Chronic Myeloid Leukemia (CML)

Name: Chronic Myeloid Leukemia (CML)
Uploaded: 2023-05-26T14:00:34.000Z
Duration: 1 h 38 min 3 s

Chronic Myeloid Leukemia (CML) Overview

In this section, the speaker introduces chronic myeloid leukemia (CML) and highlights the importance of understanding the disease's pathophysiology.

Understanding Chronic Myeloid Leukemia

CML is a type of disease that involves abnormalities in the hematopoiesis pathway.

The disease originates from pluripotent stem cells in the bone marrow, leading to abnormal differentiation and proliferation of cell lines.

In CML, myeloid stem cells replicate excessively but can differentiate into specific granulocytes, unlike acute myeloid leukemia (AML) where differentiation is impaired.

Pathophysiology of Chronic Myeloid Leukemia

This section delves deeper into the pathophysiology of CML, focusing on the differentiation and proliferation patterns of myeloid stem cells.

Proliferation and Differentiation in CML

In CML, myeloid stem cells proliferate rapidly and differentiate into various stages: pro-myelocyte, myelocyte, meta-myelocyte, and band cells before becoming functional white blood cells like neutrophils.

Unlike AML where there is uncontrolled proliferation without differentiation, CML shows controlled proliferation with differentiation into specific cell types.

Factors Influencing Chronic Myeloid Leukemia

This part discusses potential factors contributing to the over-proliferation observed in chronic myeloid leukemia.

Potential Causes of Over-Proliferation

Ionizing radiation is suggested as a possible cause for mutations leading to over-proliferation in CML.

Ionizing Radiation and Genetic Associations

In this section, the discussion revolves around the impact of ionizing radiation on genetic mutations and the genetic associations related to a specific disease.

Ionizing Radiation and Mutation Effects

Ionizing radiation can potentially induce mutations, stimulating oncogenes or proto-oncogenes while inhibiting tumor suppressor genes.

Genetic associations with diseases are often linked to chromosomal translocations, such as the 9;22 translocation seen in a particular disease.

Chromosomal Translocation and Fusion Genes

Chromosomal translocation involves swapping genetic material between chromosomes 9 and 22, resulting in the formation of a fusion gene like BCR-ABL.

The Philadelphia chromosome is formed by fusing the ABL gene from chromosome 9 with the BCR gene from chromosome 22.

Impact of Fusion Gene on Cell Proliferation

The BCR-ABL fusion gene leads to excessive cell proliferation and decreased apoptosis, allowing cells to divide continuously without dying.

Activation of tyrosine kinase receptor by BCR-ABL stimulates cellular proliferation, contributing to the disease's progression.

Genetic Association with CML Progression

This part delves into how the 9;22 translocation causing BCR-ABL formation drives increased cellular proliferation and reduced apoptosis in Chronic Myeloid Leukemia (CML).

Disease Association and Cellular Effects

The 9;22 translocation leading to BCR-ABL formation results in uncontrolled cell division due to increased cellular proliferation and inhibited apoptosis.

CML Phases: Chronic Phase Progression

Exploring the triphasic appearance of CML focusing on its chronic phase progression characterized by accelerated myeloid stem cell differentiation.

Triphasic Appearance and Cellular Differentiation

CML exhibits three phases: chronic, accelerated, and blast phases. The chronic phase involves accelerated production of neutrophils, eosinophils, basophils from myeloid stem cells.

Cellular Changes in Disease Progression

Discussing how continuous replication cycles lead to mutations affecting myeloid stem cell differentiation during CML progression.

Mutation Impact on Differentiation

Replication-induced mutations decrease myeloid stem cell differentiation over time during CML progression.

Transition to Accelerated Phase

Transitioning into accelerated phase where functional white blood cells decrease while immature forms increase due to impaired differentiation.

Impaired Differentiation Consequences

Leukemia Progression and Effects on the Body

In this section, the speaker discusses the progression of leukemia, specifically chronic myeloid leukemia (CML), and its effects on the body.

Leukocyte Production and Mutation

Neutrophils, eosinophils, and basophils are produced in excess due to a mutation caused by ionizing radiation or fusion protein BCR-ABL gene.

Excessive tyrosine kinase receptor activity inhibits apoptosis, leading to cell survival and continuous replication with DNA mutations over time.

Acute vs. Chronic Leukemia

Acute leukemia progresses rapidly with rapid cell division, while chronic leukemia is a slow progressive process where cells divide but do not die.

CML has three phases: chronic phase (often asymptomatic), accelerated phase, and blast phase.

Symptoms and Diagnostic Indicators

In the chronic phase of CML, patients may be asymptomatic or present with vague symptoms such as leukocytosis without specific symptoms.

Splenomegaly can occur due to leukocyte deposition in the spleen, leading to compression of nearby organs like the stomach causing nausea, vomiting, poor appetite.

Splenomegaly in Chronic Myeloid Leukemia

This section delves into splenomegaly as a common feature in chronic myeloid leukemia (CML) and its impact on the body.

Effects of Splenomegaly

Leukocytes depositing into the spleen can cause splenomegaly leading to symptoms like nausea, vomiting, anorexia due to compression on adjacent organs.

Understanding the Phases of Chronic Myeloid Leukemia

In this section, the speaker discusses the phases of chronic myeloid leukemia, focusing on the chronic and accelerated phases, their characteristics, and key differences.

The Chronic Phase

The chronic phase is where most individuals spend a significant portion of their lives with minimal symptoms.

Symptoms in this phase may include splenomegaly and constitutional symptoms but are often asymptomatic.

Blast cells are low in number (less than 10 percent) while granulocytes are abundant.

The Accelerated Phase

Triggered by a 9;22 translocation leading to increased cell proliferation and decreased apoptosis.

Additional mutations can increase blast cell production (10 to 19 percent), leading to bone marrow occupancy issues.

Decreased red blood cells and platelets due to blast cell proliferation result in anemia and bruising/bleeding tendencies.

Differential Features Between Phases

Thrombocytosis is common in the chronic phase, while thrombocytopenia manifests in the accelerated phase due to blast cell expansion.

Anemia becomes evident in the accelerated phase with features like pallor, dyspnea, and fatigue.

Understanding Chronic Myeloid Leukemia Progression

In this section, the progression of chronic myeloid leukemia (CML) from the chronic phase to the blast phase is discussed, highlighting key changes and risks associated with each stage.

The Accelerated Phase

In the accelerated phase of CML, splenomegaly worsens significantly due to increased deposition of white blood cells in the spleen, leading to a high risk of splenic rupture.

Transition to Blast Phase

Transitioning from the chronic phase to the accelerated phase results in a worsening condition as more myeloid stem cells proliferate, occupying bone marrow and causing bone pain.

The increase in blast cells (10-19%) in the bone marrow leads to bone pain and resembles features of acute leukemia with anemia, thrombocytopenia, and high blast cell count.

The Blast Phase

Progressing into the blast phase signifies a transition from CML to acute myeloid leukemia (AML), characterized by over 20% blast cells due to mutations hindering differentiation capacity.

Accumulated mutations impair cell differentiation, resulting in a proliferation of blast cells (>20%), indicative of AML with high mortality rates.

Impact on Disease Progression

This section delves into how mutations affect disease progression in CML, leading to decreased differentiation capacity and an increase in blast cells.

Mutation Effects

Mutations hinder differentiation beyond pro-myelocytes or metamyelocytes stages, preventing functional white blood cell formation and increasing blast cell presence.

Complications in Advanced Phases

Advancement into later phases exacerbates symptoms such as bone pain, anemia, thrombocytopenia, and increased risk of infections due to fewer functional white blood cells and higher blast cell counts.

Elevated blast cell levels pose risks for oncologic emergencies like leukostasis and tumor lysis syndrome along with common infections such as pneumonia and UTIs.

Recap: Understanding CML Phases

A recapitulation of CML phases emphasizing symptom progression from asymptomatic chronic phase through accelerated and blast phases towards acute leukemia characteristics.

Chronic Phase Recap

Initial chronic phase presents mildly symptomatic with splenomegaly and leukocytosis but low blast cell count; minimal infection risk due to functional white blood cells production.

Disease Evolution

Disease evolution involves mutation accumulation reducing white blood cell functionality while increasing basophils causing itchiness; progressing splenomegaly leads to complications like anemia and thrombocytopenia.

Acute Leukemia Transformation

Understanding Chronic Myeloid Leukemia (CML) Phases

In this section, the speaker discusses the different phases of Chronic Myeloid Leukemia (CML) and how to diagnose them based on specific blood cell counts.

Diagnosing CML Phases

Patients in the chronic phase of CML typically have a normal red blood cell count, while those in the advanced phases may exhibit low red blood cell counts, indicating anemia.

Platelet counts vary in different phases of CML. In the chronic phase, patients may have high platelet counts (thrombocytosis), but as the disease progresses to the accelerated or blast phase, platelet numbers decrease.

White blood cell counts are crucial for diagnosing CML phases. In all phases, especially in the blast phase, there is a significant increase in white blood cells, particularly basophils.

Peripheral Blood Smear Findings

The presence of blast cells on a peripheral blood smear can indicate disease progression. In the chronic phase, granulocytes dominate with few blast cells. However, in advanced phases like accelerated or blast phase, blast cells become more prominent.

Identifying blast cells on a peripheral blood smear can help differentiate between chronic and advanced phases of CML. More blast cells suggest an accelerated or blast phase, while fewer indicate the chronic phase.

Bone Marrow Biopsy for CML Diagnosis

This section delves into using bone marrow biopsies to confirm a diagnosis of Chronic Myeloid Leukemia (CML) and distinguish between its various phases.

Bone Marrow Biopsy Analysis

A bone marrow biopsy aids in confirming a suspected diagnosis of CML by examining cellular composition. Presence and quantity of blast cells help categorize patients into chronic, accelerated, or blast phase CML.

Quantifying blast cells from bone marrow samples is crucial; less than 10% indicates chronic phase CML, 10 to 19% suggests accelerated phase CML, and over 20% signifies blast phase CML.

Differentiating features seen in bone marrow samples such as functional appearing granulocytes like myelocytes and metamyelocytes are indicative of CML rather than Acute Myeloid Leukemia (AML).

Understanding Bone Marrow Biopsy in CML Diagnosis

In this section, the speaker discusses the significance of bone marrow biopsy in diagnosing Chronic Myeloid Leukemia (CML) and differentiating it from Acute Myeloid Leukemia (AML).

Importance of Blast Cells and Differentiation Process

Bone marrow biopsy crucial for detecting blast cells and quantifying them to determine disease stage.

Differentiation level of granulocytes aids in distinguishing between CML and AML.

Determining CML Phase

Assess blast cell count to identify disease phase.

Confirm presence of 9;22 translocation through chromosomal analysis for treatment decisions.

Treatment Decisions Based on Genetic Analysis

Detection of 9;22 translocation guides tyrosine kinase inhibitor therapy selection.

Utilize PCR to quantify BCR-ABL fusion gene for tailored treatment plans.

Distinguishing CML from Leukemoid Reaction

This segment focuses on differentiating Chronic Myeloid Leukemia (CML) from leukemoid reactions based on white blood cell counts and specific markers.

White Cell Count Variations

High white cell count can indicate either CML or leukemoid reaction due to infection or stress.

Specific Marker: Leukocyte Alkaline Phosphatase

Low levels of leukocyte alkaline phosphatase suggest CML, while high levels are indicative of leukemoid reactions.

Diagnostic Imaging and Spleen Enlargement in CML

This part delves into the role of diagnostic imaging, particularly ultrasound or CT scans, in confirming splenomegaly as a common feature in Chronic Myeloid Leukemia (CML).

Diagnostic Imaging for Splenomegaly Confirmation

Perform abdominal ultrasound or CT scan to visualize enlarged spleen, a hallmark feature of CML.

Treatment Approaches for CML

The speaker elaborates on the treatment strategies for Chronic Myeloid Leukemia (CML), emphasizing the importance of targeting the 9;22 translocation that leads to BCR-ABL fusion protein production.

Targeted Therapy Based on Genetic Abnormality

Treatment of Chronic Myeloid Leukemia (CML)

In this section, the speaker discusses the primary treatment for all stages of Chronic Myeloid Leukemia (CML) and delves into the mechanism of action of tyrosine kinase inhibitors in treating CML.

Mechanism of Tyrosine Kinase Inhibitors

The most commonly used tyrosine kinase inhibitor for CML is imatinib, also known as "tanib," which inhibits the BCR-ABL fusion protein.

The BCR-ABL fusion protein leads to hyperactivation of the tyrosine kinase receptor, promoting cell proliferation and inhibiting apoptosis.

Tyrosine kinase inhibitors bind to the BCR-ABL fusion protein, preventing hyperactivation of the receptor and subsequent cell proliferation. This action induces apoptosis in CML cells.

Treatment Options Beyond TKIs

If patients fail tyrosine kinase inhibitors, a bone marrow transplant may be considered as an alternative treatment option.

Cyto-reduction, particularly using hydroxyurea, is another approach for managing symptomatic high white blood cell counts or platelet counts in CML patients when TKIs are ineffective.