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.