Presentation (CTI)

OBJECTIVES: Adult growth hormone deficiency (AGHD) is a rare endocrine disorder causing significant metabolic and health-related quality-of-life impairments. Lonapegsomatropin, a once-weekly growth hormone therapy, approved for pediatric growth hormone deficiency in US and EU, was FDA-approved in 2025 for AGHD following positive phase 3 foresiGHt trial results. The current budget impact analysis evaluated the introduction of lonapegsomatropin for AGHD to a US payer formulary.
METHODS: An MS Excel model was built to simulate a 1 million‑member plan over 5 years, comparing the current environment (daily growth hormone and weekly somapacitan) with a new environment including lonapegsomatropin. Inputs were drawn from published and internal data and included drug acquisition costs (ProspectoRx) and healthcare resource utilization (inpatient, emergency department, outpatient, and pharmacy). Uncertainty was assessed through deterministic sensitivity analyses and predefined scenarios.
RESULTS: With 3-5% lonapegsomatropin uptake taken directly from somapacitan over the 5-year time horizon, cumulative savings of $2,316 were observed (Per Member Per Month $0.00; Per Patient Per Month -$8.70) indicating minimal financial burden to US payers. Savings were primarily due to substitution from somapacitan under real-world dosing alignment and undiscounted wholesale acquisition cost price. The largest absolute costs were non‑drug healthcare costs (ie, inpatient, emergency department, outpatient, and pharmacy costs), although they were assumed equal across arms. Scenario findings were coherent with priors: higher lonapegsomatropin trial dosing or uptake sourced from daily growth hormone increased costs, whereas somapacitan-trial-aligned dosing for all products and 5% annual price inflation enhanced savings. Sensitivity analyses identified population parameters (eg, AGHD prevalence and treatment-eligible population) as the most influential parameters affecting budget impact outcomes.
CONCLUSIONS: Lonapegsomatropin is budget‑neutral to budget‑favorable during the 5-year period investigated, when replacing somapacitan. These findings support the economic viability of expanding the indication for lonapegsomatropin to AGHD. Future work should incorporate net prices/rebates and treatment‑specific utilization linked to persistence/adherence to refine payer‑relevant estimates.