Hairy cell leukemia (HCL) treatment

Hairy cell leukemia (HCL) is usually slow growing, and not all newly diagnosed patients with HCL require immediate treatment. It's important that your doctor is experienced in treating patients with HCL or works in consultation with an HCL specialist. This type of specialist is called a hematologist-oncologist. 

Learn more about communicating with your blood care specialist or find a list of suggested questions to ask your healthcare providers. 

Types of treatment for HCL 

A patient has two options for treatment: standard of care or a clinical trial. It is important to talk to the healthcare team about the best treatment option. 

HCL is usually slow growing, and not all newly diagnosed patients with HCL require immediate treatment. For approximately 10 percent of patients, if they have stable blood counts and no symptoms at the time of diagnosis, the treatment may be the “watch-and-wait” approach. Watch and wait means treatment is delayed until signs and symptoms of the disease appear or progress. Some patients with HCL live for many years without any symptoms and without receiving any treatment. Frequent monitoring, including blood testing, is necessary so that treatment can be started if the disease begins to advance.  

Learn more about watch and wait. 

Patients should begin treatment if they have low blood cell counts (low red blood cell, white blood cell, or platelet counts). They should also begin treatment if they exhibit symptoms, including unexplained weight loss, recurrent infections, and/or physical discomfort due to an enlarged spleen and/or liver.  

Most often, initial treatment for HCL involves a type of chemotherapy called a purine analog. There are two purine analogs approved by the Food and Drug Administration (FDA) for HCL:  

• Cladribine (Leustatin®)
• Pentostatin (Nipent™)  

These drugs appear to be equally effective in achieving durable remission. The choice between the two drugs is usually determined by doctor preference or patient convenience.  

Cladribine and pentostatin both induce durable complete responses in approximately 80 to 85 percent of patients. Most patients who receive cladribine or pentostatin as first-line treatment experience a complete remission that can last for several years. A complete remission means:  

• Normalization of blood counts
• Disappearance of hairy leukemia cells from the blood and bone marrow
• Reduction in size of the spleen (determined by physical examination)
• Absence of disease symptoms 

For information about the drugs listed on this page, visit our cancer drug listing.  

It is important for patients and their medical teams to discuss all treatment options, including treatments being studied in clinical trials. 

Learn more about clinical trials. 

Get free clinical trial support! Visit our Clinical Trial Support Center (CTSC).

Connect with registered nurses with expertise in blood cancers who can personally assist you or your caregiver through each step of the clinical trial process. 

HCL treatment side effects 

Neutropenia is a condition in which there is a lower-than-normal number of neutrophils, a type of white blood cell that helps fight infections. For HCL patients with neutropenia, doctors may prescribe a broad-spectrum antibiotic to prevent infections. Sometimes treatment may cause severe neutropenic fever, and if that happens, the doctor may prescribe a granulocyte colony-stimulating factor (G-CSF), a treatment that helps the body produce more white blood cells.

Infection is the most frequent cause of death in HCL patients. Prior to treatment, patients often already have low white blood cell counts, which puts them at risk for infection. Then, after they begin treatment, they are at greater risk for infection because both cladribine and pentostatin are “immunosuppressive,” which means they further lower white blood cell counts. This reduces the body’s ability to fight infections and other diseases and places patients at higher risk of developing a life-threatening illness.

Doctors should educate patients about preventing infections. It is also important for patients to contact their medical team if they have any signs or symptoms of an infection, such as fever or rash.

Learn more about HCL treatment side effects and how to manage them.

Treatment results  

Treatment results and outcomes vary among patients. Newer treatment therapies, progress in stem cell transplantation, better supportive care, and studies of new drugs in clinical trials are all contributing to improved outcomes and quality of life for people diagnosed with blood cancers. 

Relapsed and refractory HCL  

Some patients do not respond to treatment at all (called “refractory” disease), and others respond at first, but over time their disease comes back (called a “relapse"). These patients require additional treatment. 

Refractory HCL 

Patients with refractory HCL should be encouraged to consider treatment in a clinical trial, if one is available. Other options for patients with refractory disease include: 

• A different purine analog with or without rituximab (Rituxan®)
• Rituximab (if the patient is unable to receive purine analog therapy)
• Interferon alpha (Intron® A)

Relapsed HCL 

Treatment options for patients who have relapsed disease after remission depend on the quality and duration of the first remission.  

• Patients who relapse after a long remission of over five years may be re-treated with the same initial purine analog therapy
• Patients with remissions that have lasted between two and five years may benefit from additional treatment with the same purine analog, possibly combined with rituximab or a clinical trial
• If the remission lasted for less than two years, options include the following:
• Treatment with alternative purine analog with rituximab
• Rituximab (if the patient is unable to receive a purine analog)
• Diagnostic testing to reconfirm HCL diagnosis. If HCL is confirmed, treatment with alternative therapies, including agents in a clinical trial, should be considered.
• Moxetumomab pasudotox-tdfk (Lumoxiti®) is approved for the treatment of adult patients with relapsed or refractory HCL who have received at least two prior systemic therapies, including treatment with a purine nucleoside analog 

For information about the drugs listed on this page, visit our cancer drug listing.  

Follow-up care 

HCL is considered a chronic form of cancer because it never completely goes away. Periodic medical examinations for patients in complete remission are important. Patients should have their blood counts checked routinely to ensure that they are still in remission. If blood counts begin to decline, patients need to discuss treatment options with their doctors.  

Find more information about follow-up care, including what to expect, long-term and late effects of treatment, survivorship clinics, and other resources, such as The National Comprehensive Cancer Network (NCCN) treatment guidelines.