Molly Billstein Leber, PharmD, BCPS, FASHP: I think this is an interesting question, because I think as a pharmacist, we probably didn’t ever think about that until biosimilars came on the market. I thought of, when darbepoetin changed their formulation and no longer made it with albumin, that didn’t require FDA approval. And I don’t think that myself or many of my colleagues necessarily questioned whether or not that should have occurred.
I think that now that biosimilars are on the market and we’re starting to recognize how many different changes in manufacturing processes that the reference product took, that I think that’s shown that we didn’t have concern then, and that we shouldn’t have concern now, and that it’s something that we need to make sure that we are very vigilant on monitoring and reporting any adverse reactions moving forward.
When you look at the analytic data and the FDA approval process, most of the work has been done up front, and the drug is highly similar to the originator product. So as long as we know the originator product works, then we should feel safe that the biosimilar product does work. And we have seen, with some of the biosimilars that are out on the market, filgrastim, for example, a biosimilar, we’ve been able to track the increase in white cell blood cell count. So, we should feel that it’s safe and effective to use outside of the FDA approved list or clinical trials for the originator product.
I think what’s going to be very difficult going forward is we are now moving from the supportive care (so the filgrastim, the pegfilgrastim, and the epoetin that are currently available) into a more curative space. And we’ve seen that kind of with infliximab, where there’s no markers to measure. And, so, I think that we are starting to see a lot of the prescriber concerns on whether or not this drug truly works. And I think as we move into more oncologic indications, I think that concern is also going to be there. We don’t have anything that proves that the biosimilar is as efficacious as the originator product, which I think people are struggling with right now.
I think that oncology is going to be very difficult. I think that with the first ones out, like rituximab, I think it’s going to be a struggle or a hard sell to get providers on that comfort level to use them. I think what we’ve seen with infliximab, at least what I’ve seen is sometimes providers forget that it’s the biologics or that they’re chronic diseases and the originator product doesn’t work 100% of the time. And they tend, if the patient was on the originator product and switches to the biosimilar, sometimes they blame the biosimilar and not the disease progression. I think we’re going to have to remind providers, again, that [not] 100% of their patients that were receiving the originator product [responded and some] had disease progression, and it’s not the drug or the biosimilar that’s causing failure, it’s actually disease progression; that’s no longer the appropriate agent to be treating that patient’s disease state. We need to look and see whether we either need to add on or switch to a different class of drugs to treat the patient.
You have an increased risk of immunogenicity every time you change cell lines or manufacturing processes, so you look at some of these drugs that have been manufactured since the late 1980s. We know that the manufacturing process has changed. We know that the cell lines have changed. We’ve changed manufacturing processes to make them more efficient and to meet the FDA requirements for the plants, so that they’re in good manufacturing. So, I think that we just need to make sure that we’re constantly monitoring and being very vigilant in reporting any immunogenicity concerns for both the originator product and the biosimilar. And the biosimilars will be made in newer facilities, so they are going to be made differently. That could be a pro or a con compared to the originator product.