NMS-173 induced stronger and more durable efficacy than ivosidenib in the HCCC-9810 IDH1 mutant cholangiocarcinoma xenograft model and increased the survival of mice bearing the LEXFAM2734 IDH1 mutant PDX AML line, with a better disease control compared to ivosidenib. NMS-173 was very well tolerated upon repeated administration in different species with a wide therapeutic window in non-GLP and GLP tox studies.