Amgen's poker face

SEC filings posted last week detailing the negotiations between Amgen Inc. and Onyx Pharmaceuticals Inc. show that Amgen managed to shave more than $400 million off the final price based on interim Phase III data for multiple myeloma drug Kyprolis carfilzomib.

The data from the FOCUS trial, which emerged in late July, also scared off the only other offer Onyx was still seriously entertaining...