Waterfall plot analysis of XELOX or XELIRI with cetuximab or bevacizumab in pts with advanced colorectal cancer (ACRC). Combined analysis of two randomized 1st line phase II trials if the AIO CRC study group. Dirk Arnold1, Axel Hinke2, Anke Reinacher-Schick3, Wolff Schmiegel3, Ullrich Graeven4, Stefan Kubicka5, Ludwig Fischer von Weikersthal6, Nicolas Moosmann7, Hans-Joachim Schmoll1, Volker Heinemann7 1Martin Luther University, Halle; 2WiSP, Langenfeld; 3Ruhr University, Bochum; 4Maria Hilf Hospital, Mönchengladbach, 5Medizinische Hochschule, Hannover; 6Klinikum St. Marien, Amberg; 7Ludwig Maximilian University, München; all: Germany Working Group for Medical Oncology from the German Cancer Society Gastrointestinal Tumor Study Group

Introduction The Response Evaluation Criteria in Solid Tumors (RECIST) or World Health Organization (WHO) criteria can be used to assess the treatment response rate (RR) in patients with advanced colorectal cancer (ACRC). Owing to the methodology used, RR measures the percentage of patients with relevant tumor shrinkage rather than the magnitude of response or the time until maximal response. Both of these parameters could be relevant for ACRC treatment strategies. Waterfall plots have commonly been used to capture the anti-tumor efficacy of biologic agents that mainly exhibit a cytostatic effect. Thus far, only one waterfall analysis has been conducted to investigate the use of conventional chemotherapy in patients with ACRC.1 In order to assess the activity of different compounds used in the treatment of ACRC, waterfall plot analyses were performed on two similarly designed, randomized, first-line, phase II trials: AIO KRK 0104: XELOX-cetuximab vs. XELIRI-cetuximab) (Fischer von Weikersthal et al., ESMO 20062; update ASCO 2008: #4033 ) AIO KRK 0604: XELOX-bevacizumab vs. XELIRI-bevacizumab (Schmiegel et al., ASCO 20073; Reinacher-Schick et al., update ASCO 2008: #4030)

Method of the analysis Using RECIST, the percentage change from baseline in tumor volume was evaluated when “best response” to treatment was obtained. A time window of assessment from 6 to 21 weeks (wks) was thereby used throughout the analysis. Average reduction in tumor burden (ARTB) was calculated as difference in waterfall area under curve (AUC) divided by the number of pts., capturing the average reduction in tumor burden. Median reduction in tumor burden (MRTB) captures median tumor size regression from baseline. From the 4 treatment arms, pooled 2x2 analysis was performed to compare XELOX vs. XELIRI (independent from biologic agent) bevacizumab (B) vs. cetuximab (C) (independent from chemotherapy backbone).

Patient population Data were available from eligible patients with measurable disease and at least one restaging (taken at “best response”): Pts. (total) Pts. herein % of all pts. AIO KRK 0104: XELOX-cetuximab vs. XELIRI-cetuximab 185 92 93 122 56 66 69 AIO KRK 0604: XELOX-bevacizumab vs. XELIRI-bevacizumab 255 127 128 199 100 99 78 total 440 321 73

Combined analysis - I Best response XELOX arms N=156 XELIRI arms N=165 (compared with baseline) XELOX arms N=156 XELIRI arms N=165 Bevacizumab N=199 Cetuximab N=122 Tumor growth (% of pts) No Change (% of pts) Tumor shrinkage (% of pts) 5 90 6 7 87 89 MRTB (%) 33 31 30 35 ARTB (%) 34.7 31.2 29.2 38.9 p (Wilcoxon Mann Whitney Test) 0.29 0.009 MRTB = median reduction in tumor burden ARTB = avarage reduction in tumor burden

Combined analysis - II 10 20 30 40 50 60 70 80 90 100 XELOX XELIRI with Bevacizumab with Cetuximab Tm Growth No Change Tm Shrinkage ARTB % of pts. (at best response) / % from baseline (ARTB) p=0.29 p=0.009 Wilcoxon Mann Whitney Test

Waterfall plot analysis of the treatment arms CIOX / XELOX + Cetuximab: Best Response 100 n = 56 50 AIO 0104: XELOX-cetuximab % change -50 -100 -150

Waterfall plot analysis of the treatment arms CIOX / XELIRI + Cetuximab: Best Response 100 n = 66 50 AIO 0104: XELIRI-cetuximab % change -50 -100 -150

Waterfall plot analysis of the treatment arms KRK 0604 / XELOX + Bevacizumab: Best Response 100 n = 100 50 AIO 0604: XELOX-bevacizumab % change -50 -100 -150

Waterfall plot analysis of the treatment arms KRK 0604 / XELIRI + Bevacizumab: Best Response 100 n = 99 50 AIO 0604: XELIRI-bevacizumab % change -50 -100 -150

Conclusion Waterfall plot analysis was successfully used to evaluate the results of the AIO KRK 0104 and the AIO KRK 0604 clinical trials. Waterfall analyses could be used to examine the results of other CRC trials using chemotherapy and targeted agents. Additional information on the rates of tumor reduction may be obtained by ARTB and MRTB. Our analysis suggests a larger degree of benefit for cetuximab containing combinations. However, the results should be interpreted with caution due to the limited sample sizes and the retrospective and unpreplanned character of the analysis. ARTB and MRTB should be validated in future trials and in relation to parameters like secondary metastasis resection, but also to clinically proven time-to-event-endpoints, like progression free survival and overall survival.