Monitoring

Clinic attendance is required every week or fortnight immediately following diagnosis and then every 3 months for the first year.

Full blood counts every 1-2 weeks are necessary after initiation of treatment for a period of 1-2 months or until stable, then as needed (e.g., if cytopenia persists).

Molecular monitoring with quantitative reverse transcription polymerase chain reaction (qRT-PCR) is required every 3 months.[5]

Bone marrow biopsy should be performed at presentation, but is not required for routine monitoring if effective molecular monitoring is available.

Once there has been a significant response (CCyR [≤1% BCR::ABL1]), follow-up visits should continue every 3 months for 2 years, and every 3-6 months subsequently, with appropriate laboratory monitoring.[5] If the levels of BCR::ABL1 transcripts increase, more frequent monitoring is required in both blood and potentially bone marrow, to monitor disease progress.[6][110]

Treatment response milestones

Quantification of BCR::ABL1 transcripts has been shown to predict progression-free survival. Most laboratories report results according to an international scale (IS).[36]

Monitoring BCR::ABL1 transcript levels (IS) for milestones at 3 months, 6 months, and 12 months helps to guide decisions about continuing or changing treatment.

The following IS molecular landmarks may be used to define a suboptimal, or 'warning', response to a first-line tyrosine kinase inhibitor (TKI) in the management of chronic-phase CML:[5]

  • At 3 months: BCR::ABL1 >10%

  • At 12 months: BCR::ABL1 >1% to 10%.

Patients with a suboptimal response require further evaluation for possible TKI resistance, and consideration of switching to an alternative TKI. Patient adherence to therapy and the potential role of drug interactions should be considered in patients with suboptimal response. Mutational analysis for BCR::ABL1 kinase domain mutations and bone marrow cytogenetic analysis may be considered to help guide decision-making.[5] An individualised approach, taking into account the clinical context, is recommended when milestones are not reached.[31][69]

TKI resistance, defined as BCR::ABL1 >10% at 6 months or later, indicates the need to change to an alternative TKI (and evaluation of the patient for allogeneic haematopoietic stem cell transplant).[5]

At 12 months, a response of >0.1% to 1% BCR::ABL1 may be optimal if the patient's goal is long-term survival; a response of ≤0.1% BCR::ABL1 may be optimal if the patient's goal is treatment-free remission.

For definitions of complete haematological response and cytogenetic response, see Classification.

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