Regional consistency and sample size considerations in a multiregional equivalence trial.

The main objective of a confirmatory multiregional clinical trial (MRCT) is to demonstrate the overall efficacy of test drugs in all participating regions as well as to evaluate the possibility of extrapolating the overall results to each region. With the emergence of the demands of biosimilar drugs development, some guidelines recommended using equivalence design to demonstrate the comparability of efficacy between biosimilar and reference drugs. Previous discussions about assessing regional consistency in MRCT are mainly focused on superiority or non-inferiority designs, while the extensions to equivalence designs were limited. In this work, we proposed a flexible regional consistency criterion for the MRCT with equivalence design. Based on this criterion, sample size determination and sample allocation were also discussed.