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
pro-inflammatory cytokines such as interleukins (IL) 1 and 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, allow 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 patients treated with infliximab
products 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 product 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
(IV) 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 8-week 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 or
ulcerative colitis following the administration of 5 mg/kg infliximab.
Population pharmacokinetic analysis showed that in
children with juvenile rheumatoid arthritis (JRA) with a body weight of up to
35 kg receiving 6 mg/kg infliximab and children with JRA with body weight
greater than 35 kg up to adult body weight receiving 3 mg/kg infliximab, 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 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
response 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 infliximab maintenance groups 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 q8 wks |
5 mg/kg |
10 mg/kg |
Week 30 |
25/102 |
41/104 |
48/105 |
Clinical remission |
25% |
39% |
46% |
P-valuec |
|
0.022 |
0.001 |
Week 54 |
6/54 |
14/56 |
18/53 |
Patients in remission able to 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 the 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
infliximab-treated groups 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 SF-36.
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 the infliximab maintenance group had endoscopic
evidence of mucosal healing compared to 1 of 28 patients in the placebo group
at Week 10. Of the infliximab-treated patients 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 infliximab
maintenance patients 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-mercaptopurine (6-MP)
and/or azathioprine (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
infliximab-treated patients was 2 and 12 weeks, respectively. Closure of all
fistulas was achieved in 52% of infliximab-treated patients 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
infliximab at Weeks 0, 2 and 6. Patients were randomized to placebo or 5 mg/kg
infliximab maintenance 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 infliximab maintenance had a longer time to
loss of fistula response compared to the placebo maintenance group (Figure 2).
At Week 54, 38% (33/87) of infliximab-treated patients had no draining fistulas
compared with 22% (20/90) of placebo-treated patients (P=0.02). Compared to
placebo maintenance, patients on infliximab maintenance 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 infliximab
maintenance therapy 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 infliximab maintenance
patients 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
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 12-week 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 |
Every 12-Week |
Treatment Group |
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 the infliximab treatment groups 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 I |
|
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 Weeks 8 and 30) |
23% |
49%* |
46%* |
15% |
41%* |
53%* |
(Clinical response at Weeks 8, 30, and 54) |
14% |
39%* |
37%* |
NA |
NA |
NA |
Patients randomized |
121 |
121 |
122 |
123 |
121 |
120 |
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 Weeks 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 UC 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% |
Pediatric Ulcerative Colitis
The safety and effectiveness of
infliximab products for reducing signs and symptoms and inducing and
maintaining clinical remission in pediatric patients aged 6 years and older
with moderately to severely active ulcerative colitis who have had an
inadequate response to conventional therapy are supported by evidence from
adequate and well-controlled studies of infliximab in adults. Additional safety
and pharmacokinetic data were collected in an open-label pediatric UC trial in
60 pediatric patients aged 6 through 17 years (median age 14.5 years) with
moderately to severely active ulcerative colitis (Mayo score of 6 to 12; Endoscopic
subscore ≥2) and an inadequate response to conventional therapies. At
baseline, the median Mayo score was 8, 53% of patients were receiving
immunomodulator therapy (6-MP/AZA/MTX), and 62% of patients were receiving
corticosteroids (median dose 0.5 mg/kg/day in prednisone equivalents).
Discontinuation of immunomodulators and corticosteroid taper were permitted
after Week 0.
All patients received induction
dosing of 5 mg/kg infliximab at Weeks 0, 2, and 6. Patients who did not respond
to infliximab at Week 8 received no further infliximab treatment and returned
for safety follow-up. At Week 8, 45 patients were randomized to a maintenance
regimen of 5 mg/kg infliximab given either every 8 weeks through Week 46 or
every 12 weeks through Week 42. Patients were allowed to change to a higher
dose and/or more frequent administration schedule if they experienced loss of
response.
Clinical response at Week 8 was
defined as a decrease from baseline in the Mayo score by ≥30% and
≥3 points, including a decrease in the rectal bleeding subscore by
≥1 points or achievement of a rectal bleeding subscore of 0 or 1.
Clinical remission at Week 8 was measured by the Mayo
score, defined as a Mayo score of ≤2 points with no individual subscore
>1. Clinical remission was also assessed at Week 8 and Week 54 using the
Pediatric Ulcerative Colitis Activity Index (PUCAI) 6 score and was defined by
a PUCAI score of <10 points. Endoscopies were performed at baseline and at
Week 8. A Mayo endoscopy subscore of 0 indicated normal or inactive disease and
a subscore of 1 indicated mild disease (erythema, decreased vascular pattern,
or mild friability). Of the 60 patients treated, 44 were in clinical response
at Week 8. Of 32 patients taking concomitant immunomodulators at baseline, 23
achieved clinical response at Week 8, compared to 21 of 28 of those not taking
concomitant immunomodulators at baseline. At Week 8, 24 of 60 patients were in
clinical remission as measured by the Mayo score and 17 of 51 patients were in
remission as measured by the PUCAI score.
At Week 54, 8 of 21 patients in the every 8-week
maintenance group and 4 of 22 patients in the every 12-week maintenance group
achieved remission as measured by the PUCAI score.
During maintenance phase, 23 of 45 randomized patients (9
in the every 8-week group and 14 in the every 12-week group) required an
increase in their dose and/or increase in frequency of infliximab
administration due to loss of response. Nine of the 23 patients who required a
change in dose had achieved remission at Week 54. Seven of those patients
received the 10 mg/kg every 8-week dosing.
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 infliximab + MTX: 3 mg/kg or 10 mg/kg of infliximab by
IV 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 naive 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 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)
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/kgq 8 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 responsed |
0% |
7%c |
8%b |
15%a |
6%c |
8% |
12% |
17%a |
a P≤0.001
b P<0.01
c P<0.05
d 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. |
Table 8: Components of ACR
20 at baseline and 54 weeks (Study RA I)
Parameter (medians) |
Placebo + MTX |
Infliximab + MTXa |
(n=88) |
(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 the 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 the 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 |
|
Infliximab + MTX |
Placebo + MTX
(n=282) |
Infliximab + MTX |
3 mg/kg q 8 wks
(n=71) |
10 mg/kg q8 wks
(n=77) |
3 mg/kg q8 wks
(n=359) |
6 mg/kg q8 wks
(n=363) |
Placebo + MTX
(n=64) |
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 |
Mean |
4.1 |
0.2a |
0.2a |
3.0 |
0.3a |
0.1a |
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 infliximab
treatment groups 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
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 the infliximab-treated 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 infliximab-treated patients 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) |
P-value |
Baseline |
24 Weeks |
Baseline |
24 Weeks |
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; 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 the 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 the 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 infliximab-treated patients 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 5 mg/kga
(n=100) |
Baseline |
Week 24 |
Baseline |
Week 24 |
Parameter (medians) |
No. of Tender Jointsb |
24 |
20 |
20 |
6 |
No. of Swollen Jointsc |
12 |
9 |
12 |
3 |
Paind |
6.4 |
5.6 |
5.9 |
2.6 |
Physician's Global Assessmentd |
6.0 |
4.5 |
5.6 |
1.5 |
Patient'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 infliximab-treated patients 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 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, infliximab-treated patients
had less radiographic progression than placebo-treated patients (mean
change of -0.70 vs. 0.82, P<0.001). infliximab-treated patients also
had less progression in their erosion scores (-0.56 vs 0.51) and JSN
scores (-0.14 vs 0.31). The patients in the 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 12-month 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 the infliximab group (3%).
Physical Function
Physical function status was assessed using the HAQ
Disability Index (HAQ-DI) and the SF-36 Health Survey. Infliximab-treated
patients 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 infliximab-treated patients achieved a clinically meaningful
improvement in HAQ-DI (≥0.3 unit decrease) compared to 22% of
placebo-treated patients. Infliximab-treated patients 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 infliximab 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 PASI 75 and percentage who achieved
treatment “success” with Physician's Global Assessment
|
Placebo |
Infliximab |
3 mg/kg |
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 III - 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 infliximab-treated patients 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.
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