Department of GI Medical Oncology

ALPHABET SOUP: MAKING SENSE OF KRAS, BRAF, RAS AND OTHER BIOMARKERS

IN METASTATIC COLORECTAL CANCER

Cathy Eng, M.D., F.A.C.P.Associate Professor

Associate Medical Director, Colorectal CenterDirector of Network Clinical Research, GI Med Oncology

Co-Chairman, SWOG Rectal SubcommitteeApril 23, 2014

Cancers of the Colon and RectumInternational Statistics

Jemal et al: Cancer Epidemiol Biomarkers Prev; 19(8) August 2010; Siegel et al: CA Cancer J Clin 2014

Incidence

Mortality

1.2 Million

609,000

Worldwide

per annum

USA (2014)

Incidence

Mortality

136,830

50,310

Colorectal cancer is the 3rd most common cancer inmen and the 2nd in women.

Advances in the Treatment of Metastatic Colorectal Cancer

1980 1985 1990 1995 2000 2005

Therapeutic concepts

Palliative CTNeoadjuvant CT

CapecitabineOxaliplatin

Cetuximab

Bevacizumab

Irinotecan5-FU

Panitumumab Targeted therapies

{

5-FU = 5-fluorouracil; CT = chemotherapy.

{Cytotoxic chemotherapies

Ras

OS: 20M

OS: 32 months

AfliberceptRegorafenib

IFL

IFL + b

evaciz

umab

FOLFOX/Cap

eOx

FOLFOX/Cape

Ox + be

v

FOLFIRI

FOLFIRI +

beva

cizum

abmIFL

mIFL + be

vaciz

umab

0

5

10

15

20

25

30

15.6

20.3 19.9 21.323.1

28

17.619.2

First-Line Bevacizumab in mCRC: Overall Survival

*P<0.001; †P = 0.0769.1. Hurwitz H et al. N Engl J Med. 2004;350:2335-2342; 2. Saltz LB et al. J Clin Oncol. 2008;26:2013-2019; 3. Fuchs C et al. J Clin Oncol. 2007;25:4779-4786; 4. Fuchs C et al. J Clin Oncol. 2008;26:689-690;

OS

(mon

ths)

*

NO169662

AVF2107g1

BICC-C3,4

Approved Anti-VEGF Agents Antiangiogenic agent Description Target Approval

BevacizumabRecombinant humanized

monoclonal antibody VEGF-A

1st-line mCRC1,2:•FDA 2004•EMEA 20052nd-line mCRC1:•FDA 2006, 2013

Aflibercept Fully human fusion protein

VEGF-AVEGF-B

PIGF

2nd-line mCRC3,4:•FDA 2012•EMEA 2013,•TGA 2013

Regorafinib Small molecule TKI VEGFR-1,2 & 3 PDGFR-b,

TIE-2, FGFR-1, Ret, Kit, & Raf kinases

Salvage5,6:•FDA 2012•CHMP 2013•TGA 2013

CHMP, Committee for Health and Medicine Products; EMEA, European Medicines Agency; FDA, United States Federal Drug Administration, FGFR, fibroblast growth factor receptor; PDGFR, platelet-derived growth factor receptor; PlGF, placental growth factor; TKI, tyrosine kinase inhibitor; VEGF, vascular endothelial growth factor; VEGFR, vascular endothelial growth factor receptor .

Biomarker Development

Review of Definitions: Prognostic marker

Independent of treatment May impact surveillance

Predictive marker Impacts type of treatment provided

Molecular Markers for Anti-VEGF

None identified and validated: Bevacizumab Aflibercept Regorafenib

Anti-EGFR Therapy Predictive: KRAS/NRAS Prognostic: BRAF

Current Molecular Markers

KRAS Proto-oncogene First globally utilized predictive marker for

the treatment of MCRC when considering anti-EGFR therapy

30%-50% of all patients MT (exon 2): codons 12, 13, 61, and

rarely 146 KRAS WT does = efficacy of therapy nor

does it indicate duration of response

Copyright © American Society of Clinical Oncology

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

Cetuximab and K-ras modulate signaling through the epidermal growth factor receptor (EGFR) pathway

BRAF MT Serine-threonine kinase belong to the RAF

family Mutation also leads to constitutive activation V600E accounts for 90% of mutations Found in < 10 % of all CRC patients Associated with hypermethylation of CpG island. Mutually exclusive with KRAS MT Prognostic but NOT predictive

All studies insufficiently powered to provide sufficient data to determine use of anti-EGFR therapy based on BRAF status.

NRAS Resembles Kras Oncogene < 5% of all mCRC Mutations in codons 12, 13, 61, 117 and

146 Usually codon 61

Mutually exclusive with KRAS

Front-line chemotherapy with anti-EGFR therapy

Update on PRIME Study Phase III

Douillard JY, et al. J Clin Oncol. 2010;28:4697-4705.

Patients• Previously untreated mCRC

• Fluorouracil-based adjuvant chemotherapy allowed if PD occurred ≥6 mo after completion; no oxaliplatin

• Tumor tissue from primary tumor or metastasis available for biomarker analysis

• ECOG PS 0-2

• N=1183Primary endpoint: PFS

Panitumumab 6.0 mg/kg q 2 wkFOLFOX4 q 2 wk

1:1 Randomization

FOLFOX4 q 2 wk

Distribution of mutations in mCRC

RAS wt~50%

KRAS mt (exon 2)

~40%

KRAS mt(non exon 2 KRAS mt) &

NRAS mt~10%

Rare KRAS MutationsNRAS Mutations

Douillard JY. ASCO 2013. Abstract 3620; Oliner KS. ASCO 2013. Abstract 3511.

PRIME Biomarker Analysis: Analysis of KRAS/NRAS and BRAF Mutations

RAS and BRAF Status FOLFOX4 Alone Panitumumab + FOLFOX4

KRAS exon 2 (codon 12/13) WTMT

331219

325221

WT KRAS exon 2 tumors tested for RAS and BRAF (n = 321) (n = 320)WT KRAS exon 2/MT other RAS, n (%) 57 (18) 51 (16)

KRAS exon 3 (codon 61), n (%)WTMT

Failure

306 (95)14 (4)1 (0)

308 (96)10 (3)2 (1)

KRAS exon 4 (codons 117/146), n (%)WTMT

Failure

296 (92)15 (5)10 (3)

288 (90)21 (7)11 (3)

NRAS exon 2 (codons 12/13), n (%)WTMT

Failure

307 (96)14 (4)0 (0)

308 (96)8 (3)4 (1)

NRAS exon 3 (codon 61), n (%)WTMT

Failure

305 (95)14 (4)2 (1)

305 (95)12 (4)3 (1)

NRAS exon 4 (codons 117/146), n (%)WTMT

Failure

313 (98)0 (0)8 (2)

316 (99)0 (0)4 (1)

BRAF exon 15 (codon 600), n (%)WTMT

Failure

280 (87)29 (9)12 (4)

286 (89)24 (8)10 (3)

Oliner J, et al. J Clin Oncol. 2013;31(Suppl): Abstract 3511. Oliner J, et al. Eur J Cancer. 2013;49(Suppl 2): Abstract 2275.

Revised PRIME Consort Diagram

Douillard et al: NEJM, 2013

PRIME: Progression-free survival in patients with (A) Original wild-type (WT) KRAS, (B) Updated All WT RAS, Overall survival in patients with (C)

Original WT KRAS and (D) All WT KRAS

Douillard J et al. JCO 2010;28:4697-4705; NEJM, 2013©2010 by American Society of Clinical Oncology

D

B

PFS: Wild-Type (WT) KRAS Exon 2 + mutant (MT) Other RAS

Oliner KS. ASCO 2013. Abstract 3511.

OS: Wild-Type (WT) KRAS Exon 2 + mutant (MT) Other RAS

Oliner KS. ASCO 2013. Abstract 3511.

PRIME: Summary and Clinical Implications

About 17% of patients with mCRC harbor mutations beyond KRAS exon 2 mutations

Excluding patients with RAS mutations identifies patients more likely to benefit from anti-EGFR therapy.

Practical interpretation: until an all-RAS test becomes available, EGFR monoclonal antibodies have the potential to be detrimental in patients who may harbor an unrecognized RAS mutation when administered with oxaliplatin-based chemotherapy regimens

Douillard JY. ASCO 2013. Abstract 3620; Oliner KS. ASCO 2013. Abstract 3511.

Treatment choice: Front line chemotherapy with anti-EGFR therapy

or anti-VEGF therapy?

PEAK: Randomized Phase II (KRAS WT)

FOLFOX/Pmab (N=142)

FOLFOX/Bev (N=143)

Median PFS (95% CI) 10.9 (9.4-13.0) 10.1 (9.0-12.6)

Median OS (95% CI) 34.2 (26.6-NR) 24.3 (21.0-29.2)

ORR (95% CI) 58 (49-66) 54 (45-62)]

Subsequent therapy:Anti EGFR

21% 38%

Anti-VEGF 40% 24%

Schwarzberg et al: JCO 2014

PEAK: Randomized Phase II (KRAS WT and rare RAS WT)

FOLFOX/Pmab (N=88)

FOLFOX/Bev (N=82)

Median PFS (95% CI) 13.0 (10.9-15.1) 9.5 (9.0-12.7)

Median OS (95% CI) 41.3 (28.8-41.3) 28.9 (23.9-31.3)

ORR (95% CI) 64 (52.7-73.6) 61 (49-71.2)

Subsequent therapy:Anti EGFR

22% 37%

Anti-VEGF 40% 33%

Schwarzberg et al: JCO 2014

FIRE-3 Phase III Study Design

Heinemann V. ASCO 2013. Abstract LBA3506.

Patients• mCRC

• KRAS wild-type

• ECOG PS 0-2

• 1st line therapy; prior adjuvant chemotherapy allowed if completed >6 mo before inclusion

• N=592 Primary Endpoint: Response Rate

FOLFIRI + Cetuximab(Cetuximab: 400 mg/m2 loading dose;

250 mg/m2 weekly)

1:1 Randomization

FOLFIRI + Bevacizumab(Bev: 5 mg/kg every 2 weeks)

FIRE-3: Overall Response Rate

Endpoint FOLFIRI + Cetuximab

FOLFIRI + Bevacizumab OR P Value

ORR, intent-to-treat (ITT) population (N=592)

62.0% 58.0% 1.18 (0.85-1.64) 0.183

Complete response 4.4% 1.4%

Partial response 57.6% 56.6%

Stable disease 17.5% 28.8%

Progressive disease 7.1% 5.4%

Not evaluable 13.1% 7.8%

ORR, Evaluable (N=526) 72.2% 63.1% 1.52(1.05-2.19) 0.017

Heinemann V. ASCO 2013. Abstract LBA3506.

FIRE-3: Progression Free Survival

Stintzing S. ASCO 2013. Abstract LBA3506

FIRE-3: Overall Survival

Heinemann V. ASCO 2013. Abstract LBA3506.

Consort FIRE-3 Diagram

N=592KRAS exon 2 wild-type

ITT population

N=407 (69%)RAS evaluable population

N=65 (16%)‘New’ RAS mutant

N=342RAS wild-type

N= 171 FOLFIRI +Cetuximab

N= 34FOLFIRI

Cetuximab

N= 171 FOLFIRI +

Bevacizumab

N= 31FOLFIRI +

Bevacizumab

N=752mCRC 1st-line

unselected patients

N=58FOLFIRI +Cetuximab

N=55FOLFIRI +

Bevacizumab

N=113KRAS exon 2 mutant

population*

KRAS unknown= 30No treatment= 13

No treatment KRAS mt = 4

Stinzing et al: ESMO, 2013

KRAS Wildtype Exon 2 Additional Subsets

?

? ?

EXON 1 EXON 2 EXON 3 EXON 4

EXON 2 EXON 3 EXON 4

KRAS

NRAS

12 13

12 13

61 146

59 61 117 146

wt

? ?

EXON 1

EXON 15EXON 11BRAF

600? ?

Heinemann V, et al. J Clin Oncol. 2013;31(Suppl): Abstract LBA3506.

Eventsn/N (%)

Median(months)

95% CI

― FOLFIRI + Cetuximab 91/171(53.2%)

33.1 24.5 – 39.4

― FOLFIRI + Bevacizumab 110/171(64.3%)

25.6 22.7 – 28.6

HR 0.70 (95% CI: 0.53 – 0.92)p (log-rank)= 0.011

FIRE-3: Overall survival RAS* all wild-type

0.012 24 36 48 60 72

months since start of treatment

171171

No. at risk

128127

7168

3926

209

61

0.75

1.0

0.50

0.25

0.0

Prob

abili

ty o

f sur

viva

l

Δ = 7.5 months

* KRAS and NRAS exon 2, 3 and 4 wild-typeStinzing et al: ESMO, 2013

FIRE-3 Update: Overall Survival by All-RAS Mutation Status

Study Population FOLFIRI + Cetuximab

FOLFIRI + Bevacizumab HR P

Value

ITT (N=592) 28.7 months 25.0 months 0.77 0.017

RAS WT (n=342) 33.1 months 25.6 months 0.70 0.011

RAS MT (n=65) 16.4 months 20.6 months 1.20 0.57

BRAF MT (n=48) 12.3 months 13.7 months 0.87 0.65

Stintzing S. European Cancer Conference 2013. Abstract LBA17.

FIRE-3: Summary and Clinical Implications

Current data limitations No central assessment of response OS data continues to mature Duration of second and subsequent lines of therapy

not reported Practical impact

EGFR antibodies added to FOLFIRI can be considered a viable option in first-line, KRAS wild-type mCRC

Next steps CALGB 80405 data (in 2014) may clarify results

Heinemann V. ASCO 2013. Abstract LBA3506.

Should all RAS WT patients receive anti-EGFR therapy

front-line?

New EPOC Study: Chemotherapy ± Cetuximab in Operable KRAS-WT mCRC

Original EPOC study showed 8% PFS benefit to addition of neoadjuvant FOLFOX to surgery in mCRC patients with operable liver metastases[1]

New EPOC study evaluated addition of cetuximab to standard neoadjuvant chemotherapy in mCRC[2]

Primary endpoint: PFS Secondary endpoints: OS, preop response, pathologic resection status, periop safety, QoL,

cost-effectiveness

Patients with resectable KRAS WT mCRC with liver mets

(N = 621)

Neoadjuvant Chemotherapy*(randomized n = 134;

primary analysis n = 116)

Neoadjuvant Chemotherapy* + Cetuximab

(randomized n = 137;N = 117)

1. Nordlinger G, et al. Lancet. 2008. 2. Primrose JN, et al. ASCO 2013. Abstract 3504.

*CAPOX, OxMdG, IrMdG

New EPOC: Neoadjuvant Chemotherapy ± Cetuximab in Operable KRAS-WT mCRC: PFS

Median PFS significantly worse with cetuximab: 14.1 months vs 20.5 months with chemotherapy alone

Study stopped at predefined futility analysis

Immature data, but more events unlikely to change result

Primrose JN, et al. ASCO 2013. Abstract 3504.

Prop

ortio

n pr

ogre

ssio

n fr

ee

1.00

0.75

0.50

0.25

0.00

0 6 12 18 24 30 36 42 48 54 60Time to progression or death (months)

HR: 1.49 (95% CI: 1.04-2.12); P = .030

Number at riskChemo alone

Chemo + Cetuximab 116

117

89

87

65

54

38

24

23

15

12

5

5

3

2

2

1

1

1

0

0

0

Chemo aloneChemo + cetuximab

Why did the new EPOCH study fail? KRAS is a predictive marker of potential benefit

for the use of EGFR inhibition. Cetuximab does not have a role in the adjuvant

setting N0147: FOLFOX +/- cetuximab failed to demonstrate

an improvement in DFS in stage III colon cancer 3-yr DFS: 74.6% vs 71.5% with the addition of

cetuximab (HR, 1.21; 95% CI, 0.98–1.49; P=.08) Is it the combination of FOLFOX and cetuximab?

Alberts et al: JAMA. Apr 4, 2012; 307(13): 1383–1393.

Upcoming: Liver-Only Trials

BOS-2 (EORTC 40091): Phase II KRAS WT Resectable Liver Mets

RANDOMIZE

FOLFOX

• First-line mCRC

• N=360

FOLFOX + bevacizumab

FOLFOX + panitumumab

Study amended: Wild-type KRAS tumors only

Primary Endpoint: PFS

http://www.clinicaltrials.gov/ct2/show/NCT01508000?term=BOS-2&rank=1

BOS -3 (EORTC-1207) Phase II/III Study Design (Pending)

http://www.clinicaltrials.gov/ct2/show/NCT01646554?term=BOS-2&rank=2

Patients• mCRC

• KRAS MT

• ECOG PS 0-1

• 1st line therapy; prior adjuvant chemotherapy allowed if completed >12 mo before inclusion

Primary endpoint: PFS

FOLFOX + Aflibercept(Aflibercept: 4 mg/m2)

1:1 Randomization

FOLFOX

CALGB/SWOG 80405: Results: ASCO 2014

RANDOMIZE

FOLFOX or FOLFIRI* + cetuximab

• First-line mCRC

• Amended accrual; N=2300 wild-type patients

FOLFOX or FOLFIRI* + cetuximab + bevacizumab

FOLFOX or FOLFIRI* + bevacizumab

Study amended: Wild-type KRAS tumors only

Primary endpoint: OS

SWOG 1406: BRAF MT mCRC

PI: S Kopetz

Conclusions: All RAS WT tumor types may provide more

benefit in OS if an anti-EGFR therapy is provided in the front-line setting.

Provision of anti-EGFR therapy in the setting of a RAS MT can be detrimental Many institutions utilize outside sites for tissue

processing Not all codons are identified Need a readily available panel with all RAS

mutations