A decision rule for sequential monitoring of clinical trials with a primary and supportive outcome.

Background: Many clinical trials have multiple outcomes. Formal interim monitoring guidelines that take account of multiple outcomes can be useful to Data Monitoring Committees (DMC). Previous research has focused on marginal criteria that control the overall type I error for bivariate endpoints corresponding to efficacy and safety.

Estimation of cancer drug potencies and relative potencies from in vitro data.

A method is proposed for the estimation of drug or toxicity potencies using in vitro data. A typical experiment in cancer research is presented where cells from a tumor-derived cell line were deposited as fixed volumes in 12-well cell culture plates. After waiting for 72 hours (for further growth), the wells were exposed to different concentrations of a drug and, at the end of the experiment, the numbers of surviving cells were counted.

Design and analysis of in vitro experiments for combination chemotherapy.

A method is proposed for the evaluation of in vitro experiments for combination chemotherapy, a new and growing area of cancer research. We first describe and review a popular graphical device called an isobologram. We then propose a statistical framework, a simple experimental design, and a statistical test for use with this widely accepted methodology.

Quality control and the identification of vaccine responders using ELISA-derived antibody data.

First vaccines are traditionally licensed after showing favourable results from phase III efficacy trials. Subsequent competing vaccines, however, have been licensed primarily on the basis of immunogenicity data rather than clinical efficacy. Focusing on pneumococcal vaccines where optical densities are measured and serum antibody concentrations are 'estimated' (from a statistical model) using an immunoglobulin (IgG) enzyme-linked immunosorbent assay (ELISA), the focus of this paper will centre on two highly related issues: the determination of an upper limit for quality control used in the assay methodology (let us call it the maximum tolerated limit or MTL) and the identification of vaccine responders.

Evaluation of sampling strategies for modeling survival of uveal malignant melanoma.

Purpose: To evaluate sampling strategies used to estimate survival after uveal malignant melanoma that exclude some patients who would be censored from the analysis.

Methods: Simulation was performed on a population-based data set of 133 patients who had an eye enucleated because of uveal melanoma. One thousand bootstrap samples of 80 patients were drawn, without replacement, according to three sampling strategies: a random draw (conventional strategy), a draw limited to patients who died of the tumor or survived at least 10 years without metastasis ("late-censoring" strategy), and a draw modified so that 40 patients died of melanoma and others survived at least 10 years without metastasis ("fifty-fifty" strategy).