Cancer Chemotherapy 1&2 - Duan Flashcards
Name some characteristics of cancer cells.
- cancer is a disease of our own cells
- they exhibit shorter or accelerated cell cycles
- cancer cells undergo excessive proliferation
- exhibit higher activity of nucleic acid and protein synthesis
- exhibits altered cell-cell communication
- cancer cells are invasive and disrupt normal healthy tissues
- exhibit migration to distant sites - metastasis
Do cancer cell use the same nutrients and metabolic process abnormal host cell?
Yes
What stage of the cell cycle are most cells found in?
The G0 or resting phase.
Name, in order, the phases of the cell cycle.
- G0 - resting phase
- G1 - pre-synthesis or first gap phase
- S phase - DNA synthesis
- G2 - pre-mitotic interval or second gap phase
- M phase - mitosis
- back to G1 or G0
What phases of the cell cycle contain restriction points?
- G1
2. G2
What anti-cancer drug target the G1 phase of the cell cycle?
Mitomycin C
What anti-cancer drugs target the S phase of the cell cycle?
- Cytosine arabinoside
- Hydroxyurea
- 6-MP
- MTX
- 5-FU
What anti-cancer drug targets the G2 phase of the cell cycle?
Etoposide
Which anti-cancer drugs target the M phase of the cell cycle?
- Vincristine
- Vinblastine
- Taxanes
Name the general classes of anticancer drugs.
- Alkylating agents
- Antimetabolites
- Antibiotics
- Natural products
- Miscellaneous
- Hormones
What anti-cancer drugs are alkylating agents?
- Nitrogen mustards - Mechlorthamine, Cyclophosphamide, Ifosfamide
- Nitrosoureas - Carmustine, Streptozotocin, Lomustine
- Alkyl sulfonates - Busulfan
What anti-cancer drugs are antimetabolites?
- Folate antagonists - Methotrexate
- Purine antagonists - 6-Mercaptopurine
- Pyrimadine antagonists - 5- Fluorouracil
What anti- cancer drugs are antibiotics?
- Doxorubicin - also called Adriamycin
- Bleomycin - also called Bienoxane
- Mitomycin
What anti- cancer drugs are in the miscellaneous category?
- Platinum compounds - Cisplatin, Carboplatin
- Procarbazine
- L- Asparaginase
- Imatinib
What anti-cancer drugs are natural products?
- Vinca alkaloids
Etoposide
What anti-cancer drugs are hormones?
- Glucocorticoids
2. Tamoxifen
What is the mechanism of action of the alkylating agent class of drugs?
They impair cell function by forming covalent bonds with the amino, carboxyl, sulfhydryl and phosphate groups in biologically important molecules. This causes non-specific cross linking of DNA. The cell is damaged and will die during its next cell division.
Which position in DNA is particularly susceptible to alkylation?
The electron rich nitrogen at the N7 position of guanine.
Are alkylating agents cell cycle specific drugs?
No, they are active even for resting cells in G0.
Describe some characteristics of the nitrogen mustards.
- an alkylating agent
- main toxicity comes from DNA cross linkage
- the chloroethyl side chains of the nitrogen mustard molecule undergoes intramolcular cyclization and forms a carbonium ion intermediate
- the carbonium ion is a strong electrophile
- the electron donor (N7 of guanine residue in DNA or the SH of protein) undergoes nucleophilic attack by the carbonium ion and a complex is formed
What are the effects of alkylation of N7 of guanine residues in DNA?
- the guanine can mispair with a thymine residue during DNA synthesis - this leads to the substitution of an AT pair for the GC pair
- the guanine residue is excised and this leads to the opening of the imidazole ring of guanine
- with bifunctional alkylating agents another guanine residue is alkylated and cross linking of the two chains (or 2 spots on the same chain) results - or the link could be between a nucleic acid and a protein
What are the nitrogen mustard drugs used for?
They are used in combination with other drugs to treat lymphomas and leukemias.
What are the adverse reactions of the nitrogen mustard drugs?
- immunosuppresive
- carcinogenic
- teratogenic
Describe Mechlorethamine.
- a nitrogen mustard drug
- also called mustargen and mustine
- a nitrogen based analogue of mustard gas
- most reactive of the group
- used in combination with other drugs - MOPP to treat Hodgkin’s disease
- can cause infertility, bone marrow depression and GI toxicity (toxic to proliferating cells)
What is MOPP?
A combination of drugs including Mechlorethamine, Oncovin, Prednisone and Procarbazine that is used to treat Hodgkin’s disease.
What is another name for Oncovin?
Vincristine.
Hodgkin’s disease is treated with what?
The drugs MOPP.
Describe Cyclophosphamide.
- a nitrogen mustard drug
- also called Cytoxan, Neosar
- broad spectrum - given orally and IV
- is a prodrug that is converted to phosphor amide mustard and acrolein by cytochrome P450
- causes cross-linking of DNA via N7 of guanine
What is Cyclophosphamide used for?
- non-neoplastic diseases like nephrotic syndrome
- non-Hodgkin’s lymphomas
- maintenance therapy for acute lymphoid leukemia (ALL)
- adjuvant therapy in breast cancer
- carcinoid
- neuroblastoma
What are the adverse side effects of Cyclophosphamide?
- bone marrow suppression
- alopecia
- GI disturbances
- hemorrhagic cystitis
Describe Ifosfamide.
- an analog of cyclophosphamide
- also called Ifex
- activated in the liver by ring hydroxylation
What is Ifosfamide used for?
- used as part of multi drug regimen to treat germ cell testicular cancer, pediatric and adult sarcomas and other cancers such as cervical, lung, bone, ovarian and breast
- used in combination with Mesna to reduce its urinary toxicity
What are the adverse side effects of Ifosfamide?
- similar to cyclophosphamide but with greater platelet suppression
- severe urothelial damage and internal bleeding (if not used with Mesna)
Another class of drugs that are alkylating agents is the Nitrosoureas. What is their MOA?
They spontaneously degrade to form 2-chloroethylcarbonium ion which liberates isocyanates that attach carbamoyl groups to lysine residues of proteins. They also cross link DNA strands and break DNA strands.
What are the adverse side effects of Nitrosoureas?
- highly carcinogenic and mutagenic
- cause profound, cumulative myelosuppression
- cause renal failure with long-term use
- cause alopecia
- are hepatotoxic
- cause pulmonary toxicity
Describe Carmustine, Lomustine and Semustine.
- a nitrosoureas
- exhibit high lipophilicity - can cross BBB
- both lomustine and semustine are orally effective
- used to treat brain tumors such as gliomas, glioblastoma multiform, medulloblastoma, astrocytoma
- used to treat GI neoplasms
- alternative drugs in treating Hodgkin’s disease
Describe Streptozotocin.
- a nitrosourea
- water soluble but not orally effective
- particularly toxic to pancreatic islet cells
- used to treat insuloma (pancreatic islet cell carcinoma, carcinoid, excessive insulin secretion)
- used to treat metastatic cancer of pancreatic islet cells
- can be used to cause experimental diabetes in lab animals
What is the MOA of Streptozotocin?
It methylates RNA and DNA and is particularly toxic to pancreatic islet cells.
Describe Bisulfan.
- an alkyl sulfonate
- selectively myelosuppressive by inhibiting granulocytopoiesis
- used to treat chronic myelogenous leukemia (CML) and other myeloproliferative disorders
- causes myelosuppression
- causes ‘Busulfan lung’ which is rare but fatal pulmonary fibrosis so is contraindicated in pt’s with pulmonary disease/condition
Describe the Antimetabolite class of anti-cancer drugs.
- structurally similar to important endogenous molecules in the synthesis of DNA and RNA
- has three general groups
- act as enzyme inhibitor
- they are S-phase specific because they slow down the synthesis of nucleic acids
What are the 3 general groups of Antimetabolite cancer drugs?
- purine analogs
- pyrimadine analogs
- folic acid analogs
Name one purine analog cancer drug. What is it’s MOA?
6- Mercaptopurine (6-MP)
This drug is a structural analog of adenine that is activated by an enzyme (HGPRT) to convert to a nucleotide called 6-TIMP. 6-TIMP inhibits the conversion of IMP to adenine and guanine and blocks the first step in de novo synthesis of purines - thus blocking DNA replication and RNA transcription.
What is the clinical use of 6-MP?
It is used for maintenance therapy of acute lymphoid leukemia (ALL) in children.
What are the adverse effects of 6-MP?
- bone marrow suppression
- immunosuppression
- GI disturbances
- liver toxicity
How does the body develop resistance to 6-MP?
- increased breakdown of 6-TIMP by alkaline phosphatase
2. decreased activation of the drug via decreased or lack of the enzyme HGPRT
Name another Purine analog drug. What is it’s MOA?
6-Thioguanine
This drug is converted to 6-TGMP by the enzyme HGPRT. 6-TGMP becomes incorporated into DNA as dTGTP. It is also an enzyme inhibitor.
What is 6-Thioguanine used for?
It is used to treat leukemias - especially acute granulocytic leukemia. For treatment of AGL it is used in combo with Cytarabine.
What are the adverse effects of 6-Thioguanine?
- bone marrow suppression
- mild nausea
- resistance can develop - via decreased conversion of the prodrug form
Describe 5- Fluorouracil.
- a Pyrimidine antagonist
- bioactivated to 5FdUMP in the body
- 5FdUMP covalently complexes with folic acid
- the complex then inhibits thymidylate synthesis causing decreased dTMP and thus termination of DNA synthesis
- requires enzymatic conversion to a nucleotide via ribosylation and phosphorylation to exert its cytotoxic activity