Scholar Rock Holding Corporation (NASDAQ:SRRK) Q3 2023 Earnings Call Transcript

Scholar Rock Holding Corporation (NASDAQ:SRRK) Q3 2023 Earnings Call Transcript November 7, 2023

Rushmie Nofsinger: Good morning. I’m Rushmie Nofsinger, Vice President of Corporate Affairs and Investor Relations at Scholar Rock. Welcome, and thank you for joining us today for our Q3 2023 Business Update Call. This call is audio-only. You can access the slides that we’ll be referring to on the Events and Presentations section of the Investor Relations page on the Scholar Rock website. Moving to Slide 2. Before we begin, I want to note that we’ll be making various statements about Scholar Rock’s expectations, plans and prospects that constitute forward-looking statements for the purposes of the safe harbor provisions under the Private Securities Litigation Reform Act of 1995. Any forward-looking statements represent our views only as of today and should not be relied upon as representing our views as of any future date.

Please refer to our SEC filings for the full disclosure of all the risks. Turning to Slide 3. I’d like to introduce the members of the Scholar Rock team, who will be presenting during today’s call and will be available for questions after the conclusion of the formal remarks. I am joined by Jay Backstrom, CEO of Scholar Rock; Ted Myles, Chief Operating Officer and Chief Financial Officer; and Mo Qatanani, Head of Research. I will now turn it over to Jay.

Jay Backstrom : Thank you, Rushmie, and good morning, and welcome to our Q3 business update call. We’ve made excellent progress so far this year and in particular, in the third quarter, and I’m very excited about our future and believe we are well positioned for success. Moving to Slide 4. Before I review the details of our progress, I want to start with Scholar Rock’s pioneering approach to targeting TGFß super family of growth factors. The picture on the left of the slide depicts the latent complex that contains an active growth factor. The scientific insight that led to the understanding of the structure of this latent complex is part of the foundation of our industry-leading platform that targets TGFß superfamily of growth factors by selectively and specifically blocking their activation by locking up the growth factor in the precursor or latent form.

This highly specific approach limits the off-target effects that have been observed with less selective approaches that target the active forms of the growth factors or interfere with their receptors such as the activin receptors. Apitegromab, our lead clinical program targeting latent myostatin prevents the formation of the active form of myostatin, a negative regulator of muscle growth and leads to an increase in muscle mass and function in non-clinical models and is the first anti-myostatin therapy to demonstrate clinical proof-of-concept. Moving to Slide 5. I was very excited to announce that we are leveraging our R&D platform and deep knowledge of myostatin biology to expand into a new therapeutic area of cardiometabolic disorders with our novel, highly potent and selective anti-myostatin antibody SRK-439 in combination with the GLP-1 receptor agonist.

Scholar Rock has a long-standing interest in targeting myostatin for cardiometabolic disorders, given the role that muscle plays in glucose metabolism and insulin sensitivity. As you’ll hear from later in this morning’s presentation, our approach to blocking myostatin is ideally suited for use in both SMA and in cardiometabolic disorders since by blocking myostatin and only myosin, we avoid off-target toxicities. Safety is critically important in treating SMA and in weight loss therapy, and we believe our selective approach, as we’ve seen with apitegromab in our SMA program to-date, should lead to a favorable overall benefit risk profile. Moving to Slide 6. Targeting the TGFß superfamily has broad therapeutic applications given the central role this family of growth factors plays in wide range of cellular processes, including growth and differentiation.

Our research teams have produced a robust pipeline of product candidates targeting latent myostatin and latent TGFβ1. I’m very pleased with the significant progress that we’ve made on our pipeline since the beginning of the year. Moving to Slide 7. For this morning’s call, I will start with an update on our clinical programs, highlighting the status of SRK-181, our selective anti-latent TGFβ-1 antibody in Immuno-Oncology followed by an update on the progress we’ve made with our number one priority, apitegromab and SMA, and then turn to Mo to discuss our entry into cardiometabolic disorders with our novel anti-myostatin SRK-439. Moving to Slide 8. Slide 8 provides an overview of the DRAGON drop. As a reminder, the main objectives of the DRAGON study, in addition to dose ranging and safety, included establishing proof-of-mechanism and proof-of-concept that by blocking TGFβ1, a key driver for resistance to checkpoint inhibitors with SRK-181 in combination with pembrolizumab and that we could overcome the immunosuppressive environment and restore responsiveness to the checkpoint inhibitor.

To achieve these objectives, the Part B portion of the study included expansion cohorts in several tumor types and required all patients to have progressed on the most immediate prior anti-PD-1 or PD-L1 treatment. The study is rich in biomarkers, including paired biopsies to assess if SRK-181 could overcome an immune exclusion phenotype and drive CD8+ T Cells into the tumor, as was demonstrated in our non-clinical models. The team made excellent progress with the DRAGON study since the start of the year, culminating in two poster presentations at the Annual Meeting of the Society for Immunotherapy of Cancer, this past weekend. The first poster focused on biomarker data in support of proof-of-mechanism. And the second provided a clinical and biomarker update from the renal cell carcinoma cohort from the Part B expansion, the cohort with the most patient data, including follow-up.

I will start with a review of the biomarker poster. Moving to Slide 9. This poster focused on biomarker data and support of proof-of-mechanism. And based on paired biopsy data demonstrated that SRK-181 in combination with an anti-PD-1 therapy increased the infiltration of CD8+ T Cells across several tumor types, including melanoma, shown here. This was seen in the compartmental analysis that measures the percentage of CD8+ Cells in the tumor – Tumor Margin in Stroma from 2 melanoma patients. As shown on the graph on the left, there was an increase in CD8+ T Cells observed after treat overcoming an exclusion or desert phenotype, which was present at baseline. Similarly, as shown in the histopath image on the right, there’s an increase in intensity of brown staining, representing CD8+ T Cells in the post-treatment biopsy, also demonstrating the influx of CD8+ T cells into the tumor.

We were excited to see these data, which essentially reproduced the non-clinical findings that form the scientific rationale for SRK-181. Turning to Slide 10. The second poster presented at SITC provided an update on the renal cell carcinoma cohort from Part B. Overall, 28 patients were evaluable for response. It’s important to note that the patients enrolled represented a heavily pre-treated population, who received the meeting of three prior lines of treatment, including a checkpoint inhibitor and tyrosine kinase inhibitor. All had disease progression on their prior anti-PD-1, PD-L1 treatment. This slide includes, three graphical displays from the poster and highlight the treatment duration, as shown in the swimmers plot, antitumor activity, as shown in the waterfall plot and the spider plot that illustrates both duration and tumor response.

As can be seen, there is clear evidence of tumor reduction with a 21% overall response rate, that is durable beyond six months and a disease control rate of 57%. The overall response rate is significantly above what we would expect from a checkpoint inhibitor alone, in the setting of prior anti-PD-1/PD-L1 progression, which is expected to be less than 5%. With respect to safety, the combination was generally well tolerated with the most common Treatment Emergent Adverse Events, predominantly skin toxicities, of rash and pruritus. Moving to Slide 11. In summary, the DRAGON trial delivered on its objectives of showing Proof of Mechanism and Proof of Concept with promising overall response rates in a heavily pretreated relapsed/refractory, patients’ with clear cell renal carcinoma, all who progressed on prior treatment with a PD-1 or PD-L1 therapy.

Now the Dragon has met its objectives, we plan to enclose enrollment in December, begin closeout activities while we continue to treat those patients who continue to benefit from therapy and remain on study. We also plan to present ongoing data from Dragon, at future medical meetings. We would like to take this opportunity to thank the investigators, the study staff and in particular, the patients and their families who participated in or are currently, participating in Dragon. Regarding the SRK-181 program overall, we believe the data from Dragon support advancing the program, and we plan to conduct an end of Phase 1 meeting with FDA in the first half of 2024 to determine the next steps. Turning to Slide 12, I’ll now focus on our lead clinical program with apitegromab in Spinal Muscular Atrophy or SMA.

As a reminder, SMA is an inherited neuromuscular disorder, caused by a deficiency in a protein, the SMN protein that is essential for The survival motor neuron, which in turn is responsible for controlling muscle movement. When the SMN protein is deficient, the motor neuron degenerates resulting in muscle weakness in atrophy, leading to significant impairments, including the inability to sit, stand and walk depending on the extent of involvement. Currently, there are three approved therapies for SMA, all work to increase the amount of SMN protein, but none target the muscle directly. Apitegromab, by targeting latent myosin prevents the formation of the active form of myosin, a negative regulator of muscle growth and is the first antimonite resulting in improvements in motor function, as shown in our Phase 2, Proof-Of-Concept Study TOPAS.

Moving to Slide 13. As we shared at the 2 SMA, event in June, we were excited to present 36-month data from the pooled non-ambulatory patients from TOPAS, the same patient population included in our Phase 3 registration study, SAPPHIRE. As shown, there was robust, consistent and sustained improvement in the motor function scales, the extended Hammersmith and The Revised Upper Limb Module, which are also the primary and secondary endpoints in SAPPHIRE as well as improvements in the patient reported outcome measures, as reflected in an increase in activities of daily living and reduction in fatigue all measures that are consistent with improvement in muscle strength. Turning to Slide 14, I’m very pleased with the progress we’ve made this year toward executing on the promise of apitegromab in SMA.

We have met or are on track to meet all of the 2023 goals for the program that we outlined at the beginning of the year. In addition to reporting the 36-month TOPAZ data in June and 2 SMA, we also opened the Onex long-term extension study, which will serve as a platform for patients from both TOPAZ and SAPPHIRE to continue to receive apitegromab. Importantly, Onex provides an opportunity to further strengthen the body of evidence on long-term safety and efficacy. As we announced in September, we completed enrollment of our Phase 3 registration study, SAPPHIRE, a major milestone for the study and look forward to reporting our top line results in Q4 2024. Assuming success and regulatory approval, we expect to be a commercial company in 2025. And from a commercial perspective, the launch of apitegromab will be leveraged by the established SMA market.

And finally, our team is in the planning stages for additional follow-on SMA studies, including in children under the age of two, and in ambulatory patients, allowing us to extend the potential benefit of apitegromab to the broadest patient population possible. Now moving to Slide 15. And I’d like to turn this portion of the program over to Mo, who will provide an overview of the cardiometabolic program. Mo is the Head of Research and brings a wealth of experience in both neuromuscular and cardiometabolic diseases. As I mentioned in my opening remarks, Mo’s team has been working on targeting anti-myostatin for cardiometabolic diseases for quite some time, and Mo will walk you through this research. Mo?

Mo Qatanani: Thank you, Jay, and good morning, everyone. Now on slide 16. Our approach of targeting the pro and latent forms of Myostatin allows us to have exclusive selectivity to inhibit Myostatin signaling and nothing else. A nonselective approach that targets pathways outside of Myostatin or muscle has the potential to have deleterious effects. For example, inhibition of the closely related GDF11 growth factor signaling may have negative impacts on bone an inhibition of activins has demonstrated effects on reproductive biology likely limiting the use of products, which target this pathway in women of child-bearing age. By inhibiting Myostatin and only Myostatin, our antibodies provide a profile that drives efficacy without the potential liabilities that come with nonselective approaches, which is critical, especially in this patient population.

We are now on slide 17. Obesity is recognized as a top global public health challenge with an estimated $1 billion adults worldwide, including half of the population the as projected to be abused by 2030. This is associated with several serious comorbidities like heart disease and type 2 diabetes and staggering cost to the health care system. Weight loss by any means leads to loss of not only fat but also lean mass and this is evident in the GLP-1 receptor agonist mediated weight loss that are experiencing rapid uptake and where lean mass losses may be 25% to 40% of the total body weight loss. Loss of lean mass is a key predictor of adverse outcomes in older patients and maintaining lean mass through exercise during rate loss has demonstrated longer-term benefits versus weight loss alone.

Therefore, it is possible that maintaining lean mass in the context of weight loss may promote additional fat loss as well as greater long-term metabolic benefits. Moving to slide 18, where we’ll be discussing SRK-439. SRK-439 is a novel preclinical antimyostatin antibody that is in development. As mentioned earlier, we leveraged our extensive expertise in myostatin structure and biology to develop this molecule to specifically address the patient population of codomibolic disorders. SRK-439 has attractive properties and potential to address the muscle loss associated with weight loss. It has high end mutual affinity for pro and latent myostatin to potentially lead to efficacy at lower doses It maintains myostatin specificity with no GDF11 or active in a binding to limit any potential undesirable off-target effects, especially in this patient population.

It also maintains a good developability profile, and is amenable to subcutaneous formulation and dosing. Now on Slide 19, where we show our efficacy data with SRK-439 in combination with GLP-1 receptor agonist in diet-induced obesity mass model, a standard model used in the field. As expected, the decrease in body weight induced by GLP1 receptor agonist, liraglutide in this case, led to a decrease in not only fat mass, but also lean mass, as you see with the TAM bar. Combining SRK-439 with a GLP-1 receptor agonist confirmed our therapeutic hypothesis and led to a dose-dependent reversal of lean mass loss in addition to enhancement of fat mass loss Now on Slide 20. Slide 20 highlights the efficacy of SRK-439 in diet-induced obesity mouse model in combination with semaglutide and more effective GLP-1 receptor agonist.

Semaglutide did lead to significant loss of lead mass in addition to fat mass loss as seen in the TAM bar. However, when combined with SRK-439, the loss in lean mass induced by semaglutide alone was dose-dependently reversed, leading to maintenance of lean mass while enhancing fat mass loss. It is worth noting that we see lean mass reservation with doses as low as 0.3 milligram per kilogram of call SRK-439, which highlights the favorable profile of SRK-439 for development in this indication. Turning to Slide 21. To summarize, our approach is explicitly selective in targeting myostatin and myostatin only and avoids potential liabilities of our target inhibition. The selective inhibition of myostatin in combination with GLP receptor agonist driven weight loss may lead to healthier, more durable weight management, and we look forward to testing this in the clinic.

Now on Slide 22. In summary, our preclinical data supports advancing SRK-439, a novel investigational myostatin inhibitor for the treatment of cardiometabolic disorders with initial focus on obesity. We are moving SRK-439 towards IND submission in 2025. To inform the development of SRK-439, we plan to initiate a Phase 2 proof-of-concept trial of a particular map in combination with GLP-1 receptor agonist in obesity in 2024. The data readout of that trial is expected in mid-2025. Now I will turn it over to Ted for summary.

Ted Myles: Thanks, Mo. Moving to Slide 24. 2023 has been a year of significant execution across our portfolio, and we’re well positioned going into 2024. We’re seeing great productivity coming out of our scientific platform as our unique approach of targeting the latent form of growth factors to achieve exquisite selectivity appears to be proving patient outcomes in SMA and in oncology. We are excited to be applying this selectivity to our cardiometabolic disease areas where we believe safety is so important, and our approach is highly differentiated. Our upsized public offering that we completed last month puts us in a strong financial position with our cash runway that extends into the second half of 2025. We’re focused on advancing the myostatin programs, SMA and cardiometabolic Additionally, we believe we’re well positioned to bring in nondilutive funding as we continue to evaluate potential partnership opportunities for other programs within our portfolio.

We view strategic business development as an important way to advance promising programs by leveraging the infrastructure, capital and expertise of other companies. We ended the third quarter with $219 million of cash and cash equivalents, and our October capital raise netted approximately $93 million. Our capital allocation strategy includes a substantial reduction in our spend on SRK-181 as we complete enrollment of DRAGON and continue to support remaining patients on study. Our primary focus as we conclude 2023 and look to 2024, includes investments to advance apitegromab in SMA and our newly announced cardiometabolic program. With the capital enhance, promising programs underway and our strategic imperatives aligned with our core competency, unparalleled selectivity of myostatin inhibition, we are excited about the future and our ability to serve patients with our important novel therapies.

This concludes our formal remarks. I’ll now turn it over to the operator, so we can start the Q&A. Operator?

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Q&A Session

Operator: Thank you. The floor is now open for your questions. [Operator Instructions] Your first question comes from the line of Michael Yee with Jefferies. Your line is now open.

Michael Yee: Hey, guys, thanks for the question, and congrats on all the progress. We had two questions. One on SMA and one on cardiometabolic. SMA, in your Phase 3, I believe the primary analysis is based on two to 12, and I was wondering if you have any thoughts around the proportion of the study that is probably more two to five versus, say, older, and whether there is any pre-specified analysis that has an analysis to look at the younger patients versus the older patients in that study after observing what happened with DMD gene therapy and how that played out if there’s a pre-specified analysis for younger patients? And then on cardiometabolic, an interesting hypothetical question, I appreciate that this is an obesity drug that you’re trying to develop, do you anticipate that the regulatory path is traditional obesity just weight loss, whether there’s an endpoint also that would be accepted by the FDA for muscle gain, and I was wondering how you think about that?

Thank you.

Jay Backstrom: Yes, great. So Michael, thank you. This is Jay. Thanks for the question. Let me start with the SMA. So yes, our primary analysis is the two to 12. We haven’t disclosed the proportion of that group who are between the ages of two and five. And at this juncture, our primary analysis and pre-specified analysis certainly include the older cohort, but as you know, upon top line data, we have the opportunity to look across the age groups. So we will certainly look at that in the top line results. So I think that took care of the question on the SMA patient population. With respect to cardiometabolic, yeah, very interesting question. I think with respect to the current approval for weight loss, it is the amount of weight loss that occurs that is the primary endpoint, as you know, this is an evolving field.

And I think recognizing that the need to preserve lean muscle mass is really critical, and the efforts now that we’re in and others are in, I think will help inform future regulatory endpoints, but we will need to demonstrate at some point across the program improvements in either function or patient-reported outcomes. So I think that will need to be a standard part. But I think it’s a stay tuned as I think as we move forward. For our proof-of-concept study, we’re certainly going to be focused on demonstrating that we can preserve and maintain the muscle mass. I think for a proof-of-concept, that’s mechanistically sound, and that’s our approach going forward.

Michael Yee: Thank you, guys.

Operator: Our next question comes from the line of Allison Bratzel from Piper Sandler. Please go ahead.

Allison Bratzel: Hi, good morning team. Thanks for the update today, and thanks for taking my question. So first, on SRK-439, maybe a question for Mo. Could you just provide some more color on the different properties of 439 compared to apitegromab, and just really distill for SY 439 is better suited to go forward in obesity. It seems the subcu format is a major differentiator there. Just curious if subcu administration of apitegromab is something you’ve explored. Any color there would be helpful. And then, just on a related note, could you help us understand what is gating to IND filing for apitegromab in obesity? And also, same question, what’s gating to IND filing for 439 and what gives you confidence that IND filing will be ready to go in mid-2025? Thanks.

Jay Backstrom: Hey Ally, this is Jay. Maybe I’ll take one part of that three-part question, and then I’ll turn it over to Mo. And there’s the question around the IND, what’s required to get the IND filed for apitegromab. Why I’m really delighted that we have the opportunity to proof-of-concept with apitegromab is because it’s already a clinical-stage asset. So it’s a matter of really putting together the scientific rationale and submit the IND for a new division to agree and we get to cross reference a lot of the existing documents in the current apitegromab’s IND and SMA. So it’s really a matter of kind of completing the regulatory dossier to do that and then engage FDA. So that work, frankly, we had started even prior to announcing our going into this area. And then maybe I’ll let Mo talk about the IND-enabling work required for SRK-439 and then more details.