The FDA has approved Arnuity Ellipta for asthma.
Amgen now hopes a separate study will be enough to support the drug's advancement to a second-line therapy, but the lackluster results may impinge on its EU filing schedule.
GlaxoSmithKline, Actelion, Sanofi and Roche are said to be among a host of suitors.
Layoffs are reported to be in the offing.
Blood-cancer drug Kyprolis outperformed standard treatment in a late-stage trial testing the drug in patients with multiple myeloma, said Amgen.
Sanofi and partner Regeneron attached a $67.5-million priority review voucher to their experimental cholesterol drug alirocumab, making for a tighter race with Amgen.
The meningitis and encephalitis medications earned a combined $300 million last year.
AstraZeneca has made an $875-million move to beef up its respiratory pipeline by making Almirall's lineup its own.
The majority of the layoffs will be in the US.
Patent losses and lost co-promotion agreements put a dent in sales.