What Are Biosimilars?

Kashyap Patel, MD: A biosimilar is a compound that is produced by living organisms. It bears structural analytical similarities as well as chemical compositions that are pretty identical to the parent compound. It also has the similarity in the pharmacokinetics, pharmacodynamics, and immunogenicity. Safety- and efficacy-wise, it’s pretty identical to its parent biological compound. And they are different from generics. A generic is 1 simple chemical that could be broken out into multiple small tablets. The biosimilar is actually a lot more complex and complicated to manufacture.

Biosimilars, because they are a new class of drugs, the patients and physicians are still learning to understand what it is. The traditional concept is the biosimilars are identical to generics. That’s not the case. Again, there’s a more complicated process involving manufacturing, purifying, or identifying, analyzing, and evaluating a biosimilar.

Sometimes hundreds of millions of dollars are spent for biosimilar compounds because of the complexity of the way it’s manufactured. Physicians still are learning about that as a new class. The biosimilars came to the US market in 2016, and physicians are still learning about what they are. Patients are having difficulty coming to understand that they’re not inferior; there’s some perception that biosimilars are different. In terms of its efficacy, they are not. I think the FDA has provided a very rigorous path for a biosimilar in the pathway 351(k). But look at the totality of evidence. In my opinion, biosimilars are identical to parent compounds in terms of efficacy, safety, and, immunogenicity.

It’s somewhat more complicated and confusing compared with the parent compound, and I think there are genuine reasons. For the FDA to track down anything that is a biosimilar compound, they want to make sure that postapproval process, the FDA and the regulatory agencies can track the safety and efficacy of the biosimilar. Instead of giving all biosimilars 1 single name, because the FDA expects multiple companies to come in the same biosimilar space, they give a 4-letter [suffix] for safety and efficacy, as well as any adverse events to track down the biosimilar by the last 4 letters. That could be assigned to the unique Q code, so we could track the Q code and the last 4 letters attached to each biosimilar. Anything that’s led to that specific product can be tracked.