Anti cancer drugs Flashcards
Target unique structure (or expressed element) or process associated with cancerous cell
Selective toxicity
What is the mechanism of alkylating agents?
Insert alkyl group into DNA structure; cross-link between adjacent bases, particularly guanine bases, as well as proteins; cause stress in molecules leading to strand breaks and apoptosis
Which stage of the cell cycle do alkylating agents target?
generally, cycle non-specific
What does a bifunctional alkylating agent do?
Causes intrastrand linking and cross-linking
Why are cytotoxic antibiotics used in cancer therapy?
Too toxic to use in infectious disease therapy; the cost vs benefit ratio is different in cancer
What is the mechanism of cytotoxic antibiotics?
Inhibit transcription and translation processes
What do antimetabolites do?
Substitute themselves in the DNA synthesis pathway, block DNA synthesis, make molecule non-functional
Which stage of the cell cycle to antimetabolites target?
S phase
What are the three pathways by which antimetabolites may block DNA synthesis?
Folate pathway, pyrimidine base synthesis, purine base synthesis
Which pathway does methotrexate target?
Folate pathway, similar shape to folic acid
What is the mechanism of mitotic poisons?
Inhibit microtubule function so that mitotic spindles don’t form or inhibit topoisomerase
Which stage of the cell cycle to mitotic poisons target?
M phase
Examples of mitotic poisons?
vinca alkaloids (from periwinkle plant), taxanes (European yew tree), etiposide (mandrake)
What is the mechanism of SERM?
Selective oestrogen receptor modulator agonises some oestrogen receptors (for bone development and blood coagulation) and antagonises others (in breast tissue)
What is the mechanism of aromatase inhibitors?
Lower circulating oestrogen (aromatase is used by fat cells to convert precursor substances into oestrogen)
2 drug groups used to treat breast cancer?
SERM and aromatase inhibitors
2 drug groups used to treat prostate cancer?
antiandrogens and gonadotrophin-RH analogues
Mechanism of antiandrogens?
Prevent access to growth factor, stops growth of cancer
Mechanism of gonadotrophin-RH analogues
Gonadotrophin releasing hormone, released from hypothalamus to act on pituitary gland to stimulate LH and FSH; analogue is given repeatedly to change HP axis and cause a decrease in LH secretion
Drug group used to treat blood-borne cancers e.g. leukaemia, lymphoma
Glucocorticoids
Mechanism of action of glucocorticoids
High doses lead to lysis of affected cells