Infliximab plus methotrexate (MTX) is approved for the treatment of rheumatoid arthritis (RA). Based on the benefit/risk profile of this combination therapy, lower doses of MTX would be preferable when infliximab efficacy can be maintained. We evaluated the ability of patients receiving infliximab plus MTX to achieve and maintain a clinical response while the dose of MTX was tapered.
Infliximab infusions were administered at a minimum dosage of 3 mg/kg at 8-week intervals (following three loading doses at weeks 0, 2, and 6) to patients who had an inadequate response to MTX. MTX tapering was initiated at week 22 or later when at least a 40% improvement in the combined tender and swollen joint count was achieved; dosages were reduced by 5 mg every 8 weeks to a protocol-specified minimum dosage of 5 mg per week. If the required dosage of MTX after a flare was greater than the baseline dosage, the patient was considered a treatment failure.
Of the 210 patients enrolled, 159 (76%) achieved a 40% or better improvement in the combined tender and swollen joint count and had their MTX doses tapered. In these 159 responders, the median (mean) dose of MTX was reduced from 15 (16.5) mg per week at baseline to 5 (7.1) mg per week at week 54. From the time of initial response, 79% of these patients had a zero- or a one-vial increase in infliximab, corresponding to an approximate dose increase of 1 mg/kg, through week 54.
Approximately 75% of the patients participating in this trial achieved at least a 40% reduction in the combined swollen and tender joint count (correlating with an American College of Rheumatology 20% [ACR20] response in 83% of patients) while reducing the mean MTX dose by 57%.