Encouraging results for subcutaneous abatacept in patients with polyarticular JIA
medwireNews: Results of an open-label phase III study suggest that subcutaneous abatacept is a feasible treatment option for children and adolescents with polyarticular-course juvenile idiopathic arthritis (pJIA).
In the single-arm trial, patients from 48 centers worldwide who had a previous inadequate response or intolerance to at least one conventional or biologic DMARD were given weekly weight-tiered doses of abatacept (10 to <25 kg: 50 mg dose; 25 to <50 kg: 87.5 mg dose; ≥50 kg: 125 mg dose) for 4 months. After this timepoint, patients who achieved a JIA–ACR30 response could continue receiving the same treatment for a further 20 months. Participants were separated into two cohorts based on age (2–5 years and 6–17 years).
At the 4-month follow-up, the abatacept steady-state serum trough concentration was “consistent and above the target therapeutic exposure of 10 μg/ml” in both age cohorts, report the researchers, with median values of 40.5 µg/mL for the 135 patients aged 6 years and over, and 51.2 µg/mL for the 30 children in the younger cohort. The corresponding concentrations at the 2-year follow-up were 43.0 and 58.7 µg/mL.
These pharmacokinetic data “confirm the feasibility of the weekly weight-tiered [subcutaneous] abatacept treatment regimen for pJIA in 2–17-year-old patients,” write Hermine Brunner (Cincinnati Children’s Hospital Medical Center, Ohio, USA) and co-investigators.
The team also found that abatacept improved JIA symptoms, with 83% of patients aged 6–17 years and 89% of those in the younger age group having a JIA–ACR30 response at month 4, and a corresponding 58% and 100% meeting this endpoint at 2 years.
A total of 87.9% of patients in the older cohort and 93.5% of those in the younger cohort experienced adverse events (AEs), and rates of serious AEs were 8.1% and 6.5%, respectively. Two serious AEs – one case of sepsis and one overdose due to misclassification by weight – were considered by the investigators to be related to the study drug.
Brunner and team note that there were no reports of opportunistic infections related to abatacept, even in settings with a high tuberculosis burden, and summarize that the drug was “well tolerated in both cohorts, with no new safety concerns observed.”
The investigators caution that their study had some limitations, including its open-label design and potential confounding by the use of concomitant medications. They also highlight that a protocol violation occurred, resulting in five patients with undifferentiated and persistent oligoarthritis enrolling in the study even though they did not meet the eligibility criteria.
Nonetheless, they conclude in Arthritis & Rheumatology that subcutaneous abatacept “provides an effective and well-tolerated treatment option for patients with pJIA, with the additional benefit of the convenience associated with self- or parent/caregiver administration.”
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