ESPE Abstracts

Introduction: Guidelines recommend starting growth hormone (rhGH) as soon as possible in pathological short stature to promote growth and normalize final height. Despite efficacy and safety of rhGH, about 70% of patients have poor adherence to treatment, with consequently reduced therapeutic response. Somatrogon, a weekly long-acting GH (LAGH), may improve the therapy compliance and efficacy, reducing the number of injections. Despite it has been demonstrated to be safe and not inferior to daily GH (dGH), one of the concerns is IGF1 levels during treatment. We aim to describe our approach in managing Somatrogon to identify the most appropriate dose for each subject.

Methods: We report IGF1 levels in 9 children with GHD treated with LAGH, 3 shifting from dGH and 6 naïve, at our Pediatric Endocrinology Unit. After the first month of therapy we performed IGF1 dosage in 2^nd and in 4^th day post injection; after 3 and 6 months, in the 4^th day post injection. Auxological data were reported at starting of therapy and after 3 and 6 months.

Results: Considering the three switched patients, two completed 6 months of therapy while one 3 months. All showed an increase in IGF1 level compared to dGH, with values after the first month slightly higher in 4^th than in 2^nd day. The two patients with longer follow-up had IGF1 slightly above +2SDS for pubertal stage, remaining the same both at 3- and 6-month check-up. The third patient showed an IGF1 increase at +3SDS. Reducing GH dose by 15%, IGF1 dropped to the upper limits at 3-month control. All patients had a growth rate improvement >+1SDS with LAGH compared to dGH, regardless of puberty. Regarding naïve patients, one completed 6 LAGH therapy months, four 3 and one 1 month. All showed normal IGF1 for age, gender and pubertal stage at the first month, both in 2^nd and in 4^th day after injection. At 3-month control however, one of them had IGF1 value above +2SDS. Reducing GH dose by 15% brought IGF1 back to normal limits. All subjects showed an increase of growth rate ranging from +0.9 to +4.8 SDS.

Discussion: In our experience, naive subjects starting therapy seem to show a lower increase of IGF1 levels in comparison to switched patients; moreover, response to LAGH treatment is not the same in all patients. In our opinion, a frequent IGF1 dosing in the first months of Somatrogon therapy is recommended to customized the dosage.