Once considered the “Holy Grail” of weight loss, Belviq may have exposed millions of users to an increased risk of cancer.
Belviq (locaserin) is indicated for use in combination with diet to aid weight loss in obese adults who suffer from weight-related health problems. The drug works by activating the brain’s serotonin receptors, which produces feelings of fullness and satisfaction.
The U.S. Food & Drug Administration (FDA) approved Belviq in 2012, following a two-year delay precipitated by animal studies that suggested locaserin might increase the risk for cancer. However, the agency was eventually convinced that the tumors seen in those studies were specific to the animals.
The FDA was also concerned that Belviq might cause heart valve problems, a side effect that had previously resulted in the recall of another weight loss drug called fenfluramine. However, the manufacturer was able to provide data indicating this complication would not occur with the low doses at which Belviq would be prescribed, clearing the way for the drug’s launch.
The agency allowed sales of Belviq XR – an extended version of locaserin — in 2016.
The FDA’s approval of Belviq was not without condition, as the agency required a post-market study to better assess locaserin’s possible association with heart attack, stroke, and other serious heart problems. That study, which involved over 12,000 obese and overweight people treated with either Belviq or a placebo, was completed in 2018 and showed that locaserin was an effective tool for weight loss and safe for the heart.
“I think it is the thing everybody has been looking for,” Tam Fry, of Britain’s National Obesity Forum, told The Guardian at the time.
“I think there will be several holy grails, but this is a holy grail and one which has been certainly at the back of the mind of a lot of specialists for a long time.”
Unfortunately, the initial optimism surrounding Belviq appears to have been premature.
Last month, the FDA announced that further review of the post-market study suggested cancer occurred more frequently among subjects taking Belviq compared to those taking a placebo. On February 13th, the agency asked the drug’s manufacturer to remove Belviq and Belviq XR from the market.
According to the FDA’s most recent Drug Safety Communication, 7.7% of trial participants who took Belviq were diagnosed with cancer, compared to just 7.1% in the placebo group. That amounted to one additional cancer for every 470 patients treated with Belviq for one year.
While a range of cancers were seen during the course of the study, pancreatic, colorectal. and lung cancers were reported more often in the patients who took Belviq.
Esai, Inc. has agreed to conduct a Belviq recall. In the meantime, individuals who use Belviq or Belviq XR have been advised to stop taking the medication and speak with their doctors about alternative treatments. The agency has also asked healthcare providers not to prescribe locaserin products and to inform current Belviq patients of the cancer risk.