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Philina Lee

Thanks, Kate. In the first quarter, we achieved $149.4 million in AYVAKIT global net product revenues with $129.4 million in the US and $20 million ex-US. Our strong commercial execution drove revenue growth in what we expected to be a challenging quarter due to the typical Q1 financial headwinds inherent in our industry.
Let's walk through the headwinds and tailwinds. The short-term financial headwinds we've discussed previously played out as we expected, including typical first quarter insurance dynamics impacting gross to net and the impact of fewer ordering days. With our growing base of business, these factors can have a meaningful impact on a quarter.
As Kate mentioned, fundamental demand growth driven by a growing number of patients on therapy is a critical determinant of long-term revenue potential. This is the function of more patients starting and staying on therapy. We're pleased that Q1 met our expectations as we saw growth in new patient starts, both in the US and in our international business.
Discontinuation rates remained low, and we continue to see encouraging trends towards multi-year duration of therapy in both advanced SM and ISM. A key variable we were watching this quarter was our mix of free versus commercial goods, as we managed through the Q1 reauthorization process and monitored the impact of the Part D redesign and foundation funding availability.
This played out more favorably than we expected with our free goods rate now well below 10%. As a result of these favorable dynamics today, we are raising our guidance range to $700 million to $720 million for the year. We are exactly where we want to be at this point in the year, and we're well positioned to drive growth through the rest of 2025 and beyond.
We have a clear view of the SM opportunity in front of us as we move further down the path towards $2 billion in AYVAKIT revenue by 2030 and a $4 billion peak SM franchise opportunity. SM diagnoses are increasing globally, and with approximately 25,000 diagnosed SM patients in the US. We know we're in the early innings of market penetration.
Roughly 20% penetration of currently diagnosed patients in the US alone gets it to $2 billion in annual revenue. We expect to grow new patients starts through the end of the year and beyond. Of course, it all starts with the right medicine, AYVAKIT, an effective therapy with a broad label that addresses the root cause of disease and is also very well tolerated, enabling patients to start and stay on therapy over the long term.
Becker will discuss the growing body of evidence supporting AYVAKIT's long-term benefit in SM. In addition to AYVAKIT's compelling clinical profile, we know that what drives prescribing in this market is the powerful combination of an aware and ever-expanding educated prescriber base and an activated patient base, both recognizing the benefit and urgency to treat the root cause of disease with AYVAKIT now.
Let's start with prescribers. Since launch, we've been focused on increasing the breadth of our prescriber base through education and awareness. Driving awareness among allergy has been a key focus and is critical to long-term growth, as the providers managing the highest volume of SM patients are predominantly allergists.
A first experience with AYVAKIT predictably leads to broader use in more patients. So a growing foundation of experienced prescribers directly drives growth in the number of patients starting AYVAKIT over time, increasing market penetration. Since ISM approval, our prescriber base in the US has tripled with adoption split across academic and community site care.
Against the backdrop of a growing number of diagnosed patients, this creates an engine to drive growth in the number of patients prescribed AYVAKIT. What really catalyzes deepening of use over time are positive perceptions and experiences with AYVAKIT. Since ISM launched, we have conducted market research with over 700 providers.
Initial favorable perceptions of AYVAKIT from the PIONEER study results have grown even more positive with first-hand clinical experience and now with longer term data. Across all specialties, even dermatology and gastroenterology where we haven't yet started to deploy promotional effort, the vast majority of providers view AYVAKIT's profile as favorable.
Since launch, we've been targeting [hemocs] and allergists. Hemost treat less than a third of all ISM patients. We've talked about the importance of allergy for the long-term opportunity, and by expanding our call point to include derms and GIs, we will meaningfully increase the addressable patient pool.
Across these specialties, roughly 70% of the providers managing the highest volume of SM patients are allergists, derms, and GIs. This is why we're investing in expanding our field team to increase our reach and frequency where it matters most. Our field force expansion is designed to capitalize on where the majority of SM patients are treated.
We've just hired new team members who are onboarding and training. They bring a diverse set of experiences with an emphasis on allergy, dermatology and rare disease. They'll be in the field by the second half of this year, and I look forward to the growth they'll catalyze in 2026 and beyond.
AYVAKIT's positive reception among providers is matched by growing enthusiasm in the patient community. SM patients are highly engaged and active in their care decisions, and we're starting to see the clear impact of marketing efforts launched last year, including new direct-to-consumer and peer-to-peer programs.
Providers report that significantly more of their ISM patients are asking about AYVAKIT compared to last year. And once patients are on treatment, they have a very positive experience, with over 95% of patients saying they're highly satisfied with AYVAKIT as a treatment for their SM.
The SM market is highly promotionally sensitive, with the top two drivers being the efforts of our experienced sales team who are outperforming industry comps in promotional effectiveness scores and are direct to patient marketing efforts.
Our growing base of experienced prescribers, an increasingly engaged and activated patient base and the compelling profile of AYVAKIT put us in a great place to drive growth in 2025. But we're not just focused on this year. We are on the path to driving continued growth towards $2 billion in revenue by 2030 and are committed to continue to grow this market well into the next decade.
We plan to drive that growth by taking the same powerful combination of aware and educated prescribers with activated patients and amplifying it with a strategic investment in our field. We are confident in our multi-faceted approach to develop and capture this market.
I'll now hand the call over to Becker to share clinical updates across our portfolio.

Lemuel Hewes

Thanks, Philina. First, I want to talk about AYVAKIT's long-term data in systemic mastocytosis that we presented at quad AI and that Philina just referenced. What was remarkable in PIONEER is that the safety profile of AYVAKIT was superior to best supportive care at six months, a rare occurrence for an efficacious treatment.
Now, after three full years of treatment, we see the same safety profile. This is extraordinary in my experience. Generally, the safety profile becomes more complex over time. But for AYVAKIT, the frequency and severity of treatment-related adverse events have been consistent and remain low throughout three years.
And importantly, only 3% of patients discontinued due to treatment-related adverse events over this extended time frame. The 25 milligram dose of AYVAKIT provides an exceptional benefit risk profile for the vast majority of patients. In our real-world post-marketing experience, more than 90% of patients who start at 25 milligram stay at that dose.
The patients are highly compliant, satisfied and our discontinuation rates are very low. However, we know that there is a spectrum of disease severity in systemic mastocytosis, and a one dose fits all approach is not appropriate in this disease. The PIONEER study included patients with very high disease. We've enabled more severe patients to do escalate to 50 milligram in Part 3 of the study.
We recently presented data showing that these patients have had a safety profile consistent with that we've seen at 25 milligram. Efficacy continues to improve for PIONEER patients, as indicated by durable responses measured by TSF and quality of life measurements through three years.
Among the patient subsets and PIONEER who titrated their dose to 50 milligram, 93% of patients saw improved or stable TSF benefit at 50 milligram without any trade-off and safety. We're expanding our commercial and medical reach to an even larger target physician audience of allergists, dermatologists and gastroenterologists with multiple years of consistent data demonstrating that AYVAKIT is a safe and effective treatment in.
This helps drive comfort in trying a new therapy and prescribing AYVAKIT. Finally, we continue to advance the science of systemic mastocytosis in the HARBOR study of elenestinib. Our study design explores disease modifying measures of clinical benefit, notably the impact on bone health and recurrent anaphylaxis. These have been enthusiastically received by investigators, and they report also from patients interested in the study.
Turning now to our wild type kit inhibitor BLU-808. At quad AI this year, we presented data from the healthy volunteer study, and with this promising data in hand, we're moving into four proof-of-concept studies this year. We know that a strong safety profile is critical in the field of allergic disease. And with BLU-808, we have a wide therapeutic index to work within.
We're building in a range of flexible dose strategies across these studies, including consistent dosing, induce and maintain and titrate to effect, which we know is in line with how allergists treat. We've initiated our first two proof-of-concept studies, one in allergic rhinoconjunctivitis and one in chronic urticaria.
We will be initially testing doses between 1 and 6 milligram. This covers the IC-90 well and will allow us to examine a spectrum of biologic impact that ranges from calming or stopping mass cells from degranulating to killing them entirely. This will allow us to determine the impact on symptoms so that we can achieve the right balance of safety and efficacy for chronic treatment.
I'll start with chronic urticaria, where the role of mast cells as the key driver of disease is already well established. In our proof-of-concept study, we're using this indication to explore various dosing regimens for BLU-808.
Our initial 12-week Phase 2A study will include two key parts, an open label study of patients with chronic inducible urticaria and a randomized double-blind placebo-controlled study of patients with chronic spontaneous urticaria. Both parts will include multiple doses and dosing regimens.
Our goal is for BLU-808 to become an attractive oral option that achieves that balance of tolerability and efficacy and differentiates us from the rest of the field. Now, let me turn to the phase 2A study in allergic rhinoconjunctivitis.
We see this as a way to demonstrate the activity of BLU-808 in the respiratory tract. This is a 28 day placebo-controlled challenge study where patients are exposed to allergen, then treated with BLU-808 or placebo, and then re-exposed to compare their before and after treatment reaction.
Similar to chronic urticaria, in this study, we will assess multiple doses for safety, PK and clinical efficacy. We expect to have some early data by the end of this year in the [sindu] cohort. In the second half of the year, we planned to initiate studies in allergic asthma and in MCAS.
We discussed the role of the mast cells in allergic asthma at our webinar last year, and similarly planned to share Blueprint's approach to MCAS at our webinar on June 4 with Dr. Matt Giantti, the leading expert in mast cell diseases at the Brigham and Women's Hospital here in Boston. Results from these proof of concept studies will help guide BLU-808 development plans as we work towards improving the lives of patients with mast cell-driven diseases.
Now, I'll turn the call over to Mike.

Michael Landsittel

Thanks, Becker. Earlier this morning, we reported detailed financial results in our press release, and for today's call I'll touch on a few highlights. In the first quarter, we achieved total revenues of $149.4 million from net product sales of AYVAKIT.
Based on the positive fundamentals that Philina discussed, as well as the additional insight we gained around free goods in Q1, we are raising our AYVAKIT net product revenue guidance to $700 million to $720 million for the year.
Consistently strong fundamentals and continued growth in new patient starts in all markets will continue to drive performance through the remainder of the year. For our international business, the timing and outcome of ongoing pricing and reimbursement negotiations are another consideration.
Turning to operating expenses, we observed an incremental quarter over quarter increase in R&D expenses related to elenestinib and BLU-808 clinical studies. SG&A expenses were flat in the first quarter relative to the prior quarter, and we anticipate that we will see continued modest increases in both R&D and SG&A expenses as we invest in our priority pipeline programs, as well as increase investment in our sales and marketing efforts for AYVAKIT, as Philina spoke to in detail earlier on the call.
We continue to expect that our operating cash burn will decline significantly on an annual basis. To reinforce what Kate said earlier in the call, we are in an incredible position of strength today, particularly when you consider the macroeconomic environment. We have strong and consistent topline revenue growth driven by global sales of AYVAKIT.
The ability to continue to invest in innovation to drive future growth and a strong and durable cash position of $900 million. Our commercial and financial profile stands out among biotech as a positive differentiator, and now more than ever before, we are in a position of incredible strength to drive sustained growth for the long term.
With that, I'll turn the call back over to the operator for questions. Operator?

Question and Answer Session

Operator

(Operator Instructions) Marc Frahm, TD Cowen.

Marc Frahm

Hey. Thanks for taking my questions. First, on the commercial side, can you frame the type of rebound growth or acceleration of growth you might see in Q2, given the fact that the free goods is already so low, which maybe limit some of the typical Q1 to Q2 rebounds that we see that we see across the industry.
And then on the R&D side, for the 808, just talk to the strategy on the dose selections that you put into those. Are the two doses supposed to really test that intermediate range with the titration, or are you trying to maybe with the top dose really show the full power of 808 and inability to get close to it not matching the antibodies?

Kathryn Haviland

Yeah. Thanks, Marc, for that question. Maybe Christy, if you want to talk a little bit about how we've considered the fundamental growth and the drivers of demand and as we think through the year and then maybe to please add color, Becker, you can add into the question.

Christina Rossi

Sure. Hey, Marc. So if we think about the year, we obviously updated guidance. And so, if I think about the remaining three quarters, I would certainly think about the guide and that guide does imply growth, which is really what we expected when we set guidance at the beginning of the year as well.
We always knew that Q1 was going to be challenging for all of the reasons that Philina said, but what we expected to see was strong underlying growth in terms of those drivers of the longer-term potential for AYVAKIT, which includes patients starting, persistence duration, et cetera.
And so, that's exactly what we've see and that's played out in line with our expectations. And so, if you play that forward through the year, we would expect to see growth in the remaining quarters. The one wrinkle we saw in Q1 around a shorter quarter from an ordering perspective, I believe, if I'm not mistaken, it's made up actually in Q3, interestingly enough, but we definitely expect to see nice steady growth as we go through the remainder of the year.

Kathryn Haviland

Let's say, in our results this year, really our big card flip in Q1 was around how we're going to see free goods play through. And I don't know, Philina, do you want to talk a little bit more about that.

Philina Lee

Yeah. As we entered the year, I think one of the biggest variables that we had that informed our guidance range was that we had a large book of business, i.e., a really large number of patients, and we didn't know to what extent these patients would be able to transition and access paid versus free goods.
Over the course of Q1, like this is a big variable that has been tremendously de-risked and that has been one of the key drivers for our guidance update together with the expected growth in the underlying fundamentals, i.e., growth in patients on therapy as Christy just said.
So I think at this point thinking about the free goods trends, looking for the rest of the year, certainly, the range has narrowed. We have a better sense of the range to expect. We're below 10%. We don't expect this to really be able to go appreciably down further.
And really over the rest of the year, we'll need to be watching as new Medicare patients come on therapy, their ability to access commercial versus free drug, but I would just take it back to the trajectory that we're seeing in Q1 we firmly believe puts us on pace for our guidance as well as marching towards that $2 billion by 2030.

Kathryn Haviland

Becker, do you want to talk about the second question?

Lemuel Hewes

Sure. Let me talk about the dose range of BLU-808 and how we selected this and what our strategy is here. Just a reminder that we do have all three regimens, one which is consistent dosing, the other which is an induce and maintain, which will look at speed to symptom resolution and then our ability with a lower dose to maintain that symptom resolution.
And then one where will allow titration to the effect. And I think it's important to remember that in many diseases, including chronic urticaria, there are a multitude of symptoms. And really driving the relief of the patient at the right dose is what we're exploring, and we're doing it in a way that the antibodies really can't do.
So we're going to better understand the biology of the disease and the response with respect to the symptomatology as we use these different dosing strategies. And the intent of the study is to really set things up for the next phase of studies in chronic urticaria and in other indications where we get the optimized dosing for each of these indications.
As we said earlier, the 1 to 6 milligrams gives us a range that covers the IC-90 well, and we all mass cells don't die at once. And so, we'll look at different levels of killing in different patients to better understand killing dose and a dose that's designed to calm down the mast cells.
With respect to comparisons, again, these studies are designed to help us understand how to use the drug, and then to understand the full efficacy in the next wave of studies, we will bring that optimized dosing into a more definitive study.

Operator

Laura Prendergast, Raymond James.

Laura Prendergast

Hey, guys. Congrats on the progress of this quarter. Just may be to reiterate that question, what exactly have you guys baked into the guidance, any expected seasonality, EU contribution, any specific tailwinds or headwinds on new starts that you expect?
And then, just if you guys could comment on Part 2 HARBOR data, when should we expect that and is any elenestinib data priced into the $2 billion by 2030 -- the $2 billion by 2030, is that pricing in elenestinib and being on the market? Thank you.

Kathryn Haviland

Thanks, Laura. Just a reminder, everybody, let's try to keep it to one question just given the number of people we have in the queue, but we'll try to handle some other things offline if we can. Maybe Christy, will you take the guidance question and then Becker, we can talk about Part 2 HARBOR.
I can just clarify right away there's nothing from an elenestinib perspective in the $2 billion by 2030, that's completely driven by AYVAKIT, and we expect AYVAKIT to grow beyond that to be honest. So just so I can take that one. Christy, do you want to talk about guidance?

Christina Rossi

Sure. So the factors that we think about with guidance are very much consistent with how we framed it at the beginning of the year. Actually, we talked about it last year, right? So the two biggest determinants in my mind of AYVAKIT getting to $2 billion by 2030 and the $4 billion opportunity we see across the SM franchise over time is really treating more patients, right?
So having patients start on therapy and having them continue to stay on therapy. So those are the two big drivers, and we expect to see growth in new patients starts as they go through the year based on our expanding breadth and depth of prescribing that we're seeing in the US, and increasingly activated patient base, et cetera.
This is obviously still in the context of our disease market. You're going to see fluctuations there, but the overall trend line is clear and positive. We expect to see strength and duration of therapy as patients are staying on therapy for, we think, three years-plus potentially multiple years here.
And so, those are two of the most important variables as we go over time. Then there's a number of other things that actually may have more impact in the short term. And so, we think about gross to net, free goods rates, et cetera. And then of course our international business is coming along.
So those are (technical difficulty) Philina said, we had a major, I would say, card slip in the first quarter by understanding how a very large base of patients who are now on therapy as they went through the re-verification process, understanding how that free commercial mix was going to play out.
We knew it was going to be important, we knew that was going to be a big swing as we thought about top line revenue. And so, we're really pleased to see how that played out in the first quarter and also pleased to see continued strength along the other variables that we've mentioned that really again portend that longer term potential.
So those are still going to be the things that we'll continue to watch. There's ranges of outcomes on all of those variables but pleased to see that we were able to raise the guidance of Q1 performance and in terms of quarter-to-quarter performance.
We know our business. You talked about things like seasonality, et cetera. We've now far enough into this launch where I think we have a good sense of how these factors will play out in terms of impacting quarter to quarter revenue. We've baked that into the guide. And in fact, it baked it in when we started the year and expected Q1 to play out as it did.

Kathryn Haviland

Becker, do you want to talk a little bit about HARBOR -- obviously, we're just getting this up and running now.

Lemuel Hewes

So we're just starting this study. We have a highly motivated group of investigators and I'm hearing patients as well who are very interested in the study. As we see the evolution of the systemic mastocytosis in the world and we see how this study unfolds, we'll be able to keep you all more well informed about when we might see topline data, but I think it's premature to speculate at this point.

Operator

Michael Schmidt, Guggenheim.

Hey, this is Paul for Michael. Thanks for taking our question. Just on AYVAKIT, so for the ex-US, it looks like it was flat quarter on quarter. Can you just comment on what your overall expectations are for the international market drivers this year, including when ISM reimbursement beyond Germany could start to kick in.
And then maybe a quick follow up on those escalations that you mentioned in ISM patients. Your quad AI data suggested around a quarter escalated to 50 milligrams. What's your current visibility into what percentage of commercial patients have booked 50 for ISM? Thank you.

Kathryn Haviland

Yeah. Thanks for the question. And we'll start, Christy, you take international and then Philina, you talk a little bit about what we're seeing in dosing. One thing I should say is the international teams have just done a tremendous job and their year over year performance more than doubled from Q1 last year. So we're really excited about where we are. But you want to talk about the Q4 to Q1 dynamic, Christy?

Christina Rossi

Yeah. Absolutely. So right, as Kate said, the international team has been doing very well. We've talked about the fact that, if we think about this contributions to the topline, last year, we expected it to be in that 10% to 15% range.
This year, on a much bigger base we expect it to also be within the 10% to 15% range, right? So the international team continues to perform and we're seeing nice growth there. It's important to remember that Germany is the only ex-US market with ISM reimbursement at this point.
We do expect some others to come online through the year, but we'll really start to see ISM growth across a number of markets as we head even into next year and beyond. The business in Germany is doing quite well. We're continuing to see trends that look very similar to the US, which has been really encouraging to see.
So nice growth and patients being treated, very similar trends in terms of uptake. Fluctuations can happen quarter to quarter. There were some things between Q4 and Q1, for example, like timing of distributor orders which can be lumpy, a little bit of FX at the beginning of the year.
We're still talking about a relatively small revenue base relative to the US, right? So these little factors can obviously have a role when we look at Q1 and we've seen that before if you go back and look at international performance over the last year or so. But the bigger picture is that business is doing well, German launch is doing really well, and we're looking ahead and looking forward to having some other ISM launches come online.

Philina Lee

And so, the question on dosing, the 25 mg benefit risk profile continues to serve the vast majority of patients very well. It's under 10% of patients that we're seeing who may dose escalate to 50 mgs over time, and this is occurring against the backdrop of the profile of the 25 mg holding strong and improving with continued long term efficacy and safety outcomes. We also see this reflected in just the really positive sentiment for AYVAKIT reflected in both our provider and patient satisfaction.

Kathryn Haviland

And just one thing to add to that is that even what Becker showed you from both the safety and efficacy of the 50 mgs is that what we see is that with AYVAKIT, at 25 milligrams or 50 milligrams, patients don't have to weigh a trade-off between efficacy and safety.
And they can experience a very low treatment burden that really allows them to just get back to their lives and with a medicine that really empowers them to live and do the things they want to do. So both the 25 and 50 have really come through in a very nice way for these patients.

Lemuel Hewes

And the other thing to remember is that the PIONEER population was a highly advanced patient population, enrolled in the middle of a pandemic, first study out there with a really effective therapy. And so, it's probably not indicative of what will be seen in the real world.

Operator

Michael Yee, Jefferies.

Michael Yee

Thanks. Good morning. Congrats on the continued growth. I'm thinking about growth for the rest of the year. I know you've gotten a bunch of questions about headwinds and tailwinds and different dynamics. Can you help give some color as to perhaps the trajectory or shape of the curve in Q2, 3, 4?
Is it consistent year over year growth in each quarter? Are there different things that impacted those quarters and as part of that perhaps even OUS given that it appeared to be more flattish and just wondering if that's a factor as well into any of these quarters for the rest of the year. Thank you.

Kathryn Haviland

Thanks, Michael. So I think what you're asking is how to think about the remainder of the year. Obviously, we're really focused here on how we're exiting the year because that is what really drives us to that laser focus on that $2 billion by 2030 but understand that you guys want to get a sense of how we're thinking about the quarters. I don't know, Mike, if you want to provide a little bit color and how do you think about that.

Michael Landsittel

Yeah. I'll start. I mean, I think what's most important is to put this in the frame of what our updated overall annual guidance is and using that like that's the benchmark that we're guiding too. And as we've talked about before, like each quarter can have unique variables in the US and international.
I think the one thing that Christy mentioned that we did want to point to if you think about like the growth especially over like Q2, Q3, it's like we've talked about we've missed an order day in Q1, right? That actually gets made up in Q3 in the calendar and just for context like our biggest customers tend to order on the same day each week.
We had one less of those in Q1. It gets made up in Q3. So right there you're going to see a differential dynamic between Q2 and Q3, where you'd say there's probably a little bit more, shifted into the Q3 period, but fundamentally I just point to consistent underlying patient growth, and that's been as expected and we continue to drive towards that as we go for the updated guidance range.

Operator

Colleen Kusy, Baird.

Colleen Kusy

Great. Good morning. Thanks for taking our questions and congrats on all the progress. One quick one from us for the growth this year. Can you talk to how much of that is driven by the newer specialties that you're going after in terms and GIs versus the allergist and hemocs that your first target prescribers?

Kathryn Haviland

Yeah. Thanks, Colleen. Philina, do want to talk about how you're thinking about the prescriber mix this year versus next year, I guess.

Philina Lee

Yeah. Thanks for the question. So I think as Christy started alluding to we expect growth -- we expect to drive increased treatment rates and growth in the number of patients on therapy. We have a strong engine in place to do this already with what we've established across our target specialties and an increasingly activated patient base.
So I would say a primary driver for growth over the course of this year is really that activated prescriber base and our ability to both grow and expand that as well as deepen it over time. Our chart shows -- we understand very well the dynamics of how a first patient starts and then a positive experience leads to growth and deepening over time.
Secondly, we see more and more patients coming in and asking about AYVAKIT, showing that our direct to patient efforts are really working and we expect this to also capitalize growth over the course of this year. As we shift into the newer specialties, we think this will enable us to further amplify these efforts.
There's really an untapped opportunity of additional SM patients who are being seen by derms and gastros. I think what we've learned from this market is hemocs alone are only about a third of the opportunities. So we know it's important to expand.
Our objectives with derms and gastros are really the ability to move these patients towards treatment, whether or not they're literally the prescribers at the outset, but they can also refer to our very strong and and growing prescriber base. And we expect this to further catalyze growth really in 2026 and beyond.

Kathryn Haviland

So just for clarity, we really do expect our primary prescriber base to be that growing base of allergists. Our stable base of the hemocs group, which sees the minority or the smaller group of patients. And then the growth into GIs and derms will really be 2026.

Operator

Derek Archila, Wells Fargo.

Derek Archila

Hey. Good morning, and thanks for taking the questions. I just want to understand how durable a 10% free drug rate is. And I wonder if you could characterize how the patient adds have trended in April relative to IQ. Thanks.

Kathryn Haviland

So Derek, we don't really talk about the ongoing quarter, but we can certainly talk about how our view of the durability of the free patient goods rate. And just to know, it's actually well below 10% at this point. So Philina, do you want to talk a little bit about how you're thinking about that for the rest of the year, the free goods rate?

Philina Lee

Yeah. I think what we're really emphasizing is we've de-risked. We've majorly de-risked the variable of free goods by just moving this big base of patients. This large number of patients have been able to access commercial therapy in Q1, and that's been due to the availability of foundation funding, the ability of patients to navigate the new smoothing process.
And so, we also feel like with this type of floor -- well, there's probably not room for this to further improve, but we expect that rate to remain relatively durable over the course of the year. Now, of course, what we'll be watching is as new Medicare patients come on, how able will they be to access commercial therapy, and that depends on factors like how long will foundation funding continue to be available as well.
But I would say, it's the de-risking of the patients who have already moved, which has led to a more favorable than expected upside. That's one of the key factors in our updated guidance range. But really, it's the underlying fundamentals that we expect continued growth in patient starts and patients on therapy that we expect to grow throughout the course of the year.

Operator

Salveen Richter, Goldman Sachs.

Hey. Good morning. This is Mark on for Salveen. Thanks so much for taking our question. You guys mentioned you may show 808 data from the POC studies in Sindu this year. In your view, what is the bar for 808 and Sindu and also in allergic rhinoconjunctivitis, and how do you think this will compare to the antibodies here?

Lemuel Hewes

Yeah. In terms of the cadence of the data, we're going to need to see how the enrollment goes and there is a relatively rare form of the disease, and we'll update you all as we know more about how the enrollment's going.
And as I stated earlier in terms of the bar, I think they're going to have to stay tuned to over time to really understand the full efficacy of 808 in these diseases because what we're really trying to do is learn the optimization of the regimen and which symptoms matter most to the patients and how quickly we can resolve these with various testing regimens of 808.

Kathryn Haviland

I think for the allergic ARC study, again, we're watching enrollment there. The study is up and running and again, we hope to have some data by the end of the year and we'll keep you guys posted on both of those as we continue to execute those programs.

Operator

Brian Cheng, JPMorgan.

Brian Cheng

Hey, guys. Thanks for taking my question. Can you elaborate a little bit more on the drivers behind the flat growth ex-US this quarter? It's a flat growth there, driven partly by the negotiated price. Thank you.

Kathryn Haviland

Thanks, Brian. I think as Christy was mentioning, the underlying fundamental growth in terms of growing patient starts and keeping patients on therapy was exactly where we expected it internationally. As Christy had mentioned, we do get some lumpiness in terms of our distributor markets in particular, and there was some pull forward ordering in those markets in Q4 that really just influenced the dynamics between Q4 and Q1.
I think what's most important is that the international growth year over year nearly doubled. And as Christie mentioned, we're just in one -- we're just in Germany right now in ISM, and we're going to have more of the larger markets coming in line this year. And so, it's flat from a revenue perspective, it's certainly not flat growth from an underlying fundamental demand perspective.

Operator

Reni Benjamin, Citizens.

Reni Benjamin

Hey. Thanks, guys for taking the questions and congratulations on the quarter and the raise of guidance. I'd love to just learn a little bit more about the metrics you guys used to gauge, maybe the success and failure of the DTC advertising strategy. Those tend to be quite costly and I'm curious as to how you evaluate that.
And I think, Philina, you mentioned that there'll be promotional efforts that you're going to employ the dermatologists and gastroenterologists. Wanted to see how big that physician pool was and whether this would increase the total pool of diagnosed patients or that 25,000 that you mentioned already is taking into account the dermatologists and gastroenterologists.

Kathryn Haviland

Yeah. Thanks, Ren. I mean, all DTC is not the same, and we certainly have a more targeted approach here, but Philina, do you want to talk a little bit about what we do from a DTC perspective and then also just the universe of additional specialties we're looking to target.

Philina Lee

Yeah. Absolutely. I would say that our direct to patient efforts are really focused on two things. The first is increasing the awareness of AYVAKIT as a new treatment option, and the second is really creating opportunities for patients to hear from the very positive experiences of other patients who have benefited from AYVAKIT.
And so, we use a lot of metrics. I think it really comes down to the growth in awareness in AYVAKIT non-users. Obviously, we've seen the number of users increase, but continue to drive the awareness of AYVAKIT using our direct-to-consumer adds.
We are, I think, importantly, executing on these initiatives in a highly targeted way for this rare disease market. And some of the, I think, most resounding method metrics we've seen is more patients going into offices asking about AYVAKIT as well as the growth that we're seeing in the patients who are starting.
To your question about dermatology and gastroenterology, I would say it's a bit of both things that you mentioned. The first is there's already an untapped opportunity of already diagnosed SM patients being treated by these additional specialties. And secondly, we would actually expect us to grow the treatment rates over time, which can lead to some of that longer term sustained growth.

Operator

Ami Fadia, Needham.

Ami Fadia

Hi. Good morning. Thanks for taking my question. If you think about the different buckets of physicians, the derm and gastros, the allergists and the hemos, can you give us a sense of what's the mix of the patients that are being treated by each specialty and maybe give us a sense of your penetration in terms of region frequency where you are today and then how you see that evolve with this expansion into the germs and gastros data this year. Thank you.

Kathryn Haviland

Philina, do you want to talk a little bit more about specialties?

Philina Lee

Yeah. So I'd say there are a number of SM patients being treated across all of these specialties today. It's our conviction the market opportunity that's really triggering us, I think, to invest in expanding the field force, which enables us to increase reach and frequency across the allergists and hemocs where we've targeted primarily to date as well as expand into the derms and GIs.
I would say there's incredible headroom across all of these specialties to continue the growth. Most of the prescribing to date has of course been in allergist and hemocs. One of the things we've been really pleased to see is that the growth of breadth of prescribing has actually been faster into allergy, and we know this is really important to capture that long term opportunity.
And again, for germs and GIs, we are just getting started, and we know that they are both treating an already diagnosed number of SM patients, but there are also patients coming in who can increase that diagnosis rate. They're presenting with cutaneous mastocytosis in the dermatology offices or things like IBS with some other signal of systemic involvement in the GI office.

Kathryn Haviland

Maybe one thing I'll just add is that as we think about AYVAKIT, it really is the opportunity that the long term safety data that really lowers the bar as people think about the patients who are most -- who could really benefit from the treatment. And so, we all use these measures of TSF score and we try to classify patients as moderate, mild, severe, all these things, that's really a regulatory tool.
And what we see out in clinical care is it's about a patient and whether or not they are well controlled and whether or not they can do the things they want to do, go to work, participate in family events, and what we know is that a lot of patients who cannot across all of these specialties, and that's really the clinical context in a commercial setting that is very different than a context that we need for a regulatory approval.
And so, I think the fact that AYVAKIT is so well tolerated, we have three years now plus data really makes us believe this is the right moment to be continuing to expand an allergy and moving into GI and derms who we know will be very positively receive that that clinical long-term profile.

Operator

Peter Lawson, Barclays.

Hey. Good morning, it's Alex on Peter. Thanks for taking the question. Just a quick one on the new field force you've hired. Could you quantify that relative to the most recent or I guess existing salesforce? Thank you.

Kathryn Haviland

Philina, do you want to talk about the size increase.

Philina Lee

Yeah. So this is an incremental field force expansion that will enable us to both increase our reach and frequency on the current prescriber base as well as to expand to these other specialties. But importantly, we're able to do this in an incredibly targeted way, leveraging the strength of our analytics to know where patients are engaging most frequently across these specialties.
I think the key piece underlying all of this is like most of this market we can see resides outside of hematology. And so, this is an important lever for us to continue to drive growth in allergy as well as moving into other specialties.

Operator

David Dai, UBS.

David Dai

Great. Thanks for taking my questions. I just wanted to drill down on the prescriber base. Last year, you mentioned that as you're explaining to the dermatologist and the GI prescribers, how should we think about the compliance rate of these patients given that these patients could be moderate symptoms.

Kathryn Haviland

Yeah. That was a little bit to what I was mentioning is that it's the idea of milder symptoms is not really the pull through here, right? In a clinical care setting, it's patients who are just do not have enough control over whatever their symptoms may be to be able to do the things that they want to do in life.
And so, really in the commercial context that is the context. It's around is a patient well controlled or not. And so, the rubric of patients being more severe versus less severe across specialties is really not relevant for the commercial setting like it is for a clinical development setting.

Christina Rossi

The only thing I would add to that is that our commercial compliance across the board has been exceptionally high, which I think just speaks to the profile AYVAKIT once the patients makes the decision to start on therapy. We see patients doing really well. They're staying on therapy, they're highly compliant, and they're sticky.

Operator

Judah Frommer, Morgan Stanley.

Judah Frommer

Hi. Thanks for taking the question. Just to follow up on the urticaria indication for 808. I'd be curious how you're viewing unmet need in (inaudible) and CSU, whether the depicts an approval and CSU affects that, and whether risk benefit profile could be viewed differently by derms versus allergists. Thanks.

Lemuel Hewes

Hi. Yeah. So just first of all, I think that in most of these diseases having a small molecule daily oral solution is really what the patients are looking for. And so, we were pleased to see that (inaudible) had the activity that it did really helping everyone understand that this is a chronic inflammatory disease, but we still believe that addressing the mast cell directly, which is the driver of the disease is the right way to approach it. And that a small molecule will be the preferred solution.

Operator

Sudan Loganathan, Stephens.

Sudan Loganathan

Hi. Good morning. Thank you for taking my questions and congrats again on the sales results for AYVAKIT. My question is regards on the progress with elenestinib, BLU-808 and go to dominate your first protein degrader programs. Gow's your OpEx spend breakdown between the commercial and development programs prioritized? Is the profitability and free cash flow in the cards potentially this year? Or could we expect any of those earnings from AYVAKIT to be reinvested into the pipeline?

Kathryn Haviland

Mike, so you want to take that.

Michael Landsittel

Yeah. This is my thing. So I mean, as we've talked previously like capital allocation and prioritization has been one of our key priorities really over the last couple of years to make sure that we are investing in what we see are the greatest opportunities to drive topline growth both now with AYVAKIT and in the future with pipeline.
And so, we've been really disciplined on both being able to make sure that we're investing appropriately in AYVAKIT but also targeting within our pipeline where we think we have the greatest potential to drive growth.
So it's not so much like we're expecting to see modest increases as I mentioned in both SG&A spend and R&D because we'll be investing in both areas to drive again both near-term and long-term growth.
And I think, specifically, we don't typically break down like within the pipeline where that program spend is going, but clearly elenestinib and 808 are going to be the top priorities in the year term to drive that.

Kathryn Haviland

And one thing I would just add is that I think we have a really good track record here at Blueprint and in terms of our business development strategy. And I think we are very committed to maintaining a durable financial profile, making sure we're sustainable and able to invest in the highest -- prioritize drivers of growth.
And if there are programs that either we believe we would benefit from a partnership in terms of execution and or maybe not are our highest strategic priority, we have a track record of having outlicensed those and for instance, just recently, we put a program in the hands of IDRX and we just received $80 million at the beginning of this year due to that transaction and that was a program that we chose not to move forward ourselves but certainly was beneficial to move forward in someone else's hands.
So we will continue to look at using business development to enable us to first and foremost meet our corporate strategic interests and then secondly to make sure we're maintaining that really sustainable financial profile.

Operator

Thank you. That's all the questions we have time for today. Kate Haviland, I would send the call back over to you.

Kathryn Haviland

So thank you everybody. We are off to a very strong start here in 2025 with AYVAKIT firmly on the path to realizing its multi billion dollar peak opportunity. We're advancing our pipeline. We have the assets in place. We have the strategy in place to really achieve our goal of fundamentally shifting the way allergic inflammatory diseases are treated by targeting the mast cell. So we thank you all for your continued support of Blueprint Medicines, and we invite you to continue to follow our progress throughout this year.

Operator

Thank you. This concludes today's conference call. You may not disconnect.