Mirum Pharmaceuticals at Stifel 2025: Optimism in Rare Disease Space

On Tuesday, 11 November 2025, Mirum Pharmaceuticals (NASDAQ:MIRM) participated in the Stifel 2025 Healthcare Conference, presenting a robust performance and optimistic outlook. The company reported its first positive net income, driven by strong sales of its key product, LIVMARLI, in rare disease treatments. Despite challenges in market size estimation, Mirum remains confident in its growth trajectory.

Key Takeaways

• Mirum Pharmaceuticals reported $133 million in Q3 revenue, achieving positive net income for the first time.
• LIVMARLI, used for treating Alagille syndrome and PFIC, is projected as a billion-dollar brand.
• Genetic testing is expanding the PFIC market, contributing significantly to LIVMARLI's growth.
• Mirum anticipates pivotal data readouts for Volixibat in the next 18 months, targeting PSC and PBC.
• The company is focused on unmet needs in rare cholestatic liver diseases, positioning for continued growth.

Financial Results

• Q3 2023 Revenue:

- $133 million across all programs.

• Net Income:

- Achieved positive net income for the first time.

• LIVMARLI Projections:

- Expected to be a billion-dollar brand.

- Alagille syndrome accounts for about 40% of this potential.

- PFIC and expand indications each contribute roughly 30%.

Operational Updates

• LIVMARLI in Alagille Syndrome:

- Approximately 50% market penetration in the US.

- High capture rate of newly diagnosed patients.

• LIVMARLI Tablet Formulation:

- Approved earlier this year, with high conversion rates among eligible patients.

- Expected to improve compliance and persistence.

• PFIC Launch:

- Exceeded expectations, driven by new patient identification through genetic testing.

• Expand Study:

- Targets ultra-rare cholestatic pruritus, with an estimated 500 U.S. patients.

• Volixibat Program:

- Data for PSC expected in Q2 next year.

- PBC enrollment to complete next year.

- LIVMARLI label expansion study on track for enrollment completion.

Future Outlook

• LIVMARLI Growth:

- Alagille syndrome to drive steady growth.

- Continued patient accumulation expected.

• Volixibat Potential:

- Seen as a potential blockbuster for PSC and PBC.

- PSC market estimated at 30,000 patients in the U.S., with initial focus on pruritus.

• PSC Trial Expectations:

- Confidence in active dose effectiveness.

Q&A Highlights

• LIVMARLI in PFIC:

- Genetic testing is crucial for market expansion.

• LIVMARLI Tablet Uptake:

- Positive reception among older patients, aiding compliance.

• Competitive Dynamics:

- Approaching 50% market share for PFIC in the US.

• Volixibat in PSC:

- Focus on pruritus as a key outcome.

Readers are encouraged to refer to the full transcript for a detailed account of the conference call.

Full transcript - Stifel 2025 Healthcare Conference:

James Condoles, Analyst, Stifel: Great. Thanks everyone for being here. I'm James Condoles, one of the analysts here at Stifel, and it's a pleasure to kick off the conference with Mirum Pharmaceuticals. We have Chris Peetz, CEO here. Everyone, feel free to jump in as you have questions. I have a bunch, but maybe we can just start it off with kind of a quick overview of another great quarter and anything you want to highlight from AASLD this past weekend.

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah, thanks, James, for having us. Just to cover a couple of little background about Mirum for those who aren't familiar, we're a commercial rare disease-focused company. Third quarter, we just announced we had $133 million of top-line revenue across our programs, three approved products spanning different ultra-rare genetic settings, and a pipeline that's really busy right now. We're heading into three potentially pivotal readouts over the next 18 months, kind of layering those out. Q2 next year, we expect top-line data from our PSC program with Volixibat. We're enrolling a second Volixibat study in PBC that we expect to complete enrollment next year. Then a label expansion study for LIVMARLI that's on track to complete enrollment next year as well. Busy across the board. Also, in the third quarter, a bit of a milestone. We actually hit positive net income for the first time.

Focus mostly on growth and top line, but just great to see the business model that can be quite efficient in these rare settings playing out. You asked also about AASLD. Just coming off of being at that meeting over the weekend in Washington, D.C., and a lot of energy there. It was well-attended and for our team, it's a lot of opportunity to interact with potential prescribers and the investigators working on our programs. A few data sets that I'd call out from us that were presented there. One was follow-up analysis of Volixibat in PBC. The Vantage study of Volixibat in PBC had an interim analysis last year. This was a follow-up analysis looking at fatigue and sleep scores. One of the most important symptoms right up there with pruritus in this setting.

Just great data to share out of that interim analysis showing a strong impact on fatigue and sleep with Volixibat. We also had some case studies of Livdelzi in PSC, kind of showing a proof of concept of IBAT in the PSC setting where clear response on pruritus across those compassionate use case studies. The other theme of the meeting was genetic testing. I'm sure that'll come up as we go through some more conversations about our programs, but kind of growing adoption of genetic testing for hard-to-diagnose patients in the adult hepatology setting.

James Condoles, Analyst, Stifel: Great. Great. Maybe we can dive into some of the dynamics with LIVMARLI. You guys have kind of continued to beat expectations. Maybe we can start with Alagille syndrome and just kind of begin to level set kind of where you think kind of IBAT penetration is today, kind of where you think that can go from here, and kind of what's kind of necessary to kind of drive continued growth.

Chris Peetz, CEO, Mirum Pharmaceuticals: Right. Livmarli and Alagille syndrome, I mean, this was our first indication. Just the profile of Livmarli in this setting, it drives really high response on pruritus and serum bile acid reduction. That's what the original data set was. What that means from a patient standpoint is it's really high impact and results in a great profile, right? Patients that respond tend to stay on therapy long term because of the benefit that they're seeing. That plays out in kind of the top line over time where it's a great product profile. Today, we think we're probably about 50% penetrated in the US in terms of patients that have had exposure to Livmarli. That quarter to quarter, we continue to see growing into that prevalent untreated group. Also underneath that, there's new diagnoses every year.

We have a pretty high capture rate of those newly diagnosed patients. The business, taking a step back and thinking about the profile of Alagille syndrome for LIVMARLI over time, is a steady underlying growth driver. Expect it to continue to accumulate and add patients on therapy. As they're doing well, they stay with the drug long term.

James Condoles, Analyst, Stifel: Yeah. Yeah, makes sense. I guess for those, are they all IBAT naive patients? Are they these kind of older patients that are out there? Who else is kind of within the prevalent pool out there? Kind of how do you kind of capture them, you think?

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah, in general, we think they're IBAT naive. That's what all of our data suggests. There's competing agent Bylvay that's also approved in this setting where we think we're over 80% share overall, but probably getting most of the new patient starts in that setting. From a commercialization standpoint, we kind of talk about our competition often being engagement with care and intent to treat and recognize some of the symptomatic burden. That's what we are kind of deploying against for those untreated patients is building awareness of symptomatic burden and helping physicians and patients recognize some of the symptoms that they're dealing with and awareness of a treatment option for it.

James Condoles, Analyst, Stifel: Yeah, makes sense. I guess you have this tablet formulation for Livmarli as well. For some of those kind of prevalent patients who are maybe older, is that something that's been a tailwind in terms of kind of further penetrating kind of that more maybe adult kind of patient population?

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah, so the tablet of LIVMARLI was approved earlier this year. The rollout's been great. Reception to it from the older patients, and it tends to be kind of early teenage years is where there's a strong preference to have a tablet instead of the liquid formulation that is great for the younger kids. Patients tend to age out of it. We've seen a very high rate of conversion for those that are at that age where they're eligible for the tablet. It's probably early days to say that we're seeing that impact in the top line yet because what we think the tablet means for patients is better long-term compliance and persistence, right? There was the one-off patient that was older that wanted to have a solid dose form that may have switched. Now we have one tablet per dose option.

That's a really compelling convenience factor to keep patients on drug long term. Kind of how this plays out now is the older patients that are new to drug, they're selecting the tablet form almost universally. Some of those, the teenagers or adults that are on therapy have, for the most part, already switched over in these first months since the approval.

James Condoles, Analyst, Stifel: Yep. Yep, makes sense. Maybe kind of one question on pricing. I know historically you've shown some data of patients that have gone kind of weight-based dose adjustments over time. Could you maybe kind of talk about that dynamic and how it's kind of continuing to play out in the real world and how important that is as part of a kind of growth prospect of LIVMARLI in terms of how much of a pricing tailwind there may be over time?

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah, I'd describe it as a gradual growth driver over time. In any given quarter, we're not seeing big step ups in the average consumption at all. Some of that because as we're going, we're adding some of these very young, newly diagnosed patients that when they start out, they're at a very low dose. The average tends to kind of slowly creep up over time. It's there and it'll continue to help support growth. Quarter to quarter, it's a smaller contribution than the new patient starts.

James Condoles, Analyst, Stifel: Yep. Yep, that makes sense. I guess do you see at some point there being, I don't know, I guess like an inflection where you have such a large sort of patient base where those newer infant diagnoses and infants coming on drug are less overall piece of the overall pool of patients, where pricing might really swing at some point? Is that something that you guys think about in terms of what pricing may do over time?

Chris Peetz, CEO, Mirum Pharmaceuticals: I mean, it's just something that's a natural part of the profile of a product like this. It's just by the numbers as you get more and more patients on, those dose adjustments start to play a bigger role. We do see it continuing to add as we go forward.

James Condoles, Analyst, Stifel: Yep. Okay, great. Meanwhile, I mean, I think PFIC is off to a, seems like a great start as well. Maybe above some people's expectations. It'd be great to kind of just understand and kind of level set there, kind of how you guys think that's been going and kind of what's been driving that kind of initial uptake and success.

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah, the PFIC launch for LIVMARLI has gone really well. It beat our expectations, frankly, and continues to. A few different factors have played into that. One is just the profile of LIVMARLI data from the pivotal study in PFIC, really strong response rate. We also saw placebo-controlled improvements in bilirubin and growth. This overall data profile is just really exciting for the prescribers. We started out with a really strong product profile that's compelling for physicians caring for PFIC patients. There has been another dynamic that has really started to emerge more this year since the label expansion last year. It has been patient identification. The growth we're seeing from PFIC is, for the most part, new patient identification and bringing IBAT naive patients either to a diagnosis or to treatment.

A lot of it from expanding awareness of genetic testing, in particular as you get into the adult clinics where historically PFIC has been thought of as a pediatric ultra-rare genetic pediatric disorder. We're finding that there's across most adult centers, if you go in and have a conversation about some of their patients, there is a pool of patients that are under or misdiagnosed, maybe labeled as idiopathic cholestasis. As you get genetic testing into some of those settings, they're finding that there's PFIC genetics behind what's been kind of a misunderstood cholestatic and often quite symptomatic and progressive condition.

James Condoles, Analyst, Stifel: Yeah. Yeah, no, that's really interesting. It sounds like that genetic testing is only kind of continuing to ramp up, as you mentioned, from this weekend at the conference. I guess as you kind of look at all these dynamics and kind of how you're finding these patients, I know historically you thought PFIC might be a third of Alagilles. Curious where you kind of think about that today in terms of on a relative basis, like how big of a market it might be.

Chris Peetz, CEO, Mirum Pharmaceuticals: For PFIC, it's really challenging to put a number on it. I mean, that's the short answer. We don't know what denominator we're working with. It's quite promising in terms of what the early signs are in terms of being able to find a diagnosis for some of these patients that have been a struggle for the adult hepatologist to care for. Really early on in terms of adoption of that genetic testing, it's a small circle of more of the KOLs that are probably doing it today. I think there's a lot to work with there. I don't have an answer for you. It's definitely bigger than the one-third of Alagille syndrome that we originally thought. We will see how far we can take it and help get more patients to a diagnosis and to care.

James Condoles, Analyst, Stifel: Yep. Yep, makes sense. I'm sure it's also hard to say kind of where IBAT inhibitor penetration is within PFIC, obviously, if we don't exactly know kind of how big it is. Maybe it'd be helpful to kind of just understand how you think about kind of like the competitive dynamics with Bylvay and kind of how that's been playing out so far in terms of the real world.

Chris Peetz, CEO, Mirum Pharmaceuticals: We think it's playing out well for us. I think we're probably approaching half of the share for PFIC in the U.S. That's been by expanding the total market. As I said, it's not a really high switch dynamic or market that we see in either of these indications. We think the real path to growth is to help get more patients to a diagnosis and to care. One thing I can do to kind of help size things a little bit on our view of it is we've been talking about our long-term view of LIVMARLI. We see it as being at least a billion-dollar brand over time. The biggest piece of that is Alagille syndrome. We expect Alagille syndrome to be, call it roughly 40% of that billion plus.

The PFIC and the expand indication, probably each of those roughly 30% of that peak number that we talk about.

James Condoles, Analyst, Stifel: Yeah, that's really helpful. Maybe we can talk about expand because I think that kind of remains relatively underappreciated in terms of how big that may be. Maybe it'd be helpful to just kind of set the stage on that trial, kind of when we may see data, and kind of your overall expectations.

Chris Peetz, CEO, Mirum Pharmaceuticals: The expand study is looking at Livdelzi versus placebo in ultra-rare settings of cholestatic pruritus. It is a protocol that the inclusion criteria are defined by exclusion. It is a long tail of different causes of cholestasis, patients with elevated bile acids and pruritus that excludes the bigger indications: Alagille, PFIC, PSC, PBC, cholestasis of pregnancy explicitly excluded from that. There is a lot of biliary atresia in there. That is probably the biggest piece of it. Then a long list of smaller other indications. The idea and inspiration for this indication actually came from pretty high demand of compassionate use for patients that fit this profile that did not have a protocol, that did not have access to commercial drug. Because of such a high volume of compassionate use requests, we got into a conversation with FDA about putting a protocol together around it.

Had a dialogue to make this into essentially a registrational basket study to cover all of these ultra-rare settings. Each one on its own is pretty small. In aggregate, from some of our tallying, there are at least 500 patients in the U.S. that fit this profile. As we get deeper into it, we see more demand and more of these patients than I think we originally had thought when we launched the program.

James Condoles, Analyst, Stifel: Yep, makes sense. Maybe one last question there. I know Ipsen's running a biliary atresia study. Their design's a little bit different in terms of the endpoint. They're running an outcome study. Just curious your perspectives on kind of their trial and kind of them as a potential competitor in this kind of broader tail of cholestatic diseases.

Chris Peetz, CEO, Mirum Pharmaceuticals: What I can do, I can speak to some of our experience because we ran a prior study in biliary atresia with LIVMARLI kind of looking at that very young, more acute setting in biliary atresia. It's a really tough setting. The study that we ran was a six-month study looking at bilirubin and a list of other endpoints, including outcomes in the six months immediately after a Kasai procedure. Biliary atresia, the first step for standard of care and treatment is to have a surgical reestablishment of bile flow from the liver into the GI tract. That's called the Kasai procedure. For a lot of patients, it's really effective at getting bile flow established. Without that, this disease uniformly leads to liver failure and is fatal.

What we saw in that study is that Kasai procedure, that's really what was determining outcomes in that really acute period. Unfortunately, did not see further improvement on bilirubin and outcomes from what was already being provided by the Kasai procedure. What we think is happening is over time, those that have a successful Kasai that have this quite pronounced drop in bilirubin and establish the bile flow, they do well in the first years, but over time, they can have kind of a slowly, much slower progressing cholestasis that could be caused by the surgical scarring or still incomplete biliary tree or other factors from the original disease that creates this longer progressing cholestasis and eventually pruritus too.

Kind of going back to what's worked for this class for an outcome for an approval, focusing on that itch outcome is something that we know we can move. It's relevant for patients. That's kind of what's led us to putting those patients into the expand study.

James Condoles, Analyst, Stifel: Great. No, makes sense. I do want to make sure we get to Volixibat. Any other questions on LIVMARLI or kind of the base business from anyone? Great. Yeah, I mean, it sounds like everything's going well there and there's a lot of room for growth on the base business. Volixibat, obviously, kind of the first readout will be 2Q next year for PSC, as you mentioned. Obviously, you guys have so much data kind of across etiologies with this mechanism. It's been highly successful. You had the PSC positive interim, the PBC interim. I guess as you kind of think about PSC next year, what is the risk, if any, as you kind of think about that trial and just your overall confidence in it playing out as you guys are hoping for?

Chris Peetz, CEO, Mirum Pharmaceuticals: We feel that we have, from what we know about Volixibat, we have an active dose. We know that IBATs are really impactful and relevant in cholestatic pruritus. The interim analysis of the Vistus PSC study also builds confidence. I can kind of maybe take a step back and go through some of the data that supports each of those points. One, for Volixibat, when we started the program, we did pretty extensive dose ranging work because the dosing for IBATs is pretty easy to get misunderstood if you're looking at PD markers like cholesterol lowering and bile acids. Because in a cholestatic setting, as you dose higher and dose through what looks like a FX ceiling, you can actually see much deeper response on bile acids and itch, for example.

We did early work to make sure that we were at the higher end of the dose range. In the Vistus study, we actually still explored two doses in the first part of that. We had a lower dose, which we believed would be highly active, and then a higher dose to make sure that we did not miss kind of a further deepening of the response based on some of that early dose ranging work. In the Vistus study, there was a blinded interim analysis that had instruction for the DMC on an algorithm to make a dose selection. If there was no efficacy advantage of the higher dose, that dose would be dropped and you would automatically roll into the second portion of the study. There is an opportunity for it to upsize if it was close. None of that happened.

The DMC said the interim analysis was completed in a success and it automatically rolled into the confirmatory portion at that 20 milligram BID dose. From that interim, we know we have an active dose and excited about getting to that final readout. The one just kind of risk of kind of jumping back and forth between the programs, we also kind of looked to the PBC interim analysis for Volixibat for evidence on what we expect to see in PSC. The PBC study had an open interim analysis that we conducted last year, announced and have presented some of the data that I mentioned on pruritus and now fatigue and sleep, seeing a really high response rate and a great profile out of that PBC interim analysis at the same dose that we're taking forward in PSC.

James Condoles, Analyst, Stifel: Yep. Yep. Makes sense. There's a lot of data supporting that. I think one thing that's come up when we've talked to doctors is these PSC patients do have bowel disease sometimes. Obviously, by nature of the IBAT mechanism, there's some initial sort of GI AEs. Is there any risk in these PSC patients kind of specifically? I'm just kind of curious your overall comfort with the AE profile there and kind of like what gets you confident.

Chris Peetz, CEO, Mirum Pharmaceuticals: Yep. Across the study conduct, no issues coming out. Really not from blinded data and treatment experience from Mirum Pharmaceuticals. Not seeing any difference in profile in these PSC patients compared to other settings. In IBAT in general, kind of as well known, the mechanism drives some treatment initiation, in particular, mild to moderate diarrhea. That's on target mechanistic part of the bile acid clearing. That is how the drug is getting its effect. In the Volixibat PSC study, as you'd expect in this population, there's a high rate of patients that have background IBD. We're not seeing higher rates or any worse AE profile from that blinded data.

James Condoles, Analyst, Stifel: Yep. Okay. Great. Maybe just jumping to kind of the commercial picture. On paper, PSC is obviously a very large rare disease. How are you thinking about sort of how many of these patients are truly addressable? Kind of what the kind of TAM over time can look like and just overall the positioning of this drug as kind of the first of its type in this disease?

Chris Peetz, CEO, Mirum Pharmaceuticals: PSC in the U.S., call it roughly 30,000 patients is what the overall prevalence is estimated to be at. Our label and our launch is going to be in pruritus due to PSC. We think that's probably two-thirds or 60% of that population. It's interesting when you go out and have conversations about it, though, on how there probably is not adequate discussion of it with physicians. This really comes out in some of the conversations we've had with our market research and interactions with different sites. There's a pretty stark divide in between what the physician thinks the pruritus burden is versus, for example, the nursing team or the patients, where physicians tend to report it as less common because they're not asking about it.

The nursing teams and the patients will talk about it as high as 90% of the patients having pruritus that they're dealing with. That is one of the focuses we have for market development and commercializing these medicines, helping support those conversations that physicians could be having with their patients on finding out what is symptomatic burden. Do they have pruritus? Now I have a drug. Now I have a tool that I can use to help you. Where without that, it really hasn't been central to a lot of patient conversations.

James Condoles, Analyst, Stifel: Yep. Yep. Makes sense. Yeah. I guess kind of like in that context, I know you've talked about Volixibat potentially being another sort of blockbuster opportunity overall across PSC and PBC. Do you think one of them is a bigger opportunity? How do you think about the relative PSC versus PBC in terms of what the opportunity may present?

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah. They're both really attractive indications and kind of for slightly different reasons in terms of their profile. For PSC, no other approved therapies. Using itch as an outcome here for approval is novel. That's opening the door to actually having a new treatment for PSC. What I'm excited about is how our team has put this program together to be able to actually have a drug labeled in PSC. Competitively, that's a huge advantage, obviously. To have Volixibat potentially be the first and only approved in PSC without clear endpoints to bring other competing agents forward. In PBC, it's slightly different. There are other programs. There are recently approved drugs in the second-line setting. Another IBAT inhibitor that is filed for approval for itch kind of in a first and second-line setting. There's more of a competitive dynamic there, but a much larger setting.

As many as 100,000 PBC patients in the U.S. While there'll be more segmentation and a competitive dynamic, there's far more patients. Both high-impact indications for the top line for us.

James Condoles, Analyst, Stifel: Yep. Makes sense. I think with PBC, as you mentioned, there's so much data here kind of supporting this mechanism. You talked about the interim for PBC, which was open label. I think the one question we've, looking at GSK, which you mentioned there's another IBAT inhibitor in PBC, there was kind of a large placebo response. Just curious what you think of those data and how that kind of compares to what you're assuming in your powering assumptions on PBC.

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah. For our powering assumptions, a couple of things to key in on. One is just overall effect size. That comes back to some of the dosing work that we did, where we think we're at the maximal effective dose, a really highly active dose based on that 2.4-point placebo-adjusted difference we saw in the interim analysis, 3.7 change from baseline. That's a really deep response for itch in this setting. We assumed a pretty high variability rate in the PSC study, for example, similar to the PBC study. We powered it based on a 1.75 placebo-adjusted difference and a standard deviation of 3. All the data that we've seen in these data sets, that standard deviation of 3 is really conservative. We think that that's going to add power. There are also some study conduct steps you can do operationally to help control that placebo response.

There's always going to be some there in an itch study, in a patient-reported outcome study like this. The best you can do is operationally put in steps to control it around training on how to fill out the survey, a long screening run-in period to help normalize some of those itch scores and try and weed out some of the placebo response early. What we saw in the interim data for Vantage really showed that that's working in these studies.

James Condoles, Analyst, Stifel: Yeah. Great. Yeah. No, looking forward to the start of the Volixibat story next year. Okay. Maybe in just the last minute, real quick, wanted to get your perspectives on you have a Fragile X program. We're still kind of waiting for data from Zynerba Pharmaceuticals, a competitor with a similar mechanism. Just curious how you think about, one, how important those data are to kind of your confidence in the program, and then going forward when we may see data from your program and kind of what a win looks like there.

Chris Peetz, CEO, Mirum Pharmaceuticals: Yeah. We're excited to see that readout. I mean, what I'd say, though, the proof of concept that got us excited about jumping in this program really comes back to the phase two data they've already reported, where you see a really striking improvement in these cognitive scores. And for 3379, what led us to take on this program is that there's an opportunity for a much better CNS exposure with this drug. So there's higher brain penetrance. And we think that could lead to a much better profile. And that's why we're running this dose ranging study to really prove out that potential dosing advantage and CNS exposure advantage.

James Condoles, Analyst, Stifel: Awesome. We're just up on time. Thanks so much, Chris, for being here. Thanks everyone for joining.

Chris Peetz, CEO, Mirum Pharmaceuticals: Thanks for the time and the interest in Mirum.

James Condoles, Analyst, Stifel: Of course.

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