Context: Recently an Indian pharma company has been granted a USFDA approval for Insulin Glargine, a biosimilar. 
About Biosimilar

• It is a biological product that is developed to be similar to an already FDA-approved biologic, known as the reference product. It can be tempting to think of a biosimilar as a “generic” version of the reference product.
• Biosimilars may have minor differences in clinically inactive components. However, a biosimilar is not considered a “generic” in the same way that a traditional drug is determined to be a generic.
• But biosimilar is not an exact duplicate of another biologic. There is a degree of natural variability in all biological products; it is not possible to generate a precise copy of a product that comes from living cells. All biologics—including reference products—show some batch-to-batch variation.

Biosimilars vs. Generics

• Generic medicines are chemically synthesized while biosimilars are grown in complex living systems.
• Biologic medicines are large, complex molecules or mixtures of molecules that may be composed of living material — as such, biosimilars are unlikely to be exact copies of their reference products.
• Unlike generic medicines, the FDA requires a biosimilar to be highly similar, but not identical to the existing biologic medicine, or “reference product”
• A biosimilar also must demonstrate no clinically meaningful differences in efficacy, safety, and potency with its reference product.
• Biosimilars are reviewed and approved under the abbreviated FDA review process known as the 351(k) pathway.
• Per FDA guidance, the Agency reviews the totality of evidence and does not necessarily focus on one type of study to evaluate a manufacturer's application for demonstration of biosimilarity.
• Most evidence submitted for FDA review of a reference product is derived from the clinical studies to establish the products efficacy and safety profiles
• The manufacturer of a biosimilar demonstrates biosimilarity primarily from nonclinical analyses in a stepwise approach that includes examining the structure and functional nature of the biosimilar molecule. 
• Non-clinical and clinical studies are both designed to resolve any uncertainty that the biosimilar is highly similar to the reference product.