Readministration of infliximab was generally safe and effective in patients with ankylosing spondylitis who had previously discontinued treatment, reported Dr. Xenofon Baraliakos and colleagues.
Dr. Baraliakos, of Rheumazentrum Ruhrgebiet in Herne, Germany, and colleagues designed a study to evaluate the safety and efficacy of infliximab readministration in patients with ankylosing spondylitis who experienced clinical relapse following infliximab withdrawal (J. Rheumatol. 2007 Feb. 1; [Epub ahead of print]). The study population consisted of 42 patients with ankylosing spondylitis who had completed a 3-year, open-label extension study of continuous infliximab therapy administered by infusion at a dose of 5 mg/kg every 6 weeks.
Patients discontinued infliximab at the end of the third year of the open-label extension study. The date of infliximab withdrawal was defined as timepoint (TP) 1. Patients were assessed every 6 weeks after infliximab withdrawal for signs of disease flare, the investigators reported. Clinical relapse was defined by a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score of 4 or greater and a physician's global assessment score of 4 or greater. Patients who experienced clinical relapse were reinfused with infliximab at a dose of 5 mg/kg. The time of clinical relapse was defined as TP2.
Patients were reinfused every 6 weeks after TP2 for the duration of the study. Clinical data were obtained at each visit throughout the study. Study-specific data were collected at the time of infliximab withdrawal, at the time of clinical relapse, and at 24 and 48 weeks after TP2.
Of the 42 patients who enrolled in the study, one remained in clinical remission 48 weeks after infliximab withdrawal, the investigators noted. The remaining 41 patients experienced clinical relapse and were reinfused. One patient, who received eight infusions, dropped out of the study because of repeated local infections.
Infliximab treatment can induce antibodies to infliximab, resulting in the possible loss of clinical efficacy, they noted. Due to measurement difficulties, antibody assays were regarded as inconclusive in patients who had detectable serum levels of infliximab. Of the 42 patients, 27 (64.3%) provided blood samples at the time of infliximab withdrawal, and 35 (83.3%) provided blood samples at clinical relapse. High serum levels of infliximab were detected in 24 (88.9%) of the 27 patients who provided blood samples at infliximab withdrawal, while high levels were detected in 18 patients (51.4%) who provided blood samples at clinical relapse.
One patient showed antibodies to infliximab at 6 weeks after withdrawal, despite an initial favorable response during the previous 3-year study, and no clinical relapse until 24 weeks. This patient withdrew from the study after eight infusions because of repeated local infections.
Among the patients who completed the study after infliximab readministration, mean BASDAI scores increased from 2.5 at the time of infliximab withdrawal to 6.0 at the time of clinical relapse. Mean BASDAI scores decreased following infliximab readministration, to mean values of 2.7 at week 24 to 2.6 at week 48. Median C-reactive protein levels increased from 1.0 at infliximab withdrawal to 11.2 at clinical relapse, dropping again after infliximab readministration to 1.6 at week 24 and 1.8 at week 48. Erythrocyte sedimentation rate showed a similar pattern, rising from median levels of 8 at infliximab withdrawal, to 24 at clinical relapse, and decreasing to 6 and 11 at weeks 24 and 48, respectively.
The authors acknowledged receiving research support from Centocor, the manufacturer of Remicade (infliximab).
Infliximab readministration after relapse lowered BASDAI scores, CRP levels, and ESRs. DR. BARALIAKOS