A One-year Randomized Trial of Lorcaserin for Weight Loss in Obese and Overweight Adults: The BLOSSOM Trial

Introduction:  Lorcaserin, a novel selective serotonin 2C (5-HT2C) receptor agonist, is in clinical development for weight loss.  The BLOSSOM study was done to assess the efficacy and safety of lorcaserin dose ranges when the drug is administered with lifestyle modifications (nutritional and physical activity programs).

Methods:  The study was a randomized, placebo-controlled, double-blind, parallel arm trial.  Ninety-seven research centers were involved in the United States.  There were 4,008 patients (ages 18-65 years), and they had a body mass index (BMI) of 30-45 kg/m2, or they had an obesity-related comorbidity and a BMI of 27-29.9 kg/m2.

Randomization was in a 2:1:2 ratio into the following groups:

No matter which group they were in, patients received nutrition and physical activity advice.

Primary endpoints at 1-year were:

Heart valve function was monitored using serial echocardiograms.

Results:  Compared with placebo, significantly more patients in the 10 mg BID and the 10 mg QD groups lost at least 5% of their body weight (47.2% and 40.2%, respectively; placebo was 25.0%; p < 0.001 when compared to 10 mg BID).

For 10 mg BID, least squares mean weight loss was 5.8% (5.5-6.2%; 95% confidence interval); for 10 mg QD, it was 4.7% (4.3-5.2%; 95% confidence interval). In the placebo group, least squares mean weight loss was 2.8% (2.5-3.2%; p < 0.001 when compared to 10 mg BID).

In the 10 mg BID group, 22.6% achieved at least 10% weight loss; 27.4% of the 10 mg QD group achieved this.  The placebo group had 9.7% losing at least 10% of body weight (p < 0.001 when compared to 10 mg BID).

The most common adverse events in the lorcaserin groups were headache, nausea, and dizziness.

Echocardiographic valvulopathy (as defined by the US FDA) occurred in 2.0% of patients in the placebo group; 2.0% of patients in the 10 mg BID group also developed echocardiographic valvulopathy.

Conclusions:  When combined with lifestyle modifications, lorcaserin showed a dose-dependent weight loss effect that was significantly greater than placebo.

Commentary by J. Michael Gonzalez-Campoy MD, PhD, FACE

Read Dr. Gonzalez-Campoy's commentary on this study in his introduction.