Dr Gary Lyman: Uptake of Filgrastim vs Pegfilgrastim Biosimilars

Gary Lyman, MD, MPH, an oncologist and hematologist, compares the uptake of filgrastim biosimlars with pegfilgrastim biosimilars.

Gary Lyman, MD, MPH, is an oncologist, hematologist, and public health researcher who has long been an advocate for biosimilars. He has also developed guidelines in support of using biosimilars in the oncology space.


We’ve seen a much higher uptake of filgrastim biosimilars compared with pegfilgrastim biosimilars. Could you briefly explain the reason for this difference and what the financial implications are?

Lyman: My personal view is that this is quite complicated and I haven't seen studies that have necessarily dived sufficiently into detail, both on the provider and payer side. But we do know that the filgrastim biosimilars were approved first. So, they've been in the marketplace the longest. In fact, the first official biosimilar was a biosimilar G-CSF [granulocyte-colony stimulating factors] for filgrastim. They've been around longer and when there was no pegfilgrastim biosimilar competition, there was a lot of gravitation over to filgrastim, even though, prior to that, pegfilgrastim, a single injection long-acting form of G-CSF, had gained a great deal of market share in the days leading up to biosimilars. Because of the cost competition when the biosimilar filgrastim was launched, it rapidly took a big part of that market share. Now, we have 4 biosimilar versions of pegfilgrastim.

I say it's complicated, because I think there's another factor here, which is when clinicians have prescribed the filgrastim biosimilar, they often use less than the FDA recommended dosing and scheduling of 7 to 10 days to allow for neutrophil recovery. They've often found that they can get by with, or at least they feel they can get by with, a shorter duration of filgrastim of 5 days or 7 days. Unfortunately, [sometimes] even less than that, which has no evidence, but nevertheless comes with a much lower cost, because you're cutting the duration of the treatment. Now that there are biosimilar pegfilgrastim, which are still fairly costly, I think clinicians, health systems, and payers have been a little reluctant to all of a sudden embrace these more costly versions of G-CSF. So, I think very few patients would not favor the single injection of pegfilgrastim.

Again, price is driving so much of this and I think as long as there's a big differential between a typical course of filgrastim treatment and a single dose of pegfilgrastim treatment, that cost is going to influence what the preferred agents and the pressures are to use filgrastim. So, again, every all else being the same left to the clinician or the patient, I think pegfilgrastim would be the favorite but when cost and reimbursement factors weigh in, we see this dynamic playing out where there's likely to be greater use of filgrastim, or at least a substantial proportion of G-CSFs will be the short-acting daily injections.