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Most people with chronic myeloid leukemia (CML) are treated with a type of targeted therapy called tyrosine kinase inhibitors (TKIs).

Over time, some CML medications don't work as well as they used to

Some people with CML find that over time, the number of leukemic cells in their blood starts going up instead of staying stable or going down. This may be due to drug resistance, which happens when cancer cells no longer respond to a medication.

Over time, you may experience any of the following:

  • Treatment doesn’t work: This is called primary drug resistance
  • Treatment worked for a time, but it no longer works as well: This is called secondary drug resistance
  • Drug intolerance: Side effects of a medication become unacceptable and significantly affect daily life. Learn more

To have a conversation with your doctor about how you are doing with your CML treatment, you may find this Doctor Discussion Guide helpful.

Your doctor may discuss CML treatment milestones with you.

What is your CML treatment goal?

Below describes treatment milestones in CML. One goal is to reduce the number of cells with the BCR-ABL1 gene to as close to zero as possible.

Chart showing ideal CML treatment based on the level of BCR-ABL1 in the blood.


This chart shows an example of how your blood counts may come down with medication. If your BCR-ABL1 increases, or you do not achieve your CML treatment goals, you may want to ask your doctor about other treatment options.

Treatment goals vary by patient. Not every patient will reach these CML milestones.


Details of each CML milestone

Image showing CML milestones from diagnosis baseline to EMR or CHR to CCyR to MMR to DMR to CMR.
Image showing CML milestones from diagnosis baseline to EMR or CHR to CCyR to MMR to DMR to CMR.
Image showing CML milestones from diagnosis baseline to EMR or CHR to CCyR to MMR to DMR to CMR.
Image showing CML milestones from diagnosis baseline to EMR or CHR to CCyR to MMR to DMR to CMR.

Know your numbers

Your doctor may want you to go for blood tests to see if you are responding to your medication. Here are tests your doctor may order:

  • Measures the amount of red blood cells, white blood cells, and platelets in the blood
  • Analyzes a small sample of bone marrow under a microscope to determine the number of cells with the Ph chromosome
  • A standard cytogenetic test may not detect all the CML cells in the blood. Your doctor may order a fluorescence in situ hybridization (FISH) test, which uses fluorescent dyes and a fluorescent microscope to measure the number of cells with the Ph chromosome
  • The quantitative polymerase chain reaction test (qPCR) measures your BCR-ABL1 level and is the standard for monitoring response to CML medications
  • The qPCR test is sensitive enough to detect the smallest amount of leukemic cells in the blood and bone marrow
  • It can identify 1 cancer cell among anywhere from 100,000 to 1 million cells
  • When you go for qPCR testing, be sure the lab uses a standardized scale called the International Scale (IS) to measure your BCR-ABL1 level
  • qPCR testing is typically done every 3 months for 2 years, then every 3 to 6 months thereafter. Discuss with your doctor how often you should get tested

An increase in your BCR-ABL1 levels can be a red flag for your doctor. That’s why it’s important to go for any blood tests your doctor prescribes and discuss what your results mean with your doctor

Your doctor may track your BCR-ABL1 with a qPCR test. It’s so sensitive it can detect 1 cancer cell among 100,000 to 1 million cells.

Gene mutation testing

In CML, one of the causes of resistance is a mutation in the BCR-ABL1 gene. A mutation is a change in a cell’s DNA.

To determine if you have a mutation, your doctor may order a test called a BCR-ABL1 kinase domain mutation analysis. This test looks for mutations in the BCR-ABL1 gene that may cause certain medications to stop working.

Your doctor may decide to test for a mutation if you are:

  • Not responding or no longer responding to medication
  • Unable to reach a treatment milestone
  • Progressing to the accelerated phase or blast phase

Keep up with your blood work

It’s important to work closely with your doctor to manage your CML. You have to do your part, which includes going for blood tests and keeping up with your doctor visits. Be sure to discuss the results of your blood tests with your doctor. This way, you can see if you are responding to treatment.

Use the Doctor Discussion Guide

If you’re not reaching your CML treatment goals, use this Doctor Discussion Guide. It has questions you can ask your doctor that can help you find a CML medication that may be right for you.

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