Analysis of FcReceptor IIA and IIIA Polymorphisms: Correlation with Outcome in Trastuzumab-Treated

Her2/neu Amplified Early and Metastatic Breast Cancer Patients

POSITIVE DISCLOSURES

Dr. Hurvitz received research/grant support from Genentech/RocheDr. Stern is an employee of Genentech and stockholder in RocheJeremy Stinson is an employee of Genentech and stockholder in

RocheDr. Seshagiri is an employee of Genentech and stockholder in

RocheDr. Robert receives research/grant support from Genentech and is

on the Roche Speakers’ BureauDr. Valero receives research/grant support from Genentech/Roche

and is on the Roche Speakers’ BureauDr. Crown receives research/grant support from Roche and is on

the Roche Speakers’ BureauDr. Slamon is on the speakers’ bureau for Genentech

Analysis of Fc Receptor IIa and IIIa Polymorphisms: Correlation with Outcome in

Trastuzumab-Treated Her2/neu Amplified Early and Metastatic Breast Cancer Patients

Sara A. Hurvitz, David Betting, Howard M. Stern, Emmanuel Quinaux, Jeremy Stinson, Somasekar Seshagiri, Ying Zhao, Marc Buyse, John Mackey, Nicholas J. Robert, Vicente Valero, John Crown, Adrian Driga, Valerie Bee,

Dennis J. Slamon, John M. Timmerman

Abstract 64

1. Growth Factor Receptor BlockadeInactivation of AKT signalingDecreased Cell Proliferation

Induction of Apoptosis

Tumor Cell

Trastuzumab: αHer2-Monoclonal IgG1 Antibody Postulated Mechanisms of Action

Preclinical evidence for role of ADCC: Efficacy of trastuzumab against breast cancer xenografts was largely dependent on FcR bindingClynes et al. Nature Med. 2000;6:443-446

2. FcR engagement (e.g. Antibody-Dependent Cellular Cytotoxicity, ADCC)

NK Cell

FcR

Human FcRIIIa (CD16) polymorphisms

Wu et al, J. Clin. Invest.100:1059, 1997.Lehrnbecher, Blood, 1999;94;4220-4232.

• FcRIIIa is expressed on both NK cells and macrophages; ADCC effectors in vivo

• Gene dimorphism encoding FcRIIIa: phenylalanine (F) or a valine (V) at position 158

• This residue interacts with IgG1 Fc

• Human IgG1 binds more strongly to homozygous V/V NK cells than to others

• Frequency of genotype in population: 158 V/V 13%, V/F 47%, F/F 40%

Human FcRIIa (CD32) polymorphisms

Wu et al, J. Clin. Invest.100:1059, 1997.Lehrnbecher, Blood, 1999;94;4220-4232.

• Gene dimorphism encoding FcRIIa: histidine (H) or arginine (R) at position 131

• Human IgG1 binds more strongly to homozygous FcRIIa-131 H/H immune cells than to H/R or R/R

• Frequency in general population: 131 H/H 21%, H/R 58%, R/R 21%

FcR Genotype: Outcome with Monoclonal Ab Therapy

Rituximab anti-CD20-antibody for non-Hodgkin’s lymphoma:• FcRIIIa-158V/V and FcRIIa-131H/H genotypes

associated with improved response rates and PFS.

Question: Does FcR genotype play a role in the response to trastuzumab?

Such an association would:• provide evidence that the immune system plays a role in

the anti-tumor activity of trastuzumab• support the development of engineered monoclonal

antibodies with an increased affinity for FcR to improve drug efficacy

Cartron, Blood 2002;99:754-758. Weng, W-Ki, et al. JCO 2003

Previous studies of FcR genotypes in trastuzumab-treated breast cancer:

Discordant Results Foster, et al1: No association between FcRIIIa genotype and response in retrospective analysis of trial evaluating trastuzumab monotherapy in relapsed MBC (N=63)

Musolino et al, 20082: Assessed role of FcR genotypes in predicting efficacy of trastuzumab in 54 Her2+ MBC receiving trastuzumab + taxane.

1. Foster, Ostland, Mass, et al. Proceedings ASCO, 2002. 21(Abstract No: 227)2. Musolino et al. J Clin. Oncol. 2008: 26

FcRIIIa FcRIIa

Purpose

Determine whether FcRIIIa 158 V/F and/or FcRIIa 131 H/R genotypes are associated with disease free survival (DFS) in large cohort of patients with Her2/neu-amplified early stage breast cancer treated with trastuzumab.

In a separate cohort of Her2+ metastatic breast cancer patients treated with trastuzumab, determine whether FcRIIIa158 V/F and/or FcRIIa131 H/R genotypes are associated with time to progression (TTP).

Methods

• Serum & whole blood samples from breast cancer patients treated in the BCIRG-006 study who signed optional consent to have samples taken

• Genotype (FcRIIIA 158V/F and FcRIIA 131 H/R) was determined by Sanger sequencing and Sequenom mass spectrometry

• DFS was calculated by Kaplan-Meier and compared using log-rank test using data from third planned analysis

4 x AC60/600 mg/m2

4 x Docetaxel100 mg/m2

6 x Docetaxel and Carboplatin75 mg/m2 AUC 6

1 Year Trastuzumab

N=3,222

1 Year Trastuzumab

ACT

ACTH

TCH

Her 2+(Central FISH)

N+or high risk N-

4 x AC60/600 mg/m2

4 x Docetaxel100 mg/m2

BCIRG 006

Stratified by Nodes and Hormonal Receptor Status

Slamon et al. SABCS 2006

Arm Total in Trial FcγR IIIA FcγR IIA

AC-T 1,073 381 (36%) 387 (36%)

AC-TH 1,074 406 (38%) 415 (39%)

TCH 1,075 402 (37%) 416 (39%)

Total 3,222 1189 (37%) 1218 (38%)

Enrolled in BCIRG 006 (N=3,222)

FcR IIIA

Patients signed optional consent and samples sent in (N=1,286)

Genotyping failed (N=68)

FcRIIA

FcR IIIA (N=1,189)

FcR IIA (N=1,218)

Genotyping failed (N=97)

Did not consent or provide sample (N=1,936)

BCIRG 006 Subpopulation

Slamon et al, SABCS 2009BCIRG 006

BCIRG 006 Disease Free Survival3rd Planned Analysis – Overall Population

(N=3222)

Disease free survival:Subset of patients who were genotyped

Months

Pro

babi

lity

0.0

0.2

0.4

0.6

0.8

1.0

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90

Patients Events Treatment

414 88 AC-T

436 85 AC-TH

436 83 TCH

Months

Pro

ba

bili

ty

0.0

0.2

0.4

0.6

0.8

1.0

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90

Patients Events Risk group

414 88 AC-T872 168 AC-TH+TCH

Disease free survival (DFS):Genotyped patients with stratification

Stratified for major prognostic factors: age, LN, hormone receptor status, size, surgery type:

HR 0.74 [0.56, 0.98] p=0.036

Patient Characteristics

• Prognostic factors among the 3 FcRIIIA and 3 FcRIIA genotypes were well balanced for:

• Lymph node status• ER/PR status• Menopausal status • Tumor size• Age• Her2/neu FISH ratio

DFS Trastuzumab Arms FcRIIIa genotype

No statistically significant difference by genotype

Months

Pro

babi

lity

0.0

0.2

0.4

0.6

0.8

1.0

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90

Patients Events Risk group

113 20 V/V322 63 V/F373 74 F/F695 137 F carriers

(14%)

Log Rank p=0.98 (VV vs. VF vs. FF)

(40%)(46%)

Months

Pro

babi

lity

0.0

0.2

0.4

0.6

0.8

1.0

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90

Patients Events Risk group

213 41 H/H415 85 H/R203 39 R/R618 124 R carriers

DFS: Trastuzumab arms by FcRIIa genotype

No statistically significant difference by genotype

Log Rank p=0.76 (H/H vs. H/R vs. R/R)

(26%)(50%)(24%)

Months

Pro

babi

lity

0.0

0.2

0.4

0.6

0.8

1.0

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90

Patients Events Risk group

277 51 V/V and/or H/H595 117 Others

DFS: Trastuzumab Arms FcRIIIa-158V/V and/or FcRIIa-131/HH vs

Others

Log Rank p=0.67

Metastatic breast cancer cohort: Retrospective analysis

• Prospectively collected DNA from 53 women with Her2/neu amplified and/or overexpressed metastatic breast cancer treated with trastuzumab-based regimen

• FcRIIIA 158V/F and FcRIIA 131H/R genotypes determined

• Time to progression calculated from start of first exposure to trastuzumab to time of disease progression or death• Compared genotypes survival curves using log rank test• Cox proportional hazards regression model used for HRs

• Prior therapies in metastatic setting before receiving trastuzumab• 43 patients had no prior chemo • 10 pts had 1-4 prior chemo regimens

Time to Progression by FcR Genotype

No significant differences in TTP according to FcR genotypes

among 53 MBC patients treated with trastuzumab

N=6N=25N=21

N=15N=26N=12

FcRIIIa FcRIIa

Summary• BCIRG 006 Early Breast Cancer Cohort

• Largest FcR genotyping analysis of trastuzumab-treated breast cancer patients to date,

• We found no statistically significant correlation between FcRIIIa and FcRIIa genotypes and DFS.

• Limitations of study • Incomplete genotyping of entire study population• Trastuzumab benefit less robust in cohort of patients

with serum/whole blood available for genotyping• Despite this limitation, there appears to be no

statistically significant difference in outcome among genotypes

• Metastatic cohort• In 53 women with Her2/neu positive metastatic

breast cancer, we found no significant correlation between FcR genotypes and TTP

Conclusions

In contrast to the Musolino study, but similar to the Foster study, we saw no difference in clinical outcome based on FcR genotypes in both early and metastatic breast cancer cohorts.

These data do not support the hypothesis that polymorphism-related differences in FcR affinity cause differential outcome to trastuzumab therapy

AcknowledgementsDennis Slamon, MD, PhD

John Timmerman, MDJan Tillisch, MD

Mark Pegram, MDYiou Tseng

Mark Sliwkowski, PhDAnne Blackwood-Chirchir. MD

Mona Shing, MDFan Zhang, PhDDeepali Bhatt

ASCO Foundation, Young Investigator Award 2007NIH Loan Repayment Program

Genentech Research Grant

Patients