Targeting HER family receptors in breast cancer Prof. Sabino De Placido Dip. di Endocrinologia ed Oncologia Molecolare e Clinica Università Federico II --- Napoli, Italia

Targeting HER2: Key points HER2 gene amplification and/or overexpression occurs in about 20% of breast cancers and is associated with more-aggressive disease and, until the advent of HER2-targeted agents, a worse outcome The monoclonal antibody, trastuzumab (which targets HER2), and the small molecule tyrosine kinase inhibitor, lapatinib (which targets HER1 and HER2), have considerable efficacy in HER2-positive breast cancer

Adjuvant Setting What we know Trastuzumab has changed the natural history of early HER2+ BC Year

Adjuvant Trastuzumab predicted to prevent recurrence in almost 28,000 patients over a 10-year period in the 5 major EU countries No. of patients prevented from developing metastases Patients, n 20,000 Incidence of MBC without Herceptin Herceptin introduced 18,000 27,737 16,000 14,000 12,000 10,000 8000 6000 4000 2000 2000 2005 2010 2015 Year Weisgerber-Kriegl et al, ASCO 2008 4

More than 14.000 patients were recruited in 4 international clinical trials HERA (ex-USA) BCIRG 006 (global) Observation IHC / FISH (n=5,090) FISH (n=3,222) 1 year 1 year 2 years 1 year NCCTG N9831 (USA) NSABP B-31 (USA) IHC / FISH (n=3,505) IHC / FISH (n=2,030) 1 year 1 year 1 year Doxorubicin + cyclophosphamide Docetaxel + carboplatin Standard CTx Docetaxel Trastuzumab Paclitaxel IHC, immunohistochemistry FISH, fluorescence in situ hybridisation CTx, chemotherapy Piccart-Gebhart et al 2005 Romond et al 2005; Slamon et al 2006

Neoadjuvant setting What we know

Adjuvant setting What we do not know Small, node negative tumors are under represented in clinical trials

Studies investigating clinical outcome of pT1pN0 tumors by HER-2 and hormone receptors (HRs) status. Results Overall 7,164 pts. with pT1pN0 tumors median follow-up 4.5 - 12.4 yrs.) 600 pts. with HER-2 + tumors % HER-2 + disease ranging between 7 and 10% Absolute risks of distant relapse HER2+ 5 yrs. ± 10-15% 10 yrs. 22-28% Increased risk of disease relapse if HER-2 + hazard ratios ranging between 2.4 and 8.99 Reviewed by Oakman C et al, Educational book – ESMO meeting, Milan – October 2010

Caveats “Take-home” messages - heterogeneity in adjuvant therapies Studies investigating clinical outcome of pT1pN0 tumors by HER-2 and hormone receptors (HRs) status. Caveats and Conclusions Caveats - heterogeneity in adjuvant therapies - HRs status not always centrally revised - in 3 out of 7 studies pT1c tumors were eligible - only 2 out of 7 studies evaluate outcome by combination of HER-2 and HRs status “Take-home” messages - there is a substantial degree of concordance in considering HER-2 + patients with pT1pN0 tumors at increased risk of relapse compared to the HER-2 negative population (2 to 9 fold increase) Reviewed by Oakman C et al, Educational book – ESMO meeting, Milan – October 2010

Key question Is proportional benefit from adjuvant systemic therapies dependent on disease stage ?

Potential options for adjuvant treatment of endocrine-resistant pT1b pN0 tumors HER-2 + Docetaxel-Cyclophosphamide (TC) x 4 + Trastuzumab* (lack of phase III data) Docetaxel-Carboplatin-Trastuzumab (TCH) x 6 (BCIRG 006 data) Trastuzumab Trastuzumab * concomitant trastuzumab > sequential trastuzumab

Treatment decision: a multi-factorial process Tumor* : Size Vascular invasion Ki-67 Patient : Co-morbidities Age Patient : Expectations Preferences Treatment decision

Adjuvant setting What we do not know Duration of Trastuzumab

Adjuvant trials with different duration of trastuzumab administration HERA (PI M. Piccart): sample size ~34001 12 vs 24 months of H following adjuvant CT Phare (PI X. Pivot): sample size ~34002 6 vs 12 months of H following adjuvant CT Persephone (UK-NCRI): sample size ~40003 Hellenic Oncology Group (Greece): sample size 4784 6 vs 12 months of H with ddDoc after FEC SOLD (PI H. Joensuu): sample size ~30006 HD 3-wkly x3 ->FE75C x3 vs HD 3-wkly x3 ->FE75C x3 -> H 3-wkly x14 ShortHER (PI PF. Conte): sample size ~12505 D 3-wkly x3 + H weekly x 9 -> FE60C x3 AC or EC x 4 -> HD or HP 3-wkly x4 -> H 3-wkly x14

Metastatic Disease

Overall Survival by Trastuzumab Treatment Groups 1.0 0.0 Overall Survival Probability Months from Diagnosi 0.6 0.4 60 0.2 0.8 12 24 48 36 Negative No Trastuzumab Trastuzumab HER2+ / Herceptin HER2+ / No Herceptin HER2-

What we Know The first line

HERNATA Study

HERNATA study : results Time to Progression Overall Survival Andersson JCO 2010

HERNATA study: results Time to Treatment Failure Andersson JCO 2010

HERNATA study : safety profile In summary, the results from this randomized phase III trial of first-line therapy in HER2-positive MBC or LABC failed to demonstrate superiority in terms of efficacy of docetaxel plus trastuzumab compared with vinorelbine plus trastuzumab. However, toxicity was much more pronounced with docetaxel, and thus vinorelbine plus trastuzumab should be considered as an alternative first-line option with a favorable risk/benefit balance Andersson JCO 2010

What we Know The second line

Cumulative progression-free (%) Tyverb plus capecitabine: significantly longer TTP in difficult to treat population (EGF100151, independent assessment) Tyverb + capecitabine Capecitabine HR: 0.57 (95% CI: 0.43, 0.77) p=0.00013 Cumulative progression-free (%) 18.6 wks (4.3 mos) 27.1 wks (6.2 mos) 1. Cameron et al. Breast Cancer Res Treat 2008;[Epub ahead of print]. Figure Adapted from Cameron D, Casey M, Press M et al. A phase III randomized comparison of lapatinib plus capecitabine versus capecitabine alone in women with advanced breast cancer that has progressed on trastuzumab: updated efficacy and biomarker analyses. Breast Cancer Res Treat, 2008 Epub ahead of print, with kind permission of Springer Science and Business Media.

What we Know Beyond the second line

Cumulative progression-free (%) Time from randomisation (weeks) Lapatinib in combination with trastuzumab significantly prolonged PFS compared with lapatinib alone (EGF104900) Subjects at risk: 148 Lapatinib Lapatinib + trastuzumab 53 73 21 42 13 27 5 8 2 6-month PFS Cumulative progression-free (%) 13% 28% 20 40 60 80 100 10 30 50 Time from randomisation (weeks) Lapatinib Lapatinib + trastuzumab n=145 n=146 Progressed or died, n 128 127 Median, wks 8.1 12.0 HR (95% CI) 0.73 (0.57, 0.93) p value 0.008

Updated overall survival in ITT (EGF104900) 100 L n=145 L+T n=146 Died, n (%) 113 (78) 105 (72) Median, months 9.5 14 Hazard ratio (95% CI) 0.74 (0.57, 0.97) Log-rank p value .026 80% 80 70% 60 Cumulative % alive without progression 56% 6 month OS 40 41% 20 L+T L 12 month OS 5 10 15 20 25 30 35 Patients at risk Time from randomization (months) L L+T 148 121 102 88 65 64 47 43 28 25 13 1

Lapatinib effect on ErbB2 accumulation at cell membrane: novel mechanism for enhanced effects of combined anti-ErbB2 therapy Lapatinib has been shown to enhance antitumour effect of trastuzumab in vitro and in clinical studies This study explored the mechanism for this effect by investigating impact of lapatinib and trastuzumab on receptor expression and signalling Treatment: lapatinib, trastuzumab, or both ErbB2-positive BC cells (SKBR3 and MCF7-HER2) In vitro assays: Receptor expression, phosphorylation, signalling, tumour growth Mouse xenograft Scaltriti et al., J Clin Oncol ASCO Annual Meeting Proceedings 2008; 26(Suppl.): Abstract 3594 and poster Scaltriti et al., Oncogene 2009; www.nature.com/onco 29

What we Know HER2+ and HR+

HER2 and hormone receptor-positive BC Clinical trials to assess therapy Cortes Nat Rev Clin Oncol 2010

Overall response rates (%) HER2 and hormone receptor-positive BC Clinical trials to assess therapy 100 80 60 40 20 Combination with chemotherapy H0648g M77001 Overall response rates (%) Combination with Aromatase inhibitors EGF30008 TAnDEM Trastuzumab + anastrozole Lapatinib + letrozole Trastuzumab + paclitaxel Trastuzumab + docetaxel Drug regimen Figure 1: Overall response rates in HER2-positive and hormone receptor-positive metastatic breast cancer. Anti-HER2 therapy was combined either with chemotherapy or aromatase inhibitors in four pivotal trials. The combination with chemotherapy showed higher overall response rates. 8.10-12 Cortes Nat Rev Clin Oncol 2010

What else we Know The Future Trastuzumab + Pertuzumab

Pertuzumab and trastuzumab have complementary mechanisms of action HER2 HER1/3/4 Trastuzumab Dimerization domain Subdomain IV Trastuzumab: Inhibits ligand-independent HER2 signaling Activates ADCC Prevents HER2 ECD shedding Pertuzumab: Inhibits ligand-dependent HER2 dimerization and signaling Activates ADCC ADCC, antibody-dependent cell-mediated cytotoxicity; ECD, extracellular domain

Pertuzumab + trastuzumab CLEOPATRA: a Phase III trial of trastuzumab + pertuzumab in the 1st-line setting Placebo + trastuzumab PD n=406 Docetaxel* ≥6 cycles recommended Patients with HER2-positive MBC centrally confirmed (N = 808) 1:1 Pertuzumab + trastuzumab PD n=402 Docetaxel* ≥6 cycles recommended Randomization was stratified by geographic region and prior treatment status (neo/adjuvant chemotherapy received or not) Study dosing q3w: − Pertuzumab/Placebo: 840 mg loading dose, 420 mg maintenance − Trastuzumab: 8 mg/kg loading dose, 6 mg/kg maintenance − Docetaxel: 75 mg/m2, escalating to 100 mg/m2 if tolerated * <6 cycles allowed for unacceptable toxicity or PD; >6 cycles allowed at investigator discretion MBC, metastatic breast cancer; PD, progressive disease

Primary endpoint: Independently assessed PFS n = 433 PFS events 10 20 30 40 50 60 70 80 90 100 Ptz + T + D: median 18.5 months ∆ = 6.1 months Pla + T + D: median 12.4 months Progression-free survival (%) HR = 0.62 95% CI 0.51‒0.75 p<0.0001 5 10 15 20 25 30 35 40 Time (months) n at risk Ptz + T + D 402 345 267 139 83 32 10 Pla + T + D 406 311 209 93 42 17 7 Stratified by prior treatment status and region D, docetaxel; PFS, progression-free survival; Pla, placebo; Ptz, pertuzumab; T, trastuzumab

Overall survival: Predefined interim analysis Median follow-up: 19 Overall survival: Predefined interim analysis Median follow-up: 19.3 months, n = 165 OS events 100 90 80 70 HR = 0.64* 95% CI 0.47‒0.88 p = 0.0053* 60 Overall survival (%) 50 40 30 Ptz + T + D: 69 events 20 Pla + T + D: 96 events 10 5 10 15 20 25 30 35 40 45 Time (months) n at risk Pertuzumab + T + D 402 387 367 251 161 87 31 4 Placebo + T + D 406 383 347 228 143 67 24 2 * The interim OS analysis did not cross the pre-specified O’Brien-Fleming stopping boundary (HR ≤0.603; p ≤0.0012) D, docetaxel; OS, overall survival; Pla, placebo; Ptz, pertuzumab; T, trastuzumab

Cardiac tolerability Placebo + trastuzumab + docetaxel (n = 397) Pertuzumab + trastuzumab + docetaxel (n = 407) Investigator-assessed symptomatic LVSD* 1.8% 1.0% Independently adjudicated symptomatic LVSD* Fall in LVEF to <50% and by ≥10 percentage points from baseline 6.6% 3.8% * LVSD was defined as NYHA class III/IV LVEF, left ventricular ejection fraction; LVSD, left ventricular systolic dysfunction

Adverse events (all grades) ≥25% incidence or ≥5% difference between arms Adverse event, n (%) Placebo + trastuzumab + docetaxel (n = 397) Pertuzumab + trastuzumab + docetaxel (n = 407) Diarrhea 184 (46.3) 272 (66.8) Alopecia 240 (60.5) 248 (60.9) Neutropenia 197 (49.6) 215 (52.8) Nausea 165 (41.6) 172 (42.3) Fatigue 146 (36.8) 153 (37.6) Rash 96 (24.2) 137 (33.7) Decreased appetite 105 (26.4) 119 (29.2) Mucosal inflammation 79 (19.9) 113 (27.8) Asthenia 120 (30.2) 106 (26.0) Peripheral edema 119 (30.0) 94 (23.1) Constipation 99 (24.9) 61 (15.0) Febrile neutropenia 30 (7.6) 56 (13.8) Dry skin 17 (4.3) 43 (10.6)

Summary and conclusions CLEOPATRA met its primary endpoint and demonstrated a statistically significant and clinically meaningful improvement in PFS (HR = 0.62) in patients with HER2-positive MBC Median PFS increased by 6.1 months from 12.4 to 18.5 months The PFS improvement was consistent across subgroups and supported by the secondary endpoints of ORR and OS (immature) The combination of pertuzumab and trastuzumab plus docetaxel increased rates of diarrhea, rash, mucosal inflammation, febrile neutropenia, and dry skin These adverse events were primarily grades 1‒2, manageable, and occurred during docetaxel therapy There was no increase in cardiac adverse events or LVSD This new regimen may be practice-changing in HER2-positive first-line MBC

What else we Know The Future T-DM1

Trastuzumab emtansine (T-DM1): the first-in-class HER2-targeted antibody-drug conjugate Monoclonal antibody: trastuzumab Target expression: HER2 Highly potent chemotherapy (maytansine derivative) Cytotoxic agent: DM1 Systemically stable Breaks down in target cancer cell Linker T-DM1

HER2-positive, recurrent locally advanced breast cancer or MBC (N=137) Study Design TDM4450g: ongoing Phase II study of T-DM1 vs trastuzumab + docetaxel in first-line HER2-positive MBC Trastuzumab 8 mg/kg loading dose; 6 mg/kg q3w IV + Docetaxel 75 or 100 mg/m2 q3w (n=70) Crossover to T-DM1 (optional) PDa HER2-positive, recurrent locally advanced breast cancer or MBC (N=137) 1:1 T-DM1 3.6 mg/kg q3w IV (n=67) PDa Randomized, phase II, international, open-label studyb Stratification factors: World region, prior adjuvant trastuzumab therapy, disease-free interval Primary end points: PFS by investigator assessment, and safety Data analyses were based on clinical data cut of Nov 15, 2010 prior to T-DM1 crossover Key secondary end points: OS, ORR, DOR, CBR, and QOL aPatients were treated until PD or unacceptable toxicity. bThis was a hypothesis generating study; the final PFS analysis was to take place after 72 events had occurred.

Progression-Free Survival by Investigator Randomized Patients Median PFS, mos Hazard ratio 95% CI Log-rank P value 9.2 14.2 0.594 0.364– 0.968 0.0353 1.0 0.8 0.6 0.4 0.2 0.0 Trastuzumab + docetaxel (n=70) T-DM1 (n=67) Proportion progression-free 0 2 4 6 8 10 12 14 16 18 20 Time (months) Number of patients at risk T+D 70 66 63 53 43 27 12 4 2 2 0 T-DM1 67 60 51 46 42 35 22 15 6 3 0 Hazard ratio and log-rank P value were from stratified analysis.

Duration of Response by Investigator Patients with Measurable Disease at Baseline with an Objective Response Median DOR, mos 95% CI 9.5 NRa 6.6–10.6 – 1.0 0.8 0.6 0.4 0.2 0.0 Trastuzumab + docetaxel (n=40) T-DM1 (n=43) Proportion progression-free 0 2 4 6 8 10 12 14 16 18 Duration of objective response (months) Number of patients at risk T+D 40 40 38 32 19 8 2 1 1 0 T-DM1 43 41 38 33 27 19 12 6 3 0 Kaplan-Meier estimates are shown. aNR, not reached; longer follow-up is needed to estimate the duration of response in the T-DM1 arm.

Trastuzumab + docetaxel (n=66)c Incidence of Nonhematologic Adverse Events: ≥30% (All Grade) and/or ≥5% (Grade ≥3) of Patientsa AE All grade, n (%) Grade ≥3b, n (%) Trastuzumab + docetaxel (n=66)c T-DM1 (n=69)c,d Alopecia 44 (66.7) 3 (4.3) e Fatigue 30 (45.5) 34 (49.3) 3 (4.5) Nausea 29 (43.9) 33 (47.8) 2 (2.9) Diarrhea 11 (15.9) 2 (3.0) Peripheral edema 7 (10.1) Increased AST 4 (6.1) 27 (39.1) 6 (8.7) Pyrexia 15 (22.7) 1 (1.5) Headache 12 (18.2) 25 (36.2) Back pain 20 (30.3) 18 (26.1) 1 (1.4) Increased ALT 16 (23.2) Pneumonia 4 (5.8) Green represents those AEs with ≥20% difference between treatment arms. aIn either treatment arm. bNo adverse events listed were grade 5. cTwo patients mistakenly received a dose of T-DM1 and were thus included in the T-DM1 arm for safety analyses. dIncludes 3 patients who received at least 1 dose of trastuzumab alone or trastuzumab plus docetaxel. eNational Cancer Institute Common Terminology Criteria for Adverse Events v.3 only categorizes alopecia as grade 1 or grade 2; there is no grade ≥3 for this AE.

Trastuzumab + docetaxel Cardiac Safety Cardiac function was assessed locally and centrally based on cardiac ECHO/MUGA Prior anthracycline in the adjuvant setting was 44.8% and 48.6% in the T-DM1 and trastuzumab + docetaxel arms, respectively Asymptomatic LV dysfunction There were no clinically significant cardiac events reported LVEF assessment Trastuzumab + docetaxel T-DM1 Local assessment Patients assessed 65 67 Patients with post-baseline LVEF ≤40% 2a Central assessment 60 1b aBoth patients had prior anthracycline therapy in the adjuvant setting; 1 patient received prior trastuzumab therapy in the adjuvant setting. bThis patient did not receive prior treatment with an anthracycline.

Summary and Conclusions This is the first randomized study to evaluate an antibody-drug conjugate for HER2-positive MBC First-line treatment of HER2-positive MBC with T-DM1, compared with trastuzumab + docetaxel was associated with: A significant improvement in PFS (14.2 vs 9.2 mos; HR=0.594; P value=0.0353) Similar ORR but more durable responses (64.2%, median duration not reached vs. 58.0%, median duration 9.5 months) A lower rate of grade ≥3 AEs (46.4% vs 89.4%) These results validate the hypothesis that the unique properties of T-DM1 may lead to an improved therapeutic index Improved PFS with T-DM1 may result from improved tolerability/duration of treatment/response and intrinsic potency of HER2-targeted DM1 T-DM1 is being evaluated in phase III randomized clinical trials for HER2-positive MBC

TDM4370g (EMILIA) Phase III Study: T-DM1 vs Capecitabine + Lapatinib in HER2-Positive MBC T-DM1 (3.6 mg/kg) q3w HER2-positive LABC or MBC (N=980) Previously received trastuzumab-based therapy 1:1 Lapatinib (1250 mg/day, days 1–21) + capecitabine (1000 mg/m2, days 1–14) q3w Multicenter, randomized, open-label study Treatment continues until progressive disease/unacceptable toxicity Primary end points: PFS by IRF, OS, 1-y and 2-y survival rates, Safety Secondary end points: PFS by INV, ORR, CBR, DoR, QOL, TTF www.clinicaltrials.gov. NCT00829166.

MARIANNE: Primary efficacy objective: Primary safety objective: Trastuzumab + taxane (n=364) HER2-positive progressive or recurrent locally advanced BC or previously untreated MBC (n=1092) T-DM1 + pertuzumab (n=364) T-DM1 + placebo (n=364) Primary efficacy objective: PFS assessed by an independent review facility Primary safety objective: To compare the safety of T-DM1 + pertuzumab or T-DM1 + placebo vs trastuzumab + taxane BC = breast cancer; MBC = metastatic breast cancer; PFS = progression-free survival