Prostate CA Flashcards
How is testosterone produced?
1) Hypothalamus secrete GnRH to pituitary.
- Pituitary then secrete ACTH to stimulate adrenal to produce adrenal androgens to prostate
- Pituitary also secrete LH to testes to secrete Testosterone
2) Adrenal gland secrete adrenal androgens to stimulate prostate
3) Testes secrete testosterone to stimulate prostate
What is androgen Deprivation Therapy?
Shuts off the production of testosterone
Surgical castration - bilateral orchidectomy Medical castration - GnRH agonist - GnRH antagonist - Estrogen
How effective is ADT?
Very effective
>90% PSA response
>80% tumor response
Not curative
Benefits of surgical castration
Immediate lowering of testosterone level
Cheaper
Adherence assured
Tell me more about medical castration
1) GnRH agonist
- Initial testosterone surge with “flare” response, wary of cord compression and AR
- Examples: Zoladex (Goserelin), Lucrin (Leurpolide), Buserelin, Triptorelin
2) GnRH antagonist
- does not have testosterone surge
3) Estrogen (DES)
- Shuts down Hypothalamic-pituitary-gonadal axis
- avoids some negative side effects of LHRH agonists
0 risk of thromboembolic events
What is the definition of Castration-resistant prostate cancer?
1) Progressive prostate cancer
- rising PSA
- radiographic progression
2) Serum testosterone at castrate levels (
What are the options after failure of CAB?
1) Switching to an alternative anti-androgen
2) Anti-androgen withdrawal
3) Secondary hormones
- Ketoconazole
- DES
- Corticosteroids
4) Chemotherapy
- Mitoxantrone
- Docetaxel
What are the classic secondary hormonal therapies?
They produce modest response rates with unknown impact on survival.
These are:
1) 2nd-line AR inhibitors
- block androgen receptor
- examples include: Flutamide, bicalutamide, nilutamide
2) Adrenal androgen biosynthesis inhibitors
- inhibit non-testicular androgen production
- eg. Ketoconazole
3) Oestrogens
- Reduce testosterone through inhibited LH and LHRH secretion
- peripheral activity
4) Steroids
Tell me about CALGB 9583 by Small in 2004 JCO
Aim: To compare Antiandrogen withdrawal alone vs AAWD+Ketoconazole
2 arms:
1) Anti-androgen withdrawal alone
- on PD, able to have Ketoconazole
2) Anti-androgen withdrawal + Ketoconazole 400mg TDS + Hydrocortisone 30/10
N=260
Results
- No difference in survival
- PSA and Objective responses in 32% vs 7%
- PSA response: 10% in AAWD alone vs 30% in AAWD/K
- Time to PSA progression: 9m in AAWD/K vs 6m
What are the new therapies in met CRPC that improve OS?
1) Chemotherapy
2) 2nd line hormonal agent
3) immunotherapy
4) Bone-seeking targeted agents
What are the contraindications to Abiraterone therapy?
Severe Liver dysfunction
Hypo kalmia
Heart failure
What is the median OS benefit with Abiraterone and enzalutamide?
Abiraterone:
- post Docetaxel = 4.6m
- chemo-naive = 5.2m
Enzalutamide: 4.8m
What are the contraindications to Enzalutamide treatment?
Seizures
What are the contraindications to Sipuleucel-T?
Steroids, narcotics for cancer-related pain, GCSF, Liver mets
What are the contraindications for Radium 223?
Visceral mets
What is the median OS achieved with Radium-223?
3.6m
What is the median OS achieved with Cabazitaxel?
2.4m
Tell me about TAX-327 trial in met CRPC?
Ian Tannock published in NEJM 2004, updated JCO 2008
1000men, CRPC 3 arms: 1) Mitoxantrone + Pred (MP) 2) Docetaxel q3w + Pred (D3P) 3) Docetaxel weekly + Pred (D1P)
Results (updated):
- median survival 16m (MP) vs 18m (D1P) vs 19m (D3P)
- survival rate 13.5% vs 16.6% vs 18.6%
Consistent results across all subgroups
2004 results also reported improved response in terms of:
- pain
- serum PSA level
- QoL
Tell me about the TROPIC study
De Bono Lancet 2010
RCT phase 3 CRPC, PD after Docetaxel-containing regimen
N=750
2 arms:
A) IV Mitoxantrone 12mg/m2 + PO Prednisolone 10 mg
B) IV Cabazitaxel 25mg/m2 + PO Prednisolone 10mg
Q3weekly
Results:
- median survival 13m vs 15m
- median PFS 1.4m vs 2.8m
What are the novel hormonal therapies? And what strategies are they based on?
Eg. Abiraterone and Enzalutamide
Abiraterone: Better suppression of non-testicular testosterone (and related hormones) production)
Enzalutamide: Better inhibition of androgen receptor
What is Abiraterone?
Potent, irreversible inhibitor of CYP17
10x more potent than ketoconazole
Initially used as post-Docetaxel
What is the evidence behind Abiraterone After prior chemo?
De Bono NEJM 2011; COU-AA-301 trial
N=1200, 2:1 ratio. S/p Docetaxel
2 arms:
A) PO Prednisone 5 mg BD + PO Abiraterone Acetate 1000mg or
B) PO Prednisone 5 mg BD + Placebo
Results: (–> updated)
OS: 15m vs11m HR 0.65 –> 16m vs11m
PFS 5.6m vs 3.6m
Time to PSA progression 10m vs 7m –> 8.5m vs 6.6m
PSA Response rate 30% v 6% –> 30% vs 20%
What is the evidence behind Abiraterone before prior chemo?
COU-AA-302
Ryan Charles, fist published NEJM, updated Lancet Oncol 2015
N=1100, No prior chemo
2 arms:
A) PO Abiraterone 1000 mg OM + PO Prednisone 5mg BD
B) PO Placebo + PO Prednisone
Updated results at 4 years (50m)
- Med OS: 45m vs 30m HR 0.8
- Most common G3/4 AE: Cardiac disorders 8% with Abi and 4% with placebo)
Interim results:
- med Radiographic PFS: 16.5m vs 8m HR 0.5
- better time to initiation of chemo, opiate use for cancer-related pain, PSA progression, Decline in PS
How does Enzalutamide work?
1) Binds to the Androgen binding site in the androgen receptor (AR)
2) Inhibition of nuclear translocation of AR
3) Inhibition of the association of the AR with nuclear DNA
Tell me about the AFFIRM study
Aim: To evaluate if Enzalutamide prolongs survival in men with CRPC After chemotherapy
N=1200
After chemotherapy
2:1
2 arms:
A) PO Enzalutamide 160 mg OM
B) PO Placebo
Results:
- Med OS 18m s 13m
- Superiority of Enzalutamide shown in all secondary end points:
» Reduction of PSA by 50% or more: 50% vs 2%
» Soft tissue response rate 30% vs 4%
» QoL RR 40% vs 20%
» Time to PSA progression 8m vs 3m
» Radiographic PFS 8m vs 3m
» Time to 1st skeletal-related event 17m vs 13m HR 0.7
** Seizures reported in 0.6%
What about the PREVAIL study?
Aim: To investigate the survival benefit if Enzalutamide was given before chemo.
N=1700
2 arms:
A) Enzalutamide 160 mg OM
B) Placebo
Results: - rPFS 65% vs 14% - Improved OS 70% vs 60% at cutoff date >> 32m vs 30m - benefitted all secondary end points: >> Time until chemo HR 0.35 >> time until 1st SRE HR 0.7 >> Time until PSA PD HR 0.2 >> Rate of decline of at least 50% of PSA 80% vs 5%
What is the different OSs like between Enzalutamide and Abiraterone?
ENZALUTAMIDE:
- AFFIRM (after chemo): 18m vs 13m
- PREVAIL (before chemo): 32m vs 30m
ABIRATERONE:
- COU-AA-01 (after chemo): 16m vs 11m
- COU-AA-02 (before chemo): 35m vs 30m
Name the side effects of Enzalutamide
Hypertension Seizure risk (0.6%) Fatigue/Asthenia Back pain Hot flush Falls
Why are steroids needed when Abiraterone is given?
To ameliorate symptoms of mineralocorticoid excess:
- fluid overload
- hypo kalmia
- hypertension