From the Guidelines
The first-line treatment for hairy cell leukemia is typically a purine nucleoside analog, with cladribine (2-CdA) being the preferred agent, as it offers a high complete remission rate and durable responses, as noted in the most recent guidelines 1.
Treatment Options
The treatment options for hairy cell leukemia include:
- Cladribine (2-CdA) administered as a single course at 0.1 mg/kg/day by continuous intravenous infusion for 7 days, or alternatively as a subcutaneous injection at the same dose for 5-7 days
- Pentostatin, an alternative purine analog, given at 4 mg/m² intravenously every other week until complete remission plus 1-2 additional treatments
Initiation of Treatment
Treatment should be initiated when patients develop 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 consensus guidelines for the diagnosis and management of patients with classic hairy cell leukemia 1.
Mechanism of Action
Purine analogs work by selectively accumulating in lymphocytes with high deoxycytidine kinase and low 5'-nucleotidase levels, causing DNA damage and triggering apoptosis in the leukemic cells, as described in the study on hairy cell leukemia and COVID-19 adaptation of treatment guidelines 1.
Prophylaxis
Patients should receive prophylaxis against herpes zoster and Pneumocystis jirovecii during and after treatment due to the prolonged immunosuppression these medications cause, as recommended in the guidelines for the diagnosis and treatment of hairy cell leukemia 1.
From the FDA Drug Label
In these studies, 60% of the patients had not received prior chemotherapy for Hairy Cell Leukemia or had undergone splenectomy as the only prior treatment and were receiving cladribine as a first-line treatment The overall response rate for patients without prior chemotherapy was 92%, compared with 84% for previously treated patients The first-line treatment options for hairy cell leukemia include cladribine (IV), with an overall response rate of 92% in patients without prior chemotherapy 2.
- Key points:
- Cladribine is active in previously treated patients, but the overall response rate is decreased in patients previously treated with splenectomy or deoxycoformycin and in patients refractory to α-interferon
- The median time to normalization of peripheral blood counts was 9 weeks from the start of treatment
- The median duration of complete response was greater than 8 months and ranged to 25+ months 2
From the Research
First-Line Treatment Options for Hairy Cell Leukemia
The first-line treatment options for hairy cell leukemia include:
- Purine analogs such as cladribine and pentostatin, which have been shown to be effective in achieving complete remissions in a high percentage of patients 3, 4, 5
- Combination therapy with rituximab, a monoclonal antibody, and a purine analog, which has been shown to improve response rates and duration of response compared to purine analog therapy alone 3, 6
Efficacy of Cladribine and Pentostatin
Studies have demonstrated that:
- Cladribine and pentostatin have similar efficacy in the treatment of hairy cell leukemia, with complete response rates of 81% and median disease-free survival of 16 years 4
- Cladribine is often preferred as the initial therapy due to its durability and efficacy 5
Role of Rituximab
Rituximab has been shown to:
- Enhance the efficacy of purine analogs in the treatment of hairy cell leukemia, particularly in patients with minimal residual disease 3, 6, 7
- Improve the duration of response and reduce the risk of relapse when used in combination with a purine analog 6
Detection of Minimal Residual Disease
Minimal residual disease can be detected using various techniques, including: