Targeting the Androgen Receptor in Castration Resistant Prostate Cancer. Raoul S. Concepcion, MD,FACS IPCU January 2017

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1 Targeting the Androgen Receptor in Castration Resistant Prostate Cancer Raoul S. Concepcion, MD,FACS IPCU January 2017

2 Consultant: Myriad, CUSP, Tolmar, Integra Cloud, Cellay Speakers Bureau: Dendreon, Astellas, Bayer, Janssen, Sanofi, Medivation, Amgen

3 ARS 1 Which of the following is not a complication of ADT? a. Neurocognitive dysfunction b. Cardiovascular dysfunction c. Insulin resistance d. Osteoporosis e. None of the above. They are all complications of ADT

4 ARS 2 The N terminus of the androgen receptor binds the androgen ligand (T/DHT)? a. True b. False

6 Androgens are produced at 3 sites: - Testes - Adrenal gland - Prostate tumor cells

Roger Guillemin 1980s Long-acting synthetic LHRH agonists 2003 First GnRH blocker (abarelix) launched The future New androgen receptor-targeted drugs.

7 Historical Landmarks: 1 st Effective Treatment, 1 st Marker, 2 Nobel Prizes John Hunter 1780-castration 1904 First RP 1938-Acid Phos Huggins -endocrine control Advent of orchiectomy and estrogen treatment (Awarded Nobel Prize for this discovery) 1970s Steroidal and non-steroidal AAs available Nobel Prize: Andrzej Schally, Roger Guillemin 1980s Long-acting synthetic LHRH agonists 2003 First GnRH blocker (abarelix) launched The future New androgen receptor-targeted drugs. AA vaccines, biomarkers, genetic research 1920s RT for PC using radium 1867 First perineal prostatectomy performed 1960s RT established as important treatment for PC 1960s and 70s Synthetic estrogens developed 2004 Docetaxel in combination with prednisone approved 1995 Cryosurgery accepted as a treatment option for recurrent cancer after RT 2008 Degarelix approved in US 2009 ARSI Developed ARSI = Androgen Receptor Signaling Inhibitor; AA = an#androgen; LHRH = luteinizing hormone releasing hormone. Figure courtesy of Dr E. David Crawford

8 Androgen deprivation therapy (ADT) Estrogens (DES) Surgical castration (bilateral orchiectomy) LHRH/GnRH analogs (agonists/antagonists) Antiandrogens Combined androgen blockade (CAB) 17,20 Lyase Inhibitors 8

9 Complications of ADT 1. Hot Flashes 2. Anemia 3. Sexual dysfunction 4. Cognitive dysfunction 5. OSTEOPOROSIS 6. Metabolic Syndrome n obesity n Insulin resistance n Dyslipidemia n Hypertension

Cabozantinib Endothelin receptor inhibitors Atrasentan Zibotentan Angiogenesis inhibitors Bevacizumab Lenalidomide

12 Key phase III clinical trials since 2004 Androgen receptor signaling Abiraterone acetate Enzalutamide Orteronel (TAK-700) Metastasis / invasion inhibitors OGX-011 (1 st line) OGX-011 (2 nd line) TKI inhibitors Sunitinib Dasatinib Cabozantinib Endothelin receptor inhibitors Atrasentan Zibotentan Angiogenesis inhibitors Bevacizumab Lenalidomide Aflibercept Tasquinimod Microtubule inhibitors Cabazitaxel Radiotherapy Radium 223 Immunotherapy Sipuleucel T Ipilumimab Prostvac

Orteronel (TAK-700) TKI inhibitors Sunitinib Dasatinib Cabozantinib Endothelin receptor inhibitors Atrasentan x2

13 Key phase III clinical trials since 2004 Androgen receptor signaling Metastasis / invasion inhibitors Abiraterone acetate OGX-011 (1 st line) Enzalutamide OGX-011 (2 nd line)? Orteronel (TAK-700) TKI inhibitors Sunitinib Dasatinib Cabozantinib Endothelin receptor inhibitors Atrasentan x2 Zibotentan x3 Angiogenesis inhibitors Bevacizumab Lenalidomide Aflibercept Tasquinimod Microtubule inhibitors Cabazitaxel Radiotherapy Radium 223?? Immunotherapy Sipuleucel T Ipilumimab Prostvac

14 Summary of clinical trial outcome Patient setting Control Increase in median, months OS HR p value Docetaxel/P 1 First-line Mitoxantrone/P Cabazitaxel/P 2 Post-docetaxel Mitoxantrone/P < Abiraterone/P 3 Post-docetaxel Placebo/P < Abiraterone/P 4 Chemo-naïve Placebo/P * Enzalutamide 5 Post-docetaxel Placebo <0.001 Enzalutamide 6 Chemo-naïve Placebo < Radium Bone metastases, Pre- and post docetaxel Placebo <0.001 *OS did not reach the prespecified efficacy boundary (p=0.0035) 1. Berthold DR, et al. J Clin Oncol 2008;26:242 5; 2. de Bono JS, et al. Lancet 2010;76: ; 3. Fizazi K, et al. Lancet Oncol 2012;13:983 92; 4. Rathkopf DE, et al. J Clin Oncol 2013;31(suppl. 6): abstract 5; 5. Scher HI, et al. N Engl J Med 2012;367: ; Beer et al., J Clin Oncol 32, 2014 (suppl 4; abstr LBA1^); 7. Parker C, et al. N Engl J Med 2013;369: These studies are different (in type, population, inclusion/exclusion criteria, design and method, primary objectives) and therefore a comparison cannot be made.

15 Molecular Components of the AR The AR is composed of 3 major functional domains: N-terminal domain (NTD) Responsible for the majority of transcription activity DNA-binding domain (DBD) Contains 2 zinc finger motifs that facilitate DNA binding Ligand-binding domain (LBD) Mediates ligand binding Chromosome Gene mrna Protein 5 1 Xp q11.2 Xq ATG NTD 180kb TGA DBD LBD NLS Hu R, et al, Expert Rev Endocrinol Metab, 2010;5(5): , 2010, Informa Healthcare. Reproduced with permission of Informa Healthcare. 8 NLS, NUCLEAR LOCALIZATION SIGNAL. HU R, ET AL. EXPERT REV ENDOCRINOL METAB. 2010;5(5):

The Development of mcrpc Involves Alterations in AR-Signaling Androgen Signaling 1

small-cell carcinomas often lack AR expression 2,3 1. HARRIS WP, ET AL.

2004;351(15):1488-1490. 3. APARICIO A, TZELEPI V. ONCOLOGY (WILLISTON PARK).

16 The Development of mcrpc Involves Alterations in AR-Signaling Androgen Signaling 1 Pathways to Castration Resistance 1 Aggressive forms of CRPC, such as neuroendocrine, and small-cell carcinomas often lack AR expression 2,3 1. HARRIS WP, ET AL. NAT CLIN PRACT UROL. 2009;6(2): DEBES JD, TINDALL DJ. N ENGL J MED. 2004;351(15): APARICIO A, TZELEPI V. ONCOLOGY (WILLISTON PARK). 2014;28(10): Reprinted by permission from Macmillan Publishers Ltd: Nat Clin Pract Urol, Harris WP, et al. 2009;6(2):

17 Target 1: Gonadal/Circulating T LHRH Leuprolide Goserelin Degarelix others Estrogens TESTOSTERONE SHBG GTX758 (ERa agonist) SHBG Free T Modified from Peter Nelson, MD

Target 2: Adrenal/Intracrine Ligands AKR1C3

VT-464 AKR1C3 ü Indomethacin ü I-analogs 3bHSD

18 Target 2: Adrenal/Intracrine Ligands AKR1C3 CYP17 DHEA A-dione ADRENAL T DHT Cholesterol -- AKR1C3 CYP17 -- de novo CYP17 ü Ketoconazole ü Abiraterone ü TAK700 ü TOK001 ü VT-464 AKR1C3 ü Indomethacin ü I-analogs 3bHSD ü Abiraterone-HD ü Trilostane Modified from Peter Nelson, MD

19 Target 3: AR Degradation Modified from Peter Nelson, MD HSP90 Antagonists ü 17AAG ü STA9090 ü AT13387 ü Others Selective AR downregulators or degraders* ü Curcumin ü TOK001 ü AZD3514 ü ASC-J9 ü PPD ü Antisense *many others with low potency HSP90 HSP90 AR AR X PROTEASOME

20 Target 4: Androgen Receptor Blockade T 5aReductase DHT Modified from Peter Nelson, MD P AR P AR Ligand Binding AR ü enhanced degradation ü translocation block ü unproductive transcription Competitive Antagonists Flutamide Bicalutamide Nilutamide Enzalutamide ARN509 TOK001

21 Target 5: Prevent AR Nuclear Translocation Microtubule Inhibitors ü Enzalutamide ü Paclitaxel ü Docetaxel ü Cabazitaxel Nuclear Translocation P AR P ARsv P AR P AR Modified from:peter Nelson, MD

22 Target 6: Interfere With AR Enablers P AR P Signaling Pathways ü Her2/3 ü IGF1R ü CDKs ü others Nuclear Translocation ARsv P AR P AR Modified from:peter Nelson, MD

23 Target 7: Block AR DNA/Co-Activator Interaction P AR P AR Androgen-response Elements (ARE) Coactivators TM Important as they may target ARsv Target Gene Expression Non-Competitive Antagonists* EPI-001 D2 Pyrivinium Harmol HCL Others Modified from Peter Nelson, MD *N-C interactions Nuclear translocations AR AF2-LXXLL Interactions Co-factor inhibition

24 Target 8: AR Downstream Effectors PI3K-Pathway Inhibitors P AR P AR TM Target Gene Expression ETS-family Inhibitors Proliferation Survival Metabolism CAMKK2 inhibitor (STO-609) Modified from Peter Nelson, MD

29 AR Splice Variants Guo Z and Qiu Y. Int J Biol Sci. 2011;7:

30 AR splice variants are associated with poor prognosis and Treatment resistance The translation of splice variants results in proteins with altered activity and regulation 1 AR Splice Variants Exons 4-8 of AR are not required for transcriptional activity and splice variants lacking this region may be constitutively active 2 In one study, expression of AR variants lacking the ligand-binding domain in CRPC bone metastases was associated with poor prognosis 2 Detection of AR-V7 in tumor cells is associated with treatment resistance 3,4 Full-length AR Ligand-binding domain Amino acid AR-V Thadani-Mulero M, et al. Cancer Res. 2014;74(8): American Association for Cancer Research

31 Lack of Response Associated with AR-V7 (Johns Hopkins University) Prospective study of M1 CRPC patients eligible for abiraterone (N=31) and enzalutamide (N=31) treatment; AR-V7 identified in CTC samples pretreatment None (0/18) of the AR-V7 positive patients achieved a PSA50 Only 1 AR-V7 positive patient showed any PSA reduction (enzalutamide) AR-V7 prevalence increased post additional treatments Response Treatment 1 Baseline AR-V7+ Abiraterone 19% (N=31) (6/31) Enzalutamide (N=31) 39% (12/31) AR-V7 status PSA50 P- value rpfs P- value OS (95% CI) P value + 0% (0/6) 2.3 mos 10.6 mos (8.5 NR).004 < % (17/25) >6.3 mos >11.9 mos (11.9 NR) + 0% (0/12) 2.1 mos 5.5 mos (3.9 NR).004 < % (10/19) 6.1 mos NR (NR NR) Patient Treatment Status 2 Before enzalutamide or abiraterone Post enzalutamide Post abiraterone Post abiraterone & enzalutamide AR-V7 Prevalence 12% 25% 51% 67% CRPC=castration-resistant prostate cancer; CTC=circulating tumor cell; M1=metastatic disease; NR=not reached; OS=overall survival; PSA=prostate specific antigen; rpfs=radiographic progression-free survival. 1. Antonarakis ES et al. NEJM /NEJMoa Antonarakis ES et al. ASCO

32 32 Antonarakis et al NEJM 2014

33 33 Antonarakis et al NEJM 2014

35 Mutation in 3BHSD1 Facilitates Conversion of Precursors to DHT

Glucocorticoid Receptor Activation Post-Enzalutamide Treatment Acquired resistance to enzalutamide can be associated with increased expression of the glucocorticoid receptor (GR) Baseline Marrow

37 Glucocorticoid Receptor Activation Post-Enzalutamide Treatment Acquired resistance to enzalutamide can be associated with increased expression of the glucocorticoid receptor (GR) Baseline Marrow biopsy Enz 8 weeks Marrow biopsy Enz Continue until no clinical benefit >6 months <6 months Good responder Poor responder PSA decline Good Poor >50% 11 1 <50% 2 13 Arora VK, et al. Cell.2013;155:

39 D. Lorente, J.S. De Bono, Eur J Cancer 2014;50:753 Sequence or Layering?

40 FUTURE Novel and Multi Modal Therapy Radium-223 Saad et al., Urol Oncol. 2014;32(2):70-9.

42 Conclusions The AR continues to be a major driver in the growth and survival of prostate CA cells, even in the CRPC patient As urologists, we need to understand the nuances of resistance mechanisms and genomic alterations Despite all the recent advances, there remains multiple challenges and opportunities for researchers to better understand the disease and possible development of novel targeted agents

Targeting the Androgen Receptor in Prostate Cancer. Raoul S. Concepcion, MD,FACS FDUS/Colorado Springs August 2017

Targeting the Androgen Receptor in Prostate Cancer Raoul S. Concepcion, MD,FACS FDUS/Colorado Springs August 2017 Consultant: GHI, CUSP, Tolmar, Integra Connect, Cellay, AZ Speakers Bureau: Dendreon, Astellas,