clinical trial Phase I/II Trial Phase I/II Trial PHASE I/II TRIAL Trial Phase 1/2 Trial Phase 1-2 1-2 C1519043 A trial to study the safety, dosage levels, and response to a new treatment. Trials that are a combination of phases 1 and 2. C15693 A clinical research protocol designed to study the safety, dosage levels and response to new treatment. Phase I/II trials combine a Phase I and a Phase II trial of the same treatment into a single protocol. Phase_I_II_Trial CDISC Research Activity Phase I/II trial Phase I/II Trial A class of clinical study that combines elements characteristic of traditional Phase I and Phase II trials. See also Phase I, Phase II.