CLINICAL PHARMACOLOGY
Mechanism Of Action
Infliximab products neutralize the biological activity of
TNFα by binding with high affinity to the soluble and transmembrane forms
of TNFα and inhibit binding of TNFα with its receptors. Infliximab
products do not neutralize TNFβ (lymphotoxin-α), a related cytokine
that utilizes the same receptors as TNFα. Biological activities attributed
to TNFα include: induction of proinflammatory cytokines such as IL-1 and
IL-6, enhancement of leukocyte migration by increasing endothelial layer
permeability and expression of adhesion molecules by endothelial cells and
leukocytes, activation of neutrophil and eosinophil functional activity,
induction of acute phase reactants and other liver proteins, as well as tissue
degrading enzymes produced by synoviocytes and/or chondrocytes. Cells
expressing transmembrane TNFα bound by infliximab products can be lysed in
vitro or in vivo. Infliximab products inhibit the functional activity of
TNFα in a wide variety of in vitro bioassays utilizing human fibroblasts,
endothelial cells, neutrophils, B and T lymphocytes and epithelial cells. The
relationship of these biological response markers to the mechanism(s) by which
infliximab products exert their clinical effects is unknown. Anti-TNFα
antibodies reduce disease activity in the cotton-top tamarin colitis model, and
decrease synovitis and joint erosions in a murine model of collagen-induced
arthritis. Infliximab products prevent disease in transgenic mice that develop
polyarthritis as a result of constitutive expression of human TNFα, and
when administered after disease onset, allows eroded joints to heal.
Pharmacodynamics
Elevated concentrations of TNFα have been found in
involved tissues and fluids of patients with rheumatoid arthritis, Crohn's
disease, ulcerative colitis, ankylosing spondylitis, psoriatic arthritis and
plaque psoriasis. In rheumatoid arthritis, treatment with infliximab products
reduced infiltration of inflammatory cells into inflamed areas of the joint as
well as expression of molecules mediating cellular adhesion [E-selectin,
intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion
molecule-1 (VCAM-1)], chemoattraction [IL-8 and monocyte chemotactic protein
(MCP-1)] and tissue degradation [matrix metalloproteinase (MMP) 1 and 3]. In
Crohn's disease, treatment with infliximab products reduced infiltration of
inflammatory cells and TNFα production in inflamed areas of the intestine,
and reduced the proportion of mononuclear cells from the lamina propria able to
express TNFα and interferon. After treatment with infliximab products,
patients with rheumatoid arthritis or Crohn's disease exhibited decreased
levels of serum IL-6 and C-reactive protein (CRP) compared to baseline.
Peripheral blood lymphocytes from infliximab product-treated patients showed no
significant decrease in number or in proliferative responses to in vitro mitogenic
stimulation when compared to cells from untreated patients. In psoriatic
arthritis, treatment with infliximab products resulted in a reduction in the
number of T-cells and blood vessels in the synovium and psoriatic skin lesions
as well as a reduction of macrophages in the synovium. In plaque psoriasis,
infliximab products treatment may reduce the epidermal thickness and
infiltration of inflammatory cells. The relationship between these
pharmacodynamic activities and the mechanism(s) by which infliximab products
exert their clinical effects is unknown.
Pharmacokinetics
In adults, single intravenous infusions of 3 mg/kg to 20
mg/kg of infliximab showed a linear relationship between the dose administered
and the maximum serum concentration. The volume of distribution at steady state
was independent of dose and indicated that infliximab was distributed primarily
within the vascular compartment. Pharmacokinetic results for single doses of 3
mg/kg to 10 mg/kg in rheumatoid arthritis, 5 mg/kg in Crohn's disease, and 3 mg/kg
to 5 mg/kg in plaque psoriasis indicate that the median terminal half-life of
infliximab is 7.7 to 9.5 days.
Following an initial dose of infliximab, repeated
infusions at 2 and 6 weeks resulted in predictable concentration-time profiles
following each treatment. No systemic accumulation of infliximab occurred upon
continued repeated treatment with 3 mg/kg or 10 mg/kg at 4-or 8week intervals.
Development of antibodies to infliximab increased infliximab clearance. At 8
weeks after a maintenance dose of 3 to 10 mg/kg of infliximab, median
infliximab serum concentrations ranged from approximately 0.5 to 6 mcg/mL;
however, infliximab concentrations were not detectable ( < 0.1 mcg/mL) in
patients who became positive for antibodies to infliximab. No major differences
in clearance or volume of distribution were observed in patient subgroups
defined by age, weight, or gender. It is not known if there are differences in
clearance or volume of distribution in patients with marked impairment of
hepatic or renal function.
Infliximab pharmacokinetic characteristics (including
peak and trough concentrations and terminal half-life) were similar in
pediatric (aged 6 to 17 years) and adult patients with Crohn's disease
following the administration of 5 mg/kg of infliximab.
Population pharmacokinetic analysis showed that in
children with JRA with a body weight of up to 35 kg receiving 6 mg/kg of
infliximab and children with JRA with body weight greater than 35 kg up to
adult body weight receiving 3mg/kg infliximab product, the steady state area
under the concentration curve (AUCss) was similar to that observed in adults
receiving 3 mg/kg of infliximab.
Clinical Studies
Crohn's Disease
Active Crohn's Disease
The safety and efficacy of single and multiple doses of
infliximab were assessed in 2 randomized, double-blind, placebo-controlled
clinical studies in 653 patients with moderate to severely active Crohn's
disease [Crohn's Disease Activity Index (CDAI) ≥ 220 and ≤ 400] with
an inadequate response to prior conventional therapies. Concomitant stable
doses of aminosalicylates, corticosteroids and/or immunomodulatory agents were
permitted and 92% of patients continued to receive at least one of these
medications.
In the single-dose trial of 108 patients, 16% (4/25) of
placebo patients achieved a clinical response (decrease in CDAI ≥ 70
points) at Week 4 vs. 81% (22/27) of patients receiving 5 mg/kg infliximab
(P < 0.001, two-sided, Fisher's Exact test). Additionally, 4% (1/25) of
placebo patients and 48% (13/27) of patients receiving 5 mg/kg of infliximab
achieved clinical remission (CDAI < 150) at Week 4.
In a multidose trial (ACCENT I [Study Crohn's I]), 545
patients received 5 mg/kg at Week 0 and were then randomized to one of three
treatment groups; the placebo maintenance group received placebo at Weeks 2 and
6, and then every 8 weeks; the 5 mg/kg maintenance group received 5 mg/kg at
Weeks 2 and 6, and then every 8 weeks; and the 10 mg/kg maintenance group
received 5 mg/kg at Weeks 2 and 6, and then 10 mg/kg every 8 weeks. Patients in
response at Week 2 were randomized and analyzed separately from those not in responses
at Week 2. Corticosteroid taper was permitted after Week 6.
At Week 2, 57% (311/545) of patients were in clinical
response. At Week 30, a significantly greater proportion of these patients in
the 5 mg/kg and 10 mg/kg maintenance groups achieved clinical remission
compared to patients in the placebo maintenance group (Table 3).
Additionally, a significantly greater proportion of
patients in the 5 mg/kg and 10 mg/kg maintenance groups of infliximab were in
clinical remission and were able to discontinue corticosteroid use compared to
patients in the placebo maintenance group at Week 54 (Table 3).
Table 3 : Clinical remission and steroid withdrawal
|
Single 5-mg/kg Dosea |
Three-Dose Inductionb |
Placebo Maintenance |
Infliximab Maintenance q 8wks |
5 mg/kg |
10 mg/kg |
Week 30
|
Clinical remission |
25/102 |
41/104 |
48/105 |
|
25% |
39% |
46% |
P-valuec |
|
0.022 |
0.001 |
Week 54
|
Patients in remission able to |
6/54 |
14/56 |
18/53 |
discontinue corticosteroid used |
11% |
25% |
34% |
P-valuec |
|
0.059 |
0.005 |
a Infliximab at Week 0
b Infliximab 5 mg/kg administered at Weeks 0, 2 and 6
c P-values represent pairwise comparisons to placebo
d Of those receiving corticosteroids at baseline |
Patients in infliximab
maintenance groups (5 mg/kg and 10 mg/kg) had a longer time to loss of response
than patients in the placebo maintenance group (Figure 1). At Weeks 30 and 54,
significant improvement from baseline was seen among the 5 mg/kg and 10 mg/kg
groups treated with infliximab compared to the placebo group in the
disease-specific inflammatory bowel disease questionnaire (IBDQ), particularly
the bowel and systemic components, and in the physical component summary score
of the general health-related quality of life questionnaire SF36.
Figure 1 : Kaplan-Meier
estimate of the proportion of patients who had not lost response through Week
54
In a subset of 78 patients who
had mucosal ulceration at baseline and who participated in an endoscopic
substudy, 13 of 43 patients in infliximab maintenance group had endoscopic
evidence of mucosal healing compared to 1 of 28 patients in the placebo group
at Week 10. Of the patients treated with infliximab showing mucosal healing at
Week 10, 9 of 12 patients also showed mucosal healing at Week 54.
Patients who achieved a
response and subsequently lost response were eligible to receive infliximab on
an episodic basis at a dose that was 5 mg/kg higher than the dose to which they
were randomized. The majority of such patients responded to the higher dose.
Among patients who were not in response at Week 2, 59% (92/157) of maintenance
patients on infliximab responded by Week 14 compared to 51% (39/77) of placebo
maintenance patients. Among patients who did not respond by Week 14, additional
therapy did not result in significantly more responses [see DOSAGE AND
ADMINISTRATION].
Fistulizing Crohn's Disease
The safety and efficacy of
infliximab were assessed in 2 randomized, double-blind, placebo-controlled
studies in patients with fistulizing Crohn's disease with fistula(s) that were
of at least 3 months duration. Concurrent use of stable doses of corticosteroids,
5-aminosalicylates, antibiotics, MTX, 6-MP and/or AZA was permitted.
In the first trial, 94 patients received 3 doses of
either placebo or infliximab at Weeks 0, 2 and 6. Fistula response ( ≥ 50%
reduction in number of enterocutaneous fistulas draining upon gentle
compression on at least 2 consecutive visits without an increase in medication
or surgery for Crohn's disease) was seen in 68% (21/31) of patients in the 5
mg/kg infliximab group (P=0.002) and 56% (18/32) of patients in the 10 mg/kg
infliximab group (P=0.021) vs. 26% (8/31) of patients in the placebo arm. The
median time to onset of response and median duration of response in patients
treated with infliximab was 2 and 12 weeks, respectively. Closure of all fistulas
was achieved in 52% patients treated with infliximab compared with 13% of
placebo-treated patients (P < 0.001).
In the second trial (ACCENT II [Study Crohn's II]),
patients who were enrolled had to have at least 1 draining enterocutaneous
(perianal, abdominal) fistula. All patients received 5 mg/kg of infliximab at
Weeks 0, 2 and 6. Patients were randomized to placebo or 5 mg/kg maintenance
with infliximab at Week 14. Patients received maintenance doses at Week 14 and
then every 8 weeks through Week 46. Patients who were in fistula response
(fistula response was defined the same as in the first trial) at both Weeks 10
and 14 were randomized separately from those not in response. The primary
endpoint was time from randomization to loss of response among those patients
who were in fistula response.
Among the randomized patients (273 of the 296 initially
enrolled), 87% had perianal fistulas and 14% had abdominal fistulas. Eight
percent also had rectovaginal fistulas. Greater than 90% of the patients had
received previous immunosuppressive and antibiotic therapy.
At Week 14, 65% (177/273) of patients were in fistula
response. Patients randomized to maintenance with infliximab had a longer time
to loss of fistula response compared to the placebo maintenance group (Figure
2). At Week 54, 38% (33/87) of patients treated with infliximab had no draining
fistulas compared with 22% (20/90) of placebo-treated patients (P=0.02).
Compared to placebo maintenance, patients on maintenance treatment with
infliximab had a trend toward fewer hospitalizations.
Figure 2 : Life table estimates of the proportion of
patients who had not lost fistula response through Week 54
Patients who achieved a fistula
response and subsequently lost response were eligible to receive maintenance
therapy with infliximab at a dose that was 5 mg/kg higher than the dose to
which they were randomized. Of the placebo maintenance patients, 66% (25/38)
responded to 5 mg/kg infliximab, and 57% (12/21) of maintenance patients on
infliximab responded to 10 mg/kg.
Patients who had not achieved a
response by Week 14 were unlikely to respond to additional doses of infliximab.
Similar proportions of patients
in either group developed new fistulas (17% overall) and similar numbers
developed abscesses (15% overall).
Pediatric Crohn's Disease
The safety and efficacy of
infliximab were assessed in a randomized, open-label study (Study Peds Crohn's)
in 112 pediatric patients aged 6 to 17 years old with moderately to severely
active Crohn's disease and an inadequate response to conventional therapies.
The median age was 13 years and the median Pediatric Crohn's Disease Activity
Index (PCDAI) was 40 (on a scale of 0 to 100). All patients were required to be
on a stable dose of 6-MP, AZA, or MTX; 35% were also receiving corticosteroids
at baseline.
All patients received induction
dosing of 5 mg/kg of infliximab at Weeks 0, 2, and 6. At Week 10, 103 patients
were randomized to a maintenance regimen of 5 mg/kg of infliximab given either every
8 weeks or every 12 weeks.
At Week 10, 88% of patients were in clinical response
(defined as a decrease from baseline in the PCDAI score of ≥ 15 points and
total PCDAI score of ≤ 30 points), and 59% were in clinical remission
(defined as PCDAI score of ≤ 10 points).
The proportion of pediatric patients achieving clinical
response at Week 10 compared favorably with the proportion of adults achieving
a clinical response in Study Crohn's I. The study definition of clinical
response in Study Peds Crohn's was based on the PCDAI score, whereas the CDAI
score was used in the adult Study Crohn's I.
At both Week 30 and Week 54, the proportion of patients
in clinical response was greater in the every 8-week treatment group than in
the every 12-week treatment group (73% vs. 47% at Week 30, and 64% vs. 33% at
Week 54). At both Week 30 and Week 54, the proportion of patients in clinical
remission was also greater in the every 8-week treatment group than in the
every 12week treatment group (60% vs. 35% at Week 30, and 56% vs. 24% at Week
54), (Table 4).
For patients in Study Peds Crohn's receiving
corticosteroids at baseline, the proportion of patients able to discontinue
corticosteroids while in remission at Week 30 was 46% for the every 8-week
maintenance group and 33% for the every 12-week maintenance group. At Week 54,
the proportion of patients able to discontinue corticosteroids while in
remission was 46% for the every 8-week maintenance group and 17% for the every
12-week maintenance group.
Table 4 : Response and remission in study peds Crohn's
|
5 mg/kg Infliximab |
Every 8 Week Treatment Group |
Every 12 Week Treatment Group |
Patients randomized |
52 |
51 |
Clinical Responsea |
Week 30 |
73%d |
47% |
Week 54 |
64%d |
33% |
Clinical Remissionb |
Week 30 |
60%c |
35% |
Week 54 |
56%d |
24% |
a Defined as a decrease from baseline in the PCDAI score of
≥ 15 points and total score of ≤ 30 points.
b Defined as a PCDAI score of ≤ 10 points.
c P-value < 0.05
d P-value < 0.01 |
Ulcerative Colitis
The safety and efficacy of infliximab were assessed in 2
randomized, double-blind, placebo-controlled clinical studies in 728 patients
with moderately to severely active ulcerative colitis (UC) (Mayo score5
6 to 12 [of possible range 0 to 12], Endoscopy subscore ≥ 2) with an
inadequate response to conventional oral therapies (Studies UC I and UC II).
Concomitant treatment with stable doses of aminosalicylates, corticosteroids
and/or immunomodulatory agents was permitted. Corticosteroid taper was
permitted after Week 8. Patients were randomized at Week 0 to receive either
placebo, 5 mg/kg infliximab or 10 mg/kg infliximab at Weeks 0, 2, 6, and every
8 weeks thereafter through Week 46 in Study UC I, and at Weeks 0, 2, 6, and
every 8 weeks thereafter through Week 22 in Study UC II. In Study UC II, patients
were allowed to continue blinded therapy to Week 46 at the investigator's
discretion.
Patients in Study UC I had
failed to respond or were intolerant to oral corticosteroids, 6-MP, or AZA.
Patients in Study UC II had failed to respond or were intolerant to the above
treatments and/or aminosalicylates. Similar proportions of patients in Studies
UC I and UC II were receiving corticosteroids (61% and 51%, respectively),
6-MP/AZA (49% and 43%) and aminosalicylates (70% and 75%) at baseline. More
patients in Study UC II than UC I were taking solely aminosalicylates for UC
(26% vs. 11%, respectively). Clinical response was defined as a decrease from
baseline in the Mayo score by ≥ 30% and ≥ 3 points, accompanied by a
decrease in the rectal bleeding subscore of ≥ 1 or a rectal bleeding
subscore of 0 or 1.
Clinical Response, Clinical
Remission, And Mucosal Healing
In both Study UC I and Study UC
II, greater percentages of patients in both infliximab groups achieved clinical
response, clinical remission and mucosal healing than in the placebo group.
Each of these effects was maintained through the end of each trial (Week 54 in
Study UC I, and Week 30 in Study UC II). In addition, a greater proportion of
patients in infliximab groups demonstrated sustained response and sustained
remission than in the placebo groups (Table 5).
Of patients on corticosteroids
at baseline, greater proportions of patients in groups treated with infliximab
were in clinical remission and able to discontinue corticosteroids at Week 30 compared
with the patients in the placebo treatment groups (22% in infliximab treatment
groups vs. 10% in placebo group in Study UC I; 23% in infliximab treatment
groups vs. 3% in placebo group in Study UC II). In Study UC I, this effect was
maintained through Week 54 (21% in infliximab treatment groups vs. 9% in
placebo group). The infliximab-associated response was generally similar in the
5 mg/kg and 10 mg/kg dose groups.
Table 5 : Response, remission and mucosal healing in
ulcerative colitis studies
|
Study UC I |
Study UC II |
Placebo |
5 mg/kg Infliximab |
10 mg/kg Infliximab |
Placebo |
5 mg/kg Infliximab |
10 mg/kg Infliximab |
Patients randomized |
121 |
121 |
122 |
123 |
121 |
120 |
Clinical Responsea,d
|
Week 8 |
37% |
69%* |
62%* |
29% |
65%* |
69%* |
Week 30 |
30% |
52%* |
51%** |
26% |
47%* |
60%* |
Week 54 |
20% |
45%* |
44%* |
NA |
NA |
NA |
Sustained Responsed
|
(Clinical response at both Week 8 and 30) |
23% |
49%* |
46%* |
15% |
41%* |
53%* |
(Clinical response at both Week 8, 30 and 54) |
14% |
39%* |
37%* |
NA |
NA |
NA |
Clinical Remissionb,d
|
Week 8 |
15% |
39%* |
32%** |
6% |
34%* |
28%* |
Week 30 |
16% |
34%** |
37%* |
11% |
26%** |
36%* |
Week 54 |
17% |
35%** |
34%** |
NA |
NA |
NA |
Sustained Remissiond
|
(Clinical remission at both Week 8 and 30) |
8% |
23%** |
26%* |
2% |
15%* |
23%* |
(Clinical remission at Weeks 8, 30 and 54) |
7% |
20%** |
20%** |
NA |
NA |
NA |
Mucosal Healingc,d |
Week 8 |
34% |
62%* |
59%* |
31% |
60%* |
62%* |
Week 30 |
25% |
50%* |
49%* |
30% |
46%** |
57%* |
Week 54 |
18% |
45%* |
47%* |
NA |
NA |
NA |
* P < 0.001, ** P < 0.01
a Defined as a decrease from baseline in the Mayo score by
≥ 30% and ≥ 3 points, accompanied by a decrease in the rectal
bleeding subscore of ≥ 1 or a rectal bleeding subscore of 0 or 1. (The
Mayo score consists of the sum of four subscores:
stool frequency, rectal bleeding, physician's global assessment and endoscopy
findings.)
b Defined as a Mayo score ≤ 2 points, no individual subscore
> 1.
c Defined as a 0 or 1 on the endoscopy subscore of the Mayo score.
d Patients who had a prohibited change in medication, had an
ostomy or colectomy, or discontinued study infusions due to lack of efficacy
are considered to not be in clinical response, clinical remission or mucosal
healing from the time of the event onward. |
The improvement with infliximab
was consistent across all Mayo subscores through Week 54 (Study UC I shown in
Table 6; Study UC II through Week 30 was similar).
Table 6 : Proportion of
patients in Study US I with Mayo subscores indicating inactive or mild disease
through Week 54
|
Study UC I |
Placebo
(n=121) |
Infliximab |
5 mg/kg
(n=121) |
10 mg/kg
(n=122) |
Stool frequency |
Baseline |
17% |
17% |
10% |
Week 8 |
35% |
60% |
58% |
Week 30 |
35% |
51% |
53% |
Week 54 |
31% |
52% |
51% |
Rectal bleeding |
Baseline |
54% |
40% |
48% |
Week 8 |
74% |
86% |
80% |
Week 30 |
65% |
74% |
71% |
Week 54 |
62% |
69% |
67% |
Physician’s Global Assessment |
Baseline |
4% |
6% |
3% |
Week 8 |
44% |
74% |
64% |
Week 30 |
36% |
57% |
55% |
Week 54 |
26% |
53% |
53% |
Endoscopy findings |
Baseline |
0% |
0% |
0% |
Week 8 |
34% |
62% |
59% |
Week 30 |
26% |
51% |
52% |
Week 54 |
21% |
50% |
51% |
Rheumatoid Arthritis
The safety and efficacy of
infliximab were assessed in 2 multicenter, randomized, double-blind, pivotal
trials: ATTRACT (Study RA I) and ASPIRE (Study RA II). Concurrent use of stable
doses of folic acid, oral corticosteroids ( ≤ 10 mg/day) and/or non-steroidal
anti-inflammatory drugs (NSAIDs) was permitted.
Study RA I was a
placebo-controlled study of 428 patients with active rheumatoid arthritis
despite treatment with MTX. Patients enrolled had a median age of 54 years,
median disease duration of 8.4 years, median swollen and tender joint count of
20 and 31 respectively, and were on a median dose of 15 mg/wk of MTX. Patients
received either placebo + MTX or one of 4 doses/schedules of the infliximab +
MTX: 3 mg/kg or 10 mg/kg infliximab by intravenous of infusion at Weeks
0, 2 and 6 followed by additional infusions every 4 or 8 weeks in combination
with MTX.
Study RA II was a placebo-controlled study of 3 active
treatment arms in 1004 MTX naïve patients of 3 or fewer years' duration active
rheumatoid arthritis. Patients enrolled had a median age of 51 years with a
median disease duration of 0.6 years, median swollen and tender joint count of
19 and 31, respectively, and > 80% of patients had baseline joint erosions.
At randomization, all patients received MTX (optimized to 20 mg/wk by Week 8)
and either placebo, 3 mg/kg or 6 mg/kg of infliximab at Weeks 0, 2, and 6 and
every 8 weeks thereafter.
Data on use of infliximab products without concurrent MTX
are limited [see ADVERSE REACTIONS].
Clinical Response
In Study RA I, all doses/schedules of infliximab + MTX
resulted in improvement in signs and symptoms as measured by the American
College of Rheumatology response criteria (ACR 20) with a higher percentage of
patients achieving an ACR 20, 50 and 70 compared to placebo + MTX (Table 7).
This improvement was observed at Week 2 and maintained through Week 102.
Greater effects on each component of the ACR 20 were observed in all patients
treated with infliximab + MTX compared to placebo + MTX (Table 8). More
patients treated with infliximab reached a major clinical response than
placebo-treated patients (Table 7). In Study RA II, after 54 weeks of
treatment, both doses of infliximab + MTX resulted in statistically
significantly greater response in signs and symptoms compared to MTX alone as
measured by the proportion of patients achieving ACR 20, 50 and 70 responses
(Table 7). More patients treated with infliximab reached a major clinical
response than placebo-treated patients (Table 7).
Table 7 : ACR response (percent of patients) for
infliximab
Response |
Study RA I |
Study RA II |
Placebo+ MTX
(n=88) |
Infliximab + MTX |
Placebo +MTX
(n=274) |
Infliximab + MTX |
3 mg/kg |
10 mg/kg |
3 mg/kgq 8 wks
(n=351) |
6 mg/kg q8 wks
(n=355) |
q8 wks
(n=86) |
q4 wks
(n=86) |
q8 wks
(n=87) |
q4 wks
(n=81) |
ACR 20 |
Week 30 |
20% |
50%a |
50% a |
52% a |
58% a |
N/A |
N/A |
N/A |
Week 54 |
17% |
42% a |
48% a |
59% a |
59% a |
54% |
62% c |
66% a |
ACR 50 |
Week 30 |
5% |
27% a |
29% a |
31% a |
26% a |
N/A |
N/A |
N/A |
Week 54 |
9% |
21% c |
34% a |
40% a |
38% a |
32% |
46% a |
50% a |
ACR 70 |
Week 30 |
0% |
8% b |
11% b |
18% a |
11% a |
N/A |
N/A |
N/A |
Week 54 |
2% |
11% c |
18% a |
26% a |
19% a |
21% |
33% b |
37% a |
Major clinical response# |
0% |
7% c |
8% b |
15% a |
6% c |
8% |
12% |
17% a |
# A major clinical response was
defined as a 70% ACR response for 6 consecutive months (consecutive visits
spanning at least 26 weeks) through Week 102 for Study RA I and Week 54 for
Study RA II.
a P ≤ 0.001
b P < 0.01
c P < 0.05 |
Table 8 Â : Components of ACR
20 at baseline and 54 weeks (Study RA I)
Parameter (medians) |
Placebo + MTX
(n=88) |
Infliximab + MTXa
(n=340) |
Baseline |
Week 54 |
Baseline |
Week 54 |
No. of Tender Joints |
24 |
16 |
32 |
8 |
No. of Swollen Joints |
19 |
13 |
20 |
7 |
Painb |
6.7 |
6.1 |
6.8 |
3.3 |
Physician’s Global Assessmentb |
6.5 |
5.2 |
6.2 |
2.1 |
Patient’s Global Assessmentb |
6.2 |
6.2 |
6.3 |
3.2 |
Disability Index (HAQ-DI)c |
1.8 |
1.5 |
1.8 |
1.3 |
CRP (mg/dL) |
3.0 |
2.3 |
2.4 |
0.6 |
a All doses/schedules of infliximab + MTX
b Visual Analog Scale (0=best, 10=worst)
c Health Assessment Questionnaire, measurement of 8 categories: dressing
and grooming, arising, eating, walking, hygiene, reach, grip, and activities
(0=best, 3=worst) |
Radiographic Response
Structural damage in both hands
and feet was assessed radiographically at Week 54 by the change from baseline
in the van der Heijde-modified Sharp (vdH-S) score, a composite score of
structural damage that measures the number and size of joint erosions and the
degree of joint space narrowing in hands/wrists and feet.3
In Study RA I, approximately
80% of patients had paired X-ray data at 54 weeks and approximately 70% at 102 weeks. The inhibition of
progression of structural damage was observed at 54 weeks (Table 9) and
maintained through 102 weeks.
In Study RA II, > 90% of
patients had at least 2 evaluable X-rays. Inhibition of progression of
structural damage was observed at Weeks 30 and 54 (Table 9) in infliximab + MTX
groups compared to MTX alone. Patients treated with infliximab + MTX
demonstrated less progression of structural damage compared to MTX alone,
whether baseline acute-phase reactants (ESR and CRP) were normal or elevated:
patients with elevated baseline acute-phase reactants treated with MTX alone
demonstrated a mean progression in vdH-S score of 4.2 units compared to
patients treated with infliximab + MTX who demonstrated 0.5 units of
progression; patients with normal baseline acute phase reactants treated with
MTX alone demonstrated a mean progression in vdH-S score of 1.8 units compared
to infliximab + MTX who demonstrated 0.2 units of progression. Of patients
receiving infliximab + MTX, 59% had no progression (vdH-S score ≤ 0 unit)
of structural damage compared to 45% of patients receiving MTX alone. In a
subset of patients who began the study without erosions, infliximab + MTX
maintained an erosion-free state at 1 year in a greater proportion of patients
than MTX alone, 79% (77/98) vs. 58% (23/40), respectively (P < 0.01). Fewer
patients in infliximab + MTX groups (47%) developed erosions in uninvolved
joints compared to MTX alone (59%).
Table 9 :Radiographic change
from baseline to Week 54
|
Study RA I |
Study RA II |
Placebo+ MTX
(n=64) |
Infliximab + MTX |
Placebo+ MTX
(n=282) |
Infliximab + MTX |
3 mg/kg q8wks
(n=71) |
10 mg/kg q8wks
(n=77) |
3 mg/kg q8wks
(n=359) |
6 mg/kg q8wks
(n=363) |
Total Score |
Baseline |
Mean |
79 |
78 |
65 |
11.3 |
11.6 |
11.2 |
Median |
55 |
57 |
56 |
5.1 |
5.2 |
5.3 |
Change from baseline |
Mean |
6.9 |
1.3a |
0.2a |
3.7 |
0.4a |
0.5a |
Median |
4.0 |
0.5 |
0.5 |
0.4 |
0.0 |
0.0 |
Erosion Score |
Baseline |
Mean |
44 |
44 |
33 |
8.3 |
8.8 |
8.3 |
Median |
25 |
29 |
22 |
3.0 |
3.8 |
3.8 |
Change from baseline |
4.1 |
0.2a |
0.2a |
3.0 |
0.3a |
0.1a |
Mean Median |
2.0 |
0.0 |
0.5 |
0.3 |
0.0 |
0.0 |
JSN Score |
Baseline |
|
|
|
|
|
|
Mean |
36 |
34 |
31 |
3.0 |
2.9 |
2.9 |
Median |
26 |
29 |
24 |
1.0 |
1.0 |
1.0 |
Change from baseline |
Mean |
2.9 |
1.1a |
0.0a |
0.6 |
0.1a |
0.2 |
Median |
1.5 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
a P < 0.001 for each outcome against placebo. |
Physical Function Response
Physical function and
disability were assessed using the Health Assessment Questionnaire (HAQ-DI) and
the general health-related quality of life questionnaire SF-36.
In Study RA I, all
doses/schedules of infliximab + MTX showed significantly greater improvement
from baseline in HAQ-DI and SF-36 physical component summary score averaged
over time through Week 54 compared to placebo + MTX, and no worsening in the
SF-36 mental component summary score. The median (interquartile range)
improvement from baseline to Week 54 in HAQ-DI was 0.1 (-0.1, 0.5) for the
placebo + MTX group and 0.4 (0.1, 0.9) for infliximab + MTX (p < 0.001). Both
HAQ-DI and SF-36 effects were maintained through Week 102. Approximately 80% of
patients in all doses/schedules of infliximab + MTX remained in the trial
through 102 weeks.
In Study RA II, both treatment
groups of infliximab showed greater improvement in HAQ-DI from baseline
averaged over time through Week 54 compared to MTX alone; 0.7 for infliximab + MTX
vs. 0.6 for MTX alone (P ≤ 0.001). No worsening in the SF-36 mental
component summary score was observed.
Ankylosing Spondylitis
The safety and efficacy of
infliximab were assessed in a randomized, multicenter, double-blind,
placebo-controlled study in 279 patients with active ankylosing spondylitis.
Patients were between 18 and 74 years of age, and had ankylosing spondylitis as
defined by the modified New York criteria for Ankylosing Spondylitis.4
Patients were to have had active disease as evidenced by both a Bath Ankylosing
Spondylitis Disease Activity Index (BASDAI) score > 4 (possible range 0-10)
and spinal pain > 4 (on a Visual Analog Scale [VAS] of 0-10). Patients with
complete ankylosis of the spine were excluded from study participation, and the
use of Disease Modifying of 56 Reference ID: 3912620
Anti-Rheumatic Drugs (DMARDs) and systemic
corticosteroids were prohibited. Doses of 5 mg/kg of infliximab or placebo were
administered intravenously at Weeks 0, 2, 6, 12 and 18.
At 24 weeks, improvement in the signs and symptoms of ankylosing
spondylitis, as measured by the proportion of patients achieving a 20%
improvement in ASAS response criteria (ASAS 20), was seen in 60% of patients in
infliximab group vs. 18% of patients in the placebo group (p < 0.001).
Improvement was observed at Week 2 and maintained through Week 24 (Figure 3 and
Table 10).
Figure 3 : Proportion of
patients achieving ASAS 20 response
At 24 weeks, the proportions of
patients achieving a 50% and a 70% improvement in the signs and symptoms of
ankylosing spondylitis, as measured by ASAS response criteria (ASAS 50 and ASAS
70, respectively), were 44% and 28%, respectively, for patients receiving
infliximab, compared to 9% and 4%, respectively, for patients receiving placebo
(P < 0.001, infliximab vs. placebo). A low level of disease activity (defined
as a value < 20 [on a scale of 0 -100 mm] in each of the 4 ASAS response
parameters) was achieved in 22% of patients treated with infliximab vs. 1% in
placebo-treated patients (P < 0.001).
Table 10 : Components of ankylosing spondylitis
disease activity
|
Placebo (n=78) |
Infliximab 5 mg/kg (n=201) |
Baseline |
24 Weeks |
Baseline |
24 Weeks |
P-value |
ASAS 20 response |
Criteria (Mean) |
Patient Global Assessmenta |
6.6 |
6.0 |
6.8 |
3.8 |
< 0.001 |
Spinal paina |
7.3 |
6.5 |
7.6 |
4.0 |
< 0.001 |
BASFIb |
5.8 |
5.6 |
5.7 |
3.6 |
< 0.001 |
Inflammationc |
6.9 |
5.8 |
6.9 |
3.4 |
< 0.001 |
Acute Phase Reactants |
Median CRPd (mg/dL) |
1.7 |
1.5 |
1.5 |
0.4 |
< 0.001 |
Spinal Mobility (cm, Mean) |
Modified Schober’s teste |
4.0 |
5.0 |
4.3 |
4.4 |
0.75 |
Chest expansione |
3.6 |
3.7 |
3.3 |
3.9 |
0.04 |
Tragus to walle |
17.3 |
17.4 |
16.9 |
15.7 |
0.02 |
Lateral spinal flexione |
10.6 |
11.0 |
11.4 |
12.9 |
0.03 |
a Measured on a VAS with 0=“none” and
10=“severe”
b Bath Ankylosing Spondylitis Functional Index (BASFI), average of
10 questions
c Inflammation, average of last 2 questions on the 6-question BASDAI
d CRP normal range 0–1.0 mg/dL
e Spinal mobility normal values: modified Schober's test: > 4 cm;
chest expansion: > 6 cm; tragus to wall: < 15 cm; Â lateral spinal flexion:
> 10 cm |
The median improvement from
baseline in the general health-related quality-of-life questionnaire SF-36 physical
component summary score at Week 24 was 10.2 for infliximab group vs. 0.8 for
the placebo group (P < 0.001). There was no change in the SF-36 mental
component summary score in either infliximab group or the placebo group.
Results of this study were similar
to those seen in a multicenter double-blind, placebo-controlled study of 70
patients with ankylosing spondylitis.
Psoriatic Arthritis
Safety and efficacy of
infliximab were assessed in a multicenter, double-blind, placebo-controlled
study in 200 adult patients with active psoriatic arthritis despite DMARD or
NSAID therapy ( ≥ 5 swollen joints and ≥ 5 tender joints) with 1 or
more of the following subtypes: arthritis involving DIP joints (n=49),
arthritis mutilans (n=3), asymmetric peripheral arthritis (n=40), polyarticular
arthritis (n=100), and spondylitis with peripheral arthritis (n=8). Patients also
had plaque psoriasis with a qualifying target lesion ≥ 2 cm in diameter.
Forty-six percent of patients continued on stable doses of methotrexate
( ≤ 25 mg/week). During the 24-week double-blind phase, patients received
either 5 mg/kg infliximab or placebo at Weeks 0, 2, 6, 14, and 22 (100 patients
in each group). At Week 16, placebo patients with < 10% improvement from baseline
in both swollen and tender joint counts were switched to infliximab induction
(early escape). At Week 24, all placebo-treated patients crossed over to
infliximab induction. Dosing continued for all patients through Week 46.
Clinical response
Treatment with infliximab resulted in improvement in
signs and symptoms, as assessed by the ACR criteria, with 58% of patients
treated with infliximab achieving ACR 20 at Week 14, compared with 11% of
placebo-treated patients (P < 0.001). The response was similar regardless of
concomitant use of methotrexate. Improvement was observed as early as Week 2.
At 6 months, the ACR 20/50/70 responses were achieved by 54%, 41%, and 27%,
respectively, of patients receiving infliximab compared to 16%, 4%, and 2%,
respectively, of patients receiving placebo. Similar responses were seen in
patients with each of the subtypes of psoriatic arthritis, although few
patients were enrolled with the arthritis mutilans and spondylitis with
peripheral arthritis subtypes.
Compared to placebo, treatment with infliximab resulted
in improvements in the components of the ACR response criteria, as well as in
dactylitis and enthesopathy (Table 11). The clinical response was maintained
through Week 54. Similar ACR responses were observed in an earlier randomized,
placebo-controlled study of 104 psoriatic arthritis patients, and the responses
were maintained through 98 weeks in an open-label extension phase.
Table 11 : Components of ACR 20 and percentage of
patients with 1 or more joints with dactylitis and percentage of patients with
enthesopathy at baseline and Week 24
Patients Randomized |
Placebo
(n=100) |
Infliximab 5mg/kga
(n=100) |
Baseline |
Week 24 |
Baseline |
Week 24 |
Parameter (medians) |
24 |
20 |
20 |
6 |
No. of Tender Jointsb |
12 |
9 |
12 |
3 |
No. of Swollen Jointsc |
6.4 |
5.6 |
5.9 |
2.6 |
Paind |
6.0 |
4.5 |
5.6 |
1.5 |
Physician’s Global Assessmentd |
6.1 |
5.0 |
5.9 |
2.5 |
Disability Index (HAQ-DI)e |
1.1 |
1.1 |
1.1 |
0.5 |
CRP (mg/dL)f |
1.2 |
0.9 |
1.0 |
0.4 |
% Patients with 1 or more digits with dactylitis |
41 |
33 |
40 |
15 |
% Patients with enthesopathy |
35 |
36 |
42 |
22 |
a P < 0.001 for percent change from baseline in all
components of ACR 20 at Week 24, P < 0.05 for % of patients with dactylitis,
and P=0.004 for % of patients with enthesopathy at Week 24
b Scale 0-68
c Scale 0-66
d Visual Analog Scale (0=best, 10=worst)
e Health Assessment Questionnaire, measurement of 8 categories:
dressing and grooming, arising, eating, walking, hygiene, reach, grip, and
activities (0=best, 3=worst)
f Normal range 0-0.6 mg/dL |
Improvement in Psoriasis Area
and Severity Index (PASI) in psoriatic arthritis patients with baseline body
surface area (BSA) ≥ 3% (n=87 placebo, n=83 infliximab) was achieved at
Week 14, regardless of concomitant methotrexate use, with 64% of patients
treated with infliximab achieving at least 75% improvement from baseline vs. 2%
of placebo-treated patients; improvement was observed in some patients as early
as Week 2. At 6 months, the PASI 75 and PASI 90 responses were achieved by 60%
and 39%, respectively, of patients receiving infliximab compared to 1% and 0%,
respectively, of patients receiving placebo. The PASI response was generally
maintained through Week 54. [See also Clinical Studies].
Radiographic Response
Structural damage in both hands
and feet was assessed radiographically by the change from baseline in the van
der Heijde-Sharp (vdH-S) score, modified by the addition of hand DIP joints.
The total modified vdH-S score is a composite score of structural damage that
measures the number and size of joint erosions and the degree of joint space
narrowing (JSN) in the hands and feet. At Week 24, patients treated with
infliximab had less radiographic progression than placebo-treated patients
(mean change of -0.70 vs. 0.82, P < 0.001). Patients treated with infliximab
also had less progression in their erosion scores (-0.56 vs 0.51) and JSN
scores (-0.14 vs 0.31). The patients in infliximab group demonstrated continued
inhibition of structural damage at Week 54. Most patients showed little or no
change in the vdH-S score during this 12month study (median change of 0 in both
patients who initially received infliximab or placebo). More patients in the
placebo group (12%) had readily apparent radiographic progression compared with
infliximab group (3%).
Physical Function
Physical function status was assessed using the HAQ
Disability Index (HAQ-DI) and the SF-36 Health Survey. Patients treated with
infliximab demonstrated significant improvement in physical function as
assessed by HAQ-DI (median percent improvement in HAQ-DI score from baseline to
Week 14 and 24 of 43% for infliximab-treated patients vs 0% for placebo-treated
patients).
During the placebo-controlled portion of the trial (24
weeks), 54% of patients treated with infliximab achieved a clinically
meaningful improvement in HAQ-DI ( ≥ 0.3 unit decrease) compared to 22% of
placebo-treated patients. Patients treated with infliximab also demonstrated
greater improvement in the SF-36 physical and mental component summary scores than
placebo-treated patients. The responses were maintained for up to 2 years in an
open-label extension study.
Plaque Psoriasis
The safety and efficacy of infliximab were assessed in 3
randomized, double-blind, placebo-controlled studies in patients 18 years of
age and older with chronic, stable plaque psoriasis involving ≥ 10% BSA, a
minimum PASI score of 12, and who were candidates for systemic therapy or
phototherapy. Patients with guttate, pustular, or erythrodermic psoriasis were
excluded from these studies. No concomitant anti-psoriatic therapies were
allowed during the study, with the exception of low-potency topical
corticosteroids on the face and groin after Week 10 of study initiation.
Study I (EXPRESS) evaluated 378 patients who received
placebo or infliximab at a dose of 5 mg/kg at Weeks 0, 2, and 6 (induction
therapy), followed by maintenance therapy every 8 weeks. At Week 24, the
placebo group crossed over to infliximab induction therapy (5 mg/kg), followed
by maintenance therapy every 8 weeks. Patients originally randomized to
infliximab continued to receive infliximab 5 mg/kg every 8 weeks through Week
46. Across all treatment groups, the median baseline PASI score was 21 and the
baseline Static Physician Global Assessment (sPGA) score ranged from moderate
(52% of patients) to marked (36%) to severe (2%). In addition, 75% of patients
had a BSA > 20%. Seventy-one percent of patients previously received systemic
therapy, and 82% received phototherapy.
Study II (EXPRESS II) evaluated 835 patients who received
placebo or infliximab at doses of 3 mg/kg or 5 mg/kg at Weeks 0, 2, and 6
(induction therapy). At Week 14, within each dose group, patients were
randomized to either scheduled (every 8 weeks) or as needed (PRN) maintenance
treatment through Week 46. At Week 16, the placebo group crossed over to
infliximab induction therapy (5 mg/kg), followed by maintenance therapy every 8
weeks. Across all treatment groups, the median baseline PASI score was 18, and
63% of patients had a BSA > 20%. Fifty-five percent of patients previously
received systemic therapy, and 64% received a phototherapy.
Study III (SPIRIT) evaluated 249 patients who had
previously received either psoralen plus ultraviolet A treatment (PUVA) or
other systemic therapy for their psoriasis. These patients were randomized to
receive either placebo or infliximab at doses of 3 mg/kg or 5 mg/kg at Weeks 0,
2, and 6. At Week 26, patients with a sPGA score of moderate or worse (greater than
or equal to 3 on a scale of 0 to 5) received an additional dose of the
randomized treatment. Across all treatment groups, the median baseline PASI
score was 19, and the baseline sPGA score ranged from moderate (62% of
patients) to marked (22%) to severe (3%). In addition, 75% of patients had a
BSA > 20%. Of the enrolled patients, 114 (46%) received the Week 26
additional dose.
In Studies I, II and III, the primary endpoint was the
proportion of patients who achieved a reduction in score of at least 75% from
baseline at Week 10 by the PASI (PASI 75). In Study I and Study III, another
evaluated outcome included the proportion of patients who achieved a score of
“cleared” or “minimal” by the sPGA. The sPGA is a 6-category scale ranging from
“5 = severe” to “0 = cleared” indicating the physician's overall assessment of
the psoriasis severity focusing on induration, erythema, and scaling. Treatment
success, defined as “cleared” 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.
Study II also evaluated the proportion of patients who
achieved a score of “clear” or “excellent” by the relative Physician's Global
Assessment (rPGA). The rPGA is a 6-category scale ranging from “6 = worse” to
“1 = clear” that was assessed relative to baseline. Overall lesions were graded
with consideration to the percent of body involvement as well as overall
induration, scaling, and erythema. Treatment success, defined as “clear” or
“excellent,” consisted of some residual pinkness or pigmentation to marked
improvement (nearly normal skin texture; some erythema may be present). The
results of these studies are presented in Table 12.
Table 12 : Psoriasis studies I, II, and III, Week 10
percentage of patients who achieved PASI75 and percentage who achieved
treatment “success” with Physician's Global Assessment
|
Placebo |
Infliximab |
3 mg/kg |
1 5 mg/kg |
Psoriasis Study I - patients randomizeda |
77 |
--- |
301 |
PASI 75 |
2 (3%) |
--- |
242 (80%)* |
sPGA |
3 (4%) |
--- |
242 (80%)* |
Psoriasis Study II - patients randomizeda |
208 |
313 |
314 |
PASI 75 |
4 (2%) |
220 (70%)* |
237 (75%)* |
rPGA |
2 (1%) |
217 (69%)* |
234 (75%)* |
Psoriasis Study IIII - patients randomizedb |
51 |
99 |
99 |
PASI 75 |
3 (6%) |
71 (72%)* |
87 (88%)* |
sPGA |
5 (10%) |
71 (72%)* |
89 (90%)* |
* P < 0.001 compared with
placebo
a Patients with missing data at Week 10 were considered as
nonresponders.
b Patients with missing data at Week 10 were imputed by last
observation. |
In Study I, in the subgroup of
patients with more extensive psoriasis who had previously received
phototherapy, 85% of patients on 5 mg/kg infliximab achieved a PASI 75 at Week
10 compared with 4% of patients on placebo.
In Study II, in the subgroup of
patients with more extensive psoriasis who had previously received
phototherapy, 72% and 77% of patients on 3 mg/kg and 5 mg/kg infliximab
achieved a PASI 75 at Week 10 respectively compared with 1% on placebo. In
Study II, among patients with more extensive psoriasis who had failed or were
intolerant to phototherapy, 70% and 78% of patients on 3 mg/kg and 5 mg/kg
infliximab achieved a PASI 75 at Week 10 respectively, compared with 2% on
placebo.
Maintenance of response was
studied in a subset of 292 and 297 patients treated with infliximab in the 3
mg/kg and 5 mg/kg groups; respectively, in Study II. Stratified by PASI
response at Week 10 and investigational site, patients in the active treatment
groups were re-randomized to either a scheduled or as needed maintenance (PRN)
therapy, beginning on Week 14.
The groups that received a
maintenance dose every 8 weeks appear to have a greater percentage of patients
maintaining a PASI 75 through week 50 as compared to patients who received the
as needed or PRN doses, and the best response was maintained with the 5
mg/kg every 8-week dose. These results are shown in Figure 4. At Week 46, when
infliximab serum concentrations were at trough level, in the every 8-week dose
group, 54% of patients in the 5 mg/kg group compared to 36% in the 3 mg/kg
group achieved PASI 75. The lower percentage of PASI 75 responders in the 3
mg/kg every 8-week dose group compared to the 5 mg/kg group was associated with
a lower percentage of patients with detectable trough serum infliximab levels.
This may be related in part to higher antibody rates [see
ADVERSE REACTIONS]. In addition, in a subset of patients who had
achieved a response at Week 10, maintenance of response appears to be greater
in patients who received infliximab every 8 weeks at the 5 mg/kg dose.
Regardless of whether the maintenance doses are PRN or every 8 weeks, there is
a decline in response in a subpopulation of patients in each group over time.
The results of Study I through Week 50 in the 5 mg/kg every 8 weeks maintenance
dose group were similar to the results from Study II.
Figure 4 : Proportion of
patients achieving ≥ 75% improvement in PASI from baseline through Week
50; patients randomized at Week 14
Efficacy and safety of
infliximab treatment beyond 50 weeks have not been evaluated in patients with
plaque psoriasis.
REFERENCES
3. van der Heijde DM, van Leeuwen MA, van Riel PL, et al.
Biannual radiographic assessments of hands and feet in a three-year prospective
follow-up of patients with early rheumatoid arthritis. Arthritis Rheum. 1992;35(1):26-34.
4. van der Linden S, Valkenburg HA, Cats A. Evaluation of
diagnostic criteria for ankylosing spondylitis. A proposal for modification of
the New York criteria. Arthritis Rheum. 1984;27(4):361-368.
5. Schroeder KW, Tremaine WJ, Ilstrup DM. Coated oral
5-aminosalicylic acid therapy for mildly to moderately active ulcerative
colitis. A randomized study. N Engl J Med. 1987;317(26):1625-1629.