Amgen has been trying since 2015 to protect its PCSK9 cholesterol drug Repatha by keeping Sanofi and Regeneron’s rival Praluent off the market, even going as far as to ask the U.S. Supreme Court to review an ongoing patent fight.

But that attempt fell short this week as SCOTUS refused to hear the company's appeal of a 2017 court decision allowing Sanofi and Regeneron to continue selling its head-to-head rival.

Amgen isn’t giving up the fight, though. The company is prepping for a new patent trial starting in Delaware federal court next month. And it’s responding to long-standing criticism of the high cost of PCSK9 drugs, which hit the market in 2015 at list prices of about $14,000 a year.

Amgen had already brought the price of the biweekly version of Repatha down to $5,850 per year before discounts and rebates, and late Monday it said it would lower cost of the monthly injectable dose to that same level.

When Amgen rolled out the first price break in October, Executive Vice President of R&D David Reese told FiercePharma there had been "intense frustration" over the lack of pickup of the drug. A real-world outcomes study showed that Repatha cut heart attack risks by 27%, strokes by 21% and coronary revascularizations by 22%, but payers still put up high barriers to access, he said.

CEO Bob Bradway echoed those sentiments this week and said he hoped the latest round of price cuts would free up access to Repatha. "This is a therapy, a biologic, specifically designed to lower the bad cholesterol, LDL, which it does on average by 63%," he said in an interview on CNBC’s Mad Money. "We found too many patients were prescribed this therapy but were struggling to pay for it at the pharmacy counter," and reaction to the price cut has been positive so far, he added.

But whether the newly lowered price will boost Repatha sales is an open question. Analysts once predicted PCSK9 drugs would be blockbusters. Sales of the drug did jump 35% year over year in the third quarter of 2018, but that only amounted to $120 million in sales, as the net selling price took a hit from discounts and rebates offered to payers.

And now that Amgen won’t be getting any help from SCOTUS in the ongoing patent battle, it will have to continue to vie for market share against Sanofi and Regeneron’s Praluent. Amgen’s Bradway saidduring the J.P. Morgan Healthcare Conference in San Francisco this week that Repatha holds 64% of the market.

The legal wrangling between the three companies dates back to 2014, when Amgen first sued Sanofi and Regeneron claiming patent infringement. In 2016, a jury sided with Amgen, granting an injunction that would have kept Praluent off the market. But a Federal Circuit court threw out the injunction.

In its appeal to the Supreme Court, Amgen argued that the lower court had improperly created its own standards that were at odds with the Patent Act. Those included "sub-tests" that would require inventors to prove they possessed their inventions as of the date they filed for the patents. Amgen argued that under such standards, inventors would have no way of predicting which disclosures would be enough to protect their intellectual property.

A spokesperson for Sanofi said in an email to FiercePharma that the company and partner Regeneron were pleased with the Supreme Court’s decision not to take up Amgen’s appeal. "We are confident that the law and the facts support our positions," she said.

Amgen, for its part, isn’t prepared to concede defeat anytime soon. "We believe in the validity of our PCSK9 antibody patents," a spokesperson said in a statement, "and are preparing to return to the trial court to retry the remaining issues in the case." That trial is scheduled to begin Feb. 19.