Certolizumab pegol
The TNF inhibitor is already approved for ankylosing spondylitis, among other indications, but it has now demonstrated efficacy and safety in nonradiographic SpA in a phase 3 trial structured with guidance from the Food and Drug Administration.
“It seems likely that UCB will get the indication for this,” according to Dr. Ruderman.
This 317-patient trial was remarkable in that it entailed a full 52 weeks of double-blind therapy with certolizumab at the standard dose of 200 mg every 2 weeks or placebo. The ASDAS Major Improvement rate, defined as at least a 2-point improvement from baseline, was 47% in the active treatment arm, compared with 7% on placebo. The Assessment in Ankylosing Spondylitis International Society 40% (ASAS 40) response rate, a more patient-reported outcome measure, was 57% in the certolizumab group and 16% in controls in this trial, which was recently published (Arthritis Rheumatol. 2019 March 8. doi: 10.1002/art.40866). All participants had to have baseline MRI evidence of sacroiliac joint inflammation and/or an elevated C-reactive protein.
By way of background, Dr. Ruderman explained that the FDA required 52 weeks of double-blind, placebo-controlled therapy because the agency’s advisory committee had formerly expressed reservations about considering an expanded indication for TNF inhibitors in nonradiographic as opposed to radiographic SpA.
“They were very concerned that approval could result in patients with mechanical back pain or fibromyalgia being treated with biologics. And they weren’t sure nonradiographic SpA was a discrete entity. They wondered if it remits on its own,” according to the rheumatologist.
Dr. Ruderman is curious to see how the FDA is going to handle this situation in light of the positive phase 3 certolizumab results. Will the agency require other companies that market TNF inhibitors to mount a similarly rigorous 52-week, double-blind, placebo-controlled trial in order to obtain an expanded indication? That would seem to pose ethical issues now. Or will the companies be able to gain an expanded indication by retrospective analysis of outcomes in patients with nonradiographic SpA in their existing trials databases? Stay tuned.
Ixekizumab
The COAST-V trial was a phase 3, randomized, double-blind, active- and placebo-controlled trial of 341 patients with radiographic SpA who hadn’t previously been treated with a biologic disease-modifying antirheumatic drug. They were assigned to 80 mg of ixekizumab every 2 weeks, 80 mg every 4 weeks, adalimumab (Humira) at 40 mg every 2 weeks, or placebo. The primary endpoint – an ASAS 40 response at week 16 – was achieved in 52% of patients on ixekizumab every 2 weeks, 48% of those who received ixekizumab every 4 weeks, 36% on adalimumab, and 18% on placebo (Lancet. 2018 Dec 8;392[10163]:2441-51).
In contrast, the phase 3 COAST-W trial included 316 patients with radiographic SpA who were inadequate responders or intolerant to one or more prior anti-TNF agents. The 16-week ASAS 40 response rate was 30.6% with ixekizumab every 2 weeks, similar at 25.4% with ixekizumab every 4 weeks, and 12.5% with placebo (Arthritis Rheumatol. 2018 Oct 20. doi: 10.1002/art.40753).
While the COAST-V trial convincingly showed both ixekizumab and adalimumab were more effective than placebo, the patient numbers were way too small to draw any conclusions about the relative efficacy of the two biologics, according to Dr. Ruderman.
“I don’t think these results are surprising,” Dr. Kavanaugh commented. “It would have been surprising if ixekizumab was ineffective, given that secukinumab works. But it’s nice to have the proof.”