Nexell Therapeutics Cytonex In Vitro Diagnostic Kit Poised to Play Greater Role in Assessing Breast Cancer Relapse Risk.

Business Editors and Health/Medical Writers

IRVINE, Calif.--(BW HealthWire)--March 1, 2000

New England Journal of Medicine Study Confirms Prognostic Value

of Cytokeratin-positive Cell Detection in Bone Marrow

Nexell Therapeutics Inc. (NASDAQ:NEXL), one of the world's leading suppliers of therapeutic and diagnostic products based on stem cell technology, announced today that it is actively pursuing the implications of a German study published in the February 24, 2000, edition of the New England Journal of Medicine that found a strong correlation between the presence of so-called cytokeratin-positive cells in the bone marrow of breast cancer patients and their risk of cancer relapse(1).

In an editorial accompanying the study, Barbara Smith, MD, of Massachusetts General Hospital in Boston, MA, concluded that the evaluation of bone marrow samples from breast cancer patients at time of surgery might become an important component of disease staging. She stated that such immunocytochemical testing, along with traditional lymph node staging, may help to identify a subgroup of patients who are cytokeratin-negative and therefore at low risk for relapse. According to Dr. Smith, such patients may not require aggressive treatment, such as chemotherapy.

In 1999, Nexell Therapeutics introduced its first in vitro diagnostic kit, the Cytonex(TM) ImmunoCytoChemistry Staining Kit. The Cytonex(TM) Kit is the only FDA-listed Class I-exempt diagnostic kit on the U.S. market for the detection of cytokeratin-positive cells in bone marrow and blood specimens. In the clinic, this restricted in vitro diagnositic kit is intended to be used adjunctively to support conventional histological diagnosis. The Cytonex(TM) Kit contains the same type of cytokeratin monoclonal antibody used by the authors of the study.

"We are very intrigued by the promising results presented by Dr. Braun and his colleagues. Many research studies have concluded that the presence of cytokeratin-positive cells in the marrow of breast cancer patients is clinically relevant. But this impressive study has provided detailed analyses that show that the presence of these cells alone, in the absence of other signs of tumor spread, may provide important prognostic information," said Amy Ross, PhD, Vice President of Diagnostics at Nexell Therapeutics and developer of the Cytonex(TM) Kit. "We anticipate that use of the Cytonex(TM) Kit in additional studies may help to further our understanding of the role these cytokeratin-positive cells play in the prognosis and management of breast cancer."

The study, which consisted of 552 women with newly diagnosed breast cancer, was performed at three university medical centers in Germany. All of the women had bone marrow biopsies taken at the time of breast cancer surgery. The marrow specimens were tested for the presence of cytokeratin-positive cells. Cytokeratins are specific protein markers of cells that are derived from glandular tissues such as breast. Cytokeratins are not found in blood or bone marrow cells. The researchers used a pathology test known as immunocytochemistry to stain the marrow specimens for the presence of cytokeratin-positive cells. Using such methods, cytokeratin-positive cells stain red against a background of unstained marrow cells.

The German researchers found cytokeratin-positive cells in 36% of all the bone marrow samples tested from women with newly diagnosed stage I, II, or III breast cancer. Of particular interest, cytokeratin-positive cells in the marrow were found in 33% of the women who were diagnosed as lymph node-negative for tumor cells by conventional pathological analysis. Statistical analyses at 48 months of follow-up revealed that the presence of these cells in the marrow was an independent prognostic predictor of both breast cancer relapse at a distant site (e.g., bone) and death from the disease.

Nexell Therapeutics Inc.

Located in Irvine, California, Nexell Therapeutics Inc. (Nasdaq:NEXL) is a cell therapy company whose mission is to put the healing power of the cell into the hands of physicians. Nexell is developing and marketing innovative ex vivo cell therapies and in vitro diagnostics for cancer, autoimmune, metabolic and genetic diseases. Nexell's lead product, the Isolex(R) 300i Magnetic Cell Selection System, is the only FDA approved device commercially available for the selection of hematopoietic stem cells and the removal of tumor cells from autologous peripheral blood as a component of aggressive cancer treatment. In addition, Nexell markets the Cytonex(TM) ICC Staining Kit and an extensive line of cell therapy preparation, storage and expansion products including the Cryocyte(TM), SteriCell(R) and Lifecell(R) brands.

The Private Securities Litigation Reform Act of 1995 provides a "safe harbor" for certain forward-looking statements. The forward-looking statements contained in this release are subject to certain risks and uncertainties. Actual results could differ materially from current expectations. Among the factors which could affect the Company's actual results and could cause results to differ from those contained in the forward-looking statements contained herein are: the timely commencement and success of the Company's clinical trials and other research endeavors, delays in receiving FDA or other regulatory approvals, the development of competing therapies and/or technologies, the terms of any future strategic alliances, the possible need for additional capital, and any additional factors described from time to time in the Company's filings with the SEC.

(1) Braun S, Pantel K, Muller P, et. al. Cytokeratin-positive cells in the bone marrow and survival of patients with stage I, II, or III breast cancer. N Engl J Med 2000; 342:525-33.

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