GTx Shares Nosedive as Muscle Wasting Drug Misses Endpoints

Andrew Klips  |

Shares of GTx, Inc. (GTXI) jettisoned more than 60 percent to start Monday trading after the Memphis-based drug maker disclosed results from two late-stage clinical trials of enobosarm showing that the drug came up short of expectations. The phase 3 POWER trials, which recruited about 325 patients at 80 clinical sites, were evaluating enobosarm as a potential new therapy to prevent and treat muscle wasting in chemotherapy patients with non-small cell lung cancer (NSCLC), the most prevalent form of the disease.  The stage 3 or 4 NSCLC patients were treated with a placebo or daily doses orally of 3 mg of enobosarm under the pretense that if patients can keep muscle mass, they will live longer.

The drug missed on its primary endpoints of lean body mass and physical function in both POWER1 and POWER2. GTx did note that enobosarm was safe, well tolerated and provided a benefit over the placebo arm with regards to lean body mass in both trials.  The results for physical function were inconsistent between the trials.  The most common adverse events included nausea, anemia and vomiting, amongst other reactions.

Understandably disappointed with the endpoint miss, Dr. Mitchell Steiner, chief executive of GTx, remained optimistic in saying, “we are encouraged by the unambiguous effect of enobosarm on muscle and we are confident that it will translate to clinical benefit and potentially increase survival in patients with non-small cell lung cancer.”

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Also seeing the shiny side of the coin, Carla Prado, Ph.D., Assistant Professor, Nutrition, Food and Exercise Sciences at Florida State University, commented, “Data from the POWER trials provide compelling evidence that enobosarm maintains or increases muscle.”  Dr. Prado added, “Loss of muscle, independent of weight loss, is a common and often occult feature of cancer, and is acknowledged as a remarkable and powerful prognostic indicator of shorter survival.”

There are currently no FDA-approved drugs for muscle wasting in cancer patients. 

GTx says that they will be setting up meetings with the U.S. Food and Drug Administration and European authorities to discuss a path going forward with enobosarm.

This isn’t the first time that shares of GTXI were lambasted on bad drug news.  In February 2012, the company had to put three clinical trials of prostate cancer drug capesaris temporarily on the shelf because of elevated risk of blood clots.  Shares shed about 50 percent on the news, but slowly recovered all the losses (and then some) subsequent to the FDA lifting its hold three months later.  Trials of Capesaris are currently in the second phase of the three required by the FDA.  GTx is also in early clinical trials with GTx-024 and GTx-027 for breast cancer patients.

Shares plunged at the opening bell Monday to as low as $1.31 from Friday’s close at $4.15, a 69-percent drop.  A little of the ground has been made-up, with shares trading at $1.50 – for a loss of 64 percent – two hours into the session.  Shares were essentially flat in 2013 as of Friday’s close and well off of 52-week highs of $7.24 printed in June. 

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