1. Acute Promyelocytic Leukemia (APL)By
Maged Abd El Fattah Amine
Assistant Lecturer Of Medical Oncology
South Egypt Cancer Institute
3.2014

2. Outline: - Hematopoiesis. - Introduction and Epidemiology of APL
*Outline: - Hematopoiesis. - Introduction and Epidemiology of APL. - Pathogenesis of APL. - Diagnosis of APL. - Treatment of APL. - Conclusions.
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3. Hematopoiesis
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4. - Hematopoiesis is a term describing the formation and development of blood cells. - The hematopoietic system must have the capacity for self renewal, which involves: 1- Proliferation of progeny stem cells. 2- Differentiation and maturation of the stem cells into the functional cellular elements. - Normally hematopoiesis is limited to the bone marrow and the widespread lymphatic system and only mature cells are released into the peripheral blood.
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6. - All cells are derived from a pool of stem cells that are self-renewing. - Pluripotential & multipotential stem cells give rise to committed stem cells for each cell line. - Committed stem cells have receptors for specific growth factors, respond to stimulation by division & maturation (precursor cell stages) into end-stage cells. - Growth factor stimulation increases with need.
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10. Introduction And Epidemiology of APL
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11. - Acute promyelocytic leukemia (APL), is a distinct subtype of acute myeloid leukemia, represents about 10-12% of adult AML cases, and 8% - 15% of pediatric AML. - The median age is approximately years, which is considerably younger than the other subtypes of AML (70 yrs). - It was first described in 1957 by “Hillestad (Sweden)”, as a hyperacute fatal illness. - laboratory evidence of DIC is present in 70% to 90% of patients at diagnosis or shortly after. - Hemorrhagic events contribute 10% to 15% excess mortality during induction chemotherapy for APL.
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12. - Morphologically, it is identified as AML-M3 by the French-American-British (FAB) classification.
- Cytogenetically (WHO), APL is characterized by a balanced reciprocal translocation abnormality, t(15;17)(q22;q12); PML-RARA.
- Currently it is one of the most treatable forms of leukemia with a 12-yr PFS rate, is estimated to be approximately 70%.
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13. Pathogenesis of APL
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14. - In Acute promyelocytic leukemia (APL), there is an abnormal accumulation of immature granulocytes called promyelocytes. - APL is characterized a balanced reciprocal translocation abnormality, t(15;17)(q22;q12); PML-RARA, which results in fusion of the retinoic acid receptor (RARA) gene on chromosome 17 with the promyelocytic leukemia (PML) gene on chromosome The fusion of PML and RARA results in expression of a hybrid protein with altered functions. This fusion protein binds with enhanced affinity to sites on the cell's DNA, blocking transcription and differentiation of granulocytes.
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15. Physiologic quantities of retinoic acid no longer sufficient to allow for cell differentiation.
t(15;17); PML-RARA
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16. - PML/RARa gene product forms homodimer
- PML/RARa gene product forms homodimer. - Homodimer represses target genes needed for differentiation. - Mechanisms act via aberrant histone modification and DNA methylation. - Proliferation via FLT3 and KIT as well are required.
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17. - Although the chromosomal translocation involving RARA is believed to be the initiating event, additional mutations are required for the development of leukemia.
- This translocation abnormality could be detected by karyotyping, FISH or PCR techniques, which is useful for both diagnosis and evaluation of minimal residual disease.
- Eight other rare gene rearrangements have been described in APL fusing RARA to other genes “Variant chromosomal translocations” [e.g., t(11;17), t(5;17)], can be detected in no less than 5% of APL patients.
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19. APL: Molecular Variants
PML-RARa+ insertions 4%
PML-RARa+ variants 2%
PZLF-RARa
t(11;17)(q23,q21)
0.8%
NPM-RARa
t(5;17)(q35,q21)
0.2%
NuMa-RARa
t(11;17)(q13,q21)
< 0.1%
Stat5b-RARa
der(17)
No RARa 1%
APL, acute promyelocytic leukemia; PML, promyelocytic leukemia; RARα, retinoic acid receptor alpha.
There are numerous variants of the disease. In addition to the prototypical variant that leads to the same PML-RAR fusion transcript, accounting for approximately 6% of variants, there are also different fusion partners for the RARα gene, including PZLF, NPM1, NuMa, and Stat5b. However, the resulting fusion proteins are very rarely seen in APL, accounting for < 2% of cases.[4] The significance of these non-PML-RAR transcript variants is that they may sometimes be resistant to all-trans-retinoic acid (ATRA) and even arsenic trioxide (ATO).
PML-RARa
t(15;17)(q22;q21)
92%
4. Grimwade D, et al. Leukemia. 2002;16:

20. Diagnosis of APL
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21. Diagnosis of APL Clinical Morphological Immunophenotyping Cytogenetics
Molecular genetics
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22. Clinical Morphological (Blood & BM) Immunophenotyping Cytogenetics
- S&S of pancytopenia (fever, anemia, bleeding) - Coagulopathy (DIC). - Weakness, and malaise.
- S&S of Organ infiltration.
Clinical
- Abnormal promyelocytes predominate (blasts
may be <20%), packed with granules, numerous Auer rods
in single cell (Hypergranular variant ).
- In M3v, reniform, bilobed nuclei with scant granules.
Morphological
(Blood & BM)
- Classically CD33+, CD13+, MPO+, CD34–, HLA-DR–.
- CD2 and CD34 expression common in microgranular var.
- CD56 in 20% of cases; associated with worse outcome.
Immunophenotyping
- t(15;17)(q22;q12); PML-RARA.
Cytogenetics
- Molecular for PML-RARA needed in rare cases with negative cytogenetics and FISH.
- FLT3 mutations (~30% - 40%); likely adverse effect.
Molecular genetics
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23. # Karyotype: - Detects translocation variant
# Karyotype: - Detects translocation variant. # FISH or immunostaining: - Fast – often within 2-4 hours. - Immunostaining is inexpensive and can be done at smaller centers. # RT-PCR: - Can detect minimal residual disease (MRD). - “Gold Standard”.
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24. Microgranular variant Hypergranular variant
20% of cases
majority of cases
(80%)
Incidence
Leukocytosis
Leukopenia
Clinical Presentation
reniform, bilobed nuclei with scant to
inconspicuous granules
packed with granules, numerous Auer rods
in single cell
Pathology
CD34, is often positive
CD13+, CD33+, MPO+, wCD45+, CD34–,
HLA-DR–
Flowcytometry
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28. Anti-PML Immunofluorescent Antibody Test (“POD” Test)
Sensitivity and specificity of 98.7% and 98.9%
APL, acute promyelocytic leukemia.
The importance of rapid diagnosis in APL is becoming increasingly clear. The disease is highly curable, but only for those patients who receive a timely diagnosis. The anti-PML immunofluorescent antibody (POD), test is performed rapidly, within 3-4 hours. It does not require the typical cytogenetic and molecular testing that is often used to confirm APL diagnosis; and, at least in our hands, it is approximately 99% specific and sensitive.
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5. Dimov N, et al. Cancer. 2010;116:

29. Treatment of APL
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30. Leukemic Infiltration
APL
Leukemic Infiltration
Coagulopathy
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31. Coagulopathy
*Coagulopathy: - It occurs in 70% to 90% of cases. - It occurs due to release of several procoagulants, mainly tissue factor (TF), and cancer procoagulant (CP). # Def: - Fibrinogen level < 150 mg / dl OR 2 of the following criteria; (1) Fibrinogen mg / dl. (2) FDP (D-dimer). (3) PT 3 sec. Longer than control.
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32. # TTT of Coagulopathy: 1- Keep PLT count > 50 000
# TTT of Coagulopathy: 1- Keep PLT count > Maintain fibrinogen level > 150 mg/dl, by FFP 15 ml/kg (max infusion rate = 200 ml/hr) Cryoprecipitate Fibrinogen (2 gm I.V) may be given instead of plasma if available Heparin is of no documented value packed RBCs transfusion may worsen the condition Avoid invasive procedures if possible (leukapheresis, LP, and central line placement).
Note:
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34. 3-yr relapse-free survival
- Using “Sanz” criteria (Sanz score). - Depending on WBCs and Platelets count at presentation.
Risk stratification of APL
3-yr relapse-free survival
Platelet count
WBC count
98%
>40
<10
Low Risk
89%
<40
Intermediate
70%
>10
High Risk
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36. APL Therapy: History HIGHLY FATAL HIGHLY CURABLE
Discovery t(15;17) in APL
ATO frontline
ATRA therapy
First description:
Hyperacute fatal illness associated with hemorrhagic syndrome
Daunorubicin in APL
Differentiation of APL cells with RA
ATO in relapse
ATRA + ATO ± GO
In vivo leukemic cell differentiation
ATRA + CT
APL, acute promyelocytic leukemia; ATO, arsenic trioxide; ATRA, all-trans-retinoic acid; CT, chemotherapy; GO, gemtuzumab ozogamicin.
From its first description and association with hemorrhagic syndrome, APL has been of significant interest to hematologists. In the 1970s, APL was shown to be highly sensitive to anthracycline and associated with the translocation between chromosomes 15 and 17. Beginning in the 1980s, the introduction of ATRA, ATO, and potentially gemtuzumab ozogamicin have revolutionized the treatment of this disease.
HIGHLY FATAL
HIGHLY CURABLE
6. Chen Y, et al. Cancer. 2012;118: Nowak D, et al. Blood. 2009;113:

37. Induction Therapy
TTT of APL
Consolidation
Maintenance
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38. Induction/Consolidation therapy in APL
- Several established treatment protocols offer excellent outcomes. - Important not to “mix and match” induction from one trial with consolidation from another. - ATRA (all-trans retinoic acid) is the cornerstone in each protocol, whatever the risk status. - Treatment must begin before the diagnosis is confirmed in patients with suspected APL, as early ttt is the key for survival.
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40. Treatment of APL
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41. Induction Therapy in APL
# ATRA [Vesanoid Caps.(10 mg)]: - 45 mg/m2 P.O. daily in 2 divided/12hs, till CR or for a max. of days. #Anthracyclines ( DAN or IDA): - Daunorubicin (50 mg/m2 I.V. x 4d), or (60 mg/m2 I.V. x 3d). - Idarubicin (12 mg/m2 I.V. x 2,4,6,8 days). # Cytarabine (Ara-C): 200 mg/m2 CIVI x 7 days, could be added according to the protocol.
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42. Consolidation Treatment in APL
- 2 or 3 cycles of an anthracycline (daunorubicin or idarubicin) plus 1 to 2 weeks of ATRA are administered until molecular CR. - Intermediate- or high-dose Ara-C can be administered depending on age as a first consolidation, as in (GIMEMA, APL 2000 study); or Arsenic Trioxide (ATO) for 2 courses of 25 days each as in (second North American Intergroup C9710 study) To consider LP and IT CTR for 5 doses (weekly) in high risk patients.
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46. Maintenance Treatment in APL
- ATRA and low-dose chemotherapy with 6-mercaptopurine and methotrexate is given for 2 years. -ATRA (45 mg/m2 P.O/day) for 2 weeks every 3 months. - 6-MP (60 mg/m2, P.O/day). - MTX (15 mg/m2, IM/ week). - There is some debate around maintenance ttt in APL, as some studies showed no difference in DFS and OS, but it is still the standard of care till now.
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47. Treatment of APL in Elderly pts
- Elderly patients (> 60y) have poorer outcomes with standard treatment. - In the PETHEMA trial, the last dose of idarubicin was omitted during induction; consolidation should be altered to liposomal ATRA and ATO. - Another option is ATRA + ATO for induction without anthracyclines.
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48. Post- remission Monitoring in APL
1- Document complete molecular remission by PCR after consolidation. 2- Monitor PCR every 3 months up to 2 years. 3- If PCR was –ve, continue maintenance ttt. 4- If PCR was +ve, repeat within 4 weeks to confirm. 5- If PCR still +ve, proceed to ttt of relapse.
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50. Treatment of Relapsed APL
- Arsenic Trioxide (ATO) is the standard ttt of relapsed APL, /- ATRA. - If CR2 and PCR was -ve, consider ASCT, or ATO x 6 cycles. - If PCR was +ve, or No CR, consider AlloSCT or clinical trial, (Gemtuzumab followed by allo SCT). - Strongly consider CNS-directed treatment with intrathecal chemotherapy. - Gemtuzumab ozogamicin (GO) is also an effective agent for patients with relapsed APL. Although this drug is no longer commercially available.
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52. APL syndrome
- "Differentiation syndrome" (formerly known as ATRA syndrome) develops in approximately 25% of patients with APL. - Symptoms of this syndrome are; fever, respiratory distress with pulmonary infiltrates or pleural effusions, and cardiovascular collapse. Temporary pseudotumor cerebri is a fairly common (10%) adverse effect of ATRA. - Although these symptoms most often correlate with leukocytosis (WBC > 10,000/μL), many patients develop symptoms with WBC counts between 5,000/μL and 10,000/μL. The syndrome is seen in patients treated with arsenic trioxide as well as in those treated with ATRA.
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53. (1) Fever + rigors. (2) Capillary leak (dyspnea, pleural effusion, pericardial effusion, HF). (3) CXR: pulmonary infiltrates. (4) Renal failure. (5) Hypotension. (6) Edema & gain of weight. (7) Lymphadenopathy & tonsillitis. (8) Leucocytosis.
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54. # Incidence: Day 2-20 after start of ATRA
# Incidence: Day 2-20 after start of ATRA. #Treatment of this syndrome involves prompt use of: 1- high-dose corticosteroids, Dexamethazone 10 mg I.V. every hrs for at least 3 days, then gradual tapering over 2 ws initiation of conventional Ara-C/daunorubicin chemotherapy to control leukocytosis, and; 3- temporary discontinuation of ATRA or arsenic trioxide. 4- Continue treatment with ATRA after controlling the situation.
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55. Arsenic trioxide adverse effects: - ECG alterations, especially prolongations of the QT interval. - Electrolyte shifts commonly involve potassium and magnesium. potassium should exceed 4mmol/l and magnesium should be above 1.8mg/dl. - Regular ECG checks are indicated. If a QT interval exceeds 500msec therapy will have to be discontinued due to the increased risk of cardiac arrhythmias (torsade de pointes). Any co-medication which might prolong the QT interval in a way similar to ATO should be avoided. - Other frequently occurring, however, not life-threatening adverse effects are nausea, vomiting, exanthema, fatigue, fever, neuropathy, functional liver disorders and increase of transaminase activities, and diarrhea.
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56. Future Directions
# Ongoing trials: - US Intergroup trial S0535,evaluating, Concurrent ATRA, ATO, and GO for induction, then 3 courses of consolidation with daunorubicin plus ATRA, ATO, and GO than maintenance. - GIMEMA[b]/DSIL-APL0406 protocol, which compares ATRA plus ATO with minimal chemotherapy to standard ATRA plus anthracycline. # Two novel agents: - Oral arsenic appears very effective, and the combination with ATRA will be an attractive strategy Tamibarotene (AM-80) that seems less toxic than ATRA .
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57. Conclusions
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58. * Acute promyelocytic leukemia(APL) was first identified as a distinct subtype of acute myeloid leukemia in * APL is characterized by three features; - accumulation of abnormal promyelocytes occurrence of fibrinogenopenia and DIC presence of the specific chromosomal translocation t(15;17)(q22;q21). * Currently it is one of the most treatable forms of acute leukemia (shift from highly fatal to highly curable subtype). * Treatment must begin before the diagnosis is confirmed in patients with suspected APL, as early ttt is the key for survival.
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59. * ATRA (all-trans retinoic acid) is the cornerstone in each protocol, whatever the risk status. * Several established treatment protocols offer excellent outcomes. * Important not to “mix and match” induction from one trial with consolidation from another. * Good supportive care during induction is essential to control DIC and ATRA syndrome.
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60. * To consider evaluation and prophylaxis for CNS involvement after achievement of remission. * Several ongoing trials to evaluate new ttt modalities including low or no CTR . * Novel agents in ttt of APL as Oral arsenic and Tamibarotene (AM-80).
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61. THANK YOU
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