US-based biopharmaceutical firm GTx has started its Phase II trial of enobosarm (GTx-024) to treat postmenopausal women with stress urinary incontinence (SUI).

SUI refers to unintentional urination during activities that increase abdominal pressure, such as coughing, sneezing or physical exercise.

The Phase II proof-of-concept trial is the first clinical study to evaluate a selective androgen receptor modulator (SARM) for SUI.

The proof-of-concept trial will assess the effects of orally administered enobosarm 3mg in postmenopausal women with SUI.

Around 35 patients will be enroled in the trial, which will evaluate the safety and efficacy of enobosarm, and the company expects to release top-line results this year.

Beaumont Hospital Urology chief and the principal investigator in the clinical trial Kenneth Peters said: “Given the selective anabolic activity of enobosarm, we are looking forward to evaluating its potential to augment pelvic floor muscle response and potentially improve outcomes for women with stress urinary incontinence.

“I would welcome a safe and effective treatment option, especially since existing non-surgical options are extremely limited and, at times, only marginally effective.”

The trial’s primary endpoint is the change in frequency of daily stress urinary incontinence episodes from baseline to week 12.

Secondary efficacy endpoints will include accepted measurements of voiding, urethral pressure profile and change in pelvic floor muscles as measured by magnetic resonance imaging (MRI).

The initiation of this Phase II trial is supported by preclinical in vivo data showing increases in pelvic floor muscle mass.

This data was acquired following treatment with the company’s SARM compounds, as well as enobosarm clinical trials involving over 1,500 subjects.

According to the company, enobosarm has been found to be generally safe and well tolerated.

After the proof-of-concept trial, the company will determine which GTx SARM compound may receive further development.

The company is also conducting a Phase II trial of enobosarm 18mg in women with androgen receptor positive (AR+), triple negative breast cancer, as well as a Phase II trial of enobosarm 9mg or 18mg in women with estrogen receptor positive (ER+), AR+ breast cancer.