Chronic Therapy and Switching

Bruce A. Feinberg, DO: Marcus, one interesting area that’s likely to be much more significant in rheumatologic disease is going to be patients on chronic therapy and on an established agent that may now have a biosimilar, and let’s say there is a delta greater than 20%. So, it’s a different scenario of starting a patient on an agent of a class they haven’t had before versus actually switching that patient to a different drug manufactured by a different company. And, again, it’s a scenario of making that distinction between biosimilars and generics that are not identical molecules. They’ve gone through clinical testing, but different clinical testing because of the role of extrapolation, which we’ll get into later. So, I’m curious about the switching phenomenon. What’s coming out? Is there actually any guidance being provided, right now, from the [American College of Rheumatology, ACR] that’s going to help in maybe creating a national statement of how we are willing to proceed? Because, right now, it’s like you’re moving in the dark.

Marcus H. Snow, MD: Yes. These medications potentially can be lifelong, and so you start out on a biologic medication—infliximab, for example. You start out on infliximab and you’re on infliximab for 10, 12 years. And then, your carrier decides, “Now I’m going to switch you to the biosimilar, infliximab.” It’s a different molecule, as you mentioned. And for your immune system, it has been proven to be efficacious. It’s been proven to have similar effects. It was proven to be near identical, but it’s not identical. Does your body react to that long term? Do you lose efficacy? Does it increase your immunogenicity, which basically means that you have more drug-to-drug antibodies because you switched from product A to product B and maybe then to product C then back to product B, depending on how the winds blow with the formulary? That’s something that, as rheumatologists, we are very concerned about. And it’s something that we are trying to help regulate with the FDA. We’re trying to work with the FDA to offer some guidance, and this is hopefully for an interchangeable medication, which not all biosimilars, at this point, have.

Bruce A. Feinberg, DO: Have any been granted interchangeability? I don’t think any have.

Marcus H. Snow, MD: I have not seen that any have been granted interchangeability.

Hope S. Rugo, MD: If somebody has been on this drug for 10 years, haven’t they already seen different formulations of the same product over time? I mean that you change where you’ve made it or where you get it from or that, in fact, you change the process. And that does occur, over time, for most of these drugs.

Marcus H. Snow, MD: Absolutely, and I think that is a great point. I don’t know how many variations of infliximab there have been, but there have been well over 20 versions of infliximabs, and they have to file with the FDA and let them know that they’re changing a process in their manufacturing.

Hope S. Rugo, MD: But, we don’t necessarily know that as prescribers.

Marcus H. Snow, MD: No, absolutely not. And so there is probably some lot-to-lot variability, and my patient has likely seen multiple versions of the originator product. The question is, ultimately, how does that happen in the long run? We think it will be okay. I think that, innately, we have no evidence that it will be a horrible thing, but I think that we have to take a lot of caution with this because we just don’t know. There are no studies with this. You’re going from products that are made in a different cell or made in a different lab, and these products are different.