SAT286 Effect of Tildacerfont On Gonadotropins And Testicular Steroidogenesis In Men With Classic 21-hydroxylase Deficiency

Disclosure: R. Charlton: Employee; Self; Spruce Biosciences, Inc. A. Khattab: Consulting Fee; Self; Antares Pharma, Inc. R.J. Auchus: Grant Recipient; Self; Spruce Biosciences, Inc. Research Investigator; Self; Spruce Biosciences, Inc. Impaired testicular function is a common comorbidity of classic 21-hydroxylase deficiency (21OHD). Testicular adrenal rest tumors (TART) can disrupt testicular architecture and cause primary hypogonadism. Both supraphysiologic glucocorticoid doses and adrenal-derived androgens and estrogens can suppress gonadotropins and cause secondary hypogonadism. We conducted a post-hoc analysis of gonadal axis function in men with 21OHD participating in SPR001-201 and SPR001-202, two phase 2 studies of tildacerfont, a once-daily oral corticotrophin-releasing factor receptor 1 (CRFR1) antagonist, designed to reduce ACTH and adrenal steroid production, including androstenedione (A4). Study 201 included 3 cohorts: Cohort A, 5 men who received tildacerfont in a 6-week dose escalation - 2 weeks at 200 mg QD, 2 weeks at 600 mg QD, and 2 weeks at 1000 mg QD without washout between doses; Cohort B, 1 man who received tildacerfont for 2 weeks at 200 mg BID; and Cohort C, 4 men who received tildacerfont for 2 weeks at 100 mg BID. Study 202 included 4 men who received tildacerfont 400 mg QD for 12 weeks. Participants continued their previously prescribed glucocorticoid ± mineralocorticoid replacement without dose adjustments. Geometric means were used to describe hormone levels due to the small participant numbers. Mean and median ages were 46/32y in Study 201 and 32/35y in Study 202 (range 18-54 in both studies). All participants reported race as white except one who identified as white and Asian. Four reported ethnicity as Hispanic or Latino. At baseline, testosterone (T) levels were normal except for four 201 participants that had T 1, indicating a predominantly adrenal origin of T. In Study 201, mean T levels increased in Study 201 from 375.5 ng/dL to 390.5 ng/dL at week 2 (n=9), 485.4 ng/dL at week 4 (n=4) and 420.7 ng/dL at week 6 (n=4). In Study 202, mean T levels were 448.4 ng/dL at baseline and 412.0 ng/dL at week 12. Mean LH levels increased in Study 201 from 0.68 IU/L to 1.59 IU/L at week 2 (n=10), 1.62 IU/L at week 4 (n=5) and 0.85 IU/L at week 6 (n=4) (normal 1.8-8.6IU/L). In Study 202, mean LH levels increased from