Good day, and welcome to the BioCryst First Quarter 2025 Earnings Conference Call. All participants will be in listen-only mode. [Operator Instructions] After today's presentation, there will be an opportunity to ask questions. [Operator Instructions] Please note that this event is being recorded. I would now like to turn the conference over to John Bluth with Investor Relations with BioCryst. Please go ahead.

Thank you. Good morning, and welcome to BioCryst's First Quarter 2025 Corporate Update and Financial Results Conference Call. Today's press release and accompanying slides are available on our website. Participating with me today are CEO, Jon Stonehouse; Chief Commercial Officer, Charlie Gayer; and Chief R&D Officer, Dr. Helen Thackray. Following our remarks, we will answer your questions. Today's conference call will contain forward-looking statements, including those statements regarding future results, unaudited and forward-looking financial information, as well as the company's future performance and/or achievements. These statements are subject to known and unknown risks and uncertainties, which may cause our actual results, performance or achievements to be materially different from any future results or performance expressed or implied in this presentation. You should not place undue reliance on these forward-looking statements. For additional information, including a detailed discussion of our risk factors, please refer to the company's documents filed with the Securities and Exchange Commission, which can be accessed on our website. In addition, today's conference call includes non-GAAP financial measures. For a reconciliation of these non-GAAP measures against the most directly comparable GAAP financial measure, please refer to the earnings press release posted in the press release in section of our Investor Relations website at www.biocryst.com. I'd now like to turn the call over to Jon Stonehouse.

Thank you, John. We've started 2025 with another quarter of outstanding performance. As you will hear from Charlie in more detail, the U.S. commercial team made tremendous progress in moving patients on ORLADEYO from free drug to paid at a much faster rate than we expected. The result is quarterly revenue of $134 million. This improvement in the paid rate impacts revenue performance in Q1, but also through the rest of the year, leading us to raise annual revenue guidance for ORLADEYO to between $580 million and $600 million, which is 33% to 37% growth over last year. Our improved revenue growth significantly increases our margins and has also accelerated our cash flow and profitability goal by a year. We now expect to be profitable on a full year basis this year. This increased financial strength and the positive cash flow it generates enabled us to pay down $75 million of our debt in April, while continuing to invest in and advance our pipeline. In addition, we are now moving into ORLADEYO revenue levels where we no longer pay a royalty on sales above $550 million and we're getting closer to our peak sales for ORLADEYO of $1 million. In the current environment of uncertainty, having a company with growing sustainable revenue, an advancing pipeline and financial strength to be profitable, pay down debt and be independent of the markets is hard to find in our industry, but that's exactly what we have at BioCryst. With that, I'll turn it over to Charlie to discuss our fantastic first quarter results. Charlie?

Thanks, Jon. The launch trajectory for ORLADEYO has been consistently strong for the past four years, but the first quarter of 2025 was our best yet because of the combination of great demand generation and amazing progress helping patients gain access to therapy. As we described previously, U.S. patient demand in 2024 matched the first year of the launch. Our team continued this momentum as first quarter new prescription slightly exceeded our best quarter from last year. In addition, our latest patient survey showed that regardless of their current treatment status, the percentage of U.S. HAE patients who strongly prefer oral prophylaxis grew to 70%, up from 51% in 2023, as you can see on Slide 7 in today's presentation. And HAE treaters are increasingly convinced that ORLADEYO is very effective and convenient for patients based on their individual experience and the rapidly expanding body of real world evidence that they have seen. ORLADEYO is becoming their treatment of choice. What really drove Q1 performance though was a 10 percentage point jump in the rate of paid patients in the U.S. Over where we ended 2024. We expected that level of improvement to take three years. We did it in four months. The Inflation Reduction Act drove about two-thirds of the improvement because the IRA is achieving its intent of helping Medicare patients afford their prescription co-payments. Medicare patients were not only able to afford their ORLADEYO prescriptions, but they were able to do so earlier in the quarter than expected. And we also continue to make great progress among the roughly 60% of ORLADEYO patients who have commercial insurance. The paid rate in that segment increased to 84% as we further improved our ability to convert patients from long term free product to paid product. By the end of…

Thank you, Charlie. Good morning. Today, I'm pleased to share an update on recent significant milestones for our pipeline programs. First, we've submitted our pediatric NDA for ORLADEYO to FDA, introducing an oral granule formulation for patients aged two to 11 with additional filings in Europe, Japan and Canada also this year. This would be a significant advance in the treatment of children with HAE as it would be the first targeted oral prophylactic therapy for this age group. Next, I'm pleased to report that we received authorization to initiate patient enrollment for both the pipeline programs following ORLADEYO, BCX17725 in Netherton syndrome and avoralstat in diabetic macular edema, which is an important step on our path to having initial clinical data in patients for both programs by the end of the year. Today, I'll focus on the Netherton syndrome program in detail and provide more information about the trial design, what we're looking for and what to expect by the end of the year. First, I'll describe why we're so excited about the potential for 17725 as a transformative treatment for people living with Netherton syndrome. This is a devastating illness. Its consequences are very serious and lead to lifelong impacts on health and well-being. We've heard from patients that the lack of treatment leads them to withdraw from medical care. We recently heard exactly the same feedback from our clinical site investigators. Just as it's been for other rare diseases like HAE, we expect introducing a new potential treatment that could revolutionize care, will attract patients back into the care system and into clinical trials. We designed 17725 to address the fundamental pathology that causes Netherton syndrome, every aspect of which is ultimately caused by a genetically determined lack of an essential skin protein called SPINK5, also known…

Thanks, Helen. We are exiting the first quarter in a great financial position with stronger than expected revenue growth, increasing full-year revenue guidance, accelerating full-year profitability to this year, and last month we've reduced our outstanding debt. While you can find our detailed first quarter financials in today's press release, I'd like to draw your attention to a few items. Total revenue for the quarter came in at $145.5 million, $134.2 million of which came from ORLADEYO. Of that ORLADEYO total revenue, $120.2 million or 89.5% is coming from the U.S. Operating expenses excluding stock-based compensation were $102.9 million for the quarter, up from $93.6 million in the same quarter last year. This was primarily driven by an increase in commercial expense to support our growing ORLADEYO revenue, our newly launched regions like Spain and Italy, and expanded international operations, including global commercial support activities across finance, HR, IT, and supply chain. Operating profit for the first quarter of 2025 was $21.2 million and net income was slightly positive. Cash at the end of the quarter was $317 million. As a result of the significant and durable improvements to revenue that Charlie discussed, we are revising our revenue guidance by $45 million to $50 million above our prior guidance, and which represents, as I mentioned before, a 33% to 37% growth over last year. We now expect non-GAAP operating expense for the year to be $440 million to $450 million, a $15 million increase over our prior guidance, driven by expenses supporting our commercial growth and an increase in COGS as sales of RAPIVAB increased. The result of this strong revenue performance combined with our continued focus on disciplined capital allocation is that we now expect to be profitable for the full year on a net income and positive cash flow basis this year. This is one year earlier than we previously planned. Further, based on this improved financial strength in April, we made a paydown of $75 million on our debt with Pharmakon and reduced our outstanding debt to $249 million. As a result, we expect to save approximately $23 million in interest payments over the life of the debt net of the early prepayment penalty. I am immensely proud of the continued focus of our employees who are delivering meaningful improvements in patients' lives both today and in the future. Our commercial and support teams are driving access and usage of ORLADEYO and our R&D team is advancing our pipeline to address challenges in new disease areas where patients are underserved. Financially, we are driving revenue growth and well on our way to $1 billion at peak, efficiently allocating capital and R&D to create sustainable and long-term revenue growth, accelerating our profitability, and reducing our outstanding debt. We have never been in a stronger financial position, and I am excited for how this sets us up for a very bright future. Operator, we are now ready for your questions.

Thank you. We will now begin the question-and-answer session. [Operator Instructions] Our first question comes from Steven Seedhouse from Cantor. Please go ahead.

Good morning. Thanks so much for taking the question. Just looking ahead to another potential tailwind for ORLADEYO, which is the pediatric launch. Do you have a sense of how many pediatric HAE patients are on TAKHZYRO today in the U.S.? And do you think you'll mainly be switching children from TAKHZYRO, or can you sort of quantify how many patients maybe just don't want a needle, but would be new starts opportunities for ORLADEYO prophylaxis altogether.

Charlie, you want to take that one?

Sure. We certainly do expect pediatrics to be a tailwind for us. And just as a reminder, any future revenues for pediatrics are not included in our $800 million in the US or $1 billion global peak sales. To answer your question, I don't know exactly how much -- how many patients are on TAKHZYRO. We do think that there are about 500 patients, pediatric patients in the US, and at least 200 of whom could be appropriate for prophylactic therapy. But once an oral is available, we actually think that that could grow. And so I think our -- where we'll get patients is a mix of those switching from injectable therapies like TAKHZYRO, but we also think that the whole landscape for treating kids under age 12 could change and that more kids could start prophylaxis at a younger age to prevent attacks and really change the course of their life with the condition. And an oral therapy really makes that happen, because I would say there's literally no preference for an injectable for children. So we think we'll be very well positioned. We're excited about it.

Yes, I would add that when you consider that you can just sprinkle our medicine, the granules, onto some soft food or into a glass of water versus the trauma of sticking a needle into a toddler, we should be the market leader. There's no doubt in our minds that that's going to be the case. And I think the other thing that Charlie's referenced in the past is this halo effect. We still have some top HAE physicians that haven't started switching patients, and we know they have pediatric patients, and there's no reason for them to not start using our drug for pediatric patients. And when they see how well it works, our expectation is that, that's going to expand their usage. So we're really excited about this. We haven't put any hard numbers on it yet publicly, but we're really excited about it.

Great. Just also on DME programs, it looks like you're guiding forward data this year. I'd be just curious if you could frame what you would view as a successful outcome for that first readout, given the precedent data, given obviously the novel delivery method, just what are you hoping to see there in the first group of patients?

Yes. So we'll have our first patients on drug. As I said, we have authorization to proceed with enrolling patients in that trial. And what we're looking for is the obvious safety and tolerability, but more importantly to your question, we're looking for the effect on the thickness of the retina, the edema in the retina. So we'll be able to, in those first patients, watch over several months of exposure to assess that retinal thickness and whether that is changing. We do expect it will take a little bit of time to change, but not very long. And I point to some of our preclinical data that shows that in a VEGF-dependent model, the use of oral stat as a plasma kallikrein inhibitor has a result on leakage of the vessels very quickly within six days. So just to say that a readout that we'll be watching this year will be that retinal edema, retinal thickness, and will be observing in the first few patients by the end of the year.

Yes, normally we don't get super excited about SAD studies, but this is in patients. And what we've seen in rabbits is that when you give a single dose, you still have a really high concentration out to six months. So a single dose of this drug in DME patients could tell us a lot and so we're excited to see what we see at the end of the year.

Thanks so much.

You’re welcome

Thank you. Our next question comes from the line of Maury Raycroft from Jefferies. Please go ahead.

Hi. Good morning. Congrats on the update today, and thanks for taking my questions. I'm wondering if you could just talk more about getting patients on to pay drug and what you did there that worked better than expected and should we expect the rate to be maintained or improved upon going forward or what are some of the drivers you're focused on that could cause the rate to decrease again over time?

Sure, Maury. The number one thing that we did, and we've talked about this before, is we've, over the last couple of years, made investments in our team to make sure that we're really prepared and really expert in this reauthorization process. And we've gotten better every year, and we knew that there was this potential tailwind with Medicare this year. We also knew there was more space that we could improve in the very important commercial segment. And so, I would just say that the team has just reached a level of excellence that allowed them to execute this year. And we're looking forward to further improvements going forward. What we would expect the rest of this year is that, the rate will stay about the same, maybe decrease a little bit because the rest of the year our paid rate is driven more by new prescriptions as opposed to reauthorizations. But where we ended Q1, where we ended April becomes the floor for what I would expect in the future. And I'm very confident we'll reach our 85% goal. We'll reach it ahead of when we expected to originally. And we'll be looking to exceed it if we can.

Yes, the other thing I'd say is, you should take a look at that slide that Charlie referred to around the pattern of revenue this year, it's different, right? So we pulled forward revenue that would usually be a big bump from first quarter to second quarter into the first quarter, so you're going to see less of a bump. I think the other thing, though, that's exciting is that the underlying growth continues to be really strong. And so, that's where we're going to see incremental improvement over the course of the year, and we're really excited to share that with you.

Got it. That's helpful. And maybe just as a follow-up, if you could just provide more specifics on what you did to improve gross to net in first quarter and what you're doing to better improve that over the course of the year as well.

Yes. So a couple things, Maury. One big, big impact was just the fact that we got so many more Medicare patients paid, and that changed the overall gross to net mix. The other thing is, the team's just been really focused at every little detail that can make a difference, such as how much co-payment assistance do we give to commercial patients? And we've made some adjustments there that have improved gross to net. So the team is being very disciplined, not just about getting patients to pay, helping new patients come on board, but the team is very focused on maximizing the opportunity in all segments. And so, I'm really pleased that we made that kind of a progress in the first quarter, and I think that will be durable through the rest of the year.

Got it. Okay, thanks for taking my questions.

Thank you. Your next question comes from Jessica Fye from JP Morgan. Please go ahead.

Hey, guys. Good morning. Thanks for taking the question. I was curious, more specific to the guidance bump for ORLADEYO, can you quantify how much of that increase is related to Part D redesign and a higher proportion of paid patients through that kind of mechanism versus higher than expected demand, versus just execution dealing with the coverage re-offs at the start of the year. And second question, just with profitability pulled forward here, how does that impact how you think about investing in the business? And I guess, more specifically, could that allow you to accelerate any development plans for your earlier stage pipeline? Thank you.

I can take the first part of that. As I mentioned in my remarks, of the 10% improvement in paid rate, about two-thirds of that was related to the IRA helping patients afford their co-pay. So that's great. But what I'm really excited about is, how much progress we made in the 60% of patients who are in commercial insurance, where we improved by close to 5% over where we ended last year, ending up at 84%. So that was the other third of that improvement. Clearly, in terms of raising our guidance for the year, that increase in paid rate overall was the number one factor. But we have an underlying patient growth year-over-year, close to 20%. And as I mentioned, we had one of our best years ever last year, and in the first quarter we were a little bit better than that. And so, that underlying demand is what's going to drive this brand going forward. And then John, do you want to talk about that [Multiple Speakers]

Yes, I'll take the profitability. So yes, it's a territory we haven't been in before and are really excited to be in it. The programs are fully funded already to go as fast as we possibly can. And I think the teams have done a great job of figuring out how to get the programs to move as quickly as possible. And then in terms of what are reinvesting, I think we gave you a pretty good clue by paying -- making a pay down of $75 million of the Pharmakon debt. Cleaning up the balance sheet, not having to pay significant amounts of interest over time is something that, we'll continue to look at as cash flow comes into the company.

Operator, I think we can go to the next question.

Yes, thank you. The next question comes from the line of Brian Abrahams from RBC Capital Markets. Please go ahead.

Hi, everyone. This is [Nevin] (ph) for Brian. Congrats on the quarter and thanks for taking our questions. So just a following up from some of the prior questions. So given that you're on around 84% paid drugs. And also that you're on the lower end of your growths in net range for the year. Does this potentially indicate that there was a dip in the total patients that were on ORLADEYO and like how do you see that kind of evolving into the rest of the year?

Well, I can tell you there wasn't a dip in patients on ORLADEYO. So I'm maybe not quite understanding your question, Nevin. We've had extremely consistent demand. So, again, last year we had as many new patient starts as we did in the first year of the launch, and then we did a little bit better than that in the first quarter. The retention rate of patients has also been extremely consistent the last couple of years, where anybody who starts on ORLADEYO, we get about 60% of those patients to stay on therapy through the first year, and then very few drop off after that. So what we're seeing in patient demand is as strong, if not stronger than we've ever seen it. And then you add on top the paid rate and the improved gross to net. It just means that we're more profitable. And so, we still see reaching $1 billion in 2029, but the path to get there every year with that underlying demand is just going to be more profitable than we previously expected. So it's a great position to be in.

Yes, I think, Nevin, that I don't know if you're referring to that slide of the pattern of sales, which because of the fast change in free drug to paid, the pattern is different than previous years, and it'll probably go back to the same pattern as previous years next year, but there is nothing that is slowing down. And we're really excited about the underlying demand and continuing. And there's more patients to get, quite frankly. I mean, I think the last update Charlie said is around 3,000 patients.

3,000 at the end of last year.

Yes, and there's 10, 000 available, so there's plenty more to get. So no signs of slowing down. Just a change in pattern.

Got it. And then I guess on the uptick in patients that you're seeing for a preference for oral prophylactics, what do you think is kind of driving that underlying dynamic there? Have rates of maybe needle phobia changed or is it just a convenience factor that's being appreciated more as they kind of see the more maturing launch of ORLADEYO and the convenience that that offers?

Thanks for that question. I think what we've known since before launch that fundamentally the great majority of patients prefer oral therapy to injectable. But what's really important to patients is that, they get control of their HAE attacks. So they'll never sacrifice efficacy for convenience. But now four plus years into the launch, what they're seeing is with all of our efforts is with ORLADEYO, you can have both. You can have great efficacy. You can have convenience. And so the patients have seen it themselves. They've heard from their peers. It's a very connected community within HAE. And then their healthcare providers are just that much more confident, which always is a critical factor that the physicians have confidence in a drug. And so you put all this together with the efforts that we've made from a sales and marketing perspective. It's natural that patients' underlying preferences is coming out, and I think that's why we've seen it grow by about 20% over the last couple of years. And I -- I wouldn't be surprised if it continues to grow.

I think it was around a year ago we told you, Charlie told you that there was a momentum change and that there was a confidence buildup. And that was because more and more physicians were having positive experiences with their patients. Patients talk and doctors talk about other patients to their patients saying, I have a patient that does really well on ORLADEYO, you might want to consider trying it. And so, it's that confidence in the product that I think is reflected in the market research.

Great. Thank you all so much, and congrats again on the quarter.

Thank you.

Thank you. The next question comes from Stacy Ku from TD Cowen. Please go ahead.

Thanks so much for taking your questions and congratulations on the really impressive quarter. So first, as we think about these additional patient additions and strong patient demand, you've previously added around 60 prescribers per quarter. What are your expectations for this year? And then some follow-ups on Netherton. Are you able to make any disclosures on the Phase 1 early SAD-MAD results? Are you able to disclose anything at this point in time? Or can you narrow the timelines for any updates in Netherton? And then I have a follow-up on Netherton.

Okay, I'll start with the healthcare providers. Good memory, Stacy. Last year we actually averaged 61 new healthcare prescribers for ORLADEYO per quarter. It was 62 in 2023. And in Q1 we had 59. So it's incredible consistency at this stage in the launch that we're still convincing new prescribers. Our team will always go out and find new prescribers. The other thing though is, and John touched on this earlier, but we've made progress in the Tier 1 physicians. So 81% of those doctors have now prescribed and we're seeing more and more physicians become repeat prescribers and even some returning who prescribed some years ago now returning, now that they better understand the product. So the physician dynamics are excellent along with the overall patient dynamics.

And then Helen, you might want to talk about how we're thinking about packaging all the data towards the end of the year.

Yeah, so in terms of the results on the SAD-MAD, Stacy, we've been following that trial. We have -- its intent with initial safety and PK data. We have the confidence now from that to open the dosing in patients. So you should see that as a sign of generally what we're seeing. And then what's most important, and we've been clear about looking for the skin outcomes in patients. What's most important is what happens in patients. So we'll bundle it all together. It'll be by the end of the year. It will have the updates from the healthy volunteer data, but then more importantly, that outcome in patients, and are we at the dose that gets to skin healing.

So in healthy volunteers, no news is good news.

Okay, wonderful. Well, I guess that leads to my then follow-up about the Netherton. You talked about kind of the early interactions of investigators in the activations of sites, but maybe nuance Part 4 of the Phase 1 study. It sounds like you're getting at least some sense of safety. Could you broaden the POC in the younger patients or are you mainly staying into adults? Thank you.

So Part 4 is the extension of treatment. It is designed to serve additional patients. So what we're hearing at the sites, we're hearing clear enthusiasm. We're hearing that a potent KLK5 inhibitor that could target at the top of the cascade is something that physicians want to try in their patients with Netherton syndrome. It'll be the first few patients who are on that Part 3. And then we're sort of continuing, we'll open Part 4 and continue and broaden enrollment to get a longer term exposure. I would think of them as sort of going together rather than being separate. And the result is by the end of the year, we'll have patients on -- we think, both sections with a longer term follow up on those who've been dosed in Part 3 and then more recent follow up in those dosed in Part 4.

I think one other thing, Stacy, that I'm certainly learning as we learn more about this community and both the physicians and the patients is, there are some significant differences from HAE, right? There's no therapies in place. The organization for advocacy isn't nearly as advanced as HAE was. So those are challenges in finding patients. But the flip side is, the hope we're offering these patients is off the charts, right? They were hopeless, or they have been hopeless, and coping because they have nothing to treat the underlying cause of their disease. And when we start talking to patients and tell them what we're trying to work on, I mean, it brings them to tears. And so that's powerful. And so if we can find these patients, and I'm confident we will, and this drug gets to the skin, we've got something really powerful to help them and give them hope.

Wonderful. Thanks so much.

You're welcome.

Thank you. The next question comes from Gena Wang from Barclays. Please go ahead. Gena Wang, your line is unmuted. Please proceed with your question.

Thank you for taking my questions. I have two questions. I think that I joined a little bit late, so if already discussed, and I heard some of the answers, if already discussed, I apologize. So for your paid rate, truly very impressive, like 10% -- over 10% increase from the last quarter, 73.5%, now improved to 84%. You did a comment when you answered numerous questions, answered various parts, but can you help us understand what make it in such a short time that have such a big improvement? Can you walk us through the actual process where you did make it possible in short time to see such a high increase regarding the pay rate. And then the second question is regarding the DME. So you will have patient data later this year. Could you give us some benchmark you are looking for that you will consider that will be encouraging to move forward?

Yes. Hey Charlie, maybe I'll start first on this first one and then you can answer the rest. I want to remind everybody that when the Medicare negative thing happened, it snapped the other direction very quickly, like within a quarter. So this is a snap back, but I'll let Charlie explain it in more detail.

Yeah. So again, Gena, one thing I explained is about two-thirds of the improvement was Medicare. As John said, that was a quick snapback, but it was because our team prepared. And so the snapback is, and I've always said this, that Medicare plans approve ORLADEYO at the highest rate amongst all insurers that we see. It was just an affordability thing for patients. So it's great that the IRA is helping patients afford. And our paid rate amongst the 20% of Medicare -- of our patients who are in Medicare, is now 89%. So that kind of underlines what I just said about it being the top segment for approvals. The other piece, though, is the team really prepared on the commercial side. And one of the preparations is, we have all this long-term real-world evidence. So what we know about the drug and the efficacy today is very different from what we knew four years ago. And so, the team is able to use that more proactively with payers, and it's convincing more and more payers that this is a very effective drug, and therefore they're choosing to pay for it for the patients. That's where I think we can still make progress, but it's about the data, the preparation, and then also the intended impact of the IRA coming true.

The other thing before I turn it over to Helen on the DME is, back when patients were struggling to make their copay, we made a very conscious decision to give them free drug. And we kept patients and we actually gained patients as a result of that strategy. So then when the affordability got back to normal, those patients snapped back quickly. And I think strategically that was in hindsight a good move to me. Helen, you want to talk about DME?

Yes. So because we have authorization now to dose in patients, this is a big milestone for this program. We are looking this year to have exposure and experience with a few patients with that single dose. As John mentioned earlier, this is a drug with long durability of exposure. And we're looking for that the outcome, the retinal edema lessening, reduction in the size of the retinal thickness. We're looking for that, and we'll be looking for that for the end of the year. In terms of what then is the benchmark to move forward, we're looking for a really big effect. We're looking for a clear and uncontroversial reduction in edema that would then tell us that we have a dose level that's got the exposure necessary to have that effect. If we don't see that, we will increase the dose. So we'll either see a very significant reduction in edema and know that we have a dose we can take forward, or we'll not have to achieve that yet, and we'll expect to increase the dose until we do.

Yes, I think we've always said, we're looking for signals of activity and starting to get a sense around dose, and that's exactly what Helen said. When you have three patients per cohort, there's a limited amount of information that you can get, but I think if we can see some sort of effect and duration of effect that gives us encouragement, nobody else with a kallikrein inhibitor has done that yet, right? And so, that would be very exciting for the program.

Sorry, if I can follow up. So how many micron reduction you would consider clear and uncontroversial?

So I would use the, within the literature for what is generally accepted as something that's going to be predictive of likely response and visual acuity. I can't give you a number today, but I can tell you we're looking for an uncontroversial difference, so not something that's small.

Okay, thank you.

Thank you. Your next question comes from Laura Chico from Wedbush Securities. Please go ahead.

Good morning. Thanks very much for taking the questions. First one is just going back to the pediatric formulation for ORLADEYO. Can you just remind us on maybe some of the timelines after a pediatric launch arrives? Would there be a lag in deployment to the channel upon approval, just getting material out for supply? And then as we're thinking about the cadence of uptake in the pediatric population versus the adults, just kind of curious what dynamics we should be thinking about that might impact that uptake a little bit differently than what we've seen in the adults. And I have just one quick follow-up.

Sure. We will try to make the lag as small as possible. When we launched capsules back in 2020, it was only two weeks from approval to being in the channel. That was amazing. I don't know if we'll go quite that fast, but we're looking to get it out as quickly as possible. The other thing we'll do is prepare our team to begin promoting right away. And I think that's even more important, because it'll take a little time for kids to come in and visit their physician. The uptake dynamics, I alluded to some of this a little bit earlier. I think the biggest difference is that prophylaxis really hasn't been the standard of care for kids under 12. The historical conventional wisdom is that kids become symptomatic mainly around puberty. I think what we saw in our clinical trial is for many of these kids that is very not true. Many of these kids were -- in fact, I think the average age of symptoms was age two. And so changing the way that the whole treatment paradigm for children, if you could prevent attacks so that patients could avoid that fear, so parents could avoid that fear, it could really change the course of a kid's life living with HAE. And so I think that'll be the biggest change. And as Jon and I both said earlier, I think an oral formulation is going to be the natural choice for that starting prophylaxis with a kid. So we'll see how quickly it goes, but we're hearing a lot of enthusiasm from both healthcare providers and the patient community for the change that I'm describing.

Yes. And Laura, I'd add one thing. One of the things we learn with adults is, it takes longer than you think. And so that's why we're not getting out over our skis here on giving you guidance on the uptake, because we just don't know yet. We're confident that we will be the market leader because we believe we have a formulation that is way more acceptable to little kids than injectable. But the pattern to get there, it's just too early to predict.

Understood. Okay, thank you for that one. And then one quick follow up on Netherton. Can you remind us the dosing range you're going to be starting with for 17725? And then I just wanted to clarify, I know you mentioned advancing later to 12-week dosing, but what is the actual trigger for that? Is it dependent on occurring sufficient four-week data in the initial cohorts? Any clarity there would be helpful. Thank you.

Yeah, sure. So in terms of the dosing range, we have experience with a fairly broad dosing range now in healthy volunteers and we'll be dosing patients somewhere in the middle of that range. It's -- 8 milligrams is the dose for patients in that initial part of Part 3. There isn't a trigger so much for the Part 4, 12 weeks. It's more that we'll learn about the dose level, we'll learn about whether we see initial effects quickly in Part 3, and from that we'll understand if we need to start with the same dose or dose escalate quickly in Part 4. It's more that there'll be sort of dosing initially in Part 3, learning from that as we initiate Part 4, both going in parallel with ongoing observations over time. So as I said earlier, it's more like a continuous sort of set of two arms that go together.

Yeah, and if the drug works, we'll have an ability to keep patients on drugs.

I see. Okay. Thank you, guys. Congrats on the quarter.

Thank you.

Thank you. The next question comes from Liisa Bayko from Evercore ISI. Please go ahead.

Hi, there. Thanks for taking the question. Congratulations on a strong quarter. Two parts to my question. First is, I just want to make sure I understand that the paid rate improvement that you saw, you've talked about it kind of being like a switch that flips on. Is there any chance this flips back? Can you talk about the sustainability of this paid rate improvement as we head into next year and future years? And then part two is really, can you talk about the patients on treatment today? And then walk us through the kind of remaining pool of patients out there, at least in the U.S., who have not yet tried ORLADEYO and your plans to kind of increase utilization there. Thanks.

Sure. Thanks, Liisa. The paid rate, I believe, will be very sustainable based on the evidence that we've shown for ORLADEYO. It's really changing our conversations with payers. And so I think that 84% is kind of our new floors as we look forward over time. The patients on therapy, so as I mentioned earlier, at the end of last year, 3,000 patients in the U.S. had tried out of a pool of about 10,000. Launched to date, 52% of our patients have switched from other prophylaxis. About 30% -- just over 30% have switched from acute only and the remaining 16%, 18%, whatever it is, are patients, best we can tell, were naive to therapy. And so that last piece I'm excited about because what it shows is that this is a market that is still growing. We've known that the market for prophylaxis has been growing over time, but we're finding new patients out there and they're coming to prophylaxis. And so, we have at least another 7,000 or so patients who have not yet experienced ORLADEYO, and many of them will be appropriate for prophylaxis. You combine that with the 70% preference for oral prophylaxis that we discussed in the call today and the growing healthcare provider enthusiasm and the fact that we're getting paid at such a high rate, it just increases confidence overall and I think will continue to drive ORLADEYO going forward.

Yes, and if you think about it, if at the end of the fifth year since we got approval we're at about a third of the patients that have tried it and we're at $580 million to $600 million, We are definitely on our path to $1 billion.

Okay, great. Thank you so much.

You're welcome.

Thank you. The next question comes from Serge Belanger from Needham & Company. Please go ahead.

Hi, good morning, and congrats on the next quarter. A couple of ORLADEYO questions for Charlie. Now that you've reached your target for a paid rate of 85%. Should we expect continued improvements on that number? Is there more to do on the commercial or Medicare side? And then just to follow up on the patient add questions, sounds like 1Q was one of your best quarters ever in terms of new patient ads. Just curious if you're noticing a trend on where these patients are coming from. If it's still 50% pro-fee and 30% acute or is that mix changing with this new batch of new patient adds? Thanks.

Sure. Thanks, Serge. Yes, I think we're almost to our long-term goal of 85%, a little more room there. But what we'll do is, we'll probably up that number. We'll keep striving to get better. I mentioned just a minute ago that in the Medicare segment, that's 20% of our patients, the paid rate is now 89%. And so that shows that we can improve past the 85%. And we'll do everything we can to keep getting better. I don't expect another big tailwind like we had this year, but it's just now going to be incremental improvements. In the first quarter, yes, fundamentally the patient base was very similar to what we've seen since the beginning of launch. The other thing I'd add is, the mix of prescribers that I haven't completely discussed today, but in the first quarter, 55% of the prescriptions were from our top tier of doctors, those physicians that we know treat about 50% of all HAE patients. And then the other 45% came from everyone else. So really balanced across the board. I mentioned earlier, we had 59 new prescribers in the quarter. And so, we just keep capturing more opportunity and we keep capturing it from all the different segments, which gives us that extra confidence in the sustainability of this growth over the next several years.

Operator, we can go to the next question.

Perfect. Thank you. Your final question comes from Jon Wolleben from the Citizens. Please go ahead.

Hey, thanks for taking the questions. A couple on Netherton for me. Can you remind us of your preclinical tox work that you've completed so far? And then, Helen, when you talk about seeing a clinical impact, determining dosing higher, what metrics will you be looking at and what's your bar internally to determine whether or not you're in a sufficient spot in terms of efficacy?

Yeah, sure. So pre-clinical tox, so this is the biologic, it's protein therapeutic. There's a fairly standard safety profile for protein therapeutics and we're seeing a very consistent profile with that. I think the other thing to look at with preclinical talks is, we have the authorization now to proceed not only in healthy volunteers but also in patients, and that includes authorization in the U.S. and Australia. So just indicative of the range of confidence coming from the preclinical tox data.

Yes, and Helen, I would add we have an open IND and we have the ability to dose in Part 3 up to four weeks and Part 4 up to 12 weeks. So that gives you some sense of the duration of tox and the like.

Right, so standard toxicology to support that. In terms of the clinical impact, so what we're looking for is really normalization of the skin. That means, we're assessing by how the patient feels about their skin. Is there itch still? And we want to see the itch really go away. We're looking also at a physician assessment of the skin and the severity index for thickening and scaling of the skin. And so, we're looking for that redness to go down and for the scaling to stop. I expect that we'll see some of that initially. I expect that it will probably improve over time. And if we need to dose up to get to healing, meaning, normal looking skin and patient not reporting itch, then we'll dose up to that.

How many patients per cohort? Can patients in Part 3 be included in Part 4? And then how do you think about the time-dependent nature of these improvements?

So Part 3 is smaller than Part 4. We could see what we need to see in single digit patients, so it's going to be fewer than 10 in Part 3. Part 4 will be slightly larger, but it's still an ultra-rare disease and every patient will inform whether we're at the dose and seeing what we need. So it'll be larger, but not much larger in Part 4, maybe more than 10. In terms of the time dependency, we just don't know. We do know that we expect the skin turnover in Netherton syndrome to be about two weeks. We do know that we would expect healing to occur as the skin is turning over. So we may be seeing clinical signs as quickly as four or eight weeks in this. We also may be seeing continuing improvement and healing of the skin because the inflammatory components take a little bit longer to heal. But our goal is to see whether we are getting that initial quick result in the short term four or eight week timeframe after end of dosing and then observe over time as we continue to expand Part 4 and be able to dose patients for a longer period of time.

Super helpful. Thanks, Helen.

Thank you. This concludes our question-and-answer session. I would now like to turn the conference back over to Mr. Stonehouse for closing remarks.

Thank you. So, I mean, it was a great quarter. I don't know what else to say. And I am -- I'll repeat what I said earlier, I am immensely proud of the employees of BioCryst for delivering the results of this quarter. But count on us to continue to be executing. We're not going to rest on our laurels. There's a lot more to do, a lot more to deliver over the course of the year. And you can count on us for continuing to work as hard as we can to do that. So thank you for your interest and we'll keep you updated along the way. Have a great day.

The conference has now concluded. Thank you for attending today's presentation. You may now disconnect.