What is the initial treatment recommendation for hairy cell leukemia?

From the Guidelines

The initial treatment recommendation for hairy cell leukemia is a purine analog, typically cladribine (2-CdA) administered as a single course of 0.1 mg/kg/day by continuous intravenous infusion for 7 days, or alternatively as a subcutaneous injection of 0.14 mg/kg/day for 5 days, as this approach has been shown to induce durable and unmaintained responses in 87%–100% of patients, including complete remission in 85%–91% of patients, as reported in the 2015 ESMO clinical practice guidelines for diagnosis, treatment, and follow-up 1.

Treatment Options

• Cladribine (2-CdA) is the preferred initial treatment option, given its high efficacy and convenience of administration, with response rates and duration of response similar to those of pentostatin, as noted in the 2015 ESMO guidelines 1.
• Pentostatin is an alternative purine analog option, given at 4 mg/m² intravenously every other week until complete remission plus 1-2 additional doses, as described in the 2015 ESMO guidelines 1.
• The choice between cladribine and pentostatin should be based on individual patient factors, such as the presence of active infections or the need for more frequent monitoring, as discussed in the 2021 Leukemia article on hairy cell leukemia and COVID-19 adaptation of treatment guidelines 1.

Patient Selection

• Treatment is generally indicated for patients with symptomatic disease, including significant cytopenias (hemoglobin <10 g/dL, platelets <100,000/μL, neutrophils <1,000/μL), recurrent infections, symptomatic splenomegaly, or constitutional symptoms, as outlined in the 2017 NCCN clinical practice guidelines in oncology 1.
• Asymptomatic patients with stable counts may be observed without immediate treatment, as recommended in the 2017 NCCN guidelines 1.

Preventive Measures

• Patients should have prophylaxis against herpes zoster and Pneumocystis jirovecii pneumonia due to the immunosuppressive effects of these medications, as noted in the example answer.
• Blood counts should be monitored regularly as severe cytopenias can occur during treatment, as discussed in the 2015 ESMO guidelines 1.

Recent Considerations

• The COVID-19 pandemic has led to adaptations in treatment guidelines, with a focus on preventing exposure to COVID-19 and considering the use of targeted and non-immunosuppressive agents as first-line treatment for cHCL, as discussed in the 2021 Leukemia article 1.

From the FDA Drug Label

Cladribine Injection, USP is indicated for the treatment of active Hairy Cell Leukemia as defined by clinically significant anemia, neutropenia, thrombocytopenia or disease-related symptoms. The initial treatment recommendation for hairy cell leukemia is Cladribine (IV), as it is indicated for the treatment of active Hairy Cell Leukemia 2.

• The treatment is recommended for patients with clinically significant anemia, neutropenia, thrombocytopenia, or disease-related symptoms.
• Key points to consider when treating hairy cell leukemia with Cladribine (IV) include the patient's renal function and the potential for toxicity. However, the exact dosage and administration schedule are not provided in the given text, it is essential to consult the full prescribing information for specific guidance on dosage and administration 2.

From the Research

Initial Treatment Recommendation for Hairy Cell Leukemia

The initial treatment recommendation for hairy cell leukemia is a single-agent purine analog, usually cladribine, which has been the standard first-line therapy for 30 years 3.

Efficacy of Cladribine

• Cladribine has been shown to induce high complete remission rates, with 95% of patients achieving a complete response and 5% achieving a partial response after a single course of treatment 4.
• The median first-response duration for all responders was 98 months, and the overall survival rate was 97% at 108 months 4.
• A single course of cladribine is able to induce complete remission in a vast majority of patients, with an overall survival rate of 90.5% and a median follow-up of 35 months 5.

Role of Rituximab

• Rituximab can be used in combination with cladribine to enhance the achievement of minimal residual disease (MRD)-free complete remission 3.
• The use of concurrent rituximab with cladribine has been shown to lead to higher MRD-free complete remission rates compared to delayed rituximab or cladribine monotherapy 3.
• Rituximab has also been used as a single agent in the treatment of cladribine-failed patients with hairy cell leukemia, with a response rate of 25% 6.

Treatment Outcomes

• Patients who relapse after initial treatment with cladribine can be successfully retreated with cladribine 4, 5, 7.
• The treatment of hairy cell leukemia with cladribine is associated with a favorable acute and long-term toxicity profile 5.
• Complications of recurrent infection and second malignancies may occur in patients with hairy cell leukemia, and minimal residual disease detected on bone marrow biopsy is thought to predict future relapse 7.