Flashcards in Exam 3: Antineoplastic agents Deck (53):
A disease of cell proliferation where normal cells are transformed by genetic mutation into cells with dysregulated growth.
What are the 3 steps of Carcinogenesis:
Define the transformation step of carcinogenesis:
- A cell with normal growth changes into a cell with dysregulated growth (Malignancy)
- Genetic Damage
○ Mutations that alter growth and repair
○ Alterations in or loss of regulatory proteins
Define the Proliferation phase of Carcinogenesis
- Growth of transformed cells into a tumor
- Increase in the number of cells
Most antineoplastic drugs target what activity?
Target dividing cells
Which cells respond best to chemotherapy?
- Small, rapidly dividing cells respond best
- Normal cells also rapidly divided and are also subjected to effects of chemo
Define Dose-limiting toxicity
The dosage being administered is limited because of the possibility of causing toxicity
What is the challenge of chemotherapy?
To give an adequate dose to kill the cancer cells without killing too many healthy cells
Define the Metastasis phase of Carcinogenesis
- Cancer cells acquire the ability to invade tissues throughout the body
- Tumor cells mutate which allows them to invade into tissues and vessels, body cavities, etc. and grow in a new location.
What must be taken into consideration before administering chemotherapy to a patient with metastatic lesions?
- As these cells gain mutations, their response to chemotherapy may change. (altered receptors)
- The original tumor may respond well to chemotherapy, but metastatic lesions may be less response = poor prognosis
Most chemotherapy agents interfere with what carcinogenesis phase?
When are cancer cells most sensitive to chemotherapy drugs?
- When the cells are actively going through the cell cycle
- Metabolically active cells are more susceptible to drugs that interfere with cell growth and division
What is the tumor suppressor gene that senses DNA damage and arrests the cell cycle?
This allows time for the damage to be repaired
If a cell fails to repair damage due to chemotherapy, what occurs?
- The cell dies by a biochemically-driven programmed cell death
What is the action of p53?
- Helps to suppress cancer; anti-cancer mechanisms.
- Activate DNA repair proteins
- Hold cell cycle at G1/S regulation point so that DNA repair proteins will fix damage, then cell allowed to continue cell cycle.
- Can initiate apoptosis if damage is irreparable
- Induce growth arrest.
What things might induce p53?
1. UV radiation
3. DNA damaging drugs
What occurs if p53 gene is damaged?
Tumor suppression is severely reduced.
Which type of cells are "highly responsive to chemotherapy"?
- Cancer cells that express p53
*includes leukemias, lymphomas, testicular cancer
Which cells are minimally responsive or resistant to DNA-damaging chemotherapy drugs?
- Cancer cells that acquire a mutation in p53
*include pancreatic, lung and liver cancers
T or F, Every malignant cell MUST be destroyed to "cure" the cancer
True, a single malignant cell can expand clonally to give rise to a tumor.
When administering chemotherapy, is there a specific dosage or cycle number that all therapies follow?
Multiple cycles of chemotherapy must be given at the HIGHEST tolerable dose with the most frequent tolerable interval to achieve a cure
Chemotherapy is under what order of kinetics?
- First-order kinetics
A constant fraction of tumor cells is killed with each cycle of chemotherapy
Which type of tumors do not respond well to chemotherapy?
- Solid tumors
Slower growth/division of these cells
Solid tumors often require what type of treatment?
Often require radiation and/or surgery as well as chemotherapy.
- Resistance to chemotherapy drugs often develops!
- Justification for using combination drug therapy
Explain Combination Chemotherapy
(B) Includes drugs that act on different molecular targets, at different phases of the cell cycle and with different dose-limiting toxicities.
Explain the benefits to Combination Chemotherapy
- This reduces the emergence of drug resistance
- Allows each individual drug to be given at its highest tolerable dose.
- (B) Some regimens offer SYNGERGISTIC BENEFITS
- (B) Typically use intermittent dosing
Examples of cancers that require combination chemotherapy
- Hodgkin's disease
- Testicular cancer
- Breast cancer
- Ovarian cancer
- Cervical cancer
- Bladder cancer
- Lung cancer
- Cancer of head and neck
The current emphasis in cancer treatment is use of what therapy? Why?
- Drug Combination therapy
- It takes into account phase of the cell cycle
- Potential synergistic action
- Increases efficacy
- Decreases cell resistance
Define Cell-Cycle specific drugs
Drugs that affects one phase
Define Cell-Cycle non-specific drugs
Drug affects any/all phases
T or F, Drugs for chemotherapy are safe for humans to consume (B)
- False, they are not safe.
(B) They lack specificity. They affect malignant cells as well as rapid but normally proliferating cells
Name some examples of normal proliferating cells that chemotherapy drugs also attack
Bone marrow, Skin & intestinal mucosa
(B)What are the signs of toxicity that appear in the normal cell proliferating areas that are attacked by chemo drugs
- Blood dyscrasias
- Ulcerations of oral mucosa and other sites in GI tract
(B)Mechanism of Alkylating agents
- (B)Transfer alkyl groups to important cell constituents with amino-, sulfhydryl-, carboxyl-, and phosphate- groups
- (B)Alkylate DNA, probably at guanine as the primary mechanism for cell death
- (B)Interfere with DNA, RNA and proteins to prevent cell metabolism and division
What is the primary mechanism for cell death
Alkylate DNA, probably at guanine
Name the major classes of Alkylating agents
1. Nitrogen mustards
2. Alkyl sulfonates
T or F, Susceptibility to infection is common outcome of treatment with alkylating agents
They are mutagenic, teratogenic, oncolytic, myelosuppressive, immunosuppressive and carcinogenic.
Name the 3 given examples of Alkylating agents
1. Cyclophosphamide (Cytoxan)
a. Multiple cancers, bone marrow transplants
2. Ifosfamide (Ifex) = nitrogen mustard
a. Multiple cancers
3. Procarbazine (Matulane)
a. Hodgkin's disease
Role of Antimetabolites
- Serve as fraudulent substrates for biochemical interactions
- Interfere with growth of rapidly proliferating cells
Are Antimetabolites cycle specific or non-specific?
- (B) S phase specific
Name the classes of Antimetabolites
- Folic acid antagonists
- Purine antagonists
- Pyrimidine antagonists
Action of Folic acid antagonists
1. (B) Inhibits DNA synthesis
2. Inhibit nucleic acid synthesis by blocking the enzyme dihydrofolate reductase
Name the Folic acid antagonist drug
- (B) Methotrexate (Rheumatrex, Trexall)
- Used for many cancers; autoimmune diseases
Is methotrexate cell cycle specific or non-specific?
- (B) Cell-cycle specific
Role of Purine antagonists
Inhibit enzymes that convert hypoxanthine ribonucleotide to adenine and xanthine ribonucleotide
Name the purine antagonist drug name
- (B) Mercaptopurine (purinethol)
- Lymphoblastic leukemia
Function of mercaptopurine
Inhibits DNA and RNA synthesis
Is mercaptopurine cell-cycle specific or non-specific
- (B) Cell-cycle specific
Role of Pyrimidine antagonists
Inhibit pyrimidine synthesis
Name the 2 drugs in the pyrimidine antagonist class
1. (B) Fluorouracil (Adrucil) = "5-FU"
2. (B) Cytarabine (Cytosar-U) = "Ara-C"
Function of fluorouracil
- Interferes with DNA synthesis or becomes incorporated into RNA
- Many cancers
Function of cytarabine
Inhibition of DNA synthesis and repair