Patterns and Predictors of Weight Loss with Exenatide Treatment in Overweight and Obese Women

In the medical management of obesity, treating physicians observe significant heterogeneity in responses to pharmacotherapy. Indeed one of the most important clinical questions in obesity medicine is whether we can predict how an individual will respond to a particular pharmacotherapeutic agent. The present study examines patterns and predictors of weight loss among overweight and obese women who demonstrated early robust response to twice daily exenatide treatment. 182 women were assigned using single-blind randomization to either treatment with twice daily exenatide injections or to matched placebo injections with dietary counseling. Women who demonstrated > 5% weight loss after 12 weeks of treatment were deemed high responders and remained on study treatment for up to 52 weeks; women who lost < 5% body weight at 12 weeks were deemed low responders and stopped study treatment. We additionally characterized individuals who lost > 10% of body weight as super responders. Our primary outcome was change in body weight; secondary outcomes included changes in metabolic parameters including lipids, waist circumference, resting energy expenditure, and response to a meal tolerance test. We also performed an exploratory metabolomic analysis. Consistent with published literature, we observed individual heterogeneity in the weight loss response to exenatide and diet/placebo. Although there was no significant difference between treatment groups in the percentage of participants who achieved > 5% weight loss (56% of exenatide group and 76% of diet/placebo group), or those who achieved > 10% weight loss (43% of exenatide group and 55% of diet/placebo group), in both cases there was a trend toward a higher response rate in the group that received placebo with dietary counseling. In addition to achieving similar average weight loss, both treatment groups also demonstrated similar maximum weight loss. The range of maximum weight loss was greater in the diet/placebo group and there was more weight regain among individuals in the exenatide group compared to the diet/placebo group. In our exploratory metabolomic analysis, we observed lower baseline circulating cysteine concentrations in the exenatide responder group and we also found a trend toward higher baseline levels of serotonin, aminoisobutyric acid, anandamide, and sarcosine in the exenatide super responder group. We did not identify any metabolic predictors of weight loss in either the exenatide or the diet/placebo treatment group.