SUN-131 Pubertal Suppression for Youth Assigned Female At Birth: Experience With 6-Month Formulations

Abstract Disclosure: N. Sun: None. M. Vargas Trujillo: Abbvie, Consultant. G. Chelvakumar: None. M. Marinkovic: None. Introduction: Gonadotropin-releasing hormone agonists (GnRHa) are an integral part of gender-affirming care for transgender and non-binary (TG/NB) youth. Within the last decade, new long-acting GnRHa formulations, triptorelin and leuprolide acetate (Triptodur® and Fensolvi®) were approved for use in central precocious puberty (CPP). Despite the increased use of these formulations for gender-affirming care and the significant differences between the CPP and TG/NB populations, studies assessing the outcomes of pubertal suppression in TG/NB youth are lacking. Methods: IRB approval was obtained for a single-center retrospective chart review of TG/NB patients who received Triptodur® or Fensolvi®. Data presented here are from the assigned female at birth (AFAB) cohort. Clinical and biochemical data were collected and reviewed over a 12-month period. Random and stimulated luteinizing hormone (LH) and estradiol levels were assessed as well as Tanner staging, menstrual bleeding, and patient’s subjective report of pubertal progression at clinical follow-ups. Results: Twenty-one TG/NB AFAB patients were included (Triptodur®-18/21, Fensolvi®-3/21). 16/21 (76%) were treatment naïve. The mean age at time of Triptodur® or Fensolvi® initiation was 12.4 years (10.0 - 15.5) with average baseline breast Tanner stage of 3.9 (1 - 5). Mean baseline random LH was 0.57 mIU/mL (0.02 - 34.25) with mean random estradiol of 26.47 pg/mL (2.00 - 101.00). Average follow-up random LH levels at 3, 6, and 12-month assessment were 0.50 mIU/mL (0.05 - 2.11) with data from 13/21, 0.42 mIU/mL (0.11 - 0.80) with data from 11/21, and 1.31 mIU/mL (0.18 - 5.30) with data from 5/21, respectively. Nine patients had stimulated data, assessed at 6 or 12-months post-treatment initiation. The mean stimulated LH was 1.94 mIU/mL (0.71 - 6.31). 2/9 (22%) had LH levels > 4.00 mIU/mL but neither had pubertal progression clinically. Of those with Tanner staging assessments at baseline and at least once during the 12-month study, 15/17 (88%) had no progression from baseline. Notably, those with documented clinical progression showed adequate biochemical suppression. 10/21 (48%) had documented menstrual bleeding on treatment with 8/10 (80%) occurring within the 1st month of GnRHa initiation. Conclusion: Extrapolating suppression criteria from the CPP literature, the majority of TG/NB patients AFAB achieved or maintained pubertal suppression (biochemical and/or clinical) with Triptodur® or Fensolvi®. To our knowledge, our study is the first one to provide clinical and biochemical data of TG/NB patients AFAB on long-acting GnRHa formulations, Triptodur® and Fensolvi®, which can serve as a guide to clinicians. Presentation: Sunday, July 13, 2025