  Nowadays, more and more clinical trials choose combinational agents as the
intervention to achieve better therapeutic responses. However, dose-finding for
combinational agents is much more complicated than single agent as the full
order of combination dose toxicity is unknown. Therefore, regular phase I
designs are not able to identify the maximum tolerated dose (MTD) of
combinational agents. Motivated by such needs, plenty of novel phase I clinical
trial designs for combinational agents were proposed. With so many available
designs, research that compare their performances, explore parameters' impacts,
and provide recommendations is very limited. Therefore, we conducted a
simulation study to evaluate multiple phase I designs that proposed to identify
single MTD for combinational agents under various scenarios. We also explored
influences of different design parameters. In the end, we summarized the pros
and cons of each design, and provided a general guideline in design selection.
