593treatment effects” can result in guidelines that promote overtreatment as well as
undertreatment, and recommended estimation of treatment effects after stratifying
trial participants according to baseline risk. Better stratifi cation of persons by dis-
ease stage, or baseline risk of relevant outcomes, is more likely to identify those
who will benefi t and those who will be harmed by an intervention, leading to the
development of appropriate diagnostic and treatment thresholds, ultimately reduc-
ing overdiagnosis as well as overtreatment (Moynihan et al. 2014 ). This approach is
in line with personalized medicine. Pharmacogenomic approach to clinical trials is
discussed in Chapter and other measures to improve clinical trials are discussed in
the following sections.
Use of Bayesian Approach in Biomarker-Based Clinical Trials
Innovative clinical trial designs are needed to address the diffi culties and issues in
the development and validation of biomarker-based personalized therapies. A new
clinical trial design that captures the strengths of the frequentist and Bayesian
approaches has been proposed to address some of these issues (Lai et al. 2012 ).
There are advantages of using likelihood inference and interim analysis to meet the
challenges in the sample size needed and in the constantly evolving biomarker land-
scape and genomic and proteomic technologies.
The statistical method used nearly exclusively to design and monitor clinical tri-
als today, a method called frequentist or Neyman-Pearson (for the statisticians who
advocated its use), is so narrowly focused and rigorous in its requirements that it
limits innovation and learning. A solution is to adopt a system called the Bayesian
method, a statistical approach more in line with how science works. The main dif-
ference between the Bayesian approach and the frequentist approach to clinical tri-
als has to do with how each method deals with uncertainty, an inescapable component
of any clinical trial. Unlike frequentist methods, Bayesian methods assign anything
unknown a probability using information from previous experiments. In other
words, Bayesian methods make use of the results of previous experiments, whereas
frequentist approaches assume we have no prior results. This approach is being put
to the test at M. D. Anderson Cancer Center (Houston, TX), where >100 cancer-
related phase I and II clinical trials are being planned or carried out using the
Bayesian approach. The Bayesian approach is better for doctors, patients who
participate in clinical trials and for patients who are waiting for new treatments to
become available. Physicians want to be able to design trials to look at multiple
potential treatment combinations and use biomarkers to determine who is respond-
ing to what medication. They would like to treat that patient optimally depending on
the patient’s disease characteristics. If interim results indicate that patients with a
certain genetic makeup respond better to a specifi c treatment, it is possible to recruit
more of those patients to that arm of the study without compromising the overall
conclusions. Use of the Bayesian approach may make it possible to reduce the num-
ber of patients required for a trial by as much as 30 %, thereby reducing the risk to
patients and the cost and time required to develop therapeutic strategies.
Role of Pharmaceutical Industry