  In oncology, phase II or multiple expansion cohort trials are crucial for
clinical development plans. This is because they aid in identifying potent
agents with sufficient activity to continue development and confirm the proof
of concept. Typically, these clinical trials are single-arm trials, with the
primary endpoint being short-term treatment efficacy. Despite the development
of several well-designed methodologies, there may be a practical impediment in
that the endpoints may be observed within a sufficient time such that adaptive
go/no-go decisions can be made in a timely manner at each interim monitoring.
Specifically, Response Evaluation Criteria in Solid Tumors guideline defines a
confirmed response and necessitates it in non-randomized trials, where the
response is the primary endpoint. However, obtaining the confirmed outcome from
all participants entered at interim monitoring may be time-consuming as
non-responders should be followed up until the disease progresses. Thus, this
study proposed an approach to accelerate the decision-making process that
incorporated the outcome without confirmation by discounting its contribution
to the decision-making framework using the generalized Bayes' theorem. Further,
the behavior of the proposed approach was evaluated through a simple simulation
study. The results demonstrated that the proposed approach made appropriate
interim go/no-go decisions.
