Stanford Medicine Researchers Uncover Potentially Game-Changing Appetite-Suppressing Molecule, BRP, Showing Promise Beyond Semaglutide

Stanford Medicine researchers have identified a naturally occurring molecule that may suppress appetite and reduce body weight in a way that resembles semaglutide, the active ingredient in Ozempic. In animal studies, the molecule also appeared to avoid several problems associated with the drug, including nausea, constipation and substantial muscle loss. The discovery, detailed in a groundbreaking study published on March 5 in the prestigious journal Nature, could pave the way for a new generation of weight management therapies with potentially fewer side effects.

The newly identified molecule, dubbed BRP (BRINP2-related-peptide), operates through a distinct yet related metabolic pathway compared to semaglutide. While semaglutide mimics the effects of glucagon-like peptide 1 (GLP-1), a hormone that influences appetite and blood sugar, BRP appears to target a more specific region of the brain. This crucial difference may allow for a more precise control over appetite and body weight, potentially circumventing some of the systemic effects that lead to undesirable side effects in current treatments.

A More Targeted Approach to Appetite Control

Katrin Svensson, PhD, an assistant professor of pathology at Stanford Medicine and senior author of the study, explained the significance of BRP’s unique mechanism. "The receptors targeted by semaglutide are found in the brain but also in the gut, pancreas and other tissues," Svensson stated. "That’s why Ozempic has widespread effects, including slowing the movement of food through the digestive tract and lowering blood sugar levels. In contrast, BRP appears to act specifically in the hypothalamus, which controls appetite and metabolism."

The hypothalamus, a small but critical region deep within the brain, serves as the body’s central regulator for a myriad of essential functions, including hunger, body temperature, hormone activity, and overall energy utilization. By concentrating its action primarily in this area, BRP holds the potential to influence appetite and metabolism without eliciting the broader, and sometimes problematic, effects observed with drugs that act on more widely distributed receptors. This specificity is a key factor that has generated significant excitement within the scientific community.

Recognizing the immense potential of BRP, Svensson has co-founded a company that is actively preparing to initiate clinical trials in human subjects in the near future. This rapid progression from animal studies to human testing underscores the urgency and optimism surrounding this discovery. Laetitia Coassolo, PhD, a senior research scientist at Stanford and lead author of the Nature study, emphasized the collaborative nature of this research.

Artificial Intelligence Unlocks Hidden Peptides

The discovery of BRP was not a matter of serendipity but a testament to the power of cutting-edge computational tools. The researchers heavily relied on artificial intelligence (AI) to sift through a vast landscape of proteins, specifically targeting a class known as prohormones.

Prohormones are essentially inactive precursor molecules that require enzymatic cleavage to release smaller, biologically active fragments called peptides. These peptides then function as hormones, transmitting vital signals that regulate complex physiological processes, including metabolism and appetite, throughout the brain and body. The challenge lies in the fact that a single prohormone can be processed in numerous ways, yielding a multitude of peptides, many of which are mere byproducts of normal protein turnover and lack significant biological function. Identifying the truly impactful peptide hormones among this deluge of molecular fragments has historically been an arduous and data-intensive endeavor. Traditional laboratory methods, while effective, can generate enormous datasets, requiring researchers to manually analyze hundreds of thousands of molecules to pinpoint those with meaningful biological activity.

Searching for New Metabolic Signals with Precision

The Stanford team focused their investigation on an enzyme called prohormone convertase 1/3 (PC1/3). This enzyme plays a critical role in cleaving prohormones at specific amino acid sequences and has previously been implicated in human obesity, making it a logical starting point for the search for novel appetite-regulating molecules.

Crucially, one of the peptides generated by PC1/3 is glucagon-like peptide 1 (GLP-1), the very peptide that semaglutide emulates. The researchers hypothesized that PC1/3 might also be responsible for producing other peptides that exert influence over energy balance and appetite. To test this hypothesis and navigate the complexity of prohormone processing, they turned to AI.

Peptide Predictor: A Novel AI Tool

Instead of relying solely on conventional methods of extracting and analyzing peptides from biological tissues, which can be time-consuming and prone to overwhelming data volumes, the researchers developed a sophisticated computer algorithm named "Peptide Predictor." This AI-powered tool was designed to systematically analyze all 20,000 human protein-coding genes. It specifically searched for the characteristic sites where prohormone convertases, like PC1/3, typically cleave proteins.

The algorithm further refined the search by prioritizing genes that produce proteins secreted outside the cell – a common trait of hormones – and that contained at least four potential cleavage sites. This intelligent filtering process dramatically reduced the pool of potential candidates from the entire human genome to a more manageable group of 373 prohormones, making the subsequent experimental investigation feasible. "The algorithm was absolutely key to our findings," Svensson reiterated, underscoring its pivotal role in the discovery.

Peptide Predictor estimated that PC1/3 could generate an impressive 2,683 distinct peptides from these 373 prohormones. Coassolo and Svensson then narrowed their focus to peptide sequences that showed the highest likelihood of impacting brain function. They selected approximately 100 peptides, including GLP-1, for experimental validation.

A Tiny Peptide with an Outsized Effect

The initial validation involved testing these selected peptides for their ability to stimulate neuron-like cells cultured in the laboratory. As anticipated, GLP-1 demonstrated a strong stimulatory effect, increasing neuronal activity by threefold compared to untreated control cells. However, it was a much smaller peptide that produced an even more remarkable response. This peptide, BRP, composed of a mere 12 amino acids, boosted neuronal activity by a staggering tenfold compared to controls.

The researchers named this potent peptide BRP, derived from its parent prohormone, BPM/retinoic acid inducible neural specific 2 (BRINP2). Amino acids are the fundamental building blocks of proteins and peptides. A molecule comprising only 12 amino acids is exceptionally small, especially when contrasted with the larger structures of most full-length proteins. Yet, BRP’s diminutive size belied its extraordinary impact in these initial cell-based assays.

Preclinical Efficacy: Significant Weight Loss and Improved Metabolic Markers

Following the promising in vitro results, the research team advanced their studies to in vivo models. They tested BRP in both lean mice and, importantly, minipigs. Minipigs were chosen for their physiological similarities to humans in terms of metabolism and eating patterns, making them a more relevant model than mice for certain aspects of this research.

In these animal studies, an intramuscular injection of BRP administered prior to feeding led to a significant reduction in food intake, with intake falling by up to 50% in the hour following administration in both species. This demonstrated BRP’s potent appetite-suppressing capabilities in a more complex biological system.

The researchers further investigated BRP’s effects on weight management by administering daily injections to obese mice over a 14-day period. The results were compelling: treated animals experienced an average weight loss of 3 grams, with nearly all of this reduction attributed to body fat. In contrast, the control group of obese mice gained approximately 3 grams during the same timeframe, highlighting BRP’s effectiveness in promoting fat loss.

Beyond weight reduction, the BRP-treated mice also exhibited improvements in glucose and insulin tolerance. These metrics are critical indicators of metabolic health, reflecting the body’s efficiency in regulating blood sugar levels and its response to insulin, a hormone essential for transporting glucose from the bloodstream into cells for energy. Improved glucose and insulin tolerance suggest that BRP may offer broader metabolic benefits beyond just appetite suppression.

Promising Safety Profile: Absence of Common Side Effects

One of the most encouraging aspects of the BRP research is its apparent lack of common side effects associated with existing weight-loss medications, particularly semaglutide. Behavioral assessments in the animal models revealed no significant differences between BRP-treated and untreated animals in parameters such as movement, water consumption, anxiety-like behavior, or fecal production.

The absence of changes in fecal production is particularly noteworthy. Semaglutide is known to slow down digestion, which can lead to constipation in some individuals. The fact that BRP did not appear to cause this gastrointestinal disturbance suggests a potentially gentler impact on the digestive system. Furthermore, the researchers did not observe any signs of nausea-related responses or substantial muscle loss, which have been reported with certain other weight-loss treatments. These observations strongly indicate that BRP may offer a more tolerable therapeutic profile.

Additional analyses of brain activity and overall body function confirmed that BRP engages metabolic and neuronal pathways that are distinct from those activated by GLP-1 or semaglutide. This divergence in mechanism further supports the notion that BRP could offer a more targeted and potentially safer approach to managing appetite and body weight.

Navigating the Path to Human Trials

Despite the encouraging preclinical data, the researchers acknowledge that significant work remains before BRP can be considered for widespread human use. A primary focus of ongoing research is to precisely identify the cell-surface receptors to which BRP binds. Receptors are the molecular docking stations that receive signals from hormones, drugs, and other chemical messengers, dictating how a substance exerts its effects. Understanding BRP’s specific receptor interaction is crucial for a comprehensive understanding of how it influences appetite and metabolism.

The team also aims to map the complete cascade of events that occur after BRP binds to its target receptor. This detailed understanding of the signaling pathway will provide further insights into its mechanism of action and potential downstream effects.

Another significant challenge is the duration of BRP’s action. Small peptides, by their nature, can be rapidly broken down by enzymes in the body, potentially limiting their therapeutic window. The researchers are actively exploring strategies to enhance the stability and longevity of BRP, aiming to develop formulations that can be administered on a more practical and convenient schedule for patients.

"The lack of effective drugs to treat obesity in humans has been a problem for decades," Svensson remarked. "Nothing we’ve tested before has compared to semaglutide’s ability to decrease appetite and body weight. We are very eager to learn if it is safe and effective in humans." This sentiment reflects the high hopes and cautious optimism surrounding BRP’s potential to address a major unmet medical need.

The collaborative effort behind this research involved contributions from researchers at the University of California, Berkeley; the University of Minnesota; and the University of British Columbia, highlighting a broad base of scientific expertise dedicated to this promising discovery. Funding for the study was provided by a consortium of prestigious institutions, including the National Institutes of Health, the SPARK Translational Research Program at Stanford, Stanford Bio-X, the Stanford Maternal and Child Health Research Institute, the American Heart Association, a Stanford Medicine Dean’s Fellowship Award, the Carlsberg Foundation, and the Wu Tsai Human Performance Alliance.

Svensson and Coassolo are listed as inventors on patents related to BRP peptides for metabolic disorders, further underscoring their foundational role in this area of research. Svensson is also a co-founder of Merrifield Therapeutics, a company poised to advance BRP into human clinical trials, signaling a direct path from laboratory discovery to potential clinical application. The journey of BRP from a computationally predicted peptide to a potential therapeutic agent represents a significant leap forward in the ongoing quest for more effective and safer weight management solutions.