Redefining Clinical Development of Obesity Drugs: What Does Success Look Like? 

Nearly seven years after the FDA approved Novo Nordisk’s Ozempic for diabetes treatment, this medication and other GLP-1 receptor agonists have proven very effective in promoting weight loss. For the millions struggling with obesity, they offer a way to reduce appetite, manage blood sugar levels, lose weight, and decrease the risk of the comorbidities associated with having a higher body mass.

The World Obesity Federation has warned that by 2035 approximately 4.4 billion people globally will be classified as obese. This would lead to a predicted $4.32 trillion burden on global economies and consequences for healthcare systems comparable to the impact of Covid-19 in 2020. 

Studies have shown that GLP-1 drugs can help individuals achieve an average weight loss of 15% of their total body weight. In terms of immediacy and relative ease, this far outperforms the rate of weight loss that can be achieved with lifestyle interventions and approaches the results from surgical treatments. 

Despite promising outcomes, the question remains: do medications like Novo Nordisk’s Wegovy, Eli Lilly’s Mounjaro, Ozempic, and the 120 other treatments currently in development provide a sustainable, long-term solution for obesity? Weight loss alone does not guarantee improved health outcomes, especially for the long-term. On the contrary, reduced weight loss can be detrimental to health if a significant portion of that lost weight is accounted for by muscle mass. Furthermore, when patients discontinue the medication, they could regain weight, mainly in the form of fat. These concerns were raised in multiple studies, such as the STEP 1 and STEP 4 trials, which reported significant weight regain after discontinuation of the semaglutide treatment. This could become a vicious cycle leading to sarcopenia, frailty and long-term health issues.

Both medical professionals and the media are increasingly educating patients about the potential downsides of these medications, emphasizing that they are not a ‘solve-all’ solution. As multi-billion investment continues to pour into the R&D of future obesity medications, the need for evidence generation of health benefits beyond short-term weight loss will be critical to the decision-making of healthcare providers and payers. It is time to set a new standard for evidence generation in obesity clinical trials. Next, we discuss why objective assessments of physical activity should be an integral component of obesity trials. 

Physical activity, a key aspect of lifestyle intervention, is commonly included in clinical trials in obesity. For example, in the STEP 4 clinical trial of semaglutide, participants in both the treatment and placebo groups were instructed to increase their physical activity by 150 minutes weekly. As such, approved GLP-1 medications are labelled as adjunct treatments to a lifestyle intervention including increased physical activity. 

More importantly, increased physical activity or exercise is critical to long-term health benefit. The University of Copenhagen led a comprehensive study to examine the interactions between GLP-1 medication and physical activity using a multi-armed randomised control trial.  They demonstrated that the combination of GLP-1 medication and physical activity produced more sustainable impact on obesity management than the use of GLP-1 medication alone.  

Therefore, the adherence to a physical activity intervention among participants likely has a substantial impact on the efficacy of the treatment, especially on muscle preservation and long-term maintenance. Drug developers will need to supply more robust data to reassure payers and healthcare professionals of the long-term sustainability of medication-aided weight loss. This will be what distinguishes the most effective treatments as the industry advances obesity care. Accounting for this variable in a clinical trial can reduce statistical noise in the data, which is critical to obtaining a more comprehensive and nuanced picture of the treatment effect. 

So far, physical activity has been self-reported via paper diaries or apps, and no objective data collected to quantify participants’ physical activity levels. While traditional self-reported methods provide some insights, they are subjective and susceptible to recall bias. On the other hand, wearable technology has been widely used by academic researchers and consumers to objectively track physical activity, such as step count, speed, and duration, delivering a more accurate view than self-reported data. Wearables can also provide objective measures of sleep, which is negatively impacted by obesity and at the same time could interfere with obesity intervention. Incorporating these objective digital measures into clinical trials will give a clearer picture of how pharmacotherapy and lifestyle factors influence a patient’s weight loss, muscle mass, and long-term maintenance, and better support drug developers with more precise and robust evidence on the efficacy of their novel therapies. 

Beyond the use of wearable technology to track lifestyle factors during intervention, it also provides novel outcome assessments as meaningful clinical endpoints needed for regulatory approval and payer reimbursements. Wearable technology can objectively assess the quality of physical activity and level of physical fitness. It is well established in the literature that speed and amount of walking improve with muscle strength, physical capacity, and cardiovascular fitness, and can predict long-term health outcomes. With wearable technology, we can now assess walking speed and bouts in the real world with minimal patient burden. In addition to quantifying activity, newer technology such as optical photoplethysmogram (PPG) on wearables has the potential to estimate VO₂Max and sleep apnea.  These real-world insights can reveal how obesity treatments impact daily functioning and quality of life.  Not only do wearable-derived digital measures provide more meaningful clinical endpoints than weight loss for clinical trials, but they can also inform personalized and effective treatment plans​​ in the real world.

There is a need to set standards against the levels of physical activity required to maximize the efficacy of GLP-1 medications. Incorporating wearable DHTs into obesity trials and routine care can help develop evidence-based guidelines. By understanding the optimal types and amounts of physical activity that support muscle preservation and weight maintenance and incorporating these into clinical research, healthcare providers can offer more targeted and practical recommendations to patients, which may help them to shift the pounds for the long term.

Photo: Peter Dazeley, Getty Images

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