ABSTRACT
An adaptive seamless phase-II/III design is one of the most attractive adap-
tive designs. A seamless adaptive design is a combination of traditional
phase-II and phase-III trials. In seamless design, there is usually a so-
called learning phase that serves the same purpose as a traditional phase-II
trial, followed by a confirmatory phase that serves the same objectives as a
traditional phase-III trial (Figure 15.1). Compared to traditional designs,
a seamless design can reduce sample size and time-to-market for a positive
drug candidate. The main feature of a seamless design is the drop-loser
mechanism. Sometimes it also allows for adding new treatment arms. A
seamless design usually starts with several arms or treatment groups. At the
end of the learning phase, inferior arms (losers) are identified and dropped
from the confirmatory phase.
