Benitec defends patents

Brisbane-based biotech Benitec Limited (ASX: BLT) has fired the first shot in what may become a major international battle to determine ownership of key patents to RNA interference (RNAi), which has been described as the most powerful tool for gene technology since the invention of the polymerase chain reaction (PCR) two decades ago.

Benitec announced today it has issued patent-infringement lawsuits in the US District Court in Delaware against three US companies for infringing its issued US Patent No 6,573,099, “Genetic Constructs for Delaying or Repressing the Expression of a Target gene”.

In a press release issued today, Benitec’s Chairman and CEO, John McKinley, said the lawsuits had been issued against Nucleonics Inc, Ambioin Inc and Genscript Corporation, for allegedly infringing Benitec’s patent on DNA-directed RNAi (ddRNAi) technique for silencing genes.

"We believe Benitec's patent estate is clear and represents an enforceable position in DNA-directed gene silencing,” said McKinley.

“We are committed to vigorously defending the rights that our patent estate confers and the licensees of our technology. There should be no doubt that we are prepared to do this and (that) we have the necessary resources, including patent insurance, to put this strategy into effect.

“Benitec will consider additional infringement actions as we deem appropriate in other jurisdictions."

Benitec’s ddRNAi technique can be used to selectively silence genes with gene constructs coding for messenger RNA molecules whose nucleic acid sequences are derived from the target gene.

The company’s patent also covers a technique for delayed silencing of genes, using promoters that can be activated on demand by an external signal.

The mRNAs produced by the construct spontaneously fold, by complementary base-pairing, into double-stranded “hairpin” molecules. These molecules trigger an inbuilt cellular mechanism that protects cells against viruses. By programming cells to destroy the normal, single-stranded mRNAs from the target gene, the ddRNAi construct eliminates the templates for protein synthesis, silencing the gene.

Benitec, whose researchers were the first to demonstrate RNAi gene-silencing in mammalian cells –including human cells, as well as in living mammals, holds the only issued patent on RNAi-mediated gene-silencing in mammalian cells.

McKinley says Benitec currently has seven issued patents in five jurisdictions, including the USA, UK and Australia, and another 60 pending patent applications in “advanced stages of prosecution” in 14 other countries.

The company owns core RNAi patents in partnership with CSIRO; Benitec holds exclusive rights to commercialise their human applications, while CSIRO’s rights relate to RNAi-mediated gene-silencing in plants.

Benitec researchers are investigating the potential therapeutic use of ddRNAi-mediated gene silencing for HIV-AIDS, hepatitis, cancer and central nervous-system disorders.