Saturday, August 9, 2008

RNAa- Alnylam Continues to Gobble Up Fundamental RNAi-related IP

Earlier this week, Alnylam announced the consolidation of intellectual property related to RNA activation (RNAa). RNAa is a method of sequence-specifically activating genes by the introduction of cognate double-stranded small RNAs. It is similar to siRNAs, but in this case the dsRNA corresponds to certain gene promoter elements instead of the mRNA in the case of siRNAs. In addition to once again positioning Alnylam up to be the gate-keeper of a potentially new class of small RNA therapeutics that harness natural gene regulatory mechanisms, as RNAa touches upon RNAi biology, this development has also to be seen as further cementing Alnylam’s grip on fundamental RNAi and siRNA IP thereby creating immediate value.

RNAa quietly emerged over the last 3-4 years in the shadows of the RNAi revolution. When it was discovered that RNAi-related mechanisms function in transcriptional gene silencing (TGS) in fission yeast (explanation: in TGS, siRNAs mediate chromatin modifications that prevent a gene to be transcribed in the first place, rather than being targeted for degradation after having been transcribed as in RNAi), researchers around the world, including myself, started to look at whether a similar mechanism operated in mammalian cells. While initially met with some skepticism and controversy, the overwhelming evidence now strongly supports that TGS indeed exists in mammalian cells.

One branch of TGS research introduced siRNAs targeted to gene promoters with the aim of silencing that gene by recruiting chromatin silencing machinery to the targeted DNA elements. As was subsequently reported, in some cases they do. But to the surprise of many, some of these siRNAs had just the opposite effect, namely they activated expression from the corresponding gene. As detailed in Alnylam's press release, this does not appear to be an isolated effect, but was shown by a handful of labs to be applicable to a number of genes looked at.

While the mechanism of action of these small RNAs, referred to as ‘antigene RNAs’ (agRNAs) to distinguish them from their better known cousin, remains spotty, it appears that low-level non-coding transcription around the targeted promoters are recognized by the agRNA in a process that involves Argonaute proteins and leads to activating chromatin modifications. In addition to sharing with RNAi the Argonaute proteins, good agRNAs appear to follow similar design rules as siRNAs: 19-21 base-pair dsRNAs with seed-match dependency. 3' overhangs have also been used, although the utility of this structural feature has not been explicitly demonstrated. Consistent with an epigenetic mechanism, the effect can be quite long-lasting (~10-14 days of gene activation following agRNA introduction in tissue culture cells, and likely to be even longer lasting in primary cells).

Moreover, agRNAs appear to tap into a natural gene regulatory pathway as endogenous small dsRNAs had previously been shown to switch on the activity of cognate promoters. MicroRNAs, some of which are known to be localized to the nucleus, have also been implicated here.

From Alnylam’s press release and the Q2 '08 conference call, the consolidation of RNAa IP that is based on the first reports of RNAa in the literature, was explained as representing yet another small RNA-related business opportunity for the company, similar to how it views microRNAs. Due to the early nature of RNAa, it is likely that while Alnylam will pay for IP-related expenses, it will be the academic labs that licensed the technology that will conduct much of the initial research. It also remains to be seen when we will see a Regulus-like RNAa spin-off.

I would argue that if RNAa and RNAi had little overlap, Alnylam would have been better advised to let others invest instead of diverting focus and resources from RNAi Therapeutics that should yield a much higher return on investment. RNAa is still at an comparably early development stage, and the number of therapeutic opportunities should be much restricted compared to RNAi Therapeutics. Initially, I would expect the re-activation of tumor-suppressor genes for cancer therapy to be the major attraction.

One factor, however, that could have tipped the economic scales in favor of an investment in RNAa is the fact that RNAa and RNAi seem to intersect both with respect to biology and technology. One paper suggests that Argonaute 2, the Slicer of RNAi, is indispensable for RNAa. As the functions of the 4 human Argonautes slowly emerge from the research labs around the world, this adds to the notion that siRNAs, once introduced into cells, could function in more than one way in regulating gene expression. As such, RNAa broadens the methods of using siRNA structures protected by Alnylam IP.

This synergy in IP may also at least partly explain why Alnylam and not ISIS Pharmaceuticals, its Regulus partner, embraced RNAa in such a comprehensive manner. This is despite of ISIS’ contribution of research reagents to one of the underlying papers and a RNA therapeutics business strategy that has been broader than that of Alnylam’s. Still, with Alnylam securing fundamental IP related to harnessing natural small RNA gene regulatory pathways and ISIS in possession of an impressive and complementary nucleic acid IP portfolio and a near-term drug opportunity in mipomersen, I would not count out a future involvement of the Carlsbad company. I also wonder at which point it may even make sense to just combine the two companies.

PS: Should RNAa turn out to be widely applicable and if RNAi Therapeutics history is any guide, odds are that competing companies will come up with Atu- and RXagRNA designs that vary slightly in structure, claiming to have superior activity and enjoying freedom-to-operate. Nucleonics and MDRNA, however, should serve as stark reminders that this may not be the best strategy of creating shareholder value. The so very demonstrative nature of the RNAa IP consolidation this week should serve as a useful reference against which competing claims will have to be measured.

8 comments:

Anonymous said...

"Initially, I would expect the re-activation of tumor-suppressor genes for cancer therapy to be the major attraction."

From a delivery perspective, SNALP would appear well suited with its ability to deliver into tumor tissue.

Dirk, how about a combined therapeutic, e.g., SNALP carrying both RNAi-inducing siRNA and RNAa-inducing siRNA into tumor tissue? Perhaps this could profit from the substantial research to date by ALNY and TKM in connection with their SNALP based VSP01 and PLK programs, respectively.

Martin

Dirk Haussecker said...

Martin- Good thought. ALN-VSP01 is actually a SNALP RNAi Therapeutic comprising two different siRNAs, and a agRNA looks chemically quite similar, if not identical to an siRNA. It is then certainly possible to also design an SNALP RNA therapeutic having one siRNA knocking down an oncogene, while the RNAa increases tumor-suppressor gene activity that had been silenced by epigenetic mechanism.
Dirk.

Anonymous said...

" I also wonder at which point it may even make sense to just combine the two companies. " ....

Dirk, thanks again for the blog. In reference to your analysis about combining the two companies, are you suggesting a combination between Alnylam and Isis for RNAa similar to the Regulus MicroRNA transaction. Or were you suggesting a merger between the two whole companies, Alnylam and ISIS. Could you elaborate on possible synergies between the two? (IP, in the lab, business development) Thanks and keep up the good work.

James

Dirk Haussecker said...

James- The importance of the ISIS IP with regards to RNAa is more similar to its importance for RNAi than for microRNAs, and probably even less so since RNAa is not about gene silencing. By contrast, ISIS IP is much more important for the development of microRNA antagonists, hence its equal participation in Regulus. No- I meant a full-blown merger. On the surface, it could make sense to combine ISIS' chemistry know-how, IP and near-term pipeline opportunities with Alnylam's gate-keeping position in a biology that I believe is crowding out traditional antisense knockdown. A combination of the powerhouses of the past, present, and future of RNA therapeutics. Both have sound balance sheets and management teams seem to get along surprisingly well.

Anonymous said...

Carlsbad in the winter and Cambridge in the summer? Sounds good to me.


ISIS\Alnylam combined would be interesting. The two companies are of a comparable size and innovative mindset so you would not have the bureaucratic concerns that go along with most biotech mergers. If 1 + 1 = 2 then you would have a market cap of just over 3 billion (ALNY at 1.43b and ISIS at 1.70b) with the combined companies. Seeing as Imclone is going to be sold for over 5 billion, I think 3 billion seems rather cheap.

And you are correct, combining ISIS' near term prospects with Alnylam's developing in-house pipeline and future co-development rights with Big Pharma would be nothing short of spectacular in the "shots on goal" it would create over the next decade. And I did not even mention Regulus, RNAa, Vaccines…

- James

Anonymous said...

ALNY/ISIS Merger? I am a bit sceptical as I am not convinced of the added value for ALNY and keep in mind that mergers are a major headache that take toll on management time.

However, if ALNY were to merge with anyone, ISIS would be the obvious choice. If they do, they should think big and throw in Tekmira as well.

Here are few interesting pieces of info:

- Stan Crooke is over sixty.
- Jonas (seen by some as Stan Crooke's successor) resigned recently and unexepctedly. No press release, no explanation of the departure.

Any dots here to connect?

Martin

GS said...

Good article & comments as always.

Dirk, is there evidence to date suggesting that RNAa is amplified again, like RNAi?

GS said...

Good article & comments as always.

Dirk, is there evidence to date suggesting that RNAa is amplified again, like RNAi?

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