GSK has agreed to pay up to $2.2 billion to settle most lawsuits in US state courts claiming that a discontinued version of the heartburn drug Zantac caused cancer, the company announced on Wednesday.

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 settles 93% of Zantac lawsuits with a $2.2 billion payout, easing investor concerns. However, doubts over its future growth persist as challenges with its drug pipeline remain.