UAEU - CMHS - Hematology-Oncology Course - MMH 302 - HONC 320. Education material for medical students - It cover basic principles of hematology and oncology, including CAR-T and gene editing. It can be used for study and review. It illustrates main principles of hematology and oncology.

1. Thrombophilia
9/26/2018 Abdul-Kader Souid
(Thrombosis, Thromboembolic Events, Primary Hypercoagulability)
(1) Aberrant blood vessel
(atherosclerosis) + activated platelets
Myocardial infarction (MI)
Stroke (thrombotic cerebrovascular event)
Arterial thrombosis
(2) ↑Coagulation proteins (↑FV)
(3) ↓Anticoagulation proteins (↓PC)
(4) ↓Fibrinolytic proteins
Venous thrombosis Deep venous thrombosis (DVT)
Pulmonary embolism (PE)
Must know
Fg, fibrinogen
FDPs, fibrin degradation products
TM, thrombomodulin
II, prothrombin
IIa, thrombin
APC, activated protein C
Pg, plasminogen
Pn, plasmin
TAFI, thrombin-activatable fibrinolysis inhibitor
Coagulation & Fibrinolysis

2. Arterial Thrombosis
Abnormal vessel wall
+
Activated platelets
2
Arterial thrombosis
Myocardial infarction (MI)
Thrombotic cerebrovascular event (stroke)
Arterial thrombosis = Platelet adhesion to abnormal vessel wall (atherosclerosis) followed
by platelet activation, aggregation, and recruitment → MI or stoke
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Must know

3. Venous Thrombosis
Primary hypercoagulability
↑Coagulation (↑V, ↑ II, ↑ VIII, ↑ IX, ↑ X, ↑ XI)
↓Anticoagulation (↓C, ↓S, ↓Antithrombin)
↓Fibrinolysis
Spontaneous clots = Homozygosity or double
heterozygosity
Precipitated clots
(1) ↓Blood flow (pregnancy, surgery, long-haul
travel, indwelling catheters, dehydration)
(2) ↑Estrogen (oral contraceptives, pregnancy)
(3) Obesity, diabetes, aging
3
Venous thrombosis
Deep venous thrombosis (DVT)
Pulmonary embolism (PE)
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Must know
Coagulation & Fibrinolysis

4. Fibrinolysis
Coagulation and fibrinolysis exist as a fine hemostatic balance. Thrombin (IIa) is the central
enzyme in coagulation. It cleaves the soluble fibrinogen (Fg) to insoluble fibrin (FN) clot.
Plasmin (PN) is the central enzyme in fibrinolysis. Plasmin is generated from plasminogen (PG)
by the activity of tissue plasminogen activator (tPA). Plasmin digests the insoluble fibrin (FN)
clot into soluble fibrin degradation products (FDPs). The balance between these two systems is
controlled by natural inhibitors of the cascades. Thrombin generation is inhibited by Protein C
(PC). Plasmin generation is inhibited by “thrombin-activatable fibrinolysis inhibitor” (TAFI).
These two regulatory processes are controlled by the trans-membrane “thrombin-
thrombomodulin (II-TM) complex”. Binding of thrombin to thrombomodulin converts its
substrate specificity from promoting fibrin formation to inhibiting plasmin generation.
Must know
Fg, fibrinogen; FDPs, fibrin degradation products; TM,
thrombomodulin; II, prothrombin; IIa, thrombin; APC,
activated protein C; Pg, plasminogen; Pn, plasmin;
TAFI, thrombin-activatable fibrinolysis inhibitor.
Coagulation & Fibrinolysis
Plasminogen Plasmin
Fibrin
FDPs
tPA (activates)
IIa-TM (inhibits)

5. Harrison's Principles of Internal Medicine, 18e > Chapter 117. Arterial and Venous Thrombosis
Table 117–2 Heritable Causes of Arterial and Venous Thrombosis
A. Arterial Thrombosis
Platelet Receptors:
β3 and α2 integrins
PlA2 polymorphism
Fc(gamma)RIIA
GPIV T13254C polymorphism
GPIb Thrombin receptor PAR-1-5061 → D
Redox Enzymes:
Plasma glutathione peroxidase
H2 promoter haplotype
Endothelial nitric oxide synthase: −786T/C, −922A/G, −1468T/A
Paraoxonase: −107T allele, 192R allele
Homocysteine:
Cystathionine β-synthase 833T → C
5,10-methylene tetrahydrofolate reductase (MTHFR) 677C → T
B. Venous Thrombosis
Coagulant Proteins:
Fibrinogen: −455G/A, −854G/A
Prothrombin (20210G → A)
Protein C Anticoagulant Pathway
Factor V Leiden: 1691G → A (Arg506Gln)
Thrombomodulin: 1481C → T (Ala455Val)
Fibrinolytic Proteins with Known Polymorphisms:
Tissue plasminogen activator (tPA): 7351C/T, 20 099T/C in exon 6, 27 445T/A in intron 10
Plasminogen activator inhibitor (PAI-1): 4G/5G insertion/deletion polymorphism at position −675
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Optional
No need to routinely test for: Homocysteine, factor VIII, MHTFR / XIII polymorphism, & PAI-I

6. ↑Coagulation Proteins
↑Factor V half-life
(mutations in factor V causing resistance to
proteolysis by protein C (protein C
resistance)
↑Factor II (Prothrombin mutation
G20210A)
↑Factor VIII, IX, X, XI
6
↓Anticoagulation Proteins
↓Protein C
↓Protein S
↓Antithrombin (strongest risk)
Heritable Thrombosis
(short list)
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↓Plasminogen
↓Fibrinolytic Proteins
Must know
↑Factor V half-life (important)
The screening test is “activated protein C resistance (APC resistance)” Factor V
mutations; eg, Factor V Leiden (= resistant factor V) = G1691A (Arg506Gln)
↑Homocysteine - MTHFR
polymorphism → arterial thrombosis
(weak effect; no need for testing)
No need to routinely test for: Homocysteine, factor VIII, MHTFR / XIII polymorphism, & PAI-I

7. Activated Protein C (APC) Resistance Assay
(An aPTT-based Assay)
Activated partial thromboplastin time (aPTT)
Citrated plasma + phospholipid + Ca2+ + silica → Measure time to fibrin clot
Citrated plasma + phospholipid + Ca2+ + silica + Activated protein C [APC] → ↑Time to
fibrin clot (a normal response to APC)
Citrated plasma + phospholipid + Ca2+ + silica + Activated protein C [APC} → No
change in the time to form fibrin clot (an abnormal response to APC = APC Resistance)
Protein C inactivates factor V.
Factor V Mutations (e.g., Factor V Leiden)
• They are the most common inherited risk factor for thrombosis.
• Mutation causes factor V to become resistant to proteolysis by protein C.
• It affects 5% of the U.S. white population (heterozygous state).
• Individuals who are heterozygous have a 5-fold ↑risk of venous thrombosis
(especially women who are taking oral contraceptives).
• Individuals who are homozygotes have a 100-fold ↑risk of venous thrombosis.
Must know

8. Protein C Deficiency
The anticoagulant Protein C is activated by a thrombin-
thrombomodulin (IIa-TM) complex on the surface of
endothelial cells. Activated protein C (APC) then binds to
protein S and the resulting protease inactivates factor V,
halting thrombin generation. Homozygous Protein C
deficiency presents early in infancy with purpura fulminans
(shown), which is treated with daily protein C (plasma for
protein S deficiency).
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Must know

9. A More Complete Work-up of Thrombosis
9
1. Activated protein C (APC) resistance assay (aPTT-based assay)
2. Factor V Leiden (DNA-based assay, G1691A)
3. Factor II 20210G → A (prothrombin mutation)
4. Protein C & S activity and antigen
5. Antithrombin activity & antigen
6. Homocysteine (blood level)
7. Methyltetrahydrofolate reductase (MTHFR) genetic testing (if ↑homocysteine)
8. Plasminogen activity
9. Tissue plasminogen activator (TPA) antigen
10. Plasminogen activator inhibitor activity (PAI-1)
11. α2–Antiplasmin activity
12. Lipoprotein A (decreases fibrinolysis)
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Optional

10. Vitamin K & Warfarin
• Vitamin K is a fat-soluble vitamin, required for complete synthesis of factors II
(prothrombin), VII, IX, X, Protein C, and Protein S. These six proteins require
vitamin K for the addition of 9-12 γ-carboxyl groups (COO-) at specific glutamate
residues. The resulting carboxylated glutamates mediate Ca2+-dependent binding of
these factors to platelet surface (phospholipids).
• Vitamin K deficiency is caused by (1) Diet short of animal fats (egg yolks, milk, red
meat) and dark green vegetable, (2) Fat malabsorption (biliary obstruction
[cholestasis, direct hyperbilirubinemia], cystic fibrosis), (3) Use of broad-spectrum
antibiotics. Vitamin K deficiency is associated with ↑PT/INR, ↑aPTT, and normal TT.
• Warfarin (coumarin or Coumadin; an anticoagulant) is vitamin K antagonist, which
inhibits the six vitamin K-dependent factors.
• The use of warfarin is challenging because the therapeutic range is narrow (INR =
2.0 to 3.0) and dosing is affected by genetic variation, drug interactions, and diet.
Time spent with a PT/INR above the therapeutic range increases the risk of bleeding,
and time spent below the therapeutic range increases the risk of thromboembolic
complications. Warfarin has a large clinical experience and is highly effective in
reducing the risk of venous and arterial thromboemboli.
Must know

11. Warfarin
• Factor X is the most potent activator of prothrombin and it is the
primary target of anticoagulation by warfarin. Depletion of
factor X prevents prothrombin activation.
• The half-life of factor X is 20-40 h, shorter than that of
prothrombin (60 h). As a result, it takes a few days before the
anticoagulant effects (prothrombin depletion) of warfarin are
fully achieved.
• Thus, for treatment of deep vein thrombosis (DVT), heparin
must be overlapped with warfarin (time to effect = 2-5 days;
half-live about 40 h) for a few days to maintain anticoagulation.
• Reversal of warfarin effect in symptomatic patients include vitamin K (non-
urgent reversal; IV, SC, or oral) and Prothrombin Complex Concentrate (II,
VII, IX, X; for urgent reversal) + vitamain K.
Must know

12. Antithrombotic Agents
Thrombolysis
(recombinant tissue
plasminogen activator, rTPA)
Unfractionated
Heparin
Low Molecular
Weight Heparin
(enoxaparin)
Mechanism
rTPA + Plasminogen →
Plasmin → ↑fibrinolysis
Antithrombin–
dependent
Inactivate Factor X
Indication Threatening thrombi Other thrombi Other thrombi
Dose
IV infusion or injection
directly into the thrombus
IV bolus followed
by infusion
Subcutaneous
every 12 to 24 h
Monitoring ↑D-dimer ↑aPTT
Anti-factor X
activity
Risk of
bleeding
Medium-to-High Low-to-Medium Low
Must know
Warfarin has a large clinical experience and is highly effective in treating
thrombotic events and in reducing the risk of venous and arterial thromboemboli.
The treatment is followed by INR.
Contraindications to thrombolysis include (1) Active bleeding; (2) Intracranial neoplasm; (3) Major
trauma or surgery within 10 days; (4) Severe hypertension; (5) Active seizure; (6) Prematurity (<32
weeks’ gestation); and (7) Platelet count <50 x109/L or fibrinogen <100 mg/dL (2.94 µmol/L).

13. Must Know Pearls
• Activated platelets cause arterial thrombosis.
• ↑Coagulation factor(s) cause venous thrombosis (e.g., ↑factor V, such as factor V Leiden).
– Factor V Leiden = factor V mutation causing resistance to proteolysis by protein C
(Protein C resistance).
• ↓Anticoagulation factor causes venous thrombosis (e.g., ↓Protein C or S).
• ↓Fibrinolytic factor cause venous thrombosis (e.g., ↓plasminogen).
• Antithrombotic therapies include ‘recombinant tissue plasminogen activator’ (rTPA),
warfarin, unfractionated heparin, and low-molecular weight heparin (enoxaparin, inhibits
factor X).
• Avoid oral contraceptives in high-risk thrombotic conditions (positive history of
blood clots).
• Patients with a known risk of thrombosis who are going to be immobilized should
receive prophylactic enoxaparin.

14. Q. A 17-year-old girl presents with left popliteal deep vein thrombosis
(DVT) while taking an estrogen-containing oral contraceptive. Her
maternal family history is positive for DVT.
Which one of the following conditions is the most likely cause of her
precipitated DVT?
A. Protein C deficiency
B. Prothrombin mutation G20210A
C. Antithrombin deficiency
D. Plasminogen deficiency
E. Factor V Leiden (G1691A; Arg506Gln)
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15. Required Reading
1. Monagle P, Chan AKC, Goldenberg NA, Ichord RN, Journeycake JM, Nowak-Göttl U,
Vesely SK. Antithrombotic therapy in neonates and children: Antithrombotic Therapy
and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-
Based Clinical Practice Guidelines. Chest. 2012;141:e737S-e801S. doi:
10.1378/chest.11-2308.
2. Harrison's Principles of Internal Medicine, 18e > Chapter 117. Arterial and Venous
Thrombosis
3. Young G, Albisetti M, Bonduel M, et al: Impact of inherited thrombophilia on venous
thromboembolism in children: a systematic review and meta-analysis of observational
studies. Circulation 118:1373–1382, 2008.
4. Daví G, Patrono C: Platelet activation and atherothrombosis. N Engl J Med
13;357:2482, 2007.
5. Mechanisms of thrombus formation. N Engl J Med 28;359:938, 2008.
6. Tapson VF: Acute pulmonary embolism. N Engl J Med 6;358:1037, 2008.
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16. Connors JM. Thrombophilia Testing and Venous Thrombosis. N Engl J Med.
2017;377:2298. doi: 10.1056/NEJMc1713797.
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17. 9/26/2018 17
Connors JM. Thrombophilia Testing and Venous Thrombosis. N Engl J Med.
2017;377:2298. doi: 10.1056/NEJMc1713797.