Treatment Options for Docetaxel refractory patients

Winston W Tan MD FACP

Senior Consultant Hematology/Oncology

Genitourinary Oncology

Mayo Clinic College of Medicine

Learning Objectives

• Describe the mechanisms by which androgen receptor signaling affects prostate cancer growth despite castrate levels of testosterone

• Summarize therapeutic options for castration-resistant prostate cancer (CRPC), including the role of chemotherapy, and emerging therapies

• Apply clinical evidence for best treatment strategies in CRPC to improve patient care

S9364: Nadir PSA Level Predicts Survival in Patients With Metastatic Disease Treated

With Primary ADT

Hussain M, et al. J Clin Oncol. 2006;24:3984-3990; with permission.

CRPC: Evolving Paradigm

• Androgen receptor (AR) signaling is a key factor in prostate cancer growth despite castrate serum levels of testosterone– Caused by a number of different factors:

• Receptor overexpression/amplification• AR mutations• Increased AR ligand expression• AR coactivators• Ligand-independent AR activation

• AR signaling leads to tumor growth and proliferation despite castrate androgen levels

Gelmann EP. J Clin Oncol. 2002;20:3001-3015.

• CRPC: A working definition– Evidence of PSA and/or radiographic disease

progression in the setting of castrate levels of testosterone (≤50 ng/dL)

CRPC: Evolving Paradigm

Chemotherapy for AIPC

• Mitoxantrone combined with prednisone is palliative with a median survival of 10-12 months

• Phase I/II studies show a trend towards improved median survival with the combination of Estramustine/Docetaxel

>Time to progression 5-6 months >Median survival 20-23 months

Petrylak et al. Semin Onc. 1999; 26(Suppl 17):28-33. Savarese et al. JCO. 2001;19:2509-2516.

Petrylak et al. Eur Urol Suppl. 2002;1:15-23.

Management of Metastatic CRPC: Chemotherapy

• The standard of care for CRPC changed from mitoxantrone/prednisone to docetaxel/prednisone based on SWOG 99-16 and TAX-327 studies1,2

SWOG 99-161

RandomizedN=770

- Mitoxantrone 12 mg/m2; Day 1- Prednisone 5 mg BID; 21-day cycles

- Docetaxel 60 mg/m2 ; Day 2 + dexamethasone 20 mg TID; Days 1–2- Estramustine 280 mg TID;Days 1–5 of 21-day cycles

1. Petrylak DP, et al. N Engl J Med. 2004;351:1513-1520.2. Tannock TF, et al. N Engl J Med. 2004;351:1502-1512.

TAX-3272

Randomized

- Prednisone 10 mg QD - Mitoxantrone 12 mg/m2 every 3 wks;every 21 days up to 10 cycles

- Prednisone 10 mg QD- Docetaxel 30 mg/m2 weekly;5 wks on, 1 wk off × 6 cycles

- Prednisone 10 mg QD- Docetaxel 75 mg/m2 every 3 wks

N=1006

Management of Metastatic CRPC: Chemotherapy

• SWOG 99-16– Docetaxel/estramustine improved median survival by

2 months compared with mitoxantrone/prednisone

Petrylak DP, et al. N Engl J Med. 2004;351:1513-1520; with permission.

HR: 0.80

Management of Metastatic CRPC: Chemotherapy (TAX-327)

• Docetaxel therapy led to improved survival and rates of response in terms of pain, PSA level, and quality of life compared with mitoxantrone/prednisone

Tannock TF, et al. N Engl J Med. 2004;351:1502-1512; with permission.

HR: 0.83, P=0.03

Management of Metastatic CRPC: Chemotherapy

• Long-term follow-up of TAX-327:– 310 additional deaths at 5 years

D3P D1P M+P

Median survival 19.2 months 17.8 months 16.3 months

Difference in survival

P=0.004 P=0.004

Patient survival >3 years

18.6% 16.8% 13.5%

D3P=docetaxel every 3 weeks; D1P=weekly docetaxel; M+P=mitoxantrone/prednisone therapy.

Berthold DR, et al. J Clin Oncol. 2008;26:242-245.

AR-Targeting Therapies: Abiraterone Acetate

• Inhibits the CYP 17 (17α-hydroxylase and C17,20-lyase) dual enzyme complex, which is principally responsible for androgen synthesis

• Results in PSA decline, tumor response, and improvements in ECOG performance scores

Patient Population NPSA Decline

≥50%

Tumor Response:

Partial Response

Tumor Response:

Stable Disease

ECOG PS Improvement

≥1 level

CRPC, chemotherapy naive1 33 24 (73%) 9 (27%) 19 (58%) 8 (61.5%)

CRPC, prior docetaxel2 47 24 (51%) 6 (13%) 25 (53%) 11 (35%)

CRPC, prior docetaxel3 58 45% 39 (64%) – 16 (50%), n=32

ECOG PS, Eastern Cooperative Oncology Group Performance Status

1. Ryan C, et al. J Clin Oncol. 2009;27(suppl):245s (abstract 5046). 2. Reid AH, et al. J Clin Oncol. 2009;27(suppl):246s (abstract 5047). 3. Danila DC, et al. J Clin Oncol. 2009;27(suppl):246s (abstract 5048).

AR-Targeting Therapies: MDV3100

• Novel small-molecule AR antagonist• Binds the AR with greater relative affinity than the

clinically used antiandrogen bicalutamide• Reduces the efficiency of its nuclear translocation and

impairs both DNA binding to androgen response elements and recruitment of coactivators

• Results of recent phase I/II study:– PSA declines of >50% observed in 43% of CRPC patients

• Phase III trial in the post-docetaxel setting ongoing

Scher HI, et al. Lancet Oncology. 2010;375:1437-1446.

AR-Targeting Therapies: BMS-641988

• Hypothesized to slow growth of prostate cancer by blocking action of androgens

• Found to have superior potency and efficacy compared with bicalutamide1

• Found to promote an expression profile more similar to castration than bicalutamide1

• Awaiting data from 2 completed Phase I trials for CRPC– Randomized multicenter dose-escalation study (United States)2

– Nonrandomized multicenter, open-label study (Japan)3

1. Attar RM, et al. Proc Amer Assoc Cancer Res. 2006;47:Abstract 5345.2. Clinical Trials.gov. www.clinicaltrials.gov/ct2/show/NCT00326586.3. Clinical Trials.gov. www.clinicaltrials.gov/ct2/show/NCT00644488.

Management of Metastatic CRPC: Docetaxel-Refractory Patients

• No standard of care• Salvage chemotherapeutic regimens include:

– Mitoxantrone and/or ixabepilone plus prednisone1-3

– Carboplatin plus docetaxel4,5

1. Thomas C, et al. Urologe A. 2009;48:1070-1074.2. Rosenberg JE, et al. Cancer. 2007;110:566-563.3. Rosenberg JE, et al. J Clin Oncol. 2009;27:2772-2778.4. Reuter CW, et al. World J Urol. 2010;Mar 14 [Epub ahead of print]5. Ross RW, et al. Cancer. 2008;112:521-526.

Management of Metastatic CRPC: Docetaxel-Refractory Patients

• Mitoxantrone or ixabepilone plus prednisone

MP=mitoxantrone/prednisone.Rosenberg JE, et al. Cancer. 2007;110:566-563; with permission.

Management of Metastatic CRPC: Docetaxel-Refractory Patients

• Carboplatin/docetaxel therapy– Recent data suggest that platinum salts may be effective when

combined with taxanes (docetaxel)

Progression-free survival Overall survival

Ross RW, et al. Cancer. 2008;112:521-526; with permission.

Management of Metastatic CRPC: Docetaxel-Refractory Patients

• Cabazitaxel– Novel taxane that appears to be active in docetaxel-

resistant tumor cell lines– Evaluated in the phase III TROPIC study

• Median survival cabazitaxel treatment group vs mitoxantrone treatment group

• Improved progression-free survival and tumor response rates

Sartor AO, et al. [Abstract No. 9]. 2010 Genitourinary Cancers Symposium; San Francisco, CA.

TROPIC: Phase III Registration Study

Primary endpoint: OSSecondary endpoints: Progression-freesurvival (PFS), response rate, and safety

Inclusion: Patients with measurable disease must have progressed by RECIST; otherwise must have had new lesions or PSA progression

cabazitaxel 25 mg/m² q 3 wk + prednisone* for 10 cycles

(n=378)

mitoxantrone 12 mg/m² q 3 wk+ prednisone* for 10 cycles

(n=377)*Oral prednisone/prednisolone: 10 mg daily.

Stratification factorsECOG PS (0, 1 vs. 2) • Measurable vs non-measurable disease

mCRPC patients who progressed during and after treatment with a docetaxel-based

regimen (N=755)

Sartor AO, et al. Presented at the 2010 Genitourinary Cancers Symposium. March 5-7, 2010; San Francisco, CA.

TROPIC Primary Endpoint: Overall Survival (Intent-to-Treat Analysis)

MP 377 300 188 67 11 1

CBZP 378 321 231 90 28 4

Numberat risk

Proportionof OS (%)

15.112.7Median OS (months)

0.59–0.8395% CI<.0001P Value

0.70Hazard Ratio

CBZPMP

Sartor AO, et al. Presented at the 2010 Genitourinary Cancers Symposium. March 5-7, 2010; San Francisco, CA.

Approved by FDA: June 2010

• Conclusions from the TROPIC trial– Cabazitaxel demonstrated a statistically and clinically significant

overall survival improvement compared with mitoxantrone• 30% risk reduction of death (HR = 0.70, P<.0001)

• Median overall survival improvement in favor of cabazitaxel– Benefit was consistent across subgroups

– Progression-free survival, relative risk, and time to progression were also significantly improved

– Safety profile was predictable and manageable• Neutropenia, diarrhea, fatigue and asthenia were the most common

adverse events

Management of CRPC: Docetaxel-Refractory Patients

Sartor AO, et al. Presented at the 2010 Genitourinary Cancers Symposium. March 5-7, 2010; San Francisco, CA.

Docetaxel in Novel Combination Regimens for HRPC

• Docetaxel + Thalidomide• Docetaxel + Calcitriol (Vitamin D)• Docetaxel / Estramustine + Herceptin• Docetaxel + Exisulind

Satraplatin

• Second line• 950 patients• Satraplatin/prednisone vs prednisone• 40% decrease in TTP• 9.7 vs 11 weeks TTP

• Petrylak et al ASCO (prostate) 2007

Satraplatin

• Satraplatin is an orally active platinum compound that has significant activity in cisplatin-resistant tumor models. Activity in prostate cancer was suggested in early clinical studies .

• Satraplatin was evaluated more extensively in a phase III trial, in which 950 men who had progressed after first-line chemotherapy for castrate-resistant prostate cancer (51 percent of whom had been treated with docetaxel) were randomly assigned to prednisone plus either satraplatin (80 mg/m2 for five days every five weeks) or placebo . Final results of this trial were presented at the American Society of Clinical Oncology (ASCO) meetings in 2008.

• Progression-free survival (PFS) was significantly increased in patients assigned to satraplatin compared to placebo (one-year PFS rate 17 versus 7 percent, median PFS 11.1 versus 9.7 weeks, hazard ratio [HR] 0.67, 95% CI 0.57-0.77).

• There was no difference in overall survival (61 weeks on both treatment arms, HR 0.95, 95% CI 0.84-1.15).

• Treatment was generally well tolerated, with myelosuppression being the major cause of grade 3 or 4 adverse events (neutropenia, thrombocytopenia, and anemia in 22, 23, and 12 percent of satraplatin-treated patients, respectively).

Antiangiogenic Agents: Bevacizumab

• CALGB 90401– Phase III trial comparing docetaxel/prednisone with or without bevacizumab in

hormone-resistant prostate cancer1

– Preliminary data suggest that this trial did not reach its primary endpoint of overall survival2

• Data to be presented at the 2010 American Society of Clinical Oncology (ASCO) annual meeting, June 4 to 8, 2010.

- Hormone refractory prostate cancer- Metastatic disease-Testosterone <50 ng/mL- No prior chemotherapy

N=1020

Every 3 weeks:Docetaxel: 75 mg/m2 IV on Day 1 +Prednisone: 5 mg BID PO on Days 1-21 +placebo IV on Day 1

Every 3 weeks:Docetaxel: 75 mg/m2 IV on Day 1 +Prednisone: 5 mg BID PO on Days 1-21 +Bevacizumab: 15 mg/kg IV on Day 1

1. Clinicaltrials.gov. www.clinicaltrials.gov/ct2/show/NCT00110214.2. Kelly WK, et al. J Clin Oncol. 2010;28:7s (Abstract LBA4511).

Antiangiogenic Agents: Sunitinib• Tyrosine kinase inhibitor currently approved for renal cell

carcinoma and gastrointestinal tumors• Several trials of sunitinib in CRPC:

Author Patients Outcomes

Dror Michaelson M, et al. 20091

CRPCGroup A (n=17): chemotherapy-naïve Group B (n=17): docetaxel-resistant

-1 confirmed PSA response in each group- 8 and 7 men had stable PSA (week 12) in groups A and B, respectively- Improvements on radiographic imaging in the absence of post-treatment PSA declines

Sonpavde G, et al. 20102

Metastatic CRPC (post-docetaxel progression)

- N=36- 12.1% had ≥50% decline in PSA- 21.2% had ≥30% decline in PSA- 44% demonstrated improvements on imaging- 13.6% reported declines in pain scores ≥2 points

1. Dror Michaelson M, et al. Ann Oncol. 2009;20:913-920.2. Sonpavde G, et al. Ann Oncol. 2010;21:319-324.

Bone-Targeting Therapies: ZD4054

• Endothelin-A receptor antagonist• Recent multinational phase II trial in metastatic CRPC1

– Primary endpoint of time to progression not achieved– Improvement in overall survival observed in both treatment arms

• Second phase II trial in metastatic CRPC currently underway2

Placebo (n=107)

ZD4054 10 mg (n=107)

ZD405415 mg (n=98)

Time to progression 3.7 4.6 3.8

P value 0.553 0.702

Overall survival 17.3 24.5 23.5

P value 0.008 0.052

Time to PSA progression 2.8 3.7 2.9

P value 0.743 0.273

1. James ND, et al. Eur Urol. 2009;55:1112-1123.2. Clinicaltrials.gov. www.clinicaltrials.gov/ct2/show/NCT01000948.

Bone-Targeting Therapies:Denosumab

• Monoclonal antibody that acts against receptor activator of nuclear factor-κB ligand to improve bone mineral density and fractures

• Useful in CRPC, as ADT is associated with bone loss and increased risk for fracture

• Recent study in men receiving ADT for prostate cancer1

• Current phase III trial underway in non-metastatic CRPC patients undergoing ADT2

Cumulative Incidence of New Vertebral Fracture

0

2

4

6

12 months 24 months 36 months

Placebo

Denosumab

1.9

0.3

3.3

1.0

3.9

1.5

1. Smith MR, et al. N Engl J Med. 2009;361:745-755. 2. Clinicaltrials.gov. www,clinicaltrials.gov/ct2/show/NCT00838201.

Immunomodulatory Therapies:Lenalidomide

• Highly potent immunomodulatory derivative of thalidomide

• Potentiates the action of paclitaxel in vitro against prostate cancer cell lines in co-culture with mononuclear cells

• Phase I study in metastatic CRPC patients:– Combined with weekly paclitaxel– PSA declines by >50% in 2 of 7 evaluable patients– Frequent dose-limiting toxicity

Mathew P, et al. Cancer Chemother Pharmacol. 2010;65:811-815.

Management of Metastatic CRPC: Integrating Novel Therapeutics

• Current therapeutic paradigm– Second-line hormonal therapy– Docetaxel-based chemotherapy– Retreatment with docetaxel, mitoxantrone,

investigational therapy, supportive care

Custersin studies

• Phase III of docetaxel vs docetaxel plus custerin docetaxel after initial response and then on progression is randomized in patient with castrate resistant prostate cancer with metastasis with symptomatic pain

• Phase III first line same arms

MDV Phase III studies

• Phase III AFFIRM study MDV 3100 vs placebo in patients who have progressed on docetaxel

• Phase III study on chemotherapy naïve patients also being studied

Summary

• Metastatic CRPC management will likely evolve over the next 12–24 months with the introduction of novel agents, including AR-targeting agents and new chemotherapies

• Introduction of new agents will challenge the clinical research community to design and conduct studies that bring some clarity into optimal use/sequence of these agents

Thank You