ular psoriatic arthritis. During the 16-week double-blind phase, patients received either 5 mg/kg infliximab or placebo at weeks 0, 2, 6, and 14 (52 patients in each group). Starting at week 16, placebo patients were switched to infliximab and all patients subsequently received 5 mg/kg infliximab every 8 weeks up to week 46. After the first year of the study, 78 patients continued into an open-label extension to week 98.
In the second clinical study (IMPACT 2), efficacy and safety of infliximab were studied in 200 patients with active psoriatic arthritis ( 5 swollen joints and 5 tender joints). 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, 47 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.
Key efficacy results for IMPACT and IMPACT 2 are shown in Table 9 below:
Table 9: Effects on ACR and PASI in IMPACT and IMPACT 2
IMPACT
IMPACT 2*
Placebo
(Week 16)
Infliximab
(Week 16)
Infliximab
(Week 98)
Placebo
(Week 24)
Infliximab
(Week 24)
Infliximab
(Week 54)
Patients randomized
52
52
N/Aa
100
100
100
ACR response
(% of patients)
N
52
52
78
100
100
100
ACR 20 response*
5(10%)
34 (65%)
48 (62%)
16 (16%)
54 (54%)
53 (53%)
ACR 50 response*
0(0%)
24 (46%)
35 (45%)
4 (4%)
41(41%)
33 (33%)
ACR 70 response*
0(0%)
15 (29%)
27 (35%)
2 (2%)
27 (27%)
20 (20%)
PASI response
(% of patients)b
N
87
83
82
PASI 75 response**
1 (1%)
50 (60%)
40 (48.8%)
* ITT-analysis where subjects with missing data were included as non-responders
a Week 98 data for IMPACT includes combined placebo crossover and infliximab patients who entered the open-label extension
b Based on patients with PASI >2.5 at baseline for IMPACT, and patients with >3% BSA psoriasis skin involvement at baseline in IMPACT 2
** PASI 75 response for IMPACT not included due to low N; p<0.001 for infliximab vs. placebo at week 24 for IMPACT 2
In IMPACT and IMPACT 2, clinical responses were observed as early as week 2 and were maintained through week 98 and week 54 respectively. Efficacy has been demonstrated with or without concomitant use of methotrexate. Decreases in parameters of peripheral activity characteristic of psoriatic arthritis (such as number of swollen joints, number of painful/tender joints, dactylitis and presence of enthesopathy) were seen in the infliximab-treated patients.
Radiographic changes were assessed in IMPACT 2. Radiographs of hands and feet were collected at baseline, weeks 24 and 54. |
