Two agents already hold accelerated approval in the same fibrosis stages. This is a live two-drug market, not one waiting for a second entrant.
The addressable population is defined by a fibrosis stage, which means it is defined by staging capacity. A large adult population has MASH with the fibrosis stages both agents are labelled for, sitting inside a far larger population with MASH and a larger one again with fatty liver disease. The label stops short of cirrhosis. Most of the eligible pool is undiagnosed or unstaged in primary care, so the reachable number is set by how many patients get through the diagnostic pathway rather than by how many have the disease.
That pathway is non-invasive and sequential: a blood-based index screens first, and indeterminate patients move to elastography for staging. A patient cannot be treated until they have been staged, so a MASH forecast is in practice a forecast of staging throughput in primary care and hepatology. Modelling from prevalence assumes diagnostic infrastructure that does not yet exist.
The competitive framing matters more here than in most categories. Both agents are in market now, on accelerated approval, in the same label-eligible population. Treating the second as a future entrant, and planning for a competitive event that has already occurred, is the expensive error. The defensible move is to secure preferred payer access and the fibrosis position in the first year.
AXLRx MASH reports size the staged, label-eligible pool with diagnostic throughput as the explicit lever, and read the two-agent contest as it stands today.
Rezdiffra and Wegovy now split the noncirrhotic MASH label. This is a Year 0 to Year 1 access and retention fight, not a pre-launch window.
The MASLD-to-MASH-to-F2-F3 funnel, NASH-CRN fibrosis staging, and the FIB-4-to-elastography diagnostic gap behind the 6.7M label-eligible pool.
Why Rezdiffra's $47,400 WAC lands inside ICER's value range, why the IRA reset hits semaglutide first, and how Part D routing shapes MASH access.
6.7 million Americans have F2-F3 MASH, but Rezdiffra has already reported 42,250+ patients on therapy and $311.3M in Q1 2026 revenue. This model triangulates population against real uptake, not a modeled guess.
Rezdiffra and Wegovy already hold the noncirrhotic F2-F3 label. The clearer opening for a new entrant is the compensated-cirrhosis boundary neither drug covers.
About 6.7 million US adults have MASH with F2-F3 fibrosis, which is the pool both approved agents are labelled for. That sits inside 14.9 million with MASH and 86.3 million with MASLD, and the F2-F3 group is projected to reach 11.7 million by 2050. The label stops at F2-F3: compensated cirrhosis at F4 is excluded. The commercial constraint is that most of the eligible pool is undiagnosed or unstaged in primary care, so the addressable number is set by staging capacity rather than by prevalence.
Non-invasively, in two steps. FIB-4 is the primary screen, with a score below 1.3 ruling out advanced fibrosis and above 2.67 ruling it in; indeterminate patients move to transient elastography or MR elastography for staging. Because the label is written around a fibrosis stage, a patient cannot be treated until they have been staged. Any MASH forecast is therefore a forecast of staging throughput in primary care and hepatology, and modelling it off prevalence assumes a diagnostic infrastructure that does not yet exist.
A present one, and treating it as a future one is the expensive error. Rezdiffra was approved in March 2024 and Wegovy in August 2025, and both hold accelerated approval in non-cirrhotic F2-F3 MASH. That makes this a live two-drug market now, not a market awaiting a second entrant. The defensible move is to lock preferred payer access and the fibrosis-regression position in the first year, rather than plan for a competitive event that has already happened.
They diverge on negotiation exposure. Both route to Medicare Part D. Rezdiffra appears on no CMS selected-drug list and, as a small molecule approved in March 2024, is not yet eligible for IRA negotiation; semaglutide was selected for IPAY 2027, so the near-term negotiated-price reset lands on the GLP-1 first. On value, ICER found resmetirom's net health benefit adequate on a narrow 8-7 Midwest CEPAC vote, with a value range of $39,600 to $50,100 a year, and the roughly $47,400 list price sits inside that range.
A sizing model that runs from the MASLD base down to the staged, label-eligible F2-F3 pool with FIB-4 and elastography throughput as the explicit levers; competitive intelligence on the two-agent market as it stands today; a payer read covering Part D routing, the differing IRA exposure of the two agents, and the ICER value range; and launch-readiness work on the first-year access contest. Each is scoped to your asset.