Phase II clinical trials: issues and practices

Most of the Phase II trials are conducted for evaluating the efficacy of cancer treatment and advancing it to Phase III studies. The future progress in improving cancer therapy can be expedited by better prioritizing the options for Phase III evaluations. Phase II trials, historically, have been key in this prioritization process. Relevant trial designs that have been used include Phase II selection designs, randomized phase II designs that include a reference standard-treatment control arm, phase I/II designs, phase II/III designs. The keys issues in these study designs are: i. Selection of historical control ii. Heterogeneity iii. Adaptive signature design iv. Randomization (choice Phase II versus Phase IIb) v. Balancing randomization while maintaining the expected sample size in the phase II clinical studies