Mirum Pharmaceuticals Inc

NASDAQ:MIRM

Earnings Call Analysis

Mirum's Impressive Growth and Strong Pipeline

Mirum Pharmaceuticals reported an outstanding quarter with net product revenue reaching $77.8 million, a 139% increase from last year. Key highlights include regulatory achievements and the initiation of the EXPAND study, targeting cholestatic pruritus across various conditions. The VISTAS and VANTAGE studies for volixibat showed promising interim results, suggesting significant potential for treating chronic liver diseases. With robust financials and strategic expansions, Mirum is on track to meet its full-year revenue guidance of $310 million to $320 million. The company continues to push forward with its strategic priorities, aiming to enhance its commercial success and advance its diverse product pipeline【4:0†source】.

Strong Growth in Product Sales

In the second quarter of 2024, Mirum Pharmaceuticals reported impressive total net product sales of $77.8 million, a remarkable 139% increase compared to $32.5 million in the same quarter the previous year. This surge is predominantly attributed to the strong demand for its flagship products, LIVMARLI, CHENODAL, and CHOLBAM. Specifically, LIVMARLI's sales reached $47.2 million globally, reflecting a 45% year-over-year growth driven by the expansion of its indications for Alagille syndrome and progressive familial intrahepatic cholestasis (PFIC). As the company progresses, the management is optimistic about achieving its full-year revenue guidance of $310 million to $320 million.

Regulatory Advances and Label Expansions

Mirum achieved several key regulatory milestones during this quarter. LIVMARLI is now approved for the treatment of cholestatic pruritus and PFIC in the U.S., with a notable label update allowing use for patients aged 12 months and older. This opens avenues for treating a wider range of patients as PFIC is commonly diagnosed in early childhood. Furthermore, the company has initiated the EXPAND study, targeting cholestatic pruritus across various rare diseases, potentially benefiting over 500 patients in the U.S.

Promising Clinical Trials for Volixibat

The company reported positive interim results from its clinical studies involving volixibat, aimed at addressing cholestatic pruritus in primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC). Both studies, VISTAS and VANTAGE, exceeded prespecified efficacy thresholds, indicating statistical significance in reducing itch intensity. During the VANTAGE study, participants experienced approximately a 2.3-point improvement over placebo. These findings bolster volixibat's potential as a groundbreaking therapy for these conditions, particularly as they currently lack approved treatments.

Financial Position and Operating Expenses

Mirum's financial health stands robust, with cash and cash equivalents amounting to $295.4 million, despite a decrease of $7.4 million from the prior quarter. The company reported a net loss of $24.6 million, or $0.52 per share, while operating expenses totaled $102 million for the quarter. This includes significant investments in research and development ($32.7 million) and selling, general, and administrative expenses ($49.2 million). Importantly, $17.7 million of these costs were noncash charges, indicating a disciplined management of cash resources.

Outlook and Future Growth Strategies

As Mirum looks ahead, the management is focused on advancing its strategic priorities, including the expansion of its established medicines, progressing with volixibat, and exploring new pipeline opportunities. With a keen focus on growth in the rare disease market, particularly in pediatric populations, there's an expectation that the company's innovative drug developments will capture a significant share of unmet medical needs. Mirum’s leadership demonstrates confidence in its ability to navigate regulatory pathways and expand product indications effectively.

Challenges and Cautious Optimism

While the company is optimistic about its growth trajectory, it also faces challenges in the reimbursement landscape for its PFIC treatment. A significant proportion of new patients for PFIC treatment are expected to utilize free drug shipments this year, which could moderate revenue contributions initially. However, there is confidence among management that these dynamics will normalize, leading to enhanced revenue flow in 2025 as the patient base stabilizes and scales.

Earnings Call Transcript 2024-Q2

[Operator]

Good afternoon, everyone, and welcome to the Mirum Pharmaceuticals reports second quarter 2024 financial results and provides business update. My name is Carla, and I will be coordinating your call today. [Operator Instructions] I will now hand you over to Andrew McKibben, Vice President of Investor Relations and Finance, to begin. Andrew, please go ahead.

[Andrew McKibben, executive]

Thanks, Carla, and good afternoon, everyone. I'd like to welcome you to Mirum Pharmaceuticals Second Quarter 2024 Conference Call. I'm joined today by our CEO, Chris Peetz; our President and Chief Operating Officer, Peter Radovich; our Chief Medical Officer, Joanne Quan; and Eric Bjerkholt, our Chief Financial Officer.

Earlier today, Mirum issued a news release announcing the company's results for the second quarter of 2024. Copies of this news release and SEC filings can be found in the Investors section of our website.

Before we start, I'd like to remind you that during the course of this conference call, we will be making certain forward-looking statements based on management's current expectations, including statements regarding Mirum's programs and market opportunities for its approved medicines and product candidates. These statements represent our judgment as of today and inherently involve risks and uncertainties that may cause actual results to differ materially from the results discussed. We are under no duty to update these statements. Please refer to the risk factors in our latest Form 10-Q and subsequent SEC filings for more information.

With that said, I'd like to turn the call over to Chris. Chris?

[Christopher Peetz, executive]

Thanks, Andrew, and good afternoon to everyone. I'm excited to share with you the outstanding progress we've made in this quarter with our commercial medicines and pipeline. It's been a strong quarter across the board with continued growth, important regulatory achievements and positive volixibat interim results.

On the commercial side, adoption of our medicines continues to grow with total net product sales of $77.8 million across LIVMARLI, CHENODAL and CHOLBAM, representing a 139% increase from the second quarter of last year. Building on the strength, we've also achieved important regulatory milestones for our commercial medicines. We submitted our NDA for chenodiol in CTX, which, if approved, will allow us to take additional steps to reach this underdiagnosed population and provide an opportunity for orphan exclusivity.

For LIVMARLI, I'm very happy to say that we are now approved for cholestatic pruritus and PFIC in the U.S. and for the treatment of PFIC in Europe. And we recently announced the U.S. label update to reduce that age to 12 months and older. We're looking forward to bringing LIVMARLI to PFIC patients given the impressive clinical impact that we've seen in this population.

I'm also excited to announce the initiation of another potentially label-enabling study for LIVMARLI in cholestatic pruritus.I'll let Joanne speak to some of the details, but in short, cholestatic pruritus is not limited to Alagille syndrome, PFIC, PSC and PBC. We see multiple additional rare disease settings where patients develop cholestasis and experience significant pruritus.

Supported by high interest from physicians and compelling response case studies, we are launching the EXPAND study to bring LIVMARLI to patient communities that would otherwise be challenging to study individually. Collectively, across these settings, we estimate there are at least 500 patients in the U.S. alone that would be eligible for this indication.

And finally, we took an important step towards advancing volixibat towards potentially pivotal data with the positive interim readouts of the VISTAS PSC and VANTAGE PBC studies. Our VISTAS PSC study exceeded the prespecified efficacy threshold and is continuing enrollment to the full study readout. With no approved therapies in PSC, we are positioned to bring the first medicine to this patient community. The interim results of the VANTAGE study in PBC were also very encouraging, with a statistically significant improvement in pruritus in a patient population that spans first and second-line PBC. I'm happy to say that enrollment is progressing well for both programs.

It was a pack second quarter for Mirum. So to dive into the details, I'll turn the call over to Peter to start with our commercial business. Peter?

[Peter Radovich, executive]

Thanks, Chris. I'm pleased to report another strong quarter across all 3 commercial products, and we continue to track well towards our full-year revenue guidance of $310 million to $320 million.

Starting with LIVMARLI, total global net product sales grew to $47.2 million this quarter, which represents a 45% increase compared to the same quarter last year. In the U.S., sales were $35.5 million, while international sales were $11.7 million. Growth continues to be driven by new Alagille syndrome patient additions comprised of both prevalent patients and newly diagnosed, a dynamic we expect to persist going forward.

We also are beginning to see prescriptions for PFIC patients, and our recent label expansion to include patients 12 months and older provides incremental opportunity given that PFIC is generally diagnosed when children are young. Internationally, LIVMARLI demand growth was strong, and I'm pleased to say that we achieved a favorable outcome in our price negotiations with Germany.

Stemming from this, we saw some price reference impact on international sales in Q2. We expect this to run its course in the next quarter or 2. We were also very happy with the European Commission's recent endorsement of LIVMARLI for PFIC 3 months and older, which highlights a significant benefit of LIVMARLI for these patients.

Lastly, we saw nice demand growth from CHOLBAM and CHENODAL in the second quarter, where we recognized net product sales of $30.5 million.

Overall, I'm thrilled with the continued strong commercial performance in the first half of the year and proud of the Mirum team's continued execution. We are on a solid path to achieve our full-year guidance of $310 million to $320 million and continued growth.

And with that, I'll turn it over to Joanne. Joanne?

[Joanne M. Quan, executive]

Thanks, Peter. We had an exceptional quarter, highlighted by the impressive interim analyses for the VISTAS study in PSC and the VANTAGE study in PBC. I'll give a quick recap of the results.

Starting with the VISTAS study in PSC. We set a prespecified threshold for continuation based on both efficacy and safety. The blinded interim analysis met this threshold and our independent data review committee recommended proceeding with a 20 milligram BID dose and that the study continue without any changes. The blinded analysis confirms a meaningful treatment effect and also allows us to include these patients in the total patient number for the final analysis. We're happy with how the study is enrolling and anticipate completing enrollment in the second half of 2025.

Moving on to the VANTAGE study in PBC. We're thrilled with the interim results. Both doses of volixibat showed a substantial and statistically significant reduction in itch and approximately 2.3-point improvement over placebo. Based on this, the VANTAGE study will also continue with the 20 milligram BID dose, consistent with the VISTAS study. The results support volixibat's potential as an important advance for patients suffering from cholestatic pruritus. We also observed reductions in serum bile acids and improvements across multiple dimensions on the PBC-40, most notably fatigue. We look to complete enrollment in 2026 for this larger step.

Overall, these results are significant for PBC patients, suggesting that volixibat has the potential to set a new standard in addressing the burden of cholestasis. We've already ramped up enrollment efforts and are targeting up to 100 total sites.

Shifting gears a bit, I would like to talk about the new Phase III EXPAND study. Mirum has received a number of requests for compassionate use of LIVMARLI in patients with cholestatic pruritus across a variety of ultra-rare indications. We believe these conditions share a common path genetic like cholestasis, leading to elevated serum bile acids, which results in persistent pruritus.

Based on the good responses we've seen in some individuals receiving compassionate use, we are optimistic that LIVMARLI can play a significant role in the treatment of pruritus for these patients. EXPAND is a randomized, double-blind, placebo-controlled study evaluating LIVMARLI for treatment of pruritus over 12 months. EXPAND study will enroll patients with cholestatic pruritus associated with a range of conditions such as biliary atresia, secondary sclerosing cholangitis and other less common conditions. Our target is to enroll approximately 45 patients, and we expect to complete enrollment in 2026.

I look forward to providing further updates on VISTAS, VANTAGE and EXPAND in the coming quarters.

I'll now turn it over to Eric to discuss our financial results. Eric?

[Eric Bjerkholt, executive]

Thanks, Joanne. Earlier today, we issued a press release that included financial results for the second quarter, which I'll briefly summarize.

Net product revenue in the second quarter 2024 was $77.8 million compared to net product revenues of $32.5 million in the second quarter last year.

Total operating expense for the quarter ended June 30 were $102 million, which includes R&D expense of $32.7 million, SG&A expense of $49.2 million and cost of sales of $20.2 million. The total operating expense for the quarter included approximately $17.7 million of noncash charges, of which $5.7 million was included in cost of sales.

For the quarter ended June 30, '24, net loss was $24.6 million or $0.52 per share.

Our cash, cash equivalents and investments was $295.4 million as of June 30, '24, a reduction of $7.4 million from the end of the prior quarter. Cash used in the second quarter included the payment of a $10 million milestone to Takeda upon FDA approval of the LIVMARLI PFIC indication.

With our robust commercial performance and continued financial discipline, we are in an excellent position to support the development of our pipeline and growth of our commercial business.

Now I'll turn the call back over to Chris for final comments.

[Christopher Peetz, executive]

Thanks, Eric. It's been a great first half of the year. I'm proud of the Mirum team and our strong execution. We are well positioned to continue to advance our 4 strategic priorities: to grow our commercial business, expand the indications of our approved medicines, advance volixibat in adult cholestasis and continue to look for opportunities to grow the pipeline.

With that, operator, please open the call for questions.

[Operator]

[Operator Instructions] And our first question comes from Dae Gon Ha from Stifel.

[Dae Gon Ha, analyst]

Congrats on the progress. Two from us, one commercial and one clinical. I guess, starting with commercial. As we look at the approval label across Alagille and PFIC in the U.S., it's kind of a palindrome between LIVMARLI and Bylvay. So I was hoping if you could maybe comment a little bit on what you've learned from perhaps Bylvay's experience analog that you can implement to broaden LIVMARLI's reach within the PFIC segment before further label expansion can come down the pipe?

And then in terms of clinical side, Joanne, enrollment progressing favorably sounds great. Is there any initiative for you to perhaps accelerate enrollment into VISTAS and VANTAGE trials?

[Christopher Peetz, executive]

On the -- first, kind of a comment on the labeling and label expansion we've seen for LIVMARLI, and can circle back for any follow-up questions. But what I think you're asking is just how the sequencing has gone for LIVMARLI. It's played out really well. I think we're in a position kind of very strong leadership in Europe, where we're the only products approved for both indications. In the U.S., we're now -- we see it as very equal footing, where we're now approved for both indications. Initial reception has been quite strong. And the data for LIVMARLI in both indications, we think tells a really compelling story for prescribers, and that's what we're seeing play out in the real world.

So in terms of that kind of label sequencing, I think it's largely played out and to the favor of LIVMARLI. And I'll let Joanne maybe comment on the enrollment strategies.

[Joanne M. Quan, executive]

Like I said, we're happy with how the enrollment is going. As you've noticed, we've been very excited by the interim analysis results in the PBC and the PSC and we share that with our investigators. And they share the excitement on that and really are seeing the potential impact that this has as a medicine for both patient populations. We're continuing to work with our existing sites and continuing the expansion as we previously talked about. So we're happy with where our enrollment is going.

[Operator]

The next question comes from Mani Foroohar from Leerink Partners.

[Mani Foroohar, analyst]

A couple of quick ones. First, when we think about the novel expansion population in cholestatic pruritus, can you give us a sense of how you think about the duration of that study and the time horizon which you might see results, recognizing it's a little bit of a heterogeneous population? And then we have a commercial quick follow-up.

[Christopher Peetz, executive]

Maybe Joanne, and I'll let Peter take the follow-up.

[Joanne M. Quan, executive]

Sure. So we are just launching the study now, and as we said, we plan to complete enrollment in 2026. It is a bit of a heterogeneous group of patients, but we expect that some patients will have biliary atresia as a cause, some secondary sclerosing cholangitis and then a variety of other causes. And this is really based on our experience in compassionate use. So we're actually pretty confident in terms of our understanding of the role of IBAT inhibitors in treatment of cholestatic pruritus and think that this extends its potential use to a wide variety of patients who -- each of these would be difficult to study. So we're excited to study them all in this EXPAND study and get some results and hope we support some wider use.

[Mani Foroohar, analyst]

That's helpful. And then when you think about sort of more on the commercial side, obviously, there's a little bit of a -- there's some element of seasonality in this market. And so the pendulum swings one way early in the year and tends to swing the other certainly around 3Q as we saw a couple of years ago. How should we think about the tempo of new patient adds? And any sort of operational details we should think about in terms of seasonality across the next few quarters looking forward?

[Peter Radovich, executive]

I mean one thing to just kind of remind on reflecting back to Q1, we did see in the U.S. with LIVMARLI and the bile acid products impact on our Q1 number from the Change Healthcare cyberattacks. That's one thing to keep in mind as you think about the quarter-to-quarter trends here. And as far as seasonality goes across 3 products, I can't say that we've identified any real seasonality in these products. I mean they're kind of ultra-rare to rare products with relatively low underlying volume, which can lead to kind of quarter-to-quarter variability, quite frankly. But whether that occurs in one quarter versus another, I can't say that there's a really strong effect there.

[Mani Foroohar, analyst]

Okay. And should we -- and on what time horizon should we expect sort of the -- sort of OUS pricing referenced dynamics to play out? Is that something we should think about sort of recurring and sort of eroding itself, playing out over the course of next couple of quarters? Is that primarily 2Q, 3Q event? Like how should we think about baking that into sort of how we model?

[Peter Radovich, executive]

Yes, exactly. We saw the effect in Q2. We expect it in Q3. And our expectation is by the time you're into Q4, that, that effect is gone and all of the kind of demand volume growth that we're seeing flows through to the top line.

[Operator]

Our next question comes from Gavin Clark-Gartner from Evercore ISI.

[Unknown Analyst]

This is [ Yesha ] for Gavin. And we just have 2. The first one, could you just touch on the little confidence in that 45 patients sample size for EXPAND and maybe how you powered the study? And then one follow-up after that.

[Christopher Peetz, executive]

I think I'll let Joanne kind of comment a bit. But I think the one thing to kind of say to give some context here is that now, at this point, IBAT in these cholestatic settings, I think we've seen a pattern here that you can drive really dramatic response if you're at the right dose on bile acids and pruritus. So the thinking behind the study design is based on having actually seen that same profile play out in a number of compassionate use patients. So we've really strong evidence from the individual case studies that, in aggregate, basically make this population. So we feel good about launching the study. That's why we designed it and that's what compelled us to put it together. Maybe Joanne can speak a little bit about sample size.

[Joanne M. Quan, executive]

So the sample size was based on powering based on our primary endpoint, which is an observer-rated feature. So this is a scale that we understand well based on our previous experience in prior studies with LIVRAMLI. So we feel pretty confident that this is an appropriate sample size for us to see a solid treatment effect.

[Unknown Analyst]

Awesome. And then one follow-up. Was there any data from EMBARK that makes you confident enrolling BA patients in this trial?

[Christopher Peetz, executive]

I'll pass that back to Joanne.

[Joanne M. Quan, executive]

Yes. I think it's important to note that the patient population that we're enrolling in EXPAND is actually quite different than the ones that were -- that we did enroll in EMBARK. With EXPAND, we're really taking patients really at any point of their journey. And for biliary atresia, many of these patients will have had a Kasai a number of years ago, but over the course of time, their condition deteriorates and they may develop severe pruritus. So this is quite a different population than EMBARK, where we took really incident patients around the time that they had a Kasai. So this is quite a different patient population. And on top of that, we're including other causes of cholestatic pruritus with a chronic liver disease.

[Christopher Peetz, executive]

[ Yesha ], I'd also add on that. In those compassionate use case studies, there have been biliary atresia patients in there, quite a bit older than the EMBARK age, where they're enrolled as infants. And you do see a kind of hallmark response to IBAT treatment. So I think we've now figured out how to dose these medicines and what settings to advance them in.

[Operator]

The next question comes from Jessica Fye from JPMorgan.

[Jessica Fye, analyst]

I had a few. First, where should we look for presentation of the interim PBC data for volixibat? And what kind of additional detail should we expect when you present those results? For example, are there subgroups where we should expect to learn more? Could we see itch results broken down by severity of disease as defined by ALP levels or additional data on liver biomarkers or more details on the improvements observed in the fatigue dimension of the PBC-40?

And then separately, on the business development front, can you provide a bit of color about just what type of assets and which disease areas are most interesting to you?

And lastly, can you just comment on your IP estate across LIVMARLI and volixibat in terms of what IP you currently have and any pending applications?

[Christopher Peetz, executive]

I can kind of -- maybe I'll take a shot at the first and the last, and then pass it over to Peter to talk about our BD strategy.

I'll first comment on the further data from the PBC study. We're preparing an abstract. We'll work on getting it submitted for an upcoming congress. And we can't really predict when and where that lands and what's in it. So I'll just say that we're looking at a number of the elements that you talked about there to consider for that abstract.

And then on intellectual property, actually I'll direct you to our corporate deck in the backup slides -- we have a summary of that that's been recently added -- and highlight the 2040 family of granted and pending patents that really tie back to the quite unique dosing profile for IBAT in general and LIVMARLI and volixibat in particular that's led to all of these great advances we've seen across the programs that we're talking about here. And there's more detail on this in the backup of our public materials there that you can reference. Maybe Peter can talk about BD strategy.

[Peter Radovich, executive]

Sure. We're focused in rare disease. We really like rare pediatric opportunities. Essentially asking ourselves the question -- programs where we could add a lot of value, underappreciated programs. We have a really strong development, regulatory, commercial group in rare disease. So looking in that kind of a corridor. And we have a high bar. We're very disciplined. We have a really strong base business with a great runway of catalysts in front of it. So we take a lot of scrutiny to these opportunities.

[Operator]

The next question comes from Mike Ulz from Morgan Stanley.

[Unknown Analyst]

This is Robin on for Mike. Just in PFIC, do you expect to pursue a label expansion to patients below 12 months? And then can you just talk about how many patients are typically diagnosed that are below 12 months and what the opportunity there is?

[Christopher Peetz, executive]

Overall, we feel that our label now with this PFIC expansion down to 12 months, it's in a really strong place. We are -- similar to what we do with Alagille. We're evaluating the potential to submit yet another sNDA based on the infant data that's now mature. But frankly, I haven't come to a decision on that yet. So it's something that we could pursue. We feel like we're in a position now where we capture most of the LIVMARLI-targeted patients for both Alagille syndrome and PFIC.

[Operator]

The next question comes from David Lebowitz from Citi.

[David Lebowitz, analyst]

With respect to the EXPAND trial given the heterogeneous population, how do you think the FDA would view it from a label expansion perspective?

[Christopher Peetz, executive]

I'll ask Joanne maybe to talk a little bit about some of the thinking that went into that and discussion with the FDA.

[Joanne M. Quan, executive]

Yes. Interesting that you asked the question that way because -- in fact, the study came about because the FDA actually had suggested it. We were receiving compassionate use request, and so the FDA at one point said, "Why don't you put these into a study?" So this -- the EXPAND study has been designed keeping that input in mind. And so we do think the commonality is really cholestatic pruritus, cholestasis, elevated serum bile acids, and we know the effect that it has -- that this has on pruritus in [indiscernible]. So we're pretty confident in terms of our ability to execute the study and really in terms of the results that we see once, I think, it's executed.

[Operator]

The next question is from Steven Seedhouse from Raymond James Financial Inc.

[Steven Seedhouse, analyst]

Just on EXPAND, how are you going to be measuring pruritus, because it seems like this trial would include pediatric and adult patients depending on the conditions? So I'm just curious how you're going to standardize measuring the endpoint across disease types?

[Joanne M. Quan, executive]

We have an observer-rated ItchRO, which has been validated and which we do have experience with in prior studies. And that's really designed for pediatric population. So it's right of you to recognize that in a pediatric versus adult population we can have different endpoints. But we feel pretty confident in terms of the design of the study and the selection of the endpoint and the fact that we have experience with this endpoint and know how to use it.

[Christopher Peetz, executive]

Yes. And just to kind of follow-up on that. That pediatric data set, that's the primary cohort, 45 patients, and that's where the kind of primary analysis is. Some of the adult scores will be part of a supplemental cohort. And think of the analysis plan designed in that way. Primary is based on pediatric score.

[Steven Seedhouse, analyst]

And so the adults would be self-reported itch? Or would there be a second observer? How does the endpoint look for both?

[Joanne M. Quan, executive]

Right. So for the adults, it's a self-reported endpoint. And that's one reason for us having them in a separate cohort. Based on our discussions with clinicians and just our experience with compassionate use, we do believe the majority of the patients will be pediatric. But we do think there will be some adult patients, and so we're studying them in a supplemental from to analyze those 2.

[Steven Seedhouse, analyst]

Okay. And then the formulation here, is this just going to be the same liquid formulation that's commercially available?

[Christopher Peetz, executive]

That's right. Yes.

[Steven Seedhouse, analyst]

Okay. And then just last question -- and thanks for the multipart question. Are biliary atresia patients that enrolled in EXPAND that were maybe pruritic either on enrollment, and that's for -- excuse me, that enrolled in EMBARK eligible to enroll in EXPAND? Or is anyone who's been treated compassionately eligible to enroll in this study? Or are you excluding anyone with prior exposure to LIVMARLI?

[Christopher Peetz, executive]

Well, first, just on the -- to reiterate on the differences in the setting. The EMBARK population was so young, they were too young even really to recognize pruritus for the most part. You don't see that show up until basically what would have been the very -- even after the time period that EMBARK was looking at. So it's a very distinct setting to go after these -- what are they going to be? Think of them as getting towards grade school age children for a lot of instances.

[Steven Seedhouse, analyst]

So just a follow-up on that, Chris. If there are patients that responded by bile acids or bilirubin or some metric in EMBARK, are they eligible to enroll in EXPAND if they're biliary atresia patient?

[Christopher Peetz, executive]

Yes. The EMBARK study results, recall there that we really -- in that setting, you're not seeing a response signal, right? So those patients either had successful Kasai procedures, you wouldn't expect them to progress again for several years, or they had a transplant already. So it's kind of -- it's -- we didn't even see it as a really relevant question. We can circle back on -- I don't know the exclusion criteria off the top of my head right now, but it was -- it's just such a different patient population. You wouldn't see those necessarily connect.

[Operator]

The next question comes from Brian Skorney from Baird.

[Unknown Analyst]

This is Charlie on for Brian. Just a couple of questions on the bile acid portfolio. Previously, it was sitting around low- to mid-20 per quarter. So just wondering -- you said it's demand growth, but what you're seeing, if you could give a little more detail there? As well as if you're planning for any other opportunities to expand the value you're getting out of CHOLBAM?

[Christopher Peetz, executive]

I'll ask Peter to give some color.

[Peter Radovich, executive]

Yes. And I think I'd kind of go back to what the bile acid products that -- if you're looking at Q1 versus Q2, just a reminder that Q1 was artificially low because of the cyberattack that occurred that impacted pharmacy claim processing in the U.S. So that is just one dynamic to keep in mind. We do expect kind of steady demand growth kind of in line with historical averages and what you've seen over time with -- reminding you that there is quarter-to-quarter variability with these products.

And in terms of CHOLBAM expansion, yes, we think the CHOLBAM label is in a great spot. It facilitates the use and reimbursement of that product across the various settings where it's been established. So no major plans right now to focus on expansion there.

[Operator]

The next question comes from Jon Wolleben from Citizens JMP.

[Jonathan Wolleben, analyst]

A couple on PFIC for me. Wondering -- without talking about sales here, any metrics on the PFIC launch in the U.S. Things are going well. Things that you guys could improve upon throughout the rest of the year? And then with the label expansion recently, can you discuss the added risk of the propylene glycol toxicity? Any observation of that in the clinical trials? Or is this just a risk that FDA wanted to include?

[Christopher Peetz, executive]

I'll kind of break that up between Peter and Joanne to talk about the commercial and safety aspects.

[Peter Radovich, executive]

Certainly, real happy with how we've come out of the gate with PFIC. Have seen -- we had a number of patients transition from our clinical trials, expanded access programs to commercial drug. That proceeded very well. As well as de novo prescriptions for PFIC patients to come in. We've talked about it before that we expect revenue contribution from PFIC in 2024 to be pretty modest given reimbursement. We expect a fair bit of free drug shipment this year for PFIC. It is contemplated a little bit in our guidance, but really expect 2025 to be where PFIC starts contributing more. So a good start.

And then with regards to the propylene glycol and the clinical development program, I'll let Joanne speak to that.

[Joanne M. Quan, executive]

Just to be clear, we have not seen PG toxicity in our clinical studies. And in the context of the PFIC label expansion, we and the FDA looked pretty carefully and kind of considered all of that patient experience data. This concern from the FDA really arose in light of the younger patients being considered for the expansion. And we have seen -- warned about PG toxicity with other labels, for instance. So this is not new to us. We do feel comfortable that the physicians who are prescribing this know their patients, they know what to look for, they're appropriately monitoring. So we think from a practical perspective that this is well handled in terms of the routine patient care.

[Operator]

And the next question is from Ed Arce from H.C. Wainwright.

[Wing Yip, analyst]

This is Thomas Yip [ substituting ]. I got a couple of questions for Ed. Perhaps first, just wondering for CHENODAL how do you characterize the additional commercial opportunity in CTX as an on-label indication, I suppose in terms of quantity and also relative to CHENODAL existing sales.

[Christopher Peetz, executive]

I'll ask Peter to comment on that, give some color on the undiagnosed population for CTX.

[Peter Radovich, executive]

As we look at the CTX opportunity, the best estimates from literature, market research, KOLs, probably somewhere between 1,000 and 2,000 prevalent patients with CTX in the United States. But only 10% of those are diagnosed right now. So it's the best estimate of what we see. So probably the biggest opportunity is if we can increase that 10% to something higher.

So we are investing in disease state awareness initiatives, reaching out to physicians who may see these patients as they're presenting with various symptoms on their journey to a diagnosis and trying to both increase the rate of diagnosis as well as speed up the time to get to the diagnosis. And have seen a lot of interest from prescribers, neurologists and other physicians kind of take interest in that. And then if chenodiol is approved by FDA and we're able to promote -- certainly, the product has never been promoted before. So I think there'll be an opportunity to get out there and, even for the diagnosis patients in clinic, raise awareness of the benefits of -- potential benefits of chenodiol, support reimbursement, things like that.

[Wing Yip, analyst]

Understood. And maybe one more from us. Just one for volixibat. Regarding VANTAGE and VISTAS, has the FDA or the EMA reviewed the interim data that you have so far? Any feedback from any regulatory agencies?

[Peter Radovich, executive]

In the cadence here of regulatory review, we have had a pre-IND discussion designing the studies. And the next opportunity would be after we have final results, is what our plans are. So no kind of interim discussions on plans.

[Operator]

And that was our last question. So I will hand back over to Chris Peetz, the CEO, for any final remarks.

[Christopher Peetz, executive]

Thank you, operator, and thank you all for joining us today. We appreciate the support for Mirum and our programs. Have a good evening. Bye.

[Operator]

And this concludes today's call. Thank you for joining. You may now disconnect from the call.