Anticancer I Flashcards Preview

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Flashcards in Anticancer I Deck (57):
1

What are the 7 classes of anticancer agents?

Alkylating agents
Antimetabolite and nucleoside analogs
Antitumor antibiotics
Antimitotic agents
Miscellaneous antineoplastics
Hormonal therapy
Combination therapy

2

What are the different alkylating agents?

Nitrogen mustards
Phosphoamide mustards
Nitrosoureas
Platins
Other alkylating agents

3

What is the main MOA of alkylating agents?

React with DNA, preferentially alkylating the N-7 position of guanine (most common)
Bifunctional alkylating agents product inter- or intra-strand crosslinks preventing DNA separation

4

What is the MOA of nitrogen mustards?

They activate the chloride

5

What are some nitrogen mustards?

Melphalan
Cyclophosphamide
Ifosfamide
Chlorambucil
Estramustine phosphate

6

What are some other alkylating anticancer agents?

Busulfan (Myleran)
Thiopeta
Procarbazine (Matulane)
Dacarbazine

7

What is the MOA of nitrosureas?

Urea NH is deprotonated and the negatively charged oxygen displaces chloride to give a cyclic oxazolidine, which fragments to give 2-chloroethylisocyanate and vinyl diazohydroxide, which decomposes to give electrophilic vinyl cation

8

What are some nitrosureas?

Carmustine (BiCNU)
Lomustine (CeeNU)
Streptozin (Zanosar)

9

What are some platins?

Cisplatin
Carboplatin

10

What is the MOA of antimetabolites?

They care closely related to cellular precursors and thus they prevent use or formation of normal cellular products.

11

What are the MOAs of pyrimidine-based antimetabolites?

Inhibition of kinases
Inhibition of enzymes involved in pyrimidine biosynthesis
Incorporation into RNA or DNA, causes misreading
Inhibition of DNA polymerase

12

What is the role of folate?

DNA synthesis
DNA repair
DNA methylation
Cofactor

13

What are the active forms of folate?

Tetrahydrofolate and dihydrofolate

14

What do dihydrofolate reductase (DHFR) inhibitors do?

They inhibit DHFR, which leads to:
Decreased levels of FH2 and FH4
Decreased conversion of dUMP into dTMP
Decreased DNA synthesis

15

What are some DHFR inhibitors?

Methotrexate
Pemetrexed (Alimta)
Pralatrexate (Folotyn)

16

What does pralatrexate do?

Inhibits enzymes used in purine and pyrimidine synthesis:
thymidylate synthase
dihydrofolate reductase
glycinamide ribonucleotide formyltransferase

17

What does folinic acid do?

Adjuvant used in cancer chemotherapy to "rescue" bone marrow and GI mucosa cells from methotrexate

18

What is 5-fluorouracil?

"Mechanism-based" prodrug that acts as a suicide substrate and directly inhibits the thymidylate synthase

19

What are the 3 main active metabolites of 5-fluorouracil?

Fluorodeoxyuridine monophosphate (FdUMP)
Fluorodeoxyuridine triphosphate (FdUTP)
Fluorouridine triphosphate (FUTP)

20

What is the MOA of 5-FU (specifically, it's active metabolite FdUMP)?

Direct inhibition of TS via the formation of a ternary complex in the nucleotide-binding site. This blocks dUMP from accessing the binding site.
This leads to an increase in dUTP, which causes DNA damage

21

What are some other pyrimidine-based antimetabolites?

Cytarabine (ARA-C)
Gemcitabine

22

What are some purine-based antimetabolites?

6-mercaptopurine
6-thioguanine
Fludarabbine phoshpate (Fludara)
Cladribine

23

What is the MOA of 6-mercaptopurine?

Blocks the synthesis of PRA and PRPP

24

What are some antitumor antibiotics?

Bleomycins
Anthracyclines
Etoposide and teniposide
Camptothecins
Actinomycins
Mitomycins

25

What are bleomycins?

Cytotoxic glycopeptides

26

What is the MOA of bleomycins?

Chelates metail ions (Fe, Cu) producing a pseudo enzyme that reacts with oxygen to produce free radicals, causing DNA strand breaks

27

What is required for bleomycin DNA strand breaking? How is this achieved?

Reactivation and reorganization of bleomycin
The key to reorganization is the linker and the flexibility of the bithiazole tail

28

What are some topoisomerase poisons?

Amsacrine
Etoposide
Doxorubicin
Mitoxantrone

29

What are the functions of DNA topoisomerase?

DNA replication
DNA recombination
Chromosome condensation/decondensation
Segregation of sister chromatids

30

What do topoisomerase II poisons do?

Cause single and double strand DNA breaks
Increase in topoisomerase II levels - renders cell hypersensitive (more enzyme, more DNA breaks)
Stabilize topoisomerase II-DNA covalent complexes

31

What does topoisomerase II catalytic inhibitors do (...not do)?

Do not cause DNA strand breaks
Do not stabilize topoisomerase II-DNA cleavable complexes (and may destabilize them)

32

What is the MOA of anthracyclines?

intercalation followed by inhibition of topoisomerase II leading to DNA strand breakage and apoptosis
Additional mechanism: generation of free radicals

33

What are the 5 clinically useful anthracyclines?

Doxorubicin
Daunorubicin
Epirubicin
Idarubicin
Valrubicin

34

What limits the use of doxorubicin?

Cardiotoxicity; doxorubicin is a quinone and can be reduced to a semiquinone. The semiquinone reacts with oxygen to reform the quinone (redox cycling)
Doxorubicin also forms a strong complex with Fe3+, which can be reduced to Fe2+, which can form free radicals

35

What limits the use of etoposide?

Myelosuppression

36

What is the MOA of camptothecins?

Inhibitor of topoisomerase I (prevents realignment and resealing); leads to double stranded DNA breaks and cell death

37

What is increases the water solubility of campothecins to create topotecan and Irinotecan?

Addition of basic amine side chains

38

What's the difference between topoisomerase I and II?

Top. I: single strand break
Top. II: double strand break

39

What are some antimitotic compounds?

Vinca alkaloids
Taxanes
Epothilones
IXA

40

What are the two conjoined groups of vinca alkaloids?

Catharanthine moiety (indole, azonine, piperidine ring systms)
Vindoline moiety (dihydroindole, cyclohexane, pyrrolidine, piperidine)

41

What is the MOA of vinca alkaloids?

Disrupt formation of mitotic spindles, inhibiting microtubule assembly

42

What are some vinca alkaloids?

Vinblastine
Vincristine
Vinorelbine

43

What is the MOA of taxenes?

They bind to tubular at a different site than vinca alkaloids
This stabilizes microtubules and prevent depolymerization, blocking mitosis

44

What are some taxanes?

Paclitaxel (Taxol)
Docetaxel (Taxotere)

45

What does vinblastine bind to the microtubule? What does paclitaxel bind?

Vinblastine binds to the plus end
Paclitexel binds on the interior surface

46

What are epothilones?

They are macrocyclic lactones that have a MOA similar to taxanes but offer several advantages (don't require Cremophor EL for water solubility)

47

What is IXA used for?

Taxane-resistant breast cancer

48

What growth factors do we often target with several drugs and monoclonal antibodies to control overgrowth of cells/tissues?

Epidermal GF
Platelet-derived GF
Nerve GF
Vascular endothelial GF
Stem cell F

49

What is the MOA of protein tyrosine kinase inhibitors

Kinase inhibitors mimic ATP to inhibit tyrosine kinases

50

What is the first protein tyrosine kinase inhibitor on the market?

Imatinib (Gleevec) for chronic myelogenous leukemia

51

What are other protein tyrosine kinase inhibitors?

Nilotinib
Dasatinib
Bosutinib
Ponatinib

52

How do type I kinase inhibitors bind?

They bind to the active conformation of the kinase with the aspartate residue and the DFG motif pointing into the ATP-binding pocket

53

How do the type II kinase inhibitors bind?

They bind and stabilize the inactive conformation of the kinase with the flipped aspartate residue facing outward of the binding pocket

54

What are the limitations of kinase inhibitors?

Cardiotoxicity (CHF, decreased ejection fraction, ischemia, infarction)

55

What are some anticancer monoclonal antibodies?

Bevacizumab
Cetuximab
Ipilimumab
Nivolumab
Ofatumumab
Paitumumab
Rituximab

56

What is the MOA of Bortezomib?

Inhibits proteosomes

57

What is the MOA of dactinomycin?

Binds to DNA by intercalation, inhibiting DNA function