Octreotide Therapy in Children and Young Adults With Prader-Willi Syndrome (PWS)

Investigation of the Developmental, Nutritional and Hormonal Regulation of Ghrelin in Children and Young Adults With Prader-Willi Syndrome (PWS): Octreotide Intervention Sub-study

The purpose of this study is to investigate over a 6 month period the effect of octreotide therapy on food intake, sense of hunger, body weight, body composition, efficiency of burning calories, biomarkers of weight regulation and growth hormone markers in children and young Adults with Prader-Willi Syndrome(PWS).

Obesity continues to be a prevalent health concern affecting every race of the American population. According to data from the World Health Organization, 54% of U.S. adults are overweight (body mass index (BMI) >25 kg/m2 ) and 22% are obese (BMI >30 kg/m2) (1). In addition, 25% of U.S. children are overweight or obese (1). Studies show that obese children are likely to become obese adults (2-5). Also, recent studies report significant years of life lost due to the impact of being an obese adult (6, 7). Thus, insights into the pathogenesis of childhood obesity and preventative measures are needed to combat the inevitable increase in worldwide incidence of obesity and its associated co-morbidities. Recent studies have identified a new gastroenteric hormone, ghrelin, as a long-term regulator of energy balance in humans (12). Ghrelin is a 28 amino acid acylated peptide which is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), a hypothalamic G-protein-coupled receptor (13). Enteroendocrine cells (X/A-like cells) of the stomach are the major site of ghrelin synthesis, although a minor proportion of ghrelin synthesis occurs in other sites such as the hypothalamus, pituitary, duodenum, jejunum and lung (14) (15, 16).

The hypothesis that hyperghrelinemia causes some of the features of PWS predicts that this disorder will be ameliorated (partially or completely) by lowering ghrelin levels. We have recently shown that the somatostatin agonist, octreotide, suppresses ghrelin levels in humans. If octreotide remains effective in longer term studies, the drug may become an adjuvant therapy, in addition to growth hormone, to control the insatiable appetite and morbid obesity seen in this condition.

Inclusion Criteria:

• Diagnosis of PWS confirmed by chromosome analysis
• Ages 5 years to 21 years
• BMI for age ≥ (greater-than or equal to)85th percentile
• Written informed consent and assent obtained and willingness to comply with the study schedule and procedures
• Free T4, Thyroid stimulating hormone (TSH) values in the normal range (either endogenous or with thyroxine replacement)

Exclusion Criteria:

• Patients with any other clinically significant disease that would have an impact on body composition, including diabetes mellitus, chronic inflammatory bowel disease, chronic severe liver or kidney disease or neurologic disorders
• Concomitant use of an investigational drug or Octreotide in the past year
• Use of steroids for longer than 7 days within the past 30 days