I don't think there was ever a chance that ALNY would develop PCS further without partnering. The key question on that CC was whether they needed to run more studies before partnering, and they clearly answered no. So I don't think "shelving" is the right term. I don't read much into the delivery agreement, except being confused (along with Dirk) as to why they didn't have rights to that platform already.
This move doesn't instill confidence in their second generation MC3 RNAi delivery considering they ended the year with 260 million in cash to invest along with all the built-up excitement over this drug. Is it the target? The expense of running trials in severe hypercholesterolemia? What bothers me is they chose to license another form of RNAi delivery from ARWR for their 5TH drug in the 5x15 initiative.
Have you taken a look at ARWR? Market cap is only ~$30M and they have the deal with ALNY for one early-stage drug that you referenced, along with recent deals they've inked with Shire and MRK. None of these deals were all that lucrative from a financial standpoint but that's not surprising given the size of the company and the fact that they're not in the best financial shape. Still seems to be a bit of an endorsement of their platform and at ~$30M market cap, it may not take much down the road to move the dial. They seem to have a diverse pipeline with programs spanning from obesity to cancer, among others, and also several different platform technologies (RNAi, homing peptides, etc.). See: http://www.arrowheadresearch.com/programs-overview . I at least have this name on my watchlist now. Dilution risk is probably one of the biggest risks here.