Good afternoon and welcome to the Curis Third Quarter 2021 Earnings Call. All participants will be in a listen-only mode. After the company's prepared remarks, call participants will have an opportunity to ask questions. Please also note this event is being recorded. I would now like to turn the conference call over to Curis’ Vice-President of Investor Relations and Corporate Communications, Elif McDonald. Please go ahead.

Thank you, Garry. Welcome to Curis' third quarter 2021 earnings call. Before we begin, I would encourage everyone to go to the Investors section of our website at www.curis.com to find our third quarter 2021 earnings release and related financial tables. I would also like to remind everyone that during the call, management will be making forward-looking statements, which are based on our current expectations and beliefs. These statements are subject to certain risks and uncertainties, and actual results may differ materially. For additional details, please see our SEC filings. Joining me on today's call are Jim Dentzer, President and Chief Executive Officer; Bill Steinkrauss, Chief Financial Officer; and Bob Martell, Head of Research & Development. We will also be available for a question-and-answer period at the end of the call. I'd now like to turn the call over to Jim. Jim?

Thank you, Elif. Good afternoon, everyone. It’s my pleasure to welcome you to Curis’ this third quarter earnings call. As we look back on the year, we have come so far as a company, making important progress with both of our lead clinical programs, CA-4948 and CI-8993. Every day at Curis, we strive to develop the next-generation of transformative cancer therapies that meaningfully improve and extend patients' lives. In the third quarter, we made significant progress toward that goal. To start, let me review our lead asset, our novel small molecule IRAK4 inhibitor CA-4948. CA-4948 is the most advanced IRAK4 inhibitor in clinical development for cancer and is currently being evaluated in nine distinct patient populations across AML, MDS, and B cell cancers. There is a critical unmet need for safe, fast-acting treatments for patients with AML, the leading cause of leukemia deaths in the United States. In MDS, the need may be even more critical, as so many patients are left with only supportive care as their best option for treatment. We are excited that the original scientific rationale for CA-4948 and IRAK4 inhibition has been followed by consistent and encouraging results in the lab and, so far, consistent and encouraging results in the clinic. In both our B cell cancer and AML and MDS studies, CA-4948 has continually demonstrated a well-tolerated safety profile and the ability to demonstrate improved efficacy over multiple cycles of treatment. These findings were most recently presented at the EHA meeting in June, where we shared data from the monotherapy arm of our Phase 1/2 AML/MDS study demonstrating clear efficacy with no dose-limiting myelosuppression, a potentially key differentiating factor that may allow even extremely sick patients with low thresholds for drug tolerability to be treated with CA-4948. Our second lead program is for our first-in-class monoclonal anti-VISTA antibodies CI-8993, a novel immune checkpoint inhibitor that we are developing in collaboration with ImmuNext. CI-8993 is a clinical-stage human IgG1 kappa monoclonal antibody designed to antagonize the VISTA signaling pathway by increasing T-cell mediated immunity and reducing myeloid-derived suppressor cell or MDSC activity. VISTA is a key checkpoint for holding T cells in a quiescent state, preventing their transition into effector cells facilitated by CTLA4 and PD1 therapies. In addition, VISTA is a key driver of MDSCs. These are two fundamental and unique roles of VISTA that are not captured by existing immune mediating therapies. VISTA expression is also believed to be a key resistance mechanism to PD1 and CTLA4 therapies, as VISTA expression is dramatically elevated as patients become resistant to those treatments. Finally, VISTA is highly expressed directly on certain tumor cells themselves, in addition to the surrounding immune cells, including mesothelioma and subsets of breast, lung, and gynecologic malignancies. Treatment with anti-VISTA antibodies has been shown to suppress the growth of both transplantable and inducible melanoma in preclinical models. CI-8993 is currently being evaluated in a Phase 1 dose escalation study for the treatment of relapsed or refractory solid tumors. With that, let's dig into some detail on our ongoing programs, starting with the IRAK4 study in leukemia. As I mentioned, we were pleased to present at EHA earlier this summer, our positive updated data from the monotherapy arm of our AML/MDS study, which expanded upon previously observed findings of single agent efficacy across the spectrum of late-line AML and MDS patients despite these patients having already experienced several unsuccessful prior lines of therapy. We also demonstrated that near-total IRAK4 inhibition was achievable at every therapeutic study dose. With these data, we saw that 300 milligrams BID struck the optimal balance of durable anticancer activity and extended tolerability. Accordingly, we selected it as the recommended Phase 2 dose going forward. This was in line with the findings from our earlier monotherapy study of CA-4948 in NHL, where we also selected 300 milligrams BID as the primary study dose for further evaluation. We continue to be pleased with the pace of enrollment in our monotherapy study of CA-4948 in patients with a U2AF1 and SF3B1 spliceosome mutation. As we have noted previously, our goal is to have 10 to 20 patients with a spliceosome mutation on study by the end of this year. We believe data from these patients may pave the way for discussions with the FDA on the registrational path forward in the first half of 2022. We expect to hit that 10 to 20 patient goal and plan to provide a high-level update of safety and efficacy data from a subset of these patients in January. While we obviously don't have data for all 10 to 20 patients just yet, we do expect in January to have initial efficacy data for eight to 10 spliceosome patients and three FLT-3 patients, or nearly three times the data we presented at EHA just five months ago. This update will include all patients enrolled by mid-September, allowing time for at least two disease assessments to determine marrow response. Not all patients achieve responses this quickly, but we believe this two assessment view will provide a nice interim snapshot of the clear progress we are achieving in this study. For these patients, we hope to see consistency with the data we shared at EHA, meaning we hope to see clear anticancer activity and reduction of tumor burden across the population. A majority of patients should see their blast counts drop all the way down into the normal range, achieving an objective response and highlighting CA-4948's compelling ability to fight cancer as a monotherapy. Further, we would hope to see additional evidence of hematologic improvement, perhaps even a second patient with complete response to determine whether some patients may be capable of achieving a CR despite the effects of damaged marrow from both their disease burden and from their prior treatment. Additionally, we would like to see that the finding of rhabdomyolysis previously seen at higher doses does not limit treatment at the recommended Phase 2 dose of 300 milligrams BID. This will provide an early look at the data. We expect to have a more comprehensive data update with the full 10 to 20 patients at a medical conference next year. On the heels of our promising monotherapy data, we were very excited to announce the recent initiation of our Phase 1/2 combination therapy trial of CA-4948 in AML and MDS with the positive preclinical data in combination therapy that we presented at EHA, demonstrating CA-4948's synergistic anti-tumor activity when used in combination with azacitidine or venetoclax. We are optimistic this combination study will allow us to advance CA-4948 as a new treatment for patients with AML and MDS across the broader AML and MDS patient population, where there remains a great unmet need, with many patients ineligible for intensive chemotherapy. The combination portion of this study includes two arms, CA-4948 plus azacitidine for patients naive to HMA and CA-4948 plus venetoclax for patients naive to venetoclax. The primary goal of this combination study is to determine the recommended Phase 2 dose for CA-4948 in combination with azacitidine and in combination with venetoclax, based on safety, tolerability, and biological activity, including pharmacokinetic and pharmacodynamic findings from the study population. We expect to have initial data from this combination study in 2022. I would like to briefly touch on the ongoing Phase 2 LUCAS IST for patients with lower risk MDS, being led by the Co-Chairman of EHA's Scientific Working Group on MDS, Dr. Uwe Platzbecker. We realize there's a lot of interest in this study because success in this study could lead to a potential breakthrough in the MDS field. So even though we have a longer time horizon for this study, and it is not a company-controlled study, we hope to provide an update on the progress of the LUCAS IST in 2022. The current standard of care in low-risk MDS is supportive care, such as EPO stimulating agents, which can be effective for patients with low serum EPO or treatment options that enhance the production of red blood cells. Unfortunately, these interventions do not alter the underlying disease. Their effect is often transient, and they do not prevent progression to AML or further disease complication. In contrast, CA-4948 is disease-modifying, targeting a key driver of the underlying disease. Given the direct, non-myelosuppressive targeting of IRAK4 and its demonstrated safety profile, we believe CA-4948 could potentially offer a safe and transformative disease-modifying alternative for patients in this earlier stage of disease. In conclusion for AML and MDS, our success earlier this year led us to expand our clinical investment to include both monotherapy and combination therapy and to include patients across the spectrum of disease from low-risk MDS to high-risk MDS to AML. We look forward to providing data updates on all of these studies in 2022. Moving to our B cell cancer program, we have made steady progress with our CA-4948 clinical development in B cell cancers. Data from our monotherapy Phase 1/2 study highlighted a clear reduction in tumor burden and a strong durability profile, which is particularly notable with a novel monotherapy agent in such extremely sick patients. Based on these findings, as well as our preclinical work, we believe CA-4948 is the ideal candidate to combine with BTK inhibitors to maximize the down regulation of NF-kappaB. Earlier this year, we initiated the combination study evaluating CA-4948 and ibrutinib, which is expected to enroll approximately 18 patients in a three-plus-three design, starting at 200 and escalating to 300 milligrams BID. Ibrutinib dosing will be determined based on the appropriate dose for the patient's type of cancer. We are pleased to share today that CA-4948 administered at the 200 milligram twice daily dose has been well tolerated in combination with ibrutinib, with no dose-limiting toxicities observed. We are currently evaluating the 300 milligram twice daily dose of CA-4948 in combination with ibrutinib. The trial is progressing well, and we expect to report initial data from this study at a medical meeting in 2022. While we are obviously excited about our ongoing studies in AML, MDS, and B cell cancers, we are equally excited by the breadth of its potential application in other cancers and are working with our collaborators at NCI and in the broader KOL community to evaluate additional opportunities for CA-4948. In October, we announced at the triple meeting conference on molecular targets in cancer therapeutics, new preclinical data highlighting the potential benefit of CA-4948 in multiple new applications. These data demonstrated that CA-4948 can cross the blood-brain barrier and enhance survival in patients with primary central nervous system lymphoma, an incredibly aggressive and rare form of lymphoma in which malignant cells form in the lymph tissue of the brain and spinal cord. Additional data at the meeting highlighted CA-4948 as synergistic with small molecules targeting BCR signaling, including both idelalisib and ibrutinib, suggesting it may help overcome secondary resistance to these therapies in marginal zone lymphoma. Last but not least, turning to CI-8993, our first-in-class monoclonal antibody targeting VISTA for patients with relapsed or refractory solid tumors. Enrollment remains on track in this Phase 1 study, and we expect to report initial safety data in our January 2022 update. This is highly differentiated from other existing checkpoint inhibitors because of its primary role in enforcing T-cell quiescence. When unblocked, VISTA can sequester a large proportion of T-cells in a quiescent state, preventing them from being acted upon by anti-CTLA/4 or anti-PD/1 antibodies. VISTA is also a primary driver of MDSCs, which independently promote T-cell exhaustion and suppress pro-inflammatory tumor-associated macrophages. This year, our primary objective is to evaluate safety and tolerability and confirm that using our revised protocol, the on-target side effects of CI-8993 can be safely managed, enabling dose escalation up to and beyond all doses studied with this anti-VISTA therapy in prior clinical studies. Achieving this critical milestone, which we hope to report on in January, will enable us to begin the exploration for efficacy at higher dose levels in 2022. I would also note that earlier today, we announced that a preclinical data submission for CI-8993 was accepted for a poster presentation at the annual meeting of the Society for Immunotherapy of Cancer, SITC, being held from November 12 to the 14th. We look forward to sharing additional data from this program at that time. In summary, this has been an incredibly exciting year for Curis, and we have even more to look forward to. Specifically, we expect to report in January both initial safety data from our anti-VISTA program, the Phase 1 monotherapy study of CI-8993, and an update on safety and efficacy data from our Phase 1/2 monotherapy study of CA-4948 in AML/MDS patients with certain spliceosome or FLT-3 mutations. This update will be followed by a more comprehensive update later in 2022. Also in 2022, we plan to report initial data at a medical meeting from the ongoing Phase 1/2 combination study of CA-4948 plus ibrutinib in patients with B cell cancers. Before turning the call over to Bill to discuss our financials, I always like to extend my gratitude and appreciation to the entire Curis team for their dedication and hard work. We are eager to build upon our efforts and advance our next-generation targeted cancer programs to help patients in need. With that, I'll turn the call over to Bill to review our financial results for the quarter. Bill?

Thank you, Jim. For the third quarter 2021, we reported a net loss of $11.1 million or $0.12 per share on both the basic and diluted basis, as compared to a net loss of $6 million or $0.11 per share on both the basic and diluted basis for the same period in 2020. For the nine months ended September 30, 2021, we reported a net loss of $31.8 million or $0.35 per share, as compared to a net loss of $22.4 million or $0.52 per share for the same period in 2020. Revenues for the third quarter 2021 and 2020 were $3 million and $2.7 million, respectively. Revenues for the nine months ended September 30, 2021 were $7.5 million, as compared to $7.8 million for the same period in 2020. Revenues for both periods comprised primarily of royalty revenues recorded on Genentech and Roche’s net sales of Erivedge. Operating expenses for the third quarter of 2021 were $13.1 million as compared to $7.5 million for the same period in 2020. Operating expenses for the nine months ended September 30, 2021 were $37 million as compared to $26.4 million for the same period in 2020. They were comprised of the following: cost of royalty revenues, primarily announced due to third-party University patent license orders in connection with Genentech and Roche's Erivedge net sales, were $0.2 million for the third quarter of 2021 as compared to $2.1 million for the same period in 2020. Cost of royalty revenues were $0.4 million for both the nine months ended September 30, 2021 and 2020. Research and development expenses were $8.6 million for the third quarter of 2021 as compared to $4.7 million for the same period in 2020. The increase in direct research and development expenses for the quarter is primarily attributable to increased clinical and manufacturing costs for our clinical programs. Additionally, employee-related R&D costs increased by $2.3 million, primarily attributable to increased stock-based compensation and personnel costs as a result of additional headcount. Research and development expenses were $24.1 million for the nine months ended September 30, 2021 as compared to $17.5 million for the same period in 2020. General and administrative expenses were $4.3 million for the third quarter of 2021 as compared to $2.6 million for the same period in 2020. The increase in general administrative expense was driven primarily by higher costs for stock-based compensation, personnel, professional and consulting services. General and administrative expenses were $12.5 million for the nine months ended September 30, 2021 as compared to $8.6 million for the same period in 2020. For the third quarter of 2021 and 2020, net other expense was $1 million and $1.3 million, respectively. Net other expense primarily consisted of imputed interest expense related to future royalty payments. Net other expense was $2.3 million for the nine months ended September 30, 2021, as compared to $3.8 million for the same period in 2020. As of September 30, 2021, Curis's cash, cash equivalents, and investments totaled $149.8 million, and there were approximately 91.6 million shares of common stock outstanding. We expect that our existing cash, cash equivalents, and investments should enable us to maintain our planned operations into 2024. With that, I'd like to open the call for questions. Operator?

Ladies and gentlemen, at this time we'll begin the question-and-answer session. Our first question is from Alethia Young with Cantor. Please go ahead.

Hey, guys, thanks for taking my questions. Just a couple. One, I wanted to start with, maybe the kind of, I don't know if you're ready to kind of give this granularity. But should we be thinking that kind of the FDA conversation probably would happen after kind of the second more robust update? So maybe perhaps like a little bit later in the first half of 2021. I guess my this kind of leads into my second question, which is, I guess with 10 to 20 people like do you think that's going to be sufficient? Do you have safety and other stuff from other studies? But just do you think that's what's your confidence, everyone that being that kind of enough to trigger a conversation that can inform potential pivotal strategy even though I know it's a much smaller population? And then my third question was, you mentioned, I guess you mentioned the complete response, which existed, but then you mentioned potential for another complete response. So I just wanted to confirm that that's not been seen yet. It's just what you hope to see? Thanks.

Yes, thankfully, this is Jim. So let me start with that last one because I know that's of high interest. It's what we're hoping to see this; obviously, it's not a call where we're discussing the data that we have seen. We've got a couple of months for the data to mature. But when we think about what we're hoping to see with this drug, this drug has shown a really unique ability as a monotherapy to reduce cancer burden across the spectrum. With a majority of these patients getting their blast counts all the way back down to the normal range. That's what we want to see. We've already seen one complete response; we'd love to see another one. We want to give that update in January. We don't have all those data yet, but of course, if you ask for what we were hoping for, that was sort of our guidance. In terms of the FDA meeting, we have always planned and we've been very clear about this all year. We have always been planning to get the concentration focus on spliceosome patients and FLT-3 patients. When we saw that the data we had at EHA was so compelling, we really ramped up our efforts to get patients on drug. Our regulatory consultants had given us guidance that in order to meet with the FDA, we probably need 10 to 20 patients. And that's our goal is to get 20 patients, 10 to 20 patients on drug by December 31. Whether or not the FDA agrees with those consultants and takes our meeting and has the discussion we hoped for, of course, we don't have any control over. But the general consensus seems to be that if we can get 10 to 20 patients and the data look consistent, then we should have a good shot at having a successful discussion with the FDA. The reason for the new update that we're offering in January is, of course, we're very pleased with what we said. We don't have all the data yet, but the data that we have, we think do look compelling and consistent with what we've been. And we think that if we can make that cut-off to have 8 to 10 patients at year-end and with spliceosome mutations, and another three with FLT-3, that does go a long way to giving everybody our investigators, the KOL community, and investors a very good sense of where the data is trending. We've only seen three patients so far. Where are the data trending so that we have a good sense of how that discussion with the FDA might go? That's the point of that update. So we're very happy with where we sit, but of course we've got more data internally and we'd like to make it public so that January plan is to make all of that public.

And then just maybe it's the follow on and the safety with the ibrutinib combination that you mentioned, you haven't seen anything like related to rhabdo or anything, so I think you said there was no deal to you? So I just want to confirm that.

Yes, actually, Bob, would you mind talking about that?

Yes. So we've obviously continued to dose patients with our 300 dose level in the monotherapy study that's going along well. As Jim said, we'll update the safety on that. We probably won't be giving an update on the combination study at that point. But yes, there were no dose limiting issues at that initial dose level, so it was quite well tolerated, which is really exciting. Because, as you know, now we're able to dose escalate up to the full dose of both drugs.

Great, thank you.

The next question is from Dane Leone with Raymond James. Please go ahead.

Hi, thank you for taking the questions and congratulations on the progress. I guess, in light of the announcement that you're going to host an update call in January. Now, maybe, given this isn't going to be the full dataset of what you hope to have in spliceosome and FLT-3, could you maybe just clarify how to set expectations? I guess the worry is, if you're giving this update in January, everyone tries to interpret it in terms of a dataset that you'd actually walk into the FDA with, maybe something akin to the men and inhibitor class. But it seems like from your commentary, you're trying to give more of an anecdotal update. So maybe you can just provide some caveats to what this data analysis is actually going to look like and the context that you're trying to hope to pull out of updating people publicly, without maybe the full datasets here for the spliceosome group.

Sure, we’re not making an initial comment on that now let's start to expand as well. So I think the thought process is, of course, we gave a terrific update of three patients, but it was only three patients at EHA with a spliceosome mutation. In fact, one FLT-3 patient did exactly what we hoped, exactly what the literature would suggest, that patients that did not respond to other FLT-3 inhibitors coming onto our study. And within two cycles, not only getting a response, but seeing complete eradication and mutation. I mean, both datasets, the first three and the one look terrific. And we then moved fast and furious to have a discussion with the FDA. I think what we're just trying to respond to is it's a long time between EHA, in that discussion with the FDA, we have a lot of confidence. And we are seeing terrific progress in that study. We wanted to give everybody else a chance to see what we're seeing. So it's not the full update that we'll have in six months from now. But we think the data that we have now and the data we're going to have by year-end is a nice update, and it gives us a significant upgrade. Just five months after EHA, we're going to triple the dataset. We think that's going to be I think a very robust discussion. It's not anecdotal. And it's not the complete total of all patients that will ever be on the drug. But it's a significant increase of the data size, and really should give everyone a chance to share our enthusiasm for the progress of the study. Bob, would you like to add to that?

I think you described it well, Jim. So basically, as we've said, we've been so excited about the disease-modifying aspect of this drug, really, especially in this population seems to have a really potent effect on limiting blast growth and reducing blast. We think this is a therapy that the FDA will be very interested in, in a population where no other drugs are approved. Based on our EHA data, we sought to really build our case around that and focus on the FDA, with our goal being we would like to update the community publicly along the way with data when we have relevant updates. And so that's the goal here in January. This isn't going to be the exact datasets that we take to the FDA, but it will be, as Jim said, a tripling of the number of patients that we've presented publicly so far, and we think it should give the community a lot more confidence about the drug and the anti-cancer activity of the drug going into that hopeful potential discussion with the FDA.

Great, sorry, just clarify one thing. What at what point of follow up for the cohort of spliceosome mutations? Are you going to go to the FDA? Are you looking to have that fully enrolled with clinical follow up for all those patients to properly evaluate efficacy before having that discussion with FDA? Are you doing that before you have a more mature dataset in that cohort?

Well, there obviously, when we do go, there will be a range of patients in terms of duration on study. We'd obviously like to have a minimum duration for all the patients that we present to them. It's an ongoing process. Even the data that we present to them will be interim data to some extent, but we think by the first half, we've committed to considering that as a possibility in the first half of 2022, and we believe that we'll have enough data that's mature enough at that point to speak with them or at least we'll request to speak with them.

Okay. So just to be clear, you won't actually have feedback from the FDA when you give the update in January, correct?

That's right.

Yeah, yeah, no, no we should be really clear, Dane. We haven't already spoken to the FDA; that plan has not been right. We are planning a meeting with the FDA in the first half of 2022. This is just a chance to give everybody a snapshot to see all of the data that we are now seeing, tripling the size of the data they've seen so far, to give them a greater confidence that we really do have something. The skepticism that you get into developing a new drug in this space should be high. In monotherapy, there is nothing approved for these patients because nothing works; the data that we've seen so far is remarkable, but it's small, NF-3, and NF-1. I think providing people a greater sense of competence, that this really is something that nobody has seen before, that we really do have a drug in monotherapy that can address cancer in these patients I think is tremendously exciting. And so we're very interested in providing that update.

Okay, thank you.

The next question is from Justin Walsh with B. Riley Securities. Please go ahead.

Hi, thanks for taking the question. Maybe you give us some color on what we should be looking for in the B-cell cancer combo data. I believe that you have a Simon 2-stage design to help explore signals and the expansion portion. But maybe you could remind us what response rates do you think would be meaningful and the various lymphoma indications you're looking at?

Yes, it's better to ask Bob. Bob?

Yes, so obviously started that. That's a combination with ibrutinib, and just to recount, ibrutinib hits the other primary pathway that activates NF-kappaB, and other BTK inhibitors inhibit that pathway. The 4948 is really the only drug that's targeting the other primary pathway activating NF-kappaB in these malignancies. And it's TLR signaling through the myddosome, and that drives the combination that we're putting in here. Right now, clinically, we've seen activity with our drug as a monotherapy targeting this pathway. Obviously, ibrutinib and other BTKs have monotherapy activity there. What we would like to do is enhance that activity as part of this combination. The study you mentioned really has four different cohorts, each of which is what we consider a low-hanging fruit for targeting IRAK4. These are indications where there's a high incidence of MYD88 mutation, a key part of the myddosome and strong signaling through NF-kappaB via that pathway. It's also indications where we think there's a straightforward registrational path as well. Each of them, we will be looking to gain estimates of the efficacy of these combinations. As one example, the fourth cohort is one where we're looking at adaptive resistance. That's where a patient has experienced progression on ibrutinib. In this case, we add 4948s, and so to address your question, any efficacy that we see there suggests proof-of-concept of adding 4948 to ibrutinib as part of that combination. Ultimately, once we get those estimates of efficacy, we'll discuss with the FDA what we think is a relative relevant target or a pivotal study going forward from that. But we haven't put a stake in the ground specifically for a target response rate. We would obviously hope to get a reasonable percentage of patients having durable responses and hopefully deep responses, and in many cases deeper than what we would expect with the BTK inhibitor alone.

Do you have an idea of how many patients we can expect in that readout, and whether those include patients from the four specific cohorts of interest?

Yes, so just to reiterate the four cohorts. I already mentioned one, which is the adaptive resistance, and that can be any patient across any indication who's had a root node. The other three include primary CNS lymphoma, which is a very deadly and difficult to treat disease that actually has a very high incidence of mid-88 mutation. Myddosome lymphoma is another one that has a high activation of NF-kappaB through this pathway. And so with those, we hope that we'll see strong efficacy there.

The next question is from Soumit Roy with Jones Trading. Please go ahead.

Hello, everyone. Thanks for taking the question. If you could rewind us a little bit on the natural history of progression of MDS from low risk to high risk, do we see an increase stimulation of these spliceosome mutations? And what would the standard of care response rates look like? Some kind of benchmark to look at?

Yes, hi, Soumit. Thanks for your call. Bob, would you mind commenting on that? I know this is more your area of expertise.

Yes, so the natural history, it's interesting, these spliceosome mutations occur extremely early in the natural history of the disease. As you may know, they've been known for quite a while and correlate oftentimes with one of the first mutations found in a disease. It wasn't until about a year and a half or two years ago that it was even known what the spliceosome mutation did in terms of their oncogenic role. It was some work by Amit Verma and Dan Starczynowski, who determined that it's actually this alternate splicing of IRAK4-L. As I mentioned, it's what's called a founder mutation. These spliceosome mutations tend to persist throughout the disease. Normally, a patient may start out with low-risk MDS with one of these spliceosome mutations, and over time, their disease starts to accumulate other changes and ultimately becomes more aggressive. Unfortunately, some patients die along the way because of the complications of the disease such as neutropenia and low platelet counts, thrombocytopenia. But in general, these spliceosome mutations persist if the patient does evolve their disease and ultimately can transform into leukemia AML. And again, during that transformation, most of the patients still retain that IRAK or the spliceosome mutation, suggesting this is a critical component that's important for the survival of the disease itself. That's why we think this drug has a very important role for all stages and exactly why we're going after the low-risk disease as part of the Uwe Platzbecker collaboration, as well as these later lines, with the high-risk MDS and ultimately the AML. The response rates and information that you look for in terms of endpoints across the spectrum from low-risk to high-risk MDS, all the way to AML differs depending on the specific disease setting that you're looking at. For example, in low-risk MDS, an appropriate endpoint might be transfusions, the number of transfusions required or frequency or even achieving transfusion independence. As you get to higher risk disease, you're looking for disease control, reduction in blast codes, as well as reduction in transfusions and hematologic improvement. Same with AML; you're looking for a variety of different endpoints. When we think about this population that we're examining with spliceosome, it's important to remember the very potent inflammatory microenvironment that develops because of these spliceosome mutations and IRAK4-L. That creates a damaging effect on the marrow, including healthy marrow. I often liken it to hepatitis, where in hepatitis C, it causes liver cirrhosis, and you can even get rid of the hepatitis C, but the cirrhosis of the liver remains; this can be the case in the bone marrow. Healthy marrow may be damaged; it makes it difficult in these spliceosome mutations to recover. That's important to think about when we're contemplating potential efficacy hurdles. There was a nice publication a few years ago that looked at intensive induction chemotherapy in AML. In fact, in the broader population, 80% of patients achieve full hematologic recovery. However, when you break out those patients with spliceosome mutations, only about 22%, almost three or fourfold less, of the patients are able to achieve a full CR, and if they had an SF3B1 mutation, that's a spliceosome mutation, so dramatically reduced ability to achieve hematologic recovery in this population. That's what we want to think about when we consider precedents for response rates; it's important to take that into consideration. But that'll be a really big goal of ours when we share it with the FDA; we've seen striking anticancer efficacy with this drug so far. We've also seen good strong evidence of potential endpoints. We will synthesize all of those data and the additional patients that we will now be able to take to the FDA, which I think will help us in that discussion with them, ultimately to come to an agreement in a population, for example, a spliceosome mutation, where the endpoints that we need to shoot for, are likely to be different than what you might see in typical de novo AML, for example. Does that answer your question? Kind of longer than...

Yes. Thank you all for the really detailed color; really, a lot to look forward to in January and beyond. Last question is, can you remind us if you're switching mutant patients, can they be FLT-3 inhibitor experienced or do they have to be naïve?

They can be FLT-3 inhibitor experienced. In fact, the patient we actually presented at EHA was FLT-3 inhibitor experienced. That patient had been treated with ibrutinib and had absolutely no response to ibrutinib, which is one of the primary FLT-3 inhibitors that are approved by the FDA. They came on to this study and had a dramatic reduction in the bone marrow and blast, achieving a PR and doing quite well. So, I think the important point to note here is that for patients who are on FLT-3 inhibitors, it's been demonstrated that one of the primary mechanisms of resistance to those inhibitors is in fact, signaling through TLR pathways and specifically through IRAK4. So, the literature suggests combining an IRAK4 inhibitor with a FLT-3 inhibitor. Fortunately, 4948 is the perfect drug in this case because we hit both IRAK4 and FLT-3. So, yes, we'll definitely be open to both of those possibilities.

Got it. So you will continue to enroll FLT-3 experienced? Okay, thank you so much for taking the questions and congrats on the progress.

Thank you very much.

This concludes our question and answer session. I would like to turn the conference back over to the Company's President and Chief Executive Officer James Dentzer for any closing remarks.

Thank you, Gary. And thank you everyone for participating in today's call. As always, thank you to the patients and families participating in our clinical trials, to our team at Curis for their hard work and commitment, and to our partners at Aurigene, ImmuNext, and the NCI for their ongoing help and support. We look forward to updating you again soon. Operator?

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