Improved Design for Clinical Trials & Multiple Agents

#B185 An Improved Design for Clinical Trials Evaluating Multiple Agents.

Christine E. McLaren,1 Vernon M. Chinchilli,2 Jennifer J. Roan,3 Frank L. Meyskens.4

University of California, Irvine,1 Irvine, CA, The Pennsylvania State University,2 Hershey, PA, Minitab, Inc.,3 State College, PA, Chao Family Comprehensive Cancer Center,4 Orange, CA.

For clinical trials that intend to answer multiple questions, new designs are needed to achieve results with fewer patients and less expense.

Adenomatous polyps are precursors to colorectal cancer, the fourth most common incident cancer in the United States. We propose a 2x2 balanced factorial design to test whether a combination of agents, difluoromethylornithine and sulindac, is better than the individual treatments or placebo with regard to reducing the proportion of recurrent adenomas.

For statistical assessment, the Cochran-Armitage test of trend can be used to compare the proportion of patients developing at least one adenoma between placebo and treatment groups.

Mehta et al considered a one-sided test of the null hypothesis of equal proportions in treatment groups against an ordered alternative of increasing proportions across treatment groups (Biometrics 54, 1998).

For the two-sided alternative, called the simple-loop alternative, we derived a pair of two-sided tests and a method for power and sample size calculations.

We compared this test with alternative tests for a factorial design under comparable assumptions.

The proposed design to study adenoma development, an intermediate marker for cancer incidence, achieves a reduction in sample size of over 30% and should lead to a significant reduction in the cost of the clinical trial.

For the study of experimental markers, we suggest the use of this experimental design to achieve economy in terms of patients and monetary expense.

Frontiers in Cancer Prevention Research, 2003 AACR

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