Background/Purpose:

Biologics constitute an important drug category in the pharmacological treatment of rheumatoid arthritis (RA). Drug-free remission (REM) may also be achievable if the condition is responsive to treatment. In RA patients who had been treated with tocilizumab (TCZ) and whose disease activity was well-controlled, the administration interval of TCZ was extended, and a follow-up observation was carried out.

Methods:

The study was conducted on 101 RA patients treated with TCZ, who could be followed up for 52 weeks or longer. The cases were analyzed by dividing into two groups: a group of 41 patients whose administration interval was extended after achievement of a state of low disease activity (LDA) (extended-interval administration group, E-group), and a group of 61 patients for whom the doses continued to be administered at 4-week intervals in accordance with the package insert (standard-administration group, S-group). Evaluation of disease activity was conducted by using DAS28-ESR.

Results:

Comparison between S-group and E-group showed significant differences (p<0.05) in the following background items at the time of introduction of TCZ therapy: swollen joint count (SJC): 18.7±7.6 and 15.6±8.4, CRP (mg/dl): 2.77±3.01 and 1.81±2.56, DAS28-CRP: 6.1±1.5 and 5.6±1.4, CDAI: 51.7±16.6 and 43.6±17.5, and SDAI: 50.0±18.4 and 49.8±18.5. In E-group, extension of the interval was attempted at an average of 31.6 weeks (11 weeks to 101 weeks) after initiation of the introduction of TCZ therapy. In average, the duration of persistence of LDA until initiation of the extension of administration intervals was 23.1 weeks (4 weeks to 78 weeks). The changes in DAS28-ESR scores were examined after initiation of the extension of the administration interval; and the findings showed that the scores were 2.00±0.93 at the time of the initiation of the extension, 2.02±0.92 at 12 weeks, 2.11±1.13 at 24 weeks, 2.16±1.00 at 36 weeks, and 2.06±1.00 at 52 weeks. The REM rate was 70.7% at the time of the initiation of the extension, 65.9% at 24 weeks, and 61.0% at 52 weeks. In 7 patients (17.1%), relapse developed within 52 weeks following the extension of the administration interval of TCZ, and in all cases, resetting the administration interval back to 4 weeks led to an improvement of the patients’ condition and an achievement of LDA within 24 weeks. The patients who relapsed showed significant differences in terms of the duration of the persistence of LDA until initiation of the extension, as well as in terms of ESR and DAS28-ESR scores at the time of the initiation of the extension (p<0.05). Based on the ROC curve, the DAS28-ESR at the time of initiation of the extension of the administration interval showed an AUC of 0.732 with a cut-off value of 1.81 weeks; and the duration of the persistence of LDA until initiation of the extension of the administration interval showed an AUC of 0.735 with a cut-off value of 14.0 weeks.

Conclusion:

Extension of administration intervals was carried out in 40% of RA patients treated with TCZ. For 82.9% of the cases, disease activity was maintained at a good level for a period of 52 weeks or longer.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/possibility-of-extension-of-the-administration-interval-of-tocilizumab-in-the-treatment-of-rheumatoid-arthritis/