GTx Announces Initiation of Phase 2 Clinical Trial of Enobosarm in Stress Urinary Incontinence

— Trial will evaluate orally administered SARM in postmenopausal
women with stress urinary incontinence —

— Objective to determine whether a SARM may increase pelvic floor
muscle mass and potentially improve outcomes in women with SUI —

MEMPHIS, Tenn.–(BUSINESS WIRE)–GTx, Inc. (Nasdaq: GTXI) today announced the initiation of its Phase 2
clinical trial to treat postmenopausal women with stress urinary
incontinence (SUI). The Phase 2 proof-of-concept study of enobosarm
(GTx-024) is the first clinical trial to evaluate a selective androgen
receptor modulator (SARM) for SUI.

“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,” said Kenneth M. Peters, M.D., Chief of Urology at
Beaumont Hospital and the principal investigator in the clinical trial.
“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 is a single center, single-arm, open-label proof-of-concept
Phase 2 clinical trial evaluating the effects of orally administered
enobosarm 3mg in postmenopausal women with SUI. The Company plans to
enroll up to 35 patients and evaluate the safety and efficacy of
enobosarm. The Company anticipates having top-line results in 2016.

The primary endpoint of the trial is the change in frequency of daily
stress urinary incontinence episodes from baseline to week 12. Secondary
efficacy endpoints include accepted measurements of voiding, urethral
pressure profile and change in pelvic floor muscles as measured by
Magnetic Resonance Imaging (MRI).

The rationale for evaluating enobosarm as a treatment for SUI is
supported by preclinical in vivo data demonstrating increases in
pelvic floor muscle mass following treatment with GTx’s SARM compounds,
including enobosarm, as well as human safety and efficacy data from
enobosarm clinical trials involving more than 1,500 subjects. Enobosarm
has been found to be generally safe and well tolerated. Following
results from the proof-of-concept trial, the Company will determine
which GTx SARM compound, including enobosarm, may be further developed
for this indication.

About Stress Urinary Incontinence

Stress urinary incontinence (SUI) refers to the unintentional leakage of
urine during activities that increase abdominal pressure such as
coughing, sneezing or physical exercise. SUI, the most common type of
incontinence suffered by women, affects up to 35 percent of adult women.
There are a variety of treatments that are used to treat SUI in women,
such as behavioral modification and pelvic floor physical therapy,
especially as initial treatment options. As the condition worsens
however, bulking agents and surgical procedures are often the most
widely used treatments.

About the Enobosarm Clinical Development Program

In addition to this proof-of-concept Phase 2 clinical trial in SUI, the
Company is conducting a Phase 2 clinical trial of enobosarm 18mg in
women with androgen receptor positive (AR+), triple negative breast
cancer, as well as a Phase 2 clinical trial of enobosarm 9mg or 18mg in
women with estrogen receptor positive (ER+), AR+ breast cancer.

Previously, enobosarm 9mg has been tested in 22 postmenopausal women
with ER+ metastatic breast cancer in a Phase 2 clinical trial. In total,
enobosarm has been evaluated in clinical trials enrolling over 1500
subjects at doses ranging from 0.1 mg to 100 mg. At all evaluated dose
levels, enobosarm was observed to be safe and well tolerated.

About GTx

GTx, Inc., headquartered in Memphis, Tenn., is a biopharmaceutical
company dedicated to the discovery, development and commercialization of
small molecules for the treatment of cancer, including treatments for
breast and prostate cancer, and other serious medical conditions.

Forward-Looking Information is Subject to Risk and Uncertainty

This press release contains forward-looking statements based upon
GTx’s current expectations. Forward-looking statements involve risks and
uncertainties, and include, but are not limited to, statements relating
to GTx’s planned clinical trial of enobosarm (GTx-024) to treat stress
urinary incontinence (SUI) and its ongoing clinical trials for enobosarm
to treat patients with advanced breast cancer. GTx’s actual results and
the timing of events could differ materially from those anticipated in
such forward-looking statements as a result of these risks and
uncertainties, which include, without limitation, the risks (i) that
clinical trials being conducted or planned to be conducted by GTx may
not be initiated or completed on schedule, or at all, or may otherwise
be suspended or terminated; (ii) that any additional clinical
development of GTx’s product candidate, enobosarm, beyond the planned
clinical trial to treat SUI and its two Phase 2 clinical trials of
enobosarm in patients with AR positive advanced breast cancer is
contingent on GTx entering into new collaborative arrangements with
third parties for such development or otherwise obtaining sufficient
additional capital to permit such development, which it may be unable to
do; or (iii) that GTx may not be able to obtain required regulatory
approvals to commercialize its product candidates in a timely manner or
at all. In addition, GTx will continue to need additional funding
and may be unable to raise capital when needed, which would force GTx to
delay, reduce or eliminate its product candidate development programs
and potentially cease operations. GTx’s actual results and the timing of
events could differ materially from those anticipated in such
forward-looking statements as a result of these risks and uncertainties.
You should not place undue reliance on these forward-looking statements,
which apply only as of the date of this press release. GTx’s quarterly
report on Form 10-Q for the quarter ended September 30, 2015, filed
November 9, 2015, contains under the heading, “Risk Factors”, a more
comprehensive description of these and other risks to which GTx is
subject. GTx expressly disclaims any obligation or undertaking to
release publicly any updates or revisions to any forward-looking
statements contained herein to reflect any change in its expectations
with regard thereto or any change in events, conditions or circumstances
on which any such statements are based.

Contacts

Investors
GTx, Inc.
Lauren Crosby, 901-271-8622
lcrosby@gtxinc.com
or
Media
Red
House Consulting
Denise Powell, 510-703-9491
denise@redhousecomms.com

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