IV to Subcutaneous Switch OK for Tocilizumab

April 14, 2015

More good news for Actemra: rheumatoid arthritis patients can safely transition from the intravenous form of the IL-16 blocker to the injectable version.

Ogata A, Atsumi T, Fukuda T, et al., Results of switching from intravenous to subcutaneous tocilizumab monotherapy in patients with rheumatoid arthritis: Extension of the MUSASHI study. Arthritis Care & Research. 2015. Accepted article. Online April 1, 2015. DOI: 10.1002/acr.22598.

Rheumatoid arthritis (RA) patients who trade in their intravenous tocilizumab (Actemra) for the subcutaneous form (TCZ-SC) see no loss in efficacy with only minor safety issues, Japanese investigators say.

An 84-week open-label extension trial of TCZ-SC shows the IL-16 blocker’s effectiveness held firm for 6 months in RA patients after making the switch from monthly weight-based infusions to biweekly at fixed-dose injections.

Last week, British researchers reported that injectable TCZ was as safe and effective as the original IV version for treating RA unresponsive to other therapies.

In the Japanese phase III, multicenter double-dummy, non-inferiority study (called MUSHASHI), 322 patients with inadequate response to methotrexate (MTX) or anti-tumor necrosis factor (TNF)-α inhibitors were initially given 162 mg TCZ-IV every 2 weeks.

Women with a mean age of 52 made up the majority of the patient population. Average disease duration came in at 8 years.

At 6 months, half (n=160) were randomly assigned to receive TCZ-IV at 8 mg per kg of body weight every 4 weeks (with a dummy SC injection every 2 weeks) for another 6 months while the rest remained on TCZ-SC.

After investigators evaluated the effects of the switch at 24 weeks, all patients went on TCZ-SC for another 3 months in an open-label extension of the trial.

The upshot: mean disease activity in 28 joints (DAS28) scores were similar in both groups after 84 weeks.

Among those who had been switched from TCZ-SC to IV, the mean disease activity in 28 joints (DAS28) score was 2.5 after 6 months and stayed around 2.6 for the next 3 months.

Among those who stayed on TCZ-SC for the entire 84 weeks, the mean DAS28 was 2.7 at 6 months, and 2.6 after the extra 3 months.

Other efficacy measures also were similar, and safety profiles did not differ. As with the British study, mild injection site reactions is the most prevalent drawback of the subcutaneous version, but none of the patients left the study because of this adverse event, the group from Japan state.

In less positive news, the drug lost some of its effectiveness in the heaviest RA patients (those weighing 154 pounds or more; body mass index >25 kg/m2) Specifically, serum concentrations dropped by half (90.9% to 45.5%).

While some patients developed antibodies to the drug during the monotherapy phase, only one patient in the IV group developed such antibodies and the drug’s effectiveness was maintained after the switch.

The study was limited by the lack of long-term data, the investigators note, so longer-term studies are needed.