Xanthus Receives Orphan Drug Designation of Xanafide for the Treatment Of AML.

CAMBRIDGE, Mass. -- Xanthus Pharmaceuticals, Inc., a privately-held oncology drug development company, today announced that the FDA has granted Orphan Drug Designation to Xanafide([R]) (amonafide malate) for the treatment of acute myeloid leukemia (AML). Xanthus has recently completed enrollment of Xanafide([R]) in a Phase 2 trial in patients with secondary AML.

"We are pleased to receive Orphan Drug Designation for Xanafide," said Richard Dean, Ph.D., CEO of Xanthus. "No therapies are currently approved by the FDA for patients with secondary AML, a condition with a grim prognosis. This designation is part of Xanthus' plan to continue to progress its Xanafide([R]) program with the goal of giving patients with secondary AML a new treatment option."

The FDA grants Orphan Drug Designation to promising products that address diseases affecting fewer than 200,000 persons in the United States. If Xanafide receives FDA approval, this designation will entitle Xanthus to exclusive marketing rights for Xanafide([R]) for seven years following the NDA approval. Orphan Drug Designation provides companies with financial and regulatory incentives to pursue less common diseases.

About Xanafide([R]) and Secondary AML

Xanafide (amonafide malate) is an ATP-independent topoisomerase 2 inhibitor that the Company is developing for the treatment of secondary acute myeloid leukemia (AML) and related disorders. Secondary AML patients have had either antecedent myelodysplastic syndrome or prior exposure to leukemogenic therapy and represent a poor prognosis population. While de novo AML has approved treatments, no therapies are approved by FDA specifically for patients with secondary AML. In Phase 1 studies conducted in patients with poor-risk AML, amonafide hydrochloride, exhibited particularly promising clinical activity in patients with secondary AML. These results have stimulated the present program.

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 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.