Better Decision Making in Drug Development Through Adoption of Formal Prior Elicitation

TL;DR

This paper discusses how GSK integrates formal expert elicitation methods, specifically the SHELF framework, into drug development to improve decision making, transparency, and robustness of prior distributions in Bayesian analyses.

Contribution

It presents a structured approach and real-world case studies demonstrating the integration of prior elicitation within a large pharmaceutical company's decision processes.

Findings

Elicitation provides a quantitative basis for decision making.

It enhances transparency and understanding of risks.

Supports better portfolio and project decisions.

Abstract

With the continued increase in the use of Bayesian methods in drug development, there is a need for statisticians to have tools to develop robust and defensible informative prior distributions. Whilst relevant empirical data should, where possible, provide the basis for such priors, it is often the case that limitations in data and/or our understanding may preclude direct construction of a data-based prior. Formal expert elicitation methods are a key technique that can be used to determine priors in these situations. Within GlaxoSmithKline (GSK), we have adopted a structured approach to prior elicitation based on the SHELF elicitation framework, and routinely use this in conjunction with calculation of probability of success (assurance) of the next study(s) to inform internal decision making at key project milestones. The aim of this paper is to share our experiences of embedding the use of prior elicitation within a large pharmaceutical company, highlighting both the benefits and challenges of prior elicitation through a series of case studies. We have found that putting team beliefs into the shape of a quantitative probability distribution provides a firm anchor for all internal decision making, enabling teams to provide investment boards with formally appropriate estimates of the probability of trial success as well as robust plans for interim decision rules where appropriate. As an added benefit, the elicitation process provides transparency about the beliefs and risks of the potential medicine, ultimately enabling better portfolio and company-wide decision making.