Carlos L. Arteaga, M.D.Departments of Medicine and Cancer Biology

Breast Cancer Research ProgramVanderbilt Ingram Comprehensive Cancer Center

Vanderbilt University School of Medicine

Are We About To Cure HER2-Are We About To Cure HER2-Positive Breast Cancer?Positive Breast Cancer?

Slamon et al. Science 237:177, 1987

Median Survival

HER2 overexpression 3 yrsHER2 normal 6-7 yrs

HER2/Neu (ErbB2) oncogene is associatedwith poor prognosis in breast cancer

HER2 protein overexpression (IHC)

HER2 geneamplification (Southern)

HER2 (ErbB2) is Oncogenic

HER2Control

HER2

Soft Agar

ErbB4HER4

EGFR/ErbB1HER1

ErbB2HER2

ErbB3HER3

Lig

ands

EC

IC

Ligands and Receptors of the HER (ErbB) family

100

100

100

44

82

33

36

59

24

48

79

28

EGFTGF

AmphiregulinHB-EGF

BetacellulinEpiregulin

? Heregulin(Neuregulin)

HeregulinHB-EGF

BetacellulinEpiregulin

Ligand binding

Tyr-Kinase

C-terminus

Some facts about the HER2 receptor network and HER2+

breast cancer

• HER2 is the most potent kinase and HER2-HER3 the most potent signaling dimer of this receptor network

• The main survival program activated by the HER (ErbB) network is the PI-3 kinase/Akt pathway

• The antibody trastuzumab and the tyrosine kinase inhibitor lapatinib are approved by the FDA for the treatment of HER2+ breast cancer

EGF30001: Phase III trial of paclitaxel ± lapatinibin first line or metastatic breast cancer

No benefit from lapatinib when analyzing the whole cohort

Benefit from the addition of lapatinib to paclitaxelwas significant in patients with HER2+ cancers

Adjuvant trastuzumab prolongs survival ofpatients with HER2+ breast cancer

Romond, Perez, Bryant, et al. NEJM 2005

07442776612171672Trastuzumab05937468911621679Control0133801145523793351No. at risk

0

% S

urv

ivin

g d

isease-f

ree

1 2 3 4 50

50

60

70

80

90

100

Years after randomization

Trastuzumab(133 events)

p<0.0001HR=0.48

Control(261 events)

87.1%85.3%

67.1%

75.4%

70

10

20

30

40

50

60

70

80

90

0

100

* Censors 4 patients who died due to causes other than breast cancer

10

20

30

40

50

60

0

Time (weeks)

CapecitabineLapatinib +

Capecitabine

0.00016P-value (log-rank, 1-sided)

69 (43%)45 (28%)Progressed or died*19.736.9Median TTP, wks

161160No. of pts

0.51 (0.35, 0.74)

Hazard ratio (95% CI)

% p

ati

en

ts f

ree f

rom

pro

gre

ssio

n*

Lapatinib prolongs progression-free survivalafter trastuzumab (Geyer et al. NEJM 2006)

Processing of trastuzumab-DM1 conjugate

Derivative ofMaytansine

Trastuzumab

Linker: MCC

• Normal-tissue target expression

• Fc-mediated uptake

• Non-specific uptake

HER2

Target-dependent cytotoxic activity

Trastuzumab-DM1 but not trastuzumab induces apoptosisand cell lysis and works in trastuzumab-resistant tumors

Lewis Phillips et al. Cancer Res. 68:9280, 2008

Krop et al. SABCS 2009 (late breaking abstract 710)

• HER2+ disease by FISH or 3+ IHC by local lab• Measurable disease by CT scan as per RECIST• Prior anthracycline, trastuzumab, taxane,

capecitabine and lapatinib therapy in any setting• Prior treatment with two HER2-directed regimens in the

metastatic setting• Documented progression on their most recent treatment

regimen• No history of significant cardiac disease; left ventricular

ejection fraction (LVEF) ≥50%• No history of Grade ≥3 hypersensitivity to trastuzumab or

toxicity requiring discontinuation • No Grade ≥3 peripheral neuropathy• No untreated or symptomatic brain metastases, or any

treatment for brain metastases within 3 months of first dose

• HER2+ disease by FISH or 3+ IHC by local lab• Measurable disease by CT scan as per RECIST• Prior anthracycline, trastuzumab, taxane,

capecitabine and lapatinib therapy in any setting• Prior treatment with two HER2-directed regimens in the

metastatic setting• Documented progression on their most recent treatment

regimen• No history of significant cardiac disease; left ventricular

ejection fraction (LVEF) ≥50%• No history of Grade ≥3 hypersensitivity to trastuzumab or

toxicity requiring discontinuation • No Grade ≥3 peripheral neuropathy• No untreated or symptomatic brain metastases, or any

treatment for brain metastases within 3 months of first dose

Key eligibility criteria

Clinical activity of trastuzumab-DM1 (n=110)

Krop I et al. SABCS 2009 (late breaking abstract 710)

Tumour response IRF(n=110)

Investigator(n=110)

Objective response rate, %(95% CI)

32.7(24.1–42.1)

30.0(22.0–39.4)

CR 0 1.8

PR 32.7 28.2

SD* 46.4 52.7

PD 18.2 13.6

UE 1.8 0.9

Missing 0.9 2.7

Clinical benefit rate, %(95% CI)

44.5(35.1–54.3)

40.0(31.1–49.3)

IRF, independent review facilityObjective response – CR or PR determined by two consecutive tumour assessments at least 28 days apartClinical benefit – objective response or SD maintained for at least 6 months

IRF, independent review facilityObjective response – CR or PR determined by two consecutive tumour assessments at least 28 days apartClinical benefit – objective response or SD maintained for at least 6 months

Implications• Even in advanced stages, HER2+ tumors

remain HER2-dependent

• Single agent anti-HER2 therapies do not inhibit the HER2 network completely

• Combinations of HER2-targeted drugs early in the treatment of HER2+ breast cancers is the rational way to go

• The optimal combination(s) of anti-HER2 agents up front may abrogate acquired resistance, shorten the duration of therapy, and dispense the need of chemotherapy

BT474 HR5

25016010575

P-Tyr

HER3

p85

lapatinib

+ +

p85 i.p.

+ lapatinib

P-HER3

HER3

P-Akt

Akt

In order to induce an antitumor effect, anti-HER2therapies should inhibit the PI3K/Akt pathway

Akt

Yakes et al. Cancer Res. 62:4132, 2002; Junttila et al. Cancer Cell 15:429, 2009

Trastuzumab disrupts ligand-independent HER2/HER3/PI3K complexes

Contributed by Jenny Chang (Baylor), SABCS 2008

HER3 pre HER3 post

His

tosc

ore

0

50

100

150

200

250

300

Pre

-the

rapy

Pos

t-th

erap

y (2

wks

)

Inhibition of the HER2 with lapatinib is followed byupregulation of HER3 in primary HER2+ tumors

In collaboration with Jenny Chang (Baylor)

p=0.01

P-HER3 was also upregulated upon txNo change in S473 P-AktInhibition of P-HER2 was incompleteUnder review

lapatinib

BT474 SKBR3

HER3

SUM225

β-actin

0 1 4 13 24 48 h0 1 4 13 24 48 0 1 4 13 24 48

lapatinib: 0 1 4 13 24 48 h0 1 4 13 24 48

BT474

P-HER3 (Y1289) short

P-HER3 (Y1289) long

P-HER3 (Y1197)

P-HER3 (Y1222)

P-HER2 (Y1248)

HER2

EGFR

HER3

SKBR3

P-EGFR (Y1068)

Akt

S6

P-S6

P-Akt (S473)

P-Akt (T308)

P-Erk

Erk

β-actin

Upon inhibition of the HER2 kinase, HER2+ cells upregulate total and activated HER3

Garrett J, Arteaga CL. Unpublished

Met

PPI3K p110

p85

Akt

PI3K p110

p85

Akt

IGF-IR

IRS-1PPP

P

lapatinib

Activation of Compensatory Pathways

Is compensatory upregulation of HER3a possible mechanism of drug resistance?

P

EGFR

P

HER2 ErbB3

P

Tyrosine kinases that can activate HER3: MET, EGFR, FGFR2,

Src, IGF-IR (?), BRK (?)

Implication: Upregulation of HER3 provides a mechanismfor maintenance of PI3K and escape from drug action

HER3

P-HER3 (Y1289)

β-actin

0 1 4 13 24 48 0 1 4 13 24 48 hBEZ235

SKBR3BT474

Inhibition of either HER2 or PI3K/Akt results in upregulation

of HER3 RNA and protein and P-HER3

Active Akt mutant limits lapatinib-inducedupregulation of HER3 mRNA and protein

FOXO3a TO-PRO-3 Merge

2°

Ab

alo

ne

DM

SO

4 h

la

p1

h l

ap

C N C N C N

DMSO 13 h lap 24 h lap

FOXO3a

Upregulation of HER3 upon inhibition of HER2 blockadeis dependent on PI3 kinase and FoxO3a

HER3

β-actin

ctrl HER3 ctrl HER3 siRNA

BT474 SKBR3

DMSO 0.33 µM lap 1.0 µM lap

siC

TR

Lsi

HE

R3

dmso Lap 0.33 Lap 1.0

mea

n ar

ea o

f aci

ni (

% o

f con

trol

)

0.0

0.2

0.4

0.6

1.0

1.2

ctrl siRNAHER3 siRNA

*

**

p<0.05*

RNAi of HER3 enhances lapatinib action against HER2+ br ca cells

100

300

500

700

900

1100

1300

7 9 13 16 20 23 27 30 34 37

tum

or v

olu

me

(mm

3)

ctrl, n=9

lap, n=8

AMG-888, n=8

lap+AMG-888, n=9

*

#

**

#

**

##

**

##

**

* **

Neutralizing HER3 monoclonal antibody sensitizesBT-474 xenografts to lapatinib

days * p<0.05, ** p<0.01 versus control # p<0.05, ## p<0.01 versus lapatinib

Tx

p=.006

p=.00005

p=.034

p=.000007

p=.029

cont

rol

Pre-tx 2 weeksla

patin

ibla

p +

AMG

-888

Combination of lapatinib and AMG-888 inhibits FDG-PET

HE

R3

*

Fox

O3a

*

lap lap+AMG-888ctrl

P-A

kt

*

Biomarkers of combined HER2 and HER3 inhibition

Trastuzumab inhibits recovery of P-HER3 after lapatinib

P-HER3

lapatinib lap + trast

β-actin

0 1 4 13 24 48 1 4 13 24 48 h

BT

474

0 1 4 13 24 48 1 4 13 24 48 h

SK

BR

3 P-HER3

β-actin

Garret J, …….., Arteaga CL, Unpublished

Src, MET, FGFR2, IGF-IR,EGFR inhibitors and pertuzumabDid not block recovery of P-HER3

31

Phase III study to test if total HER2 blockade improves clinical outcome

RANDOMIZATION

Lapatinib 1000 mg/day PO Trastuzumab 4 2 mg/kg IV qw N=148

Lapatinib 1500 mg/day PO N=148

Stratification Factors

• Visceral Disease

• Hormone Receptor

Key Inclusion

• HER2+(FISH+/ IHC3+) MBC

• Progression on• Anthracycline

• Taxane

• Trastuzumab

• Progression on most recent trastuzumab regimen

Crossover if PD after 4wk therapy (N=73)

Study conducted and funded by GlaxoSmithKline

Lapatinib + trastuzumab improves OS compared to lapatinib in patients progressing on or after

trastuzumab

Blackwell KL, et al. J Clin Oncol 2010; 28;1124–1130

Neoadjuvant lapatinib randomized Phase III trial

neo-ALTTO (adjuvant lapatinib ± trastuzumab

treatment optimization) trial (n=450)

Summary• Current therapeutic inhibitors of HER2 do

not inhibit output to HER3 and PI3K/Akt completely

• Compensatory upregulation of HER3 function occurs by transcriptional and post-translational mechanisms

• To completely inhibit the HER2 network (and the PI3K pathway), compensatory upregulation of HER3 should be eliminated

• The best therapeutic strategy to eliminate HER3 function remains to be determined

Anti-HER3 (ErbB3) strategies in clinical development

• Human antibody (IgG1) AMG-888 (AMGEN-U3)

• Human antibody (IgG2) MM-121 (Merrimack-Sanofi)

• HER3 antisense EZN-3920 (Enzon Pharmaceuticals)

PI3K/AKT pathway inhibitors in clinical development

Hsp70Hip, etc

IP

Hsp90

IP

Hsp90

Release of the mature/refolded

protein

ATP

ATP

Protein

p23

p23

Protein

Protein

IP

17AAG

Ubiquination/degradation

p23

Hsp90

17-AAGProtein

Protein

Proteins degraded:EGFR/HER2METRaf kinaseSteroid ReceptorsAktCDK4Hif1a

Ansamycins bind the ADP/ATP switch site in Hsp90

Tumour regressions only seen in heavily pretreated HER2+ patients

Best response and target lesion change (n=25)*

* One additional patient had complete regression of a single target lesion but overall response of progressive disease based on non-target lesions. One patient withdrawn for clinical progression without radiological assessment

Response rates for novel HER2-targeting agents after progression on trastuzumab

17-AAG Pertuzumab Neratinib

0

10

20

30

40

50

60

70

80

90

P<0.0001

Resp

onse

ra

tes

(%)

T-DM1

N=31 N=66N=45 N=112

Modi S et al, ASCO 2008; Gelmon KA et al, ASCO 2008; Swaby R et al, ASCO 2009; Burris HA et al, ESMO 2009

We have a good problem (many drugs) in HER2+ breast cancer – we are just learning how to combine them now

• Pertuzumab (anti-HER2 antibody)

• Irreversible HER2 kinase inhibitors (neratinib)

• HER3 antibodies (AMG-888, MM-121)

• PI3K inhibitors (GDC-0941, XL-147, BKM120)

• Akt inhibitors (MK-2206)

• IGF-IR inhibitors (R1507, MK-0646, OSI-906)

• HSP90 inhibitors

• Trastuzumab-DM1 (fusion toxin)

• Bevacizumab and other angiogenesis inhibitors

• MET, Src, and TGF inhibitors

Implications• There are several 2-drug combinations that can

aim at completely inhibiting the HER2 network and its output to PI3K– Lapatinib + trastuzumab– Trastuzumab + AMG-888– Trastuzumab + pertuzumab– Trastuzumab (or lapatinib) + a PI3K or a AKT inhibitor– Trastuzumb-DM1 + a PI3K or a AKT inhibitor

• Neoadjuvant therapy provides a space where these can be compared (using path CR as an endpoint)

• Some molecular phenotypes may be more sensitive to some specific combinations (i.e., tumors with PI3K pathway mutations)

• Although efficacy may be equivalent, toxicity and cost will be major differentiating factors

Acknowledgements

Vanderbilt Charles ManningWilliam Pao

Baylor (Houston) Jenny ChangBhuvanesh Dave

Stanford Anne Brunet

AMGEN-U3 Dan FreemanRobert RadinskyThore Hetmann

Novartis Carlos Garcia-Echeverria