GSK agreed to pay more than $2 billion to settle almost all remaining liability cases in the U.S. over allegations its discontinued heartburn medicine Zantac causes cancer.

GSK Plc shares surged after the UK pharma company agreed to pay as much as $2.2 billion to resolve about 80,000 US court cases alleging that its old reflux medication Zantac was contaminated with a suspected carcinogen.

GSK shares jumped as much as 6.5% on Thursday after the British drugmaker struck a $2.2 billion settlement over U.S. lawsuits that alleged its discontinued heartburn drug Zantac caused cancer.