Good morning. My name is Charlie, and I'll be your conference operator today. At this time, I'd like to welcome everyone to the Blueprint Medicines Second Quarter 2022 Financial Results Conference Call. All lines have been placed on mute to prevent any background noise. After the speaker's remarks, there will be a question and answer session. If you'd like to ask a question during this time, simply press star followed by the number one on your telephone keypad. If you'd like to withdraw your question, please press star followed by two. Please plan to limit yourself to one question. Thank you. Jenna Cohen, you may begin your conference. Thank you, Charlie. Good morning, everyone, and welcome to Blueprint Medicines' Second Quarter 2022 Financial and Operating Results Conference Call. This morning, we issued a press release which outlines the topics we plan to discuss today. You can access the press release as well as the slides that we'll be reviewing today by going to the investors section of our website at www.blueprintmedicines.com. Joining me on today's call are Kate Haviland, our Chief Executive Officer, who will discuss our successes in the second quarter and a look ahead to the second half of the year. Philina Lee, our Chief Commercial Officer, who will provide a commercial update. Becker Hewes, Chief Medical Officer, who will provide a clinical update. Christina Rossi, Chief Operating Officer, who will review our 2022 milestone progress and upcoming catalysts. Mike Landsittel, our Chief Financial Officer, who will review our second quarter 2022 financial results. Before we get started, I would like to remind everyone that statements we make on this conference call will include forward-looking statements. Actual events or results could differ materially from those expressed or implied by any forward-looking statements as a result of various risks, uncertainties and other factors, including those set forth in the Risk Factors section of SEC filings. In addition, any forward-looking statement made on this call represents our views only as of today and should not be relied upon as representing our views as of any subsequent date. Except as required by law, we specifically disclaim any obligation to update or revise any forward-looking statements. I'll now turn the call over to Kate. Kate? Thanks, Jenna, and good morning, everyone. Thank you for joining the call today. At Blueprint, we continue to build one of the world's leading precision therapy companies with a diversity of growth drivers across all stages of our business, including two globally commercialized revenue-generating medicines, multiple important clinical development programs across a range of prevalent and hard to treat cancers, a prolific early discovery engine and a strong cash position. Blueprint had a strong quarter with $36.5 million in total revenues, including $28.5 million in AYVAKIT net product revenues. The 20% AYVAKIT quarter-over-quarter revenue growth underscores the strength of our ongoing commercial launch as we continue to solidify AYVAKIT as a standard of care for the treatment of advanced systemic mastocytosis. Our launch in Advanced SM has demonstrated broad prescriber receptivity to AYVAKIT's clinical profile. Strong launch execution that has facilitated access and limited payer hurdles and an elevated patient awareness leading to increased diagnosis and treatment rates. It has also continued to improve our understanding of the non-advanced SM market and the significant opportunity AYVAKIT has to meet the medical needs of these patients. As we look to our registration-enabling PIONEER Part Two top-line data readout later this month. We ended the quarter with the announcement of a transformative $1.25 billion non-dilutive financing that ensures we have the resources and operational flexibility to drive Blueprint's long-term growth while maintaining our path to financial independence. This financing enables acceleration of our broad pipeline and an ability to continue to explore opportunities for synergistic and strategic business development. Business development has played a key role in Blueprint's value creation and long-term portfolio growth and has allowed us to fully realize the value of our prolific discovery platform. Today, we are happy to announce that we have outlicensed our internally discovered KIT exon 13 inhibitor to IDRx, a newly launched clinical-stage company. Christina will provide an overview of the transaction later during the call. Finally, we plan to provide additional insights into our breadth of growth drivers at our Investor Day, which will take place on November first of this year in New York City. We look forward to sharing our strategic vision for Blueprint with our near-term focus on the important growth opportunity in SM, as well as outlining how we are driving mid-term value through our EGFR mutant and CDK2 vulnerable cancer development programs, and how we're creating long-term value through our research, innovation, and vision. The depth and breadth of what we will cover at the Investor Day demonstrates our unique company profile and the strong position we have to continue to deliver significant value to patients and all of our other stakeholders. With that, let me turn the call over to Philina to discuss our commercial updates. Philina? Thank you, Kate, and good morning, everyone. Reflecting on our first full year of launch with AYVAKIT, I am most proud of the strong commercial execution our team has demonstrated as we deliver for patients living with advanced SM. We have established AYVAKIT as the standard of care in advanced SM, secured a strong and growing prescriber base, and enabled broad patient access with virtually no payer challenges. We have driven four straight quarters of double-digit revenue growth. In the second quarter, we continued to build on AYVAKIT's launch momentum, generating net product revenue of $28.5 million. Including $24.7 million in the U.S. and $3.8 million ex-U.S. Our launch in Germany is off to a strong start with early adoption at Mastocytosis Centers of Excellence as well as in the community setting. We're in the midst of country-specific reimbursement submissions in other key markets and anticipate launching in several more countries by the end of the year. Turning to the U.S., AYVAKIT is now the standard of care in patients being treated for their advanced SM with greater than 50% market share. It's the treatment of choice for more than 70% of patients who are starting on or switching to a new therapy. We expect both these measures to continue growing. We've now seen AYVAKIT prescriptions from nearly 300 accounts since the launch in advanced SM. Our team activated 46 first-time accounts in the second quarter, and we continue to drive breadth in the community setting and depth in the academic setting. Duration of therapy continues to trend favorably at about 18 months overall, and we expect many patients to benefit from AYVAKIT for even longer periods of time. The greatest opportunity we see to drive continued growth is to increase the proportion of patients who are being treated for their advanced SM, particularly SM-AHN, the most common subtype. Patients with SM-AHN have a poor prognosis, with a median overall survival of around two years. At EHA, we presented a retrospective study comparing overall survival for AYVAKIT versus best available therapies. Within SM-AHN patients, AYVAKIT demonstrated a median overall survival of 46.9 months versus 18.0 months for best available therapies. These data should further catalyze the urgency to treat these patients. Advanced SM represents just 5%-10% of all SM, and with our strong launch momentum, we're only just getting started. We see tremendous potential for AYVAKIT to benefit many more patients as we set our sights on the non-advanced SM opportunity. Non-advanced SM leads to debilitating and potentially life-threatening symptoms, including uncontrolled anaphylaxis, extreme fatigue, diarrhea, skin lesions, and brain fog. Patients and caregivers undertake a significant burden to manage the disease, avoiding everyday triggers and coordinating complex therapy regimens that in most cases fail to control the disease. There are no approved therapies today. Our goal is to transform the lives of patients living with this debilitating disease. Here's why we're excited about the opportunity. First, the number of diagnosed SM patients is steadily growing. We can see over 16,000 unique diagnosed SM patients in U.S. claims data, and most of these patients have non-advanced SM. This represents a remarkable 63% growth of the diagnosed patients in the U.S. since the initial launch of AYVAKIT in January 2020. Second, approximately 60% of non-advanced SM patients in these claims take complex regimens of prescription medications indicative of moderate to severe disease burden. These patients use a cocktail of symptom-directed therapies, including EpiPen, mast cell stabilizers, TKIs, and cytoreductive therapies. These complex regimens of off-label polypharmacy highlight the serious medical needs these patients face. Altogether, the claims data combined with a breadth of patient and provider research indicates an addressable market opportunity of approximately 7,500 non-advanced SM patients with moderate to severe disease today who may be candidates for AYVAKIT. This represents a significant patient population who have and will continue to actively seek treatment for their non-advanced SM. With a pricing strategy similar to rare disease analogs such as hereditary angioedema, we believe non-advanced SM may represent a multi-billion dollar opportunity for AYVAKIT. We expect the launch trajectory will follow other rare disease markets. We continue to advance our market development efforts, working with the SM patient and provider community to accelerate the time to diagnosis and initiation of treatment. We anticipate this will continue to increase the number of diagnosed patients towards the 32,000 prevalent SM patients living in the U.S. On a personal note, as I reach my eighth year at Blueprint Medicines, the non-advanced SM opportunity has never felt so tangible. We look forward to sharing more about this and how we'll capture this opportunity at our Investor Day in November. With that, I'll turn the call over to Becker to review our expectations for PIONEER Part Two top-line data. Thank you, Philina, and good morning, everybody. As you know, we plan to share top-line results from our pivotal study of AYVAKIT in non-advanced SM later this month. As the first registration-directed study in non-advanced systemic mastocytosis, PIONEER is on track to provide a wealth of data and confirm AYVAKIT's potential to transform treatment of this more prevalent form of SM. In June, we shared that the FDA requested we elevate mean change in total symptom score or TSS, which was previously a key secondary endpoint to become the primary endpoint. As we've seen with recent approvals of other medicines, this approach is increasingly becoming the FDA's standard for randomized trials designed to assess patient-reported outcomes because it considers the full range of benefits seen in each arm. Let's review our primary endpoint, the comparison of mean TSS reduction in each arm, and a key secondary endpoint, the proportion of patients who experience a response defined as a 30% reduction in TSS score. These endpoints are correlated as illustrated by the Part One data. Our primary endpoint, the comparison of group means, is a measure of how the population treated with AYVAKIT felt compared to those treated only with placebo plus best supportive care. We'll refer to the control arm as placebo-controlled for simplicity. As was the case in PIONEER Part One, patients in both arms continued to receive best supportive care before and during the study. In PIONEER Part One, we observed a 16.5-point difference between the two groups, which was correlated with 60% of AYVAKIT-treated patients experiencing a response, something placebo was not able to achieve for any patient. While this response was striking, we've received consistent feedback from practitioners that if at least one-third of patients treated with AYVAKIT responded, this would be highly important and practice-changing. Furthermore, both responders and those with less than a 30% reduction in total symptom score often experience profound improvement in their most severe symptoms, such as extensive rashes, persistent diarrhea, and brain fog, all symptoms that make normal life all but impossible. These reductions in most severe symptoms can often be life-changing for patients. We are confident that PIONEER Part Two, which is powered to measure a minimum difference of 7-10 points between TSS reduction, half the difference observed in Part One, will provide robust practice-changing results in all of these correlated measures of clinical benefit. In addition to the primary and this key secondary endpoint, and similar to our prior top-line data readouts, we will report top-line safety data. This will serve as the foundation for global regulatory submissions. It includes comparative safety from PIONEER Part Two, the first large placebo-controlled safety data set for AYVAKIT in systemic mastocytosis to date. I'm extremely enthusiastic about the promise AYVAKIT provides for thousands of patients who've been suffering from non-advanced SM for many years. I'll now turn the call over to Christina to review upcoming data milestones and catalysts. Thanks, Becker. Good morning, everyone. We've made significant progress against our corporate goals in the first two quarters of 2022, and we are looking ahead to a breadth of value-driving data catalysts planned for the second half of this year. Within our SM program, we plan to report PIONEER Part 2 top-line data later this month, as Becker shared, and initial clinical and safety data from the HARBOR trial of BLU-263 in non-advanced SM by the end of this year. We are also making rapid progress across our programs in EGFR-driven lung cancer, where we are working to generate data sets that inform further development and accelerate our path toward registration. At AACR in April, we presented early dose escalation and biomarker data for BLU-945 at once daily doses up to 200 mg. These data showed tolerability and initial proof of concept consistent with BLU-945's preclinical profile. Based on these data, we initiated development of BLU-945 in combination with osimertinib in the second quarter. We plan to report initial dose escalation data for the combination in the second half of the year with a focus on providing evidence that BLU-945 and osimertinib can be combined safely, as well as translational data highlighting the combination's broad coverage of primary and secondary EGFR mutations and early signs of clinical activity. We also expect to report a recommended phase II dose for single agent BLU-945 by the end of this year. More broadly and consistent with our prior guidance, we expect initial clinical data for BLU-701 in the second half of 2022 and for BLU-451 in the first half of 2023. Finally, we remain incredibly excited about BLU-222, our CDK2 program, and its potential to impact many patients suffering from highly prevalent cancers. We look forward to presenting initial clinical data in the first half of 2023. As Kate previewed earlier, we are proud to announce that we have out-licensed our internally discovered KIT exon 13 inhibitor to IDRx to advance the program into the clinic, evaluating it in combinations for patients with GIST. This represents our first development candidate of 2022. Because we believe in IDRx's focus on the combinability of precision therapies, we received a 15% series A preferred equity stake in exchange for our license grant. We are also eligible to receive up to $217 million in potential regulatory and sales-based milestones, as well as tiered royalties on net sales. This transaction is another example of our commitment to ensuring that valuable scientific and medical innovation reaches patients regardless of the shifts in our portfolio priorities. I'll now turn the call over to Mike to review our financial updates. Thanks, Christina. Earlier this morning, we reported detailed financial results in our press release. For today's call, I'll touch on a few highlights from the quarter. Total revenues were $36.5 million for the quarter, including $28.5 million in net product revenues from sales of AYVAKIT and $8 million in collaboration revenues. We are reiterating our previous revenue guidance for 2022 of $180 million-$200 million in total revenues and $115 million-$130 million in AYVAKIT net product revenues, putting us well on track to realizing the blockbuster potential for AYVAKIT. Our R&D expenses for the second quarter were $128.3 million, including approximately $10 million of non-cash stock-based compensation expense, reflecting planned growth in R&D expense related to the strong execution of our clinical trials. Compared to the first quarter of this year, R&D cost increased by approximately $25 million, driven by accelerated timing of expenses related to the startup and supply activities of four new clinical trials across our EGFR and CDK2 programs. Additionally, we saw increases driven by timing of certain early research activities. These investments in new programs will drive the next wave of value inflection points for Blueprint and highlight our ability to sustain meaningful innovation through our best-in-class discovery platform. SG&A expenses for the second quarter were $58.7 million, including approximately $15 million of non-cash stock-based compensation expense, and were flat compared to Q1 of this year. Looking forward, we expect that overall expenses will be flat or slightly lower in the second half of the year as we drive towards key data readouts. Finally, our June 30th announcement of a strategic non-dilutive financing agreement with Sixth Street and Royalty Pharma puts Blueprint Medicines in a strong financial position to drive rapid growth while ensuring our path to profitability in the coming years. As of June 30th, we had $947 million in cash on our balance sheet. This balance includes a $175 million upfront payment received under the Royalty Pharma agreement. In addition, in July, we received an additional $400 million in gross proceeds related to our agreement with Sixth Street, which will be recorded in our financial statements in the third quarter. This quarter was marked by executional excellence across our commercial, clinical, and research organizations. We continue to allocate resources towards R&D and core programs that are rapidly advancing towards value-driving milestones. The combination of our strong cash position with well over $1 billion on the balance sheet as of today, multiple drivers of top-line revenue, and diversity of important pipeline programs uniquely positions us to continue building a leading precision therapy company, bringing transformative medicines to patients worldwide and delivering value to our shareholders. I'll now turn the call over to the operator for questions. Operator? Thank you. At this time, I'd like to remind everyone, in order to ask a question, please press star followed by one on your telephone keypad. That's star followed by one on your telephone keypad now. Our first question comes from Marc Frahm of Cowen and Company. Marc, your line is now open. Thank you for taking the question. This is Ernie Rodriguez for Marc Frahm. Congratulations on a great quarter. I have two questions, if I may. Becker, you mentioned reporting the safety results for PIONEER, and I was wondering if you could tell us what level of granularity should we expect for the safety portion, and what would you see as an unacceptable number of intracranial hemorrhage or a placebo-adjusted neurocognitive AEs? Basically, at what level do you think these AEs could significantly affect adoption? A second question, if I may, for BLU-263, what should we expect for the initial data disclosure? What level of details, and how should we think about this data when comparing it to PIONEER? Thank you. Yeah. Thanks, Ernie. Hi. Becker, I think maybe you can start off with both, and then if Christina, you want to add to the BLU-263 comment, that'd be great. Yeah. For the top-line data, we plan to present adverse events and serious adverse events comparing the two arms, as we typically do with top-line data, when we first see the readout of these trials. With respect to expected rates of adverse events, I hesitate to speculate on what we would see in the trial. I think it's important to remember, though, that these are patients receiving standard of care medications, some of which have adverse events that overlap with the disease or even some that might overlap with some of the AYVAKIT adverse events. However, at 25 mg in Part One, we saw an extraordinarily good safety profile with very low rates of even grade one adverse events and really no grade three adverse events. We would expect the safety profile in Part Two to be very similar to what we saw in Part One. With respect to BLU-263, we have Part One of our study ongoing. The first part is blinded and placebo-controlled, as was the case with PIONEER Part One. We also have some patients that are in an open label portion of that study where we can look in an ongoing manner at adverse events and at reduction in TSS score. We expect to present some preliminary data about that trial during the quarter before the end of the year. We're looking at various opportunities to present the randomized Part 1 data. Okay. Thanks. Christina, do you want to add to this? Sure. Maybe just to add a couple of additional comments there. One, just on the safety hurdle for AYVAKIT. One thing that I think is really important for us to all keep in mind is that we have not actually seen a fully, you know, placebo-controlled safety data set for AYVAKIT yet. We are very much looking forward to having that data, and really understanding and contextualizing what safety looks like and benefit risk in the context of a randomized study where we haven't seen that data before. With regards to BLU-263, you know, as Becker said, we will have initial data prior to the end of the year, similar to what we saw from Part One of PIONEER. I think, you know, we're going to be looking at the data coming out of PIONEER Part Two, as well as this data to really understand how best to bring BLU-263 forward to patients. We know that the bar there is going to be incredibly high, and it's going to be set by what we anticipate will be, you know, really transformational data that AYVAKIT will be demonstrating in this disease. We really look forward to kind of putting those pieces together and then sharing more about how we see moving our best-in-class franchise forward from there. Perfect. Thank you. Our next question comes from Dane Leone of Raymond James. Dane, your line is now open. Please go ahead. Hi, thank you for taking the questions, and congratulations on the quarter and all the progress. I guess two really questions from me just to clarify some of the commentary from your presentation, that sparked some interest, I guess, from the investors on the call. The first one would be in your slide around advanced SM, your update on the market penetration of AYVAKIT seems to imply that you have about 50% share in the U.S. now. I guess maybe that's a bit below where we and others would think you would be at right now given the revenue run rate. If you could clarify, I guess what your U.S. expectations are for the opportunity in ASM, that would be helpful. Secondly, could you just clarify in terms of the pricing strategy, you did, as it relates to ISM mentioned you thought hereditary angioedema could be a comp, but that's obviously an incredibly highly priced drug. I guess some of the questions there are around, you know, use of omalizumab and, you know, other interventions, maybe off-label for ISM. Where's the conviction that you can price that high in ISM with AYVAKIT or 25 mg a day avapritinib? Thank you. Yeah. Thanks, Dane. Philina, maybe take both. The first question being the 50% market share feels low relative to the revenue run rate. You know, talking about the pricing assumptions. Yeah. Thanks for the question, Dane. First to your question about market share. Just first of all, confirming the way we are defining market share is the proportion of patients who are currently receiving AYVAKIT out of the total portion of patients being treated with TKIs and cytoreductive therapies. We have seen this steadily growing, and we're encouraged by this continued growth. Today, that number is over 50%. If anything, we're excited about the substantial headroom that this represents for the market, both in terms of the market share of treated patients. Even more broadly, we are continuing to grow the portion of the market that is actively being treated, and that's where we see the greatest amount of continued headroom for the advanced SM patient opportunity. To your second question about pricing strategy. I think that the intent was not to say that we were aiming for, you know, consistent or the same pricing as other hereditary angioedema therapies, but mainly to use that as a relevant analog for rare diseases where the underlying pathophysiology is known with high medical need, where you have medications that can enable disease modification and truly transformative benefits for patients. That is the type of transformative benefit that we anticipate for AYVAKIT. You referenced omalizumab, and I think it's really important to understand that it's in spite of these cocktails of symptom-directed medications, patients, the vast majority of patients still have substantial medical need. We've talked before about patient and provider burden of disease studies that indicate the majority of patients still talk about having to avoid leaving their home, because of SM, so that's about 2/3 of patients. 80% of patients, you know, despite taking these polypharmacy regimens, are reporting serious limitations in their work or daily activities. All of these mast cell-mediated therapies are only symptom-directed at the end of the day. We are really excited for the potential of AYVAKIT as a true targeted approach that addresses the underlying driver of disease to have disease-modifying impact. From what we've seen over the many hundreds of patients that have been treated over the past seven years on AYVAKIT is truly that ability to decrease measures of mast cell burden, improve symptoms, as well as quality of life. Perfect. As a reminder, if everyone can please plan to limit themselves to one question, that would be greatly appreciated. Thank you. Our next question comes from Salveen Richter of Goldman Sachs. Salveen, your line is now open. Hey, everyone. Thanks for taking our questions. This is Andrea on for Salveen. Maybe just one on the back of your data disclosures at EHA, or showing the benefit on overall survival. Just curious the feedback you've received there and how this is being marketed to physicians to drive further uptake. Thanks so much. Yeah. Becker, do you wanna start with the data from EHA and then others can chime in. Philina. Yeah. Just to remind you, at EHA, what we showed was an improved survival compared to standard of care treatment. We looked at patients that had been treated with cytoreductive therapies with midostaurin, and we looked at their overall survival, and then compared that to what we saw in our EXPLORER and PATHFINDER studies. We saw a substantial improvement in overall survival. What this has done is it's really solidified the notion that by driving rapid deep responses in this aggressive malignancy, we're able to achieve survival rates that have not been seen in this disease before. This has really in many ways woken up the community even further than the response rate has. People think about their patients as being very ill because they are, and they end up in the hospital repeatedly, and they are really quickly moving towards a survival event or potentially dying from the disease. The ability for a practitioner to stop this and provide additional life and also to see it in the depth of the response has been one that's been really embraced as we shared these data. Yeah, this is Philina. I'd love to add on to Becker's comment and share some of the sort of KOL and provider responses to this data. Treating physicians are truly excited about this data. They're talking about it as really first of its kind and practice-changing. As we have these discussions through medical interactions with the provider community, we are hearing feedback such as, you know, this illustrates we now have a treatment that can truly obliterate the SM. You know, beyond the surrogate measures of mast cell burden, we're actually seeing prognostic improvement in overall survival of these patients. A second piece is we think this is really important when it comes to that opportunity to increase the proportion of patients who are actively being treated for their SM. The greatest subset being patients with SM-AHN, where some providers had historically been used to prioritizing the AHN. Now seeing the important efficacy and safety data for AYVAKIT, the tolerability profile, as well as this emerging overall survival data, it truly shifts the balance towards the urgency to treat the SM. Thank you. Our next question comes from Peter Lawson of Barclays. Peter, your line is now open. Great. Thanks for taking my questions. Just in ASM, just what's the proportion of patients you're seeing that are naive to treatment versus already exposed to prior treatments? Proportion of revenues that you think are potentially off-label in the ISM space. Thank you. Philina, do you wanna take both of those? Yeah. Happy to. Thank you for those questions. We haven't provided specifics on the breakdown of patients who are treatment-naive versus switching from another therapy. However, I would say we do continue to see adoption across both of these patient populations. Importantly, we are seeing 70% of new therapy patient starts going to AYVAKIT, as well as 70% of switching from pre-existing therapies such as midostaurin. When you know, we're highly encouraged to see that data, and that essentially puts us towards a trajectory towards a market share of 70% or above. Your question about off-label treatment, certainly we don't promote to that. I would also say we are seeing a proportion of adoption coming from the non-advanced patient community, which is a reflection of the medical need that we see there. Maybe just to add on to that, a little bit of additional clarity. So as Philina said, you know, we don't break down specifically, but I will say the majority of our starts are, first of all, coming from what we would consider to be previously diagnosed patients. We still see a lot of headroom actually on both of those fronts. You know, a lot of opportunity to increase penetration of what we would consider to be prevalent patients, as well as to continue to see adoption for newly diagnosed patients. We have seen that increase, and we expect that to continue to increase. For non-advanced SM, as we've previously shared and as Philina just shared, we have seen from physician reports some utilization with those patients. It's very small, in terms of the proportion of our overall revenue. Certainly, you know, the vast majority of AYVAKIT revenue currently is coming from utilization in advanced SM. I do think, though, it's encouraging that we've seen prescriptions go through and be paid for for non-advanced patients as well, which I think speaks to some of the earlier questions around access and pricing. Thank you. Our next question comes from Reni Benjamin of JMP Securities. Reni, your line is now open. Great. Thanks for taking the questions and congrats on the quarter. Just sticking with PIONEER, you know, once you have the results in hand and you've submitted, do you expect a full approval from the FDA? Does this get a standard review or priority? Kind of just, as you think about the landscape, upon something like a full approval, do fast followers need to run a study against AYVAKIT or, you know, is this disease indication one where you can run other placebo-controlled trials? And if so, are there strategies that you have to keep the competitors kind of at bay? Thanks. Becker, maybe take the first part and I'm happy to weigh in on the second part or and we can, the team can as well. But With respect to what we would expect from this randomized placebo-controlled trial is we would expect this to be a full approval. Again, this is a supplemental NDA, and we do expect a rapid review of the dossier. With respect to what would be required for follow-on compounds, I think that and we thought about this quite a bit with BLU-263. We think that the bar is gonna be extraordinarily high with the AYVAKIT data that particularly given the clean safety profile and the high efficacy that we saw in part one. I hesitate to speculate on what the FDA will require, but we do think that coming behind avapritinib in indolent and non-advanced SM is gonna be a difficult lift for any compound. Just to add is to Becker's point, I think when you think about standard care standards as well, you know, we have cases where, you know, drugs with a similar mechanism are approved within a few months of each other. That's very different than when there's a multiple year gap, right? I think that is another kind of context to consider is just the temporal nature and what does a fast follower really mean. Thank you. Thank you. Our next question comes from Eun Yang of Jefferies. Eun, your line is now open. Thank you. Another question on PIONEER study expectations. In part one, you showed a 16.5-point difference with about 60% patients responding. In part two, it's a larger number of patient population. How do you think about the changes in effect size? Usually, you know, in the larger trial, effect size tends to decrease. Can you kind of talk about in this particular indication, whether you expect effect size to shrink significantly, or do you expect it's gonna be kind of similar to the data in part A? Thank you. Yeah. Becker, do you want to weigh in on that? Yeah. Thank you for the question. I appreciate the historical reference to phase III trials generally having a less therapeutic impact than what you might see in some early trials. However, in this case, I still expect very robust results. Part of the reason is that as investigators have learned about the patients, about the benefit of avapritinib, and about how to identify patients with very severe and moderate disease, we would expect the results to be relatively similar between part one and part two. Just another thing to remember about historical references is often people will change their design even slightly between the phase II and then the pivotal study. In this case, we've screened patients the same way. We've applied the same type of statistical analysis. Part one and part two are really quite mirror images of each other with just a broader investigator base and patient base. We expect the results to be quite robust and similar. Thank you. Our next question comes from Brad Canino of Stifel. Bradley, your line is now open. Good morning, and thanks for the refresher on market share versus market penetration. Quickly, I'd just like to ask, do you have an estimate on the U.S. penetration rate of disease-modifying therapies in ASM? Then a follow-up on Eun's question for ISM. Do you expect the degree of benefit in PIONEER from the new endpoint to impact physician utilization? You know, if the difference was 10 points between AYVAKIT and placebo, would you expect uptake to be significantly different than if it was a 15-point difference? Thank you. Maybe Philina, you want to take the first part of that question around market penetration, and then, Becker, if you want to weigh in on the second piece, and Christina can also add some color there. Yeah, thanks, Brad. Starting off, I think we shared in our last call that one of the things we're highly encouraged by is that the share of patients who are actively being treated for their therapy has grown substantially since the beginning of AYVAKIT launch. It's grown by about 40%. Now, an important point to the heart of your question is this is still a minority of patients with advanced SM today, and that flips into the opportunity where we see significant headroom to continue to increase the size of the advanced SM opportunity. Becker, maybe going to the kind of minimal clinically important difference and how you want to think about that relative to practice-changing impact on patients. Yeah. Let's talk a little bit about the endpoint switch, and then how investigators and prescribing physicians are seeing it. As we mentioned previously, the design of PIONEER and the ISM-SAF are the product of many years of collaboration with the FDA under the breakthrough therapy designation. Both the FDA and Blueprint are committed to measuring clinically meaningful benefit for patients in PIONEER part two. Just a reminder, the FDA requested the change in endpoint, elevating mean change to become our primary endpoint. Now just a little bit about the various endpoints. You have to remember that there are many ways to measure clinical meaningfulness in systemic mastocytosis. For patients, it's a return to a new normal after years of suffering from extensive rashes and diarrhea and pervasive brain fog, often preventing them from going to work. For providers, it also includes objective evidence that the disease burden is substantially reduced. As we've spoken to investigators and prescribers about this, they look at the totality of the data. Looking at individual patient responses, the proportion of patients that have different depth of response, the proportion of patients with resolution of each type of symptom. When their patient comes into the office, they can consider all of those, the benefits of AYVAKIT and consider what's right for their patient. They'll look at the tryptase, look at the allele burden. They'll look at the most bothersome or most severe symptom, and they'll go look at the results from PIONEER part two to understand what benefit their patients could attain. Yeah. I think, you know, just to add too that, you know, as we know for patients, and it struck me as we've talked to patients, kind of widely over the last, you know, number of months that we know that a meaningful change for a patient is one that really reduces the symptoms and often the most bothersome symptom that has changed their quality of life or their ability to work or to participate in kind of what we all take for granted as just normal activities of daily living. What we saw in part one is that AYVAKIT had a profound impact on the ability of patients to restore their quality of life, to get back to work, to be able to do the things that take vacations, things they hadn't done for years. To Becker's point, you know, it's of course, you know, we know that the 7-10-point change as we look at the part one data provides this type of meaningful benefit to patients. We are confident in that. Everything we've heard from both patients and providers reinforce that confidence that this will change the prognosis for these patients and change the practice in non-advanced SM. Our next question comes from David Nierengarten of Wedbush Securities. David, your line is now open. Hey, thanks for taking my question. Most of them have been asked, but I was curious. You mentioned a high bar for, you know, BLU-263 development, you know, assuming PIONEER is positive. I mean, is there a scenario where you know, discontinue development or would you consider is there a role for something like a molecule like 263 in maybe less severe, indolent mastocytosis and the mild to moderate version, I suppose? Or is there, you know, not a good way to slot that in? Thanks. Yeah, Dave, thanks for the question. I'll start and the team can add in. I mean, we are in incredibly strong position with two best-in-class assets that have slightly different profiles that we believe will both have a position both in SM as well as when we think about BLU-263 and other mast cell-driven disorders. You know, the data sets per, you know, the AYVAKIT and the clinical profile of AYVAKIT in advanced SM as well as what we anticipate coming out of PIONEER in non-advanced SM is how we talk about that's gonna be a very high bar for. We're gonna have to think about how to move BLU-263 forward. There are gonna be patients, whether that be less severely affected patients, or, you know, patients where the profile of BLU-263 is most appropriate and important. The position we are in is to be able to strategically develop the clinical evidence in those patient populations, as makes the most sense when we see, you know, the full set of clinical data out of PIONEER. You know, we have a first-in-class and best-in-class franchise in systemic mastocytosis and, you know, feel very excited about the opportunity to have a Blueprint solution for all patients with systemic mastocytosis, regardless of what form or subtype or clinical presentation they have. Thanks. Thank you. Our next question comes from Michael Ulz of Morgan Stanley. Michael, your line is now open. Please go ahead. Hey guys. Thanks for taking the question. Maybe a clarifying question first, just for the PIONEER top line results, should we expect both TSS score and responder analysis? Then secondly, just to follow up to some of the earlier discussion on sort of what's meaningful with respect to TSS. You mentioned you know, having a reduction in the most sort of severe symptom. Is there a particular reduction in terms of points on TSS, you know, that physicians would be looking for? You know, for example, is a one-point change enough, or do you need to have a couple point change there? Thanks. Maybe I'll just start with the first one. It's an easy question, and I'll let Becker answer the second. You can expect both the mean change in TSS as well as the responder analysis in TSS at top line. Becker, do you wanna weigh in on the you know, any specific domain point change? Yeah. When you look at a patient with a most severe symptom, it depends on where they're starting. There can be 1-2-point changes that are extraordinarily meaningful for patients and when you think about single digit changes, a 7-point change in something that's scored on a scale of 1-10 can be really substantial or even the disappearance of that symptom. If you can imagine a patient whose brain fog has been an 8, and that goes down by even 3 or 4 points, that could be a substantial change in their ability to function on a daily basis and go to work. For a rash, having it go from something that's very itchy and all over their body, which might be a seven or eight, and then dropping a few points on that single score, that can really be life-changing for a patient. We'll illustrate a lot of those scenarios as we get deeper into the data of PIONEER Part Two. I think it's gonna be transformative in so many different ways for different patients. Got it. Thank you. We will look forward to presenting those broader datasets at medical meetings, you know, coming up. We'll really, I mean, just as we, as Becker mentioned in the prepared remarks, this PIONEER study is gonna give us just a breadth and depth of data in this population, that, you know, that is kind of unprecedented, and we're gonna be able to really, you know, start elucidating all the dynamics within that dataset over time. Thank you. Our next question comes from Michael Schmidt with Guggenheim. Michael, your line is now open. Hey, this is Paul in for Michael. Thanks for taking our questions. Just had a quick follow-up on the ASM market. So for market penetration for new patient starts, you mentioned about 70% share currently. How much further room do you expect for growth at peak, and for treatment duration on 18 months, trending towards that direction? Does your current full year guidance for AYVAKIT incorporate any range of anticipated longer treatment duration? Thank you. Please, Philina, will you take this? Yep. Thanks for the questions, Paul. To your question about actually, would you mind repeating just the first part of your question one more time, please? Yeah. Just on the market penetration for new patients in ASM. You know... Got it. You mentioned about 70%... Yeah. ...share currently. Yeah. Yeah. Thanks for that question. Yes, we do see AYVAKIT selected 70% of the time for new patients. We do continue to see a significant amount of upside to grow the treatment of these new patients, as Christina alluded to. An important point is when we look at the market of treated, actively treated advanced SM patients today, we can see that over the past few years or so, it's only on the order of about 1,000 patients who have received active treatment with TKIs and cytoreductive therapies. When you combine that with our understanding of the prevalent patient population, on the order of about sort of, you know, mid-1,600 to 3,000 or so prevalent patients, you can see that substantial upside in the need to grow the proportion of patients who today has not yet been treated. That new patient share is an important source of growth and ongoing focus for our team. Your second question was around duration of therapy. We're highly encouraged as we continue along the launch trajectory of AYVAKIT to continue seeing significant durations of therapies in our patient trends. As I mentioned, we're trending towards 18 months, and we're seeing this consistently across both the academic and the community setting, which indicates a degree of physician comfort in managing patients across both settings. Can I just, I'll chime in a little bit to add some color there as well. To the first question, as Philina, you know, nicely summarized, we're thrilled to see, you know, really dominant market share at this point, right? AYVAKIT is clearly established as the best in class therapy amongst treated patients. That can increase above 70%. We know that not every single patient will be a candidate for AYVAKIT, right? Certainly patients with low platelets, et cetera. As we look at the opportunity to grow, you know, we see room to grow market share, but significant room to grow the size of the overall treated market. As you know, Philina was saying, some of the new data from EHA, et cetera, we think is gonna be really instrumental in driving that growth, and there is a lot of opportunity to continue to grow. With respect to duration, you know, we're very happy to see where we are. Trends and duration are not gonna be as relevant for guidance this year. They're certainly gonna be important as we think about the overall opportunity going forward. We're really excited because these long treatment durations should enable revenue acceleration as we get into, you know, sort of further years of the launch, and we start to see patients, you know, new patients sort of stacking on top of patients who have been on therapy for, you know, potentially quite significant lengths of time. Thank you. Our next question comes from David Lebowitz of Citi. David, your line is now open. Thank you very much for taking my question. Out of curiosity, when you look at the TSS score, I would assume that from the patient and physician perspective, not all of the symptoms are created equal as far as their impact on their treatment direction. Which of the symptoms are most typically cited as driving the treatment decision for these patients? Becker, do you want to weigh in there? Philina also, if you have any color from the interactions commercially. Yeah. David, that's a good question, and I had the same one when I first looked at the data, and I expected that maybe there would be a specific domain or a specific symptom that was driving a lot of the TSS reduction or maybe even more meaningful to patients. I really discovered the opposite. You know, if you are a patient with brain fog and you have been a practicing attorney and can't go to work anymore and can't function, then improving that brain fog is life-changing and extraordinarily meaningful for you. If you have diarrhea 20 times a day and you can't see your family, your friends, you don't have a social life, then improving the diarrhea can be really profound. You know, I've heard similar stories for each of the domains and each of the symptoms. The skin rash is one obviously that can be disfiguring and extraordinarily bothersome. It's very pruritic. I think we've all had allergic reactions, and we understand how life-changing that can be even for a day, much less day after day. We'll certainly dive more deeply into the various symptoms and the impact on TSS score in the rich data set that we're going to see from PIONEER. I've really been extraordinarily convinced that all of these symptoms, individually and combined, can be tremendously life-changing, and the disappearance thereof will really return these patients to what I've started to call the new normal. You hear so many stories about people saying, "I've never felt this good before," because they've been living with this disease for so long. Thank you for taking my question. Thank you. Our next question comes from Joel Beatty of Baird. Joel, your line is now open. Hi. Thanks for taking the question. For the top-line PIONEER readout later this month, do you anticipate breaking out results by each of the components of the TSS score? Then also to the last point where it sounds like patients are often able to reengage with kind of daily living and daily activities. Are there measures of that that you're collecting that you may be able to share at some point? Maybe I'll start, and then Becker, please, weigh in on the second. For top-line data, Joel, it would be very much the top line. The kind of endpoints that we've highlighted, as well as that top-line safety perspective. We will be planning to present this data at a medical conference in more detail, likely a few medical conferences in more detail in the near term after the top-line data. Becker, do you want to weigh in on the second part of Joel's question? Yeah. Yeah. Joel, we have multiple measures of quality of life that we will be digging deeply into during the filing and subsequently to show various ways of looking at the benefit, not only the measurable symptoms, but also the level of functioning and just the general quality of life that the patients have. Great. Thank you. Thank you, Joel. Our final question of the day comes from Matthew Biegler of Oppenheimer. Matthew, your line is now open. Oh, hey, guys. Thanks for squeezing me in. Maybe it's a controversial question, but given all the debate about the PRO endpoints, I'm just wondering if there's a scenario where you could leverage the breakthrough therapy designation to file for accelerated approval based just on improvements in objective endpoints. I'm really thinking back to GBT's story here in their development of Oxbryta, where they essentially shelved the PRO altogether and just filed based on those objective improvements. That would be an interesting case, but I'm curious to hear your thoughts. Thanks. Yeah. Thanks for the question, Matthew. I mean, really simply, I mean, we don't anticipate that scenario for us at all. I mean, this is a well-designed, registration-directed, global placebo-controlled study. You know, our belief will be that we have a data set that speaks for itself that is going to be registration-directed both here and in globally, and that we'll be looking for full approval. Thank you. There are no further questions at this time. Ms. Haviland, I turn the call back over to you. Thank you, operator, and thanks everybody for joining us today. As we discussed today, you know, at Blueprint Medicines, we are building a strong and resilient organization that will continue to drive value and growth, delivering transformative new medicines to patients around the world. Our ongoing global commercial launch success, the breadth and depth of our upcoming milestones and data catalysts, and our fortified cash position has us in a uniquely and exceptionally strong profile as we head into the second half of the year. We look forward to discussing the PIONEER Part Two top-line data with all of you later this month. Thank you for taking your time today and your continued support of Blueprint Medicines. Ladies and gentlemen, this concludes today's conference call. You may now disconnect your lines.