CALLS: CML and Ph+ALL Low Level Mutation Prevalence Survey

Inclusion Criteria: * Adult patients (age ≥ 18 years) with CML (in all phases of disease) or Ph+ ALL with detectable BCR-ABL levels who are being treated with a first or subsequent TKI. * Patients with CML must meet the warning or failure criteria as per the ELN guidelines for first second and subsequent treatment line, including: * BCR-ABL/ABL IS transcripts \> 10% at 3 months * BCR-ABL/ABL IS transcripts \> 1% at 6 months * BCR-ABL/ABL IS transcripts \> 0.1% at 12 months or later * Patients with CML must not currently be in MMR (ie, have disease with BCR-ABL1/ABL1 transcripts \> 0.1% IS). OR * Patients with Ph+ ALL with any level of BCR-ABL/ABL IS transcripts. Patients with Ph+ ALL should have BCR-ABL1/ABL1 transcript levels \> 0.1% and should not be currently enrolled in UKALL14 but may have relapsed during or after participation in UKALL14. * Patients with an intermediate or high Sokal score (\> 0.8) can be recruited into the study from 3 months after diagnosis, irrespective of BCR-ABL1/ABL1 transcript levels at 3 months. * Patients with additional chromosomal abnormalities at diagnosis and patients with AP-CML may be recruited into the study, irrespective of BCR-ABL1/ABL1 transcript levels at 3 months and beyond provided BCR-ABL1/ABL1 transcript levels are \> 0.1% IS. It is recommended that these patients have mutational analysis performed every 3 months irrespective of BCR-ABL1/ABL1 transcript levels until they reach MR3/MMR (BCR-ABL1/ABL1 \< 0.1% IS). * Any patients who have previously undergone testing for KD mutations, irrespective of KD mutational analysis test results. * Patients who have the ability to understand the requirements of the study and provide written informed consent. Exclusion Criteria: Patients without detectable BCR-ABL and patients who have switched TKI due to intolerance but who have met the criteria for optimal response (CP-CML, ELN 2013 guidelines).