Sandbox: HCL therapy

Medical Therapy

• There is no curative treatment for hairy cell leukemia.
• The mainstay of therapy for hairy cell leukemia patients is chemotherapy.
• Asymptomatic hairy cell leukemia patients, with no indications for therapy, may be managed by observation and close follow-up.
• Indications to initiate medical therapy among patients with hairy cell leukemia include:

• The presence of systemic symptoms such as fever, night sweats, and significant weight loss
• The presence of subcostal abdominal discomfort due to splenomegaly
• A positive history of recurrent infections
• Hemoglobin concentration lower than 12 g/dl
• Platelets count lower than 100,000/mcl
• Absolute neutrophils count lower than 1000/mcl

• Pharmacological agents used for the treatment of hairy cell leukemia patients include:

• Cladribine
• Pentostatin
• Rituximab
• Interferon alpha
• Vemurafenib

First Line Therapy

• The preferred pharmacological agent used for the initial management of hairy cell leukemia could be either cladribine or pentostatin.
• Cladribine is administered by a single daily IV infusion for a period of 5-7 days.
• Pentostatin is administered by a single IV infusion every 2 weeks for a period of 3-6 months.
• Common side effects of such agents may include:

• Immune suppression
• Acute kidney failure
• Fatigue
• High fever

• Hairy cell leukemia patients who demonstrate a complete response following initial medical therapy should be followed-up with close observation for any signs of relapse.
• A complete response to medical therapy among patients with hairy cell leukemia is defined by:

• Resolution of the patient's symptoms
• The absence of splenomegaly on physical exam
• Recovery of the patients blood counts to the normal limits
• The absence of malignant leukemic cells on blood smear or bone marrow aspiration

Relapsed Therapy

• The optimal therapy for patients who relapse after a complete response depends on the duration of disease-free period following the initial medical therapy.
• Hairy cell leukemia patients who relapse after one year or more are be managed by the same initial purine analogue ± rituximab.
• Whereas hairy cell leukemia patients who relapse before a period of one year are managed by an alternative purine analogue ± rituximab.

Refractory Therapy

• Hairy cell leukemia patients who do not demonstrate a complete response to medical therapy could be further managed by any of the following agents:

• Rituximab alone
• Interferon alpha alone
• An alternate purine analogue ± rituximab

• Rituximab is administered by a single IV infusion every week for a period of 8 weeks.
• Interferon alpha is administered subcutaneously (3 million units) three times a week for a period of 12-18 months.
• The major side effect of rituximab treatment is serum sickness, whereas the major side effects of interferon alpha are flu-like symptoms and depression.
• Patients with progressive hairy cell leukemia who do not demonstrate a complete response to any of the aforementioned medical therapies should be managed with a BRAF kinase inhibitor, such as vemurafenib.