Abstract Background Ustekinumab (UST) is an effective biologic therapy for Crohn’s disease (CD). However, it remains unclear whether therapeutic drug monitoring through plasma levels (USTTL) could be useful for guiding treatment. Methods Prospective observational study including patients from the healthcare area of Virgen Macarena University Hospital in Seville with Crohn’s disease receiving maintenance treatment with ustekinumab in January 2024. USTTL were measured at the start of the study (USTP1) and after 12 months (USTP2). At both time points, epidemiological variables and disease activity parameters were collected, including clinical activity with Harvey–Bradshaw Index (HBI), assessed through a nurse-administered questionnaire, and biochemical activity with C-reactive protein (CRP) and fecal calprotectin (FCP). Results A total of 75 patients with CD were included. 36% had undergone surgery, and 88% and 37.4% had received at least one first- or second-line biologic therapy, respectively. At baseline, the median HBI was 6 (3–10), with 38.7% of patients in clinical remission, 62.6% in biological remission, and a median USTP1 of 5.3 (3.0–8.2) μg/mL. It was observed that patients who achieved biological response or remission after one year (P2) had higher baseline USTP1 levels than those who did not (6 vs. 2.8 μg/mL for response and 6.3 vs. 3 μg/mL for remission; p = 0.003 in both comparisons). ROC curves were calculated, with USTP1 cut-off values of 3.46 μg/mL and 3.765 μg/mL for biological response and remission at P2, respectively (figure 1). At the end of follow-up, 57 patients remained on UST therapy, and a second measurement (USTP2) was obtained in 59 patients. Among the 28 patients who were not in biological remission at P1, 15 achieved it later (51.7%), 11 of them under intensified regimens. In this subgroup of patients with two measurements, significantly higher rates of clinical remission (69.1% vs. 47.3%) and biological remission (78.3% vs. 60.9%) were observed at the end of follow-up compared with baseline, along with higher UST levels (9.1 vs. 5.5 μg/mL), as shown in table 1. Patients receiving intensified treatment regimens at P2 had higher USTP2 values: 6.2 μg/mL (3.9–9.0) with subcutaneous (SC) dosing every 6–8 weeks, 9.8 μg/mL (5.6–13.7) with SC every 4–6 weeks, and 20 μg/mL (12.2–20) with intravenous administration every 4 weeks. Conclusion High UST trough levels during maintenance are associated with an increased likelihood of biological response and remission in Crohn’s disease, particularly in the context of treatment intensification. Conflict of interest: González Antuña, Jaime: No conflict of interest Rodríguez Gallardo, María: None Valdes, Teresa: none Belvis Jiménez, María Inmaculada: No conflict of interest Maldonado Pérez, María Bélen: No conflict of interest Romero González, María: No conflict of interest Merino Bóhórquez, Vicente: No conflict of interest Calleja Hernández, Miguel Ángel: No conflict of interest Argüelles Arias, Federico: I have recivied research support or speaker bureau from AbbVie, Amgen, AstraZeneca, Celltrion, Ferring, Falk Pharma, Alfa Sigma, Janssen/J&J, Neopharm, Pfizer, MSD, Takeda, STADA Arzneimittel, Sandoz, Lilly
Antuña et al. (Thu,) studied this question.