Lexicon Pharmaceuticals, Inc. (Nasdaq: LXRX) announced today that top-line data from its TELECAST Phase 3 study showed results of telotristat etiprate in treating carcinoid syndrome in cancer patients with metastatic neuroendocrine tumors consistent with the clinical benefit observed in its pivotal TELESTAR study. The TELECAST study was designed as a companion to TELESTAR primarily to provide additional safety exposure while further evaluating telotristat etiprate's activity in carcinoid syndrome. TELECAST mostly enrolled patients treated with somatostatin analog (SSA) therapy, the current standard of care, with carcinoid syndrome characterized by less severe bowel movement frequency than those patients in the TELESTAR study, together with a smaller number of carcinoid syndrome patients not treated with SSA therapy.
Telotristat etiprate met the study's primary efficacy endpoint, the percent change from baseline in urinary 5-hydroxyindoleacetic acid (5-HIAA, the main metabolite of serotonin) at week 12, the final week of the double-blind treatment portion of the study (p<0.001 for both dose arms compared to placebo). In addition, despite the lower baseline bowel movement frequency than in TELESTAR, telotristat etiprate achieved statistically significant reductions in daily bowel movement frequency over the 12 weeks of the study (p=0.004 for the 250 mg dose arm and p<0.001 for the 500 mg dose arm compared to placebo). Safety and tolerability was one of the primary objectives of the TELECAST study, and telotristat etiprate was well tolerated during the double-blind treatment period, with profiles similar to placebo for both the 250 mg and 500 mg dose arms and no overall differences observed in gastrointestinal disorders or psychiatric disorders, including changes in mood.
"We are very pleased with the efficacy and safety results of telotristat etiprate in this study, notably including evidence of benefit in a patient population whose bowel movement frequency was lower at baseline than was the case in TELESTAR," said Lexicon Executive Vice President and Chief Medical Officer Pablo Lapuerta, M.D. "TELECAST was intended to complement our pivotal Phase 3 trial, TELESTAR. We now have experience in more than 200 patients with carcinoid syndrome, with TELECAST contributing consistent efficacy data and favorable safety results. The data further support that the compound is acting directly on the cause of carcinoid syndrome, by reducing serotonin production within tumor cells."
Carcinoid syndrome is a rare disease affecting thousands of cancer patients with metastatic neuroendocrine tumors (mNETs) that have spread to the liver and other organs from the gastrointestinal tract. The condition is characterized by frequent and debilitating diarrhea that often prevents patients from leading active, predictable lives, as well as by facial flushing, abdominal pain, fatigue and, over time, heart valve damage.
Results from Lexicon's pivotal TELESTAR Phase 3 study were presented earlier this year at the European Cancer Conference and the annual symposium of the North American Neuroendocrine Tumor Society.
TELECAST Results
The double-blind TELECAST study enrolled 76 patients with or without concomitant SSA therapy provided they qualified based on at least one sign/symptom of carcinoid syndrome, such as at least two episodes of flushing per day, elevated urinary 5-HIAA at baseline, or nausea present on at least one out of five days at baseline. Patients who were not receiving SSA therapy could also qualify for the study based on experiencing at least four bowel movements per day as their sign/symptom. The three-arm study evaluated two doses of oral telotristat etiprate – 250 mg and 500 mg, each taken three times daily – against placebo over a 12-week period with primary outcome measures consisting of safety and the percent change from baseline in urinary 5-HIAA, and secondary outcome measures including change from baseline in the number of daily bowel movements. Patients in both the treatment and placebo arms who were on SSA therapy at baseline continued their SSA therapy throughout the study.
Data showed that patients treated with telotristat etiprate at both the 250 mg and 500 mg doses experienced a statistically significant percent reduction from baseline compared to placebo in urinary 5-HIAA, the main metabolite of serotonin, at week 12, the final week of the double-blind treatment portion of the study (p<0.001), meeting the study's primary efficacy endpoint.
In addition, data showed that patients treated with telotristat etiprate at both the 250 mg and 500 mg doses experienced a statistically significant percent reduction from baseline compared to placebo in the average number of daily bowel movements over the 12 weeks of the study (p=0.004 for the 250 mg dose arm and p<0.001 for the 500 mg dose arm compared to placebo).
Treatment with telotristat etiprate was well tolerated during the double-blind treatment period. The proportions of patients with treatment-emergent adverse events (AEs) were 100% in the 250 mg arm, 84% in the 500 mg arm and 81% in the placebo group during the 12-week study period. The proportions of patients with serious AEs (none of which were deemed related to treatment) were 4% in the 250 mg arm, 8% in the 500 mg arm and 19% in the placebo group. The proportions of patients who discontinued treatment due to AEs were 8% in the 250 mg arm, 0% in the 500 mg arm and 4% in the placebo group. Notably, in terms of pre-defined AEs of special interest, both doses of telotristat etiprate appeared similar to placebo, with three patients experiencing nausea in the 250 mg arm, two in the 500 mg arm and four in the placebo group, and one patient experiencing depression or depressed mood in each of the 250 mg and 500 mg arms and two in the placebo group.
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