Castration-Resistant Metastatic Prostate Cancer: Novel Therapeutics

Robert Dreicer, M.D., M.S., FACPChairman Department of Solid Tumor OncologyTaussig Cancer InstituteCleveland Clinic Professor of Medicine Cleveland Clinic Lerner College of Medicine

Modified from Scher HI and Heller G. Urology 2000;55:323–7

LocallyAdvancedDisease

Rising PSAHormone

Naive

Rising PSACastrate

MetastasesCastrate

Asymptomatic

MetastasesCastrate

Symptomatic

OrganConfined

Metastatic Disease

(De novo)

Clinical States In Prostate Cancer

MetastasesCastrate

Post Docetaxel

Second Line Hormonal Therapy: Next Generation

• Lyase inhibitors: Abiraterone, TAK 700 Inhibits the CYP 17 (17α-hydroxylase and C17,20-lyase) dual enzyme

complex, which is principally responsible for androgen synthesis

• Anti-androgens: MDV 3100 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

Abiraterone: Activity/Toxicity

• Phase I/II multiple studies in castration-resistant metastatic disease, prior ketoconazole and pre/post docetaxel

• Broad anti-tumor activity across these patient subsets• Oral agent, administered with prednisone• Hypertension, fatigue, hypokalemia, glucose intolerance

(secondary to prednisone)

Ryan CJ et al. J Clin Oncol 28:1481, 2010- Danila DC, et al. J Clin Oncol 28:1496, 2010- Reid AH et al, J Clin Oncol 28:1489, 2010

Abiraterone, TAK 700: Clinical Development

• Given evidence of activity, abiraterone rapidly taken into phase III program: Trials completed

• Phase III trial metastatic CRPC post docetaxel 2:1 randomization: abiraterone/prednisone vs

prednisone Primary endpoint: OS

• Phase III trial metastatic CRPC no prior chemotherapy Abiraterone/prednisone vs prednisone Primary endpoint: PFS

• TAK 700 two phase III trials pending activation

Ryan CJ et al. J Clin Oncol 28:1481, 2010

Scher HI, et al. Lancet. 2010;375:1437-46

MDV 3100: Activity/Toxicity

• Phase I/II multiple studies in castration-resistant metastatic disease, prior ketoconazole and pre/post docetaxel

• Broad anti-tumor activity across these patient subsets• Oral agent• Fatigue, mild nausea, anorexia

MDV 3100: Clinical Development

• Given evidence of activity, MDV3100 rapidly taken into phase III program

• Phase III trial metastatic CRPC post docetaxel MDV3100 (160 mg daily vs placebo) Primary endpoint: OS, SE PFS, toxicity

• Randomized Phase II trial metastatic CRPC no prior chemotherapy (planned) MDV3100 vs placebo Primary endpoint: PFS

Endothelin A Antagonists

• The endothelins are a class of peptides expressed in a variety of human tissues, which control vasoconstriction, mitogenesis, nociception, and bone matrix formation

• There is compelling evidence supporting the role of endothelin receptors in the proliferation of prostate cancer and development of bone metastases

• Atrasentan and zibotentan are specific endothelin receptor A antagonists in late stage development in advanced prostate cancer

James ND, et al. Eur Urol 55:1112, 2009 Carducci MA, et al, Cancer 110:1959, 2007

Atrasentan, Zibotentan: Clinical Development

• SWOG 421 Phase III trial of docetaxel/prednisone/placebo vs docetaxel/prednisone/atrasentan front line chemotherapy for metastatic CRPC

• Zibotentan vs placebo in CRPC without metastatic disease

• Zibotentan vs placebo in metastatic CRPC (pain-free or mild pain)

• Docetaxel / prednisone +/- Zibotentan in patients with symptomatic metastatic CRPC

Phase III Trial Comparing Docetaxel + Prednisone With or Without Bevacizumab (CALGB 90401)

Metastatic CRPC

No prior chemotherapy

PS 0-2

DP + BDocetaxel 75 mg/m2 Q 3wk

Bevacizumab 15 mg/kg Q 3wkPrednisone 10 mg daily

DPDocetaxel 75 mg/m2 Q 3wk

Placebo Q 3wkPrednisone 10 mg daily

Metastatic CRPCNo prior

chemotherapyPS 0-2

Results

Kelly WK et al. Proc ASCO 2010;Abstract LBA4511

EndpointDP+B

(N=524)DP

(N=526)HazardRatio p value

Median OS (months) 22.6 21.5 0.91 0.181*

Median PFS (months) 9.9 7.5 0.77 < 0.0001*

≥ 50% decline in PSA 69.5% 57.9% N/A 0.0002

Objective response 53.2% 42.1% N/A 0.0113

Grade 3 or higher treatment-related AE

74.8% 55.3% N/A <0.001

Treatment-related deaths 4.4% 1.1% N/A 0.0014

AE, adverse event; OS, overall survival; PFS, progression-free survival

* Stratified log-rank p value.

Dasatinib

• Dasatinib is an oral tyrosine kinase inhibitor with potent activity against SRC and SRC family kinases, BCR-ABL, platelet-derived growth factor receptor, and c-KIT

• In experimental models, inhibition of SRC has both antitumor effects, directly on prostate cancer cells (proliferation and metastasis), and decreases bone turnover

• Activity in phase II study lead to phase III development

Yu E, et al. Clin Cancer Res 2009 157:421

Dasatinib: Clinical Development

• Randomized Double-Blind Phase III Trial Comparing Docetaxel Combined With Dasatinib (100 mg/day) to Docetaxel Combined With Placebo in Castration-Resistant Prostate Cancer Primary endpoint: OS, SE Rate of change in urinary

N-telopeptide values, time to first SRE, safety and tolerability

Anti CTLA-4 therapy: Ipilimumab

• Ipilimumab is a humanized anti-CTLA-4 antibody• Intriguing evidence of activity in combination with ADT,

GM-CSF• Episodes of autoimmunity, termed ‘immunerelated

serious adverse events’ have been reported including life threatening panhypopituitarism and colitis

Tollefson MK, et al. 2010 Genitourinary Cancers Symposium abst 168

Small EJ, et al. Clin Ca Res 2007 13:1810

Ipilimumab: Clinical Development

• Randomized phase II trial of Ipilimumab with/without GM-CSF in metastatic CRPC-planned

• Phase III in post docetaxel patients ipilimumab vs placebo ongoing

• Phase III trial in asymptomatic metastatic CRPC prior to chemotherapy ipilimumab vs placebo ongoing