csDMARDs Could Add to TNF Inhibitors' Benefits in SpA

Sara Freeman

September 16, 2021

Better retention and remission rates with tumor necrosis factor inhibitors (TNFi) have been observed in patients with spondyloarthritis (SpA) who were also treated with a conventional synthetic disease-modifying antirheumatic drug (csDMARD) rather than monotherapy.

Data from the EuroSpA Research Collaboration have shown that 82% of patients who received TNFi and csDMARD cotherapy were still taking their TNFi at 1 year versus 79% of those who were taking the biologic alone (P < .001).

Combination therapy led to remission in 21.8%, compared with TNFi monotherapy at 19.5% (P < .0001), with rates of remission according to Ankylosing Spondylitis Disease Activity Score <1.3 (23.7% vs. 21.8%, P = .011) and Bath Ankylosing Spondylitis Disease Activity Index <2 (5.9% vs. 7.7%, P < .0001) also favoring the cotherapy group.

"We did see a considerable heterogeneity across the countries in this study, both in the use of csDMARD therapy and in the TNF [inhibitor] retention," Michael J. Nissen, MBBS, FRACP, MD, a rheumatologist at the University of Geneva, said in an oral abstract presentation at the 12th International Congress on Spondyloarthritides.

"Overall, the 1-year TNFi retention was better with cotherapy, particularly in countries in the Scandinavian region and Switzerland," Nissen observed.

"The csDMARD cotherapy significantly improved remission; we could perhaps argue whether these small differences are clinically meaningful, but they were highly significant in the study."

Why Look at csDMARD and TNFi Cotherapy?

European guidelines suggest that csDMARDs are not that useful for treating people with SpA, stating that they should not be used in axial disease and used only as monotherapy in those with peripheral disease.

"Nevertheless, these medications are often used, which begs us to ask the question why is that the case?" Nissen said.

As previous work by Nissen and others had suggested that there might be a benefit of combining a csDMARD and a TNFi, the aim was to build upon this and see if looking at a very large patient population might be able to provide some clear answers.

The analysis included data from 13 European registries and more than 24,000 patients who had started their first TNFi between 2006 and 2017. The mean age of the study population was 42.5 years, and 58% were male, with an average disease duration of 5.9 years. Nearly one-third of patients were receiving comedication with a csDMARD, although this ranged from 13.5% to 71.2% depending on the country.

The most frequently used TNFi were adalimumab (31% of patients overall), etanercept (24%), and infliximab (25%), and the most-used csDMARDs were methotrexate (56%) and sulfasalazine (45%).

The effectiveness of treatment in achieving clinical remission was examined according to the TNFi used and for the use of csDMARDs.

"We found that sulfasalazine and methotrexate were similarly effective in terms of improving outcomes in addition to a TNF inhibitor," Nissen said. For example, the adjusted odds ratios for using sulfasalazine or methotrexate with infliximab were a respective 1.32 and 1.37, and the aORs for uses these specific csDMARDs with etanercept were 1.38 and 1.35.

The researchers reported finding significantly higher aORs if both sulfasalazine and methotrexate were used with a TNFi (1.67 for any TNFi, 1.95 for infliximab, 1.45 foretanercept, and 1.85 for adalimumab).

This perhaps suggests "there's some role for combining csDMARDs to have an even greater effect," Nissen put forward.

A "Very Provocative Conclusion"

That's "a very provocative conclusion" commented Robert Landewé, MD, PhD, of Amsterdam University Medical Center who chaired the sessions. "You can see it by the [number] of people that want to ask questions."

Dr Robert Landewé

Désirée van der Heijde, MD, PhD, of Leiden (the Netherlands) University Medical Center, commented these data were "timely as we are updating the ASAS/EULAR [Assessment of SpondyloArthritis international Society/European Alliance of Associations for Rheumatology] recommendations at the moment." She queried, however, if the differences were clinically significant.

Dr Désirée van der Heijde

"I think if you have a database of 24,000 patients, highly, statistically significant doesn't tell me a lot. So, I want to look at the clinical meaning of the differences. So, if you have a 2% difference in retention rate, is that worth prescribing comedication?" van der Heijde said.

"I think you're absolutely right," Nissen responded. "We're obviously going to find highly significant differences with such a big patient group." While the small statistical differences seen may not look very clinically relevant at face value, they could provide some guidance for clinical decision making.

"It may alter our approach if that patient is already on a csDMARD and has peripheral disease; perhaps there's tendency to then to keep that csDMARD rather than then stopping it and switching to a biologic agent," Nissen argued. It's a topic that has been debated for some time, he added, and further study is needed, but "I think it helps give a little bit more clarity to the idea."

Another point of discussion was the proportion of patients who had "pure axial disease." More patients in the comedication group had peripheral disease, van der Heijde pointed out, "that's also where we expect to see the differences."

Further research is needed, but there doesn't seem to be any impact in terms of the effect on retention, Nissen said, "but it's a little bit harder to interpret for efficacy."

Confounding by indication was another issued raised, which "is very difficult to control for in this type of study," Nissen said.

"The hope is that you have a big enough population" so this doesn't matter, but as is the nature there were lots of missing data that would have been useful to have and adjust for, such as psoriasis and smoking status. There was also no adjustment for the number of patient visits, as it's very different from registry to registry.

Nissen disclosed grant/research support from AbbVie and Novartis. He also acknowledged acting as a consultant or speaker for AbbVie, Celgene, Janssen, Eli Lilly, Novartis, and Pfizer.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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