Leukemia-Chronic Myeloid Leukemia (CML)

Chronic Myeloid Leukemia (CML)

Chronic Myeloid Leukemia (CML) is a type of blood cancer that originates in the bone marrow and affects myeloid cells, which give rise to white blood cells (WBCs), red blood cells (RBCs), and platelets. It is also known as chronic granulocytic leukemia or chronic myelogenous leukemia. In CML, the overproduction of immature WBCs, particularly granulocytes or neutrophils, disrupts normal blood cell production.

Philadelphia Chromosome and Genetic Mutation in CML

• Philadelphia chromosome is a genetic abnormality found in almost all cases of CML.

• It occurs due to a translocation, where part of chromosome 9 attaches to chromosome 22, forming the BCR-ABL fusion gene.

• This fusion gene produces a tyrosine kinase protein, which drives the overproduction of WBCs, leading to leukemia.

• This mutation is acquired after birth and is not inherited, meaning it is not passed on to future generations.

About CML Progression

In a healthy person, the production of WBCs is regulated and increases only during infection or stress. However, in CML, WBC production continues uncontrollably, leading to:

• Elevated WBC and platelet counts

• Decreased RBC counts, causing anemia

CML develops slowly, and many patients may not exhibit symptoms in the early stages. Often, it is diagnosed during routine blood tests.

Statistics

• In India, leukemia accounts for around 48,419 cases annually, with CML making up 15% of all leukemia cases.

• In the U.S., about 8,930 new cases of CML are diagnosed each year.

• CML is most common in adults aged 64 and older, with 50% of cases occurring in those over 65 years. It is rare in children.

Survival Rate

• 5-year survival rate: 70%

Risk Factors

Although the exact cause of CML is unknown, certain factors may increase the risk:

• Age: Most common around the age of 64; rare in children.

• Gender: Men are more likely to develop CML than women.

There is no clear link between CML and factors such as radiation exposure, chemicals, or chemotherapy.

Symptoms

CML progresses slowly, and symptoms may take years to appear. When symptoms do develop, they include:

• Fatigue and weakness

• Shortness of breath during physical activities

• Fever and night sweats

• Unintended weight loss

• Abdominal discomfort or bloating (due to an enlarged spleen)

• Fullness after eating small amounts

• Bone pain

• Frequent infections

• Bleeding and easy bruising

Diagnosis

1. Complete Blood Count (CBC):

• Detects elevated WBC and platelet counts with reduced RBCs.

2. Bone Marrow Aspiration and Biopsy:

• Confirms the diagnosis by analyzing bone marrow samples.

• Bone marrow fluid and tissue are extracted from the hip bone for examination.

3. Genomic and Molecular Testing:

• Fluorescence in situ hybridization (FISH) and Polymerase Chain Reaction (PCR) detect the BCR-ABL fusion gene and Philadelphia chromosome.

4. Imaging Tests:

• CT Scan and Ultrasound help assess the size of the spleen and detect other abnormalities.

Treatment Options

1. Targeted Therapy (Tyrosine Kinase Inhibitors - TKIs):

• TKIs block the abnormal BCR-ABL protein produced in CML, stopping the uncontrolled growth of WBCs.

• Common TKIs include:

• Imatinib (Gleevec): First TKI developed for CML, administered orally once or twice a day.

• Dasatinib (Sprycel): Used when Imatinib is ineffective or for newly diagnosed cases.

• Nilotinib (Tasigna): Similar to Dasatinib, used in resistant cases or as first-line treatment.

• Bosutinib (Bosulif): For patients who do not respond to other TKIs.

• Ponatinib (Iclusig): For patients with specific mutations resistant to other TKIs.

Note: Men and women undergoing TKI therapy should avoid pregnancy, as the drug can cause birth defects.

2. Bone Marrow/Stem Cell Transplantation:

• Allogeneic Stem Cell Transplantation (ALLO):

• Uses healthy stem cells from a donor to replace damaged bone marrow.

• This procedure is reserved for high-risk or relapsed CML cases.

• Involves high-dose chemotherapy or radiation to destroy cancer cells, followed by a stem cell transplant to restore healthy blood production.

Side Effects of Treatment

1. TKIs:

• Nausea, diarrhea, fluid retention, muscle cramps, and fatigue.

2. Chemotherapy:

• Hair loss, nausea, vomiting, and increased risk of infections.

3. Bone Marrow Transplant:

• High risk of infections and graft-versus-host disease (GVHD) if the donor’s immune cells attack the recipient’s tissues.

Follow-Up Care

• Regular Monitoring:

• Blood tests and physical exams are required at regular intervals to track disease progression and treatment response.

• Managing Side Effects:

• Patients may need additional medications to manage infections, anemia, or GVHD.

• Emotional Support:

• Counseling or mental health support may help patients cope with the challenges of living with CML.

CML is a manageable chronic disease with advanced treatments like TKIs offering promising outcomes. With proper monitoring and therapy, most CML patients can maintain a good quality of life. However, stem cell transplantation may be needed for patients with aggressive or treatment-resistant disease. Regular follow-up and supportive care are essential to ensure the best outcomes.

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