Eighty milligrams of atumelnant once daily cut morning androstenedione by 67 percent at week 12, and it did so while participants simultaneously stepped down their glucocorticoid doses to physiologically normal levels. That combination, sustained androgen suppression alongside genuine steroid reduction, is what makes the full Cohort 4 data from Crinetics’ Phase 2 TouCAHn trial, presented Saturday at ENDO 2026, worth serious attention. Seven of eight participants who completed 12 weeks of treatment achieved a daily glucocorticoid dose below 11 mg/m²/day hydrocortisone equivalents, a threshold the Endocrine Society defines as physiologic for adults, who typically require 15 to 25 mg per day under current standard of care. Getting patients below that ceiling without allowing androgens to rebound has been the persistent frustration of CAH management for decades.
The mechanistic logic matters here. Atumelnant is a selective antagonist at the melanocortin type 2 receptor on the adrenal gland, blocking excess ACTH directly rather than working upstream through the hypothalamic-pituitary axis. Cohort 4’s design tested whether morning dosing could replicate the androgen reductions seen in earlier cohorts that used evening administration. It did. Mean reductions in 11-OHA4 and 11-KT reached 64 percent and 56 percent respectively at week 12, and those reductions held even as glucocorticoid doses were cut stepwise, independent of androstenedione levels. The steroid reduction was not contingent on biomarker performance; it was protocol-driven and still succeeded. No treatment-related severe or serious adverse events were recorded across any dose level or disease severity group.
The competitive landscape for classic CAH has shifted recently. Crinecerfont (Crenessity) received FDA approval in December 2024 as an adjunctive treatment to glucocorticoid replacement in adults and pediatric patients four years and older. Crinecerfont targets CRF1 receptors upstream; atumelnant targets MC2R downstream. Whether physicians and payers will differentiate on mechanism, dosing simplicity, or depth of androgen suppression is not yet clear, but Crinetics is advancing atumelnant into Phase 3 with the CALM-CAH trial already enrolling adults and a pediatric arm in development. The Phase 1b/2a data in ACTH-dependent Cushing’s syndrome, also presented at ENDO 2026, add a second potential indication: at 40 mg once daily over 10 days, urinary free cortisol normalized in three of six participants.
The single number to track from Phase 3 is the proportion of adults who sustain physiologic glucocorticoid dosing at 24 weeks. That endpoint defined crinecerfont’s Phase 3 success and will serve as the de facto comparison point for atumelnant when CALM-CAH reads out, regardless of whether Crinetics frames it that way.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
