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Citi 18th Annual BioPharma Conference

Sep 6, 2023

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Well, good morning, everybody. My name is Andrew Pucher. I'm a managing director in Citi's Life Sciences Investment Banking Group, and I have the pleasure of being joined on stage here by Bill Newell, who's the CEO of Sutro Biopharma. Maybe, Bill, I could just give a quick intro, and then we could get straight into it. Bill's a seasoned life sciences executive and an active industry supporter and participant at Sutro. He served as the CEO and a member of the board since 2009, and previously was President of Aerovance, the CBO at QLT and part of the executive team at Axys Pharma. Bill, thank you very much for joining us here today. First one in the morning. Maybe just to start with a little bit of background, Sutro, I think, is quite a unique clinical stage biotech.

You've got two parts to the story here. Part one is a proven ADC platform that has delivered six clinical trial candidates to date, including two high-value, wholly owned assets that we'll talk about today. You also have a manufacturing platform that has enabled you to partner with large pharma and provide the technology to stand up what we know today as Vaxcyte, formerly SutroVax. Maybe to give some context to the audience, could you start with just a short background on the company for the uninitiated and how you've gotten to where you've gotten with the assets that you have today?

Bill Newell
CEO, Sutro Biopharma

Great. Thanks, Andrew. It's a pleasure to be here and really enjoy the opportunity to tell the Sutro story today. When I started in 2009, Sutro was a nascent platform company using a novel approach to making large molecules. We use a cell-free protein synthesis technology. The interesting thing about the cell-free protein synthesis technology is that it can make complex molecules just as well as CHO or E. coli systems do, but we make them rapidly, much faster. So we can make at usable quantities antibodies for antibody drug conjugates in less than 24 hours. And that allows for rapid prototyping of different molecules to identify the best using structure-activity relationship principles.

It also allows us to scale up quickly so that we can do a lot of things that people have to wait months, if not years, in order to validate that the molecule that they have, has an appropriate safety profile to move forward into the clinic. That technology required us to develop a manufacturing capability, which you alluded to, because Sutro is the only company in the world that makes molecules using cell-free protein synthesis at a scale that allows us to have clinical supplies and ultimately will allow us to have commercial supplies.

Along the way, we decided to employ that technology in the field predominantly of antibody-drug conjugates, and more recently, we've tried to extend the technology to do immunostimulatory ADCs in our collaboration with Astellas, that we may touch on later, as well as a new concept that we call ADC2, which would have two different killing modalities on the same molecule. Now, for us, it was important always to be able to say that we had our own programs, and we will talk about them today. You know, we've got two in the clinic, STRO-001, which is a CD74 antibody-drug conjugate, being developed in China right now by our partner, BioNova, and STRO-002, which is our flagship molecule.

We initiated a pivotal trial in platinum-resistant ovarian cancer that we're very excited to be at that stage of development, and we have a few other opportunities to expand the label for that molecule beyond ovarian cancer, and we'll talk about that as well today. We have a next-generation ROR1 ADC, which we call our STRO-003 program, and then we have STRO-004, which is a tissue factor ADC. Both STRO-003 and STRO-004 are targeted for entry into the clinic within the next 12-18 months. So we've got a robust platform technology. We've been fortunate to be able to partner with companies like Merck, where we've worked with them on an IL-2 derivative that is presently in the clinic both as a single agent and in combination with Keytruda. I know the cytokine space has been challenging for some.

We've got a novel approach that we jointly developed in collaboration with Merck, and so we're looking forward to seeing the results from their early clinical development in the future. And as you mentioned, our technology underpins a company called Vaxcyte, which is using our technology to make a 24-valent pneumococcal conjugate vaccine. It's a very exciting opportunity for them, and we've been able to leverage our relationship with Vaxcyte in ways to provide capital, so that we don't need to access the public capital markets to the same extent that perhaps other biotechs do.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. Thanks for the overview. So there's certainly a lot going on. Why don't we focus on, as you put it, your flagship molecule and program, STRO-002, luvelta, which is your Folate Receptor α-targeting ADC for ovarian and endometrial cancers. Could we start, Bill, maybe take us through... There's obviously been a lot of attention around this with ImmunoGen's MIRASOL data and Elahere approval. Tell us where you're at in the clinical development of luvelta and how investors should think about luvelta's market opportunity versus ImmunoGen's.

Bill Newell
CEO, Sutro Biopharma

Great. Let me start with a little background on why we initiated the program and why we think our molecule has a differentiated profile that is actually gonna give us a broader opportunity from a commercial standpoint than the opportunity that ImmunoGen has. Which, by the way, we're excited that they have now demonstrated something that we believe for a long time, and that is folate receptor-α is a validated target for women with advanced stage ovarian cancer. So I think the question about the target's validity has been put to rest by them, and we are on the path to be the second to market with our molecule. We have started a pivotal trial. I'll talk about that in a minute, but let me talk about why we entered into this program originally.

When the platform technology was being developed, what we wanted to understand was, is it applicable in the solid tumor space, or in the hematologic malignancy space, or both? In the early days, more success was found for ADCs in the heme space, but over time, as technologies have developed and improved, there have been great successes in the solid tumor space. And so we needed to understand that. We looked around and thought that the ovarian cancer patient population was one of high unmet need, particularly as you get to the later stages of ovarian cancer. We saw that ImmunoGen had developed a molecule, which is now called Elahere, for which there is an accelerated approval at present in the United States. We saw that that was a molecule that had what we thought was a very narrow therapeutic window.

They have to dose at one level, 6 mg/kg. If they dose higher, they get such toxicity that it is not well tolerated by patients. If they dose lower, they lose a lot of their efficacy potential. And they also have to focus on women who have the highest expression folate receptor-α. probably about 30% of women have that high level of expression folate receptor-α, and the other 70% have not been shown to have benefit as single agent activity through clinical development. And so we thought, well, it's a good target. They've started to demonstrate that. I think that's now, without a doubt, the case. But the molecule is not as optimized as it could be. And part of the reason is it's a heterogeneous mixture. It is not a single species in the vial.

It is a multitude of species, which means some are optimal for treating the patient, and some are suboptimal for treating the patient. We thought that if we could develop a homogeneous molecule with a potent warhead, we have a drug-antibody ratio of four, precisely. Their drug-antibody ratio is an average of four, meaning some species are less, some species are more, but not all species perform to the same extent. So we thought if we did that, we could have a molecule that could have, a better outcome for women with advanced-stage ovarian cancer. It turns out in our clinical development that we've now been able to identify that about 80% of platinum-resistant ovarian cancer patients could be appropriate candidates for our molecule.

We've come to that conclusion through the initial clinical development that we've done, most recently in dose expansion, where we demonstrated that women whose expression, regardless of the intensity level, if 25% or more of your cells stain positive for the target, on the tumor slice that we're looking at under an IHC process, then there is a good chance that we're gonna have a benefit for those women, as opposed to, say, 30%, which is on label, for single agent activity for Elahere. So we thought, okay, we've got a broader opportunity than the market opportunity for ImmunoGen. And we might, we believe we have an equal or better drug.

When you look at the data that we have, our response rates, particularly at the higher dose, were in the 40% range, which is a really remarkable response, given the late stage of these women. The duration of response is much better than chemotherapy, which is their comparator standard of care. As we developed the molecule, and now I'll get to the pivotal trial, we thought we had a wide therapeutic window because we started seeing activity, including a complete response, at 2.9 mg/kg, and we were able to dose up to as high as 6.4 mg/kg.

There is an evolving regulatory standard which says that instead of looking for the maximum tolerated dose, for cancer therapies, as has been the case for many years, what we wanna find is the lowest, most effective dose. And the reason for that is that the FDA has come to believe that at these higher doses, you don't get the same bang for the buck that you do if you can optimize the dose. In other words, I get an incremental additional amount of efficacy by pushing the dose high, but that comes at a cost of substantially greater toxicity, and is that extra toxicity worth the burden? So they want companies, including Sutro, to start looking for the lowest effective dose.

And so as we were doing our clinical development and as this regulatory strategy was evolving, we studied in our last study, the dose expansion phase, 5.2 mg/kg and 4.3 mg/kg, sort of within the middle part of the range of where we're seeing efficacy, and at the higher end of the range, we thought that the tolerability was not appropriate, given the efficacy potential that we could see even at that range. So again, we started biasing to understand the lowest effective dose.

We thought we had sufficient data to do so, but in conversations with FDA, they wanted us to start our pivotal trial with an additional 50-patient cohort, 25 at 5.2 mg/kg, and 25 at 4.3 mg/kg, to really have a more complete data set to judge what the lowest effective dose would be, and that would be the dose that would be part of a pivotal trial. So we are in the phase right now where we're enrolling those patients. I should add the 5.2 mg/kg dose is utilized for two doses with the patient, and to control high-grade neutropenia risk. We also give the patients prophylactically growth factor support, because that has been demonstrated to reduce the risk of high-grade neutropenia.

It's not febrile neutropenia, it is really a lab value, but nonetheless, we wanted to add an extra layer of caution, and so for those two doses at 5.2 mg/kg, we supply growth factor support. And then we drop down to 4.3 mg/kg because we came to understand that we believe, based on the data sets that we have, that the higher dose allows you to get more rapid control of the disease burden of the patient. And that's important in late stage ovarian cancer because the patients have been through two, three lines of therapy, and their disease is still relentless. So we wanna get control as rapidly as possible, and we saw that at the higher dose level, we could shrink tumors more rapidly than at the lower dose level.

Now, at the lower dose level, we did shrink the tumors, too, and over time, we got good responses, even at 4.3 mg/kg in the 30% range as well. So we feel like there's a good opportunity between both of those doses. But when you step down from 5.2 mg/kg to 4.3 mg/kg, we noted that you can maintain, that, response that you had previously seen at 5.2 mg/kg. So we felt like trying to balance the safety and efficacy, these additional 50 patients will give us the right additional data to meet FDA's requirements for identifying the least, the lowest, most effective dose. That's called Project Optimus, is the rubric that they are proceeding with.

Once patient 51 comes in, while we're analyzing the data on the first 50 patients, we'll continue those two dose cohorts, and we will add a chemotherapy control arm. Now, we've agreed with FDA that in this trial, we can take the patients who are at the ultimately selected dose, probably somewhere in the 100-patient, 110-patient range or so. We can take those patients, look at the data set, and if it is appropriate, file for accelerated approval. And we believe based on the data sets that we've seen previously, we have a very good chance of having an appropriate data set for accelerated approval. We will also continue, and that will be on the basis of the single agent activity and the safety profile and the durability of response of the selected dose.

FDA, for accelerated approval, uses, you know, a single arm, and then they look at what the chemotherapy control arm, you know, historically has been. So typically, chemotherapy in this stage of patients has about a 12%-15% response rate. And if you're in the, thirty percent or higher response rate, you're, you know, well above what chemotherapy can, give in patient benefit, and the safety profile should be better. And then you wanna have a durability of response, that's at least in the five-month or so, response rate, and chemotherapy has about a 3.5 month response rate. So from that standpoint, we feel like we're setting up well for opportunities for accelerated approval.

Even though we're looking at the data set for accelerated approval, the trial is continuing because at a later stage in the study, we're going to have a full data set that will allow us to apply for full approval, and that will be based on progression-free survival as the primary endpoint, and then overall survival will also be important at that point in time as well. So we've got really one study that has sort of three components to it. Component one is, let's make sure we've identified the optimal dose to meet regulatory requirements. Component two is pulling patients out of the study, analyzing them for purposes of accelerated approval, and component three is continuing that study so that you've got a robust enough data set to apply for full approval. So we've started the trial.

We have centers open, we've got patients done. Sometime next year, when we have a substantial number of centers open, we'll have a better understanding of what our enrollment rates are, and we'll have the ability to talk a little bit about timelines. I would say the thing that I'm encouraged by is that the testing that is done of women today folate receptor-α expression has really allowed more physicians and more patients to understand that there is a targeted therapy that's available for them. And since not everybody is eligible for Elahere, we see that there's a great awareness of our agent. We call it luvelta. There's a great awareness of our agent, and people want to get access to luvelta, and they want to participate in the study. So it's an international study.

It is being run globally. We will get a number of patients from the U.S., but we will get a predominant number of patients, we believe, from outside the U.S. That's really, in a nutshell, what that study is intended to produce for us.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. And just two items I wanted to drill down on, 'cause I think they're important nuances to the Sutro story. One is that second component of the trial that you referenced, and the ability to get accelerated approval, even though there's already a product in Elahere on the market. Could you just take us through how you're thinking about the path to accelerated approval? Is kind of question one. Related to that, I think, is also how you think about enrollment rates, right, in the current trial and the ability to hit your numbers with a product that's already on the market. And I think those two are interrelated. I think they're important parts to this story. Would love to just dig into that nuance a little bit.

Bill Newell
CEO, Sutro Biopharma

Absolutely. So the standard that FDA applies for accelerated approval really is one that focuses on unmet need. And until an agent has full approval, not accelerated approval, but full approval, from a regulatory standard, there is still unmet needs. So today, as we sit here, the platinum-resistant ovarian cancer patient population only has chemotherapy available to it as an approved regimen, fully approved regimen, at this point in time. Ultimately, probably sometime in the next 12 months, we expect that Elahere will get approval, but they will get approval again as a single agent in that high-expressing patient population. So from a regulatory standpoint, the unmet need still exists in the patients who are not high expressors of the target.

And so as we move forward with an accelerated approval request, we will focus predominantly on the patients who have that high- who do not have the high unmet need, who are in this middle ground of having target expression greater than 25% and up to 75%, which is where their threshold starts to begin. So that'll be the focal point of what we get for accelerated approval. Obviously, we will have other patients who have high expression in our study at that point in time, too, and we expect to talk to FDA about the appropriateness of our drug at that level. But the focus for accelerated approval really is gonna be on that unmet need, that 25%-75%, and above 75%, who do not stain with the high intensity that is on label for Elahere.

The other question has to do with enrollment rates, and if we were only going to be doing a study in the United States, upon full approval of Elahere, physicians would find it unethical to potentially give a patient chemotherapy, because that'll be one of the arms of our study as we move forward. And so they might be deterred from enrolling their patients because it's a random choice as to what the patient is treated with. Today, there's not a problem. Elahere does not have full approval, and so a physician in the United States can ethically say, "You're going to get luvelta.

Right now in the first phase, regardless of which arm, you're gonna get a dose of it, either 5.2 mg/kg or 4.3 mg/kg." So the patients are getting a therapy that does have a history of benefiting women. As we move forward, though, expect in the United States, eventually, women who meet that high expression population, once there is full approval, we won't be getting those women in the United States. But full approval in the United States, in the context of a global study, doesn't really impact enrollment because there will not be approval ex-U.S. for an extended period of time.

And even if there is approval, say, in Europe, we all know that reimbursement takes a long time to achieve. So we fully expect that we're in that sweet spot where, we can actually accrue patients, above 25%, in the United States today, and then as the trial, continues to, unfold, we'll be able to supplement that with patients outside of the United States. So let us get, more centers up and running. Let us get a better sense of, you know, how many patients per month, per center we get, and then we'll have a greater ability to guide folks in terms of timing of, study, important study outcome endpoints.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. And how should investors think about the size of the market for high expression versus not?

Bill Newell
CEO, Sutro Biopharma

Yeah. You know, the size of the market has been an interesting question. I think, ImmunoGen has done a nice job in finding women rapidly, and their sales have been, I think, better than people might have thought originally. And so the market really is there. There is a high unmet need. Chemotherapy is not a great option for many of these women, and sometimes women choose, in lieu of chemotherapy, just to go to palliative care, as well. So there's a bigger market than I think people might have thought originally, and ImmunoGen sales numbers suggest that that's gonna be an interesting commercial opportunity, not only for them, but for us.

As I said, 30% of women are on label, or so, are on label for Elahere, and assuming we're able to replicate the datasets that we have previously, we will have a total of 80% of those late-stage patients, so another 40%-50% of patient opportunity, over and above theirs. And if we're competing well in terms of efficacy, and we have a differentiated safety profile, which I should mention, then I think we can even compete robustly in the market that they are presently on label for. Their response rates were in the low 30% range, and I'll make a comment on that in a second. But they also have, as a side effect, ocular toxicity.

And, you know, in the absence of any other therapy, other than chemotherapy, what they've been able to do is really establish that women will tolerate ocular toxicity, which is blurred vision or keratopathy. And you see ocular toxicity with other ADCs as well. It's not every ADC, but many ADCs do have ocular toxicity. Luvelta does not have a safety signal of ocular toxicity, but the women will tolerate the ocular toxicity because they wanna continue to see if they can benefit from the drug. But I think when a choice is given between agents that can be equally effective and the safety profile, one has ocular toxicity, the other doesn't, they would say, well, there's a risk of neutropenia, but the patient doesn't feel the neutropenia. It is not febrile.

We're able to control the risk of high-grade neutropenia, as I said, with growth factor support. The physicians manage neutropenia because the chemotherapy treatments that women are given for the treatment of ovarian cancer and the platinum regimens cause neutropenia. The physicians know how to look for it, know how to monitor it, know how to manage it, and the patient doesn't feel it. We think there's gonna be a really competitive profile for us even in the high patient population. Potentially, the full 80% of platinum-resistant ovarian cancer patients would be available to us from a commercial perspective versus 30%, which is what's on label for Elahere today.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. So very compelling data so far to date. You're enrolling in the next phase of the trial. You've got a large commercial opportunity and the opportunity for accelerated approval as well. Maybe just to finish off on luvelta, a couple other questions here, Bill. I, I know you guys are presenting at ESMO in October. Could you just take us through what you're gonna be presenting on, what investors could look forward to on luvelta? And then, just next clinical milestones as we think about timing, where, where should folks be focused on, on the next data readout?

Bill Newell
CEO, Sutro Biopharma

Yeah. So, we're thrilled that we were invited to do a mini oral presentation at ESMO on our data, our initial data in endometrial cancer. Endometrial cancer is a type of cancer that also is characterized by overexpression folate receptor-α. it's not as widespread, and so when we did the exploratory study in endometrial cancer, which we'll be talking about at ESMO, we wanted to ensure that women who were enrolled in those cohorts had at least some expression level folate receptor-α, and we were trying to identify the right dose again for endometrial cancer as well. So we were looking at a few different doses. So what we have been able to understand, and we'll present the data in a few weeks, is that the drug is active in endometrial cancer.

We will have response data to talk about with respect to endometrial cancer. We've become to understand that, as you might imagine, different levels of expression of the target can lead to different outcomes for the patients. And we've come to really understand a safety profile that is not really materially different from the safety profile we've seen from luvelta to date. So we're gonna talk about how the trial was conducted, what the initial data sets show, but at the outset, I would say that the endometrial cancer data is gonna be something that validates our molecule, because now here's a second solid tumor where we show activity, and we'll talk about that activity, as I said, at ESMO, where we show activity.

I think that's an important hallmark of a true drug, that it can, particularly a targeted therapy, when the target is there, you can have a benefit for the patient. I should add that there's a third indication for our drug. It's a very small, ultra-rare indication, but for those of you who are familiar with the Sutro story, you know that there is a form of AML called the RAM phenotype. It is a really unfortunate phenotype. It affects infants and toddlers. It's mostly diagnosed between the ages of six months and two years, and the prognosis for these patients, even with current AML therapies, is poor. I think only about 15% live beyond two years after diagnosis. What we've been able to do is provide luvelta on a compassionate use basis.

Last year at ASH, our investigator up at Fred Hutch, Dr. Soheil Meshinchi, really profiled 17 of those patients, and almost 50% got into a CR, and I think the majority of those were MRD negative, meaning there was no residual disease that was detectable. And that allows them to have other treatment options, and it was a well-tolerated molecule. So I'm really thrilled that we're starting to really see the full potential of luvelta. There's more to be done with the drug. We anticipate moving forward with a non-small cell lung cancer cohort, probably doing that next year. But we're excited about where we are getting, and when you see multiple tumor types that respond to your therapy, then you know you've got a drug.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. And, and so in terms of just milestones to finish off on luvelta, what should investors be focused on next, and, and what's the timing of your next data readout?

Bill Newell
CEO, Sutro Biopharma

Yeah, I think we really looked at a small number of patients, 15, to really understand the impact of growth factor support in terms of preventing high- grade risk of high-grade neutropenia. We call that cohort, Cohort C. The 15 patients, we reported on 10 of those 15 already. So there's an incremental number five, number of five patients or so that we're gonna be talking about from a safety perspective, predominantly. That's gonna happen later this year. I think the you know, the days of five patients wowing people in our industry are long past us, and I never thought it made a whole lot of sense to judge drug on five patients.

But be that as it may, I think the real, more important endpoint, is gonna be as we get towards, a data set for accelerated approval, and that's gonna take some time. It's not gonna take forever, but it's also not gonna be something that happens this year. So, as we guide to what our enrollment rates are and how we expect to have, data timing, and we'll talk about that more next year, I think that's really what most investors are looking for, is what's the data set, for accelerated approval and when will that be available? So, but in the near term, we will talk about Cohort C and what the, incremental patients, you know, demonstrate for us, particularly from a safety perspective, 'cause that's what that study was designed to do.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Okay. So it's Cohort C, an additional five patients, and then what I'm hearing is no formal guidance yet on the data set for accelerated approval. But maybe talk about, Bill, where you are with your current cash balance in your runway and your ability to get to that next data card flip, the important one that folks are focused on with the cash that you have on hand, including the recent deal that you did with Blackstone.

Bill Newell
CEO, Sutro Biopharma

Thank you. So we've got a t the end of the second quarter, we reported $350 million and change, you know, at Sutro. A big component of that was the $140 million that we'd gotten from Blackstone that you referred to. When we created-- And so let me give a little background about that, and then I'll talk about runway. When we created SutroVax at the time, our hope was that the technology would have a robust opportunity to really change the vaccine space.

I'm thrilled that Vaxcyte, having changed their name just before they went public from SutroVax, has been able to demonstrate that in phase I/ II studies in adults and now moving forward in an infant market study as well. We had a 4% royalty. We also have about 700,000 shares of Vaxcyte stock. As their clinical data evolved, we got inquiries from people who buy royalties as to whether or not we would be interested in selling our royalty. It was 4% on Vaxcyte products that use our technology, and everything that Vaxcyte makes uses our technology.

And so even though it's rare for royalty purchasers to buy assets that are royalties on assets that are other than commercial assets, we sensed that there was a robust interest. We ran a process, and we were able to identify Blackstone as willing to provide what we thought was robust value for the purchase of the Vaxcyte royalties. They gave us $140 million upfront for a molecule that is still three to four years away from the possibility of regulatory approval, let alone commercial sales. And if that molecule proves to be successful, we have an opportunity for an additional $250 million in milestones over time.

So we felt like it was a good opportunity for us to access additional capital in a way that didn't require us to dilute our investors at this point in time. With that funding, we have capital into the first half of 2025 at this point in time. We continue to work on a robust series of business development opportunities, and we've been very good at, I believe, getting good value for people who want to collaborate or partner with us. In the deal that we did with Astellas, which I alluded to earlier, we got $90 million upfront, plus full research support for working with Astellas on up to three programs, going after this immunostimulatory antibody drug conjugate concept. We've started the first program over a year ago.

I'm thrilled that we've now started our second program with them, and looking forward to being able to talk more about that collaboration over time. But this is the third time we've been able to have a successful collaboration with a larger pharmaceutical partner, where we got a substantial amount of money upfront. Our first deal years ago was with Celgene, that over time, brought us over $250 million in monies given to us by Celgene, as part of our collaboration. With Merck, in 2018, we had about $100 million upfront, including a little equity purchased by them, and so now $90 million from our partner with Astellas.

Importantly, in the Astellas deal, we were able to maintain the right to opt in for U.S. rights, on the programs that we're working with them. So we know that there is a significant appreciation within the industry of our platform technology. We know that there is interest in our programs, from a collaboration standpoint, and we know that there's interest in our manufacturing technology as well. So I look to continue to be able to leverage the assets that we have, while maintaining our focus, on driving shareholder value by retaining, to the maximum extent possible, our lead asset. And that's, so it's a long way of saying, yeah, we have capital into the first half of 2025.

I'm confident we're gonna be able to extend that runway to a meaningful endpoint that gets us through an accelerated approval data set. But, you know, let me do a few more things, and I'll come back and tell you what we've done and where that takes the runway.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. So I know we have seven minutes left here. Why don't we talk just briefly about the pipeline? So beyond luvelta, clearly, you've got a validated platform here as well, too, with a lot of interest from external parties. You've got cash runway to see you through to the next value inflection point that investors are focused on with luvelta. How about the CD74- targeting ADC program, STRO-001, as well as your earlier stage ROR1 asset? And especially with ROR1, we've seen a fair bit of activity in the marketplace. We've seen Merck acquire Velos for close to about $3 billion a couple of years ago. So maybe just talk a little bit about what investors should be focused on with those two pipeline assets.

Bill Newell
CEO, Sutro Biopharma

Sure, absolutely. So we started development of STRO-001, our CD74 ADC, looking at both multiple myeloma and non-Hodgkin's lymphoma because the target is expressed in both types of hematologic malignancies. And we thought that there might be interesting data in either or both of those indications. At the time we started those trials, there were other therapies that could potentially benefit patients. I'm gonna say for multiple myeloma, today, you know, there's a lot of attention for B-cell maturation antigen, BCMA, as a target, and we were collaborating with Celgene and then Bristol on that target.

So, that was an important target, and what we came to understand was, there are a lot of competing therapies to treat multiple myeloma patients, and our therapy with a target that we thought was interesting, was sort of relegated to last-in-line therapy, and so we had some challenges enrolling patients. Interestingly, Bristol told us that they've had challenges enrolling patients for their multiple myeloma studies for BCMA as well. So, it wasn't just us. It's, you know, there's a wealth of new modalities and opportunities for patients that makes it challenging at this stage to develop new agents. DLBCL, we had some activity that we reported on, at ASH a few years ago, and we were encouraged, so we continued to progress that program to a point where we had a recommended phase II dose.

But it was still a challenging patient recruitment situation for us. And we had partnered our program with an up-and-coming company in China called BioNova. A number of ex-Celgene Chinese developers and commercial people had founded BioNova, and they have taken our molecule, they've put it in the clinic, and they've started enrolling patients. So we've decided to focus our resources predominantly on luvelta because it is at that most important pivotal trial stage, and then allow BioNova to really focus on developing STRO-001, and then we will pick up the development of STRO-001 once we have additional data from BioNova. So for the time being, we've passed the ball to them, and they're running with it.

The next program you alluded to was, is our ROR1 ADC, and we expect to have that IND on file early next year. We're very excited about this, and, and you referred to the molecule that Merck bought from VelosBio. That is a molecule that really was originally designed and tested in hematologic malignancies, and we know that it had good data in the heme space, but that the real commercial potential is more in the solid tumor space. And, and Merck has certainly embarked on a series of studies in the solid tumor space. We are waiting and watching for their readouts to understand how this molecule performs in that space.

Interestingly, you know, a molecule that is designed for the hematologic malignancy, for the treatment of hematologic malignancies, may not have all of the characteristics that you want, in a molecule that's going to be treating solid tumors just because of the differences in target accessibility, the ability to penetrate cells, et cetera, in a solid tumor environment. And so we set out to actually design a next-generation ROR1 ADC that was specifically designed for the solid tumor market. And so we've got a new linker and a new warhead. This is the third linker and third warhead that we've now been working with. The warhead is a particularly exciting one. It's an exatecan warhead.

This is the same class of molecule that is on Enhertu, which is, a great Daiichi molecule, and really it represents an advancement, I think, in our ADC understanding of how to get the right killing modality attached to an antibody drug conjugate. We're also using a new, type of linker, called the β-glucuronidase linker, that has even greater stability before it gets into the tumor microenvironment and gets cleaved, and so limits the risk of off-target toxicity, even more. So we're combining advances that we and others in the industry have identified, and we've got some really exciting, preclinical data, on ROR1, which suggests that we can have good disease control in heterogeneous, tumor types, solid tumor types, as well as those that have low expression.

Importantly, though, the toxicity profile is really been minimized to a great extent, and so we don't see a lot of the traditional toxicities that you see with an exatecan class warhead, even at doses we've seen up to 45 mg/kg. So, we're excited by the safety profile of this molecule, as well as by the initial efficacy, and look forward to moving that into the clinic, as I said, early next year.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. So maybe in closing here, Bill, I'll just kind of recap and let me know if I'm missing anything. So investors, in terms of where they should be focused for Sutro going forward in the next six to 12 months, you've got a presentation at ESMO. You have your Cohort C luvelta data or update there on the additional patients. You then have an IND filing in the first half of next year, early next year, for your ROR1 asset. And importantly, you have the cash runway to get through to your next value inflection point for luvelta, which is gonna be the dataset for potential accelerated approval. Is that the right way to think about it?

Bill Newell
CEO, Sutro Biopharma

We're working hard on all of that and trying to accelerate as much as possible. I do believe you'll see other things that we do to generate additional capital for the company, but I'm not gonna project that. You know, with $350 million in the bank, I don't really need to be worried immediately today, but I'm always worried about capital and trying to find the most efficient way, without accessing the public markets too heavily, to continue to fund the company to meaningful value inflection points. We also have some stock from Vaxcyte that, at an appropriate point in time, we can liquidate. And you know, I'm still optimistic that our friends at Merck will present data at some point on our IL-2 derivative.

Andrew Pucher
Managing Director and Head of West Region Healthcare Investment Banking, Citi

Great. Thanks for your time, Bill.

Bill Newell
CEO, Sutro Biopharma

Thank you so much, Andrew.

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