In what scenario would a firm not need to submit a new NDA?

When considering the need for a new New Drug Application (NDA), it is essential to recognize the specific scenarios outlined by regulatory agencies. Modifying an approved drug's labeling does not require a new NDA because labeling changes are typically managed through a supplemental NDA or a labeling submission under an existing NDA. This allows for flexibility in updating information related to the drug, such as safety warnings, administration instructions, or indication descriptions, without the need for a complete re-evaluation or new application process.

In contrast, changes such as altering the product name or seeking approval for a new indication are more significant and may lead to a new NDA submission due to the potential impacts on the drug's safety, efficacy, and market identity. Extending patent protection, while important, also does not require an NDA, as it is typically handled through legal pathways unrelated to the regulatory approval of the drug itself. Therefore, the modification of an approved drug’s labeling is correctly noted as a scenario where a new NDA is not necessary.