Final answer:
An IND clinical trial may begin if the FDA has not contacted the physician within 30 days after IND submission and there is no clinical hold. The FDA can halt a therapy's development at any point, including during the IND phase, throughout clinical trials, or after marketing if problems arise.
Step-by-step explanation:
When a physician submits an Investigational New Drug (IND) application to the FDA's Center for Drug Evaluation and Research (CDER), there is a mandatory 30-day waiting period for FDA review. Assuming the FDA does not find any problems with the application, the clinical trial may commence if the FDA has not contacted the physician within this time frame. If the FDA identifies any issues, either prior to or during the clinical trial, they may issue a “clinical hold” until such problems are satisfactorily addressed. The clinical trial is a critical phase during which researchers collect and analyze data pertaining to a therapy's effectiveness and safety, leading up to the submission of a New Drug Application (NDA). The FDA can put a halt to the development or use of a therapy at any point, including upon IND submission, during clinical trials, or after manufacturing and marketing of the approved therapy.