Antineoplastic 1 Flashcards
When cancer cannot be cured what are the goals of treatment?
- Shifts to palliation
- Amelioration of symptoms
- Preservation of quality of life
Types of Systemic Cancer Treatments?
- Conventional “cytotoxic” chemotherapy agents
- Targeted agents: Biologics (antibodies or cytokines)
- Hormonal therapies
- Biologic therapies: manipulate the host-tumor interaction in favor of the host.
Define Gompertzian tumor growth:
The growth fraction of a tumor declines exponentially over time.
Total Kill Hypothesis:
- Single cancer cell can multiply and kill the host
- For microbial infections a “3-log kill” by antibiotics may be sufficient to allow host defense mechanisms to eradicate the infection.
- For successful cancer treatment: All of the cancer cells must be killed.
Log-Kill Model by Skipper states what for a given dose of a drug?
It kills a constant fraction of cells, not a constant number, regardless of the cell numbers present.
Describe adjuvant chemotherapy?
Assumes the presence of undetectable cell masses after the initial surgical therapy that are capable of producing tumor relapse.
Clinically sequential use of drugs that works per Gompertzian growth.
- Cell-cycle nonspecific agents (cyclophosphamide) to bring down the mass.
- When tumor shrinks, proliferation begins.
- Cell-cycle specific agent (methotrexate)
- Kills the cell as it tries to proliferate.
Vinca Alkaloids work by what mechanism?
- Inhibition of tubulin polymerization, which disrupts assembly of microtubules, an important part of the mitotic spindle.
- Causes mitotic arrest at Metaphase, cell division stops, cell dies.
- Bind to B-tubulin and prevents interaction with a-tubulin.
What is the principal mechanism of resistance to Vinca Alkaloids?
Increased P-Glycoprotein
What are the three vinca alkaloids mentioned and what is said of them?
- Vincristine
- Neurotoxic
- Prednisone is useful in childhood leukemias.
- Vinblastine:
- Myelosuppressive (bone marrow suppression)
- Metastatic testicular cancer and Hodgkin’s lymphoma.
- Vinorelbine
Describe the mechanism and outcome of Taxanes?
- Hyper-stabilizes microtubule structure (freezes them)
- Taxanes bind to the B-subunit of tubulin, the resulting microtubule/taxane complex does not have the ability to disassemble.
- This adversely affects cell function and leads to apoptosis.
What Taxane is especially known for stocking and glove neuropathy?
Paclitaxel
What cancers have Taxanes become central treatments of?
Metastatic ovarian, breast, lung, GI, genitourinary, head and neck cancers.
What is the prototype of Epothilones and what is it approved for?
Ixabepilone
Metastatic Breast Cancer
What is the mechanism for Epothilones?
- They bind to B-tubulin and trigger microtubule nucleation at multiple sites away from centriole.
- Chaotic stabilization triggers cell cycle arrest at G2-M interface and apoptosis.