Evaluating Sarilumab's Efficacy as a Monotherapy in Rheumatoid Arthritis

Monotherapy was a big topic of conversation at the American College of Rheumatology’s annual meeting, held November 8-13 in Atlanta, Georgia, and 2 abstracts highlight the efficacy of sarilumab as a monotherapy in patients with rheumatoid arthritis (RA).

The first abstract was a post hoc analysis of outcomes among patients who received sarilumab as a monotherapy, patients who received sarilumab plus conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), and patients who discontinued csDMARDs during their sarilumab treatment as part of the EXTEND open-label extension study.¹ The patients had been enrolled in 4 trials studying sarilumab subcutaneously 150 mg or 200 mg twice a week versus either placebo or adalimumab, and then were eligible to receive open-label sarilumab subcutaneously 200 mg every 2 weeks. During the open-label extension, investigators could discontinue csDMARDs at any time.

A total of 42 patients discontinued csDMARDs and began receiving sarilumab as a monotherapy; 1851 patients continued csDMARDs, and 111 received sarilumab as a monotherapy for the entire time they were studied. Response rates were similar among the 3 groups, but group 1 saw a greater incidence of adverse events (AEs) than groups 2 and 3. Rates of infections were highest in the group that continued on csDMARDs (57.9%), with rates lowest among the group who continued with sarilumab as a monotherapy (39.6%).

Overall, patients in the 3 groups had similar clinical responses, whether they had sarilumab as a monotherapy the entire study, discontinued csDMARDs part way through the study and then received sarilumab as a monotherapy, or continued with csDMARDs plus sarilumab the entire time.

The second abstract was a post hoc analysis assessing switching patients from adalimumab as a monotherapy to sarilumab as a monotherapy as part of the open-label extension of MONARCH, which was a head-to-head trial of the 2 therapies.²

Although guidelines recommend that patients with RA who fail to reach low disease activity or remission have their therapy adjusted, patients have a fear that changing treatment may result in clinical worsening.

“No data currently exist that address the likelihood of clinical worsening following a switch in therapy in patients who had a partial response and who did not achieve a predetermined treatment goal,” the authors explained.

In the open-label extension, patients who had been randomized to receive adalimumab subcutaneously 40 mg twice a week were switched to sarilumab subcutaneously 200 mg twice a week. Patients who had been on sarilumab in the blinded phase of the trial continued on sarilumab during the open-label extension to serve as a control group. Only patients in the original double-blinded trial who had a partial, inadequate response were included in the extension study. A total of 155 patients were switched from adalimumab and 165 continued with sarilumab.

There were improvements in disease activity, based on a threshold change in Clinical Disease Activity Index (CDAI) of ±6, in 57% of switch patients and 43% of continuation patients. Clinical worsening occurred in 6% of switch patients and 4% of continuation patients. Based on a CDAI threshold of ±12, 27% (switch) and 53% (continuation) experienced improvements in disease activity compared with clinical worsening in 2% (switch) and 1% (continuation).

“These findings can help inform patients’ and clinicians’ shared decision making when considering changes in RA therapy,” the authors concluded.

1. Curtis JR, Lin Y, Thangavelu K, et al. Withdrawal of conventional synthetic disease-modifying antirheumatic drugs in the sarilumab open-label EXTEND study: efficacy and safety analysis. Presented at: The American College of Rheumatology Annual Meeting; November 8-13, 2019; Atlanta, GA. Abstract 2351.

2. Curtis JR, Aletaha D, Burmester G, et al. Low probability of clinical worsening following switching biologic DMARD in patients with RA and partial response to adalimumab. Presented at: The American College of Rheumatology Annual Meeting; November 8-13, 2019; Atlanta, GA. Abstract 1387.

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