Ladies and gentlemen, thank you for standby. Once again, I would like to turn the floor over to Joey Perrone, Senior Vice President of Finance and Investor Relations. Please begin.

Thank you. Hello, everyone, and good afternoon. Welcome to Day One's first quarter financial and operating results conference call. Earlier today, we issued a press release, which outlines the topics we plan to discuss. You can access the press release and the slides to accompany this conference call on the Investors and Media section of our website at www.dayonebio.com. An audio webcast with the corresponding slides is also available on the website. Before we get started, I'd like to remind everyone that some of the statements that we make on this call and information presented in the slide deck include forward-looking statements as outlined on Slide 2. Actual events and results could differ materially from those expressed or implied by any forward-looking statements. We encourage you to review the various risks, uncertainties and other factors included in our most recent filings with the SEC and any other future filings that we may make with the SEC. These forward-looking statements are based on our current estimates and various assumptions and reflect management's intentions, beliefs, and expectations about future events, strategies, competition, products and product candidates, operating plans and performance. You are cautioned not to place any undue reliance on these forward-looking statements, and except as required by law, Day One disclaims any obligation to update such statements. Today, I'm joined by Dr. Jeremy Bender, Chief Executive Officer; Lauren Merendino, Chief Commercial Officer; Charles York, Chief Operating and Financial Officer; and Elly Barry, Chief Medical Officer. I will now turn the call over to Jeremy.

Thank you, Joey, and good afternoon. I'm excited to share that we achieved another quarter of growth and strong financial performance to start the year. I'm thrilled by the progress we have made thus far in bringing OJEMDA to patients in need. We continue to execute on the three priorities we laid out for our business in 2025 earlier this year. The first is establishing OJEMDA as the standard of care in second-line plus pediatric low-grade glioma and driving OJEMDA revenue growth. The second is advancing our clinical development pipeline for FIREFLY-2 and DAY301. And the third is further expanding our portfolio. In the first quarter of 2025, OJEMDA quarterly scripts increased to over 900, representing 16% growth over total scripts in the prior quarter. This growth drove net product revenue for OJEMDA to $30.5 million for Q1 2025. Our consistent growth each quarter since launch and the market dynamics we've observed over the past 12 months have further reinforced that OJEMDA is a foundational opportunity for Day One that will drive durable long-term value creation. Significant untapped potential remains for OJEMDA in relapsed/refractory pLGG. Prescriber adoption continues to increase, on-label patient demand has grown steadily, payer approval rates are high, and patients continue to experience longer treatment periods on OJEMDA as time progresses. All of these data points give us confidence that the steady increase in OJEMDA revenue will continue. Beyond OJEMDA's commercial performance, we remain focused on building value across our pipeline. We are encouraged by the enrollment progress we've observed in our global FIREFLY-2 confirmatory trial. We expect the trial will be fully enrolled in the first half of 2026 as we endeavor to drive expansion of OJEMDA beyond the relapsed/refractory pLGG approval and into the frontline pLGG setting. Additionally, our partner, Ipsen, recently announced that their application for tovorafenib was accepted by the EMA for review, bringing it one step closer to patients in that region who remain in need of a new treatment option. Our DAY301 program also continues to advance through the dose escalation portion of the Phase Ia trial. Our successful track record with OJEMDA has paved the way for us to continue to discover and develop first-in-class or best-in-class programs for both children and adults. We remain committed to and are actively evaluating business development opportunities that will allow us to expand our multi-program clinical stage portfolio aimed at driving sustained long-term growth. This is an exciting moment for Day One. 2025 is off to a great start. We have a solid financial foundation that provides us with multiple options for value creation in the coming quarters, even during a period when macroeconomic factors present existential challenges and uncertainties for many biotech companies. OJEMDA's launch continues to deliver solid growth, and I am proud of the progress we have established, with a clear path for long-term financial and program success for the company. I'll now turn the call over to Lauren to discuss our commercial progress in greater detail.

Thanks, Jeremy and good afternoon. OJEMDA is off to an excellent start in 2025. As Jeremy mentioned, we delivered $30.5 million in net product revenue in Q1. Our revenue is driven by the over 2,500 total prescriptions written since launch, underscoring both growing physician confidence and the critical role OJEMDA is beginning to play in the treatment landscape of pLGG. This is a substantial foundation of physician experience, from which we can grow in future quarters. Let's take a closer look at our revenue. Q1 marked another quarter of significant growth, with our team delivering 11% growth in US net product revenue quarter-over-quarter. We delivered well this quarter, despite some seasonality we observed in January. This was primarily due to the holidays impacting the timing of scans and initiating new treatments, which led to a slower start to the year. Since then, we have seen a rebound with April being one of the strongest months for new patient starts since launch. Our launch execution continues to deliver a significant impact. Cumulative US OJEMDA prescriptions grew to over 2,500 since launch, delivering 16% growth over the prior quarter. In addition to new patient starts, which we've already discussed, duration is also a key driver of our performance and we continue to see a high percentage of on-label patients continuing on therapy each month. This speaks to the tolerability of OJEMDA and the benefit patients and physicians are seeing with our product. Through continuing to expand both breadth and depth of prescribing and supporting physicians and patients during their time on OJEMDA, we continue to drive growth in total prescriptions. Our team at Day One continues to see and demonstrate a substantial market opportunity for OJEMDA. It can be complex to see the whole picture, so let's break down the growth potential that still lies ahead for our product. This slide summarizes the estimated number of relapsed/refractory pLGG patients being managed at each of our priority accounts. We've previously shared our estimate that in the US, there is a prevalent pool of approximately 26,000 relapsed or refractory BRAF-altered pLGG patients who have received at least one prior treatment. Based on PFS curves, we estimate that about half of these patients are likely in long-term remission and are not likely to need an additional systemic therapy. If we allocate the remaining patients proportionately across our priority groups and divide by the number of accounts in each priority, we calculate the average number of patients managed at each account seen here. Our best estimate is that on average, our priority one accounts manage about 230 patients each, our priority two accounts manage about 60 patients each, and priority three accounts about 40 each. This includes both those patients currently on treatment and those who are being monitored for progression and may need treatment in the future. Depth is especially important in our priority one and two accounts, who have already gained experience with OJEMDA. In these accounts, a substantial opportunity remains to accelerate adoption, drive increased use, and establish OJEMDA as the second-line standard of care. In priority three accounts, as we would expect, prescribers tend to be more cautious and wait to hear thought leader experiences before trying a new therapy. They also manage fewer patients, so they have less frequent treatment decisions. To get their first patient started, we continue to share the experiences of other physicians and our clinical trial data to help build their confidence in OJEMDA. While many accounts are already treating multiple patients with OJEMDA, the overall patient volume within these accounts reinforces our strong conviction that significant growth potential remains through deepening penetration and expanding usage across all of our accounts. To fully unlock OJEMDA's potential, our path forward is clear. First, as we just discussed, our greatest opportunity lies with our current prescribers and increasing the depth of their prescribing. Secondly, we must continue to expand our prescriber base by encouraging non-prescribers to try OJEMDA in their first relapsed or refractory pLGG patient. Across our customer base, we must continue reinforcing the value of OJEMDA in the second-line setting to drive deeper adoption and to firmly establish it as a new standard of care for these patients. We believe that our soon-to-be-released FIREFLY-1 two-year follow-up data will further aid in this effort. Finally, with an eye on the horizon, we want to ensure that physicians and patients are receiving the information and support that they need so that they can receive the optimal duration of treatment over time. This includes educating on managing adverse events, dose adjustments, and patient support. Through these areas of focus, we remain confident that we will continue to grow and increase the impact of OJEMDA. Now I'll turn it over to Charles for more details on our financial results.

Good afternoon, everyone. Earlier today, we reported detailed first quarter 2025 financial results in our earnings release. For today's call, I'll touch on a few highlights. In the first quarter, U.S. OJEMDA revenue was $30.5 million, which grew 11% compared to the fourth quarter, driven by a 16% increase in quarterly scripts. Our operating expenses, excluding cost of sales, were $68.9 million in the first quarter of 2025, which included $12.9 million in non-cash stock-based compensation expense. In comparison to our fourth quarter of 2024, when excluding the one-time charge of $20 million associated with the in-license of DAY301, we realized approximately 4% quarter-over-quarter decline in operating expenses. By maintaining a disciplined financial strategy as a cornerstone to building long-term durable growth, we anticipate that cost and operating expenses will remain relatively consistent the rest of the year with some quarter-to-quarter variability, which allows us to invest strategically in opportunities that support growth while prioritizing our clinical development plan. We remain well-positioned financially with a cash balance of $473 million and no debt at the end of the first quarter. As we continue to grow, our ability to balance disciplined financial management with measured investment is what sets us apart. Based on our current operating plans, we do not project Day One will require any additional financing in the future. As Jeremy mentioned earlier, our internal expertise in oncology development, registration, and commercialization is second to none. With the continued success of the OJEMDA launch and a disciplined investment approach, we are well-positioned to deliver long-term sustainable value. In closing, as we look ahead, our commitment remains the same: drive value for our shareholders; manage our resources responsibly; and above all, don't be afraid to disrupt the status quo of traditional drug development to give better targeted medicines to patients who urgently need new options. With that, I'll turn the call over to the operator for Q&A.

Thank you. We will now begin the question-and-answer session. Our first question comes from Anupam Rama with JPMorgan.

Hi, guys. This is Priyanka on for Anupam. Congrats on the progress for this quarter. Just one question from us. What are you seeing in terms of duration of therapy in the marketplace and how docs plan to use the drug long-term?

Priyanka, thanks for the question and the comments. I'll ask Lauren to comment on what we're seeing for duration to-date.

Yes. So we're approaching a year on the market. So it is early for us to comment on duration. What I will say is that we continue to see a very high percentage of patients continuing on therapy month after month. And the trends are similar to what we would expect considering the results we saw in the FIREFLY-1 study.

Thank you so much for taking my question.

Thanks, Priyanka.

Our next question is from Tara Bancroft with TD Cowen.

Hi. Good afternoon. So I was hoping if you could give us maybe a rough percentage of revenue that's accounted for from new patients versus ongoing patients. I know last quarter you said there were roughly about 280 active patients. So getting an idea of that updated number and the relative split would be really helpful. Thanks so much.

Thanks for the question, Tara. And what I can tell you is that the dynamics of our new patient starts and our patients on treatment are very similar to what we discussed in the quarterly call in February with respect to a couple of elements. The first is the rough percentage of on versus off-label remains at plus/minus around 10% off-label, 90% on label. With respect to the breakdown of patients we provided that year-end guidance in part because of the start we had with the EAP pool that converted post-approval on mass. Going forward our key metric really will be total scripts and of course revenues.

Thank you for your question. As a follow-up, can you provide any insights on the challenges you experienced in Q1, particularly related to gross to net and reimbursement?

So let me ask Lauren to first comment on seasonality, which she mentioned in the script, and then Charles can comment on gross to net.

Yes. Thank you for the question. So we did see some seasonality early in January due primarily to a delay in scans and physician appointments due to the year-end holiday. So we saw a slower ramp in January, but we have since seen new patient starts rebound. And as I mentioned, we had very strong NPS results in April. So that was the seasonality we did see. The normal seasonality you see in Q1 is related to payer dynamics and resetting the deductible. Of course, our patients are subject to that as well. However, the programs that we put in place did an effective job and really smoothed that transition for the large majority of patients. So we consider that a success. And with that I'll let Charles comment on gross to net.

Yes. So from a gross to net perspective, we've previously discussed the fact that we anticipate being in gross to net ranges of approximately 12% to 15%. For the first quarter, we'd remain in that range a touch closer towards the higher edge versus Q4 of last year mostly driven by a couple of realities of our business. The first being that we took a price increase in January of this year, which results in some CPI-U penalty associated with it. And then as Lauren just discussed, there was a modest amount of additional co-pay assistance required for patients as you would expect in the first quarter of the year. It did not drive it materially but it does impact our number modestly.

Okay. Great. I really appreciate the color. Thanks so much.

Thanks, Tara.

Our next question is from Alec Stranahan with Bank of America.

Hey, guys. Thanks for taking our question and congrats from us on the progress as well. I guess maybe just double-clicking on that prior question. How should we be thinking about new patient starts from here? Is April's trends sort of the run rate we should be thinking about for the rest of the year? And maybe, if you could talk a bit about inventory levels across the various distribution channels and any impacts there that maybe benefited the second half of last year and how we should be thinking about that going forward? Thanks.

Thanks, Alec for the question. I'll start on your new patient start topic and then ask Charles to comment further. So, what we've seen and expect to see going forward with respect to new patient starts is really what we've been emphasizing since launch, and that's a consistent and steady ramp of new patients starting over time as those patients either relapse or progress on other therapies and need a new therapy. And I would remind you and investors that this is not a typical oncology launch trajectory. We really think of this more as akin to a rare disease launch. And that's driven by the relative infrequency of treatment decisions, the longer durations of treatment, and the disease course for pLGG patients. All of that leads to, as we've said and we'll continue to see, a more gradual adoption and curve relative to adult oncology lapses, particularly those adult oncology launches that occur in a relapsed or a salvage setting.

And then as far as channel stock, how we've looked at it and discussed it previously remains consistent. From an operational basis and how we've expressed it to the Street, we keep our channel stock or attempt to keep our channel stock within a two to four-week of days on hand range. We do that in order as an internal target to make sure that we have adequate supply for the channel to meet patient demand, which of course is the main goal there. We remain in that two to four weeks there. So, we don't believe there is any really material effect to this current quarter from the channel stock changes itself, other than the consistent build you will get as you're increasing sales. So, we'll continue to see that as we see growth on a specific dollar basis, but we'll remain within that two to four weeks on hand as much as possible. If we step out of that range, we'll certainly discuss it with yourself and other analysts.

Makes sense. Thanks for the color.

Thanks, Alec.

Our next question is from Ami Fadia with Needham & Company.

Hi. This is Puna on for Ami. Thank you for taking our question. Could you talk about the penetration that you have within each of the priority centers? And what are you doing in order to, I guess, increase penetration in some of the lower accounts in each priority center? Thank you.

Really great question. Thanks for asking. I'll hand to Lauren, but I really want to reinforce the topic that you just brought up which is that sort of depth of prescribing multiple patients per center is really a key commercial goal for us of course. Lauren?

Yes. So, when we think of penetration of accounts we think of both breadth and depth, right? So first getting them to try it in one patient and then expanding to more patients. So, as we reported last quarter, in our priority one accounts, we have 100% of them who have tried OJEMDA post-approval. And priority two, we have three-quarters of them who have tried OJEMDA post-approval. And we've continued to grow that and even expand in priority three. But as Jeremy mentioned, now our focus is depth. So, once they have tried it, now it's about expanding their view of who is appropriate which patients are appropriate for OJEMDA. So, that means expanding their thinking on the location of the tumor or where they are in therapy and what they've experienced to date. So, that element of it. And then the second piece, which is even more important, is moving up in line. So many physicians try a new product in patients who have received all the other available therapies. So, they're a later line patient and moving—and as their confidence builds, they will start to use it earlier in therapy. And so that's really a focus for us is to drive confidence in OJEMDA and confidence in using it earlier in that second line. And with that, Jeremy?

Sure. Thanks Jeremy for the question. So yes, when you think about children with cancer and in particular a disease like low-grade glioma where children are expected to live well into adulthood, when you think about treatment options and in particular new treatments, of course you want a drug that works and reduces tumor size, but you're also weighing that against the potential for long-term effects and long-term toxicities. And obviously, when you have a new drug on the market and a new program, there's a lot of unknowns when it comes to the potential for any effects 10, 20-plus years down the line. So to Jeremy's point around the conservative nature of the physician community, it's one important factor that physicians will take into consideration when evaluating new treatments and how to weigh that against other options that are available.

Yes. And I think the key really is that giving those physicians deep experience with OJEMDA, we know is going to be essential for really getting them comfortable over time. And that's something that is occurring in the market. We're seeing it actively, especially among those investigators who are part of our FIREFLY-1 trial. And for the remainder that will continue. But that's critical to that depth point.

Thanks.

Thank you.

Our next question is from Soumit Roy with Jones Research.

Afternoon, everyone. Moving into the development pipeline, I would love to get us some details on the DAY301. What can you tell us about the—if possible the tumor type dose levels completed, what—when we should expect the data and how much details?

Soumit, thanks for the question. Let me kind of reiterate where we are and try to address those elements. So DAY301 is in dose escalation in the Phase 1 trial. The patients that we're enrolling in those dose cohorts are patients that have specific tumor types that are known to express at reasonably high levels, the target for that for the 301 program the ADC and that target is PTK7. So, it's endometrial patients, non-small cell lung cancer patients, triple-negative breast cancer patients. There's an array of all adult solid tumors at this point, who we're enrolling. And we have cleared the first dose cohort as we articulated in January. We are still in the dose escalation phase as we expected to be. We have not yet guided on the specific timing of when we'll have data from either dose escalation or potentially dose expansion cohorts available. But I can tell you that the plan is for us to get to those doses that we think are both safe and also in the efficacious range and begin to do two things. One is backfill patients into those dose cohorts so that we get more experience at those particular doses. And then two, once we have a body of data that's sufficient, move to dose expansion cohorts where we'll narrow to specific histologies. And we haven't really disclosed what those are until we have more clinical experience. We'll defer that disclosure in part for competitive reasons. But the dose expansion will be an important next step. And we anticipate that at that point, we'll be employing diagnostics such that we can prospectively define PTK7 expression for the patients who we put into those dose expansion cohorts.

Very helpful. Are you finding the literature around the PTK expression to be matching up with what you're seeing in the clinic? And curious any futility hurdle you have in mind in terms of safety or efficacy that will decide the go-forward and further disclosure of the data?

Also great questions. It's too early to say whether the publicly published data on PTK7 expression—and there are a couple of sources for that—are going to be consistent with what we see once we're really running trials with our own diagnostic. So I think it's just too early to say with any certainty whether that will be the case. I think in the second part of your question, can you just repeat it?

I'm trying to understand like what would be the go-forward decision-making point. Is it…

Yes, thank you. It's going to be a combination of safety and reasonable efficacy. And so what do I mean by that? We need to see in the Phase 1 trial a dose that we think we can move forward into a dose expansion phase and a Phase 2 that is tolerable and has a reasonably competitive profile with other programs that may be in development for the tumors of interest. And then we also need to see at least some evidence of anti-tumor activity. And the reason we need that anti-tumor activity is really just to have confidence that the exposures that we're seeing at the doses that we think are reasonable and tolerable may result in an efficacy signal that we could then pursue in registration programs.

Brilliant. Thank you, again.

Thanks, Soumit.

Our next question is from Andrea Newkirk with Goldman Sachs.

Good afternoon. Thanks for taking our questions. And congratulations on the acceptance of tovorafenib in Europe. And on that point, I was just curious if you could talk a little bit more about how you see the market in that geography compared to that of the US? And are there any differences in prescribing behavior? And how receptive is the community to ORR data versus outcomes endpoints like PFS or OS that probably aren't available until FIREFLY-2. Thanks so much.

Thanks, Andrea. Great questions. Let me comment broadly. First off, the overall market dynamic with respect to patient population in Europe, particularly is fairly similar to the US. There's no epidemiological distinction between the rates that you see in European countries versus the US. And so at a high level, you're talking about a similar patient population. And there are some differences, of course, in pricing and reimbursement by country. But we think the overall market shape looks quite similar. As far as standards of clinical care in Europe, they are broadly fairly similar to what you see in the U.S. with the exception that there's much less off-label use of products across the board in Europe. And so there's less MAP kinase or targeted therapy use in general in Europe. All of that being said to your question about response rate as a basis for assessing efficacy, that remains in practice how investigators and doctors who treat pLGG patients in Europe also think about what they're looking for in a product. And so it's broadly pretty similar to what you see in the US. Thanks, Andrea.

Our next question comes from Andres Maldonado with H.C. Wainwright.

Hi, guys. Thank you for taking my questions. And congrats on the progress. Two quick questions from us. So how should we be thinking about OJEMDA's positioning on the longer-term horizon? With respect to MEK inhibitors or other targeted therapies potentially being used in pLGG across the frontline and refractory setting? What are some of the concerns or dynamics there you can highlight for us? And second, with the cash position of $473 million, what's the appetite to bring in a new asset or in terms of business development? Obviously, we're looking forward to 301 and a couple of other pipeline programs. But any round color there would be great. Thank you.

Of course. Thanks for the question, Andres. So let me start with your question about the market dynamics and usage of targeted agents here in the US in pLGG patients. I'd say, broadly speaking, there's no clear standard of care in the second-line setting for BRAF fusion patients, who have pLGG. And that really underpins our goal of establishing OJEMDA as that second-line standard of care. And the most significant hurdle to getting there is really just entrenched use and behavior for existing therapies that are used off-label, whether those are chemotherapy or can be MEK inhibitors. There's small numbers of patients who receive other targeted therapies that are not in the MAP kinase pathway as well. And to a significant extent, what we're really looking to do is give physicians an experience that allows them to understand the product profile here as superior to their experiences with those other agents. And for all the reasons I've emphasized in the call earlier, that is going to take time. But we think there's a real opportunity, in particular, in that BRAF fusion population to establish that standard of care. Now, I think it's important also to note that in the V600 segment within pLGG, there are other approved agents, both in the frontline and in the relapsed setting in the MAP kinase pathway. And for that reason, our focus on the V600 segment is really more on sequencing after use of those agents because those are moving towards the frontline in that V600. And as another reminder, the rough split of patients is 75% to 80% of all pLGG patients are BRAF fusion patients. That's the area where there aren't any approved agents other than OJEMDA in the relapse setting, and then 15% to 20% of pLGG patients, who have RAF alterations are the V600s, where you do see dabrafenib and trametinib as approved agents. Sorry, one other—let me ask Charles to comment on business development as well. Thanks, Andres.

So from a business development perspective, consistent with what we've talked about previously, business development at Day One is critical to what we believe can generate long-term additional growth. We continue to have a very active business development process, look at a number of different opportunities, but also continue to keep a very high bar to what we want to invest in and what we want to put both our capital resources and our human capital to work at. So as we continue that evaluation, we'll look to find opportunities that we think can continue to grow the business. The timeline associated with that is often a challenge to pick the specific time. But when we do see things, we will move forward on them. An opportunity—one additional opportunity in our pipeline would be a great start for us, and it is something that we'll continue to evaluate over time.

Thank you, ladies and gentlemen, we have reached the end of the question-and-answer session and are out of time for today's call. Thank you for your time and participation. You may disconnect your lines at this time.