Dexelvucitabine (DFC, Formerly Reverset)

DFC is an oral, once-daily cytidine nucleoside analog that we are evaluating for the treatment of HIV. In clinical and preclinical studies, DFC was active against most viruses containing drug-resistant mutations arising from the use of Viread, Epivir, Emtriva, Retrovir and others. DFC may potentially be used as a therapy for treatment-experienced individuals when taken in combination with other drugs, because it may be active against viruses containing the M184V, K65R, L74V and TAMs mutations that arise after prolonged therapy. While preclinical and early clinical studies showed DFC to be generally well-tolerated, more recent studies have shown DFC to be associated with increases in pancreatic enzymes.

We had been developing DFC in collaboration with Incyte Corporation until April 3, 2006, when Incyte announced its decision to discontinue its development of DFC after observing an increased incidence of grade 4 hyperlipasemia in the rollover portion of a Phase 2b clinical trial. Hyperlipasemia can be a marker of pancreatic inflammation. Incyte has terminated our license agreement and returned its rights related to DFC to us. We are analyzing the preclinical and clinical data on DFC generated by Incyte. Based on our preliminary review of the data provided to us, we believe further analysis of the merits of continuing to develop DFC is warranted.