On January 2, 2020, Spectrum Pharmaceuticals announced that the FDA had accepted its 351(a) application for a novel granulocyte colony-stimulating factor (G-CSF), eflapegrastim. And no, the name is not misspelled here; the name is a close cousin of pegfilgrastim.

As reported in 2018 by the Center for Biosimilars, this agent showed promise versus pegfilgrastim. As with the pegfilgrastim biosimilars, the road to approval for Spectrum has been bumpy. The manufacturer decided to withdraw its original application for approval in 2019 after FDA required more information on manufacturing of the eflapegrastim.

Not a follow-on agent or a biosimilar, eflapegrastim is intended to be introduced as a new innovative brand. As the early results hinted at somewhat greater potency than Neulasta^®, the current application cites clinical data that supports noninferiority of eflapegrastim to Neulasta in terms of preventing febrile neutropenia. The study objective was to demonstrate noninferiority, not superiority. The phase 3 RECOVER investigation also found no significant differences in terms of safety between the agents.

One might ask, what’s the point of this product if it isn’t an improvement over pegfilgrastim? Well, it may be proven to be superior in some future study (though no further comparator investigations are currently listed on ClinicalTrials.gov).

It might possibly be an example of corporate inertia. Pfizer went through with its FDA approval of Ixifi™ (infliximab) even though it knew that it would not be marketing this biosimilar in the US. When Spectrum first submitted its application in December 2018, there were already two approved pegfilgrastim biosimilars, and one, Fulphila^®, was being marketed. One wonders why Spectrum may have believed another branded G-CSF could still be an important player at that time.

Or the pharmaceutical company understood the small portion of marketshare that eflapegrastim could obtain, in the face of competition with three biosimilars and two forms of Neulasta in the long-acting G-CSF market. Even a small slice will be a difficult reach for Spectrum, especially since it will have to contend with actively lowering prices for the pegfilgrastim category.

The Food and Drug Administration set a PDUFA date of September 24, 2020 for eflapegrastim.