Orbital myeloid sarcoma treated with low-dose venetoclax and a potent cytochrome P450 inhibitor

Case report We report the first case of orbital myeloid sarcoma that was successfully treated with a standard venetoclax dose of 25%. A 38-year-old man with acute myeloid leukemia (AML) post-haplo-hematopoietic stem cell transplantation (HSCT) presented with a nine-month history of progressive right proptosis and a visual acuity deficit. The patient was treated with venetoclax (100 mg orally on days 1–28), cytarabine (40 mg subcutaneously, days 1–10), and itraconazole (100 mg twice daily orally on days 1–28). Management and outcome The present case report shows that using cytochrome P450 (CYP) inhibitors is a helpful strategy to reduce the cost of expensive treatments. Discussion There are limited data on the use of CYP inhibitors as a strategy to reduce the costs of expensive drugs (i.e. venetoclax). This approach has some advantages over standard dose venetoclax (400 mg/day) such as significantly reduced costs (which is relevant for patients in low-income countries). In this case, we used itraconazole—a potent CYP3A4 inhibitor—which can theoretically reduce the dose to 100 mg/day without losing serum therapeutic concentrations.