XANTHUS' SYMADEX™ SHOWS REMYELINATION IN MULTIPLE SCLEROSIS ANIMAL MODEL

-Results Presented at the International Workshop on Myelin Imaging in Vancouver-

CAMBRIDGE , Mass. , - February 13, 2006 - Xanthus Life Sciences, Inc., today announced that data from a study conducted with a Multiple Sclerosis (MS) animal model demonstrated that Symadex™ permitted remyelination by prevention of inflammatory cell infiltration. Stephen J. Karlik, Ph.D., Professor of Diagnostic Radiology at the University of Western Ontario, London, Ontario presented the research findings on February 10, 2006 at the International Workshop on Myelin Imaging, in Vancouver .

Dr. Karlik is widely recognized for investigating potential new therapies for MS in a specialized animal model of human MS that incorporates both inflammatory and demyelinating properties. Symadex was found to produce remyelination in the study even after 40 days of inflammatory insult by preventing the infiltration of autoreactive cells into the central nervous system. Treatment proved to be effective in both the acute and c hronic presentations of disease.

“The early results from this study showed that the animals in the study, which were paralyzed due to neurological impairment, were able to recover and regain their mobility after treatment with Symadex,” commented Dr. Karlik.

“Symadex is now in Phase 2 trials in oncology and the positive results of this animal model study show the candidate’s potential for treating MS and provide the support needed to advance Symadex towards human trials for MS,” said Michael A. Boss, PhD. Chief Business Officer at Xanthus.

About Symadex™

Symadex (formerly C-1311) is a next-generation investigational drug that has shown a potentially novel, targeted mechanism of action in studies of cancer and autoimmune disease. Symadex was developed to deliver efficacy comparable to the anthracenediones (e.g., Novantrone® ( mitoxantrone)), but with a molecular scaffold intended to reduce the cardio- and hemato-toxicities known to be associated with these active drugs. Additionally, in previous preclinical studies, Symadex has shown early evidence of both oral activity and efficacy in various models of acquired drug resistance and autoimmune disease. The Company is conducting Phase 2 clinical trials with Symadex in several tumor indications and is also exploring the use of Symadex for the treatment of a number of autoimmune diseases, such as Multiple Sclerosis.

About Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic, unpredictable disease of the central nervous system that, according to the National MS Society, affects approximately 400,000 people in the United States and approximately 2.5 million people worldwide. It is a disease typically of young adults, mostly women, with onset typically between 20 and 50 years of age. Each hour someone is newly diagnosed. MS symptoms may include vision problems, loss of balance, numbness, difficulty walking and even complete paralysis.

About Xanthus Life Sciences, Inc.

Xanthus Life Sciences, Inc. is developing a portfolio of novel, clinical-stage, small-molecule oncology drugs 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 such as the studies referred to above 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:

Kari Watson, MacDougall Biomedical Communications, Inc. – kwatson@macbiocom.com or (508) 647-0209

John A. McCarthy, Jr., Senior Vice President & CFO, Xanthus Life Sciences, Inc. – john.mccarthy@xanthus.com or (617) 225-0522, x 125

http://www.xanthus.com/news_2_13_06.htm