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Interchangeability and Rheumatology Prescribing Practices


Amanda Forys, MSPH: Dr. Worthing, we don’t have an interchangeable biosimilar on the market yet, but how would the designation of interchangeability affect you as a provider in your clinical prescribing practices?

Angus Worthing, MD, FACR, FACP: Great question. Molly is right—doctors and patients have been waiting, I think, for the interchangeability guidance. I think it would help build confidence. As a rheumatologist and somebody who writes prescriptions for biologics, there’s 2 general situations in which a doctor might write a prescription for a biologic. One instance is for a patient whom hasn’t taken the drug yet, and they’re new to the drug. And then, there’s the situation where we’re writing a prescription for somebody who’s already been on the reference product for some time, might have been doing well, and we’re writing a prescription for them (for the biosimilar) to change over and move. I think in the first instance, we’re getting a really good amount of confidence in the FDA pathway, which shows that the structure, and function, and anticipated usefulness, safety, and efficacy of biosimilars are biosimilar to their reference products. And to me, that kind of matches up with the first clinical situation—where I’m prescribing a biosimilar to a patient who’s not yet taking a drug.

Where the interchangeability pathway comes in boosting confidence is in that second situation—where a patient might be doing well on a drug and both the doctor and the patient are interested in knowing if a biosimilar (which might be cheaper or they might have easier access to it), is going to work the same way, not cause any more side effects, and still keep their disease under control. And that’s where I think the pathway that the FDA has drafted, which we saw this winter, really helps boost confidence. The pathway suggests a clinical trial design where manufacturers start patients on the biologic reference product and then switch 3 times (to the biosimilar, back to the reference product, and then back to the biosimilar), and confirm that they’re just as safe and effective. I think that will help (in that situation). We can be confident in telling a patient, “This drug might seem new to you, but it’s going to work just as well as the drug you’ve been taking.”

Amanda Forys, MSPH: That actually ties a little bit into a follow up question I was thinking of. You’re currently comfortable with the pathway. You’re currently comfortable with a patient (as you’re saying, kind of a new patient) and a new start with the FDA guidance. This is really about that switch patient (your continuing patient), and thinking about switching therapy. What evidence are you currently relying on (looking at products that have been approved) to make sure that you’re comfortable prescribing them?

Angus Worthing, MD, FACR, FACP: Right now, we’re looking at 2 different kinds of evidence, mainly. One is looking at analytical data. That’s data in the test tube, and data about the molecule and how it works, and looking at the mechanism of action to make sure it works the same way as the reference product. And then, the second kind of data is clinical trial data. Clinical trial data includes putting the drug into people who have the disease (where the drug is applying for indication) and making sure that it works just as well and has as few safety signals compared to the reference product. So, right now, we’re looking at those 2 kinds of data and judging that these biosimilars work just as well as their reference products.

Ha Kung Wong, JD: Can I ask a question, Angus? I’m kind of curious about this. As a first-designated interchangeable gets approved into the market, do you think this is going to be a tipping point, where because biosimilar uptake has been a little bit slower than anticipated, more physicians will be more likely to prescribe biosimilars? Or, do you think that they’re going to start saying, “Well, biosimilars are somewhat inferior to interchangeables,” and just ignore them because they don’t have switching studies? They don’t have the presentation studies and the FDA’s blessing.

Angus Worthing, MD, FACR, FACP: Great question, Ha Kung. I think that depends on a lot of variables. One is looking at how good the data is for that interchangeable. We want to see the data from clinical trials right in the FDA package insert. We want to know about them. All doctors, when they’re talking to their patients, should learn about the drug and how well it works. I think if that happens, and then on the payer side, people who are paying for the drugs (insurance companies, pharmacy benefits managers, the government), if they also see the value of the interchangeable drug, I think that we’ll get good market uptake. You were referencing how the biosimilars market hasn’t taken on as quickly as hoped. I think we’re all interested (from a provider’s and patient’s perspective), in getting the prices down. That’s all we’re talking about today with biosimilars—trying to reduce the prices. And really, that’s probably going to hinge on market uptake and getting more biosimilars into the market.

Molly Burich, MS: Yes, and I would totally agree, Dr. Worthing. Coming from a manufacturer’s perspective, I think it’s very important that all stakeholders understand that a biosimilar that’s “just a biosimilar” is not less safe or less quality. It’s quite the opposite, actually. I think the bar for biosimilarity is high, to Dr. Worthing’s point around analytics, in particular. But, I think it’s going to be beholden for all stakeholders to understand that, in fact, a product with just a biosimilarity designation isn’t less anything. It’s different. If you pursue interchangeability, the purpose of that is different. Therefore, I think to Dr. Worthing’s point, manufacturers will look at things, product by product, and make that decision, which is a very significant investment. As Dr. Worthing mentioned, it’s a large-scale clinical trial. Because of the number of switches, it requires a lot of time. Therefore, it’s not an overnight proposition.

I think we’ll see some molecules in some markets where interchangeability is very important, and I think we’ll see other areas where it’s less important (because of how the product is given to the patient or in the disease area). If it’s for an acute use in oncology, I think you’ll see that things will look very different (from an interchangeability standpoint) versus in a chronic use, where a patient might be on it for years or decades.

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