Wednesday, April 11, 2007


- Research project to focus on Xanthus’ novel class of FLT3 inhibitors for autoimmune diseases - CAMBRIDGE, Mass., April 11, 2007 - Xanthus Pharmaceuticals, Inc. today announced that the company has acquired an exclusive worldwide license to a patent estate from Johns Hopkins University for treating immune-related disorders by inhibiting the FLT3 tyrosine kinase. FLT3 is highly expressed on dendritic cells, which are responsible for the stimulation of T cells. In preclinical studies conducted by Johns Hopkins researchers, FLT3 signaling modulated autoimmune responses, suggesting that inhibition of the FLT3 pathway may reverse the course and severity of autoimmune disease. Xanthus and Johns Hopkins have also initiated a research project to assess novel compounds for FLT3 inhibitory activity and the downstream pathways relevant to a range of autoimmune diseases. The research program will focus on a new class of compounds being developed by Xanthus,
imidazoacridinones, which includes Symadex™. Symadex™ is currently in Phase 2 clinical trials in oncology and Xanthus is exploring its use for the treatment of a number of autoimmune diseases where early preclinical studies have shown encouraging signs of activity.

“The group at Johns Hopkins is comprised of world-class leaders in the FLT3 field, including Drs. Katharine Whartenby and Donald Small, who discovered the role of FLT3 inhibitors in autoimmune disorders. This license deal and research project are important steps for Xanthus as we build upon our early findings that Symadex™ and our other imidazoacridinones have the potential to be developed into an important new class of autoimmune therapies,” said Michael A. Boss, Ph.D., Xanthus’ Chief Business Officer.

“Inhibiting dendritic cells by first blocking FLT3 would represent a novel way of treating immune-related disorders by stopping unwanted activity at its point of initiation. If successful, this approach would be a significant therapeutic improvement because it appears to leave the normal immune response intact,” said Alfred M. Ajami, Ph.D., Xanthus’ Chief Scientific Officer.

In a prior study from the Johns Hopkins researchers (PNAS, November 15, 2005, vol. 2, no. 46, 16741- 16746), inhibition of FLT3 signaling induced dendritic cell death in mice and in human cell cultures, making the FLT3 pathway a potential target for immune modulation. Additionally, FLT3 inhibition significantly improved the course of existing disease in a mouse model of multiple sclerosis, suggesting its potential as an autoimmune disease treatment. This latter finding from John Hopkins supports similar experimental observations reported recently by Xanthus and collaborating researchers.
About Xanthus Pharmaceuticals, Inc.

Xanthus Pharmaceuticals, Inc. is developing a portfolio of novel, clinical-stage, small-molecule therapeutic candidates through a management team whose accomplished track record encompasses all aspects of drug development, from discovery through regulatory approval and commercialization.

Xanthus is applying its expertise to advance its current pipeline to address significant unmet medical needs in oncology and autoimmune diseases.

Xanthus is headquartered in Cambridge, Massachusetts with an additional facility in Montreal, Quebec.

More information is available at

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 preclinical studies or clinical trials or warrant clinical 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 patents and patent applications owned or licensed by Xanthus, such as the patents and patent applications licensed from Johns Hopkins University, will protect the Company’s technology and prevent others from infringing it. Xanthus disclaims any intention or obligation to update any forward-looking statements.

Kari Watson, MacDougall Biomedical Communications, Inc. – or (508) 647- 0209
Lisa Terry, Xanthus Pharmaceuticals, Inc. – or (617) 225-0522, x 105