Association of adalimumab trough concentrations and treatment response in patients with Juvenile Idiopathic Arthritis

Prospective study to characterize adalimumab exposure in pediatric patients with rheumatic diseases

BACKGROUND

In pediatric rheumatic diseases (PRD), adalimumab is dosed using fixed weight-based bands irrespective of methotrexate co-treatment, disease activity (DA) or other factors that might influence adalimumab pharmacokinetics (PK). In rheumatoid arthritis (RA) adalimumab exposure between 2-8 mg/L is associated with clinical response. PRD data on adalimumab is scarce. Therefore, this study aimed to analyze adalimumab PK and its variability in PRD treated with/without methotrexate.

METHODS

A two-center prospective study in PRD patients aged 2-18 years treated with adalimumab and methotrexate (GA-M) or adalimumab alone (GA) for ≥ 12 weeks was performed. Adalimumab concentrations were collected 1-9 (maximum concentration; Cmax), and 10-14 days (minimum concentration; Cmin) during ≥ 12 weeks following adalimumab start. Concentrations were analyzed with enzyme-linked immunosorbent assay (lower limit of quantification: 0.5 mg/L). Log-normalized Cmin were compared between GA-M and GA using a standard t-test.

RESULTS

Twenty-eight patients (14 per group), diagnosed with juvenile idiopathic arthritis (71.4%), non-infectious uveitis (25%) or chronic recurrent multifocal osteomyelitis (3.6%) completed the study. GA-M included more females (71.4%; GA 35.7%, p = 0.13). At first study visit, children in GA-M had a slightly longer exposure to adalimumab (17.8 months [IQR 9.6, 21.6]) compared to GA (15.8 months [IQR 8.5, 30.8], p = 0.8). Adalimumab dosing was similar between both groups (median dose 40 mg every 14 days) and observed DA was low. Children in GA-M had a 27% higher median overall exposure compared to GA, although median Cmin adalimumab values were statistically not different (p = 0.3). Cmin values ≥ 8 mg/L (upper limit RA) were more frequently observed in GA-M versus GA (79% versus 64%). Overall, a wide range of Cmin values was observed in PRD (0.5 to 26 mg/L).

CONCLUSION

This study revealed a high heterogeneity in adalimumab exposure in PRD. Adalimumab exposure tended to be higher with methotrexate co-treatment compared to adalimumab monotherapy although differences were not statistically significant. Most children showed adalimumab exposure exceeding those reported for RA with clinical response, particularly with methotrexate co-treatment. This highlights the need of further investigations to establish model-based personalized treatment strategies in PRD to avoid under- and overexposure.

TRIAL REGISTRATION

NCT04042792 , registered 02.08.2019.

Pediatric uveitis: Role of the pediatrician

The challenges of childhood uveitis lie in the varied spectrum of its clinical presentation, the often asymptomatic nature of disease, and the evolving nature of the phenotype alongside normal physiological development. These issues can lead to delayed diagnosis which can cause significant morbidity and severe visual impairment. The most common ocular complications include cataracts, band keratopathy, glaucoma, and macular oedema, and the various associated systemic disorders can also result in extra-ophthalmic morbidity. Pediatricians have an important role to play. Their awareness of the various presentations and etiologies of uveitis in children afford the opportunity of prompt diagnosis before complications arise. Juvenile Idiopathic Arthritis (JIA) is one of the most common associated disorders seen in childhood uveitis, but there is a need to recognize other causes. In this review, different causes of uveitis are explored, including infections, autoimmune and autoinflammatory disease. As treatment is often informed by etiology, pediatricians can ensure early ophthalmological referral for children with inflammatory disease at risk of uveitis and can support management decisions for children with uveitis and possible underling multi-system inflammatory disease, thus reducing the risk of the development of irreversible sequelae.