Ironwood Pharmaceuticals Inc. is kicking off twin phase III trials of a specially formulated bile acid sequestrant developed to help people with uncontrolled gastroesophageal reflux disease (GERD) minimize symptoms of the ailment, such as heartburn. The trials will test IW-3718, the lead non-guanylate cyclase-C candidate. If successful, they would provide the evidence needed to seek approval for the medicine, which would be marketed as an adjunct therapy to standard-of-care proton pump inhibitors (PPIs).