Agents in the Treatment of ER+ Aromatase Inbitor-Resistant Metastatic Breast Cancer: M-THOR Inhibitors

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1 Agents in the Treatment of ER+ Aromatase Inbitor-Resistant Metastatic Breast Cancer: M-THOR Inhibitors Valero, M.D., Professor of Medicine and Deputy Chairman Department of Breast Medical Oncology The University ot Texas MD Anderson Cancer Center Houston, Texas

2 Caso clínico Paciente de 63 años sin antecedentes patológicos de interes. Fumadora de 2 cig/día Abril de 21. Se diagnostica un carcinoma ductal infiltrante de CSE mama derecha, grado II, RE 1%, RP 9%, HER2-. Se realiza tumerectomía+ BSGC seguida de vaciamiento axilar AP. Carcinoma ductal infiltrante de 2,6 cm. de diámetro y afectación de 2/15 ganglios axilares disecados. Quimioterapia adyuvante con antraciclinas y taxanos, RT. Locorreegional y letrozol adyuvante. Junio de 213 la paciente comienza a presentar dolor lumbar de características mecánicas. Octubre de 213 se diagnostican metástasis ganglionares a nivel de FSCD, metástasis liticoblásticas a nivel de pelvis y columna lumbar y 2 nodulos en pulmón izquierdo de 2 cm. De diametro máximo. ECOG 1 Se biopsia la FSCD. AP. Carcinoma ductal infiltrante, grado II, RE 8%, RP 5%, HER2-

3 The Estrogen Receptor as a Target Current endocrine strategies limited by resistance In MBC: 3% to 5% initially respond; all eventually acquire resistance De Novo Resistance Lack of ER expression Alternative pathways driving cell Acquired Resistance ER expression and function ER loss (4% to 5% at time of progression on therapy) Role of GF receptors GF signaling (eg, levels of EGFR / HER2 or activation) Downstream intracellular signaling Normanno, et al. Endocrine-Related Cancer. 25;12: ; Johnston, et al. Cancer. 28:112:

4 Review of Trials of Hormone Therapy in Advanced Breast Cancer After Progression on Prior Non-Steroidal Aromatase Inhibitor

5 Timeline of Approval of New Agents for Hormone Receptor Positive MBC Tamoxifen (1977) Letrozole (1997) Fulvestrant (22) Toremifene (1997) Exemestane (1999) Everolimus (212) Anastrozole (1995) Drugs@FDA. Accessed May 24, 212

6 Selected Trials of Hormonal Therapy Including Everolimus After Progression on Prior AI* Trial EFECT Fulvestrant (25) vs exemestane CONFIRM Fulvestrant (5) vs fulvestrant (25) SoFEA Fulvestrant + anastrozole vs fulvestrant (25) vs exemestane TAMRAD Tamoxifen + everolimus BOLERO-2 Exemestane + everolimus N Fulvestrant 25 Fulvestrant 5 Everolimus Combinations *Non-steroidal aromatase inhibitor.

7 EFECT: Fulvestrant (25, loading) vs Exemestane N = 693 PMW with advanced HR+ BC after failure of NSAI therapy FULVESTRANT 5 mg IM day 1, 25 mg day 14, 28, monthly EXEMESTANE 25 mg QD Primary TTP Secondary ORR, CBR, DOR, TTR, OS, tolerability FUL n = 351 EXE n = 342 P-value TTP (mo) ORR (%) Fulvestrant (25 loading) similar to exemestane Chia S, et al. J Clin Oncol 28;26(1):

8 CONFIRM: Fulvestrant 25 vs 5 mg N = 736 PMW with advanced HR+ BC after failure of prior endocrine therapy FULVESTRANT 5 mg IM on day 1, 14, 28, monthly FULVESTERANT 25 mg IM monthly Primary PFS Secondary ORR, CBR, DoCB, OS, Qol FUL 5 n = 362 FUL 25 n = 374 P-value PFS (mo) ORR (%) CBR (%) Bachelot T, et al. J Clin Oncol 212. Epub 1-7; DiLeo et al. J Clin Oncol 21;28:

9 SoFEA: Fulvestrant (25, loading) With or Without Anastrozole vs Exemestane N = 723 Post menopausal women with advanced HR+ BC following progression on NSAI FULVESTRANT 5 mg loading dose on day 1, then 25 mg monthly + ANASTROZOLE 1 mg/daily FULVESTRANT 5 mg loading dose on day 1, then 25 mg monthly + Placebo daily EXEMESTANE 25 mg/daily Primary PFS Secondary ORR, CBR, OS, tolerability No significant differences were observed in PFS, ORR, CBR, or OS FUL 5 n = 231 FUL + ANA n = 243 EXE PFS (mo) Johnston S et al. EBCC

10 Strategies to Overcome Resistance in HR+ Breast Cancer IGFR-1 HER2-1 Plasma membrane P P P P Estrogen PI3-K P P SOS RAS RAF ER mtor Akt P P MAPK MEK P P Cytoplasm P P P ER P ER p16 CBP Basal transcription machinery Nucleus ERE ER target gene transcription DiCosimo & Baselga. Nature Clin Prac Oncol. 29.

11 TAMRAD Schema Randomized Phase II (n=111) Metastatic patients with prior exposure to AI Randomization A : Tamoxifen, 2 mg/d (TAM) B : Tamoxifen 2 mg/d + RAD1 1 mg/d (TAM + RAD) Stratification: Primary or secondary hormone resistance Primary: Relapse during adjuvant AI; progression within 6 months of starting AI treatment in metastatic setting Secondary: Late relapse ( 6 months) or prior response and subsequent progression to metastatic AI treatment No crossover planned Primary end point: CBR (CR+ PR+ SD for 6 months) Bachelot T, et al. J Clin Oncol 212. Epub 1-7

12 TAMRAD: CBR at 6 months Tamoxifen + RAD1 Tamoxifen Bachelot T, et al. J Clin Oncol 212. Epub 1-7

13 Probability of Survival Probability of Survival Time to Progression Overall Survival TAM: 4.5 mo. TAM + RAD: 8.6 mo. 1. HR =.54; 95% CI ( ) Exploratory log-rank: P =.26 HR =.45; 95% CI ( ) Exploratory log-rank: P =.19.9 TAM.8 TAM + RAD Month 1..9 TAM.8 TAM + RAD Month Patients at risk TAM + RAD: n = TAM : n = Patients at risk TAM + RAD: n = TAM : n = Bachelot T, et al. J Clin Oncol 212. Epub 1-7

14 BOLERO-2 Schema N = 724 Postmenopausal ER+ HER2- MBC Recurrence or progression to letrozole or anastrozole 2 1 2:1 Everolimus 1 mg/day + Exemestane 25 mg/day (N = 485) Placebo + Exemestane 25 mg/day (N = 239) PFS OS ORR Bone Markers Safety QOL PK Stratification: 1. Sensitivity to prior hormonal therapy 2. Presence of visceral disease No cross-over Baselga et al. ESMO 211; Hortobagyi G et al. SABCS 211, Baselga et al NEJM 212.

15 BOLERO-2: Overall Response Rate and Clinical Benefit Rate by Local Assessment Everolimus + Exemestane Placebo + Exemestane 33.4% P < P <.1 9.5%.4% Response 18.% Clinical Benefit Baselga J, et al. N Engl J Med 212;366(6):52-9.

16 Probability (%) of Event BOLERO -2: Primary Endpoint, PFS (18-Month Follow-up, Central) HR=.38 (95% CI: ) Log-rank P value: <.1 Kaplan-Meier medians EVE 1 mg + EXE: 11.1 months PBO + EXE: 4.14 months 4 2 EVE 1 mg + EXE (n/n=188/485) PBO + EXE (n/n=132/239) Number of patients still at risk Time (week) EVE 1 mg + EXE PBO + EXE Piccart ASCO abstract 551.

17 BOLERO-2 PFS in Subgroups Favors Everolimus + Exemestane Favors Placebo + Exemestane Subgroups (N) All (724) Age <65 (449) 65 (275) Hormonal sensitivity YES (61) NO (114) Visceral metastasis YES (46) NO (318) Baseline ECOG PS (435) 1, 2 (274) Prior chemotherapy YES (493) NO (231) No. of prior therapies 1 (118) 2 (217) 3 (389) Non-NSAI hormonal therapy YES (398) NO (326) PgR status positive YES (523) NO (184) Hazard Ratio Baselga et al. N Engl J Med 212

18 BOLERO-2: Most Common G3/4 AEs Everolimus + Exemestane (N = 482), % Placebo + Exemestane (N = 238), % All Grades Grade 3 Grade 4 All Grades Grade 3 Grade 4 Stomatitis Fatigue 33 3 < Dyspnea <1 Anemia 16 5 <1 4 <1 <1 Hyperglycemia 13 4 <1 2 <1 AST 13 3 <1 6 1 Pneumonitis 12 3 Baselga J, et al. N Engl J Med 212;366(6):52-9.

19 BOLERO-2: HRQoL in Patients With HR+ ABC (18-Month Follow-Up) Although the combination of EVE + EXE resulted in higher rates of grade 3/4 toxicity compared with PBO + EXE, analyses consistently show that time to definitive deterioration in EORTC QLQ-C3 GHS was longer in EVE + EXE combination versus EXE monotherapy Time to definitive deterioration for EORTC QLQ-3 GHS, MID = 5% EORTC QLQ-C3 GHS EVE + EXE PBO + EXE TTD, months; MID = 5% Decrease from baseline % CI P value (2-sided).84 TTD, months; MID = 1 points decrease % CI P value (2-sided).117 HRQoL, health-related quality of life; EORTC QLQ-C3 GHS, European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 3 Global Health Scale; MID, minimal important difference; TTD, Time to definitive deterioration Beck JT, et al. ASCO; 212. Abstract

20 BOLERO-2 (39-mo): Final OS Analysis Presented at EBCC-9; March 214; Glasgow, Scotland. Abstract 1LBA. HR =.89 (95% CI, ) Log-rank P =.14 Kaplan-Meier medians EVE+EXE: 3.98 months PBO+EXE: months Censoring times No. at risk EVE+EXE PBO+EXE At 39 months median follow-up, 41 deaths had occurred (data cutoff date: 3 October 213) 267 deaths (55%) in the EVE+EXE arm vs 143 deaths (6%) in the PBO+EXE arm One-sided P value was obtained from the log-rank test stratified by sensitivity to prior hormonal therapy and presence of visceral metastasis from IXRS. Abbreviations: CI, confidence interval; EVE, everolimus; EXE, exemestane; HR, hazard ratio; IXRS, Interactive Voice and Web Response System; PBO, placebo. 2

21 BOLERO-2: Conclusions Adding everolimus to endocrine therapy improved response rate and PFS (4.6-month benefit; P <.1) in patients with HR +, HER2 advanced BC that progressed after previous NSAI therapy Adding everolimus to endocrine therapy did not statistically improve overall survival in second and third line therapy(31. months EVE+EXE vs 26.6 months PBO+EXE; HR =.89; 95% CI, ; P =.14) Everolimus adds some toxicity to endocrine therapy, mainly stomatitis, fatigue, rash and diarrhea Ongoing translational research should further refine the benefit of mtor inhibition and related pathways in this treatment setting 21

22 MDACC Guidelines 215 Post-menopausal Prior Tamoxifen Prior Aromatase Inhibitor No Prior Tamoxifen or AI Aromatase Inhibitor Exemestane + Everolimus or Fulvestrant Exemestane + Everolimus or Fulvestrant Exemestane + Everolimus or Fulvestrant Exemestane + Everolimus or Fulvestrant Tamoxifen Anastrozole + Fulvestrant Exemestane + Everolimus Tamoxifen Androgen, Megestrol/Highdose Estrogen