What is the increase in white blood cell count after administration of Udenyca (pegfilgrastim)?

From the Guidelines

Udenyca (pegfilgrastim-cbqv) typically increases white blood cell counts significantly, with most patients experiencing a 10-fold or greater increase in neutrophil counts within 24-72 hours after administration. The peak effect usually occurs 3-5 days after injection, with absolute neutrophil counts often rising to levels between 15,000-45,000 cells/μL, though individual responses vary 1. This medication works by stimulating bone marrow to produce neutrophils, a type of white blood cell crucial for fighting infections.

Key Points

• The increase in white blood cell count is temporary and designed to prevent neutropenia (low white blood cell count) in patients undergoing chemotherapy.
• White blood cell counts generally return to baseline levels within 1-2 weeks after the last dose.
• Patients should be aware that mild bone pain is a common side effect due to increased bone marrow activity.
• Regular blood tests are typically recommended to monitor white blood cell counts during treatment with Udenyca.

Administration and Dosage

• Pegfilgrastim 6 mg should be administered once 1 to 3 days after chemotherapy if possible 1.
• The medication is not currently indicated for stem-cell mobilization, and the 6-mg formulation should not be used in infants, children, or small adolescents who weigh 45 kg 1.

Clinical Evidence

• Clinical efficacy data from trials have demonstrated that a single pegfilgrastim injection per cycle is as effective at reducing the duration of severe neutropenia as daily injections of filgrastim 1.
• The risk of febrile neutropenia (ANC 0.5 109/L with fever 38.2°C) was significantly lower in patients receiving pegfilgrastim than for those receiving filgrastim 1.

From the FDA Drug Label

5.6 Leukocytosis White blood cell (WBC) counts of 100 x 10^9/L or greater have been observed in patients receiving pegfilgrastim products. The increase in white blood cell count after administration of Udenyca (pegfilgrastim) can be 100 x 10^9/L or greater 2.

From the Research

Increase in White Blood Cell Count after Udenyca (Pegfilgrastim) Administration

• The administration of pegfilgrastim has been shown to increase white blood cell count in patients, with varying degrees of response observed in different studies 3, 4, 5, 6.
• A study published in 2005 found that white blood cell recovery was observed within 1-3 days in 75% of patients treated with pegfilgrastim, and within 5 days in the remaining 25% 3.
• Another study published in 2019 found that leukocyte overshoot, defined as a white blood cell count ≥10,000/mm3 exceeding the reference value, was observed in 71.2% of occasions and 76.4% of patients treated with pegfilgrastim 4.
• The maximum white blood cell count ≥30,000/mm3 was observed in 30.5% of occasions and 45.5% of patients, with the highest frequency of occurrence on day 1 after pegfilgrastim administration 4.
• A study published in 2007 reported a case of pegfilgrastim-induced hyperleukocytosis in a pediatric patient, with a white blood cell count of 149 x 10(3)/microL and absolute neutrophil count of 110 x 10(3)/microL observed 6 days after administration of pegfilgrastim 6.
• The increase in white blood cell count after pegfilgrastim administration can be significant, with median white blood cell counts ranging from 7,200 to 35,000/uL observed in one study 5.

Timing of White Blood Cell Count Increase

• The increase in white blood cell count after pegfilgrastim administration can occur within 1-3 days, with the highest frequency of occurrence on day 1 after administration 3, 4.
• Leukocyte overshoot has been observed to occur most frequently on day 1 after pegfilgrastim administration, with 39.3% of occasions observed on this day 4.
• The white blood cell count can remain elevated for several days after pegfilgrastim administration, with median white blood cell counts ranging from 1,100 to 17,400/uL observed on day 14 after administration 5.