Speaking the language of Ph+ CML

Patient portrayal of a woman

Getting to know the language of Ph+ CML

Below are definitions of terms used on this website. You may find it helpful to get familiar with this glossary, since your doctor may use these words in your conversations. The glossary also may be helpful in talking with family and friends about SCEMBLIX® (asciminib) tablets and Ph+ CML in chronic phase.


Accelerated phase: The second phase of chronic myeloid leukemia progression, characterized by an increase in the number of immature blast cells.

BCR-ABL1:  An abnormal gene that causes Ph+ CML. The BCR-ABL1 gene is formed when pieces of the 9 and 22 chromosomes swap places, creating a damaged protein—also called BCR-ABL.

BCR-ABL1 kinase domain mutation analysis: A test that helps identify mutations in the BCR-ABL1 gene that may cause patients to become resistant to certain medications for Ph+ CML in chronic phase.

Blast cell: A white blood cell that is immature.

Blast phase: The third phase of chronic myeloid leukemia with the highest number of immature blood cells (blast cells) in the blood and bone marrow.

Bone marrow: Soft, sponge-like tissue at the center of most bones responsible for creating blood cells.

Chromosome: Within a cell, these long strands contain bundles of coded instructions for creating and controlling cells.

Chronic myeloid leukemia (CML): Beginning in the bone marrow, this blood cancer causes an overproduction of damaged white blood cells.

Chronic phase: The first phase of CML progression when the number of white blood cells is elevated but may not result in symptoms. 

Complete blood count (CBC) test: Measures the number and different types of blood cells.

Complete cytogenetic response (CCyR): No Ph+ chromosomes are found in the bone marrow sample.

Cytogenetic testing: This involves testing samples of tissue, blood, or bone marrow in a laboratory to look for changes in chromosomes.

Gene: Complex, coded instructions contained within cells for making new cells and controlling cell behavior.

Gene mutation: A change in the DNA of a cell.

Intolerance: When side effects of a certain drug become so bothersome to a patient that the doctor decides to stop a medication.

Leukemic cells: Diseased white blood cells that grow abnormally.

Major molecular response (MMR): Tests detect a low amount of BCR-ABL1 in the blood (≤0.1%). This percentage means 1 out of every 1000 cells has the BCR-ABL1 gene.

Milestone: An optimal clinical treatment response over a fixed period of time.

Molecular response: Refers to a decrease in the number of cells in the blood with BCR-ABL1.

Mutation testing: Testing for abnormal changes in genes.

Philadelphia chromosome (Ph): An abnormal chromosome formed when parts of chromosomes 9 and 22 switch places, which creates the BCR-ABL1 gene. The presence of the Philadelphia chromosome shows that chronic myeloid leukemia (CML) is in the body.

Platelets: Found in the blood and spleen, platelets help form blood clots to slow down or stop bleeding.

Protein: Essential for proper body function, a protein consists of amino acids.

qPCR test (quantitative polymerase chain reaction test): Sensitive lab test that can be performed on either the blood or bone marrow to identify leukemia cells.

Red blood cells: Made in the bone marrow, these blood cells contain a protein called hemoglobin, which carries oxygen from the lungs to other parts of the body.

Resistance: When a patient does not respond to a medication, or stops responding to treatment.

T315I gene mutation: A mutation associated with clinical resistance to most tyrosine kinase inhibitors (TKIs).

Tyrosine kinase inhibitors (TKIs): A type of targeted drug that attaches to the BCR-ABL protein to inhibit growth signals. Doctors use TKIs to treat Ph+ CML in chronic phase.

White blood cells: Help the body fight infections. Patients with Ph+ CML have too many immature leukemic white blood cells, which can crowd out healthy white blood cells, red blood cells, and platelets. The immature, leukemic cells are abnormal and do not become healthy white blood cells.