After Medarex (MEDX +89%) fetched a healthy premium from Bristol-Myers Squibb (BMY +3.1%), investors have begun looking at similar companies to see who's next up for bids: Regeneron Pharmaceuticals (REGN +8.8%)? Seattle Genetics (SGEN +5.6%)? Alexion (ALXN +7.6%)? Allos Therapeutics (ALTH +6.9%)? Celldex Therapeutics (CLDX +6.7%)? Dendreon (DNDN +6.6%)?