Antineoplastic agents II Flashcards
What are the three major ways in which tumors become resistant to cytarabine?
- Downregulate transporter
- Downregulate deoxycyidine
- Upregulate cytidine deaminase
What is the MOA of gemcitabine?
difluorodeoxycytidine is converted by deoxycitidine kinase, and is incoroprated into DNA, and inhibits ribonucleotide reductase
What are the two MOA of resistance to gemcitabine?
Reduced deoxycytidine kinase
Increased production of deoxycytidine
What is the MOA of 6-mercaptopurine and 6-thioguanine?
HGPRT enzyme converts them to thio IMP or thioGMP, inhibiting RNA/DNA synthesis
What is the enzyme that degrades 6MP and 6TG? What is significant about this enzyme?
Thiopurine methyltransferase (TPMT)
Some in the population do not have this, thus have much higher toxicity levels
What are the cancers that 6MP and 6TP treat?
Acute myelogenous leukemia
Acute lymphocytic leukemia
What are the adverse effects of 6MP and 6TP?
Bone marrow suppression
What is the MOA of resistance to 6MP and 6TP?
Deficiency in HGPRT
What is the MOA of fludarabine?
Deoxycitidine kinase activates it in cells, and it is incorporated into DNA/RNA, and inhibiting DNA polymerase and ribonucleotide reductase
What are the cancers the fludarabine is used to treat?
chronic lymphocytic leukemia
What is the MOA of resistance to fludarabine and cladribine?
Decreased deoxycitidine kinase
What is the MOA of cladribine?
Deoxycitidine kinase activates it in cells, and it is incorporated into DNA/RNA, and inhibiting DNA polymerase and ribonucleotide reductase
What is the enzyme that activates fludarabine and cladribine?
deoxycitidine kinase
Why do we have to give purine/pyrimidine analogs in an inactive form?
Otherwise will not enter the cell
What is the cancer that cladribine?
Hair cell leukemia
What is the general MOA of alkylating agents?
intrastrand linking and cross linking
When in the cell cycle are alkylating agents effective?
All stages
What are the two nitrogen mustards that are used as alkylating agents?
Mechlorethamine
Cyclophosphamide
What cancer is mechlorethamine used to treat?
Hodgkin’s lymphoma
What are the unique adverse effects of cyclophosphamide? MOA?
Hemorrhagic cystitis
converted to acrolein, which is toxic to the baldder cells
What is the drug that you coadminister with cyclophosphamide to reduce the chances of developing hemorrhagic cystitis? MOA?
Mesna
Inactivates acrolein
What is the MOA of carmustine?
Alkylating agent
What is carmustine used to treat?
Brain ca
What are the adverse effects of alkylating agents?
Mutagenic, teratogenic, and myelosuppressive
What cancer develops with the use of alkylating agents?
Leukemia
Besides the usual routes of resistance to drugs, how do tumor resist alkylating agents?
Inactivation by glutathione
Increased expression of 06-methylguanine-DNA methyltransferase (MGMT)
What is the MOA of 06-methylguanine-DNA methyltransferase (MGMT)?
Removes the alkyl groups on DNA that were added by alkylating agents
What is the MOA of the platinum compunds?
Cause cross-linking of DNA
What are the three platinum compounds that act like alkylating agents?
Cisplatin
Carboplatin
Oxaliplatin
Platinum compounds increase the risk for what cancer?
Leukemia
Which causes less n/v: cisplatin or carboplatin?
Carboplatin
What are the adverse effects of cisplatin?
tinnitus
Nephrotoxicity
peripheral neuropathy
What is the MOA of procarbazine? What is it used to treat?
board
Non-classical alkylating agent
Hodgkins
What is the MOA of dacarbazine?
board
Non-classical alkylating agent
melanoima/sarcoma
What is the MOA of temozolomide?
board
Non-classical alkylating agent
Glioblastomas
What is the dynamic instability of microtubules?
Constant breakdown and restructuring
What is the MOA of vinblasine and vincristine?
Causes mitotic arrest by preventing formation of microtubules
Which drug has neurotoxicity: vinblastine or vincristine?
Vincristine
What is the MOA of paclitaxel?
Binds to beta tubulin of microtubules, and prevent the disassembly
What is the MOA of docetaxel?
Binds to beta tubulin of microtubules, and prevent the disassembly
What are the adverse effects of paclitaxel?
Myelosuppression and peripheral neuropathy
What are the adverse effects of docetaxel?
Periperhal neuropathy
What is the drug that is used with paclitaxel, to reduce myelosuppression?
Filgrastim
What do topoisomerases do in DNA replication?
Cut DNA, unwind, and repair the cut
What are the two topoisomerase inhibitors?
Irinotecan
Topotecan
What is the MOA of etoposide?
Class IITopoisomerase inhibitor
What is the MOA of doxorubin?
Abx that intercalates with DNA, leading to inhibition of DNA polymerase
What is the significant adverse effect of doxorubin?
cardiomyopathy via free radical formation
What is the drug that is administered with doxorubicin that mitigates the cardiotoxicity?
Dexrazoxane (Fe chelator)
What is the MOA of bleomycin?
Small glycopeptide antibiotic that chelates iron and copper and binds to DNA and causes
single and double strand breaks.
What are the adverse effects of bleomycin?
Pulmonary toxicity
Which of the antineoplastic are minimally myelosuppressive (3)?
Bleomycin
Vincritine
Methotrexate
What is the MOA of glucocorticoids in the treatment of cancer?
Inhibit lymphocyte proliferation
What is the MOA of dexamethasone?
Glucocorticoid
What is the MOA of tamoxifen?
Selective estrogen receptor modulator (competes for estrogen receptor)
What are the adverse effects of tamoxifen?
Increased risk of endometrial CA
Increased risk of thromboembolism
What are the resistance mechanisms of tamoxifen?
Estrogen receptor changes cause a reduced affinity with tamoxifen.
What is the MOA of anastrozole?
Aromatase inhibitor (recall that aromatase synthesizes estrogen from androgens in peripheral tissue)
What is anastrozole used for?
Treatment of breast cancers
What are the two androgen receptor inhibitors? What are thy used to treat?
Flutamide
Bicalutamide
Prostate CA
What is the MOA of flutamide?
androgen receptor inhibitor
What is the MOA of bicalutamide?
androgen receptor inhibitor
What is the MOA of leuprolide?
GnRH agonist
What is the MOA of goserelin?
GnRH agonist
How do the GnRH agonists work?
Cause a desensitization of the GnRH receptors, which reduces the secretion of both LH
and FSH from the anterior pituitary
What is the MOA of degarelix
GnRH antagonist, which decreases LH and FSH production
What is the MOA of trastuzumab?
Binds to estrogen growth signal receptor (HER2), and inhibits it
What is the MOA of cetuximab?
Monoclonal antibody against EGFR
What are the adverse effects of trastuzumab?
Cardiac toxicity if combined
What cancer does cetuximab treat?
EGRF expressing Colorectal cancers
What is the mechanism of resistance to cetuximab?
Acquiring activating mutations in RAS
What is the general MOA of monoclonal antibodies in treating CA?
Inhibit growth signals
Cause immune mediated destruction
What is the MOA of bevacizumab?
Ab against VEGF, inhibiting angiogenesis
What is the cancer that bevacizumab is used to treat?
clear cell renal cancer
What are the adverse effects of bevacizumab?
significant blood vessel injury and reduces wound healing
What is the MOA of lapatinib?
Inhibits EGFR and HER-2 kinase activity
What is the MOA of erlotinib?
EGRF inhibitor
ATP competitive inhibitor
How does the EGRF molecule work?
Y kinase that is activated extracellularly, when epidermal growth factor binds, and activates the MAP kinase cascade
What is the therapeutic use of erlotinib?
Nonsmall cell lung carcinoma if pts have mutation in gene
How does resistance come about with erlotinib?
Secondary mutation in EGRF or amplification of MET oncogene
What is the MOA of imantinib (gleevec)?
Binds to ABL portion of the philidelphia chromosome, and prevents kinase from binding its substrate/phosphate donor
What is imantinib used to treat?
Chronic myelogenous leukemia
What is the mechanism of resistance to imantinib?
Point mutation BCR-ABL protein to not bind imantinib anymore
What is the MOA of asparaginase?
Lowers blood [asparagine], which kills tumor cells since they cannot synthesize sufficient asparagine
What is asparaginase used to treat?
acute lymphoblastic leukemia
What are the adverse effects of aparaginase?
anaphylaxis
What is the MOA of bortezomib? (2)
Inhibits proteasome, which increases p53
What cancer does bortezomib treat?
multiple myeloma
What is the main adverse effect with bortezomib?
Peripheral neuropathy
What is the MOA of temsirolimus?
inhibition of mTOR complex, which promotes cell cycle
What cancer is temsirolimus used to treat?
renal cell carcinoma
What is the mechanism of resistance against temsirolimus?
mTOR 2 increased