US MASH Launch Readiness

Rezdiffra and Wegovy already hold the noncirrhotic F2-F3 label and are in a retention fight, not a pre-emptive defense — the compensated-cirrhosis boundary neither drug covers is the real opening.

Two agents already hold FDA accelerated approval for the same noncirrhotic F2-F3 MASH label: Rezdiffra (resmetirom, Madrigal Pharmaceuticals, an oral THR-β agonist) approved March 14, 2024, and Wegovy (semaglutide 2.4mg, Novo Nordisk, a GLP-1 receptor agonist) approved August 15, 2025. A new entrant planning against a semaglutide threat still years away is planning against a market that no longer exists: semaglutide is already in-market, Rezdiffra already carries more than 42,250 treated patients and $311.3M in Q1 2026 net revenue (up 127% year over year), and the two incumbents are already competing for the diagnosed F2-F3 pool rather than defending an open field. A third F2-F3 entrant inherits an established formulary precedent, an established FIB-4-to-elastography diagnostic pathway, and two competitors already well into building physician and payer relationships.

The clearer opening is the label boundary both incumbents share: neither Rezdiffra nor Wegovy is indicated beyond noncirrhotic F2-F3 fibrosis, and compensated cirrhosis (F4) remains unaddressed. The FGF21 class, efruxifermin (Akero, running both a histology readout and a dedicated cirrhosis trial) and pegozafermin (89bio, with its own cirrhosis-specific trial), is positioning explicitly for this segment. A new entrant with a defensible F4 dataset does not need to win a head-to-head efficacy argument against resmetirom's 25.9 to 29.9% or semaglutide's 62.9% MASH-resolution rates, figures from separate trials (MAESTRO-NASH and ESSENCE respectively), not a head-to-head; it needs to be first to a label neither incumbent can currently claim.

Pricing precedent already exists for the F2-F3 segment and gives a new entrant, in F2-F3 or F4, a benchmark to price against. ICER found resmetirom's evidence adequate to demonstrate net health benefit versus lifestyle management (Midwest CEPAC panel vote 8-7) and set a value range of $39,600 to $50,100 per year; Rezdiffra's roughly $47,400 annual WAC sits inside that range, an unusually clean launch precedent. On IRA timing, the intuitive expectation, that a small molecule faces an earlier Medicare negotiation clock than a biologic, is directionally true (roughly 7 to 9 years post-approval for small molecules versus 11 to 13 for biologics, per KFF) but has run backwards in this market: semaglutide was selected for IRA negotiation in IPAY 2027, with the negotiated price applying across the Novo Nordisk franchise including Wegovy from January 1, 2027, while resmetirom appears on no CMS selected-drug list through IPAY 2028. A new entrant should plan its own IRA exposure against this same asymmetric timeline, not the sequence intuition would predict.