Exam 2: Drugs for Breast Cancer Flashcards
what is the most commonly diagnosed cancer in women?
breast cancer
(2nd leading cause of cancer death in women)
what are the three major sub-types of breast cancer?
- Estrogen receptor positive (ER+ most are also PR+) - about 75%
- HER2 +ve - about 15-20%
- Triple negative - 10-20% (BRCA-1 majority)
what type of breast cancer is most responsive to Tamoxifen?
ER+/PR+/HER2-
what type of breast cancer is not responsive to hormone therapy or targeted therapy?
triple negative breast cancer (worst prognosis)
what type of breast cancer has the best prognosis?
ER+
HER2 (less so)
triple negative (worst)
what are the SERMS?
selective estrogen receptor modulators
tamoxifen
toremifene
raloxifene
what are the common adverse effects of tamoxifen?
- menopausal symptoms (hot flashes) - 64% more severe in post-menopausal
- increased risk of DVT/PE
- increased risk of endometrial cancer (after 5 years 4-6 x)
- 30-40% become resistanct after about 5 years
how is tamoxifen metabolized?
pro-drug metabolized by CYP2D6
to endoxifen and 4-hydroxyTAM that bind to ER-alpha
which SERM can be used in pre-menopausal women?
tamoxifen
what SERM is the only one approved by the FDA for metastatic ER+ breast cancer?
Toremifene
(post-menopausal)
what is the current ASCO and FDA position on genotyping for tamoxifen therapy?
It is not recommended
how do leuprolide and goserelin act?
acts as an agonist at the GnRH receptor in the pituitary
what can happen early in treatment with GnRH drugs?
in the first few weeks to months, prior to GnRH receptor down-regulation, increase LH and FSH levels, increase in testosterone/estrogen and a potential transient worsening of cancer symptoms
what are the aromatase inhibitors?
anastrozole
letrozole
exemestane
can you use aromatase inhibitors in pre-menopausal women?
No. They have functional ovaries and their natural axis can overcome the effects of AIs.
what is the distinguishing feature of HER2 positive cells
>6 copies of the HER2 gene - identified by FISH or immunohistochemistry
HER2 activates the RAS-MAPK pathway
what is the chemical name for Herceptin?
trastuzumab
How does trastuzumab work?
it is a monoclonal Ab that selective targets the extracellular HER2 protein to disrupt dimerization with EGFR protein and activation of the RAS-MAPK pathway