The U.S.Food and Drug Administration (FDA) has granted pre-market approval to Thermo Fisher Scientific's Oncomine Dx Target Test as a companion diagnostic (CDx) to identify patients with isocitrate dehydrogenase-1 (IDH1) mutated cholangiocarcinoma (CCA) who may be candidates for Servier Pharmaceuticals' TIBSOVO® (ivosidenib tablets). TIBSOVO is an IDH1 inhibitor that is approved for the treatment of adult patients with previously treated, locally advanced or metastatic CCA with an IDH1 mutation as detected by an FDA-approved test. CCA is a rare, aggressive cancer of the bile ducts within and outside of the liver. IDH1 mutations occur in up to 20% of CCA cases in the Unites States and are not associated with prognosis.1 Prior to the approval of TIBSOVO on August 25, 2021, there were no approved targeted therapies for IDH1-mutated cholangiocarcinoma and limited chemotherapy options are available in the advanced setting. TIBSOVO is also approved in the U.S. as monotherapy for the treatment of adults with IDH1-mutated relapsed or refractory acute myeloid leukemia (AML) and for adults with newly diagnosed IDH1-mutated AML who are =75 years old or who have comorbidities that preclude the use of intensive induction chemotherapy. The approval of TIBSOVO in previously treated IDH1-mutated CCA is supported by data from the ClarIDHy study, the first and only randomized Phase 3 trial for previously treated IDH1-mutated CCA.