FDA Approves Pathvysion Breast Cancer Test

Company Contacts: (www.vysis.com) John L. Bishop James J. Habschmidt President, CEO Vice President & CFO 630/271-7000 630/271-7000

Media Relations Charles Versaggi, Ph.D. Versaggi Biocommunications(r) 415/547-1320 mail@versaggibio.com

FOR IMMEDIATE RELEASE

FDA APPROVES VYSIS PATHVYSION(tm) BREAST CANCER TEST TO DETECT AND QUANTIFY HER-2 GENE

Experts Urge Routine HER-2 Testing With FISH-Based Assay for Therapy Selection and Improved Patient Survival

DOWNERS GROVE, Ill., December 14, 1998 -- Vysis, Inc. (Nasdaq: VYSI) today announced that its PathVysion HER-2 DNA Probe Kit to detect and quantify the HER-2 gene in breast cancer patients was approved by the U.S. Food and Drug Administration (FDA). Set for immediate U.S. and European availability, the kit is under review for marketing in France by the Agence du Medicament.

"We're extremely pleased with the FDA's rapid approval of our leading-edge PathVysion test, which we believe will have a positive impact on the fight against breast cancer," said John L. Bishop, president and chief executive officer of Vysis. "This approval gives Vysis immediate access to a potential $36 million annual market opportunity in the U.S. and Western Europe, representing a significant near-term revenue opportunity for our company. We are prepared to initiate product shipments without delay and have manufacturing capacity to fully cover market demand."

The presence of multiple copies of the HER-2 gene, and the corresponding over-expression of its protein, plays a pivotal role in the rapid growth of tumor cells in 25-30 percent of breast cancer patients. HER-2 positive-breast cancer patients experience rapid tumor growth, resistance to therapy and potentially decreased survival. Determination of HER-2 status is a critical tool for selecting therapeutic options, because certain breast cancer treatments are more appropriate when multiple copies of the gene are found.

"In a head-to-head comparison with other FDA-approved tests in our own laboratory, the Vysis test was found to be superior. In my opinion, it is the most reliable and accurate method of assessing HER-2 status in breast cancer tissue specimens," said Dennis Slamon, M.D., Ph.D., Chief, Division of Hematology and Oncology, University of California, Los Angeles School of Medicine and Director, Revlon/UCLA Women's Cancer Research Program. Dr. Slamon was the first to identify the association between the HER-2 gene amplification and clinical behavior of the tumor. "For a woman who has breast cancer, it's important to know her HER-2 status. It's fairly clear now that it should be part of the routine armamentarium for treating this disease.

"The best test for measuring HER-2 status is one that directly measures this at the DNA level," added Dr. Slamon. "HER-2 protein over-expression in the absence of amplification rarely happens. If you look at antibody-based tests that measure over-expression of the protein in paraffin-embedded material, which is how the vast majority of material comes to you, the false negative rate ranges from 15 percent to 20 percent -- and that's with a good antibody reagent. FISH gets beyond all that. It tells you exactly how many copies of this gene there are in the tumor, whether or not the gene is truly amplified, and then by extension, if the tumor is over-expressed."

PathVysion Test Directly Measures HER-2 DNA

The PathVysion HER-2 test is one of the first examples of genomic disease management, where a direct genetic test enables assessment of a patient for determination of the most appropriate therapy based upon their genetic profile. Based on Vysis' patented Fluorescence In Situ Hybridization (FISH) technology, the new test enables one to directly detect both the HER-2 gene and the chromosome 17 on which the gene resides. Patients with more than two copies of chromosome 17 do not represent true amplification of the HER-2 gene. Thus, the ability to simultaneously detect chromosome 17 provides a built-in control to determine true ampli-fication of the HER-2 gene. This added capability is unique to Vysis' patented technology.

Responsible for $6 billion in direct medical costs annually in the United States, breast cancer is the most common form of cancer among women and the leading cause of cancer-related deaths among women age 35 to 54, according to the American Cancer Society. About 180,000 new cases of breast cancer are diagnosed each year in the United States. Some 1.7 million American women are currently living with the disease. The European Community has a similar incidence and prevalence.

Selma Schimmel, president and CEO of Vital Options, the nation's leading cancer support, advocacy and communications organization, said, "A diagnosis of cancer leaves one feeling completely out of control and powerless. Getting information is what grounds you -- it's what gives you hope. As a carrier of the amplified HER-2 gene and a breast cancer survivor, I can say that HER-2 testing using the most reliable and accurate technology is incredibly important because it provides a whole new opportunity and sense of hope for treatment."

How the PathVysion HER-2 Test Works

The PathVysion HER-2 DNA Probe Kit utilizes a DNA probe -- a small piece of DNA directly labeled with a light-emitting fluorescent marker that binds to the HER-2 gene within the tumor cell-nucleus. Upon attaching to the HER-2 gene, the probe glows red-orange, while a control probe for chromosome 17 emits green light. Counting the ratio of red-orange dots to green dots, the clinician can easily determine whether or not the HER-2 gene has been amplified.

FISH-based tests can be run with equipment routinely found in most pathology laboratories. In order to accommodate the anticipated demand for the HER-2 test, Vysis is developing an automated instrument to enhance laboratory throughput. FISH assays are currently reimbursable by third-party payers.

HER-2 Positive Patients Should Receive More Aggressive Treatment

Vysis' clinical trial involved 524 patients taken from 1,549 node-positive patient specimens from a previous study conducted under the direction of The Cancer and Leukemia Group B (CALGB), one of three multidisciplinary cooperative cancer treatment groups partially funded by the National Cancer Institute (NCI). Patients received one of three different treatments consisting of different doses of cyclophosphamide, adriamycin and 5-fluorouracil (CAF).

The study demonstrated a statistically significant interaction between HER-2 status and dose schedule of CAF. Patients with amplification of the HER-2 gene benefit from aggressive treatment with higher doses of adriamycin (doxorubicin)-based therapy (CAF), while those with normal HER-2 levels do not benefit from the aggressive therapy. These women should be treated with the lowest possible dose to achieve similar clinical outcomes and reduce the risk of adverse side effects such as debilitating cardiotoxicity.

Vysis, Inc. of Downers Grove, Ill., is a genomic disease management company that develops, commercializes and markets clinical products providing information critical to the evaluation and management of cancer, prenatal disorders and other genetic diseases. It currently markets clinical products cleared by the U.S. Food and Drug Administration and the French Agence du Medicament, and a line of research products, imaging workstations and other instruments for genetic analysis. The company has direct sales operations in the United States and Europe, a marketing partnership in Japan with Fujisawa Pharmaceutical Co., and a worldwide distribution network.

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Such statements are subject to inherent uncertainties and risks which could cause actual results to vary materially from suggested results. The company disclaims any obligation to update any forward-looking statement in this press release.

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