Sustainable Efficacy of Switching From Intravenous to Subcutaneous Tocilizumab Monotherapy in Patients With Rheumatoid Arthritis

Abstract

Objective: To evaluate the efficacy and safety of switching from intravenous (IV) tocilizumab (TCZ) to subcutaneous (SC) TCZ monotherapy in rheumatoid arthritis patients.

Methods: Patients who had completed 24 weeks of TCZ-SC (162 mg/2 weeks) or TCZ-IV (8 mg/kg/4 weeks) monotherapy in the double-blind period of the MUSASHI study were enrolled in an 84-week open-label extension period. All received TCZ-SC (162 mg/2 weeks) monotherapy. Effects of the IV to SC switch were evaluated at week 36 (12 weeks after switching).

Results: Overall, 319 patients received ≥1 dose of TCZ-SC during the open-label extension period; 160 switched from TCZ-IV to TCZ-SC (TCZ IV/SC) and 159 continued TCZ-SC (TCZ SC/SC). Disease Activity Score in 28 joints using the erythrocyte sedimentation rate clinical remission rates were 62.5% (100 of 160) for TCZ IV/SC and 50.0% (79 of 158) for TCZ SC/SC at week 24, and were maintained at 62.5% (100 of 160) and 57.0% (90 of 158), respectively, at week 36. In the TCZ IV/SC group, 9% of patients (9 of 100) who had achieved remission at week 24 could not maintain remission at week 36. In TCZ IV/SC patients weighing ≥70 kg, the percentage with a sufficient serum TCZ concentration (≥1 μg/ml) decreased from 90.9% (10 of 11) at week 24 to 45.5% (5 of 11) at week 36. Overall safety profiles were similar in TCZ IV/SC and TCZ SC/SC except for mild injection site reactions in TCZ IV/SC.

Conclusion: Efficacy is adequately maintained in most patients switching from TCZ-IV (8 mg/kg/4 weeks) to TCZ-SC (162 mg/2 weeks) monotherapy. Patients receiving TCZ-IV can switch to TCZ-SC without serious safety concerns. Clinical efficacy may be reduced after switching in some patients with high body weight.

Figure 1

Time course of disease activity scores. A, Disease Activity Score in 28 joints using the erythrocyte sedimentation rate (DAS28‐ESR), B, Clinical Disease Activity Index (CDAI) score, and C, American College of Rheumatology 20%/50%/70% improvement criteria (ACR20/50/70) response. TCZ = tocilizumab; IV = intravenous; SC = subcutaneous.

Figure 2

Efficacy evaluation by disease activity category in patients who switched from intravenous to subcutaneous tocilizumab (TCZ IV/SC) and who continued TCZ‐SC. A, Disease Activity Score in 28 joints using the erythrocyte sedimentation rate (DAS28‐ESR), and B, Clinical Disease Activity Index (CDAI) score.

Figure 3

Changes in disease activity category by Disease Activity Score in 28 joints using the erythrocyte sedimentation rate in patients who switched from intravenous to subcutaneous tocilizumab (TCZ IV/SC) and who continued TCZ‐SC. A, Disease activity at week 36 in patients who achieved remission at week 24, B, Disease activity at week 36 in patients who achieved low disease activity at week 24, and C, Disease activity at week 36 in patients who achieved medium or high disease activity at week 24. The values in the columns indicate the number of patients.

Figure 4

A, Changes in Disease Activity Score in 28 joints using the erythrocyte sedimentation rate (DAS28‐ESR) remission rate were stratified by 10 kg of body weight in patients who switched from intravenous to subcutaneous tocilizumab (TCZ IV/SC) and who continued TCZ‐SC. B, Percentage of patients with serum trough TCZ concentration of ≥1 μg/ml was stratified by 10 kg of body weight. The values below each column indicate the number of total patients in each weight category. The bars show the 95% confidence interval.