A study that tests the safety, side effects, and best dose of a new treatment. Phase I/II clinical trials also test how well a certain type of disease responds to a new treatment. In the phase II part of the clinical trial, patients usually receive the highest dose of treatment that did not cause harmful side effects in the phase I part of the clinical trial. Combining phases I and II may allow research questions to be answered more quickly or with fewer patients.
Source: NCI
