BENITEC GRANTED FIRST U.S. AND U.K. PATENTS FOR DNA DIRECTED GENE SILENCING
Patents Underscore Benitec's Leading RNAi Position

5 June, 2003

QUEENSLAND, Australia (June 5th 2003) Benitec Ltd. (ASX: BLT), the first company to demonstrate RNA interference (RNAi) in human cells, announced today the grant of its core technology patents in the United States and the United Kingdom. These patents, with priority dating to1998, describe a revolutionary method for silencing any gene in any cell using DNA directed RNA interference (ddRNAi). U.S. Patent 6,573,099 is entitled "Genetic constructs for delaying or repressing the expression of a target gene" and U.K. Patent 2353282 is entitled "Control of gene expression". Both patents contain world first claims that describe the effect of RNAi in human cells and the DNA constructs which trigger RNAi. The patents were jointly granted to Benitec and The State of Queensland, Australia and Benitec holds exclusive worldwide rights to both patents under a partnership agreement with The State of Queensland.

"These broad patents confirm Benitec as a pioneer in the effective application of RNAi to humans and the leader in ddRNAi technology," stated John McKinley, Chairman and Chief Executive Officer of Benitec, Ltd. "We will now leverage our dominant IP position to secure further commercialization opportunities, add to our licensing partners and expand our efforts to develop ddRNAi targets for drug development."

"RNAi is the simplest and most precise method of gene silencing and ddRNAi is the most versatile method of triggering RNAi in human cells," stated Ken Reed, Director of Research & Technology with Benitec. "In contrast to RNAi induction using double-stranded RNA, ddRNAi does not provoke the natural interferon response in cells. Critical to the biopharma industry, ddRNAi can also manipulate gene silencing for either transient or permanent effect, and can be used to reduce gene expression or silence it completely. It also has more versatility with respect to delivery vehicles, further increasing options for development of therapeutics. As a bonus, manufacturing costs are significantly less."

ABOUT ddRNAi
DNA directed RNAi (ddRNAi) is a method to trigger the natural gene suppression process called RNAi that operates by destroying messenger RNA (mRNA), the courier that delivers instructions to the ribosomes within the cell to manufacture the proteins coded for by DNA. By introducing a DNA construct into a cell, Benitec's ddRNAi technology triggers the production of double stranded (dsRNA), which is then cleaved into small interfering RNA (siRNA) as part of the RNAi process, resulting in the destruction of the target mRNA and knocking-down or silencing the expression of the target gene.

An alternate approach to triggering RNAi currently under development uses siRNA to directly induce the RNAi process. While both approaches trigger RNAi, Benitec's ddRNAi approach does not activate the cell's interferon (stress) response. The interferon response is a natural cellular defense mechanism that responds to double-stranded RNA, as in a virus, by shutting down many normal functions.

Benitec's ddRNAi provides the ability to control the silencing effect so that it either knocks down or completely silences the target gene. Control can also be exerted to make the silencing effect transient or permanent. siRNA technologies under development are only capable of transient silencing and are to an extent dependent on how much can enter a cell.

ddRNAi can also be used with a range of efficient delivery options not available to the siRNA approach, providing additional versatility for therapeutics development. These qualities also make ddRNAi well suited to high throughput functional genomics and target validation, and provide added versatility when developing RNAi targets for drug development.

Benitec Limited, based in Queensland, Australia, is the leader in the field of gene silencing technology based on DNA directed RNA interference (ddRNAi). Benitec pioneered ddRNAi and was the first company to demonstrate RNAi in human cells. With granted patents in the United States, the United Kingdom, Australia, South Africa and Singapore, and patent applications pending in Europe, Japan, and 12 other jurisdictions covering its ddRNAi technology, Benitec holds a dominant international intellectual property position. Benitec has embarked on an aggressive strategy to leverage its leadership position and license its technology along the entire chain of the drug discovery and development process, and is applying the technology to develop its own ddRNAi targets for drug development. As previously announced on 8th April, Benitec has granted Promega Corporation (Madison, WI) its first worldwide exclusive license (with rights to sub-license) to develop, sell and distribute ddRNAi products based upon Benitec's proprietary technology.

This press release contains forward-looking statements which reflect Benitec's current expectation regarding future events. Forward-looking statements involve risks and uncertainties. Actual events could differ materially from those projected herein and depend on a number of factors including the success of Benitec's research strategy, the application of the discoveries made therein, the successful and timely completion of clinical studies and the uncertainties related to the regulatory process.