enobosarm (Ostarine®; GTx-024)
enobosarm is an oral selective androgen receptor modulator that GTx is developing for the prevention and
treatment of muscle wasting in patients with non-small cell lung cancer.
About Muscle Wasting, a Common Cancer Related Symptom
Muscle wasting is a common cancer related symptom which can begin early in the course of a patient’s
malignancy resulting in decline in physical function and other detrimental clinical consequences. Muscle wasting and muscle
weakness are also side effects of many chemotherapy drugs. There are no drugs approved for the prevention and treatment of muscle wasting in patients with cancer.
At diagnosis, approximately 50% of advanced non-small cell lung cancer (NSCLC) patients have severe muscle loss,
and approximately 70% of these patients will lose muscle before death. Muscle weakness and functional limitations are highly prevalent,
with 88% of NSCLC patients reporting difficulty climbing stairs, lifting and carrying 10 lbs, walking a quarter mile, or stooping,
crouching or kneeling. Muscle loss is a predictor of performance status, tolerability to cancer treatment, progression free survival and overall survival.
Limitations in physical function predict the ability of a NSCLC patient to tolerate chemotherapy, and patients with functional limitations
are less likely to be offered treatment. Functional status is also a predictor of survival.
To date, GTx has evaluated enobosarm in eight clinical trials involving approximately 600 subjects including three efficacy studies.
A four month Phase IIb enobosarm clinical trial enrolled 159 patients with NSCLC, colorectal cancer, breast cancer, non-Hodgkin’s lymphoma,
or chronic lymphocytic leukemia. The study met its primary endpoint of absolute change in total lean body mass (muscle) compared to placebo
and the secondary endpoint of muscle function (performance). The incidence of serious adverse events, deaths and tumor progression were
similar among placebo and the treatment arms. The most common side effects reported among all subjects in the trial were fatigue,
anemia, nausea and diarrhea.