• autoimmune diseases
• magnetic resonance imaging
• DMARDs (synthetic)
• spondyloarthritis

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a chronic inflammatory disease that severely affects patients’ quality of life. Therapies including tumour necrosis factor inhibitors (TNFi) and bisphosphonates (BPs) yield variable efficacy.1 Tofacitinib, a Janus kinase inhibitor, may suppress osteoclast-mediated joint damage by inhibiting the RANKL pathway.2 A previous study proved the safety and efficacy of tofacitinib in psoriatic arthritis resistant to TNFi over 3 months.3 Additionally, we reported a case where tofacitinib in combination with methotrexate and Tripterygium wilfordii Hook was effective in SAPHO syndrome.4

To further explore tofacitinib efficacy in SAPHO syndrome, we retrospectively reviewed the medical records of patients enrolled from January 2019 to December 2019 in our dynamic cohort of SAPHO syndrome.5 Patients were included if they: (1) received tofacitinib without concomitant TNFi, BPs, or other disease-modifying antirheumatic drugs and (2) had complete clinical data and MRI of SAPHO-related lesions with pain before (within 1 week) and during tofacitinib treatment. The pain visual analogue scale (VAS) score and Health Assessment Questionnaire–Disability Index (HAQ-DI) for individual patients were recorded. The radiological response was based on the regression of inflammatory lesion area shown by bone marrow oedema (BMO) on MRI and assessed by readers blinded to time sequence and clinical data. A good response was defined as complete remission of all lesions, and a moderate or mild response included significant (≥50%) or partial (<50%) resolution of at least one lesion, respectively; no response was designated for stable or worsening existing lesions or when a new lesion developed.

Twelve female patients (table 1), who received 5 mg tofacitinib twice daily continuously during a median follow-up of 3.4 (range 1.9–4.6) months, were included. The patients showed significant improvements in VAS score (6 vs 2, p=0.003) and HAQ-DI (0.45 vs 0.20, p=0.024) (figure 1, online supplementary table 1). Ten patients (83.3%) had ≥50% decrease in VAS score; these included one (patient 5) of the two patients who had an inadequate response to TNFi and three (patients 2, 6, and 12) of the four patients who had an inadequate response to BP. Patients with spinal involvement showed a significant improvement in Bath Ankylosing Spondylitis Disease Activity Index (3.5 vs 1.6, p=0.043) and Bath Ankylosing Spondylitis Functional Index (1.2 vs 0.5, p=0.042). Inflammatory markers also decreased significantly. Nine patients (75.0%) exhibited MRI response, including six (50.0%) of moderate and three (25.0%) of mild (table 1, online supplementary table S2, online supplementary figures S1–S12). The condition of seven of the eight patients with skin lesions alleviated. Six patients (50%) complained of upper respiratory tract infections (without antibiotics prescription) during the treatment. No other adverse event was reported.

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Figure 1

(A) Visual analogue scale (VAS) score for pain, (B) Health Assessment Questionnaire–Disability Index (HAQ-DI), (C) level of high-sensitivity C reactive protein (hs-CRP), (D) level of erythrocyte sedimentation rate (ESR), (E) Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and (F) Bath Ankylosing Spondylitis Functional Index (BASFI) of each patient before and after tofacitinib treatment (Wilcoxon signed-rank test).

Clinical trials have proved tofacitinib efficacy in psoriatic arthritis, ankylosing spondylitis, and plaque psoriasis, which have overlapping features with SAPHO syndrome. Our results first showed the effectiveness of tofacitinib in patients with SAPHO syndrome, evidenced by alleviation of pain and rash, decreased systemic inflammation, improved quality of life, and remission on MRI. Notably, efficacy was observed in patients who had an inadequate response to TNFi or BPs. The effects of tofacitinib on BMO seemed to be less remarkable, which might reflect the discrepancies between clinical and radiological response. Unusually, 50% of patients reported upper respiratory tract infections; however, the risk of severe infection was reported to be low.6 The main limitations of our study are the retrospective design, small sample size, and short follow-up duration. Nevertheless, we provide evidence that tofacitinib may be beneficial for patients with SAPHO syndrome.