AstraZeneca’s rare disease group, Alexion, and Roche’s Chugai Pharmaceutical unit are putting down their weapons.

The two have reached a settlement agreement related to the intellectual rights of Ultomiris (ravulizumab). Both companies will withdraw the lawsuits filed in both the U.S. and Japan, and as a part of their deal, AstraZeneca will pay Chugai $775M in the second quarter, with no other payments or royalties necessary beyond that.

Alexion and Chugai had been in patent war since 2016 when Alexion challenged Chugai’s patents in Europe and Japan. Later in 2018, Chugai filed a lawsuit against Alexion in both Japan and the U.S. AstraZeneca inherited the disagreements when it purchased Alexion last year. The buyout was AstraZeneca’s largest deal to date, coming in at $39B.

Ultomiris works by inhibiting a protein found that triggers an immune reaction called a complement cascade. When this cascade is overly activated, the body’s sensitivity to threat becomes compromised and the immune system begins attacking healthy cells.

The drug is currently approved in the U.S. to treat two rare conditions, paroxysmal nocturnal hemoglobinuria (PNH), and hemolytic uremic syndrome (aHUS), which causes anemia and blood clots.