progress towards an individualized approach to therapy: colorectal cancer alan p. venook, m.d....

Progress towards an individualized approach to therapy: colorectal

cancerAlan P. Venook, M.D.

University of California, SF

Breast Cancer Oncologist Envy

Alan P. Venook, M.D.University of California, SF

Personalized decision-making: predicting risk:benefit

Personalized decision-making: predicting risk:benefit

Personalized decision-making: predicting risk:benefit

Personalized decision-making: predicting risk:benefit

Meropol, et al; JCO, 2007

Escalating cost of cancer care

“Predictive” vs. “Prognostic”

• Predictive: response to treatment

• Prognostic: independent of treatment

Variables: host (germline) tumor

Towards Personalized Therapy of Colon Cancer

• Tumor genetic profiling• Stage II colon cancer• Stage IV colorectal cancer

• Pharmacogenetics• Oxaliplatin efficacy• Irinotecan - UGT1A1

• Therapeutic Drug Monitoring

CRC Stage at Diagnosis

13.7% Stage I

27.9% Stage II37.2% Stage III

21.2% Stage IV

Treatment Algorithms: Colorectal Cancer 5th Edition. Datamonitor 2003.

Colorectal Cancer: TNM Staging System

• Extent of invasionthrough bowel wall (T)

• Extent of LN metastases (N)

• Presence of distant metastases (M)

Renouf et al, Clin Col Can, 2008

QASAR, Lancet, 2007

QASAR, Lancet, 2007

Colorectal Cancer, 2007

18Q deletion & outcome in untreated colorectal cancer

18Q +

18Q -

Jen, et al. NEJM, 1994

mFOLFOX6

v.

mFOLFOX6 +Bevacizumab qow

Accrual Goal: 3,125

Tumor risk assessed based on biology (18q/MSI)

High-risk (MSS and 18q LOH)

Low-risk (MSI + or no loss 18q) OBSERVATION

Surgery

E5202 – Stage II Colon Cancer

Khambata-Ford, JCO, 2007

Towards Personalized Therapy:

Stage II Colon Cancer• MSI and del 18q• Microarrays• Composite of prognostic and predictive genes• Nodal analysis

Towards Personalized Therapy: Tumor Genetics

• EGF-R antibodies: yes or no?• KRAS• BRAF• PTEN

• VEGF antibody: yes or no?

Personalized Therapy: Tumor Genetics

• EGF-R antibodies• KRAS• BRAF• PTEN

The Ras Oncogene

• 100% of mice developed tumors in weeks• Rapid development of sarcomas and erythroleukemias

Kirsten and Harvey: 1964Identification of a virus that produced tumors in mice

HaMSVKiMSV

Harvey (1964) Nature 204:1104; Somers and Kirsten Science 1967;40:1053

Ras Family of Proteins• Monomeric G proteins (H-Ras, K-Ras and N-Ras)

• Respond to activation of membrane-associated receptors for cell growth and survival

• Cycle between GDP bound “off” state and GTP bound “on” state

• Act as “molecular switches” linking extracellular signals through membrane receptors to intracellular signals

Copyright ©2008 American Association for Cancer Research

Sebolt-Leopold, J. S. Clin Cancer Res 2008;14:3651-3656

Ras: Downstream Signaling

Ras mutations: 30% of Human Cancers

Pancreatic carcinoma 72-90%Cholangiocarcinoma 55%Colon adenocarcinoma 32-57%Thyroid carcinoma 30%Seminoma 40%Embryonal rhabdomyosarcoma 35%Acute myelogenous leukemia 35%Myeloblastic syndromes 30%Lung carcinoma 15-50%

CRC: Adenoma-Carcinoma Sequence

32-57%K-Ras mutant

Detecting tumor K-Ras mutations

• DNA extracted from tumor (FFPE, cell-free DNA)

• Mutational analysis by sequencing (various methods) or mutant allele specific amplification

• Detection threshhold:

• 1% of mutant DNA in a background of wild-type genomic DNA

• Gly 12 Asp• Gly 12 Ala• Gly 12 Val• Gly 12 Ser

Single base substitutions thatrender GTPase domain insensitive to inactivation by GAP

• Gly 12 Arg• Gly 12 Cys• Gly 13 Asp

Prognostic implications: K-Ras

Probably NOSmakman et al; Biochem Biophys Acta 2005; 1756:103

• Stage I-IV CRC; 24 studies with >100 patients (range 100-3439)• Mutation rate 24-69%

• Association between K-Ras status and stage:• Yes: 7; No: 13; N/A: 4

• Association between K-Ras status and DFS:• Yes: 3; No: 3; N/A: 18

Retrospective studies supporting K-ras and lack of anti-EGFR response

Advanced CRC treated with cetuximab: case series N=30

Lievre, A. et al. Cancer Res 2006;66:3992-3995

Most with prior irinotecan exposure

97% irinotecan + cetuximab

Single agent cetuximab: N=80

Khambata-Ford et al J Clin Oncol, 2007; 25: 3230-3237

Single agent panitumumab: N=208

K-Ras Mutation Wild-Type K-Ras

Amado RG, et al. J Clin Oncol. 2008;26:1626-1634.

Panitumumab registration trial

CRYSTAL

RANDOMI

Z E

FOLFIRIFOLFIRI

FOLFIRI + CetuximabFOLFIRI + Cetuximab

n = 540

Van Cutsem ASCO 2008; JCO 28: May 20 suppl; abstr 2.

FOLFIRI

FOLFIRI + Cetuximab

P value

K-ras wildtype K-ras mutant

HR 0.68 HR 1.07

(0.051-0.934)

0.017

(0.71-1.61)

0.75

CALGB/SWOG 80405 Study Design

Untreatedadvancedor mCRCN = 2600

Bevacizumabfollowed by

FOLFOX or FOLFIRIq 2 wks

Cetuximabfollowed by

FOLFOX or FOLFIRIq 2 wks

Cetuximabfollowed by

Bevacizumabfollowed by FOLFOXor FOLFIRI q 2 wksOne cycle=8 weeks

mCRC=metastatic colorectal cancer

Open-label Phase III Study

Screenfor

eligibility

Sendtumortissue

block toSWOGPCO

RandomizePatients

w/Wild type

K-ras tumor

RegisterPatient

Copyright ©2008 American Association for Cancer Research

Sebolt-Leopold, J. S. Clin Cancer Res 2008;14:3651-3656

Ras: Downstream Signaling

DiNicolantonio et al, JCO, 2008

DiNicolantonio et al, JCO, 2008

Copyright ©2008 American Association for Cancer Research

Sebolt-Leopold, J. S. Clin Cancer Res 2008;14:3651-3656

Ras: Downstream Signaling

44th ASCO Annual Meeting May 30-June 3, 2008McCormick Place, Chicago, Illinois

Evaluation of PTEN expression in colorectal cancer (CRC) metastases (mets) and in primary

tumors as predictors of activity of cetuximab plus irinotecan

treatment

F. Loupakis1,6, L. Pollina2, I. Stasi1, G. Masi1, N. Funel2, M. Scartozzi3, I. Petrini4, D. Santini5, S. Cascinu3, A.

Falcone1,6.1Department of Oncology, Azienda USL 6 - Istituto Toscano Tumori Livorno, Italy,

2Division of Pathology, AOUP, Pisa, Italy, 3Division of Medical Oncology, Azienda Ospedaliera Ospedali Riuniti,

Università Politecnica delle Marche, Ancona, Italy,4Division of Medical Oncology, AOUP, Pisa, Italy,

5Division of Medical Oncology, Campus Biomedico University, Rome, Italy, 6Department of Oncology, Transplants and New Technologies in Medicine, University

of Pisa, Italy

PTEN

PIP3

Ligands

AKT

Nucleus

EGF receptor

mTOR

PIP2

• PTEN (phoshatase and tensin homologue deleted on chromosome 10) gene encodes a phosphatase, whose major substrate is PIP-3

• Loss of PTEN (mono or bi-allelic inactivation, but also epigenetic silencing) results in increased PIP-3 concentration

• Increase of PIP-3 leads to AKT hyperactivation

PROTECTION FROM APOPTOSIS

PTENPI3K

CONCLUSIONSCONCLUSIONS

Primaries and related mets from CRC differed in terms of PTEN immunoreactivity in 40% of cases.

KRAS mutations found on primaries are almost always (95% of cases) confirmed on mets. Such analysis may be ruled out on any available tumor sample.

Loss of PTEN tested on mets predicted lack of activity of cetuximab plus irinotecan combination treatment in metastatic CRC pts.

KRAS is confirmed to be a predictor of resistance to cetuximab plus irinotecan combination treatment in metastatic CRC pts.

The combination of PTEN IHC performed on mets and KRAS mutational analysis identified a subgroup of patients with higher chances of benefiting from cetuximab plus irinotecan treatment.

PTEN: remaining challenges

• Reproducible assay• Immunohistochemistry • Gene copy number• Sequence

• Proving predictive / prognostic value

Wong et al, JCO, 2008

Towards Personalized Therapy of Colon Cancer

• Tumor genetic profiling• Stage II colon cancer• Stage IV colorectal cancer

• Pharmacogenetics• Oxaliplatin efficacy• Irinotecan - UGT1A1

• Therapeutic Drug Monitoring

Genetics and Pharmacokinetics / Pharmacodynamics

Pharmacokinetics-Absorption-Distribution-Metabolism-Excretion

PharmacodynamicsTumor Host

Response Toxicity

DoseCompliance

Pharmacogenetics

H. L. McLeod, K. Owzar, D. Kroetz, F. Innocenti, S. Das, P. Friedman, K. Giacomini, R. Goldberg, A. Venook, M. J. Ratain

Univ of North Carolina-Chapel Hill, Chapel Hill, NC; Duke, Durham, NC; UCSF, San Francisco, CA; University of Chicago, Chicago, IL; CALGB, Chicago, IL

Cellular transporter pharmacogenetics in metastatic colorectal cancer: initial analysis of C80203

Predicting oxaliplatin efficacy?

• Genomic DNA from 180/238 patients on C80203 (FOLFOX vs. FOLFIRI +/- cetuximab)

• Genotype transporter genes involved in irinotecan and oxaliplatin clearance:• ABCC2, ABCC4, ABCG2, SLCO1B1, SLC22A1, SLC22A2

• Association of genotype with response and toxicity

• Result:• ABCG2 34 G>A associated with response to FOLFOX, resistance to FOLFIRI but not to toxicity

Irinotecan pathwayCPT-11

cell membrane

CPT-11

CPT-11

SN-38

SN-38

SN-38TOP1

Cell Death

APC

SN-38G

ABCB1

CYP3A4

CYP3A5CES1

CES2

UGT1A1

CES1

CES2

ABCC2

ABCG2

ABCC1

ADPRT

TDP1

CDC45L

XRCC1

NFKB1

NPC

ABCB1

UGT1A1: promoter polymorphism and toxicity

UGT1A1 gene structure Iyer et al 2002

UGT1A1 TA repeat: irinotecan neutropenia/activity

35.7

16.3

8.6

0

5

10

15

20

25

30

35

40

45

50

6/6 6/7 7/7

P=0.007

UGT1A1 genotype

% g

rade

4/5

neu

trop

enia

McLeod et al, ASCO 2003

N=524

41.9

33.8

14.3

05

1015202530354045

6/6 6/7 7/7

UGT1A1 genotype

Obj

ectiv

e re

spon

se (

%)

P=0.045

Camptosar package insert, May 2005

Towards Personalized Therapy of Colon Cancer: Pharmacogenetics

• Oxaliplatin efficacy• Rare polymorphism• Small sample size

• Irinotecan toxicity• Regimen depednent• Not all or none

• VEGF antibody efficacy• Polymorphisms?

• Cetuximab efficacy• FCR polymorphisms?

Towards Personalized Therapy of Colon Cancer

• Tumor genetic profiling• Stage II colon cancer• Stage IV colorectal cancer

• Pharmacogenetics• Oxaliplatin efficacy• Irinotecan - UGT1A1

• Therapeutic Drug Monitoring

Drug ReceptorGenotypes

Drug MetabolismGenotypes

TherapeuticEffect (%)

Toxicity(%)

+ = Genetically RegulatedHeterogeneity in Drug Effects

Genetic Polymorphismof Drug Sensitivity

Genetic Polymorphismof Drug Exposure

E fficacyTox ic ity

1

1

1

100

50

00 50 100

wt/wt

wt/m

m/m

75

35

10

100

50

00 24 hr

30

A.wt/wt

>80

>80

>80

Drug Concentration

100

50

00 50 100

wt/wt

wt/m

m/m

100

50

00 24 hr

99

Time

m / mC. 95

50

10

<10

<10

<10

100

50

00 100

wt/wt

wt/m

m/m

100

50

00 24 hr 50

65

wt/mB.

85

45

10

Evans WE and Relling MV, Science 286:487-91, 1999

Biochemical Pathways of 5-FU Metabolism

Au et al.,1982 5D CVI, CRC Leucopenia Cpss > 1.5 µM

Trump et al., 1991 3D CVI, CRC Leucopenia Cpss

Yoshida et al.,1990 7D CVI, CRC Leucopenia AUC > 33

mg/h.L

Thyss et al.,1986 5D CVI, HNC Leucopenia AUC 30 mg/h.L

Vokes et al., 1996 3D CVI, HNC Leucopenia Cpss

Reference Schedule, Tumor Toxicity PK variable, threshold

AUC: Area under the curve; CCR: Colorectal cancer; Cpss: Steady state plasma concentration; CVI: Continuous venous infusion; HNC: Head and Neck Cancer IVB: Intravenous bolus

Hillcoat et al., 1978 5D CVI, CRC 36.1 19.2

Yoshida et al.,1990 7D CVI, CRC 27.4 22.5

Milano et al.,1994 5D CVI, HNC 29.727.2

Vokes et al., 1996 5D CVI, HNC 27.5 21.0

Reference Schedule, Tumor AUC AUC

(mg/h.L) (mg/h.L)

(Responder) (Non-Responder)

AUC: Area under the curve; CCR: Colorectal cancer; CVI: Continuous venous infusion;

HNC: Head and Neck Cancer; LV: Leucovorin

Studies Correlating Systemic Exposure with Tumor Response for 5-FU Infusional

Regimen

Relationship between Systemic Exposure Relationship between Systemic Exposure

and survivaland survival

Milano et al., J Clinical Oncology 1994; 12: 1291Milano et al., J Clinical Oncology 1994; 12: 1291

Remaining questions include:

• What is the target therapeutic range?• For toxicity• For efficacy• With oxaliplatin

• When to sample?• Would clinicans do this?• Is this important?

Opportunities for TDM

• Most oral chemotherapy drugs• Imatinib• Sorafenib• Sunitinib

• Taxanes• Biologics

GI Stromal Tumor Oncologist Envy

Joensuu et al. N Engl J Med. 2001;344:1052. Copyright 2001 Massachusetts Medical Society.

GIST: PET change after 4 weeks imatinib

Multiple liver and upper abdominal 18FDG-accumulating metastases

A marked decrease in 18FDG uptake 4 weeks after starting imatinib

Overall Survival by Genotype (Kaplan-Meier Estimate)

Joensuu H et al. Eur J Cancer. 2007;5(suppl):404. Abstract 7506.

over all KIT mutation groups

Von Mehren, ASCO, 2008

Towards Personalized Therapy of Colon Cancer

• Tumor genetic profiling• Nearing clinical reality for stage II patients• KRAS a standard; BRAF coming; others pending

• Pharmacogenetics• Complex

• Therapeutic Drug Monitoring• Is there enough benefit to justify the effort?

• Can we change the paradigm for clinical trials?