Cancer Pharm (Liz P.) Flashcards
Major MOA of alkylating agents and causes arrest where in cell cycle?
- Transfer of alkyl group to DNA –> DNA cross-linking
- Arrest occurs in late G1, early S phase
What are 3 mechanisms to resistance of Alkylating agents?
- ↑ capability to repair DNA lesion –> ↑ expression MGMT
- ↓ cellular transport of the alkylating drug
- ↑ expression of glutathione
What is the most widely used alkylating agent that has a high oral bioavailability and can be given IV?
Cyclophosphamide
Which toxic metabolite of Cyclophosphamide is responsible for the antitumor effects?
Phosphoramide mustard
Which toxic metabolite of Cyclophosphamide is associated with hemorrhagic cystitis?
Acrolein
What should patients receive when on high doses of Cyclophosphamide?
Vigorous IV hydration
Complete remissions and presumed cures have been seen with Cyclophosphamide when given as a single agent for what type of cancer?
Burkitt Lymphoma
Which 2 alkylating agents are lipid soluble nitrosoureas allowing them to cross BBB and be effective in treating brain tumors?
Carmustine and Streptozocin
- Generate both alkylating and carbamylating moieties
What is the clinical use of Carmustine and what makes this drug so effective in these tumors?
- Malignant Glimoas (implantable Carmustine wafer)
- Methylation of the MGMT promter inhibits MGMT expression in 30% of primary gliomas
- Assoc. w/ sensitivity to carmustine and other nitrosureas
What are the AE’s associated with the alkylsulfonate, Busulfan, at high doses?
ulmonary fibrosis** + GI mucosal damage + hepatic VOD
What alkylatingn agen can be used to treat malignant melanoma?
Dacarbazing and Cisplatin however the response to them is low
What is the MOA of Methotrexate?
- Inhibits synthesis of THF
- Interferes w/ formation of DNA, RNA, and key cellular proteins
What are 4 mechanisms by which resistance to Methotrexate may develop?↓
- ↓ drug transport via the reduced folate carrier or folate receptor protein
- ↓ formation of cytotoxic methotrexate polyglutamines
- ↑ levels of the target enzyme DHFR thru gene amplification, etc.
- Altered DHFR protein with reduced affinity for methotrexate
What are 4 drug-drug interactions that you must be aware of when giving Methotrexate?
Aspirin, NSAIDs, penicillin, and cephalosporins all inhibit its renal excretion —> ↑ toxicity
Aspirin, NSAIDs, penicillin, and cephalosporins all inhibit its renal excretion —> ↑ toxicity
Aspirin, NSAIDs, penicillin, and cephalosporins all inhibit its renal excretion —> ↑ toxicity
What are the 3 active metabolites of 5-FU and what is the MOA of each?
- FdUMP —> inhibition of DNA synthesis thru “thymineless death”
- FUTP –> incorporated in RNA; interferes w/ RNA processing and mRNA translation
- FdUTP –> incorporated into DNA resulting in inhibition of DNA synthesis
What are 4 AE’s of the antimetabolite, 5-FU; which is unique?
- GI toxicity (diarrhea/mucositis) = unique
- Myelosuppression
- Skin toxicity (hand-foot syndrome) = unique
- Neurotoxicity
5-FU is the most widely used drug in the tx of which cancer?
Colorectal cancer
6-mercaptopurine (6-MP) is inactive in parent form and becomes active when metabolized to what?
Metabolized by HGPRT –> monophosphate nucleotide 6-thioinosinic acid
What is the MOA of the active metabolite of 6-MP, mono- and triphosphate nucleotide 6-thioinosinic acid?
Monophosphate acts to inhibit several enzymes of de novo purine nucleotide synthesis
- Triphosphate form incorporated into both DNA and RNA
How is the active form of 6-mercaptopurine (6-MP) inactivated and what clinical implication does this have?
- Converted to inactive metabolite by xanthine oxidase
- Allopurinol (xanthine oxidase inhibitor) is commonly used in tx of acute leukemia for prevention of hyperuricemia
- If allopurinol is used w/ 6-MP, would result in ↑ levels of 6-MP and excessive toxicity
6-mercaptopurine is used in the tx of what?
Childhood acute leukemia
List the 5 MOA of 6-thioguanine?
- Inhibits several enzymes in de novo purine nucleotide synthesis