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group_5_presentation_3_-_chronic_myeloid_leukemia [2017/11/22 22:25] yousis |
group_5_presentation_3_-_chronic_myeloid_leukemia [2018/01/25 15:18] (current) |
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| {{ ::screen_shot_2017-10-01_at_6.19.43_pm.png?525 |}} | {{ ::screen_shot_2017-10-01_at_6.19.43_pm.png?525 |}} | ||
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| + | **Figure 1**: normal blood versus blood of a CML patient. | ||
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| + | Link to PPT presentation: https://docs.google.com/a/mcmaster.ca/presentation/d/1yjxDywKLHAQyuMUwxRe52624DxmA9ek-3qR8e3BM-jw/edit?usp=sharing | ||
| ====== Introduction ====== | ====== Introduction ====== | ||
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| ====== Hierarchy of Blood Cell Development - Hematopoiesis ====== | ====== Hierarchy of Blood Cell Development - Hematopoiesis ====== | ||
| - | <box 38% round right | > {{ ::screen_shot_2017-10-01_at_6.17.34_pm.png?445 |}} </box| Figure X: Development and differentiation of blood stem cells into progenitor cells and fully mature cells.> Hematopoiesis is the process of blood cell development (Smith, Burthem, & Whetton, 2003). Figure x illustrates the development of blood cells in a committed, step-wise fashion (Smith, Burthem, & Whetton, 2003). New cells are continually generated by the proliferation of self-renewing hematopoietic stem cells that give rise to non-self-renewing progenitor cells (Smith, Burthem, & Whetton, 2003). Disruption of this molecular mechanism can lead to the abnormal production of blood cell count (Smith, Burthem, & Whetton, 2003). These progenitor cells are committed to giving rise to cells that are more restricted in differentiation potential and perform a variety of functions. | + | <box 38% round right | > {{ ::screen_shot_2017-10-01_at_6.17.34_pm.png?445 |}} </box| Figure 2: Development and differentiation of blood stem cells into progenitor cells and fully mature cells.> Hematopoiesis is the process of blood cell development (Smith, Burthem, & Whetton, 2003). Figure 2 illustrates the development of blood cells in a committed, step-wise fashion (Smith, Burthem, & Whetton, 2003). New cells are continually generated by the proliferation of self-renewing hematopoietic stem cells that give rise to non-self-renewing progenitor cells (Smith, Burthem, & Whetton, 2003). Disruption of this molecular mechanism can lead to the abnormal production of blood cell count (Smith, Burthem, & Whetton, 2003). These progenitor cells are committed to giving rise to cells that are more restricted in differentiation potential and perform a variety of functions. |
| Hematopoietic stem cells (HSCs) are considered multipotent stem cells, which can differentiate into any blood cell type. Specifically, HSCs give rise to the lymphoid and myeloid lineages of blood cells. The myeloid stem cell gives rise to red blood cells, platelets, and granulocytes (i.e., neutrophils, basophils and eosinophils) while the lymphoid stem cells give rise to B lymphocytes, T lymphocytes, and Natural Killer Cells. | Hematopoietic stem cells (HSCs) are considered multipotent stem cells, which can differentiate into any blood cell type. Specifically, HSCs give rise to the lymphoid and myeloid lineages of blood cells. The myeloid stem cell gives rise to red blood cells, platelets, and granulocytes (i.e., neutrophils, basophils and eosinophils) while the lymphoid stem cells give rise to B lymphocytes, T lymphocytes, and Natural Killer Cells. | ||
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| * **Myelogenous Leukemias**: develop from abnormal myeloid stem cells | * **Myelogenous Leukemias**: develop from abnormal myeloid stem cells | ||
| - | Moreover, the types of leukemia are further grouped based on how quickly the leukemia develops and grows. Acute leukemias start suddenly, developing within days or weeks, and chronic leukemias develop slowly over months or years. The four main types of leukemia are outlined in figure X below. | + | Moreover, the types of leukemia are further grouped based on how quickly the leukemia develops and grows. Acute leukemias start suddenly, developing within days or weeks, and chronic leukemias develop slowly over months or years. The four main types of leukemia are outlined in figure 3 below. |
| {{::screen_shot_2017-11-07_at_4.24.53_pm.png?600|}} | {{::screen_shot_2017-11-07_at_4.24.53_pm.png?600|}} | ||
| - | **Figure X**: Development of the four main types of leukemia | + | **Figure 3**: Development of the four main types of leukemia |
| ====== Signs and Symptoms ====== | ====== Signs and Symptoms ====== | ||
| - | <box 34% round right | > {{ :leukemia.png?375 |}} </box| Figure X: Symptoms of chronic myeloid leukemia.> | + | <box 34% round right | > {{ :leukemia.png?375 |}} </box| Figure 4: Symptoms of chronic myeloid leukemia.> |
| Symptom onset differs depending on the type of leukemia. In acute myeloid leukemia, symptoms develop rapidly, often initially presenting as flu (Sawyers, 1999). However, in chronic myeloid leukemia symptoms develop more slowly, and severity depends on the production levels of unregulated myeloid cells in the bone marrow. Due to the slow progression of the chronic phase, symptoms often develop slowly and diagnosis results from routine blood tests initially performed to diagnose other hypothesized diseases (Sawyers, 1999). | Symptom onset differs depending on the type of leukemia. In acute myeloid leukemia, symptoms develop rapidly, often initially presenting as flu (Sawyers, 1999). However, in chronic myeloid leukemia symptoms develop more slowly, and severity depends on the production levels of unregulated myeloid cells in the bone marrow. Due to the slow progression of the chronic phase, symptoms often develop slowly and diagnosis results from routine blood tests initially performed to diagnose other hypothesized diseases (Sawyers, 1999). | ||
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| === Complete Blood Count (CBC) === | === Complete Blood Count (CBC) === | ||
| - | This is often a routine test showing the number of red blood cells, white blood cells, and platelets in the blood. In a patient with CML, leukocytosis is seen with a remarkable left shift (Quintás-Cardama and Cortes, 2006). This means that there are a high number of immature white blood cells present in the blood, as a result of their early release from the bone marrow. Leukocytosis is most prevalent in basophils and eosinophils. Red blood cells are usually present in less than normal levels, as they are outnumbered by the white blood cells (Sessions, 2007). This usually results in mild anemia. The platelet count may also be slightly elevated, but this case of thrombocytosis does not result in any symptoms directly related to it (Sessions, 2007). | + | This is often a routine test showing the number of red blood cells, white blood cells, and platelets in the blood. In a patient with CML, leukocytosis is seen with a remarkable left shift (Quintás-Cardama and Cortes, 2006). This means that there are a high number of immature white blood cells present in the blood, as a result of their early release from the bone marrow. Leukocytosis is most prevalent in basophils and eosinophils. Red blood cells are usually present in less than normal levels, as they are outnumbered by the white blood cells (Sessions, 2007). This usually results in mild anemia. The platelet count may be less than normal, as the WBC production outcompetes it (Sessions, 2007). |
| {{:cml_blood_smere_.jpg?300|}} | {{:cml_blood_smere_.jpg?300|}} | ||
| - | **Figure x**: CML blood smear showcasing increased WBC count and left shift. | + | **Figure 5**: CML blood smear showcasing increased WBC count and left shift. |
| === Bone Marrow Biopsy === | === Bone Marrow Biopsy === | ||
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| {{:karyotype.gif?300|}} | {{:karyotype.gif?300|}} | ||
| - | **Figure x** : Karyotype showing the translocation of genetic material to produce the Ph chromosome. | + | **Figure 6** : Karyotype showing the translocation of genetic material to produce the Ph chromosome. |
| ====== Molecular Pathogenesis of Chronic Myeloid Leukemia ====== | ====== Molecular Pathogenesis of Chronic Myeloid Leukemia ====== | ||
| - | <box 35% round right | > {{ ::screen_shot_2017-11-10_at_8.57.39_am.png?410 |}} </box| Figure X: Reciprocal translocation of the BCR protein and ABL gene generating an oncogene that constitutively activates unregulated myeloid cell growth leading to CML. > In 1960, Peter Nowell and David Hungerford, working in Philadelphia, described a consistent chromosomal abnormality in patients with CML (Druker, 2008). They consistently reported an acrocentric chromosome that was thought to be a chromosomal deletion (Druker, 2008). Through this discovery, CML became known as the first human malignant disease to be linked to an acquired genetic abnormality (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). | + | <box 35% round right | > {{ ::screen_shot_2017-11-10_at_8.57.39_am.png?410 |}} </box| Figure 7: Reciprocal translocation of the BCR protein and ABL gene generating an oncogene that constitutively activates unregulated myeloid cell growth leading to CML. > In 1960, Peter Nowell and David Hungerford, working in Philadelphia, described a consistent chromosomal abnormality in patients with CML (Druker, 2008). They consistently reported an acrocentric chromosome that was thought to be a chromosomal deletion (Druker, 2008). Through this discovery, CML became known as the first human malignant disease to be linked to an acquired genetic abnormality (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). |
| - | The characteristic genetic abnormality of CML, the Philadelphia chromosome, is present in the bone marrow cells of more than 90% of all patients with CML (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). The reciprocal chromosomal translocation between the long arms of chromosomes 9 and 22, as illustrated below in figure x, is the hallmark of CML (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). This process fuses the Abelson murine Leukemia viral oncogene homolog (ABL) on chromosome 9 with the breakpoint cluster region (BCR) protein on chromosome 22, generating an oncogene that encodes the BCR-ABL protein, a constitutively active cytoplasmic form of the ABL kinase (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). It is this translocation of the two chromosomes and consequent expression of the BCR-ABL kinase that is considered to be the initiating factor in the pathogenesis of CML (Smith, Burthem, & Whetton, 2003). Furthermore, this reciprocal translocation occurs only in somatic cell lines and ultimately, the BCR-ABL fusion kinase leads to increased and unregulated growth of myeloid cells in the bone marrow. | + | The characteristic genetic abnormality of CML, the Philadelphia chromosome, is present in the bone marrow cells of more than 90% of all patients with CML (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). The reciprocal chromosomal translocation between the long arms of chromosomes 9 and 22, as illustrated below in figure 7, is the hallmark of CML (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). This process fuses the Abelson murine Leukemia viral oncogene homolog (ABL) on chromosome 9 with the breakpoint cluster region (BCR) protein on chromosome 22, generating an oncogene that encodes the BCR-ABL protein, a constitutively active cytoplasmic form of the ABL kinase (Kantarjian, Talpaz, Giles, O’Brien, & Cortes, 2006). It is this translocation of the two chromosomes and consequent expression of the BCR-ABL kinase that is considered to be the initiating factor in the pathogenesis of CML (Smith, Burthem, & Whetton, 2003). Furthermore, this reciprocal translocation occurs only in somatic cell lines and ultimately, the BCR-ABL fusion kinase leads to increased and unregulated growth of myeloid cells in the bone marrow. |
| ==== The "Philadelphia Chromosome" ==== | ==== The "Philadelphia Chromosome" ==== | ||
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| {{::cdr533336-750.jpg?475|}} | {{::cdr533336-750.jpg?475|}} | ||
| - | **Figure X:** The reciprocal translocation between chromosome 9 and 22, a hallmark of CML, generating the Philadelphia Chromosome BCR-ABL. | + | **Figure 8:** The reciprocal translocation between chromosome 9 and 22, a hallmark of CML, generating the Philadelphia Chromosome BCR-ABL. |
| ==== Mechanism of Action of the BCR-ABL Fusion Kinase ==== | ==== Mechanism of Action of the BCR-ABL Fusion Kinase ==== | ||
| In vitro analysis has shown that BCR-ABL expression transforms lineage committed HSCs to growth factor independence (Smith, Burthem, & Whetton, 2003). Several downstream signaling pathways are influenced by the fusion of BCR-ABL. The kinase activity of the BCR-ABL oncogene appears to be important in the pathogenesis of CML (Sattler & Salgia, 1997). Of the several signaling pathways activated by BCR-ABL, which include the Ras-Raf-ERK, JAK-STAT, PI3K, JNK/SAPK, NF-κB and c-Myc pathways, the JAK-STAT pathway appears to play a critical role in the maintenance of CML (Fabbro, 2012). | In vitro analysis has shown that BCR-ABL expression transforms lineage committed HSCs to growth factor independence (Smith, Burthem, & Whetton, 2003). Several downstream signaling pathways are influenced by the fusion of BCR-ABL. The kinase activity of the BCR-ABL oncogene appears to be important in the pathogenesis of CML (Sattler & Salgia, 1997). Of the several signaling pathways activated by BCR-ABL, which include the Ras-Raf-ERK, JAK-STAT, PI3K, JNK/SAPK, NF-κB and c-Myc pathways, the JAK-STAT pathway appears to play a critical role in the maintenance of CML (Fabbro, 2012). | ||
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| {{::screen_shot_2017-11-14_at_9.03.56_am.png?600|}} | {{::screen_shot_2017-11-14_at_9.03.56_am.png?600|}} | ||
| - | **Figure X:** | + | **Figure 9**: Normal JAK-STAT pathway versus JAK-STAT pathway of a CML patient, influenced by BCR-ABL. |
| ====== Treatment ====== | ====== Treatment ====== | ||
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| ===Gleevac (Imatinib)==== | ===Gleevac (Imatinib)==== | ||
| - | <box 27% round right | > {{ :gleevac_chart.png?300 |}} </box| Figure X: > | + | <box 33% round right | > {{ :gleevac_chart.png?300 |}} </box| Figure 10: Surival rates of CML patients on Gleevac compared to other therapies> |
| When Gleevec first came out it was called the miracle drug since it seemed as though it was able to cure CML due to its huge success rate. Gleevac works by binding to the closed/inactive conformer of BCR-ABL. This keeps the binding site for ATP closed and thus inhibiting the downstream signaling pathway which contributes to the progression of CML. During one of its first clinical trial conducted by Druker et al (2001), they looked at 54 patients with CML and prescribed them Gleevac of 300mg daily. Out of the 54 patients, 53 had a complete hematologic response within 4 weeks of therapy. A hematologic response is used to measure the recovery process of a CML patients by looking at whether their blood counts have returned back to normal and that there are no more immature cells in the blood. Druker et al (2006) did a 5-year follow-up study and found that after 60 months on Gleevac, 98% of all their patients showed a complete hematologic response. The more outstanding result was that after 60 months the survival rates for patients were 89%. This is a huge improvement since only 30% of patients survived 5 years after being diagnosed with CML. Although within one year of the drug being released, some individuals started showing resistance to the drug due to CML cells having constant exposure to it. However, Gleevac still is the recommended and first line of drug for CML patients. | When Gleevec first came out it was called the miracle drug since it seemed as though it was able to cure CML due to its huge success rate. Gleevac works by binding to the closed/inactive conformer of BCR-ABL. This keeps the binding site for ATP closed and thus inhibiting the downstream signaling pathway which contributes to the progression of CML. During one of its first clinical trial conducted by Druker et al (2001), they looked at 54 patients with CML and prescribed them Gleevac of 300mg daily. Out of the 54 patients, 53 had a complete hematologic response within 4 weeks of therapy. A hematologic response is used to measure the recovery process of a CML patients by looking at whether their blood counts have returned back to normal and that there are no more immature cells in the blood. Druker et al (2006) did a 5-year follow-up study and found that after 60 months on Gleevac, 98% of all their patients showed a complete hematologic response. The more outstanding result was that after 60 months the survival rates for patients were 89%. This is a huge improvement since only 30% of patients survived 5 years after being diagnosed with CML. Although within one year of the drug being released, some individuals started showing resistance to the drug due to CML cells having constant exposure to it. However, Gleevac still is the recommended and first line of drug for CML patients. | ||
| ===Dasatinib=== | ===Dasatinib=== | ||
| - | <box 26% round right | > {{ :gleevac_dasatinib.png?300 |}} </box| Figure X: > | + | After resistance grew on Gleevac, there was a development of another variation of the drug called Dasatinib. Unlike Gleevac, this drug targets the open/active conformer of BCR-ABL by binding to the active site and directly competing with ATP. During Clinical trials it showed it showed promising results. The researchers tested on 670 CML patients and broke them up into 4 groups, which were prescribed varying doses. At the end of their trials, 86-92% of patients saw complete hematologic response (Aguilera & Tsimberidou, 2009). There is research being done on combine drug therapy with Dasatinib and tyrosine kinase inhibitors. They have shown to work synergistically really well in producing growth inhibition and inducing apoptosis in CML cells (Aguilera & Tsimberidou, 2009). Dasatinib is currently used as a form of treatment for CML and is an effective therapy. <box 33% round middle | > {{ :gleevac_dasatinib.png?250 |}} </box| Figure 11: Target binding sites of Gleevac and Dasatinib > |
| - | After resistance grew on Gleevac, there was a development of another variation of the drug called Dasatinib. Unlike Gleevac, this drug targets the open/active conformer of BCR-ABL by binding to the active site and directly competing with ATP. During Clinical trials it showed it showed promising results. The researchers tested on 670 CML patients and broke them up into 4 groups, which were prescribed varying doses. At the end of their trials, 86-92% of patients saw complete hematologic response (Aguilera & Tsimberidou, 2009). There is research being done on combine drug therapy with Dasatinib and tyrosine kinase inhibitors. They have shown to work synergistically really well in producing growth inhibition and inducing apoptosis in CML cells (Aguilera & Tsimberidou, 2009). Dasatinib is currently used as a form of treatment for CML and is an effective therapy. | + | |
| ===Hydrea (Hydroxyurea)=== | ===Hydrea (Hydroxyurea)=== | ||
