SAT-216 New Long Acting Growth Hormone (Lonapegsomatropin) Induced Adverse Effects: A Pediatric Case Series

Abstract Disclosure: V.S. Knight: None. R.S. Newfield: None. M.E. Patterson: None. M. Marinkovic: None. Introduction: Daily growth hormone (GH) has been the mainstay treatment of growth hormone deficiency (GHD) since 1985; however, daily injections can be a barrier to patient adherence. Lonapegsomatropin (Skytrofa™) is the first once-weekly GH therapeutic that was FDA-approved for pediatric GHD in 2021. It is a prodrug with a half-life of approximately 25 hours therefore allowing convenient, weekly dosing. Wider, real world use of weekly GH lonapegsomatropin revealed additional side effects related to treatment that we are hereby presenting. Clinical Case: We completed a retrospective chart review of seven patients with GHD who experienced adverse events related to lonapegsomatropin with some patients requiring change in therapy. Patients were seen at a single pediatric center between 2021 and 2024. IRB approval was obtained. Of seven patients, average age 8.2 years (age range 4.9-13.8 years, six males), three were GH treatment naive and four were previously on daily GH injections. Adverse reactions included: three cases of lipoatrophy, one case of marked behavioral changes, and three patients with hypersensitivity reactions including edema, rash, and pruritus. Two patients had systemic allergic reactions requiring urgent care treatment. Ultimately, two patients switched to different weekly GH product, three to daily GH injections, one remained on lonapegsomatropin, and one patient discontinued treatment and follow ups. Conclusion: In our case series, reactions to newer weekly GH injections ranged from behavioral to systemic. Most adverse effects were mild and resolved after stopping the medication or with injection site rotation. To minimize the risk of lipoatrophy due to the lipolytic effect of GH, it is crucial to stress the importance of rotating the injection site. Physicians should be aware of potential side effects associated with lonapegsomatropin and counsel families about them. Presentation: Saturday, July 12, 2025