What is pegfilgrastim approved for?

It is FDA-approved to decrease infection (febrile neutropenia) in patients on myelosuppressive chemotherapy, and separately to increase survival after acute radiation exposure; it is not approved for stem-cell mobilization.

When is it given relative to chemotherapy?

It is typically given about a day after chemotherapy and is not administered in the period shortly before or immediately after cytotoxic drugs.

Does pegfilgrastim cause more bone pain than filgrastim?

Comparative trial data found bone-pain frequency and severity similar between the two products.

What serious risks are on the label?

Rare but serious risks include splenic rupture, acute respiratory distress syndrome, capillary-leak syndrome, serious allergic reactions, sickle-cell crises, glomerulonephritis, and aortitis.

EMA-approvedaka Neulasta

Pegfilgrastim — Complete Research Guide (2026)

Last updated 2026-06-30

TL;DR

Pegfilgrastim (also known as Neulasta) is a peptide catalogued under Immune (PEG-G-CSF). Neutral reference entry; EU status: EU-approved prescription medicine.

What is Pegfilgrastim?

Pegfilgrastim is filgrastim (recombinant human G-CSF) covalently bound to a polyethylene-glycol moiety, marketed as Neulasta, which slows renal clearance and gives it a long duration of action.

It is an FDA-approved prescription biologic (first approved 2002) to decrease the incidence of infection, as manifested by febrile neutropenia, in patients receiving myelosuppressive anticancer chemotherapy, and is additionally approved to increase survival in acute radiation syndrome; it is given once per chemotherapy cycle and is not indicated for stem-cell mobilization.

Evidence is human and strong, based on randomized phase III trials against daily filgrastim and placebo.

How does Pegfilgrastim work?

Like filgrastim, pegfilgrastim binds the G-CSF receptor to stimulate neutrophil proliferation, differentiation, and release from the marrow.

Pegylation confers self-regulating, neutrophil-mediated clearance, so a single dose sustains G-CSF activity across the neutrophil nadir of a chemotherapy cycle.

What does the research say about Pegfilgrastim?

A single once-per-cycle pegfilgrastim dose matched daily filgrastim for duration of severe neutropenia in breast-cancer chemotherapy. ^[1]
First- and subsequent-cycle pegfilgrastim significantly reduced febrile neutropenia incidence versus placebo in breast-cancer chemotherapy. ^[3]
Fixed-dose single-administration pegfilgrastim was non-inferior to daily filgrastim for neutropenia outcomes across myelosuppressive chemotherapy. ^[2]

Clinical research & studies

The references below are the primary sources cited throughout this guide. Each links directly to PubMed or the regulator. Where evidence is preclinical (animal or in-vitro), that is stated rather than implied.

[1] Blinded, randomized, multicenter study to evaluate single administration pegfilgrastim once per cycle versus daily filgrastim as an adjunct to chemotherapy in patients with high-risk stage II or stage III/IV breast cancer — Holmes FA et al., Journal of Clinical Oncology 2002. (Randomized controlled trial)
[2] A randomized double-blind multicenter phase III study of fixed-dose single-administration pegfilgrastim versus daily filgrastim in patients receiving myelosuppressive chemotherapy — Green MD et al., Annals of Oncology 2003. (Randomized controlled trial)
[3] First and subsequent cycle use of pegfilgrastim prevents febrile neutropenia in patients with breast cancer: a multicenter, double-blind, placebo-controlled phase III study — Vogel CL et al., Journal of Clinical Oncology 2005. (Randomized controlled trial)
[4] Comparable efficacy and safety profiles of once-per-cycle pegfilgrastim and daily injection filgrastim in chemotherapy-induced neutropenia: a multicenter dose-finding study in women with breast cancer — Holmes FA et al., Annals of Oncology 2002. (Randomized dose-finding trial)
[5] Bone pain associated with once-per-cycle pegfilgrastim is similar to daily filgrastim in patients with breast cancer — Kubista E et al., Clinical Breast Cancer 2003. (Analysis of randomized trial data)
[6] Pegfilgrastim: using pegylation technology to improve neutropenia support in cancer patients — Molineux G et al., Anti-Cancer Drugs 2003. (Narrative review)

Dosing context

This is not medical advice or a usage recommendation. Dosing figures are reported research context only, cited from the published literature.

Pegfilgrastim is a clinician-prescribed single fixed-dose subcutaneous injection administered once per chemotherapy cycle, typically the day after chemotherapy, with an on-body injector option in some settings.

This is context only and not a dosing recommendation; use, timing, and monitoring are directed by the treating oncology team.

Side effects & safety profile

Bone and musculoskeletal pain is the most common adverse effect, comparable in frequency to daily filgrastim. As with all G-CSF products, splenic enlargement occurs and splenic rupture - though rare - has been reported and can be fatal.

Labeling warns of acute respiratory distress syndrome, serious allergic reactions, capillary-leak syndrome, sickle-cell crises, glomerulonephritis, and aortitis.

Because it is long-acting, it is generally not given between about 14 days before and 24 hours after cytotoxic chemotherapy.

Stacking & combinations

It is used as supportive care within a chemotherapy regimen rather than combined with other growth factors, and stacking multiple CSF products is not standard practice.

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Frequently asked questions

Pegfilgrastim is filgrastim with an attached PEG chain that makes it long-acting, so one dose per chemotherapy cycle replaces the several daily filgrastim injections.

References

[1] Blinded, randomized, multicenter study to evaluate single administration pegfilgrastim once per cycle versus daily filgrastim as an adjunct to chemotherapy in patients with high-risk stage II or stage III/IV breast cancer — Holmes FA et al., Journal of Clinical Oncology 2002. PMID: 11821454. View sourceStudy: Randomized controlled trialOnce-per-cycle pegfilgrastim was comparable to daily filgrastim for neutropenia control.
[2] A randomized double-blind multicenter phase III study of fixed-dose single-administration pegfilgrastim versus daily filgrastim in patients receiving myelosuppressive chemotherapy — Green MD et al., Annals of Oncology 2003. PMID: 12488289. View sourceStudy: Randomized controlled trialFixed-dose pegfilgrastim was non-inferior to daily filgrastim for duration of severe neutropenia.
[3] First and subsequent cycle use of pegfilgrastim prevents febrile neutropenia in patients with breast cancer: a multicenter, double-blind, placebo-controlled phase III study — Vogel CL et al., Journal of Clinical Oncology 2005. PMID: 15718314. View sourceStudy: Randomized controlled trialPegfilgrastim reduced febrile neutropenia incidence versus placebo from the first cycle onward.
[4] Comparable efficacy and safety profiles of once-per-cycle pegfilgrastim and daily injection filgrastim in chemotherapy-induced neutropenia: a multicenter dose-finding study in women with breast cancer — Holmes FA et al., Annals of Oncology 2002. PMID: 12123336. View sourceStudy: Randomized dose-finding trialPegfilgrastim showed comparable efficacy and safety to daily filgrastim across doses.
[5] Bone pain associated with once-per-cycle pegfilgrastim is similar to daily filgrastim in patients with breast cancer — Kubista E et al., Clinical Breast Cancer 2003. PMID: 12636878. View sourceStudy: Analysis of randomized trial dataBone-pain frequency and severity were similar between pegfilgrastim and daily filgrastim.
[6] Pegfilgrastim: using pegylation technology to improve neutropenia support in cancer patients — Molineux G et al., Anti-Cancer Drugs 2003. PMID: 12679729. View sourceStudy: Narrative reviewReviews how pegylation yields self-regulating clearance enabling once-per-cycle dosing.

This article is for educational and research purposes only. Peptides discussed here are not approved for human consumption by the FDA, EMA, or equivalent regulators outside of specific clinical contexts. Always consult a licensed medical professional before any therapeutic use.