The phase II/III transition. Toward the proof of efficacy in cancer clinical trials

Control Clin Trials. 2000 Aug;21(4):360-8. doi: 10.1016/s0197-2456(00)00056-8.


Few phase III investigations show a benefit for an experimental treatment when compared to a standard therapy or placebo. This illustrates the need for more reliable estimates of treatment effects from the phase II investigations used to design the more definitive phase III trials. In this manuscript, we examine four aspects of phase II clinical trial designs: (1) selecting endpoints; (2) defining the patient population for evaluation; (3) determining a level of activity that would justify a phase III trial; and (4) estimating sample sizes. In each area, problems with the conventional approaches are discussed and alternatives for the successful transition of phase II results to a phase III setting are suggested. An application of the design for patients with androgen-independent prostate cancer is illustrated.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use*
  • Clinical Trials, Phase II as Topic / methods*
  • Clinical Trials, Phase II as Topic / statistics & numerical data
  • Clinical Trials, Phase III as Topic / methods*
  • Clinical Trials, Phase III as Topic / statistics & numerical data
  • Data Interpretation, Statistical
  • Humans
  • Male
  • Patient Selection
  • Prostatic Neoplasms / drug therapy
  • Prostatic Neoplasms / mortality
  • Research Design*
  • Sample Size
  • Survival Analysis


  • Antineoplastic Agents