Which option represents a chemotherapy regimen used for hairy cell leukemia?

• A. Methotrexate
• B. Rituximab
• C. Cisplatin
• D. 2CDA, cladribine

Answer: (D)

The key idea is that hairy cell leukemia responds best to purine analog chemotherapy. Cladribine, also known as 2CDA, is a classic purine analog used as a frontline single-agent treatment for this disease. It interferes with DNA synthesis, leading to rapid kill of hairy cell leukemia cells, and it has high remission rates with durable responses. Because of this, a regimen based on 2CDA, cladribine is the standard chemotherapy approach for hairy cell leukemia.

Other drugs listed don’t fit as the typical frontline cytotoxic regimen for this leukemia. Methotrexate is more common in other leukemias and lymphomas and isn’t a standard go-to for HCL. Cisplatin is a platinum agent used in solid tumors and some other cancers, not a standard HCL therapy. Rituximab is an anti-CD20 antibody used in various B-cell malignancies and can be helpful in HCL in certain contexts, but it’s not the traditional primary cytotoxic regimen for initial treatment.