Xanthus Announces Oral Fludarabine NDA Accepted for Review by U.S. FDA

CAMBRIDGE, Mass.--(Business Wire)--Xanthus Pharmaceuticals, Inc., a privately-held oncology and
autoimmune disease drug development company, today announced that its
New Drug Application (NDA) for fludarabine phosphate oral tablets
(oral fludarabine) was accepted for filing by the U.S. Food and Drug
Administration (FDA) for the treatment of relapsed B-cell chronic
lymphocytic leukemia (CLL). Filing of the NDA indicates that the
registration package is sufficiently complete to allow for a thorough
review of the data supporting the safety profile and effectiveness of
oral fludarabine. Earlier this month Xanthus announced that the FDA
granted Orphan Drug Designation for oral fludarabine for B-cell CLL.
Xanthus licensed the exclusive right to develop and commercialize oral
fludarabine in the United States from Schering AG (now Bayer Schering
Pharma AG) in October of 2006.

"Currently patients with chronic CLL undergoing fludarabine
treatment in the United States receive the drug intravenously.
Acceptance of the NDA application is a critical next step in our
effort to provide these individuals with a more patient-friendly
delivery option," said Richard Dean, Ph.D., CEO of Xanthus. "With the
convenience of oral dosing and a strong body of clinical efficacy and
tolerability data already behind it, we believe oral fludarabine
represents an exciting opportunity for Xanthus."

About CLL and Oral Fludarabine

Chronic lymphocytic leukemia (CLL) is a cancer of the white blood
cells and bone marrow which arises predominantly in older age groups.
CLL is the most prevalent leukemia and according to the American
Cancer Society, approximately 15,300 new CLL cases were diagnosed in
the United States in 2007. Oral fludarabine is currently marketed by
Bayer Schering Pharma AG in the European Union and Canada for the
treatment of relapsed B-cell chronic lymphocytic leukemia. Intravenous
(IV) fludarabine has been widely available for a number of years in
the United States and other countries as a treatment for patients with
CLL. The approval for the oral formulation was extended to first-line
treatment in Europe in November 2004. Bayer Schering Pharma AG studied
oral fludarabine in several clinical trials as a first- and
second-line therapy, where it exhibited an efficacy and tolerability
profile similar to that of the IV formulation.

About Xanthus Pharmaceuticals, Inc.

Xanthus Pharmaceuticals, Inc. is developing a portfolio of novel,
clinical-stage, small-molecule oncology candidates through a
management team whose accomplished track record encompasses all
aspects of drug development, from discovery through regulatory
approval and commercialization. The Company is applying its expertise
both to advance its current pipeline and expand it into indications of
unmet medical need beyond oncology.

Xanthus is headquartered in Cambridge, Massachusetts with an
additional facility in Montreal, Quebec. More information is available
at www.xanthus.com.

This press release contains forward-looking statements concerning
Xanthus that involve a number of risks and uncertainties. For this
purpose, any statements contained herein that are not statements of
historical fact may be deemed to be forward-looking statements.
Without limiting the foregoing, the words, "believes," "anticipates,"
"plans," "expects," "estimates," "intends," "should," "could," "will,"
"may," and similar expressions are intended to identify
forward-looking statements. There are a number of important factors
that could cause Xanthus' actual results to differ materially from
those indicated by such forward-looking statements, including risks as
to whether results obtained in early clinical studies or in
preclinical studies will be indicative of results obtained in future
clinical trials or warrant additional trials; whether products based
on Xanthus' technology will advance through the clinical trial process
and receive approval from the United States Food and Drug
Administration or equivalent foreign regulatory agencies; whether the
company will have the cash resources to develop and commercialize its
products; and whether the patent and patent applications owned or
licensed by Xanthus will protect the Company's technology and prevent
others from infringing it. Xanthus disclaims any intention or
obligation to update any forward-looking statements.

Contacts:
For Xanthus Pharmaceuticals, Inc.
MacDougall Biomedical Communications, Inc.
Sarah Cavanaugh, 781-235-3060
scavanaugh@macbiocom.com
or
Xanthus Pharmaceuticals, Inc.
Lisa Terry, 617-225-0522, x 105
lisa.terry@xanthus.com

Copyright Business Wire 2008