1. Muhammad Qayash Khan PhD in Zoology Ist Semester 2013
Peg-asparginase in the treatment protocol of Acute Lymphoblastic Leukemia
Muhammad Qayash Khan
PhD in Zoology
Ist Semester 2013

2. Leukemia Acute leukemia
Leukemia is a cancer of the marrow and blood.
---The four major types:
Acute Myeloid Leukemia
Chronic myeloid leukemia
Acute Lymphoblastic Leukemia
Chronic lymphocytic leukemia.
Acute leukemia
---A rapidly progressing disease that produces cells (blasts) that are not fully developed.

3. Epidemiology Most common childhood cancer Demographics:
---Males more commonly than females
---Whites more than blacks
---More commonly in patients with Down Syndrome

4. Incidence

5. Etiology and Pathophysiology
ALL stems from mutations
–Radiation
–Chemicals
–Other
Malignant immature white blood cells (WBCs).
–Lymphoblast crowd out the bone marrow.
–This includes crowding out of platelets, RBCs, and mature WBCs.

6. ALL Symptoms Anemia Bleeding and bruising Bone and joint pain Fever
Weight loss
Petechia

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8. Blood and Bone Marrow hematology comparison in ALL

9. Bone Marrow Pathology

10. Etiology… stem cells

11. Symptoms

12. Diagnosis Bone marrow biopsy –>25% lymphoblast in the bone marrow
Lumbar puncture
–CSF cytology
Imaging/scans

13. Pegasparaginase (Oncaspar) for ALL
PEGylated L-asparaginase for the treatment of ALL in patients who are hypersensitive to the native unmodified form of L-asparaginase (obtained from Escherichia coli and Erwinia chrysanthemi). The drug was recently approved for front line use by FDA in 2007.

14. Oncaspar Pegylated L-asparagine amidohydrolase from E. coli.
C1377H2208N382O442S17

15. Pharmacodynamics
The malignant cells are dependent on an exogenous source of asparagine for survival.
Normal cells, however, are able to synthesize asparagine and thus are affected less by the rapid depletion produced by treatment with the enzyme asparaginase. Oncaspar exploits a metabolic defect in asparagine synthesis of some malignant cells.

16. Mechanism of action
Pegaspargase, more effective than native asparaginase, converts asparagine to aspartic acid and ammonia. It facilitates production of oxaloacetate which is needed for general cellular metabolism. Some malignant cells lose the ability to produce asparagine and so the loss of exogenous sources of asparagine leads to cell death.

17. L-Asparaginase – Mechanism of Action
Catalyzes the conversion of L-asparagine to aspartic acid and ammonia.
Reversal of L-asparagine synthetase activity.
Results in rapid and complete depletion of L-asparagine.
Lack of intracellular asparagine results in decrease of protein synthesis and apoptosis.

18. L-asparaginas in Normal Cells

19. L-asparaginase in Tumor Cells

20. L-asparginase action

21. Protein PEGylation

22. Use of Different nanoparticles for drug delivery to the target

23. PEGylation, successful approach to drug delivery
PEGylation is the process of covalent attachment of polyethylene glycol (PEG) polymer chains to another molecule, normally a drug or therapeutic protein..

24. PEGylation
The molecular weight of a molecule increases which impart several significant pharmacological advantages over the unmodified form, such as
Improved drug solubility
Reduced dosage frequency, without diminished efficacy with potentially reduced toxicity.

25. PEGylation Extended circulating life Increased drug stability
Enhanced protection from proteolytic degradation
------PEGylated drugs have the following commercial advantages also:
Opportunities for new delivery formats and dosing regimens
Extended patent life of previously approved drugs

26. Different types of PEGylation

27. L-Asparaginase – Mechanisms of Resistance
Selective pressure of lymphoid cells that overexpress asparagine synthetase gene.
Increase in L-asparagine synthetase due to a decrease in intracellular levels of L-asparagine.
Formation of asparaginase antibodies that alter L-asparaginase pharmacokinetics.

28. L-Asparaginase – Pharmacokinetics
Absorption
Not given orally because of intestinal degradation
Intramuscular administration results in 50% lower peak blood levels than IV route
Distribution
Primarily to intravascular space
Minimal blood-brain penetration
CSF levels are 1% of plasma concentration but depletion of plasma asparagine levels leads to an antileukemic effect in CNS
Metabolism
Not known

29. Half-lives of different L Asparaginase preparations Intramuscular
Elimination
Asselin et al half-life (hours) Dose:25,000 IU i.m
T ½ is variable with dose, disease status, renal or hepatic function, age, or gender
Depends on preparation
PEG-Asparaginase(Oncaspar®) ± 77.8 hours
E.coli L-Asparaginase (Crasnitin®/Elspar®) 29.8 ± 4.1 hours
E. chrysanthemi L-Aspa. (Erwinase®) 15.6 ± 3.1 hours

30. Half-lives of different L Asparaginase preparations intravenous IV
Werber et al. Elimination half life (hours) Dose:10,000IU
PEG-Asparaginase(Oncaspar ®) no data
E.coli L-Asparaginase (Crasnitin ®/Elspar ®) 17.7 ± 2.5 hours
E. chrysanthemi L-Aspa. (Erwinase ®) 7.2 ± 4.1 hours

31. L-Asparaginase – Dosage adjustment
Patients with hepatic impairment
Specific guidelines for dosage adjustments in hepatic impairment are not available
These patients may be at increased risk for toxicity
Patients with renal impairment
Specific guidelines for dosage adjustments in renal impairment are not available
No dosage adjustments are needed

32. L-Asparaginase – Impaired Protein Synthesis
Decreased production of insulin
Resultant hyperglycemia secondary to hypoinsulinemia
Hyperglycemia usually transient and resolves upon discontinuation
Fatal diabetic ketoacidosis has occurred
Patients with diabetes mellitus at increased risk of adverse reactions due to alteration in insulin production or pancreatic insults
Blood sugar should be closely monitored
Decreased production of albumin
Hypoalbuminemia can be severe resulting in peripheral edema or ascites
Patients with limited hepatic synthetic function may be unable to tolerate the effects of L-asparaginase

33. L-Asparaginase – Impaired Protein Synthesis
Decreased production of vitamin K-dependent clotting factors and endogenous anticoagulants such as proteins C and S and antithrombin III
Coagulopathies, thrombosis, or bleeding due to impaired protein synthesis may occur
Monitor coagulation parameters during L-asparaginase therapy
Use cautiously in patients with a preexisting coagulopathy (e.g. hemophilia) or hepatic disease
Intramuscular injections may cause bleeding, bruising, or hematomas due to coagulopathy

34. L-Asparaginase – Toxicities
Mild nausea/vomiting
Anorexia, abdominal cramps, general malaise, weight loss
Tumor Lysis Syndrome (TLS)
Hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia, and decreased urine output
severe renal insufficiency
Appropriate TLS measures must be taken following chemotherapy administration in patients with large chemosensitive tumors
Minor bone marrow suppression effects
Generally transient
Greatest potential is for slight anemia to occur
Marked leukopenia has been reported and white blood cell counts should be monitored

35. L-Asparaginase – Other Toxicities
Hepatic adverse reactions
Elevated AST, ALT, serum alkaline phosphatase, gamma globulin, hyperammonemia, and hyperbilirubinemia or jaundice
Occurs within 2 weeks of starting therapy
Pancreatitis
Caused by necrosis and inflammation of pancreatic cells
Hemorrhagic and/or fatal pancreatitis can occur despite normal amylase and lipase concentrations because of impaired protein synthesis
Pancreatic toxicity is dose-related
Necessitates change of formulation or discontinuation of L-asparaginase therapy

36. L-Asparaginase – Contraindications/Precautions
Contraindicated in patients with history of pancreatitis because of risk of acute pancreatitis.
E. coli preparation is contraindicated in patients with history of anaphylactic reactions to products derived from E. coli sources.

37. L-Asparaginase – Drug Interactions
L-Asparaginase and methotrexate
Therapeutic synergistic and antagonistic effects depend on the schedule of administration
If methotrexate is given 3—24 hours prior to L-asparaginase,
L-asparaginase decreases methotrexate toxicity
Due to blocking the antifolate effects of methotrexate
If methotrexate is given after L-asparaginase, the efficacy of methotrexate is decreased
Due to:
Inhibition of protein synthesis preventing progression to the S-phase of the cell cycle
Blocking of methotrexate polyglutamation
Recommended to give L-asparaginase at least 10—14 days prior to methotrexate or shortly after methotrexate administration
Cells are refractory to methotrexate for up to 10 days following a single dose of L-asparaginase
Period of increased DNA synthesis after L-asparaginase protein inhibition that leads to increased sensitivity to methotrexate

38. L-Asparaginase – Drug Interactions
L-asparaginase and vincristine
If L-asparaginase given concurrently or prior to vincristine, may result in decreased hepatic metabolism of vincristine and cause additive neurotoxicity
Vincristine should be given 12—24 hours prior to L-asparaginase
L-asparaginase and corticosteroids
Result in additive hyperglycemia because L-Asparaginase inhibits insulin production
Insulin therapy may be required in some cases
L-asparaginase and cytarabine
Acute pancreatitis with use of cytarabine in patients that have received prior treatment with L-asparaginase
Anticoagulants, platelet inhibitors, NSAIDs, or thrombolytic agents
Due to the risk of bleeding and coagulopathy during L-asparaginase therapy patients should not receive other agents that may increase the risk of bleeding

39. L-Asparaginase – Monitoring Parameters
Blood glucose
CBC with differential
D-dimer
Fibrinogen
LFTs
Prothrombin time
Serum albumin
Serum creatinine/BUN
Serum uric acid

40. Conclusion and future perspective
Asparaginase is an important component of chemotherapy in ALL treatment protocol.
With pediatric patients the incidence of severeallergic reactions, thrombosis, pancreatitis and hepatic injury are prominent.
The incidence of these toxicities increases with age.
Future perspective……
To reduce the toxicity level and drug efficiency in Adult ALL.

41. References
Dinndorf PAF et al DA drug approval summary: pegaspargase (oncaspar) for the first-line treatment of children with acute lymphoblastic leukemia (ALL). Oncologist. 2007 Aug;12(8):991-8.
AsselinBL,WhitinJC,CoppolaDJ,RuppIP,SallanSE,CohenHJ.Comparativepharmacokineticstudiesofthreeasparaginasepreparations.JClinOncol.1993;11:
0.AlbertsenBK,JakobsenP,SchroderH,SchmiegelowK,CarlsenNT.PharmacokineticsofErwiniaasparaginaseafterintravenousandintramuscularadministration.CancerChemotherPharmacol.2001;48:
1.WerberG.DrugmonitoringvonAsparaginaseimRahmendespädiatrischenTherapieprotokollsderALL/NHL-BFM90Studie.Inaugural-Dissertation,Münster
2.HoDH,BrownNS,YenA,HolmesR,KeatingM,AbuchowskiA,etal.Clinicalpharmacologyofpolyethyleneglycol-L-asparaginase.DrugMetabDispos.1986;14:
3.BoosJ,WerberG,AhlkeE,Schulze-WesthoffP,Nowak-GottlU,WurthweinG etal.Monitoringofasparaginaseactivityandasparaginelevelsinchildrenondifferentasparaginasepreparations.EurJCancer.1996;32A: