Vestar Inc. announced Wednesday that it has sued LiposomeTechnology Inc. (LTI) over a patent just issued to LTI on amethod for making liposome-entrapped amphotericin B.
LTI (NASDAQ:LTIZ) of Menlo Park, Calif., announced Tuesdaythat it had been awarded U.S. patent No. 5,180,713, claiming amethod of preparing a stable liposome-entrapped amphotericinB drug product.
Vestar (NASDAQ:VSTR) of San Dimas, Calif., responded in arelease, also on Tuesday, that "the methodology described inthis patent does not appear to be relevant to Vestar's productAmBisome." Yet Vestar is now asking the Delaware federalcourt to declare that LTI's patent is invalid and is not infringedby Vestar's product AmBisome.
LTI has not yet responded to Vestar's announcement. PeterLeigh, LTI's chief financial officer, told BioWorld that thecompany can't respond because "LTI hasn't been served, andwe haven't seen the complaint."
LTI believes that the method claimed in the patent providesthe optimal means of preserving the particle size ofamphotericin B-containing liposomes during storage, a key tocommercializing such a product. LTI scientists developed themethod to address the problem of particle size growth duringstorage.
Vestar stated Tuesday that since its liposomal formulation ofamphotericin B, AmBisome, doesn't change size beforelyophilization (freeze-drying) or after reconstitution, it doesn'tneed "any process to prevent size changes."
And LTI isn't even using the newly patented method toproduce its amphotericin B product, Amphocil. But LTI believesthat the patent "may pose a barrier to competitors making orselling a liposome-entrapped amphotericin B formulation in theU.S." Vestar "is the only company making a liposomalamphotericin B in the U.S. on a manufacturing basis," accordingto a company source.
Vestar is also in litigation over liposomal formulations ofamphotericin B with The Liposome Company Inc. (TLC) ofPrinceton, N.J. TLC (NASDAQ:LIPO) sued Vestar last June forinfringing its U.S. patent, No. 4,229,360, regarding thelyophilization of liposomes. Vestar turned around in July andcountersued TLC, stating that the patent was invalid because"the invention is not novel and is not properly described in thepatent." Vestar denied it was infringing TLC's patent, and askedthe U.S. district court to declare TLC's patent to beunenforceable. The trial is set for this November.
Vestar's countersuit with LTI is based on the same type of"standard jockeying" it used with TLC, according to Alex Zisson,an analyst with Hambrecht & Quist Inc. But whatever theultimate results of the patent imbroglios, "it's going to bedifficult to kick Vestar's product out of the market if there's nosimilar drug approved," Zisson told BioWorld.
Vestar's AmBisome is being sold in at least 21 Europeancountries, TLC plans to file an application for its ABLC drug bythe fourth quarter of this year, and LTI just this month filed itsfirst PLA on Amphocil -- in the United Kingdom.
The Liposome Company's stock closed Wednesday at $11, down13 cents a share; Liposome Technology's stock was off 25 centsa share to $9.25; and Vestar dropped 50 cents a share, closingat $13.
-- Jennifer Van Brunt Senior Editor
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