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DATE
May 4, 2026, 4:30 p.m. ET
CALL PARTICIPANTS
- Chief Executive Officer — Eric Dube
- Chief Medical Officer — Jula Inrig
- Chief Commercial Officer — Peter Heerma
- Chief Financial Officer — Christopher Cline
- Chief Development Officer — William E. Rote
- Senior Vice President, Investor Relations and Corporate Communications — Nivi Nehra
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TAKEAWAYS
- Filspari FDA Approval (FSGS) -- Achieved the first full FDA approval for Filspari in focal segmental glomerulosclerosis (FSGS), establishing it as the first and only approved therapy for patients without nephrotic syndrome.
- Patient Opportunity (Filspari) -- Management now estimates over 100,000 U.S. patients eligible for Filspari across IgA nephropathy and FSGS.
- Peak Sales Guidance -- Company stated a $3 billion peak sales potential for Filspari based on current eligible U.S. patient populations and launch trajectory.
- Filspari Sales Performance -- U.S. net product sales for Filspari grew approximately 88% year over year to $105.2 million in the quarter.
- Record New Patient Start Forms (PSFs) -- Received 993 new patient start forms for Filspari, marking the highest quarterly demand since launch and indicating deepening physician engagement.
- Total Revenue -- Reported $127.2 million in total revenue, including $124.5 million from net product sales, $19.3 million from Thiola and Thiola EC, and $2.7 million from licensing and collaboration (subtotals do not sum to product total due to Filspari’s contribution offset by explained segment reporting).
- Operating Expenses -- Research and development expenses rose to $57.1 million (GAAP), driven by HARMONY study enrollment restart; selling, general, and administrative expenses increased to $80.3 million, primarily for FSGS launch preparations.
- Adjusted Non-GAAP Results -- Adjusted R&D expenses were $51.5 million, and adjusted SG&A expenses were $69.3 million, both up over the prior year.
- Royalty Expense Change -- Royalty expenses moved to a separate line, reported at $24.8 million for the quarter, compared to $12.4 million in the prior-year period, mainly due to the Thiola asset reaching end of accounting useful life, and an increase in Filspari royalties.
- Profitability Metrics -- Reported a net loss of $37.1 million ($0.40 per basic share) on a GAAP basis, narrowing from $41.2 million loss ($0.47 per share) in the prior year; on a non-GAAP basis, achieved net income of $4.1 million ($0.05 per basic share) versus a $16.9 million ($0.19 per share) loss previously.
- Liquidity Position -- Ended the quarter with $352 million in cash, cash equivalents, marketable securities, and receivables, with cash balance at $264.7 million as of March 31, excluding a $25 million milestone to be received in April.
- Pegtobatinase Pipeline Progress -- Restarted enrollment and dosed the first patient in Phase III HARMONY study in classical homocystinuria, targeting topline data in 2027.
- Pegtobatinase Clinical Data -- Phase I/II COMPOSE study of pegtobatinase at 2.5 mg/kg dose twice weekly showed a 67.1% mean relative reduction in total homocysteine at 12 weeks, with sustained effects and tolerability.
- Market Access (Filspari FSGS) -- Over 97% payer pathway access established for Filspari in FSGS, with first patient start forms and reimbursement approvals recorded within one week of FDA approval.
- Therapeutic Positioning -- Filspari designated foundational and nephroprotective in IgA nephropathy, with its use in FSGS expanding due to label consistency with clinical practice and guidelines.
SUMMARY
Travere Therapeutics (TVTX +1.79%) reported the first FDA approval for Filspari in FSGS, immediately broadening its market and recognized as the only approved medicine for this severe kidney disease in patients without nephrotic syndrome. Company leadership characterized demand as the highest to date, with 993 new patient start forms in the quarter, and Filspari sales growing 88% to $105.2 million. The organization restated a $3 billion potential peak sales target for Filspari and now estimates over 100,000 U.S. patients could eventually qualify for treatment across both primary indications. Strategic focus was evident in a rapid commercial rollout, significant physician buy-in, swift payer coverage, and the restart of the HARMONY Phase III study for pegtobatinase, targeting sizeable unmet needs and a late-stage pipeline catalyst projected for topline readout in 2027. The balance sheet closed the quarter with $352 million in cash, equivalents, and receivables, and reported non-GAAP profitability following accelerated revenue momentum and disciplined cost investment.
- The company split royalty expense into a new financial line item for greater transparency, doubling the reported amount year over year due to asset life-cycle changes for Thiola, and increasing Filspari amortization.
- Payer dynamics for Filspari in FSGS were described as "higher first-pass approval" than for IgA nephropathy, and prescriber overlap is driving faster-than-prior launch uptake.
- Travere attributed robust patient retention in IgA nephropathy to observed treatment benefits, and a side effect profile similar to irbesartan, with persistency rates aligning with Phase III PROTECT trial outcomes.
- HARMONY’s pivotal endpoint—reduction in plasma total homocysteine at 12 weeks—received prior FDA alignment, supporting pegtobatinase’s development strategy.
INDUSTRY GLOSSARY
- PSF (Patient Start Form): A formal document submitted by healthcare providers to initiate therapy access and reimbursement for a specific drug candidate.
- FSGS (Focal Segmental Glomerulosclerosis): A rare kidney disorder leading to scarring in parts of the glomeruli, often progressing to kidney failure without appropriate intervention.
- IgAN (IgA Nephropathy): A chronic kidney disease characterized by deposition of the protein immunoglobulin A in the kidneys, leading to inflammation and proteinuria.
- HCU (Classical Homocystinuria): A metabolic disorder arising from enzyme deficiencies, leading to elevated homocysteine levels and multi-system complications.
- Proteinuria: The presence of excess protein in urine, commonly used as a biomarker for kidney damage severity and treatment response.
- Gross-to-net dynamics: The various deductions (rebates, discounts, returns) applied to gross sales to compute net sales recognized by the company.
Full Conference Call Transcript
Eric Dube: Thank you, Nivi. Good afternoon, and thank you for joining us. This has been a tremendous start to the year for Travere Therapeutics, Inc. We have made significant progress across our three strategic priorities. We achieved the first FDA approval in FSGS, we reported a new high in demand for Filspari in IgA nephropathy, and we dosed the first new patient in the Phase III HARMONY study of pegtobatinase following the restart of enrollment. April 13 marked a pivotal point for the FSGS community and Travere Therapeutics, Inc. Achieving the first full FDA approval for Filspari in FSGS established it as the first and only approved medicine for this rare and devastating kidney condition.
With the potential to help more than 30 thousand people living with FSGS without nephrotic syndrome, this approval is a significant indication expansion for Filspari and meaningfully increases the opportunity ahead for us. The first quarter also marked another period of exceptional commercial performance in IgA nephropathy. We delivered another quarter of record new patient start forms. As we look ahead, we are already building upon our experience gained from the successful launch of Filspari in IgA nephropathy and are executing a strong launch in FSGS. Across IgA nephropathy and FSGS, we are now estimating that more than 100 thousand patients in the U.S. could be eligible for Filspari.
Together, we believe this represents a $3 billion potential peak sales opportunity for Filspari, reinforcing a compelling long-term growth trajectory for the company. We are also advancing our pipeline to support further sustainable growth. We recently dosed the first new patient in our pivotal Phase III HARMONY study evaluating pegtobatinase in classical homocystinuria following the restart of enrollment. Importantly, achieving this milestone puts us on track to deliver topline results in 2027. Based on the data we have generated to date, we believe this program has the potential to become the first disease-modifying therapy for the HCU community. We expect there are approximately 7 thousand to 10 thousand people living with HCU globally who would be addressable for pegtobatinase.
I am incredibly proud of our team’s accomplishments and look forward to accelerating Travere Therapeutics, Inc.’s growth as we expand our reach and serve more patients across the rare disease community. With that, I will turn it over to Jula for a medical update. Jula?
Jula Inrig: Thank you, Eric. I am very excited to have the first ever approved medicine for the FSGS community now available for patients. As a reminder, Filspari was approved to reduce proteinuria in adults and children eight years and older with FSGS without nephrotic syndrome. I would like to take a moment to highlight how nephrotic syndrome is defined in clinical practice and what it means in the context of which patients may be eligible for Filspari.
Nephrotic syndrome is a clinical diagnosis and is typically defined by the presence of all three of the following criteria: high levels of proteinuria greater than 3.5 grams per day, low serum albumin levels of less than 3.0 grams per deciliter, and the presence of edema. If a patient is missing any one of these criteria, they are not considered to have active nephrotic syndrome. This is different than nephrotic range proteinuria, which is typically greater than 3.5 grams per day. For example, a patient with 4 grams of proteinuria, low serum albumin, but no edema will be eligible for Filspari. Importantly, nephrotic syndrome is not a chronic state.
If a patient with FSGS presents without nephrotic syndrome, which represents the majority of the FSGS population spanning all types of FSGS, they are immediately eligible for Filspari. For those who initially present with nephrotic syndrome, physicians will typically use immunosuppression induction to try to control the patient’s proteinuria and stabilize them, after which these patients may also become eligible for Filspari. In addition, based on the data from DUPLEX, patients treated with Filspari demonstrated sustained reductions in proteinuria over time, with proteinuria levels reaching approximately 1.5 grams per gram or less on average at study end. At these proteinuria levels, patients would be expected to have a much lower risk of relapsing to nephrotic syndrome.
Based on our discussions with key opinion leaders following the approval, there is wide enthusiasm for using Filspari across the types of FSGS, including among secondary and genetic FSGS. This is supported by our recent publication in CJASN demonstrating consistent efficacy and safety in patients with genetic FSGS, a population often considered the most difficult to treat. Physicians consistently highlight the need for effective, nonimmunosuppressive options for long-term disease management. Now let me talk about IgA nephropathy.
We recently published data in CJASN from the PROTECT study showing that patients with IgA nephropathy who achieved complete remission of proteinuria to less than 0.3 grams per gram experienced a rate of eGFR decline of less than 1 milliliter per minute per year, a rate which is similar to healthy aging. The KDIGO guidelines recommend a treatment approach for IgA nephropathy that addresses both kidney injury and upstream immune drivers, and include Filspari as a first line option for patients at risk of progression. The data published this month reinforced Filspari’s role as a foundational medicine in IgA nephropathy, demonstrating that it helps more patients reach complete remission which is associated with improved preservation of kidney function over time.
Turning briefly to our pipeline, we are pleased to have reinitiated enrollment in our Phase III HARMONY study of pegtobatinase, with the first new patient now dosed. HARMONY is a randomized, double-blind study designed to evaluate the efficacy and safety of pegtobatinase compared to placebo, with a primary endpoint focused on reduction in plasma total homocysteine, a key driver of disease in classical HCU. The primary endpoint for HARMONY is assessed at 12 weeks, consistent with the primary endpoint timing from our Phase I/II COMPOSE study. Patients who complete the HARMONY study are eligible to enroll in the ENCOMPOSE extension study.
This open-label extension will allow us to evaluate long-term outcomes, including sustained homocysteine control, as well as meaningful aspects for patients such as the potential for greater dietary flexibility and self-administration. This program is supported by data from our Phase I/II COMPOSE study where pegtobatinase demonstrated rapid, sustained, and dose-dependent reductions in total homocysteine levels. At the 2.5 mg/kg dose twice a week, pegtobatinase delivered a 67.1% mean relative reduction in total homocysteine from baseline to 12 weeks, as well as maintenance of mean total homocysteine below the clinically meaningful threshold of 100 micromoles, and was generally well tolerated.
Pegtobatinase has the potential to become the first disease-modifying therapy for patients living with classical HCU, and as Eric mentioned earlier, we expect topline data from the HARMONY study in 2027. Finally, we continue to generate and share new data across IgA nephropathy, FSGS, and HCU, and we look forward to upcoming medical meetings. At NKF this week and ERA next month, we will present additional analyses in both IgAN and FSGS. Now I will turn it over to Peter for a commercial update. Peter?
Peter Heerma: Thank you, Jula. I am pleased to share that we started the year strongly and set new records with our Filspari performance. The first quarter marked the highest demand to date as we received 993 new patient start forms, reflecting continued expansion among new prescribers and deepening utilization across established accounts. Importantly, we continue to see an increasing number of practices treating multiple IgA nephropathy patients with Filspari, with VVU as a meaningful indicator of physicians’ confidence with the medicine’s foundational and nephroprotective positioning. As new treatment options become available for this indication, Filspari remains the most commonly prescribed medicine approved for IgA nephropathy in the U.S.
This broad utilization supports our confidence in Filspari’s continued growth potential in IgAN, and we are seeing strong demand at the start of the second quarter. For the first quarter of 2026, we reported approximately $105 million in sales prior year revenue. Despite the typical beginning-of-the-year insurance resets and gross-to-net dynamics, as well as recognizing fewer revenue shipping weeks, the strength of our performance in IgAN and the momentum we have with Filspari is directly relevant as we enter the FSGS launch. There is significant overlap in the prescriber base between these two indications, and many nephrologists already have experience with Filspari in their IgAN patients.
This will support early adoption in FSGS patients, and we anticipate a faster uptake compared to the initial IgAN launch. In fact, early feedback from the FSGS community has been overwhelmingly positive. We received our first patient start forms on the first day following approval. We are encouraged by the enthusiasm and engagement we are experiencing. Having spent time in the field over the past two weeks, I have seen that enthusiasm firsthand in discussions with nephrologists in their offices. It reinforces our belief that the FSGS opportunity is expected to be even bigger than IgA nephropathy. Established payer access in IgAN is helping to position Filspari in a supportive access environment in FSGS.
In fact, we saw our first FSGS reimbursement approvals in the first week. Payers often manage access at the product and indication level, and our team is focused on expanding payer plans and formularies to include Filspari for FSGS. While education on the FSGS indication will be important, we are starting from a position of strength with an experienced commercial team and established infrastructure. We believe there are more than 30 thousand patients in the U.S. with FSGS who are currently eligible for Filspari, and we expect that number to grow. In summary, the start of 2026 reflects exceptional commercial execution with record demand and revenue growth.
With our continuing performance in IgA nephropathy and Filspari’s recent FSGS approval, I am confident in our ability to continue delivering strong, sustained growth and long-term leadership across these rare kidney disease indications. I am incredibly proud of our team and the impact they continue to have on patients and physicians. I am excited for what lies ahead for us in 2026. I will now turn the call over to Chris for the financial update. Chris?
Christopher Cline: Thank you, Peter. As you have heard from the team, we delivered another strong quarter of execution across the business, and recently, we achieved an important milestone with Filspari’s approval in FSGS that further strengthens our outlook for continued growth. In the first quarter, we generated $124.5 million in total U.S. net product sales, reflecting strong year-over-year growth. Importantly, U.S. net product sales of Filspari grew approximately 88% year-over-year to $105.2 million despite typical beginning-of-year gross-to-net impact and fewer revenue recognition days. As Peter noted, for Filspari, we recognize revenue when product is delivered to our specialty pharmacies, which typically occurs a couple of days after shipment from our logistics partner.
Due to the quarter-end timing and typical early-week ordering patterns, the first quarter had one fewer shipping week than usual. As a result, some Filspari shipments made in the first quarter will be recognized in the second quarter. Adjusting for this dynamic and supported by record demand during the first quarter, we believe Filspari is on a strong trajectory in IgA nephropathy for the balance of the year. Elsewhere, Thiola and Thiola EC contributed $19.3 million in U.S. net product sales during the first quarter, and we recognized $2.7 million in licensing and collaboration revenue, resulting in $127.2 million in total revenue for the first quarter.
Moving to operating expenses, our research and development expenses for the first quarter of 2026 were $57.1 million, compared to $46.9 million for the same period in 2025. On a non-GAAP adjusted basis, R&D expenses were $51.5 million compared to $42.2 million for the same period in 2025. The increase is primarily driven by the restart of enrollment in the Phase III HARMONY study of pegtobatinase during the quarter. Selling, general, and administrative expenses for the first quarter of 2026 were $80.3 million compared to $60.4 million for the same period in 2025. On a non-GAAP adjusted basis, SG&A expenses were $69.3 million compared to $53.3 million for the same period in 2025.
The increase is primarily attributable to investments in preparation for Filspari’s launch in FSGS, including an expanded field team as well as investments in IgA nephropathy. Beginning in the first quarter, we revised the presentation of our amortization expense associated with royalty and milestone payments to a separate royalty expense line item, in order to provide greater transparency to underlying operating expenses. For the quarter, we recognized $24.8 million in royalty expense compared to $12.4 million for the same period in 2025.
The increase is primarily a result of the Thiola intangible asset reaching the end of its accounting useful life, resulting in amortization of the full amount of the royalty payments accrued this quarter, as well as an increase in capitalized Filspari royalties. Under accounting policy, Thiola royalties will now be expensed to royalty expense in the same quarter as the corresponding net sales. Contractual milestones and royalty payments related to Filspari will continue to be capitalized to intangible assets and amortized on a straight-line basis over its useful life, with only amortized expense recognized within royalty expense.
Total other income, net, for the first quarter of 2026 was less than $1 million, compared to $1.5 million for the same period in 2025. Net loss for the first quarter of 2026 was $37.1 million, or $0.40 per basic share, compared to a net loss of $41.2 million, or $0.47 per basic share, for the same period in 2025. On a non-GAAP adjusted basis, net income for the first quarter was $4.1 million, or $0.05 per basic share, compared to a net loss of $16.9 million, or $0.19 per basic share, for the same period of 2025. As of 03/31/2026, we had cash, cash equivalents, marketable securities, and receivables of approximately $352 million.
Receivables include the $25 million sales-based milestone payment from Mirum Pharmaceuticals, which was recognized in 2025 and received in April. This is not yet reflected in our cash balance of approximately $264.7 million as of March 31. Looking ahead, we are well positioned to fund our operations with existing resources, investing with discipline across our key priorities, including the commercialization of Filspari in IgA nephropathy and FSGS, ongoing evidence generation, advancement of the pivotal HARMONY study of pegtobatinase in HCU, alongside building further pegtobatinase supply. We expect continued strong demand in IgA nephropathy to drive sustained revenue growth, with FSGS further contributing to our top-line trajectory.
Overall, we believe our balance sheet, expected top-line expansion, and disciplined approach to investing in our priorities position us to execute with confidence and deliver durable long-term growth. I will now turn the call over to Eric for his closing remarks. Eric?
Eric Dube: Thank you, Chris. As we look ahead, our priorities are clear: continue to drive growth by reaching more patients with IgA nephropathy, execute a strong launch in FSGS, and enroll our HARMONY study of pegtobatinase. With Filspari now approved in IgA nephropathy and FSGS, and a pipeline progressing into late-stage development, we believe we are well positioned to deliver meaningful value for patients and shareholders over the near and long term. With that, I will turn the call back over to Nivi for Q&A. Nivi?
Nivi Nehra: Thank you, Eric. We will now open the call for questions. Operator, we can now open up the line for Q&A.
Operator: Thank you. We will now begin the question and answer session. If you would like to ask a question, please press 1 on your keypad to raise your hand. To withdraw your question, press 1 again. We ask that you pick up your handset when asking a question to allow for optimum sound quality. If you are muted locally, please remember to unmute your device. As a reminder, we ask that you limit yourself to one question. If you have another question, please rejoin the queue. Please stand by while we compile the Q&A roster. Your first question comes from the line of Joseph Schwartz with Leerink Partners. Joseph, your line is open. Please go ahead.
Analyst: Hey, guys. This is Will Soghikian on for Joe. Thanks for taking our question, and congrats on all the progress this quarter. One for us on FSGS. You have messaged several times that the launch is expected to progress at a faster rate than IgA nephropathy. Could you please characterize what you are seeing at this early stage and how it compares to the original IgAN rollout a few years ago? It seems like the full approval here could also make a difference, especially since we know nephrologists are sometimes slower to adopt innovative medicines. Is what you are seeing in these early days supportive of a more rapid FSGS launch? Thanks so much.
Eric Dube: Will, thank you so much for the question, and I am very pleased with the early performance and particularly the execution from our field teams. Peter, with that, why do you not give some color to what you are seeing in the early part of the launch?
Peter Heerma: Absolutely, Eric, and Will, thank you for that question. Indeed, we are confident in a faster uptake in FSGS relative to the IgAN launch for multiple reasons. First of all, this is a very high unmet need, and this is the fastest progressive glomerular disease as well, whereas for IgAN we really had to establish the urgency to intervene earlier. In addition to that, we built upon very strong brand awareness, and many of the physicians already have experience with Filspari, given this is basically the same core point for IgA nephropathy. From a payer perspective, we already are in most of the formularies and payer plans. We currently have over 97% pathway to access for patients.
We built upon a very strong foundation, and that gives me confidence that we will have a more rapid uptake in FSGS relative to our initial IgAN launch, and we believe it is an even bigger opportunity with FSGS than IgAN. Thank you so much.
Operator: Next question comes from the line of Tyler Van Buren with TD Cowen. Tyler, your line is open. Please go ahead.
Analyst: Hi. This is Greg on for Tyler. Thanks for taking my question. You noted that the first FSGS PSFs arrived the day after approval, and reimbursed treatment started within one week. How many FSGS PSFs have you recorded thus far in the launch? And what proportion of early starts are coming through payer authorizations versus exceptions or appeals? What are you seeing on initial behavior in general? Thanks.
Eric Dube: Greg, thanks so much for the question. While it is too early for us to be able to quantify some of that, Peter certainly can provide some qualitative and directional views on the demand and the payer dynamics. Peter?
Peter Heerma: Yes, great. I would love to answer that question with specifics, but this is a Q1 call, so I am looking forward to sharing more with you on the second quarter call. Following my answer to your earlier question on the faster uptake versus IgA nephropathy, I would say everything we are seeing so far is confirming what I have said with regards to a faster uptake than our initial IgA nephropathy launch. That counts both for demand as well as for the early approval rates that we are seeing with payers. We are actually seeing a higher first-pass approval at the payer level than what we saw initially for IgAN.
Operator: Your next question comes from the line of Anupam Rama with JPMorgan. Anupam, your line is open. Please go ahead.
Anupam Rama: Hey, guys. Thanks so much for taking the question. On the FSGS launch, if you could build upon some of your prior comments. I know you mentioned that there is a need to further educate physicians. I know that it is only three weeks post approval, but I was wondering if you could speak to what is resonating with physicians in terms of the product label and the product profile, and within that, where you think the education is required? Thanks so much.
Eric Dube: Anupam, thanks so much for the questions. Peter, why do you not take that, and Jula, I know your team has got extensive engagements with thought leaders; you can add anything that you might want to. Peter?
Peter Heerma: Happy to take that question, Anupam. To my earlier point, we are seeing overwhelmingly positive responses from physicians, but you still have to educate them. I was in the field a few days, and many of the community nephrologists in particular may not know yet that Filspari was approved. So that awareness you have to build. You have to educate physicians also on the label, in particular around not being in nephrotic syndrome. That requires some education. Once you explain that, it resonates with physicians because it is very similar to how patients are being treated today. It is actually very consistent with the guidelines. Jula, maybe you can provide some context on that.
Jula Inrig: Yes, thanks. Our team, as Eric mentioned, has been out at conferences, advisory boards, and seminars. I would say that the approval is getting resoundingly positive feedback from physicians. This patient community has been waiting a long time, and they are excited to have a nonimmunosuppressive treatment option to control these patients and get their proteinuria down. You asked about education. Part of it is a reminder that active nephrotic syndrome is not the same as nephrotic range proteinuria, so we are educating around that. But as Peter mentioned, it is very positive and there is excitement to have this option to treat their patients.
Anupam Rama: Thanks so much for taking my question.
Eric Dube: Thanks, Anupam.
Operator: Your next question comes from the line of Prakhar Agrawal with Cantor Fitzgerald. Prakhar, your line is open. Please go ahead.
Prakhar Agrawal: Hi. Thank you for taking my questions, and congrats on the quarter. Maybe going back to your comments on faster uptake than IgAN, when I go back to the IgAN launch in the first few full quarters, you had 400 to 450 patient start forms. Is that how we should think about the uptake for FSGS as well? And secondly, on access, do you expect payers to cover the secondary FSGS patients broadly as well despite the segment not being tested in Phase III? Are you hearing any pushback from the payers? Thank you so much.
Eric Dube: Prakhar, thanks for the questions. With regard to uptake, we are not going to be providing guidance, and we will not be breaking out the PSFs by indication as we move forward. I will reinforce what Peter shared—that everything we are seeing so far in the first three weeks of launch has confirmed what we have been saying around a faster uptake, around an eagerness to prescribe, and the payer dynamics really helping to get patients from PSF onto therapy. With that said, Peter, why do you not take the question around payer access and the different types of FSGS—secondary, etc.—and any pushback?
Peter Heerma: Absolutely. Maybe good to start with repeating what I just mentioned—that I am most encouraged by the early approval rates that we are seeing for FSGS that are higher than what we saw initially for IgA nephropathy. For context, payers understand that FSGS is a more rare disease compared to IgA nephropathy with a more progressive nature. This is what we have been educating payers on over the last six to seven months. In that context, payers are not really focused on types or subtypes of FSGS. They understand the common injury pathway and how Filspari is the first approved medicine for this patient population that is rapidly progressing.
That is what we are hearing and seeing so far in the context of our conversations with payers over the last six to seven months.
Prakhar Agrawal: Thank you.
Eric Dube: Thank you.
Operator: Your next question comes from the line of Vamil Divan with Guggenheim Securities. Vamil, your line is open. Please go ahead.
Vamil Divan: Great, thanks for taking my question. I wanted to get back to the topic around the history and nephrotic syndrome. We have spoken to some physicians since the approval, and there seems to be some confusion about this and whether they can prescribe Filspari in these patients or not. So just curious if you can elaborate there in terms of do you think physicians will focus on history of nephrotic syndrome. It sounds like maybe you mentioned that there is some education you still need to work on.
Maybe just elaborate on that in terms of what you are doing to make sure it is clear, because it certainly sounds like your perspective is that this should not be a limiting factor.
Eric Dube: Thank you, Vamil, for the question. We firmly believe this is not going to be a challenge; it is certainly an opportunity to educate. Jula, why do you not talk about the efforts that you are doing and the reaction from nephrologists? Peter, you can talk about how payers may be thinking about this topic.
Jula Inrig: This has not been an area of focus from physicians, and we have had a fair bit of engagement, and so has Peter’s team. We do not believe that history of nephrotic syndrome should deter a physician from prescribing Filspari. The reason for that is because of our labeled indication. It is for patients without active nephrotic syndrome. This is very much aligned with KDIGO, which recommends patients with active nephrotic syndrome be treated with immunosuppression, while those without it receive optimized supportive foundational care, and that is where Filspari provides the best treatment option for these patients.
Peter Heerma: To build upon that from a payer perspective, as I mentioned earlier regarding a more rare disease with a more rapidly progressive manifestation, the most important part is to educate payers that nephrotic syndrome is a dynamic state. It is not a chronic state, and payers understand that. These conversations have not really come up as an obstacle, given FSGS is a rapidly progressing disease and payers understand that as well.
Vamil Divan: Okay. Thank you.
Eric Dube: Thanks, Vamil.
Operator: Your next question comes from the line of Gavin Clark-Gartner with Evercore. Gavin, your line is open. Please go ahead.
Gavin Clark-Gartner: Hey, guys. Thanks for taking the question. I actually wanted to pivot over to IgA nephropathy quickly. What are you seeing as discontinuation rates over time here—let us say at the one-year mark and the two-year mark since patients start therapy? How does that compare to what you saw in the IgAN Phase III?
Eric Dube: Peter, why do you not take that question?
Peter Heerma: The compliance and persistence rates for Filspari in IgA nephropathy have been very high. We have not given specifics on the numbers, but we have not seen any change or disruption in those rates as well. We have high confidence both from the patient perspective that they are being helped, and from the physician perspective that they see this product works for a patient population that historically did not have a treatment option. Jula, maybe you can provide context on what we are seeing versus what we saw in the PROTECT trial.
Jula Inrig: I would say consistent. We saw high persistence of patients staying on treatment during the two-year double-blind trial, and I think it is very aligned with what we are seeing commercially. Part of the reason for that is patients have that positive reinforcement—their proteinuria goes down, they see it, and they feel like they are getting better. With a side effect profile very consistent with irbesartan, patients tend to stay on therapy, and they understand this should be truly lifelong. As long as they keep their kidneys, they should stay on Filspari.
Gavin Clark-Gartner: Great. Thanks.
Operator: Your next question comes from the line of Mohit Bansal with Wells Fargo. Mohit, your line is open. Go ahead.
Sadia Rahman: This is Sadia Rahman on for Mohit. Thanks for taking our question. The patient start form number this quarter again looks very impressive. Can you provide some color on the conversion rate for these forms to patients ultimately starting treatment, and any reasons for any drop-off along the way? Thank you.
Eric Dube: Thanks, Sadia. Peter, why do you not take that?
Peter Heerma: I am glad you reflected on the 993 patient start forms as impressive, because I am really impressed with my team that is continuing to show growth in IgA nephropathy in a rapidly changing environment. With regards to conversion, I would say we continue to convert those patients quite rapidly over time. We continue to make improvements, though where we are right now is not as dramatic as what you saw in the very beginning. We do not see any drop-offs or changes.
With regards to translation of patient start forms into revenue—that may be part of your question—I think Chris provided more on that with regard to fewer ordering and shipment weeks in Q1, as well as the typical gross-to-net dynamics that you usually see in Q1. I hope that answered your question, Sadia.
Sadia Rahman: Yes. Thank you.
Eric Dube: Thank you.
Operator: Your next question comes from the line of Laura Chico with Wedbush Securities. Laura, your line is open. Please go ahead.
Laura Chico: Thank you very much for taking the questions. I apologize if this has been asked already, but one question I had was on IgA nephropathy dynamics for Filspari. It is great to see the PSF number considering the increase, and I am presuming that is predominantly from IgA nephropathy patients. But we also had a competitive update—Novartis indicated the ALIGN confirmatory study for ianalumab did not reach its statistical significance. While they will pursue a full FDA approval, I am just wondering how that changes your views on the competitive landscape dynamics for IgA nephropathy with Filspari. How are you thinking about pushes and pulls on demand drivers in 2026?
And then I have a quick follow-up, if that is okay.
Eric Dube: Thanks, Laura. Peter, why do you not take that, and certainly, Jula, add any further perspective as you see the evolution or consistency of the treatment landscape.
Peter Heerma: Happy to answer that question. I think most important is that this is a market in development. Most growth in this marketplace is not coming from competitive share, but mainly from growing the market. That is exactly what we see and what we were anticipating. I think Filspari is very well positioned to grow in this marketplace because it is really replacing RAS inhibition. There is no other product that has that ability to do so. Most competition is in the other sector—more immunosuppressive agents where B cells are now playing together with complement inhibitors and historical steroids.
Physicians understand the positioning of Filspari very well as the foundational nephroprotective treatment option, and they understand Filspari’s positioning relative to alternatives such as endothelin receptor antagonists and others.
Eric Dube: And just one thing, Laura, before you get to your next question. You had asked about the PSF increase. That is all based in Q1, so that would be IgA nephropathy before the approval of FSGS. We do expect to see an acceleration of demand over time as we look at both indications. But that very solid number of 993 patient start forms in Q1 reflects our performance in an increasingly competitive landscape of multiple treatment options. I think it is a really impressive number that Peter’s team has been able to deliver. Why do you not get to your follow-up, Laura?
Laura Chico: Yes, just real quick. We have got a few weeks in April since the FSGS approval. It does seem like a couple of PSFs are coming through here. Just out of curiosity, are these originating from existing Filspari IgAN prescribers versus newly activated FSGS prescribers? And should we be presuming these are already established prescribers in these early days, in these early quarters of launch? Thanks very much.
Eric Dube: Laura, thanks so much for the question. It is early. Peter, why do you not comment on what you are seeing thus far?
Peter Heerma: It is indeed early. We see both, to be honest, and more color to come in the Q2 call. In this context, it is good to talk about the halo effect. I have spoken about the halo effect in the past—the experienced prescribers for IgA that now also adopt Filspari for FSGS. But vice versa, we are starting to hear anecdotes from physicians that have been on the fence; they are excited about starting in FSGS and, based on that, now are also excited to start prescribing in IgA. I think a halo effect will benefit both indications.
Operator: Your next question comes from the line of Maury Raycroft with Jefferies. Maury, your line is open. Please go ahead.
Maury Raycroft: Hi. Thanks for taking my question, and congrats on the quarter. Maybe following up on Laura’s question, focusing on PSFs. I am trying to think about how to estimate that going forward for IgAN. You talked about atrasentan as a competitor, but Otsuka also had a good quarter for PSF growth in IgAN. Do you have any perspective on how Otsuka is launching their drug and how you are factoring that into your estimates? Any more perspective you can offer on switching to biologics and how you are thinking about that in your total estimate for $3 billion in peak sales?
Eric Dube: Let me take a couple of those, and Peter can comment on what he is seeing from a competitive standpoint and switching. First, PSFs moving forward will be provided in aggregate. I recognize, Maury, you are trying to figure out what is in IgAN alone. I would say there is no reason to believe we cannot continue this level of performance because of the number of patients out there and the very unique positioning that nonimmunosuppressive, kidney-targeted therapies have, which Peter can speak to. With regard to the peak year sales of $3 billion, that really is based on continued growth in both indications. We have talked about FSGS being a larger opportunity than IgA nephropathy.
We fully expect growth in both, but the much faster uptake in FSGS is going to allow us to really reach more of those patients over time and contribute more meaningfully to growth at peak. We really do not see the dynamics as taking away from our opportunity or performance. Peter, why do you not talk about that in the context of new patients as well as switches?
Peter Heerma: The most important point is that we do not see B cell–targeting therapies as a direct competitor for Filspari. Conceptually, the way patients are being treated for IgA nephropathy is how it was done in the past with RAS inhibition, and on top of that you used steroids when needed. That concept is not changing—only now, for RAS inhibition, you have Filspari as a superior option for those patients. For patients that need additional treatments, you now have B cell therapies potentially replacing steroids. The growth in this market is not so much competitive growth; it is really developing the market. This is a highly underdeveloped market historically.
There are still so many patients treated with generic RAS inhibitors and generic steroids. You have better options available right now, and the KDIGO guideline is reinforcing that. You have a more ambitious treatment target nowadays, so that will often mean more combination therapy as well. There is space for multiple products to grow, and Filspari is very well positioned in that nephroprotective foundational treatment category.
Eric Dube: Thank you, Peter. And, Maury, maybe if we take a step back, one of the things I would like to reinforce is we talked over the last couple of years about new entrants coming and really helping to accelerate growth within the IgA nephropathy market. That is not going to take away from our performance and our outlook; that is exactly what we are seeing with the entrants that have come to the IgA nephropathy foundation.
The performance that we posted this quarter really reflects the opportunity that we have, but perhaps more importantly, the opportunity that patients who have been undertreated with off-label therapies now have to benefit from innovation moving forward, both with Filspari as well as other therapies. That is going to be the foundation for continued performance of Filspari.
Maury Raycroft: Got it. That is really helpful. Thank you very much.
Eric Dube: Thanks, Maury.
Operator: Your next question comes from the line of Jason Zemansky with Bank of America. Jason, your line is open. Please go ahead.
Jason Zemansky: Good afternoon. Congrats on the progress, and thanks so much for taking our question. Maybe, Jula, one for you. I was curious where you are seeing Filspari sequenced in FSGS. Is it in lieu of the ACE/ARBs? Are these patients usually already on SGLT2s? We have gotten some mixed feedback regarding whether this drug is going to be used first line or whether in those uncontrolled while already on an ARB or an ACE and an SGLT2.
Jula Inrig: Thanks for the question. Just like IgA nephropathy, the vast majority of patients are already on some form of a RAS inhibitor, an ACE or an ARB, even by the time they get sent to the nephrologist—so predating their diagnosis. It is slightly lower than IgA nephropathy because kids may or may not always be on an ACE inhibitor, but you are still talking at more than 70% to at least 80% of patients on some form of foundational treatment. As far as SGLT2 inhibitors, I would say they are used—just potentially not quite as prevalent because we do not have as great data around SGLT2s.
But, as Peter has mentioned multiple times, these patients are at very high risk for rapid progression to kidney failure, so physicians will be pulling at as many things as they can in their tool belt to try and stabilize these patients. Now they have Filspari, which is better head-to-head versus a RAS inhibitor, so they are going to take patients off their RAS inhibitor and initiate Filspari, ideally at their next clinic visit when they see these patients.
Eric Dube: And, Jula, maybe I can add something else for Jason’s question. Particularly for those patients with primary FSGS and particularly those with active nephrotic syndrome, they are—based on the guidelines—going to be treated with an immunosuppressant. Once they are not in active nephrotic syndrome, they would be eligible and likely placed on Filspari. So in terms of it not being first-line use, it is a slight nuance. But that is also an opportunity moving forward.
Jula Inrig: No, that is accurate.
Eric Dube: Thanks, Jason.
Jason Zemansky: Thanks.
Operator: Your next question comes from the line of Alexander Thompson with Stifel. Alex, your line is open. Please go ahead.
Alexander Thompson: Thanks so much. Just a quick follow-up question on IgAN, and then maybe I would like to ask about pegtobatinase as well. Maybe, Chris, are you able to quantify the shipping week impact at all? That would be helpful for the quarter. And then for pegtobatinase in the Phase III, congrats on restarting that. Have you met with the FDA review division recently, and how confident are you that total homocysteine is still going to be an approvable endpoint here? Thank you.
Eric Dube: Alright, Chris, and then we can turn that over to Bill for the pegtobatinase question.
Christopher Cline: Thanks for the question, Alex. We do not typically break down individual weeks of revenue. What I would point you to—the best proxy—is to take the average for the quarter. We had about 12 weeks of revenue recognition within the quarter, and that will get you to the best proxy there.
William E. Rote: I will take the pegtobatinase question. We have got Breakthrough Therapy designation for pegtobatinase, so that allows us to have a lot of interaction with the FDA. Through that process, we reached alignment on the endpoint for the HARMONY study, and—as noted in the prepared remarks—that mirrors the timing of what we saw in the COMPOSE study. It was in collaborative discussion with the agency where we settled on that 12-week endpoint.
Alexander Thompson: Had that happened since the original alignment this year or since you redosed, or was that originally the alignment?
William E. Rote: That is the original discussion. We have not had reason to discuss the endpoints of the trial once it was agreed and aligned upon.
Alexander Thompson: Okay. Thank you.
Operator: Ladies and gentlemen, this concludes the question and answer session of today’s conference call. I will hand the call back over to Nivi.
Nivi Nehra: Great. Thank you everyone for joining today’s call. Have a great rest of your day.
Operator: Thank you for attending. You may now disconnect.
