הוראה בנושאי טיפול תרופתי בסרטן

1. הוראה בנושאי טיפול תרופתי בסרטן מנגנוני פעולה ועמידות: Hormone therapy, cytokines, targeted therapy, and other investigational therapies ערך: פרופ’ נ. חיים , מאי2004, עודכן אוקטובר 2005 כתובת לשאלות והערות: n_haim@rambam.health.gov.il

2. Hormone therapy in breast cancer • Antiestrogens…. • Progestins….

3. Antiestrogens • Block estrogen action by inhibiting estradiol binding to the ER. • Examples: -Tamoxifen: the tamoxifen-bound receptor exhibits both estrogen agonist and antagonist properties. -Selective ER modulators (SERMs), e.g. Raloxifene (Evista) -Faslodex….. Contd

4. Fulvestrant (Faslodex) Classified as a “pure antiestrogen”: functions by destroying the estrogen receptors (unlike tamoxifen does not have an agonist effect).

5. Progestins • Indirect action on the hypothalamus-pituitary axis consisting of inhibition of gonadotropin-releasing hormone release. • Direct action resulting in the inhibition of cellular proliferation. • Examples: -Medroxyprogesterone acetate (Provera) -Megestrol acetate (Megace)

6. Hormone therapy in breast cancer Aromatase Inhibitors: • Selective aromatase inhibitors…. • Aminogluthetimide….

7. Selective Aromatase Inhibitors-mechanism of action • In postmenopausal women the majority of estrogen is produced by aromatization of adrenal androgens in the peripheral tissues, such as fat and muscle. • The conversion of androstenedione to estrone in the peripheral tissues is catalyzed by aromatase, a complex enzyme consisting of cytochrome P-450 (CYP450) and a flavoprotein. • Conversion of androgens to estrogens is the rate-limiting step in the biosynthesis of estrogens. • Selective aromatase inhibitors compete with androgens for binding to the enzyme (competitive) or bind to the enzyme irreversibly (non competitive). Contd

8. Selective Aromatase Inhibitors-mechanism of action (Contd) Non steroidal=Type II=reversible: • Anastrazole (Arimidex) • Letrozole (Femara) Steroidal=Type I=irreversible: • Exemestane (Aromasin) Smith IE and Dowsett M. N Engl J Med 348: 2431-42, 2003 (Review)

9. Aminogluthetimide Aminogluthetimide is a non selective aromatase inhibitor. Although it inhibits aromatization of androgens to estrogens, its main action is inhibition of adrenal steroidogenesis at early steps (inhibition of the synthesis of aldosterone, cortisol ,and androgenes).

10. Hormone therapy in prostatic cancer • Androgens…. • Anti-androgens…. • Ketoconazole…. • LHRH analogues….

11. Androgens Possible anti-tumor effect in breast cancer: inhibition of gonadotropin-relrasing hormone (negative biofeedback), and , therefore, inhibition of estrogen production.

12. Anti-androgens Steroidal anti-androgens: • Inhibition of nuclear androgen binding; • Suppression of gonadotropin production by a negative biofeedback mechanism and , therefore, suppression of gonadal androgen production. • Example: cyprosterone acetae (predominant activity=competitive inhibition of androgen at the receptor level). (megestrole acetate-a progestational compound- also inhibit androgen production via a negative feedback production, and , therefore, act as anti-androgen). Contd

13. Anti-androgens (Contd) Non-steroidal anti-androgenes: • Do not suppress gonaotropins and testosterone production, but are specific inhibitors of nuclear androgen binding (bind to cytosol androgen receptors and competitively inhibit binding of androgenes). • Examples: -Flutamide (Eulexin) -Bicalutamide (Casodex)

14. Ketoconazole High doses inhibit gonadal and adrenal steroidogenesis by inhibiting the P-450-dependent enzyme system.

15. Luteinizing hormone-releasing hormone (LHRH) analogues • Gonadotropin hormone-releasing hormone (GHRH) is responsible for the synthesis and release of the pituitary hormones, LH and FSH. • Initial stimulatory phase, which is associated with depletion of pituitary LH stores. Initial rise in LH and testosterone, which lasts for approximately 7 days, followed by progressive decrease in the hormone levels, reaching nadirs after approximately 4 weeks. • Examples: -Goserelin (Zoladex) -Leuprolide acetate

16. Cytokines Cytokines: • Interferon alpha…. • Interleukin 2….

17. Cytokines • Soluble proteins or glycoproteins produced by mononuclear cells of the immune system that have regulatory actions on other cells of the immune system or target cells involved in immune reactions • True hormones, acting on other cells at a distance from the secretory cells

18. Interferon alpha • Direct effects: antiprolifetrative and differentiating • Composite: results in alterations in tumor cell surface antigen expression. • Indirect: effects on immune system and antiangiogenic effect

19. Interleukin 2 • Induction of activated T-cell proliferation • Stimulation of cytotoxicity in NK and T cells • Acting as cofactor in activating macrophages and B cells

20. Targeted therapy-Monoclonal antibodies: • Trstuzumab (Herceptin)…. • Rituximab (Mabthera)…. • CAMPATH-1H (Alemtuzumab)…. • Bevacizumab(Avastin) …. • Cetuximab (Erbitux)….

21. Trastuzumab (Herceptin) • HER= human epidermal growth factor receptor • HER2 proto-oncogene encodes the HER2 receptor • The HER2 protein is a transmembrane thyrosine kinase that is a member of the epidermal growth factor. • HER2 is overexpressed in 20-30% of human breast cancers (in the majority, HER2 overexpression is usually caused by amplification of the HER2 gene). HER2 is involved in cell differentiation and growth. HER2 positive tumors have poorer prognosis. Contd

22. Trastuzumab (Herceptin) (Contd) Herceptin is humanized anti-HER2 MAB (95% human and 5% murine). It binds with the extracellular domain of the HER2 cell-surface receptor, thereby inhibiting the growth of breast tumor cells that over express HER2. Tumors strongly overexpressing HER2 (IHC 3+) and/or with proven HER2 gene amplification (FISH positive) are most responsive to herceptin.

23. Rituximab (Mabthera) CD20 antigen: • It is present in high levels on over 95% of B-cell non-Hodgkin’s lymphoma cells. • It is absent from critical host cells such as stem cell or early B-cell precursors. • The antigen does not internalize, is not shed from the cell surface, and does not circulate as free protein. • Evidence suggests that it has a biological function. Contd

24. Rituximab (Mabthera) (Contd) • Rituximab is a genetically engineered chimeric murine/human monoclonal antibody (containing human IgG1 immunoglobulin constant regions and murine variable regions specific for CD20) directed against the CD20 antigen. • Proposed mechanism of action: Antibody-dependent cell-mediated cytotoxicity (ADCC), Complement-dependent cytotoxicity (CDC), Antibody-dependent phagocytosis, Direct antibody effects on CD20 ligation, and induction of apoptosis. • It acts synergistically with chemotherapy.

25. Y(90)-ibritumomab (Zevalin) • Zevalin is the first radioimmunotherapy for advanced refractory lymphoma. • It comprises ibritumomab (a murine IgG1 ANTI-cd20 mAb), covalently linked to the radioisotope yttrium-90 (pure beta-emitter, with half-life of 64hr and a median path length of ~5 mm in soft tissue. Hagenbeek A, and Levington V. Ann Oncol 16: 786-92, 2005

26. I-131-Tositumomab Tositumomab is a murine IgG2a monoclonal antibody that selectively bind to CD20 on the surface of normal and malignant B cells. It can be labeled with iodine 131 to yield I-131-labeled tositumomab. The actions of I-131 tositumomab depend on ionizing irradiation from the decaying I-131 and on the antibody-mediated effects. Kaminski MS et al. N Engl J Med 352: 441-9, 2005

27. CAMPATH-1H (anti-CD52 monoclonal antibody) (Alemtuzumab) • CD52 is cell surface antigen on lymphocytes & monocytes. • Campath is a humanized immunoglobulin G1 (IgG1) anti-CD52 monoclonal antibody that binds to the cell membrane of greater than 95% of all normal human blood lymphocytes , as well as to most B-and T –cell lymphomas. • Active in pts with advanced and chemotherapy resistant CLL. Osterborg A et al. J Clin Oncol 15: 1567-74, 1997 Frampton JE et al. Drugs 63: 1229-43, 2003

28. Avastin (Bevacizumab) • VEGF (vascular endothelial growth factor) , a diffusible glycoprotein produced by normal and neoplastic cells ,has been shown to have central role in the control of angiogenesis and to be essential for the development of tumor vasculature. • VEGF binding to its receptor leads to receptor dimerisation, autophosphorylation of VEGF receptor and cascade of downstream signaling. • Avastin is a humanized anti- (VEGF) monoclonal antibody. It binds to VEGF (ligand) and prevents the interaction of VEGF to its receptors. (In addition to its direct antiangiogenic effects, avastin may also improve the delivery of chemotherapy by altering tumor vasculature and decreasing the elevated interstitial pressure in tumors)(Midgley R, and Kerr D. Ann Oncol 16: 999-1004, 2005)(review)

29. Cetuximab (Erbitux) • Epidermal growth factor receptor is a transmembrane glycoprotein that plays an essential role in the cell growth, differentiation and survival of healthy tissues. • In malignant tissue its activation can reduce apoptosis and facilitate cell proliferation, angiogenesis, and tumor cell migration. • The EGFR comprises an extracellular ligand-binding domain and intracellular tyrosine kinase domains. Binding of specific ligands to the EGFR such as EGF and transforming growth factor alpha (TGF-alpha), results in the dimerisation of the receptor either with another EFGR (homodimerisation) or another member of the EGFR family (heterodimerisation) and a subsequent cascade of intracellular signaling pathways. Phosphorylation of the tyrosine kinase domains is an integral part of signal transduction. contd.

30. Cetuximab (Erbitux)-contd. A recombinant, human/mouse, chimeric monoclonal antibody (IgG1) that binds to the extracellular domain of the human epidermal growth factor receptor (EGFR) and competitively inhibits endogenous ligand binding.

31. Targeted therapy-Epidermal growth factor receptor antagonists-low molecular weight inhibitors: • ZD1839 (Iressa)…. • Erlotinib (Tarceva)….

32. Low-molecular weight inhibitors of the receptor`styrosine kinase • The epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor of the ErbB family (= type I receptor tyrosine kinases=ErbB receptors) that is abnormally activated in many epithelial tumors. • This receptor family is comprised of the following 4 related receptors, that trigger downstream signaling pathways: HER1, HER2/neu,HER3, HER4. • EGFR is a 170-kd transmembrane glycoprotein with an extracellular ligand-binding domain, a transmembrane segment and intracellular component. Activation takes place following ligand binding; the receptors dimerize with either another EGFR (homodimerization) or another member of the EGFR family (heterodimerization). Dimerization results in cross-phosphorylation of the C-terminal tyrosine kinase domains, leading to activation of various EGFR signaling pathways…contd

33. Low-molecular weight inhibitors of the receptor`styrosine kinase-contd • Low-molecular weight tyrosine kinase inhibitors interfere with with receptor signaling by competing with ATP for binding to the tyrosine kinase portion of the receptor. Mendelsohn J and BaselgaJ. J Clin Oncol 21: 2787-99, 2003(Review)

34. ZD1839=Gefitinib (Iressa),& Erlotinib (Tarceva) • HER= human epidermal growth factor receptor • HER1 (EGFR) activation starts a signal-transduction cascade that promotes tumor cell proliferation and has an important role in the survival and growth of many types of cancer. • Iressa & Tarceva are small molecules that selectively inhibits HER1 tyrosine-kinase (HER1-TKI).

35. Targeted therapy-Imatinib (STI571) (=Glivec) • ….

36. Imatinib (STI571) (=Glivec) GIST: • Kit is a 145-KD transmembrane glycoprotein-a product of the c-kit gene. The proto oncogene is type III receptor tyrosine kinase (structurally related to PDGFs and M-CSF). • C-Kit is a mutated KIT receptor overexpressed in certain malignancies such as Gastrointestinal Stromal Tumors (GIST). It has tyrosine kinase activity. Contd

37. Imatinib (STI571) (=Glivec) (Contd) • Kit mutation results in ligand independent activation of KIT tyrosine kinase activity and stimulation of downstream signaling pathways including MAP kinase, P13kinase and STAT pathways. • Imatinib (STI571) is 2-phenylaminopyrimidine derivative. • Imatinib inhibits tyrosine kinase activity of c-kit ,which is activated in GIST as a result of gene mutation (Imatinib is a small molecule TKI (=tyrosine kinase inhibitor)). Heinrich MC et al. J Clin Oncol 20: 1692-703, 2002 (review) Contd

38. Imatinib (STI571) (=Glivec) (Contd) CML: The mechanism of action is due to inhibition of the Bcr-Abl tyrosine kinase created by the Philadelphia chromosome abnormality in CML.

39. Thalidomide • ……

40. Thalidomide • Antiangiogenic effect • Immunomodulatory effects: stimulation of cytotoxic T-lymphocyte proliferation, induction of secretion of interferon-gamma and interleukin-2, modulation of natural-killer cell activity….& other….

41. Other investigational therapies • Farnesyltransferase inhibitors…. • Telomerase inhibitors…. • Antisense oligonucleotides…. • Cyclin-dependent kinase inhibitors.... • Gene therapy….

42. Farnesyltransferase inhibitors • Farnesyltransferase transferase is an enzyme that transfers farnesyl isoprenoid,an intermediate in cholesterol biosynthesis, to certain proteins that associate with cell membranes such as ras proteins (and regulate many physiologic processes). • To be active, the protooncogene ras must be associated with cell membrane. This depends on its farnesylation. • Farnesyltransferase inhibitors may have a cytotxic effect.

43. Telomerase inhibitors • Telomers are specialized nucleoprotein structures at the chromosome ends…..gradually shorten with every cell division unless they are actively maintained. Telomerase is an unusual reverse transcriptase that contains an RNA molecule as well as various protein subunits. • Activation of telomrerase is necessary for cells to become immortal. It is expressed in most human cancers but not in normal somatic tissues. • Telomerase inhibitors may have an antitumoral effect.

44. Antisense oligonucleotides • Antisense oligonucleotides are complementary nucleic acids fragments that hybridize to target sequences within RNA to form DNA-RNA complex, resulting in a block of translation of messenger RNA into the protein, thus blocking the expression of spesific genes.

45. Cyclin-dependent kinase inhibitors • The cell cycle is regulated by the cyclin/cyclin-dependent kinase (CDK) complexes. These CDKs regulate the transition from one cell cycle to the next. • CDKs have been targeted for drug discovery.

46. Gene therapy • Introduction of a therapeutic gene into a target of cell to correct a genetic error or provide a new biologic function to the cell. The vectors used to transfer the gene can be retroviral, adenoviral, and non viral. • Examples: genes that code for cytokines, tumor antigens, MDR, and “suicide “ genes.

47. Proteasome inhibitors • The 26S proteasome is a large intracellular adenosine 5’-triphosphate-dependent protease that identifies and degrades proteins tagged for destruction by the ubiquitin system. • The orderly degradation of cellular proteins is critical for normal cell cycling and function, and inhibition of the proteasome pathway results in cell-cycle arrest and apoptosis. • Bortezomib is the first inhibitor to enter clinical studis. Rajkumar VC et al. J Clin Oncol 23: 630-9, 2005 (review) see also: Mani A and Gelmann E. J Clin Oncol 23: 4776-89, 2005 (review on the role of the ubiquitin-proteasome pathway and its role in cancer)

48. Bisphosphonates • ….

49. Bisphosphonates • Bisphosphonates are analogs of pyrophosphates in which a carbon atom replaces the central oxygen atom (and , therefore, the two phosphate groups are linked to the central carbon atom). • The P-C-P moiety of bisphosphonates is responsible for their strong affinity for divalent atoms, such as calcium ions, and for the skeleton.Contd

50. Bisphosphonates (Contd) Antiresorptive properties: Inhibit osteoclastic bone resorption (lead to osteoclast inactivation, diminish osteoclast maturation, inhibit movement of osteoclasts to the bone surface where they resorb bone, induce apoptosis of osteoclasts) and therefore, reduce the occurrence of pathological fractures, bone pain, hypercalcemic episodes, and the need for radiation therapy and surgery in patients with osteolytic bone metastases. Contd