Magnetic resonance imaging in ankylosing spondylitis: reduction of active sacroiliitis and hip arthritis during treatment with an adalimumab biosimilar

Abstract

Dear editors, Tumor necrosis factor inhibitor (TNFi) biosimilars are crucial in the treatment of ankylosing spondylitis (AS). Most clinical trials compared clinical efficacy, adverse effects, and pharmacokinetics between biosimilars and their originators, but the rare study focused on radiological changes [1]. HS016 is a biosimilar to adalimumab. A phase III clinical trial was conducted to examine the clinical similarity between this drug and its originator (trial registration number: ChiCTR1900022520) [2]. Our center carried out an extended study to evaluate the influence of HS016 on sacroiliitis and hip arthritis using magnetic resonance imaging (MRI). This study was performed from July 2017 to February 2018, while the detailed protocol has been previously described [2]. Eligible participants who fulfilled the modified New York criteria underwent HS016 (Zhejiang Hisun Pharmaceutical Inc. Co., Ltd, China) or originator adalimumab (Humira®) 40 mg subcutaneous injection every other week from baseline to week 24 [2, 3]. Demographic and clinical information were recorded at baseline, while MRI of sacroiliac joints (SIJ) and hips were conducted at baseline and week 24. Two readers blinded to clinical and laboratory information have independently assessed the MRI images, while discrepancies were adjudicated by the third reader. Active sacroiliitis was assessed using the Spondyloarthritis Research Consortium of Canada (SPARCC) SIJ inflammation score [4]. Structural changes were evaluated through the SPARCC SIJ structural score (SSS), which assessed fat metaplasia, bony erosion, backfill, and ankylosis [5]. Each hip was evaluated independently. Hip MRI inflammation scoring system (HIMRISS) was used to investigate the active lesion [6]. Structural changes of hips were defined as bone erosion, fat accumulation, and/or ankylosis [7]. Data analysis was conducted using SPSS 22.0. Continuous data were compared using a t test or Mann-Whitney U test as appropriate. Categorical data were assessed through Fisher’s exact test. Linear mixed models (LMM) were used to evaluate differences in longitudinal data. Radiological indexes were dependent variables, while treatments and visits were independent variables with an unstructured covariance matrix and a restricted maximum likelihood estimate. p < 0.05 was considered statistically significant. Fourteen and 5 AS patients underwent HS016 (HS016 group) or its originator (originator group) treatment. No significant difference was evident between groups (Table 1, p > 0.05). One patient of the HS016 group discontinued the study because of sepsis, so 13 and 5 patients who received HS016 or its originator therapy underwent the final MRI examinations. SPARCC SIJ inflammation score significantly decreased from baseline to week 24 in both groups (Table 2, p < 0.05), but SPARCC SSS insignificantly altered (p > 0.05). No significant differences in SIJ were found between groups (p > 0.05). One patient of the originator group had undergone double hip replacements before this trial, so 26 and 8 hips of these groups were assessed at week 24. HIMRISS significantly reduced (Table 2, p < 0.05), while structural lesion of hip seldom changed (p > 0.05). The influence of treatments on the hips was comparable (p > 0.05). Adalimumab relieves symptoms of AS and alleviates its radiological change [8]. Our study showed active * Tian-Wang Li [email protected]