Hairy cell leukaemia

Treatment response criteria[33]Grever MR, Abdel-Wahab O, Andritsos LA, et al. Consensus guidelines for the diagnosis and management of patients with classic hairy cell leukemia. Blood. 2017 Feb 2;129(5):553-60. https://www.doi.org/10.1182/blood-2016-01-689422 http://www.ncbi.nlm.nih.gov/pubmed/27903528?tool=bestpractice.com ​​

Complete response (CR)

• Near normalisation of peripheral blood counts:

  • Haemoglobin >110 g/L (>11 g/dL) (without transfusion)

  • Platelets >100,000/microlitre

  • Absolute neutrophil count >1500/microlitre

• Regression of splenomegaly on physical examination

• Absence of morphological evidence of HCL on both the peripheral blood smear and the bone marrow examination.

CR with or without minimal residual disease (MRD)

• Based on immunohistochemical assessment of the percentage of MRD in patients who achieved a CR.

Partial response (PR)

• A PR requires near normalisation of the peripheral blood count (as in CR) with a minimum of 50% improvement in organomegaly and bone marrow biopsy infiltration with HCL.

Stable disease (SD)

• Patients who have not met the criteria for an objective remission after therapy are considered to have SD.

• Patients with HCL are treated for specific reasons (e.g., disease-related symptoms or decline in their haematological parameters) therefore SD is not an acceptable response.

Progressive disease (PD)

• Patients with any of the following:

  • Increase in symptoms related to disease

  • 25% increase in organomegaly

  • 25% decline in haematological parameters.

• An effort must be made to differentiate a decline in blood counts related to myelosuppression effects of therapy versus PD.

HCL in relapse

• Morphological relapse: reappearance of HCL in the peripheral blood, the bone marrow biopsy, or both by morphological stains in the absence of haematological relapse.

• Haematological relapse: reappearance of cytopenia(s) below the thresholds defined for CR and PR.

• Whereas no treatment is necessarily needed in case of morphological relapse, treatment decisions for a haematological relapse are based upon several parameters (e.g., haematological parameters warranting intervention, reoccurrence of disease-related symptoms).