What is difference between 351(a) vs. 351(k) pathway?

the terms 351(a) pathway and 351(k) pathway are typically associated with the approval of biological products, particularly in the context of the United States Food and Drug Administration (FDA).

351(a) is the original approval pathway for innovator biologics.  351(k) biologics license application is the biosimilar application process.

351(a) pathway

• 351(a) is the original approval pathway for biologics. It is the pathway for approval of innovator biologics. It is also known as the traditional pathway for approval of innovator biopharmaceuticals.
• The 351(a) pathway refers to the approval process for the original, innovator biological products, often known as “reference” or “originator” products.
• Under this pathway, an original manufacturer or sponsor must submit a Biologics License Application (BLA) to the FDA to demonstrate the safety and efficacy of the biological product.
• The FDA evaluates the clinical data and scientific information provided in the BLA to determine whether the product should be approved for use in patients.

351(k) pathway

• The 351(k) pathway is related to biosimilar products. Biosimilars are biological products that are highly similar to, but not identical to, an already approved reference biological product.
• To gain approval through the 351(k) pathway, a manufacturer must submit a Biologics License Application (BLA) that demonstrates the biosimilarity of the product to the reference product.

At a Glance : 351(a) pathway Vs. 351(k) pathway

• 351(a) is the original approval pathway for innovator biologics.  It is also known as the traditional pathway for approval of innovator biopharmaceuticals.
• On the other hand, 351(k) biologics license application is the biosimilar application process in USFDA.