Adherence to tyrosine kinase inhibitors is associated with improved outcomes in chronic myeloid leukemia patients. Hence, improved adherence might improve CML patients' prognosis.

Decreased adherence is a common problem in such patients, with non-adherence in up to 30% of patients in several studies. Recently, an emphasis has been placed on improving patient's adherence to tyrosine kinase inhibitors in these patients. However, there is no prospective high-quality evidence showing that adherence can be improved in these patients.

Therefore, the investigators hypothesize that adherence-encouraging interventions improve adherence to tyrosine kinase inhibitors in chronic myeloid leukemia patients.

The cytogenetic hallmark of chronic myeloid leukemia (CML) is the reciprocal translocation between chromosomes 9 and 22 creating the Philadelphia (Ph(1)) chromosome. The BCRABL1 fusion gene is the result of this translocation and encodes for a constitutively active tyrosine kinase responsible for the development of CML. Tyrosine kinase inhibitors (TKIs) targeting the protein product of this aberrant gene, the BCRABL-1 protein, have revolutionized the therapeutic approach to chronic myeloid leukemia (CML). Treatment with the first FDA approved TKI, imatinib mesylate (Gleevec, Novartis), in chronic phase CML results in a projected 8 year overall survival of 85%. Recently, two second generation TKIs, Dasatinib and Nilotinib, have been approved for use in newly diagnosed chronic phase CML, as a result of studies showing improved molecular and cytogenetic outcomes. Importantly, in each of the above studies there was a substantial number of dropouts due to drug intolerance and resistance, among other reasons. In a prospective observational study of 169 CML patients, only 14% of patients were fully adherent with prescribed imatinib. Moreover, one third of patients were considered to be non-adherent, which is similar to the proportion of dropouts in the landmark studies on TKIs in CML. Thus, it is clear that there is a subgroup of patients who do not properly adhere to treatment. This is especially significant because the contemporary approach to CML in complete cytogenetic remission (CCyR) and major molecular remission (MMR) necessitates long-term, chronic treatment with TKIs.

Therefore, although hematologists have the luxury of an armamentarium of highly effective drugs, one of the most challenging aspects of treating CML is the management of non-compliance to TKI treatment. TKI-induced adverse effects are only one of a wide spectrum of reasons for non-adherence to TKI treatment.

Recently several studies have demonstrated the prognostic importance of adhering to imatinib treatment. In a pivotal study of 87 chronic phase CML (CP-CML) patients in CCyR, an adherence rate of > 90% strongly correlated with the 6 year probability of achieving MMR (94.5% vs. 28.4% when adherence rates were ≤ 90%). Non-adherence to imatinib treatment also adversely affects event free survival and is associated with loss of CCyR in patients on long term treatment. These data support the intuitive concept that CML can be effectively treated with the drugs currently available, as long as patients adhere to treatment. Moreover, non-adherence to imatinib treatment has been associated with increased economic burden and healthcare costs. Consequently, TKI adherence is an attractive potential target for intervention.

Non-adherence to medication is an intricate problem that is influenced by the physician, the healthcare system, and economic and social factors. Other medical disciplines have assessed various modes of improving adherence to therapeutic regimens, with varying success. A recent study assessing adherence-related behavior among CML patients, demonstrated that among a multitude of reasons for non-adherence, patient forgetfulness and drug side effects were the most common causes of unintentional and intentional non-adherence, respectively. Several methods of improving adherence among patients with CML were retrospectively assessed by Moon et al. Subjects in the intervention arm were more likely to receive prescriptions for imatinib than those receiving standard care (98.2 ± 0.03% vs. 79.3 ± 0.16%). Although there was no difference in adherence to prescribed treatment between the two groups, the overall compliance, a composite endpoint of the above two outcomes, was markedly improved in the intervention group ((93.0 ± 2.3% vs. 76.2 ± 7.4%, P = 0.001). Recently, Gater et al conceived a conceptual model aimed at improving adherence in CML patients treated with 1st and 2nd generation TKIs, based on a systematic review of the literature. However, there are currently no prospective data evaluating whether adherence in CML can be influenced by active intervention.

Study Hypothesis:

Adherence to tyrosine kinase inhibitors (TKIs) is associated with improved outcomes in chronic myeloid leukemia (CML) patients. Hence, improved adherence might improve CML patients' prognosis.

The investigators hypothesize that adherence-encouraging interventions improve adherence to TKIs in CML patients.

Study Objective:

1. Primary Objective: By means of a prospective before-after study, the investigators aim to assess whether specific adherence-encouraging interventions improve TKI adherence in patients with CP-CML treated by these agents. The investigators will target previously documented reasons for non-adherence 11 with interventions that were selected based on prior experience in other medical disciplines and will evaluate their contribution to patients' adherence to treatment.
2. To better understand non-adherence in CML and pinpoint independent risk factors for non-adherence
3. To validate questionnaires assessing adherence, and evaluate whether they could be of use in indentifying patients at risk for non-adherence
4. To compare adherence to second generation TKIs with adherence to imatinib
5. To assess the role of a clinical pharmacist in preventing potential drug interactions
6. To determine whether the intervention has a long term effect on adherence during one year of post-intervention follow up
7. To estimate long term effects of adherence on clinical, cytogenetic and molecular outcomes

Inclusion Criteria:

• Patients with chronic phase chronic myeloid leukemia (CP-CML), aged 18 years or older

  • CP-CML defined as: Medical history of cytogenetically confirmed CP-CML defined as the presence of the Philadelphia chromosome on bone marrow aspirates (a minimum of 20 metaphases is required; FISH cannot be used). If Philadelphia chromosome was negative or if cytogenetic results were not available, BCR-ABL-positive CML patients can be included.

• At least 3 months of TKI treatment (imatinib, dasatinib or nilotinib) before study initiation.

Exclusion Criteria:

• Current or prior accelerated/blast phase or stem cell transplant
• Participation in another interventional study
• Pregnancy

The adherence assessed per study protocol was masked to participants and care providers during the preintervention and post intervention phases. At the time of intervention participants were notified once of their adherence as part of the feedback-based intervention