Eric Van Cutsem*, I. Lang, G. Folprecht, M. Nowacki , S. Cascinu, I. Shchepotin , J. Maurel,

1. Cetuximab plus FOLFIRI in the treatment of metastatic colorectal cancer: the influence of KRAS and BRAF biomarkers on outcome: updated data from the CRYSTAL trial Eric Van Cutsem*, I. Lang, G. Folprecht, M. Nowacki, S. Cascinu, I. Shchepotin, J. Maurel, D. Cunningham, P. Rougier, I. Celik, C.H. Köhne *University Hospital Gasthuisberg, Leuven, Belgium

2. Background: The CRYSTAL trial • KRAS wild-type mCRC patients treated 1st-line with cetuximab plus FOLFIRI compared with FOLFIRI alone experienced • Reduced risk of disease progression (Hazard Ratio, 0.68)1 • Increased chance of tumor response (59% vs 43%, p=0.0025)2 • In this final analysis we report • Increased follow-up time • Increased population of evaluable tumors for KRAS and BRAF mutations • The impact of BRAF mutation status on cetuximab efficacy in patients with KRAS wild-type tumors 1Van Cutsem E, et al. N Engl J Med 2009;360:1408-17; 2 Van Cutsem E, et al. J ClinOncol 2008;26: (suppl; abstr 2)

3. The CRYSTAL study Treatment until progression, symptomatic deterioration or unacceptable toxicity • Endpoints: • Primary- PFS time • Secondary- OS time, best overall response (OR) rate and safety • Retrospective subgroup analyses: • OS, PFS and OR by KRAS mutation status ECOG PS, Eastern Cooperative Oncology Group performance status; 5-FU, 5 fluorouracil; LV, leucovorin

4. Background: BRAF • Serine-threonine kinase BRAF is a direct downstream effector of KRAS • BRAF gene mutations have been detected in 8% of colon cancers (stage II/III – PETACC-3)1 • BRAF mutation status has been suggested to be predictive of cetuximab efficacy in pretreated patients with mCRC2,3 1Roth A, et al. J Clin Oncol 2010; 28:466-74; 2Di Nicolantonio F, et al. J Clin Oncol 2008;26:5705-12; 3Tejpar S et al on behalf of EU consortium, ECCO/ESMO, 2009

5. KRAS/BRAF evaluable population 540/1198 subjects (45% of ITT)1: KRAS evaluable population 1063 (89%) subjects: updated KRAS evaluable population 666 (63%) KRAS wild-type 625 (59%) KRAS wild-type/BRAF evaluable KRAS wild-type/BRAF wild-type 566/625 (91%) KRAS wild-type/BRAF mutant 59/625 (9%) • Sample numbers for KRAS and BRAF mutation status were increased using DNA extracted from tumor from paraffin blocks or formalin fixed paraffin embedded slide mounted sections prepared to evaluate tumor EGFR expression • KRAS (codons 12/13) and BRAF (V600E) mutations were detected using a PCR clamping and melting curve technique • BRAF mutations were detected in a total of 60/1000 (6%) evaluable samples,1 patient was also KRAS mutant 1Van Cutsem E, et al. N Engl J Med 2009;360:1408-17

6. Baseline characteristics according to tumor KRAS/BRAF mutation status ECOG PS, Eastern Cooperative Group performance status; mt, mutant; wt, wild-type

7. PFS in patients with KRAS wild-type tumors 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 4 8 12 16 20 Probability of PFS Cetuximab + FOLFIRI FOLFIRI Time (months) Number of patients 227 128 40 8 1 Cetuximab + FOLFIRI 316 FOLFIRI 350 237 111 22 4 0 CI, confidence interval; HR, hazard ratio; PFS, progression-free survival

8. PFS by subgroups in KRAS wild-type patients 0.3 0.4 0.5 1 2 3 4 HR and 95% CI Benefit under cetuximab No benefit under cetuximab Group A,cetuximab + FOLFIRI; Group B, FOLFIRI CI, confidence interval; ECOG PS, Eastern Cooperative Group performance status; HR, hazard ratio; LDH, lactate dehydrogenase; PFS, progression-free survival

9. OS in patients with KRAS wild-type tumors 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 6 12 18 24 30 36 42 48 54 • Median follow up was 46 months Probability of overallsurvival Cetuximab + FOLFIRI FOLFIRI Time (months) Number of patients 316 237 198 144 108 82 65 21 4 Cetuximab + FOLFIRI 281 350 311 246 179 132 92 64 48 18 FOLFIRI 2 CI, confidence interval; HR, hazard ratio; OS, overall survival

10. OS by subgroups in KRAS wild-type patients 0.3 0.4 0.5 1 2 3 4 HR and 95% CI No benefit under cetuximab Benefit under cetuximab Group A,cetuximab + FOLFIRI; Group B, FOLFIRI CI, confidence interval; ECOG PS, Eastern Cooperative Group performance status; HR, hazard ratio; LDH, lactate dehydrogenase; OS, overall survival

11. Response in patients with KRAS wild-typetumors aCochran-Mantel-Haenszel test CI, confidence interval; OR, best overall response

12. Tumor regression according to treatment in patients with KRAS wild-type tumors 100 80 60 40 20 0 -20 -40 -60 -80 -100 Cetuximab + FOLFIRI, n=316* FOLFIRI, n=350** Change in lesion (%) *Data for 16 patients were missing; **Data for 21 patients were missing • For patients receiving cetuximab + FOLFIRI compared with FOLFIRI alone, the mean difference • in the best % change of the lesion (based on WHO criteria) was 13.9%

13. Clinical efficacy in KRAS wild-typetumors by BRAF mutation status aStratified log-rank test; bCochran-Mantel-Haenszel test CI, confidence interval; OR, best overall response; OS, overall survival; PFS, progression-free survival; mo, months; mt, mutant; wt, wild-type

14. Conclusions: KRAS in the CRYSTAL trial • This final analysis shows for the first time in a randomized study that the addition of a targeted agent (cetuximab) to FOLFIRI in the 1st-line treatment of patients with metastatic colorectal cancer with KRAS wild-type tumors significantly improved OS compared to FOLFIRI alone • This final analysis confirms KRAS tumormutation status to be a predictive factor across all efficacy endpoints examined for cetuximab in combination with FOLFIRI

15. Conclusions: BRAF in the CRYSTAL trial • The analysis suggests BRAF tumor mutation to be a poor prognostic factor in 1st-line mCRC • BRAF mutation status does not appear to be a strong predictive biomarker for the addition of cetuximab to FOLFIRI in 1st-line treatment of mCRC

16. Acknowledgements The authors would like to thank patients, investigators, co-investigators and the study teams at each of the participating centers and at Merck KGaA Darmstadt, Germany