Data augmentation based on waterfall plots to increase value of response data generated by small single arm Phase II trials.

Waterfall plots have been increasingly used to visualize tumor response measurements in Phase II clinical trials. Despite the growing popularity of waterfall plots, quantitative summaries and distribution features of the data indicating antitumor activities are typically not reported. Statistical summaries from the raw and augmented data may provide valuable information for understanding such features. This issue has not been discussed adequately in the literature or fully recognized within the oncology community. In this article, we propose to augment the data using a statistical distribution system. Summary statistics of the data set corresponding to waterfall plot can be calculated using the original sample of the tumor changes or the augmentation sample, which may lead to additional insights into the treatment effect. We demonstrate the proposed method in numerical studies and in a Phase II clinical trial investigating the efficacy of a treatment for ovarian carcinoma. We recommend the proposed statistical analyses for making inferences in addition to the waterfall plot visualization.