 (21%) |
68 (41%) |
90 (54%) |
ap = 0.001 compared with placebo.
bp < 0.0001 compared with placebo. |
Table 14: Study II Outcomes at 3 Months
|
Placebo
(N= 204) |
Etanercept |
25 mg BIW
(N= 204) |
50 mg BIW
(N= 203) |
PASI 75 n (%) |
6 (3%) |
66 (32%)a |
94 (46%)a |
Difference (95% CI) |
|
29% (23, 36) |
43% (36, 51) |
sPGA, “clear” or minimal” n (%) |
7 (3%) |
75 (37%)a |
109 (54%)a |
Difference (95% CI) |
|
34% (26, 41) |
50% (43, 58) |
PASI 50 n (%) |
18 (9%) |
124 (61%)a |
147 (72%)a |
Difference (95% CI) |
|
52% (44, 60) |
64% (56, 71) |
ap < 0.0001 compared with placebo. |
Among PASI 75 achievers in both studies, the median time
to PASI 50 and PASI 75 was approximately 1 month and approximately 2 months,
respectively, after the start of therapy with either 25 or 50 mg twice a week.
In Study I, patients who achieved PASI 75 at month 6 were
entered into a study drug withdrawal and retreatment period. Following
withdrawal of study drug, these patients had a median duration of PASI 75 of
between 1 and 2 months.
In Study I, among patients who were PASI 75 responders at
3 months, retreatment with their original blinded etanercept dose after
discontinuation of up to 5 months resulted in a similar proportion of
responders as in the initial double-blind portion of the study.
In Study II, most patients initially randomized to 50 mg
twice a week continued in the study after month 3 and had their etanercept dose
decreased to 25 mg twice a week. Of the 91 patients who were PASI 75 responders
at month 3, 70 (77%) maintained their PASI 75 response at month 6.
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