Antineoplastic agents selective destruction of malignant tumor cells. Cytostatics. Antineoplastic Agents I. Factors leading to cancer

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Antineoplastic Agents I. Antineoplastic agents selective destruction of malignant tumor cells. Cytostatics Single condition or illness more than 100 different diseases (no wonder drugs).

1 Antineoplastic Agents I. Antineoplastic agents selective destruction of malignant tumor cells. Cytostatics Single condition or illness more than 100 different diseases (no wonder drugs). Biochemical and morpholigical differences between normal and neoplastic cells are slight, they do not arouse an immunological response. Causes: Faulty, unbalanced regulation leads to overexpression of growth factor receptors Failure of cells to undergo apoptosis, no response to DNA damages. (Normal cells: unreparable damage leads to apoptosis.) Invasiveness - tumors do not stay harmlessly in one place, spread to other parts metathesis Factors leading to cancer Viruses (e.g. human papilloma virus uterine cervix, HHV8 Kaposi s sarcoma, hepatitis B liver cancer) Chemical mutagens (e.g. aflatoxin, smoke components, asbestos) Radioactive agents Role and activation of oncogenes Elimination by apoptosis Unregulated multiplication A few carcinogens EGFR A few carcinogens 4 metabolic activation 5 7

2 Types of malignant tumors Solid tumors glandular tissue, epithelium carcinoma, adenoma, melanoma, etc. connective tissue sarcoma (myoma, fibroma) etc. nervous system glioma, neuroblastoma Hematological tumors lymphoma lymphoid leukemia myeloid leukemia Therapy Monotherapy (almost) never used antineoplastics of different mode of actions are combined to overcome resistance. drugs sorted out should have minimally overlapping toxicity. Surgical- and radiotherapy is usually combined with chemotherapy. Intermittent chemotherapy allow healthy cells to regenerate. General side effects (damage of rapidly proliferating tissues): alopecia, leukopenia and neutropenia (bone marrow repression), nausea and vomiting. Antineoplastic agents selective destruction of malignant tumor cells. ld classification: Cytostatics = antineoplastics = anticancer agents comprise the full arsenal of chemotherapeutics against cancer. Cytotoxic agents Recent classification: Cytostatic agents Classification of antineoplastic agents Cytotoxic agents Antimetabolites (inhibition of the DNA synthesis) Alkylating agents (disruption of the function of the DNA) Chelating, complex formating agents inhibition of microtubule assembly (inh. of proliferation) complex formation with DNA (inh. of DNA or topoisomerases) Hormones and antihormones Centrally acting agents (via endocryn system) Blocking of cellular receptors Cytostatic agents MAB and immunoconjugates Small molecule kinase etc. inhibitors Specific supportive, cytoprotective agents 11 Cytotoxic agents lack intrinsic tumor cell selectivity, selectivity relies on rate of proliferation, target basic cell proliferation processes. DNA disruptors (alkylating agents, chain cutters) DNA intercalating agents, topoisomerase inhibitors Nucleotid antimetabolites 12 Cytostatic agents target biochemical processes or specific proteins, which are unique to the tumor cells or are overexpressed compared to the normal cell tumorspecific less toxic side effects Targeted chemotherapy Monoclonal antibodies Tyrosine kinase inhibitors Angiogenesis inhibitors (Antisense and ribozyme therapeutics) 13

3 Antimetabolites Nucleosides Folic acid antagonists Antimetabolites prevent the biosynthesis of compounds necessary in other biochemical processes, in building DNA or they lead to false intermediers and terminate DNA synthesis. purine Folic acid and tetrahydrofolic acid have crucial role in the synthesis of nucleosides THF pyrimidine Folic acid antagonists Folic acid antagonists Purin antagonists Methotrexate Inhibits dihydrofolate reductase. Used against several type of tumors, lymphomas Permetrexed Non-small cell lung carcinoma. The only agant specially used to treat mesothelioma (e.g. asbestosis) Raltitrexed - inhibits thymidilate synthetase. Used to treat colorectal cancers Leucovorin (folinic acid): prevents the lethal effect of inhibition of DHF reductase on normal cells Prodrug of mercaptopurine, provides very long therapeutic concentration by slow hydrolysis. Used mainly for treating acute leukemia. 20 Immunsupressive effect

4 Pyrimidine antagonists Pyrimidine antagonists Basic structures X Fluoro-2 -deoxy-uridylic acid is a competitive inhibitor of thymidylate synthetase leading to the lack of available thymidylic acid. 5-FU is used for the treatment of breast, stomach, colon etc. carcinomas. 23 HN F N This tetrahydrofuranyl derivative is prodrug of 5FU: good oral absorption, coverted back to 5FU in the liver. 24 Contains D-arabinose instead of the usual D-ribose. Two modes of action: 1) After the first phosphorylation it inhibits the cytidylic acid 2 -deoxycytidylic acid converting reductase enzyme. 2) The triphosphate inhibits the DNA polymerase enzyme. Used mainly in the case of different leukemia diseases. Adverse effects: severe leukopenia, anemia. 25 The phosphorilated derivative inhibits the corresponding reductase enzyme, thus the cell is in short of 2 -deoxycytidine phosphate. Used in treatment of adenocarcinomas of the pancreas and non-small cell lung carcinoma, in combination with cisplatine against bladder carcinoma. 26

5 Alkylating agents Very rapid absorption Prodrog of 5-fluorouracil, activated via three enzyamtic steps. Used for the treatment of metastatic breast and colorectal carcinoma, which do not respond well for other agents. Activation of capecitabine Reagents capable to alkylate under physiological conditions nu-h + alkyl-y alkyl-nu + H + + Y - nu = -H, >NH, -NH 2, -SH etc. Y= -Cl, -Br, -S 2 CH 3, epoxydes, aziridinium, tiiranium Selectivity problem. nly DNA should be targeted. Irreversible crosslinking of DNA chains Alkylating agents Synthesis of cyclophophamide Mustards highly toxic compounds used in the 1st WW Gilman and Philips (1946) inhibition of cell proliferation by nitrogen mustard Nitrogen mustards are not active at acidic ph They are the most important antitumor agents, used in acute and chronic myeloid and lymphoid leukemia, lymphomas, and several carcinomas (breast, lung, head, pancreas, etc.), usually in combinations. Selectivity depends on R

6 Cyclophosphamide needs metabolic activation Cyclophosphamide The toxic acrolein (bladder bleeding) can be neutralized with the addition of Mesna (Uromitexan): Nitroso-urea derivatives Unstable compounds that serve very reactive CH 3 + or R-CH 2 + type carbenium ions during activation. Carcinogen compounds, therefore they must be converted to the active agent only at the desired site of action Activation of Carnustine Activation of triazenes Somewhat differently are activated the triazene derivatives Double action: carbamoylation and alkylation

Nitrosourea and triazene derivatives Mitomycin mode of action Nitrosourea and triazene derivatives readily absorb, are quite lipophylic and cross the BBB.

7 Nitrosourea and triazene derivatives Mitomycin mode of action Nitrosourea and triazene derivatives readily absorb, are quite lipophylic and cross the BBB. Indications: different brain tumors (astrocytoma, gliablastoma), malignant melanomas and Hodgkin s disease. Mitomycin antibiotics, Wakiki et al., (1956) from Streptomyces caespitosus. Contains two active sites: carbamoyl and aziridine groups. Indications: adenocarcinomas of stomach, oesophagus, pancreas and bladder Hormones and antihormones Several cell types are dependent on hormonal control. Membrane embedded hormone receptors convert the extracellular signal to the intracellular signal processing system. Neoplastic cells usually retain their receptors and hormone dependency, sometimes hormon receptors are overexpressed. (Tissue sections of breast etc. tumors are always checked for ER and PR receptors by immunohistochemical methods at pathology) (Anti)Hormones do not kill tumor cells but proliferation is inhibited by complex mechanisms Beatson (1896) Estrogens and breast cancer Dr. George Beatson (1896): ovariectomy (removal of the ovaries) causes tumor remission in a subset of patients with MBC. Estrogen binds 1 of 2 estrogen receptors (ERα/ERβ) that function as transcriptional activators to regulate the expression of genes involved in cell proliferation. ver 70% of tumors in women with breast cancer are ER+ and appr. 60% are progesteron, PR+. Hormonal manipulations induce tumor regression in 50-60% of hormone receptor-positive tumors. Hormones Immunohistochemical staining

8 Antiandrogenes Antiandrogens Estrogens Strong antiandrogen activity with very high affinity to the androgen receptors competitive inhibition of the natural substrates testosteron or dihydrotestosteron. Effectively inhibit the proliferation of malignant prostata epithelial cells. riginally developed as nitrogen mustard-type alkylation agent, but it acts as estrogen. Indication: solely prostata carcinoma Antiestrogens Antiestrogens, Tamoxifen Estrogen receptors have two activation domains AF1 and AF2 Tamoxifen attaches to the AF2 domain of estrogen receptors of the tumor cells, which blocks estrogen's effect. AF2 activity is dominant in breast cancer. It is partially agonistic on AF1 elsewhere, such as the uterus or bone protective effect against osteoporosis because it even stimulates the estrogen receptor in bone. Adverse effects of long use: increases the risk of blood clot (thromboembolism) and endometrial cancer. Main indication: postmenopausal breast cancer. Side effects: Hot flushes, sweats, vaginal dryness vaginal discharge. Synthesis of tamoxifen

9 In spite of tamoxifen, fulvestrant destroys estrogen receptors and leads to downregulation. Used for treatment of (recurrent) hormone dependent breast cancer when tamoxifen is not effective. No protective effect against osteoporosis, no effect on Aromatase inhibitors Used for the treatment of postmenopausal hormone dependent breast cancer. Long term (5 years) treatment may promote osteoporosis. Adverse reactions: hot flashes etc. endometrium Aromatase inhibitors Me Me Me Me H NADPH H H NADPH H H H 2 H H 2 H H Androstendion (or testosteron) aromatase NADPH 2 Fe 3+ Me Me H H H H H H H H Estron (or estradiol) Complete block of the biosynthesis of estrogens, which are synthesized after the menopause outside the ovaries. 54 Gestagens Gestagens Gestagens do not bind to estrogen receptors; the activation of progesterone receptors decreases the quantity of ER. Feedback via the hypothalamus decreases the level of FSH (Follicle-Stimulating Hormone) and LH (Luteinizing Hormone) cut down of estrogens and androgens. Hypothalamus GnRH Pituitary LH and FSH Testosterone Testes Estrogens and progesterone varies Modified progesterone derivatives, used in gynecology and in e-pills. Medroxiprogesterone has very long half-life (60 hours) 57

Synthetic GnRH analogues Synthetic GnRH analogues Complex formating agents Inhibiton of microtubule assembly Several alkaloids belong to this group Synthetic nona-decapeptide analogues of the natural

58 Continuous stimulation transient early rise in gonadotropin release pituitary desensitisation, downregulation, leading to suppressed levels of gonadotropins and sex hormones.

10 Synthetic GnRH analogues Synthetic GnRH analogues Complex formating agents Inhibiton of microtubule assembly Several alkaloids belong to this group Synthetic nona-decapeptide analogues of the natural GnRH (gonadotropin releasing hormone) times stronger stimulate the release of FSH and LH than the natural GnRH. 58 Continuous stimulation transient early rise in gonadotropin release pituitary desensitisation, downregulation, leading to suppressed levels of gonadotropins and sex hormones. Indications: advanced prostatic cancer, breast cancer (postadjuvant treatment) endometriosis and precocious puberty. Alkaloid of Colchicum autumnale (meadow saffron) Quite toxic compound Treatment of acute gout myeloid leukemia not used today Depo formulation: 1 inj./month, Diphereline: 3 month Microtubule formation Vinca alkaloids Vinca alkaloids protofilament microtubule α-tubulin β-tubulin tubulin dimer stablize the monomer, inhibit association taxol stabilizes polymer vinca-alkaloids, colchicine centrosoma (MTC) chromosoma Microtubules are tube-like protein structures, serve as structural components within cells and are involved in many cellular processes including mitosis ( mitotic spindle), cytokinesis, and Alkaloids of Vinca rosea (Cataranthus rosea, periwinkle), isolated in Belong to the complicated bisindole family of alkaloids vesicular transport

The semisynthetic vinorelbine is used to treat lung carcinomes. Mode of action: causes depolymerization of microtubules.

11 Vinca alkaloids Taxanes Vincrystine is recommended for leukemia, neuroblastoma, Hodgin- and non-hodgkin lymphomas. It is neurotoxic. Vinblastine is recommended for tumors of the hemopoietic system, testicle tumors (in combination with bleomycin/cisplatin). It has myelotoxicity. The semisynthetic vinorelbine is used to treat lung carcinomes. Mode of action: causes depolymerization of microtubules. 64 Paclitaxel: isolated in small amounts from the bark of Taxus brevifolia (Pacific yew tree) (1971). Semisynthesis from deacetylbaccatin, obtained from the leaves of Taxus brevifolia (European yew tree). Nowadays: plant cell fermentation of a specific taxus cell line. 65 Taxol is approved for (metastatic) non-small cell lung cancer, ovarian cancer, breast cancer, usually in combination with citoxane and epidaunorubicin (TEC) Side effect: strong allergic reactions, hypersensitivity addition of steroids and antihystamines prior to infusion. 66 Microtubule and taxole DNA Complex formating agents Platinum complexes Accidental discovery when investigating the effect of electrical field on E. coli between Pt electrodes (Rosenberg, 1965). Active agent: platinum ammonium complex. Cisplatin: only the cis configuration is active. H3N Cl Pt H3N Cl H 3 N H 2 Pt H 3N Cl + H 3 N H 2 Pt H 3N H 2 2+ H 3 N DNS Pt H 3N DNS Taxol binds to the beta subunit of tubulin and stabilizes the complex. H 3 N Cl - Pt 2+ H 3 N Cl - H 3 N H 3 N Cl Pt Cl Cl H 3 N Pt NH 3 Cl

12 Platinum complexes Cisplatin forms coordinative bonds between N atoms within the range of Å. Crosslinking of DNA (usually within the same chain, GpG) makes impossible for rapidly dividing cells to duplicate their DNA and sets off DNA repair mechanism. Initial phase: Cl - ions exchange with H 2 charged complex interacts with DNA. 70 DNA - cisplatin Platinum complexes Cisplatin: ovarian, testicular and urogenital cancers usually in combination. Adverse effects: nephrotoxicity (hydration!), one of the most emetogenic chemotherapy agents; ototoxicity. Carboplatin: similar to cisplatin with much less adverse effects. Main indications: ovarian and smallcell lung cancer. xaliplatin: combination with 5-fluorouracil and leucovorin for the treatment of colorectal cancers. 73

Cancer Chemotherapy. Munir Gharaibeh MD, PhD, MHPE School of Medicine, The University of Jordan December 2018

Cancer Chemotherapy. Munir Gharaibeh MD, PhD, MHPE School of Medicine, The University of Jordan December 2018 Cancer Chemotherapy Munir Gharaibeh MD, PhD, MHPE School of Medicine, The University of Jordan December 2018 االدوية Polyfunctional Alkylating Agents االستخالبية متعددة الوظائف Not cell cycle-specific.