title: A phase I/II seamless dose escalation/expansion with adaptive randomization scheme (SEARS).
abstract: BACKGROUND
  Standard drug development conducts phase I dose finding and phase II dose expansion sequentially and separately. Information between the two phases is rarely shared. Administratively, such a sequential process is time-consuming and burdensome.
  
  
  OBJECTIVE
  We propose seamless dose escalation/expansion with adaptive randomization scheme (SEARS), a seamless design that combines phase I dose escalation based on toxicity with phase II dose expansion and dose comparison based on efficacy. SEARS allows extension from phase I to phase II under one design with no gap in between and employs a dynamic and parallel procedure involving simultaneous dose escalation, dose graduation, and adaptive randomization.
  
  
  METHODS
  SEARS integrates three components into a seamless scheme. Specifically, in phase I, SEARS applies the modified toxicity probability interval (mTPI) method to monitor dose escalation based on toxicity outcome. Doses that show promising efficacy and safety are immediately graduated from phase I and placed to a phase II stage in which patients are adaptively randomized based on efficacy outcome. Phase I dose escalation, dose graduation, and phase II adaptive randomization proceed simultaneously throughout the entire trial.
  
  
  RESULTS
  Examples are given comparing SEARS with two other designs, in which superior performance of SEARS is demonstrated. An important and promising finding is that SEARS reduces sample sizes without losing power. R program and demo slides of SEARS can be obtained at http://health.bsd.uchicago.edu/yji/soft.html
  
  
  CONCLUSIONS
  We assume that the binary efficacy and toxicity response can be measured in the same time frame. This is often achievable with surrogate efficacy markers in practice.
authors.affiliation: aDepartment of Health Statistics, Fourth Military Medical University, Xi'an, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Pan
authors.forename: Fang
authors.initials: F
authors.lastname: Xie
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Jielai
authors.initials: J
authors.lastname: Xia
authors.forename: Yuan
authors.initials: Y
authors.lastname: Ji
mesh_terms: D001499:Bayes Theorem; D017321:Clinical Trials, Phase I as Topic / Q000379:methods*; D017322:Clinical Trials, Phase II as Topic / Q000379:methods*; D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020714:Maximum Tolerated Dose; D015233:Models, Statistical; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012107:Research Design; D018401:Sample Size