Addressing Fluctuating BCR-ABL Levels in CML

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Fluctuations in BCR-ABL levels occurs frequently, and this often alarms patients, Neil Pravin Shah, MD, comments. To assess these fluctuations, Shah looks at the degree of change. All of the panelists consider a full log increase a cause for concern.

Shah and Stuart L. Goldberg, MD, agree that a dramatic increase in a patient’s BCR-ABL level may indicate a patient’s nonadherence to therapy. They state that a more gradual rise often indicates resistance. However, Shah states that if the level has jumped, he still feels obligated to check for a resistance mutation, since resistance could still be contributing to the change in BCR-ABL.

B. Douglas Smith, MD, states that if there is a rise in BCR-ABL levels, but not a full-log increase, he continues to use the 3-month monitoring schema. For a significant increase, which he defines as a log or greater, he recommends that the patient return for monitoring after 6 to 8 weeks instead of after 3 months.

Shah describes the worst case scenario as one in which a patient’s BCR-ABL level fluctuates between undetectable or weakly positive and being quantifiable. This scenario is challenging because it is usually not possible to determine how far below detectable the patient was, making it difficult to quantify the exact change.