Chemotherapy Flashcards
Define primary chemotherapy?
Chemotherapy indicated when neoplasms are disseminated and not amenable to surgery
Define adjuvant chemotherapy?
Chemotherapy used to attack micrometastases following surgery and radiation
Define neoadjuvant chemotherapy?
Chemotherapy given prior to surgery to shrink the cancer
Methotrexate
MOA: inhibits dihydrofolate reductase > decrease synthesis of dTMP and purine nucleotides > decrease DNA, RNA, protein synthesis > cell death
AE: common is stomatits, myelosuppression, alopecia, nausea, and vomiting. Others are renal damage, hepatic fibrosis/cirrhosis, pneumonitis, and neurological toxicites
HL: metabolized by folylpolyglutamate synthase (FPGS) to polygulamates (MTX-PGs). Given in combination with Leucovorin which is N5-formyl-THF which provides normal tissue with reduced folate
What are the two purine analogs?
6-mercaptopurine and 6-thioguanine
6-mercaptopurine
MOA: convereted to thio-IMP by HGPRT > inhibits first step of de novo purine ring biosynthesis and blocks formation of AMP/GMP from IMP > dysfunctional RNA and DNA > cell death
AE: nausea, vomiting, diarrhea, bone marrow supression, and hepatotoxicity
HL: metabolized by xanathine oxidase to thiouric acid and by thiopuring methyltransferase (TPMT). If allopurinol is given with reduce hyperuricemia dose of 6-MP must be reduced because allopurinol is xanthine oxidase inhibitor.
6-thioguanine
MOA: converted to nucleotide > inhibits purine synthesis and the phosphorylation of GMP to GDP
AE: nausea, vomiting, diarrhea, bone marrow suppression, hepatotoxicity
HL: allopurinol does not potentiate 6-TG action because very little is metabolized to thiouric acid. Metabolized by thiopuring methyltransferase (TPMT)
What are the 3 pyrimidine analogs?
5-fluorouracil, Capecitabine, and Cytarabine
5-fluorouracil
MOA: converted to 5-FdUMP and 5-FUTP > inhibits thymidylate synthase > thymineless death
AE: nause vomiting, alopecia, bone marrow depression and hand-foot syndrome
HL: combined with leucovorin for colorectal cancer because increasing levels of N5,N10-methylene-THF potentiates activity
Capecitabine
MOA: same as 5-FU
AE: same as 5-FU
HL:
Cytarabine (ARA-C)
MOA: analog of deoxycytidine > phosphorylated to triphosphate > incorporated into DNA > inhibits DNA polymerase
AE:
HL:
Anthracyclines (Doxorubicin and Daunorubicin)
MOA: inhibition of topoisomerase II, intercalation in DNA with consequent blockade of DNA/RNA synthesis and strand breakage, binding to cell membranes to alter fluidity/ion transport, generation of free radicals
AE: myelosuppression, cardiotoxicity
HL: dexrazoxane can redue the cardiotoxicity
Bleomycin
MOA: mixture of glycopeptides > DNA-bleomycin-Fe2+ > oxidation to bleomycin-Fe3+ > reacts with O2 forming free radicals > strand breakdown
AE: very little myelosuppression, pulmonary toxicity (pneumonitis, fibrosis)
HL: cell-cycle specific with arrest cells in G2 phase
What are the different types of alkylating agents?
Nitrogen mustards, nitrosoureas, other alkylating agents, and platinum coordination complexes
What are the 3 nitrogen mustards?
Mechlorethamine, cyclophasphamide, and melphalan
Mechlorethamine
MOA: alkyating > cell death
AE: severe nausea/vomiting, severe bone marrow depression, alopecia, immunosuppression,
HL: powerful vesicant so only given by IV
Cyclophosphamide
MOA: alkylating > cell death
AE: nasuea/vomiting, bone marrow depression, hemorrhagic cystitis, alopecia, and sterility
HL: its a prodrug, most widely used, and mesna + fluid intake is taken to prevent acrolein buildup leading to hemorrhagic cystitis
Melphalan
MOA: alkylating agent > cell death
AE: bone marrow suppression