The patent, entitled "Control of Gene Expression," is at the heart of this latest dispute. Nucleonics' request has cited 24 prior art publications showing the patent claims are invalid because they lack novelty and do not involve an inventive step.
In March 2004, Benitec filed an infringement suit in the United Statesagainst Nucleonics. The lawsuit alleged that three companies, Nucleonics, Inc., Ambion, Inc., and Genscript Corporation, were infringing upon issued US Patent No. 6,573,099, entitled "Genetic Constructs for Delaying or Repressing the Expression of a Target Gene."
In addition, Benitec has filed an opposition in Australia to the grant of a patent for the seminal invention in RNA interference, the Fire/Mello Patent, while failing to cite this important earlier work in its own applications around the world.
The Fire/Mello RNAi technology employs an expressed interfering RNA (eiRNA) approach, whereby scientists insert plasmid DNA coding for relevant double-stranded RNA (dsRNA) into targeted cells, letting the cells produce and deliver specific dsRNA sequences. Cellular mechanisms cleave the dsRNA into specifically encoded siRNAs(short interfering RNA), which silence the targeted genes.
Nucleonics' researchers have shown the ability of long or short dsRNA strands produced in this way to stably silence genes, including Hepatitis B and HIV, in relevant cell lines. Moreover, they have silenced multiple genes, as well as HBV replication, in adult mice without triggering an interferon response.
The plasmid DNA approach used by Nucleonics for expression of dsRNA hasdemonstrated human safety in over 500 patients to date, as part of research in the field of DNA-based vaccines. Nucleonics is initially directing this technology to the development of eiRNA therapeutics for Hepatitis B virus and Hepatitis C virus infections.
Robert Towarnicki, Nucleonics' chief executive officer said: "Nucleonics believes the Benitec intellectual property portfolio is fatally flawed, not only in Australia, but in the United States and elsewhere as well."
"We intend to vigorously defend our right to continue to develop needed therapeutics for chronic viral diseases such as Hepatitis B and Hepatitis C around the world."