Update on hairy cell leukemia

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Hairy cell leukemia (HCL) is a chronic B-cell malignancy characterized by specific cellular markers and mutations like BRAF V600E.
• HCL variants, such as HCLv and those with unmutated IGHV4-34, exhibit more aggressive behavior.
• Current first-line treatment involves purine analogues, achieving high remission rates but often leaving minimal residual disease (MRD).

Purpose of the Study:

• To review the current treatment landscape for Hairy cell leukemia (HCL).
• To discuss the challenges of MRD and relapse associated with standard therapies.
• To highlight emerging investigational therapies targeting specific molecular pathways in HCL.

Main Methods:

• Review of existing literature on HCL diagnosis, treatment, and outcomes.
• Analysis of standard first-line treatments (purine analogues) and their efficacy and limitations.
• Examination of novel therapeutic agents, including monoclonal antibodies and targeted therapies.

Main Results:

• Purine analogues (cladribine, pentostatin) are standard first-line treatments yielding high complete remission rates.
• Minimal residual disease (MRD) is common after purine analogue therapy, leading to frequent relapses.
• Rituximab combined with purine analogues improves remission rates and reduces MRD but adds toxicity.
• Investigational therapies targeting CD22, BRAF V600E, MEK, and BTK offer new non-chemotherapy options.

Conclusions:

• While purine analogues remain a cornerstone of HCL treatment, their limitations regarding MRD and cumulative toxicity necessitate alternative strategies.
• Combination therapy with rituximab can enhance efficacy but requires careful toxicity management.
• Targeted investigational therapies represent a promising frontier for overcoming treatment resistance and improving long-term outcomes in HCL.