Time to improvement of pain, morning stiffness, fatigue, and disease activity in patients with ankylosing spondylitis treated with tofacitinib: a post hoc analysis.

Background: Tofacitinib is an oral Janus kinase inhibitor for treatment of ankylosing spondylitis (AS). Time to improvement in core domains of AS was estimated in tofacitinib-treated patients with AS.

Methods: This post hoc analysis used phase 3 trial data from patients with AS receiving tofacitinib 5 mg twice daily or placebo to week (W)16; all patients received open-label tofacitinib W16-48.

Outcomes: nocturnal pain; total back pain; fatigue, spinal pain, peripheral joint pain/swelling, enthesitis, and morning stiffness (Bath AS Disease Activity Index [BASDAI] questions 1-6); BASDAI total score; AS Disease Activity Score (ASDAS). Median time to improvement events was estimated using non-parametric Kaplan-Meier models. Improvement events were defined as initial (first post-baseline observation) and continued (sustained for 2 consecutive visits) ≥ 30% and ≥ 50% improvement in back/nocturnal pain or BASDAI questions/total scores, or ASDAS improvement ≥ 1.1 and ≥ 2.0 points.

Results: 269 patients (tofacitinib: n = 133; placebo-to-tofacitinib: n = 136) were assessed. Median time to improvement was shorter, and more patients experienced improvements with tofacitinib vs. placebo-to-tofacitinib; differences observed from W2 (first post-baseline assessment). Median time to initial (continued) ≥ 30% pain improvement was 4 (4-8) weeks for tofacitinib vs. 24 (24) weeks for placebo-to-tofacitinib (8 [8] weeks post-switch). Median time to initial (continued) ≥ 50% improvement of pain, peripheral joint pain/swelling and enthesitis, morning stiffness, BASDAI total score, and fatigue was 8-24 (12-40) weeks with tofacitinib vs. 24-32 weeks (32 weeks-not estimable [NE]) with placebo-to-tofacitinib. Median time to initial (continued) ASDAS improvement ≥ 1.1 points was 4 (8) weeks for tofacitinib vs. 24 (24) weeks for placebo-to-tofacitinib, and NE for improvement ≥ 2.0 points with either treatment.

Conclusions: Improvements in AS core domains occurred more rapidly with tofacitinib vs. placebo-to-tofacitinib. Half of tofacitinib-treated patients with AS will likely experience improvements ≥ 30% in pain and ≥ 1.1 points in ASDAS during month (M)1, ≥ 50% improvement in nocturnal pain and enthesitis by M2, and in morning stiffness by M3. Results show that initiating tofacitinib as soon as possible is associated with quicker improvements in AS core domains vs. delaying treatment.

Trial registration: ClinicalTrials.gov, NCT03502616, 11 April 2018.