7152 CAHtalyst: Results From The Randomized, Double-Blind, Placebo-Controlled Period Of A Phase 3 Trial Of Crinecerfont, A Corticotropin-Releasing Factor Type 1 Receptor (CRF1) Antagonist, In Adults With Classic Congenital Adrenal Hyperplasia

Abstract Disclosure: R.J. Auchus: Consulting Fee; Self; Neurocrine Biosciences, Inc., Crinetics Pharmaceuticals, OMass Therapeutics, H Lundbeck A/S, Adrenas Therapeutics. Research Investigator; Self; Neurocrine Biosciences, Inc., Diurnal, Crinetics Pharmaceuticals, Spruce Biosciences. O. Hamidi: Advisory Board Member; Self; Corcept Therapeutics, Recordati Rare Diseases, Amryt Pharma, Neurocrine Biosciences, Inc., Xeris, Lantheus. R. Pivonello: Advisory Board Member; Self; Corcept Therapeutics, Recordati AG, Crinetics Pharmaceuticals, H. Lundbeck A/S. Research Investigator; Self; Corcept Therapeutics, Recordati AG, Strongbridge Biopharma, Neurocrine Biosciences, Inc. I. Bancos: Consulting Fee; Self; Corcept Therapeutics, Recordati Rare Diseases, HRA Pharmaceuticals, Neurocrine Biosciences, Inc., Diurnal, Spruce Biosciences, Sparrow Pharmaceuticals, Adrenas Therapeutics. Research Investigator; Self; Recordati Rare Diseases. G. Russo: Advisory Board Member; Self; Novartis Pharmaceuticals, Sandoz, Diurnal. Speaker; Self; Novartis Pharmaceuticals, Sandoz, Diurnal. S.F. Witchel: Research Investigator; Self; Neurocrine Biosciences, Inc. A.M. Isidori: Research Investigator; Self; Pfizer, Inc., Merck Serono, HRA Pharmaceuticals, Recordati AG, Corcept. P. Rodien: Consulting Fee; Self; Pfizer, Inc., Novo Nordisk, Lilly USA, LLC, Ipsen, HRA Pharmaceuticals, IBSA Pharma, Recordati Rare Diseases. U. Srirangalingam: Advisory Board Member; Self; Diurnal. Speaker; Self; Diurnal. F.W. Kiefer: Advisory Board Member; Self; AstraZeneca, Boehringer Ingelheim, Eli Lilly & Company, Novartis Pharmaceuticals, Novo Nordisk, Pfizer, Inc., Sanofi. Speaker; Self; AstraZeneca, Boehringer Ingelheim, Eli Lilly & Company, Novartis Pharmaceuticals, Novo Nordisk, Pfizer, Inc., Sanofi. H. Falhammar: Consulting Fee; Self; Diurnal, Roche Diagnostics, Neurocrine Biosciences, Inc., H Lundbeck A/S, Adrenas Therapeutics. D.P. Merke: Research Investigator; Self; Diurnal, Adrenas Therapeutics, Neurocrine Biosciences, Inc. N. Reisch: Consulting Fee; Self; Diurnal, Crinetics Pharmaceuticals, Neurocrine Biosciences, Inc., Spruce Biosciences, H Lundbeck A/S. J. Sturgeon: Employee; Self; Neurocrine Biosciences, Inc. E. Roberts: Employee; Self; Neurocrine Biosciences, Inc. V.H. Lin: Employee; Self; Neurocrine Biosciences, Inc. J.L. Chan: Employee; Self; Neurocrine Biosciences, Inc. R. Farber: Employee; Self; Neurocrine Biosciences, Inc.. Introduction: Classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD), a genetic disorder characterized by cortisol deficiency and excess adrenal androgens, typically requires management with supraphysiological glucocorticoid (GC) doses. Crinecerfont is a novel oral CRF1 antagonist that reduced elevated adrenocorticotropic hormone and adrenal androgens in patients with 21OHD in 14-day open-label Phase 2 studies. This Phase 3 study (CAHtalyst: NCT04490915) evaluated whether crinecerfont can reduce daily GC dose while maintaining androgen control in adults with 21OHD. Methods: Adults (≥18 years) with 21OHD, stable GC regimens at doses >13 mg/m2/d in hydrocortisone equivalents (HCe), and normal or elevated androstenedione (A4) were randomized (2:1) to crinecerfont 100 mg BID or placebo for 24 weeks. GC dosing was maintained stable for 4 weeks, followed by a planned GC down-titration over 8 weeks to achieve a GC dose of 8-10 mg/m2/d. GC doses were adjusted as needed during the last 12 weeks to maintain A4 control (≤120% of baseline or ≤upper limit of normal [ULN]) by week 24. Results: In the 182 randomized participants (51% male, mean age 31 years), demographics and baseline characteristics were similar between treatment arms (122 crinecerfont, 60 placebo). Mean GC dose at baseline was 17.6 mg/m2/d HCe (32 mg/d), with 58% on HC alone, 29% taking predniso[lo]ne, and 13% taking dexamethasone; mean pre-GC A4 (620 ng/dL) was elevated >2-3-fold the ULN. Over 95% of participants completed the double-blind treatment period. At week 24, the crinecerfont arm had a significantly greater percent reduction in GC dose while maintaining A4 control vs placebo (-27% vs -10%; least squares mean difference [LSMD]: -17%; p<0.0001) (primary endpoint). At week 4 (end of GC-stable period), a greater reduction in A4 prior to the morning GC dose was observed with crinecerfont vs placebo (LSMD: -345 ng/dL; p<0.0001) (key secondary endpoint). At week 24, a higher percentage of participants reached a protocol-defined physiological GC dose (≤11 mg/m2/d) while maintaining A4 control with crinecerfont (63% vs 18% for placebo; p<0.0001) (key secondary endpoint). The most common treatment-emergent adverse events (AEs) in the crinecerfont arm were fatigue (25% vs 15% for placebo), headache (16% vs 15%), and COVID-19 (14% vs 9%). There were few serious AEs (3% overall), with none assessed as related to the study drug. Conclusions: Crinecerfont, an oral CRF1 antagonist, represents a novel treatment option to improve androgen control for patients with 21OHD. In the largest interventional Phase 3 study conducted to date in adults with 21OHD, crinecerfont led to a significant reduction in A4 while GC dose was stable, enabling a significant percent reduction in GC dose while maintaining A4 control at 24 weeks. Crinecerfont was overall well tolerated. Presentation: 6/1/2024