SILVER SPRING, MD. – A Food and Drug Administration advisory panel unanimously supported the approval of teduglutide, a recombinant analogue of human glucagon-like peptide-2 (GLP-2), as a treatment to improve the intestinal absorption of fluid and nutrients in adults with short bowel syndrome, with recommendations to follow the drug’s long-term safety, at a meeting on Oct. 16.
At a meeting in September, the FDA’s Gastrointestinal Drugs Advisory Committee voted 12 to 0 that the benefits of teduglutide outweighed the potential risks in patients with short bowel syndrome (SBS). In phase III studies of 169 adults with SBS, whose estimated small bowel length was a mean of 72 cm and who had been on parenteral nutrition and IV therapy for a mean of 7 years, teduglutide significantly reduced the volume of parenteral nutrition and IV fluids they needed after 6 months of treatment, compared with placebo.
While the panelists unanimously agreed that the results represented a clinically meaningful benefit for these patients and generally felt comfortable with the drug’s safety profile, they recommended that more safety data are needed, including determining whether the risk of colorectal cancer is increased with treatment.
Produced in the distal small intestine and proximal large intestine, GLP-2 is "an intestinotrophic peptide that stimulates mucosal epithelium," increasing absorption of fluids and nutrients, according to the manufacturer, NPS Pharmaceuticals. In studies, patients treated with teduglutide, administered subcutaneously once a week, had evidence of increased villus height after 21 days of treatment, according to the company.
In the main phase III study of 86 adults with SBS, 63% of those treated with 0.05 mg/kg daily had at least a 20% reduction in the volume of parenteral nutrition and IV fluids (the primary end point) required after 24 weeks of treatment, compared with 30% of those on placebo; this was a statistically significant difference. The volume of parenteral nutrition and IV fluids from baseline to the 24th week of treatment was reduced by a median of 4.4 L/week among patients on teduglutide, compared with 2.3 L/week for patients on placebo. Teduglutide treatment also led to a higher percentage of patients with at least one day less on therapy than did placebo (54% vs. 23%). An extension study indicated that this effect was maintained through 1 year of treatment.
While the FDA reviewers agreed that the drug had clinically meaningful effects in the studies, they raised some safety issues, mainly potential tumor-promoting effects, as well as potential GI side effects that included biliary and pancreatic disease and GI stenosis and obstruction. To date, there have been no reports of small bowel malignancies in treated patients; the three malignancies reported in treated patients have been a metastatic adenocarcinoma in a patient who had been on treatment for almost a year and lung cancer in two patients who had a history of smoking. Adenomas were seen in the bile duct and jejunum of rats at 700 times the human dose, findings that are "consistent with the pharmacological effects of the drug," according to the FDA.
There was also a low incidence of intestinal obstruction and stenosis, cholecystitis, and pancreatic disease in treated patients, compared with no cases among those on placebo.
NPS has proposed a registry of treated patients to evaluate the long-term safety and effectiveness of teduglutide, and a risk evaluation and mitigation strategy (REMS) aimed at educating prescribers about the potential and known risks of treatment. The REMS would include a letter to health care professionals and professional societies, including the American Gastroenterological Association and the American College of Gastroenterology; and drug labeling that includes contraindications in patients with a history of malignancy or with active or currently suspected malignancy, as well as warnings and precautions about the possible acceleration of neoplastic growth, colorectal polyps, and small bowel neoplasia.
The panel voted 10 to 1, with one abstention, that the company’s plans were adequate for addressing the safety concerns, although they pointed out that the number of patients in the studies was small and recommended close follow-up of treated patients.
"It seems like it’s a fairly safe drug," but follow-up is short term and fewer than 200 patients have been treated with teduglutide, said panelist Dr. Kevin Kelly, director of the division of solid tumor oncology at Thomas Jefferson University, Philadelphia. He and others recommended that patients be followed for up to 10 years.
"My gut feeling is that this is probably a very safe drug" that does not increase the risk of carcinogenesis, said another panelist, Dr. Ronald Fogel of the Digestive Health Center of Michigan in Chesterfield. He recommended more aggressive follow-up of treated patients than was proposed by the company, which he said could include serial colonoscopies at 2-year intervals with multiple biopsies at areas of dysplasia.
