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Published on: October 31, 2012
A 2-stage phase II design with direct assignment option in stage II for initial marker validation
Ming-Wen An1, Sumithra J Mandrekar, Daniel J Sargent
1Department of Mathematics, Vassar College, Poughkeepsie, New York, NY, USA. mian@vassar.edu
Summary
This study introduces a novel two-stage phase II clinical trial design for biomarker-directed therapies. The proposed design balances randomization with direct assignment, offering an efficient approach for evaluating targeted treatments in marker-positive patients.
Area of Science:
- Clinical Trial Design
- Biomarker-Directed Therapies
- Phase II Clinical Trials
Background:
- Biomarkers are essential for identifying patient populations likely to respond to targeted therapies.
- Existing prospective designs for biomarker-directed therapy vary in study population and randomization schemes.
- There is a need for flexible trial designs that accommodate early efficacy signals while maintaining statistical rigor.
Purpose of the Study:
- To propose a novel two-stage phase II clinical trial design for biomarker-directed therapy.
- To incorporate an option for direct assignment in the second stage for marker-positive patients.
- To evaluate the statistical properties of the proposed design through simulation.
Main Methods:
- A two-stage phase II design was proposed, with stage I involving equal randomization to experimental treatment or control for marker-positive patients.
- Stage II allows for direct assignment to the experimental treatment.
- Simulations were conducted to compare the proposed design with a balanced randomized two-stage design, assessing power and type I error rates.
- Sensitivity analyses examined the impact of timing of stage I analysis, population shifts, and unbalanced randomization.
Main Results:
- The proposed design demonstrated minimal loss in statistical power (<1.8%) and a slight increase in type I error rate (<2.1%) compared to a balanced randomized design.
- The maximum increase in type I error rate under population shift conditions ranged from 3.1% to 5%.
- Loss in power due to the timing of stage I analysis was less than 1.2%.
Conclusions:
- The proposed two-stage phase II design offers desirable statistical properties and practical appeal for biomarker-directed therapies.
- The direct assignment option in stage II provides an "extended confirmation phase" as an alternative to early trial cessation.
- This design facilitates efficient evaluation of targeted treatments in marker-positive patient cohorts.
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