Jay Backstrom
Analyst · Piper Sandler. Your line is open
Well, thank you Tracey. And now turning to our cardiometabolic programs and moving to slide 13. It's impressive to see the impact of the innovation from our industry and how the approved GLP-1 receptor agonists have transformed the management of weight loss. Obesity is a top global public health issue and the potential public health impact of these highly effective weight loss therapies have been incredible across a number of chronic conditions including diabetes, sleep apnea and cardiovascular disease. With an estimated 40 million projected to receive treatment GLP-1 receptor agonists, the current market is anticipated to generate over 100 billion in sales. Moving to slide 14. With the extraordinary amount of weight loss seen with the current GLP-1 receptor therapies, there's also a substantial amount of lean muscle that is also lost, ranging from 12% to 40%. With the widespread use of these therapies, there's an increased awareness of the associated weakness and reduced strength that accompanies this loss of lean muscle mass and of the significant weight regain that occurs when stopping therapy with disproportionately more fat being regained than lean mass, leading to a worse body composition and leading to unhealthy weight gain. Beyond strength and mobility, muscle is the main metabolic organ and plays a significant role in energy metabolism, increasing basal metabolic rate, glucose uptake and improving insulin sensitivity. Given the critical role that muscle plays in overall health, we believe our highly selective approach to blocking myostatin when added to the GLP-1 receptor agons can enhance their profile by reducing the loss of lean muscle mass without introducing additional toxicities leading to healthy and sustainable weight management. Moving to slide 15 to illustrate what can be expected from Tirzepatide, this figure is from the Tirzepatide SURMOUNT-1 study and illustrates the percent change in body weight over time. The area shaded in green represents the first 20 weeks of the study, the time period corresponding to the efficacy assessment in EMBRAZE, our randomized Phase 2 group of concept study with Tirzepatide. As can be seen, even by week-24, there's an impressive amount of weight loss of 14% to 16% of body weight that continues to deepen over the course of 72 weeks. Approximately 25% of this weight loss is lean mass, an area that we believe we can address through our highly selective approach to blocking myostatin, the master regulator of skeletal muscle. By preserving lean mass and reducing the amount of lean muscle mass lost, it can lead to healthier and sustainable weight loss and potentially change the treatment paradigm for weight loss management. Now moving to slide 16. So what does preserving lean muscle mass mean with respect to clinical benefit and what amount is needed to have a meaningful impact? Well, insights can be gained from a study of healthy young men who were confined to strict bed rest for one week and lost about a kilogram of lean mass as assessed by DEXA scans. Remarkably, the loss of just 1 kg of lean mass resulted in significant decrease in leg strength, exercise capacity and equally importantly, in insulin sensitivity compared to baseline. Considering that adults over 60 begin to lose 1% of lean mass per year with a 10% to 15% decrease in strength per decade, the additive effect of loss of lean mass associated with GLP-1 receptor therapy in this age group and other subsets can be profound. Now Moving to Slide 17. With respect to EMBRAZE, we had several key goals in mind when we designed EMBRAZE, a randomized Phase 2 proof-of-concept study comparing Tirzepatide plus apitegromab to Tirzepatide plus placebo in obese overweight adults. First, with respect to preserving lean muscle mass, we believe we can reduce the amount of loss as measured by DEXA scans at week 24 with our highly selective approach to blocking myostatin. We selected week 24 as the time point to assess since this was the steepest portion of the weight loss curve with Tirzepatide. Recognizing that, we'll need to assess week-52 for our SRK-439 program. As a proof-of-concept study, we're looking for trends in the magnitude of effect to help shape our thinking regarding clinical meaningful improvement. Extrapolating from the study in young men, assuming a loss of lean mass between 4 kg to 5 kg, by reducing the amount of lean mass loss by 20% to 40%, we can preserve 1 kg to 2 kg of lean mass, which we believe will translate into clinical meaningful benefit since every kilogram of lean muscle mass matters. Second, based on our selective approach, one of our goals was to demonstrate that we can safely combine Tirzepatide and not introduce any additive toxicity that can be associated with blocking other TGF beta ligand such as actin. Third, with respect to weight loss at week-24, we are expecting to see comparable weight loss at this time. Fourth, based on our non-clinical data, we believe we can blunt the fat regain associated with stopping Tirzepatide and have built in an additional DEXA scan performed eight weeks after stopping treatment to assess this important question. These data will not be part of the top line results that we look forward to sharing next quarter. Fifth, as a proof-of-consult study we're also included exploratory endpoints such as hemoglobin A1C and functional measures, but we did not power or enrich the study with subsets of patients to show statistical significance for these exploratory endpoints. And then finally, an important key goal is to is for us to gain experience in the setting of obesity. We'll have the opportunity for detailed review of all the EMBRAZE subject data to identify subgroups and to help inform the clinical development of SRK-439, a highly selective anti myostatin designed for cardiometabolic disorders. We've already shown our ability to deliver EMBRAZE ahead of schedule and this experience provides us with great momentum for SRK-439 program. Moving to slide 18 and with respect to SRK-439 we are very excited with the data that's been generated to date in our non-clinical program demonstrating we can preserve lean mass with further reduction in fat mass we can improve metabolic parameters such as blood glucose. We've seen increase in lean mass gain and once the fat regain of fat mass after stopping the GLP-1 receptor agonist therapy and we've demonstrated greater potency in a direct comparison with anti-ACTRII antibody. Overall, the data suggests the best in class profile for SRK-439 which has been featured at key scientific conferences in 2024 and we look forward to bringing SRK-439 to clinic later this year. Moving to slide 19. In summary, to address the important emerging problem of loss of lean mass associated with weight loss therapies, we've taken a parallel path with our innovative industry leading portfolio of highly selective anti myostatin therapies by conducting a proof-of-concept study with Apitegromab EMBRAZE and at the same time advancing SRK-439 to IND or highly selective novel antimyostatin designed specifically for cardiometabolic indications, With the ambition to transform the current GLP-1 receptor agonist treatment therapy. This strategy has resulted in two important milestones in 2025 and we look forward to the readout of the top line data for EMBRAZE next quarter and the filing of the IND for SRK-439 in Q3. In closing and moving to Slide 21, 2025 will be a transformative year for Scholar Rock. We are off to a great start. We've submitted the BLA for apitegromab in the U.S. in January. We're on track to submit the MAA in the EU in March. We were well on our way in our preparations to bring apitegromab Muscle Targeted Therapy, potential new treatment option for those living with SMA globally starting in the U.S. in Q4 with EU to follow in 2026. As we continue to work to expand our reach to the youngest of those with SMA and to other rare neuromuscular disorders, we are on the threshold of establishing a neuromuscular franchise starting with SMA. We look forward to reporting on our progress toward achieving our 2025 key milestones as we drive to commercialize and expand the development of apitegromab and advance our cardiometabolic programs. Overall, a very, very exciting year for Scholar Rock. And operator that closes the prepared remarks. We'll now open up the call to questions.