A Randomized Phase II Study of Gemcitabine Plus Oxaliplatin (GEMOX) With or Without Cetuximab in Locally Advanced and Metastatic Biliary Tract Cancer (BTC)

It is considered realistic, that within 18 months 120 patients can be included in the participating centers. Based on the previous publications an objective response rate (ORR) of 20% is expected in the GEMOX arm (Arm B). When the sample size of evaluable patients is between 110 and 120 evaluable patients (ie. 55 to 60 patients per treatment arm), then a two-sided 95% confidence interval (CI) for the difference between an arm B response rate PB, of 20% and an arm A response rate PA of 30%, 35% or 40% based on the large sample normal approximation will have a width between 15.4% and 16.7%. We assume an objective response rate of 30% for Arm A, then a two-sided 95% confidence interval (CI) for the difference between an arm B response rate PB, of 20% and an arm A response rate PA of 30% will have a width ±15.4% when the sample size of evaluable patients is 120 (i.e., 60 patients per treatment arm).