Session 10: Cancer Chemotherapy Flashcards
What is imatinib used for?
Chronic myeloid leukaemia
It is a Bcr-Abl tyrosine kinase inhibitor.
Explain when chemo works in the cell cycle.
Chemo only works if the cell is in the cycle, and not in G0!.
Explain the fractional cell kill hypothesis.
You give chemotherapy in cycles. The timing of administration is tailored to the recovery of the cells of the bone marrow.
Tumour cells will not recover as fast as the bone marrow does. This means that there is minimal suppression of bone marrow but still a gradual decrease of tumour growth/cell number.
Give examples of chemotherapies.
Antimetabolites
Alkylating agents
Intercalating agents
Spindle poisons
Platinum compounds
Explain the mechanism of action of platinum compounds.
There is formation of platinated inter- and intrastrand adducts.
An example is an oxaliplatin adduct which will lead to the inhibition of DNA synthesis.
Give examples of antimetabolites.
5-fluorouracil
Methotrexate
Explain the action of methotrexate.
Inhibits dihydrofolate reductase which inhibits the conversion of dihydrofolate to its active form tetrahydrofolate.
This leads to impairment of DNA synthesis.
Explain the action of 5-fluoruracil.
5-fluorouracil inhibits thymidylate synthase (TS) which converts dUMP into dTMP.
This inhibits the synthesis of DNA.
Give examples of spindle poisons.
Taxoids/Taxanes
Vinca alkaloids
Explain the mechanism of action of taxoids/taxanes.
Promotes the assembly (polymerisation) of microtubules (which are supposed to pull sister chromatids apart).
Also prevents the disassembly (depolymerisation) of microtubules.
This leads to too much formation of microtubules and the cell becoming too rigid to divide.
This means it inhibits mitosis.
Explain the mechanisms of resistance of alkylating agents.
A pump will recognise the alkylating agent and pump out the alkylating agent in order to decrease the entry/increase exit of the alkylating agent.
There can also be inactivation of the agent by glutathione inside the cell.
There can also be enhanced repair of DNA lesions that are produced by the alkylation.
Explain the mechanism of action of alkylating agents.
There is a cross linkage between the DNA strands.
This leads to DNA replication not being possible.
The predicted response is different within the same cancer (not only between different).
What is the predicted response based on?
Performance score
Clinical stage of cancer
Prognositc factors or score
Molecular or cytogenetic markers
Ways to administer chemo
IV
PO
SC
Into a body cavity such as bladder
Intralesional
Intrathecal
Topic
IM
Give examples of IV pumps.
PICC line
Hickman line
Give common side effects of chemotherapy.
Alopecia
Mucositis
Nausea/Vomiting
Diarrhoea
Cystitis
Sterility
Cardiotoxicity
Myelosuppression
Pulmonary fibrosis
Neuropathy
Myalgia
Thrombophlebitis
Give chemotherapy ADRs due to effect of treatment on the tumour.
Rapid tumour lysis leading to hyperuricaemia.
This causes precipitation of urate crystals in the renal tubules.
This leads to acute renal failure
GI perforation can happen at the site of tumour in e.g. lymphoma.
DIC can happen in treating acute myeloid leukaemia as well.
Explain why vomiting might occur in chemo.
Direct action of chemotherapy drugs on the central chemoreceptor trigger zone.
There are 3 patterns of emesis in chemo.
Acute phase 4-12 hours
Delayed onset 2-5 days later
Chronic phase - may persist up to 14 days
Give chemo drugs which will cause a lot of alopecia.
Doxorubicin
Vinca alkaloids
Cyclophosphamide
Give an example of a chemo with minimal alopecia.
Platinum compounds