Comparison of Dapagliflozin (DAPA) and Once-weekly Exenatide (EQW), Co-administered or Alone, DAPA/ Glucophage (DAPA/MET ER) and Phentermine/Topiramate (PHEN/TPM) ER on Metabolic Profiles and Body Composition in Obese PCOS Women

Polycystic ovary syndrome is a heterogeneous condition characterized by disordered reproductive and metabolic function which accounts for the myriad of clinical features including androgen excess, chronic anovulation, insulin resistance adiposity, and dyslipidemia. This syndrome is highly prevalent, affecting between 8 and 18% of the female population, depending on the diagnostic criteria used. Hyperandrogenism, ovarian dysfunction and metabolic abnormalities - the main determinants of PCOS - all appear to be involved in a synergistic way in the pathophysiology of PCOS. Women with PCOS are more likely to be obese: between 38 and 88% of women with PCOS are overweight or obese, although PCOS can also manifest in lean women. Obesity, particularly abdominal obesity, plays a central role in the development of PCOS, and exacerbates the reproductive and metabolic dysfunction. Rather than absolute body weight, it is the distribution of fat that is important with central (visceral) adiposity being a risk factor. Visceral adipose tissue is more metabolically active than subcutaneous fat and the amount of visceral fat correlates with insulin resistance and hyperinsulinemia. Weight gain is also often an important pathogenic factor, with PCOS usually becoming clinically manifest in women with a presumable genetic predisposition for PCOS who subsequently gain weight. Therefore, environmental (particularly dietary) factors are important. However, BMI is also influenced by genetic factors such as the fat mass and obesity-associated protein, and obesity is a highly heritable condition. Therefore, the weight gain responsible for the manifestation of PCOS in many women with this condition is itself influenced by genetic factors. Ethnicity, genetic background, personal and family history, degree of obesity must all be taken into account because they might aggravate or even trigger metabolic disturbances women with PCOS. Moreover, the incidence of glucose intolerance, dyslipidemia, gestational diabetes, and type 2 diabetes (DM2) is increased in women with PCOS at all weight levels and at a young age. PCOS may be a more important risk factor than ethnicity or race for glucose intolerance in young women. The exact factors responsible for this excess risk in women with PCOS have not been identified; family history of DM 2, obesity, insulin resistance, beta cell (ß-cell) secretory dysfunction, and hyperandrogenism are possible candidates. With better understanding of its pathophysiology, the metabolic consequences of the syndrome are now evident. Therefore, these patients need to be followed up even after their presenting complaint has been adequately resolved.

Lifestyle modification is a key component for the improvement of reproductive function for overweight, anovulatory women with PCOS. Even a modest weight loss 5% of total body weight can restore ovulation in overweight women with PCOS. Features of PCOS (e.g., hirsutism, testosterone levels, insulin resistance, menstrual cyclicity and ovulation) showed marked improvements, and PCOS frequently resolved after substantial weight loss induced by bariatric surgery. Recently a number of anti-diabetes medications have been approved which facilitate weight loss and improve the underlying insulin resistance. We reported that treatment with the glucagon like peptide -1 (GLP-1) agonist, exenatide for 24 weeks was superior to single agent metformin treatment in improving insulin action and reducing body weight and hyperandrogenism in obese women with PCOS. We further observed exenatide treatment significantly improved first-phase insulin responses to oral glucose administration. Since aberrant first-phase insulin secretion and impaired suppression of endogenous glucose production are major contributors to postprandial hyperglycemia and development of type 2 diabetes, the effects of exenatide once weekly [EQW (2 mg)] to target these defects, and normalize glucose excursions are likely to be clinically significant in obese patients with PCOS. Sodium/glucose cotransporter 2 (SGLT-2) inhibitors are the newest class of medications for diabetes management that have not been investigated for use in the women with PCOS. The SGLT2 inhibitor, dapagliflozin [DAPA (10 mg/day)] has an insulin-independent action, promotes weight loss, has a low incidence of hypoglycemia, and complements the action of other antidiabetic agents. The loss of glucose with attendant caloric loss contributes to weight loss; in addition, improvements in β cell function have been seen. Because the SGLT2 inhibitors have a distinct mechanism of action that is independent of insulin secretion, the efficacy of this class of drugs is not anticipated to decline in the presence of severe insulin resistance. The weight loss seen with SGLT2 inhibitors is similar to that seen with glucagon-like peptide 1 agonists, and may be more acceptable because they are oral agents. The resulting weight loss will further assist in decreasing insulin resistance, leading to increased glucose disposal thus contributing to an increased insulin secretion-insulin sensitivity (ISSI) index, the primary outcomes measure.

The non-diabetic female with PCOS offers a unique model to study the relationship between insulin resistance and adiposity. Women with PCOS demonstrate abnormal body composition characterized by a greater percent body fat, body fat mass, and increased ratio of fat to lean mass (F/L ratio). Studies using dual-energy X-ray absorptiometry (DEXA) methodology report a higher degree of metabolic dysfunction in patients with PCOS which appears be directly associated with their higher F/L ratio. Given that monotherapy and combined therapy with exenatide once weekly (EQW),and dapagliflozin (DAPA) along with DAPA/ metformin XR therapy are associated with weight loss introduces a confounder to the current study since it prevents distinguishing direct effects of the compounds on β-cell function vs. effects due to reduced adiposity. To control for loss of body mass and provide appropriate intervention in the remaining study arm we propose the use of a comparator weight loss drug alone, combination phentermine (PHEN)/topiramate (TPM) extended release (ER). To avoid the confounding relationship of body fat and insulin resistance, we will enroll only obese non-diabetic women with PCOS. All patients will receive diet and lifestyle counselling, including advice on exercise, according to usual clinical routine commencing during the lead-in period and continuing throughout the study We propose a randomized, single-blind, parallel 5 treatment group 24-week trial designed to directly compare the therapeutic effects of exenatide once weekly (EQW), dapagliflozin (DAPA), EQW plus DAPA, combined DAPA/metformin ER and the weight loss medication, phentermine/topiramate extended release (PHEN/TPM ER) on metabolic and endocrinological parameters in obese non-diabetic women with PCOS.