Chronic or acute myeloid leukemia are two forms of a serious genetic disease. Unlike other genetic disorders, this one can develop long after birth.

Chronic myelogenous leukemia (CML) is a form of blood cancer, that is, a disorder related to the proliferation of cells that are normally beneficial to the body but whose role is transfigured by the disease.

The case of leukemia

In the case of leukemia, these cells are the stem cells of the blood, called myeloid stem cells. Stem cells are “source” cells for the body, able to adapt to perform different roles. They are produced in the bone marrow (hence the term “myeloid”), at the heart of our bones. Their normal development is to become blast cells, still immature blood cells, before becoming really mature and joining red blood cells, white blood cells or even platelets.

The case of myeloid leukemia

In the case of severe stage myeloid leukemia, these blast cells remain blocked at this immature stage and will proliferate in the blood, replacing mature blood cells. This will naturally prevent the blood network from properly transmitting vital oxygen to other cells, and therefore lead to many failures of the body.

Chronic myelogenous leukemia accounts for 15-20% of all leukemia in adults, and is more commonly found in men over 50.

The main difference between the two stages is their severity.

Chronique

The chronic stage of myeloid leukemia is the basic one. It remains minor in terms of consequences on the body, because the myeloid stem cells have not yet completely taken the upper hand over those in the blood. The term “chronic” refers to the slow progress of the disease, which will take some time to progress to the acute stage.

Acute

This stage is the course of chronic disease. When it is reached, the patient’s hopes are diminished, the evil spreading indeed widespread in the organism, with an almost uncontrollable proliferation of abnormal stem cells.

Since the progression of the “chronic” disease is by definition quite slow, the symptoms will initially be difficult to spot. It is their accumulation and aggravation that can raise the alarm.

• Tired ;
• Loss of appetite ;
• Night sweats ;
• Abnormal weight gain, feeling of abdominal bloating;
• Pale skin ;
• More frequent infections, bruises and bleeding

The different phases of CML

Myeloid leukemia will go through different phases. Initially, the so-called “chronic” period, the patient will see very few symptoms, or even be asymptomatic. This phase can last for 5 to 6 years, before evolving into a more severe phase, in which the symptoms will be more frequent and become more serious.

Finally, in the acute phase, blast cells appear in the blood, which will lead to infections and bleeding. The spleen is also at risk of swelling as a result of enlargement, as are the lymph nodes.

Myeloid leukemia is caused by a genetic mutation, linked to the development of the individual rather than a malformation during fertilization (such as trisomy 21 syndrome, for example). It is therefore not hereditary and cannot be detected by family prevention. In CML, the cause is due to an abnormality in the Philadelphia chromosome (named after the city in the United States where it was discovered). In detail, it is the result of the fusion of two genes from chromosomes number 9 and 22, the bcr and abl genes, hence the term “bcr-abl fusion” which is sometimes found in the medical literature. .

The Philadelphia chromosome will produce a new enzyme in the body, tyrosine kinase, which will speed up the production of blast cells in the blood, in the most severe stage of the disease.

The diagnosis of chronic myeloid leukemia is most often made by blood sample, in order to identify an abnormally high level of white blood cells. The laboratory will also have to carry out a molecular test and an analysis of the patient’s chromosomes, in search of the fusion ” bcr-abl ”mentioned above.

There are various possible treatments for CML. The prognosis has improved in recent years, with a survival rate out of five much higher for the majority of patients treated. It is ideal to spot the disease as early as possible, in order to follow treatment even if there are no symptoms.

Tyrosine kinase blocker drugs

Tyrosine kinase is produced by the Philadelphia chromosome, and will produce excess white blood cells in the body. Its production can therefore be inhibited with the help of treatments such as imatinib, nilotinib, dasatinib, bosutinib and ponatinib.

Grafts of the stem ones

More serious treatment, it is suitable for patients who react badly or little to tyrosine kinase inhibitors (called TKIs). This is about bringing new myeloid stem cells directly to the body.