Publications

Regulator of G protein signaling 9-2 (RGS9-2) is a protein that is highly enriched in the striatum, a brain region that mediates motivation, movement and reward responses. We identified a naturally occurring 5 nucleotide deletion polymorphism in the human RGS9 gene and found that the mean body mass index (BMI) of individuals with the deletion was significantly higher than those without. A splicing reporter minigene assay demonstrated that the deletion had the potential to significantly decrease the levels of correctly spliced RGS9 gene product. We measured the weights of rats after virally transduced overexpression of RGS9-2 or the structurally related RGS proteins, RGS7, or RGS11, in the nucleus accumbens (NAc) and observed a reduction in body weight after overexpression of RGS9-2 but not RGS7 or 11. Conversely, we found that the RGS9 knockout mice were heavier than their wild-type littermates and had significantly higher percentages of abdominal fat. The constituent adipocytes were found to have a mean cross-sectional area that was more than double that of corresponding cells from wild-type mice. However, food intake and locomotion were not significantly different between the two strains. These studies with humans, rats and mice implicate RGS9-2 as a factor in regulating body weight.

Evaluation of the safety of hormonal preparations for the treatment of female sexual dysfunction is important to assess the benefit-to-risk profile of these drugs and has been strongly encouraged by the Food and Drug Administration. LibiGel (Biosante Pharmaceuticals, Inc., Lincolnshire, IL), a low-dose testosterone gel, is under development for the treatment of hypoactive sexual desire disorder (HSDD) in oophorectomized women. To evaluate the long-term effects of LibiGel on risk for cardiovascular (CV) events, breast cancer, and general safety, a randomized, placebo-controlled clinical study using a novel adaptive design to optimize sample size and power is being conducted. The primary end point of the BioSante LibiGel Safety Study (BLISS) is a composite of CV events including death, nonfatal myocardial infarction, nonfatal stroke, coronary revascularization, hospitalized unstable angina, and venous thromboembolic events. Breast cancer is a coprimary end point. Postmenopausal women (both surgically and naturally) with HSDD and increased risk for CV events will be followed up for up to 5 years postrandomization with an interim data analysis for regulatory approval after the last woman enrolled has been on therapy for at least 12 months. Determination of the number of subjects to enroll is based on an adaptive design that uses interim data to estimate the predictive probability of study success. In agreement with the Food and Drug Administration, LibiGel will be declared safe if the upper limit of the 97.2% CI of the hazard ratio is ≤2.0 or the upper bound of the 97.2% CI for the absolute difference between CV event rates per 100 person-years is ≤1% and the observed hazard ratio is ≤2.0. The BLISS study will define the CV safety profile of low-dose testosterone therapy in the formulation of LibiGel for postmenopausal women with HSDD, and the trial design may provide a paradigm for studies that aim to document long-term safety when the proposed outcome under study is an uncommon adverse event.