GATTEX SIDE EFFECTS

SIDE EFFECTS

The following serious adverse reactions are described elsewhere in the labeling:

• Acceleration of Neoplastic Growth
• Intestinal Obstruction
• Biliary and Pancreatic Disease
• Fluid Imbalance and Fluid Overload

Clinical Trials Experience

Adults

Because clinical trials are conducted under widely varying conditions, the adverse reaction rates observed cannot be directly compared to rates in other clinical trials and may not reflect the rates observed in clinical practice.

The rates of adverse reactions in 136 adult patients with SBS participating in two randomized, placebo-controlled, 24-week, double-blind clinical studies (Study 1 and Study 3) are summarized in Table 1. Only those reactions with a rate of at least 5% in the GATTEX group, and greater than placebo group, are summarized in Table 1.

Table 1: Common Adverse Reactions* in Adult Patients with SBS in Placebo-Controlled Studies: Studies 1 and 3

Adverse Reactions In The Subset Of Patients With A Stoma

Among the 53 patients with a stoma in the placebo-controlled studies (Study 1 and Study 3), the percentage of patients with gastrointestinal stoma complication was 42% (13/31) for patients receiving GATTEX 0.05 mg/kg/day and 14% (3/22) for patients receiving placebo.

Pediatric Patients 1 Year To Less Than 17 Years Of Age

In two clinical studies of 24-week and 12-week duration, 41 pediatric patients aged 1 year to less than 17 years were treated with GATTEX 0.05 mg/kg/day. Overall, the safety profile of GATTEX was similar to that in adults. In the long-term extension studies with mean exposure of 41 weeks, no new safety signals were identified.

Less Common Adverse Reactions

Adverse Reactions Of Special Interest

Malignancy

Three patients were diagnosed with malignancy in the SBS clinical studies in adults, all of whom were male and had received GATTEX 0.05 mg/kg/day in Study 2. One patient had a history of abdominal radiation for Hodgkin’s disease two decades prior to receiving GATTEX and prior liver lesion on CT scan, and was diagnosed with metastatic adenocarcinoma of unconfirmed origin after 11 months of exposure to GATTEX. Two patients had extensive smoking histories and were diagnosed with lung cancers (squamous and non-small cell) after 12 months and 3 months of GATTEX exposure, respectively.

Intestinal Polyps

In the adult clinical studies, 14 patients with SBS were diagnosed with polyps of the GI tract after initiation of study treatment. In the SBS placebo-controlled studies, 1/59 (2%) of patients on placebo and 1/109 (1%) of patients on GATTEX 0.05 mg/kg/day were diagnosed with intestinal polyps (inflammatory stomal and hyperplastic sigmoidal after 3 and 5 months, respectively). The remaining 12 polyp cases occurred in the extension studies – 2 colorectal villous adenomas (onset at 6 and 7 months in GATTEX 0.1 mg/kg/day (twice the recommended dose) and 0.05 mg/kg/day dose groups, respectively), 2 hyperplastic polyps (onset 6 months in GATTEX 0.1 mg/kg/day dose group and 24 months in GATTEX 0.05 mg/kg/day dose group), 4 colorectal tubular adenomas (onset between 24 and 29 months in GATTEX 0.05 mg/kg/day dose group), 1 serrated adenoma (onset at 24 months in GATTEX 0.05 mg/kg/day dose group), 1 colorectal polyp biopsy not done (onset at 24 months in GATTEX 0.05 mg/kg/day dose group), 1 rectal inflammatory polyp (onset at 10 months in the GATTEX 0.05 mg/kg/day dose group, and 1 small duodenal polyp (onset at 3 months in GATTEX 0.05 mg/kg/day dose group).

In the pediatric clinical studies (up to 69 weeks of exposure), there was one case of cecal polyp that was not biopsied and was not seen on repeat colonoscopy.

Gastrointestinal Obstruction

Overall, in the adult clinical studies, 12 patients with SBS experienced one or more episodes of intestinal obstruction/stenosis: 6 in SBS placebo-controlled studies and 6 in the extension studies. The 6 patients in the placebo-controlled studies were all on GATTEX: 3/77 (4%) on GATTEX 0.05 mg/kg/day and 3/32 (9%) on GATTEX 0.1 mg/kg/day (twice the recommended dose). No cases of intestinal obstruction occurred in the placebo group. Onset ranged from 1 day to 6 months. In the adult extension studies, 6 additional patients (all on GATTEX 0.05 mg/kg/day) were diagnosed with intestinal obstruction/stenosis with onsets ranging from 6 days to 19 months. Two of the 6 patients from the placebo-controlled studies experienced recurrence of obstruction in the extension studies. Of all 8 patients with an episode of intestinal obstruction/stenosis in these extension studies, 2 patients required endoscopic dilation and 1 required surgical intervention).

In the pediatric clinical studies (up to 69 weeks of exposure), there was 1 serious adverse reaction of obstruction. Teduglutide was temporarily withheld, obstruction resolved without additional intervention, and there was no recurrence once teduglutide was restarted.

Gallbladder, Biliary And Pancreatic Disease

For gallbladder and biliary disease in the adult placebo-controlled studies, 3 patients with SBS were diagnosed with cholecystitis, all of whom had a prior history of gallbladder disease and were in the GATTEX 0.05 mg/kg/day dose group. No cases were reported in the placebo group. One of these 3 cases had gallbladder perforation and underwent cholecystectomy the next day. The remaining 2 cases underwent elective cholecystectomy at a later date. In the adult extension studies, 4 patients had an episode of acute cholecystitis; 3 patients had new-onset cholelithiasis; and 1 patient experienced cholestasis secondary to an obstructed biliary stent. For pancreatic disease in the adult placebo-controlled studies, 1 patient (GATTEX 0.05 mg/kg/day dose group) had a pancreatic pseudocyst diagnosed after 4 months of GATTEX. In the adult extension studies, 1 patient was diagnosed with chronic pancreatitis; and 1 patient was diagnosed with acute pancreatitis.

Fluid Overload

In the adult placebo-controlled studies, peripheral edema was reported in 2/59 (3%) of patients on placebo and 8/77 (10%) patients on GATTEX; fluid overload was reported in 1/77 (1%) patient in the GATTEX group; no cases of fluid overload were seen in the placebo arm. There were 2 cases of congestive heart failure (CHF, 3%) in the GATTEX arm, 1 of which was reported as a serious adverse event and the other as non-serious. The serious case had onset at 6 months and was possibly associated with previously undiagnosed hypothyroidism and/or cardiac dysfunction.

Other Less Common Adverse Reactions

Reported in less than 5% of patients treated with GATTEX:

Gastrointestinal disorders: Colonic stenosis, Pancreatic duct stenosis, Small intestinal stenosis

Respiratory, thoracic and mediastinal disorders: Dyspnea

Immunogenicity

As with all peptides, there is potential for immunogenicity. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to teduglutide in the studies described below with the incidence of antibodies in other studies or to other products may be misleading.

Adults

Based on integrated data from two studies in adults with SBS (a 6-month randomized placebo-controlled study, followed by a 24-month open-label study), the development of anti-teduglutide antibodies in patients who received subcutaneous administration of 0.05 mg/kg GATTEX once daily was 3% (2/60) at Month 3, 17% (13/77) at Month 6, 24% (16/67) at Month 12, 33% (11/33) at Month 24, and 48% (14/29) at Month 30. Anti-teduglutide antibodies were cross-reactive to native glucagon-like peptide (GLP-2) in 5 of the 6 patients (83%) who had anti-teduglutide antibodies and were tested for cross-reactivity. In the same two studies, a total of 36 patients were tested for neutralizing antibodies: one patient developed borderline positive neutralizing antibody responses at month 24 of the extension study. The antibody formation has not been associated with clinically relevant safety findings, reduced efficacy or changed pharmacokinetics of GATTEX.

Pediatric Patients 1 Year To Less Than 17 Years Of Age

In pediatric patients who received subcutaneous administration of 0.05 mg/kg GATTEX once daily for 24 weeks, the rate of anti-teduglutide antibody formation at Month 6 was 19% (5/26) and was similar to the rate of antibody formation in adult patients (17%). Of the 5 pediatric patients who had developed antibodies to teduglutide at Month 6, 2 patients had neutralizing antibodies. However, with the longer duration of treatment, the rate of anti-teduglutide formation at Month 12 was higher in pediatric patients with 54% (14/26), compared to that of adults (24%). Of the 14 pediatric patients who had developed antibodies to teduglutide at Month 12, 1 patient had neutralizing antibodies.

Among the small number of pediatric patients who developed anti-teduglutide antibodies, no association with adverse events or lack of efficacy was observed.

SRC: NLM .