Saturday, July 18, 2009

HBV Collaboration between Benitec and Biomics Indicates Shift in DNA-directed RNAi Therapeutics towards Asia



My four years as a post-doc here in Stanford, during which my advisor Mark Kay served a term as the President of the American Society for Gene Therapy, taught me that drug development is as much about politics and perceptions as it is about the science.

This is particularly true when it comes to gene therapy and it is no surprise that despite pre-clinical data that, taken together, often surpassed that obtained with synthetic siRNAs, DNA-directed RNAi (ddRNAi) Therapeutics is struggling for funding in the corporate world. Targeted Genetics is a prominent example of a gene therapy company that despite much scientific (AAV-delivered RNAi data for Huntington’s Disease) and clinical progress (saving patients from blindness) is now facing bankruptcy. The reason? The regrettable death of a patient in a Targeted Genetics-sponsored clinical trial that has now been linked by experts to a immuno-suppressive monoclonal antibody the trial participant had been taking. The case was taken to the level of an NIH RAC (recombinant advisory committee) hearing, and synthetic oligonucleotide therapeutics companies are quite right in being scared that they, too, may be subject to RAC review in the future. I wonder what the outcome was from a recent meeting to discuss just this matter.

I am aware that gene therapy carries risks. Western society, however, needlessly deprives itself of potentially life-saving treatments when it chooses to suppress the entire field following isolated, albeit very unfortunate cases of adverse events linked to gene therapy. Then there are the so called ethical concerns of changing the human genome by introducing DNA into our cells as if sick patients had the luxury of worrying about this. By contrast, news of drug-related deaths in clinical trials of small molecules, many of which unlike the commonly used viral vectors have never been introduced into the human body, hardly ever reaches the wider public.

This week’s memorandum of understanding between Australia’s Benitec and China’s Biomics to collaborate on a DNA-directed RNAi therapeutic for chronic hepatitis B virus (HBV) infection may be a sign that the near to mid-term future for ddRNAi may instead lie in the economically vibrant parts of Asia. Here, practicality and an eagerness to adopt innovation means that gene therapies fall on much more fertile ground, including funding. Just last year, Benitec spin-off Tacere signed a similar deal with Japan’s Oncolys for the development of an ddRNAi Therapeutics for another viral disease of the liver, hepatitis C virus (HCV) infection.

Funding and access to R&D may have been financially struggling Benitec’s main motivation to reach out to Biomics. Also, Biomics provides Benitec with a foothold in a country that faces end-stage liver failures and hepatocellular carcinoma caused by chronic HBV that are of epidemic proportions. On the other hand, while Biomics, a biotech company with locations also in the US and that, with the help from some former Nastech employees, strives to transform itself from a mainly RNAi research-reagent company into an RNAi Therapeutics developer, certainly appears to enjoy better economic health and brings with it RNAi know-how, ideally it would have complemented Benitec ddRNAi patent estate and insights into shRNA design by providing an advanced delivery technology, maybe AAV. Although it is possible that they have such a technology, this is not apparent from the company's website which describes a range of delivery modalities that they are apparently working on.

For RNAi Therapeutics in general, Asia not only provides a growing market, but also an enormous R&D opportunity with many highly trained, detail-oriented chemists and increasingly also biologists to draw from. I am often surprised for example how many chemistry- and gene therapy-based publications on RNAi delivery come out of a country like Korea which is relatively minor in terms of biomedical research budgets, yet is little capitalized on due to lack of risk capital there. As for the IP situation in a country like China, I believe that once it becomes relevant, that is in maybe 7-15 years, China should be more aligned in this regard with the rest of the world and it would be a mistake not to make an effort of protecting your RNAi Therapeutics IP there, too.

HBV played a prominent role in the history of RNAi Therapeutics. Both synthetic (SNALP RNAi) and DNA-directed approaches proved successful in repressing HBV replication in mouse models. Since suppression of viral replication is a well-accepted measure for predicting HBV treatment success, RNAi Therapeutics should very well be able to complement current interferon-alpha and nucleoside analogue-based standard of care that result in unsatisfactory treatment success rates of only 20-30%. Due to the nature of the disease, however, it is unclear to me whether synthetic siRNAi or ddRNAi would be preferable. However, since treatment success by nucleoside replication inhibitors requires long-term treatment, probably due to the persistence of viral DNA in hepatocytes, a gene therapy approach has certainly theoretical justifications.

And finally, following Nucleonic’s fall and the situation around Targeted Genetics and Benitec, it is time for the entire RNAi Therapeutics field to think about creating a strong ddRNAi Therapeutic company before much of the IP is squandered. Consolidation of these efforts into a re-capitalized Benitec (disclosure: no current investments) may be one, although not the only option.

2 comments:

Enumerate said...

The "poster" project for ddRNA is the ARL work being conducted by Rossi/Zaia at the City of Hope.

This pilot, for a class of therapeutic modality, is reported to be going well.

Do you have a view on this, Dirk?

Dirk Haussecker said...

I also have hopes for the HIV program. We have to see, however, whether the choice of multiple U6 promoters was the right one. In principle, I believe that such an approach should work for HIV.

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