Category: Federal Forum Posters
Purpose: In recent years, studies about therapeutic drug monitoring for biopharmaceuticals have been carried out in rheumatoid arthritis, inflammatory bowel disease and psoriasis. These studies shown a relationship between clinical response and serum concentrations. However, the studies on clinical relevance of therapeutic drug monitoring for ustekinumab in patients with psoriasis are particularly scarce. Our objective is to analyze the trough concentrations of ustekinumab in patients with moderate to severe plaque psoriasis with good response.
Methods: Observational retrospective study of all psoriatic patients treated with ustekinumab and monitored in the Pharmacy Service was carried out from September 2017 - February 2018. All patients should present a Psoriasis Area Severity Index (PASI) less than 3 maintained for at least 6 months (good responders). The ethics committee approved this study. The informed consent was obtained for all subjects before entry in the study. Patients received ustekinumab 45 mg every 12 weeks if weight <100 kg, and 90 mg every 12 weeks if weight> 100 kg after dosage regimen induction. Patients should have been treated with ustekinumab for at least 1 year. The serum levels of ustekinumab were assessed immediately prior to the administration of the drug (Ctrough), after pharmacist interview. The concentrations of ustekinumab were quantified by capture ELISA immunoassay (Triturus® analyzer).
Data collected: sex, age, weight, date diagnosis psoriasis, diagnosis psoriatic arthritis (PA), previous treatment with biologist drugs, duration of ustekinumab treatment, dosage (mg and mg/Kg), concomitant treatment (immunosuppressive drugs, topical corticosteroid and/or oral, retinoids) PASI scale before start of ustekinumab treatment (PASIu) and at blood extraction time (PASIe), ustekinumab concentration.
Statistics: descriptive analysis of variables (SPSS version 19.0); quantitative variables (median/range) and qualitative (percentage).
Results: 29 patients (62.1% men). Age: 51 (35-79) years old. Weight 80 (51-117) Kg, 6 patients> 100 Kg. Time since diagnosis 23 (4-58) years. 10.3% PA. 72.4% previously treated with anti-tumor necrosis factor (anti-TNF) drugs (19/20 etanercept, 8/20 adalimumab, 4/20 infliximab). Treatment time: 67.3 (6.0-108) months. Dosage: 23 patients 45 mg, 6 patients 90 mg; 1.6 (1.0-2.0) mg/Kg. Concomitant treatment: 1-acitretin, 1-methotrexate. PASI values: PASIu 10.7 (4.7-26.6); PASIe 0.0 (0.0-3.0), 24/29 patients PASIe 0.0. Ustekinumab concentration 0.75 (0.22 - 5.0) mcg/ml; Comparison ustekinumab concentration dose 45 mg vs 90 mg: 0.75 (0.22 - 5) mcg/ml vs 0.90 (0.24 - 2.8) mcg/ml (p> 0.05). The concentrations of ustekinumab obtained in our patients were higher than published in summary of product characteristics at steady state: dose 45 mg median 0.75 vs 0.21-0.26 mcg/ml; 90 mg dose, median 0.90 vs 0.47-0.49 mcg/ml. A negative correlation was found between ustekinumab concentrations and the dose/weight ratio (mg/kg), but no statistical significance was found (correlation coefficient -0.32, p> 0.05).
Conclusion: Drug concentration was detected in all patients. No relationship was found between ustekinumab concentration and dosage administered. However, there seems to exists a negative correlation between them. Further researchs are needed to determine the clinical significance between ustekinumab concentration and clinical response, and hence the usefulness of therapeutic drug monitoring in psoriasis patients treated with ustekinumab.
Laida ElberdÃn Pazos– Hospital Pharmacist, Xerencia Xestión Integrada A Coruña, A Coruña, Galicia, Spain