An earlier version of this story incorrectly said that Neupogen (filgrastim) and Neulasta (pegfilgrastim) are Pfizer Inc. treatments. They are Amgen Inc. products. This version has been corrected.
So far, biosimilar uptake has been relatively slow in the U.S. since the 2015 launch of Sandoz Inc.’s Zarxio (filgrastim-sndz), the first product to use the 351(k) approval pathway. But recent and pending launches have resulted in therapeutic classes with more than one biosimilar, which may be the push that payers need to begin preferring them over their reference products, according to Zitter Insights data and, in turn, realizing savings in some costly therapeutic classes.