This Biotech Has $700 Million in Revenue and Another Commercial Opportunity Approaching

Biotech investors love an FDA date. This one is eight days away, and it will get plenty of attention. But there is another catalyst coming behind it that could matter far more.

The company is already expected to generate $680 million to $700 million this year, with revenue growing more than 40%. For a biotech this size, that commercial base gives the pipeline a very different starting point.

Three products, 44% revenue growth, and the Morgan Stanley conference

Mirum Pharmaceuticals (NASDAQ: MIRM) presented at a major healthcare conference earlier this week and laid out the clearest picture yet of where the business stands. CEO Chris Peetz confirmed full-year revenue guidance of $680M to $700M across three approved medicines.

That is not projected revenue. That is what the business is on track to deliver this year, with an 82% gross margin sitting underneath it.

The revenue machine powering all of this is LIVMARLI, approved for cholestatic pruritus in Alagille syndrome and progressive familial intrahepatic cholestasis (PFIC).

The surprise in recent quarters has been adult PFIC: thousands of adult patients previously labeled with “idiopathic cholestasis” are being correctly diagnosed as PFIC and started on LIVMARLI.

That is an expanding patient pool nobody expected, and management is now growing the field team specifically to accelerate it.

CHOLBAM and CTEXLI round out the commercial portfolio and have been growing quietly under a dedicated genetics and metabolic diseases team.

What the next eight weeks look like

The schedule from here is dense. The FDA PDUFA decision on zilurgisertib in FOP lands in eight days. Phase 3 AZURE-1 brelovitug data in hepatitis delta is expected later this month. Two more Phase 3 readouts are expected next quarter.

This is a company with four clinical shots on goal landing in rapid succession, backed by an already operating commercial business.

That combination, a growing revenue base absorbing the R&D cost while multiple high-value catalysts approach, is what separates this from a pure-play binary biotech bet.

The FOP decision: real, but crowded

Zilurgisertib targets fibrodysplasia ossificans progressiva, a devastating rare disease where soft tissue gradually converts into bone. Roughly 300 patients in the U.S. have a confirmed diagnosis. 

Mirum licensed global rights from Incyte earlier this year for an upfront payment and is prepared to launch in the fourth quarter if approved.

Here is the honest context: FOP is no longer an empty market. Ipsen’s Sohonos was approved in 2023. Regeneron’s Pasatru received approval in August. A zilurgisertib approval would make it the third option in a patient population of about 300. 

That is a meaningful commercial launch and extends Mirum’s rare disease infrastructure into medical genetics, but it is not the blockbuster opportunity it might look like at headline level.

The clinical story is nuanced too. The PROGRESS trial’s primary endpoint, the count of new bone formations, missed conventional statistical significance. The volume of new bone growth, a separate measure, showed a much more compelling reduction versus placebo.

Leerink said the volume result may be sufficient for approval. Approval is plausible, but it is not a slam dunk, and the commercial payoff in a three-way competitive market is inherently capped.

Brelovitug and the HDV opportunity nobody is pricing in

This is where the setup gets interesting.

Hepatitis delta is a co-infection that requires hepatitis B to exist, but when it hits, it is far more aggressive. Patients progress to cirrhosis, liver failure, and cancer at a dramatically faster rate than hepatitis B alone. 

Management estimates about 15,000 diagnosed patients in the insured U.S. population, with a total prevalence closer to 40,000, and that number is likely to grow as testing improves.

There is no FDA-approved therapy for chronic HDV in the United States. None. Gilead’s bulevirtide is European only.

Brelovitug is a fully human antibody targeting HDV. Phase 2b data showed 100% virologic response at 24 weeks with the weekly dosing regimen, with a substantial portion of patients also achieving liver enzyme normalization. 

Phase 3 AZURE-1 data is expected this month. If the data holds, Mirum is potentially looking at a first-to-U.S.-market position in a disease category with no competition. That is the opportunity that does not show up in the current price.

Revenue that funds the pipeline without constant dilution

Mirum's biggest structural advantage over most biotechs at this stage is that the commercial business is paying the bills.

LIVMARLI has been growing for several years and shows no signs of slowing. Adult PFIC is a newer growth driver that was not in the original model.

The bile acid portfolio is contributing steadily. Together, those three products generate enough gross profit to fund the entire clinical pipeline without forcing the company to issue equity at the worst possible moments.

That changes what binary risk looks like here. A Phase 3 failure in brelovitug is painful, but it does not create an existential cash crisis. The LIVMARLI base business keeps running. Volixibat and the other programs keep advancing. You are not starting over from zero.

This is the profile that gets underappreciated in biotech coverage.

When people see “biotech,” they price in maximum binary risk. When the underlying commercial business is already generating close to $700 million in revenue at 82% gross margins, that framework overstates the downside.

The beta tells the story

Mirum’s five-year beta sits at 0.49. For a biotech with multiple programs in Phase 3, that is strikingly low. It is the fingerprint of a stock where the commercial base is absorbing the volatility that the pipeline would otherwise create.

As more catalysts resolve and the pipeline either adds or subtracts from that base, the volatility story will shift, but for now the low beta reflects the stabilizing effect of a real operating business.

Not cheap, but not pricing in the optionality either

At roughly 9.5 times this year’s product revenue guidance midpoint, the stock is not deeply discounted.

The Seeking Alpha analysis pegs a $100 price target at current levels, essentially saying the base business is fairly valued and the pipeline is close to zero. That feels like an underpriced view of what happens if brelovitug delivers.

A clean Phase 3 in HDV transforms Mirum from a cholestatic liver disease company with some pipeline assets into a company with two commercial platforms: a liver disease franchise centered on LIVMARLI plus brelovitug, and a rare genetics franchise centered on the bile acids plus potentially zilurgisertib.

The re-rating from one platform to two has historically been significant for commercial-stage rare disease names.

Peers with a single approved drug and a clean Phase 3 win in an orphan indication with zero competition have re-rated meaningfully in the weeks after data. The multiple expands because the total addressable market math changes overnight.

You are not paying for that outcome yet.

Revenue growth of 44% looks explosive. About half of it is the adult PFIC discovery.

LIVMARLI was originally positioned as a pediatric drug. The surprise adult PFIC patient population is real and durable, but it represents a pulled-forward wave of new diagnoses that will normalize at some point.

The company is actively expanding the field team to sustain the discovery rate, but this is not the kind of growth engine that compounds indefinitely at the same pace.

The honest baseline for LIVMARLI’s normalized growth rate is probably in the high-teens to low-twenties range once the adult PFIC discovery wave matures. That is still excellent growth for a rare disease product. It is just not 44%.

Watch quarterly new-patient start data and the adult PFIC contribution trend. If that contribution starts to plateau, headline growth will decelerate, which could temporarily weigh on sentiment even if the underlying business is healthy.

Brelovitug could miss. The Phase 2b data was genuinely encouraging with 100% virologic response at 24 weeks. Phase 3 is a larger population with harder statistical thresholds and more sites. 

Biotech Phase 3 failures from strong Phase 2b data happen regularly. A brelovitug miss takes the HDV optionality to zero and removes the most compelling catalyst for re-rating.

The FOP approval might not happen, or might disappoint commercially. The PROGRESS trial’s primary endpoint did not reach conventional statistical significance. The FDA may ask for more data or narrow the label. 

Even with approval, the commercial payoff in a three-way competitive market with roughly 300 diagnosed U.S. patients is inherently limited.

Volixibat in PSC has regulatory uncertainty. Management was surprised by the FDA’s Phase 3 request after believing the Phase 2 VISTAS data was sufficient for an NDA. That kind of regulatory misstep creates headline risk even if the underlying data is strong. 

The FDA’s questions may or may not be resolvable with existing data. Until the NDA is accepted, PSC is a risk, not a catalyst.

The balance sheet carries accumulated losses. Mirum has negative equity on the balance sheet from prior years of losses. 

The company expects to reach GAAP profitability around 2028. Until then, headline losses will periodically spook generalist investors who are not familiar with how rare disease commercial ramps work.

The setup here is specific.

You have a rare disease biotech that already has a real business, not a pre-revenue story, with a Phase 3 readout imminent in a disease category with zero U.S. competition. The FDA decision in eight days is real but overweighted in coverage relative to what brelovitug actually means if it delivers.

If AZURE-1 reads out positively this month, the stock re-rates on new math: two commercial platforms, an expanding rare disease infrastructure, and a liver team that can eventually support three approved products. That is a different company than what the current multiple is pricing.

If brelovitug fails, you own the LIVMARLI commercial business at a fair-to-slightly-rich multiple with pipeline optionality in volixibat and the FOP franchise. That is not a zero, but it is also not a bargain.

Position this for what brelovitug can do, not what the FOP decision will do. Size it accordingly for binary risk. The FOP outcome is a near-term noise event either way. The HDV data is the one that actually changes the long-term story.

Looking to buy? Wait for the FOP decision noise to settle before sizing up. The brelovitug readout is the real event, and it is still upcoming. A starter position now before both catalysts makes sense; a full position into binary risk does not.

Already own it? Hold through both catalysts. The FOP decision in eight days is the near-term event, but watch brelovitug data closely when it arrives. That is your signal for whether to add or trim.

Main risk to respect: Brelovitug failing Phase 3 removes the most compelling re-rating catalyst and leaves you owning a fairly-priced commercial business with PSC regulatory uncertainty and a crowded FOP market. Size the position for that scenario.

That's our coverage for today; thanks for reading! Reply to this email with feedback or any stocks you want me to check out.

Best Regards,
—Noah Zelvis
Undervalued Edge