Miricorilant

Miricorilant is Corcept Therapeutics' selective glucocorticoid receptor modulator in Phase 2b MONARCH, testing whether blocking cortisol signaling in the liver reduces fat buildup in nonalcoholic steatohepatitis (NASH/MASH). The mechanistic bet is that chronically elevated glucocorticoid tone drives hepatic lipogenesis, so a selective antagonist should shrink liver fat without the systemic side effects of full GR blockade. Primary readout is percent change in liver fat by MRI-PDFF in a 175-patient study across two cohorts [1]. The NASH space now has one approved therapy (Madrigal's Rezdiffra) plus a newly published Phase 3 win for semaglutide in histology (ESSENCE, NEJM 2025) [12], so miricorilant needs a liver-fat reduction that either matches those benchmarks or offers real differentiation. Corcept's broader franchise runs on cortisol biology (Korlym in Cushing's, relacorilant in oncology and Cushing's), making miricorilant an extension of platform expertise into a much larger indication.

Miricorilant is a novel compound never approved for any indication. It is currently Phase 2b in NASH/MASLD via MONARCH (NCT06108219), which is active but no longer recruiting after enrolling ~175 patients across two cohorts [1]. No FDA breakthrough, fast track, or orphan designations for the NASH program have been publicly disclosed. Corcept's supporting Phase 1 work is broad: a hepatic impairment PK study (NCT05553470) [2], a food effect and bioavailability study (NCT07240116) [3], an ongoing PK and safety study (NCT07553663) [4], and a mechanistic MASLD study measuring fasting hepatic lipogenesis (NCT06947304) [5]. This suite of Phase 1 activity, plus the newly published PK and metabolism paper [6], suggests Corcept is building the dossier needed to move directly into a Phase 3 program once MONARCH reads out. Corcept guided on the Q2 2026 earnings call (July 29, 2026) that MONARCH topline data are expected later in 2026, which points to a Q4 2026 readout window [11]. Regulatory posture will hinge on how the effect size compares against Rezdiffra (resmetirom), which set the current bar by winning accelerated approval in 2024 on MASH resolution and fibrosis improvement [7], and now against semaglutide's Phase 3 histological win [12].

Cortisol is the body's main stress hormone. When it binds the glucocorticoid receptor (GR, encoded by NR3C1), the receptor moves into the nucleus and switches on genes that raise blood sugar, break down muscle, and push fat storage into the liver. That is why people on long-term steroids like prednisone develop fatty liver, weight gain, and insulin resistance. The NASH hypothesis is that even without pharmacologic steroids, subtle chronic overactivation of hepatic GR signaling drives the lipid accumulation and inflammation seen in the disease. Miricorilant is designed to blunt that signal selectively without shutting down cortisol biology system-wide. Full GR blockade causes adrenal crisis, so the point of a selective modulator is to antagonize the lipogenic gene program without triggering counter-regulatory surges from the HPA (hypothalamic-pituitary-adrenal) axis, the brain-to-adrenal feedback loop that controls cortisol production. Proof of concept for the metabolic hypothesis came from Corcept's earlier study in healthy subjects, where miricorilant blunted olanzapine-induced weight gain [8], showing the drug can move a metabolic phenotype in humans. The published PK and disposition profile is now characterized in a 2026 J Clin Pharmacol paper [6]. Whether the mechanism translates to real NASH pathology reversal, not just a lower liver-fat percentage on MRI, is the open question. GR modulation has strong biological logic and preclinical support but no approved product yet in metabolic liver disease. Rezdiffra hits thyroid hormone receptor beta [7], so a positive miricorilant readout would establish a genuinely first-in-class approach in this indication and open the door to combination positioning with the currently approved and emerging classes.

MONARCH (NCT06108219) is a Phase 2b study, active but not recruiting, in about 175 adults with NASH/MASH. Primary endpoint is the percent relative change from baseline in liver fat content measured by MRI-PDFF (magnetic resonance imaging proton density fat fraction), a well-validated non-invasive imaging biomarker for hepatic steatosis [1]. The design is two cohorts with clinically meaningful differences per Corcept's AASLD 2025 design abstract [13]. Cohort A enrolls approximately 82 biopsy-confirmed MASH patients (NAS greater than or equal to 4 with fibrosis stage F2 or F3), randomized 2:1 to 100 mg miricorilant or placebo twice weekly for 48 weeks, with histological secondary endpoints including MASH resolution and fibrosis improvement. Cohort B enrolls approximately 93 patients with milder disease (F1 fibrosis or presumed MASH not meeting Cohort A criteria), randomized 2:1 to a dose escalation regimen of 100 mg twice weekly for 6 weeks followed by 200 mg twice weekly for 18 weeks (24 weeks total) or placebo. The Cohort A biopsy secondaries are the operationally important piece: they give Corcept its own histology-based read on Phase 3 readiness rather than relying on the MRI-PDFF-to-histology inference alone. MRI-PDFF as the primary is a Phase 2 standard, and it is not sufficient for FDA approval on its own. NASH accelerated approval requires biopsy-confirmed MASH resolution without worsening fibrosis, or fibrosis improvement without worsening MASH, and Phase 3 requires histology [7]. MONARCH is therefore a signal-generation study, not a registrational one, though a clean Cohort A histology signal would materially de-risk the Phase 3 design.

Our model estimates a 5% chance this drug is eventually approved. It starts from the historical base rate for Phase 2 drugs in this area (about 23%), then adjusts using ten facts about the trial and sponsor. What moves the number most: it is helped by more secondary endpoints than usual; it is held back by heavier-than-usual blinding, the sponsor's thin or weak approval record, and weak or limited earlier-phase results. The other facts land near average for this stage, so they leave the estimate roughly where the base rate put it.

Efficacy risk is the primary threat, and the competitive bar just went up. Semaglutide's ESSENCE Phase 3 interim (800 patients, 72 weeks, biopsy-defined MASH with F2 or F3 fibrosis) reported 62.9% MASH resolution without worsening fibrosis versus 34.1% for placebo (delta 28.7 points), and 36.8% fibrosis improvement without worsening MASH versus 22.4% for placebo (delta 14.4 points), published in NEJM April 30, 2025 [12]. Semaglutide is now not just a weight-loss story in NASH but a drug with a positive Phase 3 histology readout. That is the new commercial bar. MRI-PDFF is also easier to move than biopsy-confirmed fibrosis, so a positive MONARCH MRI-PDFF result does not guarantee a positive Phase 3. NASH history is littered with drugs that reduced liver fat and then failed to improve fibrosis or MASH resolution in histology-based trials (selonsertib, cenicriviroc, elafibranor's original path). The MRI-PDFF-to-histology gap has cost the field billions. Miricorilant needs enough magnitude in fat reduction, and ideally a Cohort A histology signal, to make the Phase 3 bet credible. Safety risk is specific to GR biology. Full GR blockade causes adrenal insufficiency, hypokalemia (abnormally low blood potassium, which can cause muscle weakness and cardiac arrhythmia), and hypertension. Selective modulators are designed to avoid this, but any signal of HPA axis disruption, cortisol counter-regulation, or metabolic side effects in a chronic-dosing, largely healthy-appearing NASH population would be a problem [6, 11]. Regulators will scrutinize this closely. Commercial risk is the tightest constraint. Rezdiffra has first-mover advantage and is already generating revenue for Madrigal [7]. GLP-1s (semaglutide, tirzepatide) now have prescribing momentum from obesity plus histological NASH validation [12]. FGF21 programs at Akero (efruxifermin) and 89bio (pegozafermin) are showing strong fibrosis improvement in mid- and late-stage trials, and Boehringer's survodutide (GLP-1/glucagon dual agonist) has posted its own Phase 2 NASH histology signal. For a first-in-class oral GR modulator dosed twice weekly, miricorilant's positioning question is real: an oral, non-injectable option could be preferred for some patients relative to weekly subcutaneous semaglutide, but only if the efficacy is in the same conversation. If the effect size is materially smaller, oral convenience alone is unlikely to carry the launch. Execution risk is moderate. Corcept has run late-stage trials in Cushing's and oncology but not in a large, heterogeneous metabolic population.

Worth watching, not urgent. Miricorilant is a mechanistically interesting bet on hepatic cortisol biology in a very crowded NASH field. Corcept knows GR chemistry better than anyone, and MONARCH will test whether that expertise translates outside their comfort zone of cortisol-driven diseases like Cushing's syndrome. The specific signals to watch in the topline are: (1) the MRI-PDFF result from MONARCH's primary endpoint (a greater-than-30% relative reduction from baseline is the historical Phase 2 marker that predicts histological improvement, and would be competitive with the Rezdiffra Phase 2 benchmark; anything under 20% and the program stalls); (2) Cohort A histology secondaries, since a clean MASH resolution or fibrosis improvement signal would materially de-risk Phase 3 and help differentiate against semaglutide's ESSENCE numbers of 62.9% MASH resolution and 36.8% fibrosis improvement [12]; and (3) any HPA axis safety signal across both cohorts, since even a hint of cortisol counter-regulation would tank the profile. Timing: Corcept guided on the Q2 2026 earnings call to a topline readout later in 2026, pointing to Q4 2026 [11]. Financially, Corcept generated $256M in Q2 2026 revenue on Korlym plus its newly launched product, with 2026 guidance raised to $1.1 to $1.2B and a relacorilant PDUFA on December 17, 2026 [11]. That cash and pipeline depth mean miricorilant is upside optionality, not a make-or-break bet. If MONARCH hits on both the MRI-PDFF primary and Cohort A histology secondaries, it becomes a serious pipeline asset and a rare first-in-class NASH mechanism with an oral, twice-weekly profile that could complement or compete with injectable GLP-1s.