1. Selection of Anti-EGFR Antibodies in the Treatment of MCRC (Abstracts # 3510 and 3511)
Tanios Bekaii-Saab, MD
The Ohio State University Comprehensive Cancer Center
Arthur James Cancer Hospital and Solove Research Institute

2. Potential Conflicts Research Grants Consultant/Speaker NCI/CTEP
Oncolytics Inc
Genentech
Roche
Pfizer
ENZON
Consultant/Speaker
BMS
Amgen
Lilly
Onyx
Array Biopharma

3. Anti-EGFR Antibodies in MCRC
Cetuximab
Panitumumab
Targets Extracellular Domain of EGFR
IgG1 chimeric mouse Mab
t1/2= 4.7 days
Targets Extracellular Domain of EGFR
IgG2 fully humanized Mab
t1/2= 7.5 days
Wheeler DL, et al Nat Rev Clin Oncol (9) :

4. Anti-EGFR Antibodies and KRAS mutations
Anti-EGFR Antibody
EGFR
WT KRAS
MT KRAS
79%
Others
Codon 12 ?
18%
~40%
MT BRAF
5-10%
Codon 13 3%
Codons 61,146 ,others
EGFR signaling Is mainly dependent on an intact KRAS pathway in CRC. In 40% of the patients, KRAS is mutated , leading to constitutive activation of the pathway and therefore will interfere withEGFR blockade. ……
Not all tumors with an intact KRAS pathway will respond to anti-EGFR blockade. There is the possibility that other mutations downstream from KRAS , such as BRAF ( 5-10%) of patients or in other parallel pathways may interfere with EGFR blockade.
Bekaii-Saab, T . Adapted from multiple sources: 1- Wheeler DL, et al Nat Rev Clin Oncol (9) : ;2- De Roock et al . Lancet Oncology, : ; 3- Frattini M , BJC ; ; 4- Di Nicolantonio F et al . Journal of Clin Oncol (35); ; 5- Loupakis F et al. BJC ; ;

5. KRAS status as a determinant of response to anti-EGFR antibodies
Initial retrospective analyses of MCRC trials suggested that patients with KRAS-mutated (MT) tumors will not benefit from EGFR inhibitors
Health Authorities in the US and EU recently indicated that patients with KRAS codon 12 or 13 MT tumors are not candidates for cetuximab or panitumumab
Allegra et al. J Clin Oncol. 2009;27(12):
De Rook et al. JAMA. 2010;304(16):

6. Anti-EGFR antibodies in First Line Treatment of MCRC
The first introduction of anti-EGFR antibodies to the treatment of MCRC were in the more refractory setting where they became part of the standard of care.
More recently, a number of prospective phase III randomized studies evaluated the role of adding anti-EGFR antibodies to chemotherapy in the first line treatment of MCRC.
Wheeler DL, et al Nat Rev Clin Oncol (9)

7. FOLF/XEL/OX + Cetuximab
Chemotherapy Regimens Containing Anti-EGFR Antibodies in First Line Treatment of mCRC From Phase III Studies
Trial
Cetuximab
Panitumumab
CRYSTAL1
(KRAS WT)
(N=350 vs 316)
COIN2
(N=367 vs 362)
NORDIC VII3
(N=185 vs 194)
PRIME 2034
(N=590 vs 593)
Treatment
FOLFIRI
FOLFIRI + Cetuximab
FOLF/XEL/OX
FOLF/XEL/OX + Cetuximab
Cont.
5-FU/FA/Ox
5FU/FA/Ox + Cetuximab
FOLFOX
FOLFOX + Panitumumab
OS (mos)
P value HR
20.0
23.5
0.0093
0.80
17.9
17.0
0.60
1.038
22.0
20.1
0.66
1.14
19.7
23.9
0.17
0.88
PFS (mos)
8.4
9.9
0.0012
0.70
8.6
0.959
8.7
7.9
1.07 10
0.01
ORR, %
39.7
57.3
<0.001 57 64
0.049 47 46
0.87 48
0.02
Emphasize that CRYSTAL was a retrospective study.
1. Van Cutsem, et al. J Clin Oncol ) pp Maughan, et al. J Clin Oncol. 2010;28:15s(suppl; abstr 3502). 3. Tveit, et al. ASCO GI (abstr 365). 4. Douillard, et al. ASCO 2011 ( abstr 3510). 7

8. Q: How to Shape the Landscape of First Line Treatment of mCRC?
A: Follow the data.
Not That Simple !

9. Selection of Biologics in First Line Treatment of Patients with KRAS WT mCRC
Biologics play a prominent role in the first line treatment of mCRC when added to chemotherapy.
Which biologic?
Today’s standard is Bevacizumab ( at least in the US) for most patients
EGFRI vs. VEGFI
Comparative Data needed for EGFRI vs. VEGFI including in the subgroup of patients with disease confined to the liver
CALGB/SWOG 80405
We are lacking predictors for VEGFI while treatment with EGFRI seems to be getting better refined.

10. Selection of Anti-EGFR Antibodies in First Line Treatment of Patients with KRAS WT mCRC
In first line treatment, results of PIII studies suggest that panitumumab synergizes with FOLFOX whereby cetuximab may not?
Differences between antibodies? Differential synergism with the 2 antibodies?
Study design/schedule issues?
Both anti-EGFR antibodies seem to exert a more consistent differential synergism with irinotecan based regimens vs. oxaliplatin ones across lines of therapy ( CRYSTAL , 181, BOND… )
In KRAS MT CRC, both anti-EGFR antibodies exert a negative interaction with oxaliplatin but not with irinotecan.
Implications on future metastatic studies  Chemotherapy backbone matters!
Implications on adjuvant studies?

11. Centralized KRAS analysis
NO147: Adjuvant mFOLFOX6/FOLFIRI ± Cetuximab (KRAS WT and Mutant, Resected Stage III Colon Cancer)
mFOLFOX6
(n=902)
REGISTER
mFOLFOX6 + cetuximab
(n=945)
Adjuvant therapy per primary oncologist
Report therapy given
Annual status through year 8
Stage III colon cancer
(N=3768: FOLFOX/Cet)
(N=146: FOLFIRI/Cet) P R E
G I S T
KRAS mutant
KRAS WT
Centralized KRAS analysis
FOLFIRI (12 cycles)
(n=106)
FOLFIRI + cetuximab
(12 cycles)
(n=40)
RANDOMIZE X
Primary endpoint: DFS
Secondary endpoints: OS, safety
Huang, et al. ASCO GI (abstr 363).

12. Disease-Free Survival
NO147 FOLFIRI ± Cetuximab in KRAS WT Patients with Stage III Colon Cancer :
A Missed Opportunity?
Disease-Free Survival
(n=95)
Overall Survival
(n=95)
FOLFIRI
FOLFIRI
FOLFIRI + cetuximab
FOLFIRI + cetuximab
% Alive and Disease Free
100 90 80 70 60 50 40 30 20 10
Time, Months
% Alive
100 90 80 70 60 50 40 30 20 10
Time, Months
Arm
3-Year Rates, % (95% CI)
HR (95% CI)
P Value
FOLFIRI (N=69)
(60-82)
( )
0.04
FOLFIRI + cetuximab (N=26)
(83-100)
Arm
3-Year Rates, % (95% CI)
HR (95% CI)
P Value
FOLFIRI (N=69)
(77-94)
( )
0.13
FOLFIRI + cetuximab (N=26)
(82-100)
Huang, et al. ASCO GI (abstr 363).

13. Selection of Anti-EGFR Antibodies: Are all KRAS Mutations in Colorectal Cancer Created Equal ?

14. Association of Various KRAS Mutations with Outcome in Patients with Colorectal Cancer
Andreyev HJN. BJC: 2001 ; 85(5),

15. Association of Various KRAS Mutations with Outcome in Patients with Chemorefractory Colorectal Cancer treated with Cetuximab
Comparisons include any cetuximab therapy (with or without chemotherapy) vs no cetuximab, cetuximab monotherapy vs no cetuximab, and a sensitivity analysis including only those randomized from the CO.17 trial (cetuximab monotherapy vs no cetuximab). P values for interaction (adjusted for predefined prognostic factors) indicate capacity of biomarker to differentiate outcomes between KRAS mutation status subgroups. CI indicates confidence interval; NA, not enough data to estimate. Pooled Data of 579 chemorefractory patients treated with cetuximab between
Studies included: CO.17, BOND, MABEL, EMR202600,EVEREST, BABEL and SALVAGE
De Roock, W. et al. JAMA 2010;304:
Copyright restrictions may apply.

16. In Vitro and In Vivo Effects of the p.G13D Mutation
Effect of Cetuximab on Cellular Proliferation in Isogenic Cell Lines
Proliferation Assay on Isogenic Cell lines
Effect of Cetuximab on Growth of Tumor
De Roock, W. et al. JAMA 2010;304: e-suppl.

17. Influence of KRAS G13D mutations on outcome in pts with mCRC treated with First Line Chemotherapy +/- cetuximab
Tejpar et al . Abs 3511 ASCO 2011.

18. KRAS G13D and BRAF mutations are prognostic in MCRC
CRYSTAL (FOLFIRI Only): OS for patients according to tumor KRAS mutation status.
CRYSTAL : OS for patients with KRAS WT disease according to tumor BRAF mutation status.
Kaplan-Meier plots for overall survival time according to treatment arm for (A) the intention-to-treat population; (B) patients in the KRAS population whose tumors were wild-type or mutant for KRAS; and (C) patients with KRAS wild-type disease according to tumor BRAF mutation status. FOLFIRI, irinotecan, leucovorin and fluorouracil; HR, hazard ratio; MT, mutant; WT, wild-type.
Tejpar et al . Abs 3511 ASCO 2011.
Van Cutsem E et al. JCO 2011;29:
©2011 by American Society of Clinical Oncology

19. Predictive Biomarkers For the Use of Anti-EGFR Antibodies in mCRC
Anti-EGFR Antibody
EGFR
WT KRAS
MT KRAS
79%
- PTEN LOE
- NRAS MT
- PIK3CA ex 20 MT
Other
Codon 12
18%
~40%
MT BRAF
5-10%
Codon 13 3%
Codons 61,146 ,others
Bekaii-Saab, T. Adapted from multiple sources: 1- Wheeler DL, et al Nat Rev Clin Oncol (9) : ;2- De Roock et al . Lancet Oncology, : ; 3- Frattini M , BJC ; ; 4- Di Nicolantonio F et al . Journal of Clin Oncol (35); ;5- Loupakis F et al. BJC ; ; 6- Tran B . Cancer 2011 ; 1-10.

20. The EGFR Signaling Network is Large and Complex20

21. Complex Genetic structures in subsets of CRC
Gene name
Pathway
Fold
change
P.Adj
AQP5
Aquaporin 5
target of ESR1; promotes proliferation and inhibits apoptosis in chronic myelogenous leukemia; interacts with the MAPK and Rb pathway
5,5
9,7E-21
CTSE
cathepsin E
is found in highest concentration in the surface of epithelial mucus-producing cells of the stomach. Found in more than half of gastric cancers.
4,8
5,43E-11
SOX8
SRY (sex determining region Y)-box 8
Wnt/beta-catenin signaling
2,6
0,000217
REG4
regenerating islet-derived family, member 4
activator of the EGFR in CRC, involved in gastric and pancreatic cancers
3,7
1,68E-07
PIWIL1
piwi-like 1
intrinsic regulator of the self-renewal capacity of germline and hematopoietic stem cells.
2,5
9,43E-05
AXIN2
Axin 2
-2,1
5,65E-06
CDX2
caudal type homeobox 2
-2,3
1,16E-10
HSF5
heat shock transcription factor family member 5
-3,1
5,79E-10
TFCP2L1
transcription factor CP2-like 1
4,5E-08
GGH
gamma-glutamyl hydrolase
associated with CIMP+ in colon cancer
-3,0
8,54E-08
RNF43
ring finger protein 43
ubiquitin ligase that promotes cell growth and is upregulated in colon cancer
-2,2
1,35E-07
PTPRO
protein tyrosine phosphatase, receptor type, O
Growth-suppressor; epithelial adherens junctions
-3,2
SPINK1
serine peptidase inhibitor, Kazal type 1
interacting with CTSB
-2,9
9,73E-06
SATB2
SATB homeobox 2
promotes growth and metastasis in breast cancer
-2,5
1,17E-05
DPEP1
-2,4
2,76E-05
TNNC2
9,21E-05
PCLO
0,00017
Kras variant sub-populations in WT groups
KRAS MT are not associated with a single homogenous gene expression patterns
BRAF MT have a characteristic gene expression pattern defined by MS status.
Tejpar , S et al . ASCO 2010 Abs 3505

22. Conclusions and Future Directions
KRAS G13D and BRAF mutations likely have an adverse prognostic effect in mCRC
Modest benefit with the addition of anti-EGFR antibodies
Cost/Benefit question may be difficult to address in a randomized trial
Prospective validation of results is needed
Future studies with anti-EGFR antibodies should include and stratify for KRAS G13D and BRAF mutations
KRAS G12 mutation is predictive of lack of response to anti-EGFR antibodies
KRAS G12V likely has no prognostic value in mCRC
It is likely that complex genetic structures exist in subsets of CRC.
Therapeutic Implications

23. Take Home Messages For Everyday Clinical Practice
Anti-EGFR antibodies improve the efficacy of chemotherapy in the first line treatment of patients with KRAS WT mCRC.
There still is a need identify possible superiority of one biologic vs. the other (EGFRI vs. VEFGI) including in mCRC confined to the liver.
Outside the confines of a clinical study, testing for KRAS G13D, BRAF and other mutations other than KRAS 12 is not recommended given the questionable lack of their predictive value for the use of Anti-EGFR antibodies in mCRC
Prospective validation including cost-benefit analysis needs evaluated.