By Elliot Gulliver-Needham GSK shares have plunged this morning after a US court ruled on Friday that it would have to face trial by jury regarding the potential cancer-causing properties of its heartburn pharmaceutical Zantac. On Friday, a Delaware judge allowed almost 80,000 lawsuits against the pharmaceutical company to go ahead, arguing that the company’s expert witness opinion had lacked scientific support. The ruling could expose GSK to tens of billions of dollars in potential liabilities and legal redress. In 2022, Morgan Stanley estimated the potential liability for the industry at up …