Dr Abdul Mannan FRCPath FCPS

Blood 🩸 Doctor

[email protected]

[email protected]

Q: What are the implications of the reclassification of CML as biphasic ?

Based on the available evidence, there appears to be some confusion in the query. Chronic myeloid leukemia (CML) has not been reclassified as biphasic - rather, CML has long been recognized as having a biphasic or triphasic clinical course.

Current Understanding of CML Disease Progression

CML is characterized by a natural progression through distinct phases:

  1. Chronic phase (CP) - the initial, indolent phase
  2. Accelerated phase (AP) - an intermediate phase
  3. Blast phase (BP) - the terminal, acute leukemia-like phase

Patients initially diagnosed in chronic phase may progress to more aggressive disease, typically advancing through accelerated phase before evolving into blast phase [1].

Clinical Implications of CML's Multiphasic Nature

The recognition of CML's biphasic/triphasic course has several important implications:

  1. Treatment Response Varies by Phase: Management of patients in accelerated or blast phase is consistently less effective than treatment during chronic phase across all therapeutic approaches [1].
  2. Improved Therapies Slow Progression: Advances in therapy for chronic phase CML have significantly reduced the rate of progression to accelerated or blast phase [1].
  3. Diagnostic Challenges: The literature uses varying diagnostic criteria for accelerated and blast phases, making study comparisons difficult [1].
  4. Blast Phase Characteristics: While most CML blast phase patients present with myeloid blasts, 20-30% exhibit lymphoid phenotype blasts, predominantly B-cell phenotype [2].

The multiphasic nature of CML remains a fundamental characteristic that guides prognosis, treatment decisions, and monitoring strategies rather than representing a recent reclassification.

My Teaching Tips for CML