Discontinuation of biological therapy with tyrosine kinase inhibitors in chronic myeloid leukemia patients
Abstract
Imatinib mesylate, the first tyrosine kinase inhibitor (TKI) approved for the treatment of chronic myeloid leukemia (CML), became the standard of care, induces durable responses and prolongs event-free survival and progression-free survival. However, if TKI therapy is required indefinitely, then this ongoing drug exposure raises its own problems.
Long-term follow-up indicates that an increasing proportion of patients treated with TKI have prompt cytogenetic response and achieve reductions in BCR-ABL1 transcripts to a level that is undetectable by very sensitive molecular genetic methods. Observation of the stability of such responses over long follow-up suggests that such patients may be "functionally cured" of CML and thus potentially eligible for TKI therapy discontinuation.
At present, therapy discontinuation in CML is not recommended in routine practice and is under active investigation in several clinical studies worldwide. Many questions remain regarding definition of "functional cure" in CML, which patients are most eligible for safe therapy discontinuation, and what management strategies are recommended post discontinuation, especially regarding subsequent molecular relapse.