Just to add a little tidbit on this. Cambridge Antibody (now part of AstraZeneca) had a 5% royalty (there was along battle with Abbot on whether it should be 2 or 5% but they prevailed and got the higher rate). I hadn't kept up with it but did some digging and saw Royalty Pharma paid 700 million for the royalty. It seems they are going to get a great return on their investment. I followed them (Royalty Pharma) a bit waiting for them to go public (I believe they pulled at least 1 IPO) they have built a nice portfolio of biotech royalties (among the many they also have Neupogen/Neulasta and Rituxan royalties).