ALNY has a goal of being a commercial company in the US. They clearly cannot bring a PCS product to market themselves, so internal investment in that program takes away from funding for rare disease programs that could actually be taken to NDA alone, such as TTR. I doubt they were really undecided a week, but chose to focus that CC on the scientific achievement (as they love to do, as business achievement have been a little lackluster in comparison), and wait for the guidance/goals PR and JP Morgan conference to talk business strategy.
EDIT - the FDA concerns around the PCSK9 target revealed by ISIS may have also cemented the decision not to invest a huge chunk of internal resources on the project if indications beyond hoFH or the like will be more costly that thought.
I haven't honestly looked much into the last couple 5x15 programs announcement (won't hit clinic for awhile still). But well before this Arrowhead cross-license, they had talked about using new delivery technology for some undisclosed # of these - but didn't specify which program or which technology (they have been publishing with numerous different technologies). The new agreement adds one more possibility, but doesn't really shed any new light.
MC3 appears to be pretty good, but clearly other new advances have outperformed it in preclinical models. They have the same issue as ISIS - for the same biological target they can go back and make better and better drugs - do you push ahead with the most advanced clinically, or start over and give up a couple years in exchange for potentially better drug. Diversifying away from the asset under dispute with TKMR may also be a factor, but hard to say at this point.
I was surprised that ALNY is only investing in 2 programs and plans to partner all others - seems very conservative with $260m cash. Maybe some other investment or settlement with TKMR is in the works for another chunk of the cash.
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