Pegfilgrastim-induced leukocytosis and hyperleukocytosis

Objective: To report a case of leukocytosis (LCT) and hyperleukocytosis (HLCT) episodes post Pegfilgrastim (Neulasta) administration. Case Summary: A 74-year-old female presented with several episodes of LCT and HLCT following administration of Pegfilgrastim while undergoing adjunct dose dependent chemotherapy for adenocarcinoma of the gallbladder. The patient had completed cycle 6, day 8 of chemotherapy and subsequently received Neulasta 48 hours later. Two days later, she presented to the ER with white blood cell (WBC) count of 110K. Prior to Neulasta administration, her WBC counts were within normal range and after each episode of leukocytosis, the patient’s WBC count trended downward. Upon consultation, hematology considered Pegfilgrastim as a likely cause for this patient’s WBC cycling and HLCT. Discussion: Pegfilgrastim-induced HLCT occurs in less than 1% of patient cases. Dose-dependent chemotherapy combined with Pegfilgrastim treatment is an optimal treatment option to reduce the length of chemotherapy schedules and risk of febrile neutropenia. Following the dosing of Pegfilgrastim, the drug clearance is mediated by neutrophil receptors which results in a reduction of ANC values. Conclusions: Further studies are needed to determine the optimum timing and dosage of Pegfilgrastim to offer maximum myeloprotective benefit while also minimizing the risks of adverse events such as leukocytosis and hyperleukocytosis experienced by our patient.