Valentis Inc announced that its wholly-owned subsidiary, PolyMASC Pharmaceuticals Plc, has received a favorable ruling from the Japanese Patent Office in regard to patent invalidation proceedings brought by Alza Corporation, a unit of Johnson & Johnson. This proceeding was the final level of review within the Japanese Patent Office.

The ruling received today from the Trial Board of the Japanese Patent Office dismissed the Demand for Invalidation of claim 5 of Japanese Patent No. 2948246, thereby maintaining the validity of the claim. Claim 5, the only claim at issue in the proceedings, covers a method for increasing the in vivo circulation lifetime of liposomes by pegylation. Pegylation refers to the covalent attachment of PEG (polyethylene glycol) moieties to the liposome surface.

The Japanese patent at issue in these proceedings is the counterpart to U.S. Patent Number 6,132,763 and European Patent Nos. EP572,049B1 and EP445,131B1. PolyMASC has asserted patent infringement in both the U.S and Germany based on Alza's manufacturing and selling of Doxil and Caelyx, PEGylated-liposome products encapsulating the drug doxorubicin. Doxil is currently approved and marketed in the United States for Kaposi's sarcoma and refractory ovarian cancer by Ortho Biotech, a subsidiary in the Johnson & Johnson family of companies. The same product, Caelyx, is approved and marketed in Europe for the same indications and breast cancer by Schering Plough.

PolyMASC previously announced, in October 2000, that the Opposition Division of the Japanese Patent Office had found in favor of PolyMASC's patent in a prior opposition proceeding. In response to that decision, Alza filed a Demand for Invalidation Trial, which was, essentially, an appeal of the decision by the Opposition Division. The ruling received today dismisses Alza's demand for invalidation.