IDH1 and cholangiocarcinoma: Another preclinical study demonstrated that 2-HG produced as a result of IDH mutations suppresses homologous recombination and induces PARP (poly ADP ribose polymerase) inhibitor sensitivity (‘BRCAness’) [62], which led to a phase II trial with Olaparib in solid tumors, including CCA (ClinicalTrials.gov Identifier: NCT03212274).