the kras oncogene

R.G. AmadoR.G. Amado

Analysis of Analysis of KRASKRAS Mutations in Patients With Mutations in Patients With Metastatic Colorectal Cancer Receiving Metastatic Colorectal Cancer Receiving

Panitumumab MonotherapyPanitumumab Monotherapy

Abstract 0007:Abstract 0007: Wild-type Wild-type KRASKRAS is Required for Panitumumab is Required for Panitumumab Efficacy in Patients With Metastatic Colorectal Cancer: Results Efficacy in Patients With Metastatic Colorectal Cancer: Results From a Randomized, Controlled TrialFrom a Randomized, Controlled Trial

Rafael G. Amado, Michael Wolf, Dan Freeman, Marc Peeters, Rafael G. Amado, Michael Wolf, Dan Freeman, Marc Peeters, Eric Van Cutsem, Salvatore Siena, Sid Suggs, Scott Patterson, David ChangEric Van Cutsem, Salvatore Siena, Sid Suggs, Scott Patterson, David Chang

Abstract 3014Abstract 3014: Association of Somatic : Association of Somatic KRASKRAS Gene Mutations and Gene Mutations and Clinical Outcome in Patients With Metastatic Colorectal Cancer Clinical Outcome in Patients With Metastatic Colorectal Cancer Receiving Panitumumab MonotherapyReceiving Panitumumab Monotherapy

Dan Freeman, Todd Juan, Neal J. Meropol, J. Randolph Hecht, Dan Freeman, Todd Juan, Neal J. Meropol, J. Randolph Hecht, Jordan Berlin, Eric Van Cutsem, Maureen Reiner, Robert Radinsky, Jordan Berlin, Eric Van Cutsem, Maureen Reiner, Robert Radinsky, Rafael G. Amado, Marc PeetersRafael G. Amado, Marc Peeters


The The KRASKRAS Oncogene Oncogene

• TheThe KRAS KRAS gene encodes the human cellular homolog of gene encodes the human cellular homolog of the transforming gene Kirsten rat sarcoma-2 virusthe transforming gene Kirsten rat sarcoma-2 virus

• KRAS is a self-inactivating signal transducerKRAS is a self-inactivating signal transducer

– It cycles from GDP bound (“off” state) to GTP bound It cycles from GDP bound (“off” state) to GTP bound (“on” state) in response to receptor activation(“on” state) in response to receptor activation

– This response is transient due to the intrinsic GTPase This response is transient due to the intrinsic GTPase activityactivity

• KRASKRAS oncogenes harbor activating mutations yielding oncogenes harbor activating mutations yielding proteins with reduced GTPase activityproteins with reduced GTPase activity

• These activating These activating KRASKRAS mutations are among the most mutations are among the most common oncogenic alterations in cancercommon oncogenic alterations in cancer11

1Malumbres and Barbacid. Nat Rev Cancer. 2003;3:459-465.


EGFr Signal TransductionEGFr Signal Transduction

Akt

SOS

FOS Myc

P13K

FKHRmTOR

PTEN

MEK 1/2

MAPK

BADGSK-3

Shc

Grb-2

Ras

Raf

Junp27

Cyclin D-1

LigandLigandLigandLigand

SignalSignalAdaptersAdaptersand Enzymesand Enzymes

SignalSignalCascadeCascade

EGFREGFR dimerdimer

TranscriptionTranscriptionFactorsFactors

STAT


WT, wild type; MT, mutant; cmab, cetuximab; CT, chemotherapy; pmab, panitumumab

Objective Response

N (%)

ReferenceTreatment

(panitumumab or cetuximab)No of patients

(WT:MT)MT WT

A. Liévre, et al. (AACR Proceedings, 2007) cmab ± CT 76 (49:27) 0 (0) 24 (49)

S. Benvenuti, et al. (Cancer Res, 2007) pmab or cmab or cmab + CT 48 (32:16) 1 (6) 10 (31)

W. De Roock, et al.(ASCO Proceedings, 2007) cmab or cmab + irinotecan 113 (67:46) 0 (0) 27 (40)

D. Finocchiaro, et al. (ASCO Proceedings, 2007) cmab ± CT 81 (49:32) 2 (6) 13 (26)

F. Di Fiore, et al. (Br J Cancer, 2007) cmab + CT 59 (43:16) 0 (0) 12 (28)

S. Khambata-Ford, et al. (J Clin Oncol, 2007)

cmab 80 (50:30) 0 (0) 5 (10)

Single-Arm Studies Support the Hypothesis for Single-Arm Studies Support the Hypothesis for KRASKRAS as a Biomarker for EGFr Inhibitors as a Biomarker for EGFr Inhibitors


KRASKRAS Analysis of Single-Arm, Analysis of Single-Arm, Panitumumab Monotherapy StudiesPanitumumab Monotherapy Studies

• Patient samples from 3 Amgen panitumumab monotherapy, Patient samples from 3 Amgen panitumumab monotherapy, single-arm, phase 2 trials in metastatic colorectal cancer single-arm, phase 2 trials in metastatic colorectal cancer were obtained under an ancillary biomarker protocolwere obtained under an ancillary biomarker protocol

• The majority of patient samples were archived tumor The majority of patient samples were archived tumor samples from the primary resectionsamples from the primary resection

• KRASKRAS mutational status was determined using cloning and mutational status was determined using cloning and sequencing of DNA isolated from paraffin-embedded tumor sequencing of DNA isolated from paraffin-embedded tumor samplessamples

• KRASKRAS mutational status was correlated with clinical mutational status was correlated with clinical outcomes including response, progression-free survival, outcomes including response, progression-free survival, and overall survivaland overall survival


Objective Tumor ResponseObjective Tumor Response

All Patients Mutant KRAS Wild-type KRAS

Total (N = 62)

Total (N = 24)

Total (N = 38)

PR, n (%) 4 (6.5) 0 4 (11)

SD, n (%) 25 (40) 5 (21) 20 (53)

PD, n (%) 33 (53) 19 (79) 14 (37)

PR + SD, n (%) 29 (47) 5 (21) 24 (63)

PR partial response; SD, stable disease; PD, disease progression


Progression-Free Survival for Panitumumab-Progression-Free Survival for Panitumumab-Treated Patients by Treated Patients by KRASKRAS Status Status

_Median (95% CI) in Weeks

Mutant: 7.4 (7.1–8.0)

-- Wild-type: 16.2 (8.3–23.7)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Pro

po

rtio

n w

ith

PF

S

5550454035302520151050

2438

Patients at Risk:MutantWild-type

2438

625

625

417

314

213

27 6 3 3

Weeks From Enrollment


Randomization stratification• ECOG score: 0-1 vs. 2• Geographic region: Western EU vs. Central & Eastern EU vs. Rest of World

1:1

Panitumumab PD Follow-up6.0 mg/kg Q2W+ BSC

BSC PD Follow-up

RANDOMIZE

Optional Panitumumab

Crossover Study

Hypothesis: The treatment effect of panitumumab monotherapy is larger in patients with wild-type KRAS compared to patients with mutant KRAS

KRAS Analysis of a Phase 3, Randomized, Controlled Trial Comparing Panitumumab vs Best

Supportive Care (BSC) in Colorectal Cancer

Van Cutsem, Peeters et al. JCO. 2007;25:1658-1664.


Objectives and Analysis MethodologyObjectives and Analysis MethodologyPrimary Objective

• To assess if the effect of panitumumab on progression-free survival (PFS) was significantly greater in patients with wild-type KRAS compared to patients with mutant KRAS

Secondary Objectives

• To assess whether panitumumab improves PFS compared with BSC alone in patients with wild-type KRAS

• To assess whether panitumumab improves OS compared with BSC alone in patients with wild-type KRAS

Compare PFS in wild-type KRAS

subset

Test for a PFS effect among all

randomized patients at a 5% level

Test for quantitative PFS effect interaction,

i.e., wild-type effect > mutant

p ≤ 0.05 p > 0.05

p ≤ 0.05 p > 0.05

Compare OR & OS in wild-type KRAS subset STOP

STOP


Assay Used to Detect Assay Used to Detect KRASKRAS Mutational Status Mutational Status

• DNA was isolated from fixed tumor samplesDNA was isolated from fixed tumor samples

• Mutant Mutant KRASKRAS was detected using a was detected using a KRASKRAS mutation kit (DxS Ltd, mutation kit (DxS Ltd, Manchester, UK) that used allele-specific, real-time PCRManchester, UK) that used allele-specific, real-time PCR

– The kit can detect approximately 1% of mutant DNA in a The kit can detect approximately 1% of mutant DNA in a background of wild-type genomic DNAbackground of wild-type genomic DNA

– The test identifies 7 somatic mutations in codons 12 and 13The test identifies 7 somatic mutations in codons 12 and 13

• Gly 12 AspGly 12 Asp

• Gly 12 AlaGly 12 Ala

• Gly 12 ValGly 12 Val

• Gly 12 SerGly 12 Ser

• Gly 12 Arg• Gly 12 Cys• Gly 13 Asp


Results: Prevalence of Mutant Results: Prevalence of Mutant KRASKRAS

Panitumumab+ BSC

BSC alone Total

Patients randomized, n 231 232 463

KRAS not tested, n (%) 11 (5) 7 (3) 18 (4)

KRAS tests failed, n (%) 12 (5) 6 (3) 18 (4)

Patients included in KRAS analysis, n (%)

208 (90) 219 (94) 427 (92)

Wild-type KRAS, n (%) 124 (60) 119 (54) 243 (57)

Mutant KRAS, n (%) 84 (40) 100 (46) 184 (43)

BSC, best supportive care


Distribution of Distribution of KRASKRAS Mutations Mutations

PanitumumabPanitumumab+ BSC+ BSC BSC aloneBSC alone TotalTotal

MutationMutation nn %% nn %% nn %%

12 Ala12 Ala 88 9.59.5 77 7.07.0 1515 8.28.2

12 Asp12 Asp 3434 40.540.5 3636 36.036.0 7070 38.038.0

12 Arg12 Arg 00 0.00.0 33 3.03.0 33 1.61.6

12 Val12 Val 1515 17.917.9 2525 25.025.0 4040 21.721.7

12 Cys12 Cys 77 8.38.3 77 7.07.0 1414 7.67.6

12 Ser12 Ser 55 6.06.0 99 9.09.0 1414 7.67.6

13 Asp13 Asp 1515 17.917.9 1414 14.014.0 2929 15.815.8


Baseline Disease Characteristics Baseline Disease Characteristics KRASKRAS Evaluable Group Evaluable Group

KRAS Evaluable

Mutant KRASWild-type

KRASTotal

(N = 427)Total

(N = 184)Total

(N = 243) Sex, n (%) Men 270 (63) 111 (60) 159 (65) Baseline age, years Median (min, max) 62.0 (27, 83) 62.0 (27, 83) 63.0 (29, 82) Primary diagnosis, n (%) Colon cancer 286 (67) 118 (64) 168 (69)

Months since primary diagnosis

Median 25.1 24.1 25.1 ECOG performance status, n (%) 0-1 366 (86) 155 (84) 211 (87) ≥ 2 61 (14) 29 (16) 32 (13) Prior adjuvant chemotherapy, n (%) Yes 149 (35) 67 (36) 82 (34) Cells with EGFr membrane staining, n (%) 1% to < 10% 103 (24) 43 (23) 60 (25) 10% to 100% 322 (75) 140 (76) 182 (75)ECOG, Eastern Cooperative Oncology Group; EGFr, epidermal growth factor receptor


KRASKRAS Evaluable Patients: Evaluable Patients:PFS by TreatmentPFS by Treatment

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

Weeks

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

36 38 40 42 44 46 48 50 52

197188178 106 79 71 64 55 50 49 49 37 29 25 24 19 15 15 15 12 9 9 7 6 6200168142 75 42 34 25 23 19 16 14 14 10 10 10 10 9 8 6 6 5 4 4 4 3

208219

Pro

po

rtio

n w

ith

PF

S

Pmab + BSCBSC Alone

Patients at Risk

191/208 (92) 8.0 15.4209/219 (95) 7.3 9.6

Pmab + BSCBSC Alone

Events/N (%)Median

In WeeksMean

In Weeks

HR = 0.59 (95% CI: 0.48–0.72)


Mutant Mutant KRASKRAS Subgroup: Subgroup:PFS by TreatmentPFS by Treatment

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Pro

po

rtio

n w

ith

PF

S

Pmab + BSCBSC Alone

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

Weeks

36 38 40 42 44 46 48 50 52

Patients at Risk

78 76 72 26 10 8 6 5 5 5 5 4 4 4 4 2 2 2 2 2 2 2 1 1 191 77 61 37 22 19 10 9 8 6 5 5 4 4 4 4 4 4 3 3 3 2 2 2 2

84100

76/84 (90) 7.4 9.995/100 (95) 7.3 10.2

Pmab + BSCBSC Alone

Events/N (%)Median

In WeeksMean

In Weeks

HR = 0.99 (95% CI: 0.73–1.36)


Wild-type Wild-type KRASKRAS Subgroup: PFS by Treatment Subgroup: PFS by Treatment

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

Weeks

36 38 40 42 44 46 48 50 52

7 7 6 5 510 9 9 6 6 6 5 4 3 3 2 2 2 2 1

124

115/124 (93) 12.3 19.0114/119 (96) 7.3 9.3

Pmab + BSCBSC Alone

Events/N (%)Median

In WeeksMean

In Weeks

HR = 0.45 (95% CI: 0.34–0.59)Stratified log-rank test, p < 0.0001

Pmab + BSCBSC Alone

Patients at Risk

119 112 106 80 69 63 58 50 45 44 44 33 25 21 20 17 13 13 13 10119 109 91 81 38 20 15 15 14 11 6

Pro

po

rtio

n w

ith

PF

Sp < 0.0001 for quantitative-interaction test comparing PFS log-HR

(pmab/BSC) between KRAS groups


0.17-0.47

Wild-Type Wild-Type KRASKRAS Subgroup: Subgroup:Treatment Effect on PFS by Demographic/Disease StatusTreatment Effect on PFS by Demographic/Disease Status

HR, hazard ratio; Pmab, panitumumab; BSC, best supportive careAdjusted for randomization factors (ECOG score, geographic region)

All RandomizedMaleFemaleAge: < 65Age: 65+Primary: ColonPrimary: RectalECOG: 0–1ECOG: 2–3

Prior regimens: 3+Met. Sites: 1–2Met. Sites: 3–5EGFr: 1–< 10%EGFr: 10–35%EGFr: > 35%EGFr: 1+EGFr: 2+EGFr: 3+

Prior regimens: 3Prior regimens: 2

243159

84141102168

75211

32

100172

6960

1018169

12747

90142

0.450.420.460.420.470.470.360.470.35

0.270.420.520.300.490.340.330.410.37

0.280.54

0.34-0.590.30-0.590.29-0.730.29-0.600.31-0.730.34-0.650.21-0.610.35-0.620.15-0.82

0.17-0.440.30-0.590.30-0.890.16-0.560.31-0.750.20-0.580.18-0.630.28-0.600.18-0.75

0.38-0.76

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2Hazard Ratio (Pmab/BSC)

Favors: Pmab BSCFactors N HR 95% CI


Objective Tumor Response Objective Tumor Response (Central Radiology)(Central Radiology)

KRAS

All Evaluablen (%)

Mutantn (%)

Wild-typen (%)

ResponsePmab

(N = 208)

BSC

(N = 219)

Pmab

(N = 84)

BSC

(N = 100)

Pmab

(N = 124)

BSC

(N = 119)

CR 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)

PR 21 (10) 0 (0) 0 (0) 0 (0) 21 (17) 0 (0)

SD 52 (25) 22 (10) 10 (12) 8 (8) 42 (34) 14 (12)

PD 104 (50) 149 (68) 59 (70) 60 (60) 45 (36) 89 (75)

CR, PR, SD 73 (35) 22 (10) 10 (12) 8 (8) 63 (51) 14 (12)

Pmab, panitumumab; BSC, best supportive care; CR, complete response; PR partial response; SD, stable disease; PD, disease progression


Objective Tumor Response Objective Tumor Response Extension Study 20030194Extension Study 20030194

(Investigator assessment)(Investigator assessment)

KRAS

All Evaluable

n (%)

Mutant

n (%)

Wild-type

n (%)

Response Pmab

(N = 168)

Pmab

(N = 77)

Pmab

(N = 91)

CR 1 (1) 0 (0) 1 (1)

PR 19 (11) 0 (0) 19 (21)

SD 55 (33) 20 (26) 35 (38)

PD 60 (36) 37 (48) 23 (25)

CR, PR 20 (12) 0 (0) 20 (22)

CR, PR, SD 75 (45) 20 (26) 55 (60)

Pmab, panitumumab; CR, complete response; PR partial response; SD, stable disease; PD, disease progression


Maximum Percent Decrease in Target Lesions Maximum Percent Decrease in Target Lesions Final Analysis, Final Analysis, KRASKRAS Evaluable Group Evaluable Group

16014012010080604020%

Cha

nge

-20-40-60-80

0

PR (0%) SD (12%) PD (70%)

Mutant

Patient

Pmab+ BSC

16014012010080604020%

Cha

nge

-20-40-60-80

0

PR (17%) SD (34%) PD (36%)

Wild-Type

Patient

16014012010080604020

% C

hang

e

-20-40-60-80

0

PR (0%) SD (8%) PD (60%)

Patient

BSCAlone

16014012010080604020

% C

hang

e

-20-40-60-80

0

PR (0%) SD (12%) PD (75%)

Patient


Overall Survival by Treatment and Overall Survival by Treatment and KRASKRAS

124 92 58 35 18 9 3 2 1119 82 54 28 18 10 5 1 084 51 21 10 6 3 3 1 0100 55 30 18 11 3 0 0 0

Pmab–Wild-typeBSC–Wild-type

Pmab–MutantBSC–Mutant

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

Months

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Su

rviv

al P

rob

abili

ty

Pmab–Wild-type 107 / 124 (86)

110 / 119 (92)

8.1

7.6

Events/N (%)Median

In Months

BSC–Wild-type

Wild-type vs. Mutant(treatment arms combined)

Pmab–Mutant

BSC–Mutant

79 / 84 (94)

95 / 100 (95)

4.9

4.4

HR = 0.67 (95% CI: 0.55–0.82)(adjusted for treatment andrandomization factors; ECOG, region)


Overview of Safety From Overview of Safety From KRASKRAS Analysis Analysis ( (Panitumumab-Treated Patients)Panitumumab-Treated Patients)

KRAS

Evaluable

Mutant

KRAS

Wild-type

KRAS

Exposure: Mean number of infusions per patient 7.9 4.9 10.0

Any AE, % 100 100 100

Grade 3 or 4 AE, % 37 28 44

Treatment-related grade 3 AE, % 20 12 25

Any grade integument-related AE, % 92 90 93

Grade 3 20 13 25

Grade 4 < 1 1 0

Any grade diarrhea, % 22 19 24

Grade 3 2 1 2

Any grade infections, % 47 35 55

Grade 3 7 5 8

Hypomagnesemia as an AE, % 1 0 2

Infusion reactions, % 4 7 2

AE leading to withdrawal, % 6 5 7AE, Adverse Event


ConclusionsConclusions• The efficacy of panitumumab monotherapy in metastatic The efficacy of panitumumab monotherapy in metastatic

CRC seems confined to patients with wild-type CRC seems confined to patients with wild-type KRASKRAS

• KRASKRAS genotyping of tumors should be strongly genotyping of tumors should be strongly considered in patients with metastatic CRC being treated considered in patients with metastatic CRC being treated with panitumumab monotherapywith panitumumab monotherapy

• Ongoing studies in 1Ongoing studies in 1stst and 2 and 2ndnd lines will prospectively lines will prospectively examine the effect of panitumumab in combination with examine the effect of panitumumab in combination with chemotherapy in patients with wild-type and mutant chemotherapy in patients with wild-type and mutant KRAS KRAS tumorstumors

• Future studies should investigate the role of Future studies should investigate the role of KRASKRAS mutational status in the adjuvant setting in colon cancer mutational status in the adjuvant setting in colon cancer and in other indicationsand in other indications


AcknowledgmentsAcknowledgments

• We wish to thank the patients and their families for We wish to thank the patients and their families for study participationstudy participation

• We also thank all investigators and study We also thank all investigators and study personnelpersonnel

DisclosuresDisclosures

• This study was sponsored by Amgen Inc.• R.G. Amado, M. Wolf, D. Freeman, S. Suggs, S. Patterson, D. Chang,

T. Juan, M. Reiner, and R. Radinsky are Amgen employees and own Amgen Inc. stock.

• M. Peeters, Amgen advisory board and Amgen honoraria; E. Van Cutsem, Amgen advisory board and Amgen honoraria; N.J. Meropol, consultant for Amgen, Genentech, and Imclone; J. Berlin, advisory boards for Amgen, BMS, and Imclone.

the kras oncogene

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