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Single arm two-stage studies: Improved designs for molecularly targeted agents
1Centre for Statistics in Medicine (CSM), Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, UK.
Abstract:
Mechanistic understanding of cancers and their potential interactions with molecularly targeted agents is driving the need for stratified medicine to ensure each participant receives the best possible care. This understanding, backed by scientific research, should be used to guide the design of clinical trials for these agents. The mechanism of action of a molecularly targeted agent often suggests that a biomarker can be used as a predictor of activity of the agent on the targeted disease. A biomarker driven trial is needed to confirm that the molecularly targeted agent stratifies the participant population with disease into high and low responder groups. We assume that the biomarker of interest can be dichotomised and propose a balanced parallel two-stage single-arm phase II trial that builds on existing two-stage single-arm designs. A single-arm trial cannot distinguish between a marker being predictive in the population as a whole and the agent causing an increased response in the marker positive group, but it is a first step. We compare this approach to the existing single-arm approaches, sequential enrichment, tandem two-stage, and parallel two-stage designs, and discuss the advantages and disadvantages of each design. We show that our design compares favourably to existing designs in the Bayesian framework, making a more efficient use of collected data. We recommend using the parallel two-stage balanced or sequential enrichment designs when randomisation is not practical in a phase II trial.
Insights
This study introduces a new biomarker-driven clinical trial design for molecularly targeted cancer agents. The proposed balanced parallel two-stage single-arm phase II trial efficiently stratifies patients into high and low responder groups.
Area of Science:
- Oncology
- Clinical Trial Design
- Biostatistics
Background:
- Advancements in understanding cancer mechanisms and targeted therapies necessitate stratified medicine.
- Biomarkers are crucial for predicting patient response to molecularly targeted agents.
- Current clinical trial designs require refinement for biomarker-driven studies.
Purpose of the Study:
- To propose a novel, balanced parallel two-stage single-arm phase II trial design for biomarker-driven studies.
- To evaluate the efficiency and performance of the proposed design against existing single-arm trial methodologies.
- To provide recommendations for phase II trial designs when randomization is not feasible.
Main Methods:
- Development of a balanced parallel two-stage single-arm phase II trial design.
- Comparison of the proposed design with sequential enrichment, tandem two-stage, and parallel two-stage designs.
- Utilizing a Bayesian framework to assess the efficiency of data utilization.
Main Results:
- The proposed balanced parallel two-stage single-arm design demonstrates favorable comparison to existing methods.
- The new design offers a more efficient use of collected data within the Bayesian framework.
- The study highlights the limitations of single-arm trials in distinguishing population-level marker prediction from group-specific effects.
Conclusions:
- The proposed balanced parallel two-stage single-arm phase II trial is an efficient approach for biomarker-driven studies.
- Biomarker-driven trials are essential for confirming the stratification capabilities of molecularly targeted agents.
- Sequential enrichment and balanced parallel two-stage designs are recommended for phase II trials lacking randomization.
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