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Antineoplastic Agents.  Cancer, one of the major challenges which concern the medical community all over the world. The diversity of tumor types and.

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Presentation on theme: "Antineoplastic Agents.  Cancer, one of the major challenges which concern the medical community all over the world. The diversity of tumor types and."— Presentation transcript:

1 Antineoplastic Agents

2  Cancer, one of the major challenges which concern the medical community all over the world. The diversity of tumor types and the great similarity to normal cells are the main obstacle preventing the reach of an ultimate remedy. Cancers could be classified based on their nature and location throughout the human body into two main categories:  Solid tumors, which found in tissues and organs such as glandular tissue cancers (carcinomas) and connective tissue cancers (sarcomas) which could disseminate to other body parts through the blood circulation and the lymphatic system. Solid tumors are difficult to treat due to the lack of vascularity and blood supply inside the tumor, which prevents any drug from reaching the core of the tumor mass.

3  Malignant hematologic diseases, such as lymphatic ganglia cancers (lymphomas) and blood cancers (leukemias).  The rate of cell division is the only sensible difference (found so far) which distincts cancer cell from normal cell, tumor cell is rapidly proliferating. This rapid proliferation comprises another difficulty in combating cancer. The lack of obvious difference makes it difficult for any chemotherapeutic agent to distinguish between cancer cell and any healthy cell, especially those which are naturally of rapid cell division, as for example bone marrow cells and the mucosa lining the walls of the gastrointestinal tract.

4  Tumors can be classified according to their locations into:  Carcinoma → Glandular tissue cancers.  Sarcoma → Connective tissue cancers.  Lymphoma → Lymphatic ganglia cancers.  Leukemia → Blood cancers.  Cell proliferation is the only difference between normal and cancer cell, cancer cell is rapidly proliferating.  How could the anticancer agents be selectively toxic to cancer cell?  Tumor cell is more rapidly proliferating than normal cell so it will consume more of the drug.  The drug is highly toxic to the organs which is normally rapidly proliferating such as bone marrow, hair, GIT.

5  Anticancer agents could be classified based on type of activity into three main groups:  1) Growth inhibitors: Drugs which inhibit the growth of cancer cells into 50%. GI50: Molar concentration which inhibit net cell growth to 50%. (median growth inhibitory concentration).  2) Cytostatic agents: Drugs which totally inhibit the growth of cancer cells. TGI: Molar concentration which cause total inhibition of cell growth (total growth inhibitory concentration).  3) Cytotoxic agents: Drugs which cause 50% killing of the original no. of cancer cells.  LC50: Molar concentration which cause 50% killing of the initial cell level (median lethal concentration).

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7  It is well established and documented that the difference between normal and cancerous cell lies in the cell nucleus which controls cell division and rather more, it might reach the gene level.  Most of the antineoplastic agents are designed to interfere with the protein synthesis followed by the inhibition of cell vital processes leading to cell death.  Anticancer agents could be classified based on their mode of action into:  DNA Interactive Drugs (DID)  Antimetabolites  Hormones

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9  DNA alkylators are those class of compounds which proved to alkylate the nucleophilic centers at the nucleic acid bases (guanine, thymine … etc.) leading to the formation of deformed DNA which will affect protein synthesis causing cell death.

10  DNA alkylators could be classified into:  Nitrogen mustard and its analogs.  Ethylenimines.  Epoxides.  Sulphonic acid esters.  Miscellaneous.

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12 N,N-Bis-( β -chloroethyl)methylamine HCl N-Methyl-bis(2-chloroethyl)amine HCl  Mechlorethamine is the only aliphatic nitrogen mustard currently on the U.S. market and its use is limited by extremely high reactivity, which leads to rapid and nonspecific alkylation of cellular nucleophiles and excessive toxicity.

13  It is an example of nitrogen mustard containing an aromatic ring.  It is active intact and also undergoes β -oxidation to provide active phenylacetic acid which is responsible for antineoplastic activity.  It is used in chronic lymphocytic leukemia, malignant lymphoma and Hodgkin’s disease.

14 4-[Bis-(2-chloroethyl)amine] phenylbutyric acid. Synthesis

15 N,N-Bis(2-chloroethyl)tetrahydro-2H-1,3,2-oxazaphosphorin-2-amine-2-oxide.  It is a prodrug that requires activation by metabolic and non metabolic process.  This need for metabolic activation means decrease in GI toxicity and less non specific toxicity if compared with other alkylators.

16 Metabolism

17 It is also known as L-phenylalanine mustard or L-PAM, is nitrogen mustard chemically linked to a natural amino acid. It is also attached to aromatic ring so it is less reactive with decreased incidence of side effects. It is used in inoperable malegnancies.

18 DNA 2 Aziridinium cation Intrastrand cross linked DNA Alkylated DNA  cell death

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20 2,4,6-Tris (1-aziridinyl)-s-triazine. Synthesis SOCl 2 +

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23 1,2,3,4-Diepoxybutane Synthesis

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26 1,4-Bis(Methansulphonyloxy)butane. Tetramethylene-bis(methane sulphonate) Busulfan is classified as an alkyl sulfonate; one or both of the methylsulfonate ester moieties can be displaced by the nucleophilic N7 of guanine, leading to monoalkylated and cross- linked DNA.

27  Synthesis

28 Metabolism and Mode of Action DNA Hydroxylation Oxidation +

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30 5-(3,3-Dimethyl-1-triazenyl)-imidazole- 4-carboxamide

31 Metabolism and Mode of Action -N 2 + Cell death

32 N-(Isopropyl)-4-(2-methylhydrazinomethyl)benzamide HCl.

33 Mode of Action H2OH2O DNA + P450 or spontaneous

34  Cisplatin, Platinol: Cis-diaminedichloroplatinum

35  Carboplatin It is a less potent chemotherapeutic agent. Suppression of platelets and white blood cells is the most significant toxic reaction of carboplatin use.

36  Duration of Action:  BCNU: t ½ = 90 min.  CCNU: t ½ = 16 hr.  Nitrosoureas possess high lipid solubility which allows BBB crossing, so they used mainly to treat Brain tumors and Hodgkin’s disease.  Mode of Action: alkylating agents.

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39  Polycyclic plannar compounds have the ability to insert or intercalate through the grooves of the base pairs of the DNA double helix.  This insertion process will activate topoisomerase I & II enzymatic system which catalyzes DNA strand cleavage.  Acridines such as amsacrine proved to possess this DNA intercalation activity.  Figure 1, shows how the tyrosinyl moiety carried by topoisomerases could catalyze such DNA cleavage.

40 9-[(2-Methoxy-4-methylsulphonylamino)aniline]acridine.

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42  Natural products such as bleomycins, mitomycins (7) and streptozotocin (8) are characterized by their ability to intercalate into the DNA duplex and initiate a series of free radical destruction of the DNA strand preventing the process of mitosis and consequently preventing cell division.

43  Those Natural products are: Antibiotics  Bleomycins  Daunorubicins  Mitomycins  Streptozotocin Vinca Alkaloids  Vinblastine  Vincristine

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45  Mode of Action of Strand Breakers Cycle of events involved in DNA cleavage by bleomycin (BLM)

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47 A.Daunorubicin Analogs NADPH Enzyme Anthracycline antitiumor agents as bioreductive alkylators

48 B.Mitomycin analogs 1 or 2 e - 1 or 2 H +

49 RR1R1 R2R2 R3R3 R4R4 VincristineCH 3 COCHOHOHOCH 3 VinblastineCH 3 COCH 3 HOHOCH 3 VinrosidineCH 3 COCH 3 OHHOCH 3 VinleurosineCH 3 COCH 3 H?OCH 3 Vinglycinate(CH 3 ) 2 NCH 2 COCH 3 HOHOCH 3 VindesineHCH 3 HOHNH 2

50  Colchicine, obtained from the crocus Colchicum autumnale, has long been known for its antitumor activity. However, it is not now used clinically for this purpose. Its main use is in terminating acute attacks of gout. Among colchicines derivatives, demecolcine (colcemid) is active against myelocytic leukemia, but only at near-toxic doses. Colchicines have an unusual tricyclic structure containing a tropolone ring. They inhibit mitosis at metaphase by disorienting the organization of the spindle and asters.

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52  Those are class of compounds which are structurally related to natural occurring substances found in normal cells.  Antimetabolites compete with those natural cell components for the active sites on enzyme(s) or receptor(s), and they might incorporate into the nucleic acids to disrupt their cellular functions.  Antimetabolites could be classified into:  Purine Antagonists  Pyrimidine Antagonists  Folic acid Antagonists (Dihydrofolate Reductase Inhibitors= DHFR Inhibitors)

53  Those are group of compounds which are structurally related to the natural purine bases (hypoxanthine, adenine, xanthine and guanine) and compete with their cellular functions.  Example of those chemotherapeutic agents are mercaptopurine {leukerine (9)} and azathiopurine{ Imuran (10) }they are proved to inhibit aminotransferase, adenylsuccinate synthase, adenylsuccinate lyase and inosine monophosphate dehydrogenase enzymatic systems leading to protein synthesis inhibition followed by cell death.

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55  Normal cell can get its need from these bases through: A.De Novo Purine Synthesis B.Salvage Purine Synthesis A. De Novo Purine Synthesis

56 B.Salvage Purine Synthesis

57 6-Mercaptopurine or purine-6-thiol. Synthesis

58 Mechanism of Action 1.Inhibition of De Novo Synthesis

59 2.Inhibition of Salvage Purine Synthesis

60 2-Amino-6-mercaptopurine

61 6-[(1-Methyl-4-nitroimidazol-5- yl)thio]purine Synthesis

62 2-Amino-6-hydroxy-8- azapurine

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64  Fluorouracil (11) and cytarabine (12) represent this group of compounds.  They resemble the natural pyrimidine (uracil, thymine and cytosine) in structures and compete with their cellular functions leading to the inhibition of two vital enzymatic systems responsible for the production of thymine from uracil.  These two enzymes are ribonucleotide reductase and thymidylate synthase.

65 Ribose-1-P Uridine phosphorylase ATP ADP Uridine kinase ATP ADP UMP kinase Ribonucleotide reductase The metabolic role of ribonucleotide reductase enzyme

66  Normal cells can get its need from these bases through: 1.De Novo Pyrimidine Synthesis

67 2.Salvage Pyrimidine Synthesis

68 5-Fluorouracil or 5-Fluoro-2,4 (1H, 3H)- pyrimidindione. Mode of action (1)

69 5-Fluorouracil or 5-Fluoro-2,4 (1H, 3H)- pyrimidindione. Mode of action (2)

70 4-Amino-1-B-D-arabinofuranosyl-2(1H)- pyrimidinone. Synthesis

71 Mode of Action

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73  Folic acid metabolism is an important source for one carbon moiety needed to convert uracil into thymine.  Inhibition of folic acid metabolism, in other words, inhibition of dihydrofolate reductase will deplete the cellular systems from thymine – a pyrimidine base-very much needed for nucleic acid biosynthesis.  Methotrexate (13) and fluorouracil (11) represent this class of compounds.

74 Dihydrofolate reductase Thymidylate synthetase Uracil Thymine H 2 NCH 2 CO 2 H Metabolic role of dihydrofolate reductase

75  Based on that, folic acid antagonists could be classified into: A. Dirhydrofolate reductase inhibitors  Methotrexate, Mexate, Amethopterin B. Thymidylate synthetase inhibitors  Fluorouracil, Fluoroplex:

76  Methotrexate, Mexate, Amethopterin: 4-Amino-10-methylpteroylglutamic acid

77  Methotrexate, Mexate, Amethopterin:  Synthesis I 2,KI, Ca(OH) 2 ++

78  Methotrexate, Mexate, Amethopterin:  Mode of Action  Dihydrofolate reductase utilizes methotrexate to produce a tetrahydrofolate derivative which then accumulates leading to enzyme inhibition.  Accumulation of tetrahydromethotrexate will inhibit tetrahydrofolate reductase enzyme.  This will lead to depletion of thymine stores   DNA & RNA synthesis.

79  Methotrexate, Mexate, Amethopterin:

80  Contraindications:  Salicylates and sulfonamides increase methotrexate toxicity by:  1. inhibiting its renal tubular secretion.  2. they displace methotrexate from plasma protein binding.

81  Fluorouracil, Fluoroplex 5-Fluoro-2,4-(1H, 3H)-pyrimidindione  Mode of Action It interacts irreversibly with tetrahydrofolate making it unavailable for thymidine synthetase leading to the inhibition of thymidine production.

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83  Some cancers are responsive to sex hormone treatment.  Hormones control the dissemination of cancer but suffer from side effects as:  1.Androgens  musculinizing effect  2.Estrogens  feminizing effect  3.Adrenocorticoids  salt and water retention  Tamoxifen citrate is a nonsteroidal drug with anti-estrogenic effect used as anticancer

84  Mode of Action  Tamoxifen is an estrogen receptor antagonist, blocks the growth promoting effects of estrogen in tumors.  Uses:Advanced breast carcinoma. 2-[4-(1,2-Diphenyl-1-butenyl)phenoxy]-N,N-dimethylethanamine citrate.

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