Hairy cell leukaemia variant (HCL-V) is a distinct entity typically presenting with high lymphocyte counts. The leukaemic cells are nucleolated; monocytopenia — a hallmark of classic HCL — is absent. Immunophenotypically, HCL-V is CD25-negative, and the BRAF V600E mutation is not present.
This protocol addresses patients who received initial treatment with 2-CldA immediately followed by rituximab but did not achieve the required endpoint: a complete response with eradication of minimal residual disease. Failure to reach that goal is the trigger for escalation to this next line.
After failure of initial combination therapy, the protocol recommends targeted antibody-based therapy and, in appropriate patients, spleen-directed interventions — the full structured protocol specifies selection, sequencing, and all relevant criteria.
DOI: 10.1093/annonc/mdv200
HCL-V typically presents with high lymphocyte counts, with the cells being nucleolated and lacking monocytopaenia.
Although HCL-V patients lack the BRAF mutation, TP53 mutations are present in one-third of cases [13].
Alternatively, individual case reports suggest that alemtuzumab is an active agent in treating HCL-V, even in patients who have relapsed after rituximab [64].
Splenectomy induces clinical responses in some patients with HCL-V, and is recommended because it corrects cytopaenias, removes the bulk of the tumour and may improve response to purine nucleoside analogues [V, B] [65].
Splenic irradiation could be performed in elderly patients with a high surgical risk of splenectomy [V, B].
Clinical case reports support the use of moxetumomab pasudotox in patients with HCL-V [V, B] [44].
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