Hormonal Antineoplastics Flashcards
What are the two general kinds of cancers that rely on steroids for growth?
androgen-sensitive prostate cancers
estrogen-sensitive breast cancers
What are the two GENERAL strategies for hormonal antineoplastics in these cancers?
- decrease the steroid concentration
2. decrease the steroid action
What are the three strategies to reduce steroid concentration?
- inhibit LH and FSH secretion with either GnRH agonists or antagonists
- Block androgen biosynthesis with 5alpha reductase inhibitors of 12 alpha hydrosylase inhibitors
- Aromatase inhibitors
What are the two GnRH analogues used to inhibit LH and FSH secretion?
Goserelin and leuprolide
In the short term, what do these GnRH agonists cause?
increase in testosterone or estrogen
leads to a flare response which includes increase cancer growth and increase in bone pain if there are mets
In the long term, what do these GnRH agonists cause?
eventually, they lead to downregulation of the GnRH receptors, so you get decreased GnRH response and decreased testosterone/estrogen production
How does the response to GnRH antagonists differ from that?
The antagonists work right away and you don’t have that flare response
but they’re waaaay more expensive - is it worth it?
About how long does it take for Goserelin and Leuprolide to work?
about 7-10 days to get past the flare response
given in depot form
What do we use Goserelin an dleuprolide for?
- advanced prostate CA
2. premenopausal women with ER+ breast cancer
We already talked about the flare response as a toxicity. What are some others?
pain at injection site
hot flashes and other decreased hormone effects
What is the GnRH antagonist we know?
Degarelix
What are the side effects of Degarelix?
generally well tolerated - some injection site reaction only
What are the two 5alpha-reductase inhibitors?
dutasteride
finasteride
What is the mechanism of action for dutasteride and finasteride?
they block 5alpha-reductase, so you don’t get conversion of testosterone to DHT (which produces better tumor growth than testosterone)
What are the main uses for finasteride and dutasteride?
BPH and male pattern baldness
but also off label for prevention of prostate cancer in men with high PSA values
What are the side effects of finasteride and dutasteride?
impotence!
but a less degree of bone density loss compared to other meds and less muscle wasting
can have a high degree of teratogenicity if a pregnant woman handles the capsule
What is the 17alpha-hydroxylase inhibitor?
abiraterone acetate
How does abiraterone acetate work?
It blocks an earlier stage of androgen synthesis
but doesn’t interfere with conversion of pregnenolone, so you don’t get low cortisol side effects
What do we use abiraterone acetate for?
metastatic prostate cancer resistant to other androgen-blocking regimens
What are the two classes of aromatase inhibitors? Which class is reversible?
Steroid analogues (of androstenedione) non-steroidals (reversible)