definiens: means a clinical study of a drug candidate in patients with the primary objective of characterizing its activity in a specific disease state as well as generating more detailed safety, tolerability, and pharmacokinetics information as described in 21 C.F.R. 312.21(b ), or a comparable clinical study prescribed by the relevant regulatory authority in a country other than the United States including a human clinical trial that is also designed to satisfy the requirements of 21 C.F.R. 312.21(a ) or corresponding foreign regulations and is subsequently optimized or expanded to satisfy the requirements of 21 C.F.R. 312.21(b ) ( or corresponding foreign regu lations ) or otherwise to enable a Phase 3 Clinical Trial ( e.g., a phase 1/2 trial ) . The relevant drug candidate may be administered to patients as a single agent or in combination with other investigational or marketed agents