Antineoplastic agents II Flashcards
what class of antimetabolite are 6-TG and 6-MP? what is the mechanism of action?
- purine analog
- inhibit purine synthesis - reduces RNA and DNA precursors
- incorporate into DNA
which enzyme activates 6-TG and 6-MP? what are the activation products?
- hypoxanthine guanine phosphoribyl transferase (HGPRT)
2. thio-IMP and thio-GMP
what is the mechanism of resistance for 6-TG and 6-MP?
decreased activity of HGPRT
which enzyme inactivates 6-TG and 6-MP?
thiopurine methyltransferase (TPMT)
what class of antimetabolite is fludarabine? what is the mechanism of action?
- purine analog
- incorporated into DNA and RNA
- inhibits DNA polymerase and ribonucleotide reductase
which enzyme is necessary to activate fludarabine?
deoxycytidine kinase
what class of antimetabolite is cladribine? what is the mechanism of action?
- purine analog
- incorporated into DNA
- causes strand breaks
- inhibits ribonucleotide reductase (lowers precursor pool)
which type of cancer is cladribine commonly used for?
hairy cell leukemia
which enzyme is necessary to activate cladribine?
deoxycytidine kinase
what is the most nucleophilic group in the DNA backbone?
7-nitrogen group on guanine
what class of drug is cyclophosphamide? what is the MOA?
- classical alkylating agent
2. causes DNA cross linking and strand breakage
what is an important side effect of cyclophosphamide? why?
- hemorrhagic cystitis
2. active form can convert to acrolein (toxic to bladder cells)
coadministration of which drug can inactivate acrolein and mitigate the side effects of cyclophosphamide?
mesna
why is carmustine a good agent for brain tumors?
very lipophilic - can cross BBB
what class of drug is carmustine? what is the MOA?
- classical alkylating agent
2. causes DNA cross linking and strand breakage
what are the general adverse effects of alkylating agents?
- mutagenic
- teratogenic
- myelosuppressive
what are the mechanisms of resistance for alkylating agents?
- inactivation by glutathione
- reduced uptake
- accelerated DNA repair
- increased expression of MGMT (removes alkyl groups from guanine before cross links occur)
what are the non-classical alkylating agents?
- cisplatin
- carboplatin
- oxaliplatin
what is the MOA of the non-classical alkylating agents?
target nucleophilic center (guanine N7)
what are the differences in side effects between cisplatin and carboplatin?
- carboplatin - less nausea (dose limiting toxicity is myelosuppression)
- cisplatin - peripheral neuropathy and neurotoxicity
what class of drug are vinblastine and vincristine? what is the MOA?
- antimicrotubule
2. inhibit polymerization of tubulin (microtubules) - improper segregation of chromosomes in mitosis
what are the adverse effects of vincristine?
mostly neurological - numbness, tingling in extremities, motor weakness
what are the adverse effects of vinblastine?
mostly myelosuppression
what class of drug is paclitaxel? what is the MOA?
- antimicrotubule
2. prevents depolymerization of microtubules - arrests cells in mitosis
what are the main adverse effects of paclitaxel?
- peripheral neuropathy
2. hypersensitivity
paclitaxel is used with which drug to reduce myelosuppression?
filgrastim (GCSF)
what are the topoisomerase I inhibitors?
- irinotecan
2. topotecan
what is the topoisomerase II inhibitor?
etoposide
what class of drug is doxorubicin? what is the MOA?
- antracycyline antibiotic
- intercalates with DNA, inhibits DNA polymerase
- inhibits topoisomerase II
- binds iron and generates free radicals - kills by DNA and protein damage
what is the important adverse effect of doxorubicin? why?
- irreversible cardiomyopathy
2. iron-generated free radical damage
coadministration of which drug mitigates the toxicity of doxorubicin?
dexrazoxane (iron chelator)
what is the MOA of bleomycin?
binds to DNA - causes single and double strand breaks
what is an advantage of bleomycin?
minimally myelosuppressive and immunosuppressive
what is the dose limiting toxicity of bleomycin?
pulmonary toxicity
bleomycin causes cells to arrest in which phase?
G2
the majority of cytotoxic agents induce what major adverse effect?
myelosuppression
what is the MOA of tamoxifen?
- competitively binds estrogen receptor
2. reduces growth of estrogen dependent breast cancers
what class of drug is anastrazole? what is the MOA?
- aromatase inhibitor (inhibits conversion of testosterone to estrogen)
- lowers estrogen levels in post-menopausal women
what class of drug is flutamide? what is the MOA?
- androgen receptor antagonist
2. prevent dihydrotestosterone from binding to androgen receptors - for prostate cancer
what class of drug is leuprolide? what is the MOA?
- GnRH agonist
2. desensitizes gonadotropin receptors over the long run, decreases LH and FSH levels and thus testosterone levels
what class of drug is trastuzamab (herceptin)? what is the MOA?
- inhibitor of kinase signal transduction
2. monoclonal Ab that binds HER-2 receptor - prevents it from signaling
what class of drug is cetuximab? what is the MOA?
- inhibitor of kinase signal transduction
2. monoclonal Ab that binds EGFR receptor - prevents it from signaling
what is the drug of choice for breast cancers with amplified HER-2?
trastuximab (herceptin)
what is the main toxicity for trastuximab (herceptin)?
cardiotoxic
cetuximab is used for what types of tumors?
colorectal
activation of what protein precludes the use of cetuximab?
Ras
bevacizumab is a monoclonal antibody directed against what growth factor?
VEGF
what is the MOA of lapatinib?
inhibits both EGFR and HER-2 kinase activity
what drug can be used to treat breast cancers that are HER-2 amplified but resistant to trastuzamab?
lapatinib
what is the MOA of erlotinib?
- EGFR inhibitor
2. ATP competitive inhibitor
what type of cancer is imatinib used for? what is the MOA?
- CML
2. inhibits BCR-ABL fusion protein from Philadelphia chromosome - inhibits tyrosine kinase activity
what type of cancer is asparaginase used for? what is the MOA?
- ALL
- causes degradation of L-asparagine to L-aspartate
- selective starvation of asparagine
- occurs in serum
what is a unique adverse effect specific to asparaginase?
hypersensitivity
bortezomib is what class of drug? what is the MOA?
- proteasome inhibitor
2. elevates p53 levels
what is the unique adverse effect of bortezomib?
peripheral neuropathy
temsirolimus is used to treat what type of cancer? what is the MOA?
- renal cell carcinoma
2. inhibits mTOR - reduces protein translation, inhibits cell cycle, promotes apoptosis