MacroArray Technologies Announces the Identification of a Urine Diagnostic Marker for High Grade PIN, a Precancerous Prostate Lesion.

PHILADELPHIA -- MacroArray Technologies, LLC, today announced the identification of a novel urine protein called ABCA5 as a sensitive diagnostic marker for high grade prostatic intraepithelial neoplasia (PIN), the precancerous lesion of the prostate. Details of the marker's identification were published in the February issue of Clinical Cancer Research.

Men with high grade PIN are at the highest risk for developing prostate cancer with approximately 50% developing prostate cancer within three years of diagnosis and 80% within eight years. Currently, high grade PIN can only be diagnosed by prostate biopsy in patients who present with an elevated serum PSA or an abnormal digital rectal exam. About 5-10% of patients who undergo a prostate biopsy will be found to have high grade PIN only. In the United States, 1.1 million men have been diagnosed with high grade PIN. The successful development of a non-invasive urine or blood diagnostic test for high grade PIN could help to identify an estimated 14 million at risk men who unknowingly harbor this premalignant lesion and may not have an elevated serum PSA.

"The assay for the ABCA5 protein offers a convenient and noninvasive way to detect premalignant high grade PIN cells," said Mark E. Stearns, Chief Scientific Officer of MacroArray Technologies. "The ABCA5 assay, if successfully developed and approved for marketing by the FDA, would be the first urine diagnostic marker capable of detecting high grade PIN and therefore represents an important scientific and medical advancement for the early detection of prostate cancer."

In the Clinical Cancer Research paper,"The ABCA5 Protein: A Urine Diagnostic Marker for Prostatic Intraepithelial Neoplasia," Hu, Y et al. (Clin Cancer Res, February 2007, volume 13, pages 929 - 38) report that ABCA5 protein is overexpressed in high grade PIN tissue and is detected in the urine of patients with high grade PIN, whereas it is not expressed appreciably in prostate cancer or benign prostatic hyperplasia . A "blinded" study using an ELISA test determined that ABCA5 was a highly sensitive urine marker for high grade PIN in patients with biopsy confirmed high grade PIN (n=107; >98% sensitivity) and was present at very low levels in the urine of patients with biopsy negative high grade PIN (n=79; >86% specificity).

GTx, Inc. (Nasdaq: GTXI), supplied to MacroArray urine and serum samples from patients with high grade PIN enrolled in Phase IIb and Phase III clinical trials to assist MacroArray in its development and validation of a noninvasive test for high grade PIN. GTx has no commercial interest in any test which may be developed by MacroArray, nor does it have control over the development of such a test. GTx is conducting a pivotal Phase III clinical trial of ACAPODENE[R] (toremifene citrate) 20 mg for the prevention of prostate cancer in men with high grade PIN. The primary endpoint of the trial is a reduction in prostate cancer incidence. The trial, which is being conducted under a SPA with the FDA, is designed as a 36 month study but provides for an interim efficacy analysis after a certain number of cancer events have occurred. GTx anticipates conducting an interim efficacy analysis by the first quarter of 2008. If ACAPODENE 20 mg achieves its efficacy endpoint in this analysis, GTx will file a new drug application.

About GTx

GTx, Inc., headquartered in Memphis, Tenn., is a biopharmaceutical company dedicated to the discovery, development and commercialization of therapeutics for cancer and serious conditions related to men's health. GTx's lead drug discovery and development programs are focused on small molecules that selectively modulate the effects of estrogens and androgens. GTx is developing ACAPODENE[R] (toremifene citrate), a selective estrogen receptor modulator, or SERM, in two separate clinical programs in men: first, a pivotal Phase III clinical trial for the treatment of serious side effects of androgen deprivation therapy for advanced prostate cancer, and second, a pivotal Phase III clinical trial for the prevention of prostate cancer in high risk men with high grade prostatic intraepithelial neoplasia, or PIN. GTx has licensed to Ipsen Limited exclusive rights in Europe to develop and commercialize ACAPODENE[R]. GTx also is developing ostarine, a first-in-class selective androgen receptor modulator, or SARM. GTx plans to initiate a Phase IIb ostarine clinical trial for cancer cachexia by the summer of 2007. GTx plans to initiate a Phase IIb ostarine clinical trial for the treatment of end stage renal disease muscle wasting by the end of 2007. GTx believes that ostarine also has the potential to treat a variety of other indications associated with muscle wasting and bone loss including frailty and osteoporosis.

About MacroArray Technologies, LLC

MacroArray Technologies is an early stage biotechnology company formed to capitalize on the growing need for more efficient and effective technology to rapidly identify and develop novel diagnostic markers for the early detection of PIN plus the detection of early stage cancer and other diseases and novel therapeutics linked to the diagnostic markers for a variety of cancers. Core technologies of the company include proteomics platform for novel marker discovery; DNA-protein binding technology; proprietary methods for cloning/identification of genes/proteins; proprietary immunoassays for tissue/fluid markers; linking diagnostic markers to therapeutics; 'DNA ZYM' (Ribozyme-like) therapeutic agents for the treatment of cancer; and broad patent application covering discovery process, diagnostics, and therapeutics applications.

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. 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 that (i) GTx will not be able to commercialize its product candidates if clinical trials do not demonstrate safety and efficacy in humans; (ii) GTx may not able to obtain required regulatory approvals to commercialize its product candidates; (iii) GTx's clinical trials may not be completed on schedule, or at all, or may otherwise be suspended or terminated; (iv) GTx could utilize its available cash resources sooner than it currently expects and may be unable to raise capital when needed, which would force GTx to delay, reduce or eliminate its product development programs or commercialization efforts; and (v) GTx has no control over the development by MacroArray or any other diagnostic company that GTx is collaborating with for the development of a diagnostic test for high grade PIN, and no such test may be developed. You should not place undue reliance on these forward-looking statements, which apply only as of the date of this press release. GTx's prospectus supplement filed with the U.S. Securities and Exchange Commission (the "SEC") pursuant to Rule 424(b)(5) on December 13, 2006, 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.