Re-formulating Gehan's design as a flexible two-stage single-arm trial

Area of Science:

• Clinical Trial Design
• Biostatistics
• Oncology Research

Background:

• Gehan's two-stage design was a historical standard for phase II oncology trials.
• It is less used today due to the inability to formally test treatment efficacy and control error rates.

Purpose of the Study:

• To incorporate hypothesis testing into Gehan's design using flexible two-stage trial methodology.
• To optimize the hypothesis test for maximum power.
• To adjust second-stage sample sizes for desired operating characteristics.

Main Methods:

• Application of recent methodology for flexible two-stage single-arm trials.
• Optimization of hypothesis testing within Gehan's framework.
• Comparison of modified Gehan designs with Simon's designs using clinical trial examples.

Main Results:

• Modified Gehan designs can formally test treatment efficacy, addressing a key limitation.
• Control parameters can be adjusted to resolve power issues in Gehan's original designs.
• Operating characteristics of modified Gehan designs resemble those of Simon designs.

Conclusions:

• Modified Gehan designs offer an alternative to Simon designs, with potential utility when precise estimation of treatment response rate is the primary goal.
• Careful selection of second-stage sample sizes is crucial for optimal performance.
• The applicability of modified Gehan designs may be limited to specific trial settings.