Ostarine increases lean body mass and improves physical performance in healthy elderly subjects: Implications for cancer cachexia patients

9119 Background: Cancer cachexia results in selective loss of skeletal muscle resulting in weakness, reduced physical activity and a lower quality of life. Cancer cachexia also diminishes response to chemotherapy and survival. Anabolic steroids appear to increase weight and muscle mass in cancer patients, but have the potential for masculinization in women and prostate stimulation in men. A new class of non-steroidal selective androgen receptor modulators (SARMs) is being developed for use in cancer cachexia. SARMs are designed to have predominately anabolic activity in muscle and bone with minimal androgenic effects in most other tissues. We conducted a randomized phase II proof of concept study of ostarine, the first-in-class SARM, in healthy postmenopausal women and elderly men prior to intitiating a phase II study in cancer patients. Methods: Sixty elderly men (mean age 66 years) and 60 postmenopausal women (mean age 63 years) were randomly assigned to ostarine 0.1, 0.3, 1 mg, 3 mg or placebo for three months. The primary end point was change from baseline to three months in total lean body mass (LBM) measured by dual energy x-ray absorptiometry (DXA). The key secondary end point was a stair climb functional performance test that measured speed and power exerted. Evaluations included laboratory safety assessments and additional assessments of androgenic activity including PSA, sebum production and luteinizing hormone. Results: Ostarine treatment resulted in a dose dependent increase in total LBM, with an increase of 1.4 kg compared to placebo (p<0.001) at the 3 mg dose. Increased LBM translated to an improvement in the stair climb test in both speed (+15.5% ± 12.9 faster time, p=0.006) and power (+25.5% ± 20.3 watts, p=0.005). There were no serious adverse events reported. There were no significant changes in PSA, sebum production or luteinizing hormone. Conclusions: Ostarine improves LBM and physical performance in healthy older men and women. Ostarine had no unwanted androgenic side effects. A phase II study is planned to evaluate the safety and efficacy of ostarine in patients with cancer cachexia. No significant financial relationships to disclose.