Scholar Rock Unveils Preclinical Data on SRK-439 Showing Increased Lean Mass and Fat Loss with Metformin

Scholar Rock, a late-stage biopharmaceutical company specializing in innovative treatments for serious diseases such as spinal muscular atrophy (SMA) and cardiometabolic disorders, has unveiled encouraging preclinical data for SRK-439. This investigational antimyostatin antibody appears to increase lean mass and decrease fat mass gain when administered with metformin. These findings will be presented by Melissa Fulham, Ph.D., at the upcoming ObesityWeek conference in San Antonio, Texas.

The latest data reinforces the potential of selective myostatin inhibition as a promising therapeutic strategy, according to Jay Backstrom, M.D., MPH, President and CEO of Scholar Rock. He highlighted that the new results support the hypothesis that targeting myostatin with precision could positively impact body composition in individuals suffering from obesity and related conditions like diabetes. This underscores the value embedded in Scholar Rock’s platform. He also mentioned plans to update on the cardiometabolic program's progress, including Phase 2 EMBRAZE trial topline data expected in mid-2025.

The preclinical study involved testing a murine version of SRK-439 in a diet-induced obesity (DIO) mouse model. Mice were fed a high-fat diet and subsequently given either metformin or water for four weeks. Following this, they received either an IgG control antibody or SRK-439 for another four weeks. The study was conducted on both young and mature mice to observe age-related effects. The analysis included measuring changes in lean mass using quantitative nuclear magnetic resonance (qNMR).

Key findings from the study indicate that mice treated with SRK-439 and metformin showed a substantial increase in lean mass compared to those treated with metformin alone. This outcome was consistent across different age groups. For example, young mice treated with SRK-439 and metformin exhibited a twofold increase in lean mass compared to the metformin group and IgG controls. In older mice, the increase was even more pronounced, with a 50-fold rise in lean mass for the SRK-439 group compared to the control group.

Additionally, young mice receiving the combination of SRK-439 and metformin experienced a lower fat mass gain than those treated with metformin alone. In older mice, a trend towards reduced fat mass gain was observed with the combination treatment compared to metformin alone, although it was not statistically significant.

Mo Qatanani, PhD, Chief Scientific Officer at Scholar Rock, emphasized that these preclinical data demonstrate the potential of selectively inhibiting myostatin to increase lean mass, particularly in older mice who are typically more weight-stable. Furthermore, the combination of SRK-439 and metformin in younger mice resulted in a greater reduction in fat mass gain compared to either treatment alone. This compelling evidence suggests that SRK-439 could improve body composition and support healthier weight management, particularly in the context of obesity and type 2 diabetes.

The findings will be presented in a poster session titled "SRK-439 Selectively Inhibits Myostatin to Promote Healthy Body Composition During Metformin Therapy" by Melissa Fulham, Ph.D., on November 5, 2024, at the Henry B. González Convention Center in San Antonio, Texas.

SRK-439 is an investigational myostatin inhibitor that targets pro- and latent myostatin with high affinity and specificity, initially being developed for cardiometabolic disorders including obesity. Current preclinical data suggest it could support healthier weight management by preserving lean mass during weight loss. However, its efficacy and safety are yet to be established, and it has not received approval from regulatory authorities.

Scholar Rock continues to be a leader in developing treatments for severe diseases with significant unmet needs. Their focus on innovative therapies targeting protein growth factors holds promise for transforming care in various conditions, including neuromuscular diseases, cardiometabolic disorders, and cancer.