Model-based precision dosing of sirolimus in pediatric patients with vascular anomalies

Area of Science:

• Pharmacology
• Pediatrics
• Vascular Biology

Background:

• Sirolimus is the first effective drug for complicated vascular anomalies.
• Precision dosing strategies are crucial for pediatric drug efficacy.

Purpose of the Study:

• To refine a pharmacokinetic (PK) model-based strategy for sirolimus precision dosing in pediatric patients with vascular anomalies.
• To analyze 12-month follow-up data from a Phase 2 clinical trial to assess target attainment and inform dosing adjustments.

Main Methods:

• Population pharmacokinetic (PK) analysis using nonlinear mixed-effects modeling (NONMEM) with 676 blood concentration data points.
• Incorporation of a maturation function for sirolimus clearance and allometric scaling for body weight.
• Analysis of data from 52 pediatric patients aged 3 weeks to 18 years.

Main Results:

• Achieved 94% target attainment (49/52 patients) within 2-3 months of therapy across a wide pediatric age range.
• Established age-specific dosing ranges: ~1.8 mg/m² twice daily for >2 years, and 0.7-1.6 mg/m² twice daily for 3 weeks to 2 years.
• Mean allometrically scaled sirolimus clearance increased from 3.9 L/h at birth to 18.5 L/h in patients over 2 years.

Conclusions:

• The developed PK model-based dosing strategy enables precise sirolimus therapy in pediatric patients with vascular anomalies.
• This approach provides a foundation for understanding sirolimus exposure-response and clinical outcomes from birth through adolescence.
• Optimized dosing enhances treatment efficacy and safety for children with complex vascular conditions.