SUN-416 Crinecerfont Improves Clinical Outcomes in Adults With Classic Congenital Adrenal Hyperplasia: 1-Year Results From the CAHtalyst™ Adult Study

Abstract Disclosure: R.J. Auchus: Has been involved in contracted research with companies such as Neurocrine Biosciences/Neurocrine UK, LTD, Spruce Biosciences, Corcept Therapeutics, Crinetics Pharmaceuticals, Recordati Rare Diseases, Adrenas Therapeutics, and Mineralys Pharmaceuticals, Served as consultant for organizations like Quest Diagnostics, Corcept Therapeutics, Xeris Pharmaceuticals, Crinetics Pharmaceuticals, Novo Nordisk, Neurocrine Biosciences/Neurocrine UK, LTD, Recordati Rare Diseases, H Lundbeck A/S, Sparrow Pharmaceuticals, Astellas Pharmaceuticals, and Acerand Therapeutics. O. Hamidi: Advisory board member for Neurocrine Biosciences, Corcept Therapeutics, Recordati Rare Diseases, Crinetics Pharmaceuticals, Inc, Camurus, Xeris Pharmaceuticals, Inc, Educational speaking engagement with Recordati Rare Diseases. I. Bancos: None. K. Saag: Recieved grants or contracts from Amgen, Arthrosi, Horizon, LG Pharma, Radius, and Olatec, Received consulting fees from Amgen, Anthrosi, Atom Bioscience, Horizon, LG Pharma, Angitia, and Gruenthal. H. Falhammar: None. U. Srirangalingam: Consulting fees from Crinetics Pharmaceuticals, Diurnal Ltd and H Lundbeck A/S. M. Calanchini: None. E. Jen: Full-time employee of Neurocrine Biosciences, Inc. V.H. Lin: Full-time employee of Neurocrine Biosciences, Inc. J. Sturgeon: Full-time employee of Neurocrine Biosciences, Inc. J.L. Chan: Full-time employee of Neurocrine Biosciences, Inc. Background: Crinecerfont, a corticotropin releasing factor type 1 receptor (CRF1) antagonist, is a first-in-class medication that is FDA-approved for adjunctive treatment to glucocorticoid (GC) replacement to control androgens in patients with classic congenital adrenal hyperplasia (CAH). In the Phase 3 CAHtalyst™ Adult study (NCT04490915), crinecerfont (100 mg BID) significantly reduced adrenal androgens, enabling substantial GC dose reductions from Day 1 baseline (BL) at the end of double-blind placebo-controlled (DBPC) treatment at Week 24, with a least-squares (LS) mean percent change of -27.3% vs. -10.3% for placebo (LS mean difference [LSMD] -17.0%, P<0.0001). At the end of open-label (OL) treatment at Month 12, mean percent decreases from BL in GC dose were -24.6% in participants who continued on crinecerfont (CFT/CFT) and -29.7% in those who switched from placebo (PBO/CFT). Objective: To evaluate clinical outcomes in adults with CAH who received up to 1 year of crinecerfont, in the context of substantial GC dose reductions. Methods: Outcomes related to excess adrenocorticotropic hormone (ACTH)/androgens (e.g., hirsutism in female participants) and GC exposure (e.g., body mass index [BMI], insulin resistance, hyperlipidemia) were analyzed at the end of DBPC treatment (Week 24) and the end of OL treatment (Month 12). DBPC outcomes with P-values are presented as LS mean changes with LSMD. Results: In female participants, mean hirsutism visual analog scale scores (out of 0 [no symptoms] to 100 [very severe symptoms]) were 40.6 (crinecerfont) and 37.4 (placebo) at BL. Changes from BL at end of DBPC (Week 24) and OL (Month 12) were: Week 24 (-9.8 for crinecerfont [n=58] vs -2.8 placebo [n=27], LSMD -7.0, P=0.1564); Month 12 (-11.5 CFT/CFT [n=56], -12.9 PBO/CFT [n=27]). Mean BMI at BL was 30.1 kg/m2 (crinecerfont) and 29.0 kg/m2 (placebo). Changes from BL were: at Week 24 (-0.4 vs. -0.02 for crinecerfont [n=118] vs. placebo [n=57], LSMD -0.40, P=0.1068); at Month 12 (-0.8 CFT/CFT [n=114], -0.4 PBO/CFT [n=56]). Mean homeostatic model assessment of insulin resistance values were high at BL (crinecerfont 3.2, placebo 3.0). Changes from BL were: at Week 24 (-0.6 vs. -0.4 for crinecerfont [n=61] vs placebo [n=29], LSMD -0.29, P=0.3454); at Month 12 (-0.5 CFT/CFT [n=107], -0.9 PBO/CFT [n=54]). Mean values for cholesterol (total, LDL, and HDL) and triglycerides were within normal range or near optimal at BL and remained stable. Conclusion: Adults with CAH who received up to 1 year of crinecerfont continued to show improvements in BMI and insulin resistance, as expected with lower GC doses. Moreover, despite substantial GC dose reductions, hirsutism in female participants improved with crinecerfont. Given the known adverse effects of ACTH/androgen excess and chronic supraphysiologic GC exposure, these results represent a promising therapeutic advancement in CAH. Presentation: Sunday, July 13, 2025