which efficacy population you are using for onc phase1/2a

For an oncology phase 1/2a study, including dose escalation and expansion periods, though efficacy is not the major objective, but still important. Using different efficacy population, actually will give different results for ORR, DCR, etc. I saw different cases, for instance: ITT(or mITT: all dosed pts having baseline measurement), OR adding other conditions on mITT, like also require: at least 1 post baseline efficacy measurement? I wonder which one should normally be used.
ITT/mITT is often used for randomized trials. For early oncology studies, the population for efficacy analysis in your question is FAS full analysis set including all subjects who took study drug and had at least one post-baseline efficacy assessment. If tumor response needs confirmed, two post-baseline assessments may be needed.