medwireNews: Patients with psoriatic arthritis (PsA) who have achieved minimal disease activity (MDA) on ixekizumab do better if they continue on the drug rather than stopping treatment, show findings from the SPIRIT-P3 study.
The relapse rate for patients who achieved MDA after 24 weeks of open-label treatment and continued to take the interleukin (IL)-17a inhibitor for 40 weeks was 34%, which was significantly lower than the 73% rate seen among patients who received placebo instead, reported Laura Coates, from the University of Oxford in the UK.
A total of 394 biologic-naive patients with active PsA and an inadequate response or intolerance to at least one conventional synthetic DMARD participated in the phase IIIb study, presented at the 2019 ACR/ARP Annual Meeting in Atlanta, Georgia, USA.
They received ixekizumab 160 mg every 2 weeks for 24 weeks, by which time 158 (40%) patients had achieved MDA, based on meeting at least five of the seven criteria below for at least four visits over 3 consecutive months.
- Tender joint count ≤1
- Swollen joint count ≤1
- PASI total score ≤1 or BSA ≤3%
- Visual analog score (VAS) for pain ≤15
- Patient global disease activity VAS score ≤20
- HAQ-DI ≤0.5
- Tender entheseal points ≤1
These patients were randomly assigned to continue receiving ixekizumab (n=79) or to discontinue the drug and receive placebo (n=79) under double-blind conditions for a further 40 weeks.
Among the patients in the placebo group, the mean time to relapse was 22 weeks, by which time half of the patients had flared, compared with about 30% of those who remained on ixekizumab.
Noting the early drop in the proportion of patients who maintained MDA while still on ixekizumab, Coates explained that this could be evidence of a “nocebo response,” due to the patients switching from open-label “definite” drug to a 50% chance of having their drug stopped.
If patients flared during the course of treatment, open-label ixekizumab was reintroduced straight away and Coates emphasized that “the vast majority” of these patients quickly regained MDA, after about a median of 4 weeks.
The safety profile was “reassuring,” said Coates, and “in keeping with data from ixekizumab trials to date.” There were relatively low rates of serious adverse events and serious infections, and only one case of inflammatory bowel disease.
Coates believes that “continuous ixekizumab is superior and is optimal in terms of maintaining MDA response, but it is clear here that if patients do have treatment interrupted then they stand a very high chance of being able to regain control if the ixekizumab is restarted.”
She added that the study did not look at tapering, which might offer an intermediate option and is worthy of further research.
In an accompanying abstract presented as a poster at the conference, Coates and co-researchers looked at which domains flared when MDA was lost during ixekizumab withdrawal. And they found that relapse occurred in multiple components within individual patients.
Commenting on this, Coates said that skin disease components did not flare any quicker than swollen joint count, and it was more common to see a flare in pain and tender joint count joint, part of which could be attributed to the nocebo effect.
By Lucy Piper
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