The FDA has approved Xermelo (telotristat ethyl, Lexicon Pharmaceuticals) tablets in combination with somatostatin analog (SSA) therapy for the treatment of adults with carcinoid syndrome diarrhea that SSA therapy alone has inadequately controlled.
Carcinoid syndrome is a cluster of symptoms sometimes seen in people with carcinoid tumors. These tumors are rare and often slow-growing. Most carcinoid tumors are found in the gastrointestinal tract. Carcinoid syndrome occurs in less than 10% of patients with carcinoid tumors, usually after the tumor has spread to the liver. The tumors in these patients release excess amounts of the hormone serotonin, resulting in diarrhea. Complications of uncontrolled diarrhea include weight loss, malnutrition, dehydration, and electrolyte imbalance.
Xermelo, in a regimen with SSA therapy, is approved in tablet form to be taken orally three times daily with food. Xermelo inhibits the production of serotonin by carcinoid tumors and reduces the frequency of carcinoid syndrome diarrhea.
The safety and efficacy of the drug were established in a 12-week, double-blind, placebo-controlled trial in 90 adult patients with well-differentiated metastatic neuroendocrine tumors and carcinoid syndrome diarrhea. These patients were having between four to 12 daily bowel movements despite the use of SSA at a stable dose for at least three months. Participants remained on their SSA treatment and were randomized to add placebo or treatment with Xermelo three times daily. Those receiving Xermelo added to their SSA treatment experienced a greater reduction in average bowel movement frequency than those on SSA and placebo. Specifically, 33% of participants randomized to the addition of Xermelo to SSA experienced an average reduction of two bowel movements per day compared to 4% of patients randomized to add placebo to SSA.
The most common side effects of Xermelo include nausea, headache, increased levels of the liver enzyme gamma-glutamyl transferase, depression, accumulation of fluid causing swelling (peripheral edema), flatulence, decreased appetite, and fever. Xermelo may cause constipation, and the risk of developing constipation may be increased in patients whose bowel movement frequency is less than four bowel movements per day. Patients treated with a higher than recommended dosage of Xermelo developed severe constipation in clinical trials. One patient required hospitalization and two other patients developed complications of either intestinal perforation or intestinal obstruction. Patients should be monitored for severe constipation. If a patient experiences severe constipation or severe, persistent or worsening abdominal pain, they should discontinue Xermelo and contact their health care provider.
The FDA granted this application fast-track designation and priority review. The drug also received orphan drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.
Source: FDA; February 28, 2017.