clinical trial phase clinical trial early phase 1 Pre-Clinical Phase Leon Li, Asiyah Lin, Oliver He clinical trial phase 0 https://en.wikipedia.org/wiki/Clinical_trial Early Phase 1 http://purl.obolibrary.org/obo/NCIT_C54721 C1882358 C54721 A clinical trial phase that is designed to use an investigational agent that is available only in very limited quantities and which has never previously given to humans or for which there is extremely limited human experience. Phase 0 clinical trials are intended to enable researchers to understand the path of the drug in the body and its efficacy. Adverse event reporting in Phase 0 trials is expedited. [def-source: NCI]