It's Affymax by the way not Affymetrics. Amgn will start to loose market share to affymax that why they are buying other pharmas cause they know what is coming and they cant buy affymax due to anti trust laws.
Not sure anti-trust laws would stop them. I am always surprised at what they let merge. But Takeda already owns half this drug, so at best they could get 1/2. It will have the same safety concerns as epo because it is on mechanism. Lastly, Amgen secured a contract with 50% of the dialysis centers for 7 yrs in one case and the length was not clear in the other case. So those dialysis centers are committed to Amgen even after epo comes off patent.