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Pediatric and Adolescent Endocrinology

SUN-201 - Safety and Effectiveness of Lonapegsomatropin in the Skybright Registry: Analysis of the First 100 Patients Enrolled with 2 Years of Follow-Up

Sunday, June 14, 2026
9:00 AM - 4:00 PM CT
Location: ENDOExpo; Poster Floor
Disclosure(s):
Aristides K. Maniatis, MD: Ascendis Pharma: Advisory Board (), Clinical Trial Investigator (), Speakers' Bureau ()
Andrew Dauber, MD, MMSc: Ascendis: Clinical Trial Investigator (), Consultant (); BioMarin: Advisory Board (), Clinical Trial Investigator (), Consultant (), Contracted Research (Principal Investigators must provide information, even if received by the institution) (), Grant Recipient (); Eton Pharmaceutical: Consultant (); Lumos: Clinical Trial Investigator (); Neurocrine: Clinical Trial Investigator (); Novo Nordisk: Clinical Trial Investigator (), Consultant (); Pfizer Inc: Advisory Board (), Clinical Trial Investigator (), Consultant (), Grant Recipient (); QED Pharmaceutical: Advisory Board (), Clinical Trial Investigator (), Consultant (); Sandoz: Consultant ()
Background
Lonapegsomatropin, a prodrug that delivers unmodified somatropin, is FDA approved as a once-weekly treatment for children and adults with growth hormone deficiency (GHD). SkybriGHt is a US-based, multicenter, prospective, long-term study evaluating the safety and effectiveness of lonapegsomatropin in children and adolescents in the post-marketing setting. We report outcomes of lonapegsomatropin treatment for the first 100 individuals enrolled in the registry who reached 2 years of follow-up.

Methods
Children and adolescents receiving lonapegsomatropin as part of standard clinical care are eligible to be invited to participate by their treating health care provider. Target enrollment is 900 individuals. Lonapegsomatropin therapy will be initiated before, and independently of, any consideration of study participation. Enrollment will span 5 years; the study will conclude 10 years after the first participant is enrolled. Descriptive statistics are provided for height standard deviation score (SDS), annualized height velocity (AHV), and IGF-1 SDS. Safety evaluations are based on analysis of adverse events (AEs).

Results
Demographics and baseline characteristics for the first 100 enrolled individuals were previously reported in the 1-year follow-up (Horm Res Paediatr. 2025;98(Suppl 3):1-348. Abst. 1192). Participants were predominantly male (82%) and white (86%), with a mean (SD) age of 11.1 (3.0) years (range, 3.1 to 16.3); 59% had prior GH treatment (median duration of 9.4 months) at the time of initiating lonapegsomatropin. At enrollment, median duration of prior GH treatment (including lonapegsomatropin) was 22 months. The median (IQR) duration of lonapegsomatropin treatment (including treatment before enrollment) was 2.7 (2.1, 3.8) years. The initial prescribed dose of lonapegsomatropin (mean 0.23 mg hGH/kg/week) was maintained at month 24. Height SDS increased from enrollment to month 24 in participants with and without prior GH; overall, mean height SDS increased from −0.59 at enrollment to −0.12 at month 24. Mean (SE) AHV at month 24 was 6.4 (0.3) cm/year. The mean IGF-1 SDS was 1.4 at enrollment and 1.1 at month 24. There were no serious or severe treatment-related AEs, no AEs that led to treatment discontinuation, and no deaths.

Conclusions
This prospective, real-world evaluation examined lonapegsomatropin treatment for children and adolescents with GHD in the first 100 individuals enrolled in the SkybriGHt registry. Prescribed doses remained stable, and AHV was maintained from enrollment to month 24, with continued gains in height SDS. IGF-1 SDS was maintained between 0 and +2.0 SDS, consistent with adequate GH replacement. Safety and efficacy outcomes were comparable to prior clinical trial results, supporting the effectiveness of lonapegsomatropin administered once weekly as part of routine clinical care for children and adolescents with GHD.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*