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Treatment Options for Hairy Cell Leukemia

Source: Hairy Cell Leukemia Treatment (PDQ®)–Health Professional Version, National Cancer Institute.

Source updated: February 21, 2025 · Captured 2026-09-09.

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Context: Treatment of Hairy Cell Leukemia

Prior to the COVID-19 (SARS-CoV-2) pandemic, the standard initial therapy for patients with hairy cell leukemia was infusion of cladribine daily for 5 days, given with or without eight weekly doses of rituximab.[2-4] However, treatment with a purine analogue–based regimen led to significant and prolonged neutropenia and impairment of T-cell function, which were both problematic during the pandemic in fighting viral infection and establishing vaccination-induced immunity.

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Other options for initial standard therapy, instead of cladribine or pentostatin, may offer less toxicity in terms of infection and long-term risk of secondary malignancies. However, these options may provide less durable response.

The Hairy Cell Leukemia Foundation convened a virtual meeting of 39 experts from around the world to amend the 2017 consensus recommendations.[5] The adapted treatment guidelines, published in 2021, are based primarily on anecdotal experience and expert opinion, as controlled trials for this indolent leukemia cannot be completed expeditiously given the low incidence of this disease.[6][Level of evidence C3] The adapted treatment guidelines are summarized below.

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Consider watchful waiting when feasible; asymptomatic patients with noncritical levels of pancytopenia can be monitored closely.

Cladribine, with or without rituximab,[4] remains the standard of care. However, due to the risk of serious and prolonged immunosuppression, nonchemotherapy treatment options may be preferable for older, frail patients with higher risk of infection (or for those who have active infections).

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BRAF inhibitors such as vemurafenib, dabrafenib, or encorafenib are nonchemotherapeutic options that can be combined with rituximab or obinutuzumab.[7-10] Most patients with hairy cell leukemia have BRAF pathogenic variants, but this should be verified by flow cytometry. Despite extensive experience with vemurafenib for patients with relapsed disease, the U.S. Food and Drug Administration (FDA) has not approved oral vemurafenib for patients with hairy cell leukemia.

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Consider using rituximab alone intravenously (IV) for 4 to 8 weeks or in combination with a BRAF inhibitor.[11] Anti-CD20 monoclonal antibodies can impair future vaccine response, but they do not affect immunity from prior vaccination.

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In patients with relapsed disease, the previously mentioned options are available, along with ibrutinib (the Bruton tyrosine kinase inhibitor).[12]

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Treatment options for hairy cell leukemia include:

Watchful waiting, if feasible.

Cladribine with or without rituximab.

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