SUN-132 Effectiveness of 6-Month Gnrha Formulations for Pubertal Suppression in Youth Assigned Male-At-Birth

Abstract Disclosure: N. Sun: None. M. Vargas Trujillo: Abbvie, Consultant. G. Chelvakumar: None. M. Marinkovic: None. Introduction: Pubertal suppression with gonadotropin-releasing hormone agonists (GnRHa) is a core component of gender-affirming care for transgender and non-binary (TG/NB) youth. In addition to monthly and three-monthly formulations, new long-acting GnRHa products, triptorelin and leuprolide acetate (Triptodur® and Fensolvi®) have been approved for use in central precocious puberty (CPP). Despite the increased use of these formulations for gender-affirming care, reports on the efficacy and safety of these formulations in TG/NB youth are sparse. Methods: IRB approval was obtained for a single-center retrospective chart review of TG/NB patients who received Triptodur® or Fensolvi®, assigned male at birth (AMAB) cohort is presented. Clinical and biochemical data during routine care over 12 months were collected, including random and stimulated LH, total testosterone (tT) levels, Tanner staging, and patients’ subjective reports of pubertal suppression. Results: Ten TG/NB treatment-naïve AMAB patients were included (Triptodur®-9/10, Fensolvi®-1/10). The mean age at initiation was 12.7 years (11.2 - 15.0) with baseline testicular volume of 11.6 ml (4 - 20). Mean baseline random LH was 1.77 mIU/mL (0.08 - 3.40) with mean total testosterone of 202.20 ng/mL (1 - 404). Average follow-up random LH levels at 3, 6, and 12-month assessments were 1.24 mIU/mL (0.27 - 3.40) with data from 5/10, 1.07 mIU/mL (0.11 - 3.29) data from 5/10, and 0.80 mIU/mL (0.22 - 1.78) data from 3/10, respectively. 3/10 had random or stimulated tT >50 ng/mL (51 - 304). Random tT was 10.80 ng/mL (7 - 22) with data from 5/10, 77.2 ng/mL (7 - 304) with data from 5/10, and 132.00 ng/mL (3 - 261) with data from 2/10, at 3, 6, and 12-month respectively. Seven patients had stimulated data: mean LH = 4.44 mIU/mL (0.60 - 9.70), with 3/7 (43%) with LH > 4.00 mIU/mL. All three were in an advanced pubertal stage (Tanner 5) at the time of treatment initiation (baseline testicular volume of 20 ml). Importantly, none showed evidence of further clinical progression while on treatment. In total, 7/10 (70%) had no clinical progression from baseline and 4/7 (57%) had testicular size reduction on treatment. 2/3 (67%) of those with clinical progression had biochemical data showing suppression at 12-months. Satisfactory pubertal suppression was documented in 9/10 (90%) patients. Conclusion: The majority of TG/NB patients AMAB in our study achieved pubertal suppression (biochemical, clinical, or both) with Triptodur® or Fensolvi® based on strict criteria used for CPP. Of those with subjective data, all reported adequate suppression. This study provides novel clinical and biochemical data of TG/NB patients AMAB on long-acting GnRHa formulations, Triptodur® and Fensolvi®, which can guide clinicians in their care. Presentation: Sunday, July 13, 2025