To what degree are doctors using filgrastim-sndz (Zarzio) instead of filgrastim (Neupogen) in the US? I suspect many doctors and patients would be reluctant to switch to a non-interchangeable biosimilar, but haven't found any papers studying it's usage here after it's approval last year.
Filgrastim-SNDZ (Biosimilar Neupogen) Useage?
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I sit on my hospital's Oncology P&T committee and we just approved (over my objection) the use of one of the biosimilars (I don't remember which one) in place of Neupogen. I use Neupogen about 6 times a year so it won't affect me that much (and I suspect Amgen will do a deal to drop the price anyway).
The reason you haven't seen any studies is that the FDA doesn't really require it. No head-to-head comparison is necessary. They just have to prove that it keeps the WBC up and prevents infections.
The reason you haven't seen any studies is that the FDA doesn't really require it. No head-to-head comparison is necessary. They just have to prove that it keeps the WBC up and prevents infections.
Thanks! Can you elaborate on why you objected?
I think you're being imprecise here, because there is a practice/common definition of "biosimilar" and a legal one. The former is a biologic that is highly similar to another product. Legally, biosimilars are highly similar products approved through the 351(k) pathway, and they need to show "no clinically meaningful difference" so there has to be a head-to-head comparison.
From what I can see in CDER, there are three FDA approved "biosimilars." The only one that fits the legal definition is Zarxio (filgrastim-sndz), for which there was a head-to-head study which basically showed it was identical except for slightly lower exposure for filgrastim-sndz since it used a different buffer (I suspect it would be "interchangeable" if the FDA had sorted out what the term meant). The other filgrastim biosimilar made by Teva, Granix (tbo-filgrastim), went through a BLA and is legally a different drug than Neupogen even though biochemically it's basically the same thing. I don't believe it nor the other BLA-pathway biosimilar (Zaltrap/ziv-aflibercept) had to show head-to-head for approval.
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Because I think the FDA pathway is bulls*** frankly. I'm all for "generics" but if you don't have to prove efficacy to the SOC medication to get approval then I don't believe it.
Otherwise po-tay-toh, po-tah-toh.