The compound is not yet approved but is under active investigation — it has been tested in humans in clinical trials.IND (Investigational New Drug) status means a sponsor has provided sufficient preclinical data to justify human trials. Being in clinical trials means the FDA has permitted human research, not that the compound is safe or effective. Most compounds that enter Phase I trials never reach approval. Category 2 is meaningfully different from Category 3 (no human trials) but equally meaningfully different from Category 1 (approved).