Eflapegrastim

Febrile neutropenia (FN), defined as the co-occurrence of fever (temperature > 38 ◦C) and severe neutropenia (ANC < 500 cells/mm), is a potential side effect of myelosuppressive chemotherapy in which the patient develops an infection during a period of significant neutropenia. It typically develops during the first cycle of chemotherapy and is associated with an increased risk of morbidity and mortality. The primary factor associated with FN risk is the chemotherapy regimen being administered - regimens are classified as either high-, intermediate-, or low-risk for FN, and relevant guidelines recommend the use of pharmacologic prophylaxis against FN in patients receiving high-risk regimens and those receiving intermediate-risk regimens who have ≥1 additional risk factor.

Granulocyte-colony stimulating factors (G-CSFs) - which include filgrastim and pegfilgrastim - were first used clinically in the 1990s and are the primary means of prophylaxis against chemotherapy-induced neutropenia, including FN. They trigger signaling pathways that control the differentiation, proliferation, migration, and survival of neutrophils, thereby helping to restore depressed neutrophil counts.

Eflapegrastim is a form of recombinant human G-CSF comprising a human G-CSF analog coupled to the Fc fragment of human IgG4 via a polyethylene glycol linker. In September 2022, eflapegrastim was approved by the US FDA as a prophylactic against infection, as manifested by febrile neutropenia, in patients receiving certain myelosuppressive anti-cancer drugs.