The drugmaker is offering to pay the biotech a royalty so it can sell its Mircera drug in the US, according to reports citing documents filed in Boston. Why does Roche need to pay Amgen? Although Roche won FDA approval to sell Mircera, the drugmaker last October lost a lawsuit in which a jury decided the anemia drug violated Amgen patents.

So Roche is offering to pay Amgen a royalty that is roughly double what Johnson & Johnson pays Amgen to market Procrit. Specifically, Roche is willing to sell Mircera for about 5 percent less than what Amgen charges for its Aranesp medication and pay a royalty of 20 percent on US net sales for the duration of Amgen’s patents. Roche says that US District Court Judge William Young asked the drugmaker to make a proposal.

“It is projected that under this current proposal that the savings to Medicare and the US. Government and taxpayers for reimbursement for treatments with these pharmaceuticals will be substantial, and easily in the billions of dollars,” Roche wrote in its court filing, according to the paper.

“Is this a reality that’s going to play out? Probably a small chance,” William Burns, head of Roche’s pharmaceutical unit, tells The Wall Street Journal. “It’s now up to Judge Young to take a holistic view of all the evidence he’s seen and make his judgment.”

As of now, Amgen is playing hard to get. “As Amgen demonstrated at the injunction hearing, Roche’s product and marketing proposals confer no clinical benefit, serve no public interest, and would actually increase the cost of treatment to Medicare, especially in the short term,” Amgen says in a statement e-mailed to us. “Roche’s belated royalty proposal is grossly inadequate to compensate Amgen for Roche’s infringement and lacks any merit.”

In its court filing, Roche reportedly indicated it would begin taking steps to market Mircera in the US if the judge doesn’t resolve an injunction at month’s end, whan a hearing is to take place. “Roche cannot continue to stay off the market voluntarily if a decision on the outstanding issues, particularly on the permanent injunction, is not to be expected shortly,” the company said in the memo.