52 Week Study + 24-Month Long-Term Extension of Safety, PK, & Efficacy of XYOSTED® for Testosterone Replacement in Male Adolescents With Hypogonadism

This is a 52-week open label single arm study + 24-Month long-term safety extension to investigate the effects of XYOSTED, as testosterone replacement therapy, on adolescent males with either primary or secondary hypogonadism. The study aims to determine the effectiveness of XYOSTED measured by continuation or induction of puberty in addition to XYOSTED dosage, safety and testosterone levels.

This is a Phase 3/4, open-label, multicenter study in approximately 100 males 12 to \< 18 years of age with primary or secondary hypogonadism (congenital or acquired). Each participant will be screened for eligibility within 28 days before receiving his first dose of study drug on Day 1. During the Screening period, each participant will have a full clinical examination with pubertal staging, including 2 separate serum total testosterone (TT) measurements obtained in the early morning, where the average (Cavg) will be considered baseline value. Each participant will be categorized as having primary or secondary hypogonadism prior to dosing on Day 1. Participants meeting all eligibility criteria will be assigned to a starting dose of XYOSTED based on their weight and Targeted Tanner Stage on Day 1. The Targeted Tanner Stage will be determined during Screening by an experienced pediatric endocrinologist. Participants will have dose adjustments during the study to achieve their Targeted Tanner Stage. Dose adjustments will be based on reviewing the TT concentration between doses (Cmid) by measuring serum TT 14 days after the administration of XYOSTED for participants receiving the Q4W schedule, 7 days after the administration of XYOSTED for participants who are on the Q2W schedule, and 4 days after administration of XYOSTED for participants on the Q1W schedule. Participants will be evaluated for further dose adjustments approximately every 3 months to achieve the desired targeted TT level. Following the 52-week primary study, participants may join a 24-month long-term safety extension study to continue the evaluation of XYOSTED in this population. Participants will return to the clinic at 6-month intervals for evaluation for clinical evaluations, and laboratory and pharmacokinetic assessments.