{ "abstract": "Objective: This study aimed to clarify the association between longitudinal adalimumab concentrations, anti-adalimumab antibodies (AAA) levels, and clinical response in Chinese patients with ankylosing spondylitis (AS).\n\nMethods: A prospective multi-center, observational cohort study of AS patients receiving adalimumab therapy was conducted. Disease activity was assessed with the AS Disease Activity Score (ASDAS), and clinical responders were defined based on ASDAS improvement together with C-reactive protein normalization. Adalimumab concentrations were measured using a validated sandwich immunoassay. Measurement of AAA levels was performed with a laboratory-developed immunoassay system integrating electrochemiluminescence technology with specific immunomagnetic separation, with result reported as signal-to-noise ratio (S/N).\n\nResults: A total of 140 patients receiving adalimumab monotherapy were included. The median follow-up period was 169 days, and 711 plasma samples were available for adalimumab concentrations and AAA levels measurements. Seven patients had pre-existing AAA, and 120 (90.2%) of the remaining 133 patients tested positive for AAA during follow-up. A total of 48 patients were excluded from the exposure–response relationship dataset owing to pre-existing AAA (n=7), lack of active disease (n=26), incomplete follow-up (n=8), and prolonged dosing intervals (n=7). Among the remaining 92 patients, a total of 58 (63%) achieved clinical response. Adalimumab concentrations were higher, and AAA levels were significantly lower, in responders compared with non-responders at multiple time points. Exposure–response relationship models also revealed a steady-state adalimumab concentration target of 5.1 μg/mL and a week-4 concentration target of 3.3 μg/mL, corresponding to an 80% probability of clinical response. Thirty-six of 92 patients (39.1%) exhibited AAA-S/N values exceeding the putative clinically meaningful threshold (AAA-S/N=10). Patients in the high-AAA group (AAA-S/N≥10) had lower drug levels (median: 1.5 μg/mL vs. 6.9 μg/mL, P< 0.0001) and poorer response rates (38.8% vs. 78.6%, P = 0.0002), relative to those in the low-AAA group (AAA-S/N<10). Furthermore, patients who were week-4 AAA-positive exhibited a 1.8-fold increased risk of non-response (relative risk, 95% confidence interval, 1.1–2.8).\n\nConclusions: Our results demonstrate that longitudinal profiles of adalimumab concentrations and AAA levels show a strong association with clinical responses in this Chinese AS cohort, which may inform therapeutic drug monitoring–guided adalimumab treatment strategies that remain to be further validated.\n\nTrial registration: ClinicalTrials.gov (NCT04875299).", "abstract_shown": true, "affiliations": [ "Department of Pharmacy, The First Affiliated Hospital of Soochow University , ,", "Department of Rheumatology, The First Affiliated Hospital of Soochow University , ,", "Department of Pharmacy, The Second Xiangya Hospital, Central South University , ,", "Department of Rheumatology and Immunology, The Second Xiangya Hospital, Central South University , ,", "Department of Rheumatology and Immunology, The Third Affiliated Hospital of Soochow University , ,", "Department of Pharmacy, The Third Affiliated Hospital of Soochow University , ,", "Department of Rheumatology, Shanghai Guanghua Hospital, Shanghai University of Traditional Chinese Medicine , ," ], "article_type": "research article", "arxiv": null, "author_total": 14, "authors": [ { "affs": [ 0 ], "name": "Xiaoliang Ding" }, { "affs": [ 0 ], "name": "Ling Xue" }, { "affs": [ 1 ], "name": "Mingjun Wang" }, { "affs": [ 0 ], "name": "Shizheng Pan" }, { "affs": [ 2 ], "name": "Bikui Zhang" }, { "affs": [ 3 ], "name": "Fen Li" }, { "affs": [ 4 ], "name": "Yingchun Ma" }, { "affs": [ 5 ], "name": "Nan Hu" }, { "affs": [ 6 ], "name": "Dongyi He" }, { "affs": [ 0 ], "name": "Lin Song" }, { "affs": [ 0 ], "name": "Sheng Jiang" }, { "affs": [ 0 ], "name": "Shengxiong Zhu" }, { "affs": [ 1 ], "name": "Jian Wu" }, { "affs": [ 0 ], "name": "Liyan Miao" } ], "bibtex": "https://research.draconitic.com/paper/dbszjxh9nrcqw.bib", "cited_by": 0, "doi": "10.3389/fimmu.2026.1893483", "fulltext_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13668797/?tool=EBI", "id": "dbszjxh9nrcqw", "issns": [ "1664-3224" ], "landing_url": "https://europepmc.org/article/PMC/PMC13668797", "language": "eng", "licence": "CC-BY", "licence_label": "CC BY", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "2745|Spondyloarthritis Studies and Treatments" ] ], "openalex": "W7215090622", "pdf_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13668797/pdf/?tool=EBI", "pmcid": "PMC13668797", "pmid": null, "published": "2026-10-01", "publisher": "Frontiers Media SA", "ris": "https://research.draconitic.com/paper/dbszjxh9nrcqw.ris", "sources": [ { "first_seen": "2026-10-30T12:18:25Z", "native_id": "PMC:PMC13668797", "source": "europepmc", "url": "https://europepmc.org/article/PMC/PMC13668797" }, { "first_seen": "2026-10-30T12:19:15Z", "native_id": "10.3389/fimmu.2026.1893483", "source": "crossref", "url": "https://www.frontiersin.org/articles/10.3389/fimmu.2026.1893483/full" } ], "subjects": [ { "field": "biology", "origin": "issn:1664-3224", "subfield": "immunology" } ], "title": "Longitudinal monitoring of adalimumab levels and anti-adalimumab antibodies in Chinese patients with ankylosing spondylitis: a prospective cohort study", "title_text": "Longitudinal monitoring of adalimumab levels and anti-adalimumab antibodies in Chinese patients with ankylosing spondylitis: a prospective cohort study", "type": "peer-reviewed", "updated_at": "2026-10-30T12:19:15Z", "url": "https://research.draconitic.com/paper/dbszjxh9nrcqw", "venue": "Frontiers in immunology", "versions": [] }