Pelmeg (Pegfilgrastim)
Long-acting granulocyte colony-stimulating factor (G-CSF) — PEGylated biosimilar for reducing febrile neutropenia during cytotoxic chemotherapy
Pelmeg is a European Medicines Agency (EMA) approved biosimilar of pegfilgrastim, a long-acting granulocyte colony-stimulating factor (G-CSF). It is used to reduce the duration of severe neutropenia and the incidence of febrile neutropenia in adults receiving cytotoxic chemotherapy for malignancy. Unlike daily filgrastim injections, Pelmeg is given as a single 6 mg subcutaneous injection once per chemotherapy cycle, approximately 24 hours after the completion of each cycle. The PEGylation of the filgrastim molecule reduces renal clearance and extends the serum half-life, providing prolonged neutrophil support across the chemotherapy cycle.
Quick Facts
Key Takeaways
- Pelmeg is a long-acting PEGylated G-CSF biosimilar that stimulates neutrophil production in the bone marrow, reducing the risk of infection during chemotherapy
- A single 6 mg subcutaneous injection per chemotherapy cycle replaces 10–14 daily injections of conventional filgrastim, with equivalent or superior efficacy
- Must be injected at least 24 hours after the end of chemotherapy, and must not be given in the 14 days before the next cycle
- The most common side effect is bone pain, typically appearing 1–3 days after injection and usually manageable with paracetamol, NSAIDs, or in some cases prophylactic loratadine
- Requires refrigerated storage at 2–8°C but may be kept at room temperature (up to 25°C) for a single period of up to 72 hours before use
What Is Pelmeg and What Is It Used For?
Pelmeg belongs to the pharmacotherapeutic class of immunostimulants known as colony-stimulating factors, specifically the long-acting granulocyte colony-stimulating factors (G-CSF). Its active substance, pegfilgrastim, is a covalent conjugate of recombinant human methionyl G-CSF (filgrastim) and a single 20 kilodalton polyethylene glycol (PEG) molecule. This chemical modification—called PEGylation—dramatically reduces the renal clearance of the protein and gives rise to a self-regulating clearance mechanism driven by the neutrophils themselves. The result is a significantly extended serum half-life that allows a single subcutaneous injection to provide neutrophil support for an entire chemotherapy cycle.
Pelmeg is classified as a biosimilar, meaning it has been developed to be highly similar to an already authorized biological reference product (Neulasta). Biosimilar medicines undergo rigorous analytical, non-clinical, and clinical comparability studies before regulatory approval. The European Medicines Agency (EMA) granted marketing authorization for Pelmeg on the basis of physicochemical, biological, pharmacokinetic, pharmacodynamic, and clinical equivalence data demonstrating no clinically meaningful differences from the reference pegfilgrastim in quality, safety, or efficacy. Biosimilars such as Pelmeg play an important role in expanding patient access to G-CSF supportive care by reducing costs for healthcare systems.
Neutrophils are the most abundant type of white blood cell in the human body and act as the first line of defense against bacterial and fungal infections. Many cytotoxic chemotherapy regimens cause myelosuppression, a reduction in the bone marrow's capacity to produce blood cells, leading to neutropenia. When the absolute neutrophil count (ANC) falls below 0.5 × 109/L and is accompanied by fever above 38.3°C (or sustained above 38.0°C), the condition is called febrile neutropenia. This is a medical emergency, because neutropenic patients are at substantial risk of life-threatening bacteremia, sepsis, and organ dysfunction. Pegfilgrastim-based prophylaxis reduces both the depth and the duration of the neutrophil nadir, thereby decreasing the probability that febrile neutropenia will occur.
Approved Indication
Pelmeg is authorized for the reduction in the duration of neutropenia and the incidence of febrile neutropenia in adult patients treated with cytotoxic chemotherapy for malignancy, with the exception of chronic myeloid leukemia (CML) and myelodysplastic syndromes (MDS). The exclusion of CML and MDS reflects the fact that in these myeloid malignancies, G-CSF stimulation could theoretically promote the proliferation of the underlying leukemic clone.
Clinical Pharmacology and Mechanism of Action
Like endogenous G-CSF, pegfilgrastim binds to the G-CSF receptor (G-CSFR, CSF3R) expressed on neutrophil precursor cells in the bone marrow. Receptor binding triggers a cascade of intracellular signaling events—including activation of the JAK2-STAT3, Ras-MAPK, and PI3K-Akt pathways—which promote the proliferation, differentiation, maturation, and functional activation of neutrophils, including their release from the bone marrow into the peripheral blood.
The 20 kDa PEG moiety attached to the N-terminus of filgrastim does not affect receptor binding or biological potency but profoundly alters pharmacokinetics. Renal clearance, which is the dominant elimination pathway for unmodified filgrastim, becomes negligible for pegfilgrastim. Instead, the molecule is cleared primarily by a neutrophil-mediated mechanism: pegfilgrastim binds to G-CSFR on circulating neutrophils and is internalized and degraded along with the receptor. This means that when the neutrophil count is low (for example, during the chemotherapy-induced nadir), pegfilgrastim clearance is low and its serum levels remain high; as the neutrophil count recovers, clearance accelerates and pegfilgrastim levels fall. This self-regulating pharmacokinetic profile is the mechanistic basis for the once-per-cycle dosing schedule.
Clinical Evidence
The clinical efficacy of pegfilgrastim was established in two pivotal phase III randomized controlled trials in women receiving dose-dense chemotherapy for metastatic breast cancer, in which a single injection of pegfilgrastim per cycle was compared with daily filgrastim for 10–14 days. Both trials demonstrated at least equivalent efficacy of pegfilgrastim in reducing the duration of severe neutropenia. A subsequent trial in patients receiving doxorubicin and docetaxel showed that primary prophylaxis with pegfilgrastim reduced the incidence of febrile neutropenia from 17% to 1%, a 94% relative reduction. These findings have been confirmed by multiple meta-analyses and by real-world evidence across diverse chemotherapy regimens.
Professional society guidelines—including those from the American Society of Clinical Oncology (ASCO), the European Society for Medical Oncology (ESMO), the European Organisation for Research and Treatment of Cancer (EORTC), and the National Comprehensive Cancer Network (NCCN)—recommend primary prophylaxis with G-CSF when the anticipated risk of febrile neutropenia from a chemotherapy regimen exceeds approximately 20%, and considered for regimens with intermediate risk (10–20%) in patients with additional risk factors such as age over 65, poor performance status, prior chemotherapy or radiotherapy, pre-existing neutropenia, bone marrow involvement by tumor, or significant comorbidities.
What Should You Know Before Taking Pelmeg?
A careful pre-treatment assessment is essential before initiating Pelmeg. Your oncology team will review your complete medical history, current medications, allergies, and laboratory values. The following information is important both for deciding whether pegfilgrastim is appropriate and for determining the monitoring plan during treatment.
Contraindications
Pelmeg is contraindicated in patients with a history of hypersensitivity to pegfilgrastim, to filgrastim, to any of the excipients, or to proteins derived from Escherichia coli. Serious hypersensitivity reactions, including rare cases of anaphylaxis, have been reported with G-CSF products. Any patient who experiences a serious hypersensitivity reaction should not be re-exposed to pegfilgrastim or any other G-CSF.
Pelmeg must not be used to increase the dose-intensity of cytotoxic chemotherapy beyond regimens that have been established as safe. G-CSF products reduce hematologic toxicity but do not mitigate non-myeloid toxicities such as cardiac, pulmonary, neurological, renal, or gastrointestinal effects. Using G-CSF to support dose-escalation above validated regimens may therefore result in increased non-hematological harm without offsetting benefit.
Warnings and Precautions
Several important safety warnings apply to pegfilgrastim and should be carefully considered by both patients and prescribers:
- Splenic rupture: Splenomegaly and rare cases of splenic rupture, including fatal events, have been reported after pegfilgrastim administration. Any patient who develops left upper abdominal pain or left shoulder tip pain should be urgently evaluated for splenic enlargement or rupture.
- Acute respiratory distress syndrome (ARDS): Pulmonary infiltrates, interstitial pneumonia, and ARDS have been reported and may be fatal. Patients who develop new pulmonary signs or symptoms (fever, cough, dyspnea, tachypnea) should be evaluated promptly, and pegfilgrastim should be discontinued if ARDS is diagnosed.
- Sickle cell crisis: Severe, and sometimes fatal, sickle cell crises have occurred in patients with sickle cell trait or sickle cell disease receiving G-CSF. Extreme caution is required; the benefit must be weighed carefully against the significant risk.
- Capillary leak syndrome: Episodes of capillary leak syndrome—characterized by hypotension, hypoalbuminemia, edema, and hemoconcentration—have been reported. This is a life-threatening condition requiring urgent hospitalization and intensive supportive care.
- Glomerulonephritis: Glomerulonephritis has been reported in patients receiving pegfilgrastim. Cases typically resolve after dose reduction or discontinuation. Urinalysis monitoring is advisable if renal signs develop.
- Aortitis: Inflammation of the aorta (aortitis) has been reported very rarely with G-CSF therapy, usually within 2 weeks of the first dose. Signs include fever, abdominal or back pain, and elevated inflammatory markers. Discontinue pegfilgrastim if aortitis is suspected.
In addition to the serious warnings above, pegfilgrastim is associated with a transient leukocytosis. White blood cell counts of 100 × 109/L or greater have been observed in fewer than 1% of patients and are usually reversible upon discontinuation. Routine complete blood counts, including a platelet count, are recommended at regular intervals during treatment. Thrombocytopenia has been reported; the platelet count should be monitored particularly in patients who have received prior dose-intense chemotherapy.
There have been isolated reports of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) in patients with breast and lung cancer who received pegfilgrastim together with chemotherapy and/or radiotherapy. The causal contribution of pegfilgrastim is difficult to determine because these patients received regimens that are themselves known to increase the risk of secondary malignancies. Nevertheless, patients receiving long-term pegfilgrastim should be counseled about this potential risk.
Patients with acute myeloid leukemia should not receive pegfilgrastim as primary prophylaxis unless specifically indicated in a defined clinical context, because G-CSF receptors may be expressed on the leukemic cells. Similarly, safety and efficacy have not been established in patients with chronic myeloid leukemia or myelodysplastic syndrome, and Pelmeg is not indicated in these populations.
Special Populations
Elderly patients do not require a dose adjustment. Clinical data indicate similar efficacy and safety in patients over 65 years compared with younger adults, although elderly patients may be more vulnerable to certain side effects such as musculoskeletal pain or fatigue.
Renal impairment: No dose adjustment is required in patients with mild, moderate, or severe renal impairment, because renal excretion is not the primary clearance pathway for pegfilgrastim.
Hepatic impairment: No specific studies have been conducted in patients with hepatic impairment. Pharmacokinetic modeling and clinical experience suggest that dose adjustment is not required.
Pediatric population: The safety and efficacy of Pelmeg in children and adolescents below 18 years of age have not been established for the approved indication. Data on use in pediatric oncology are limited and should be considered within specialized protocols only.
Pregnancy and Breastfeeding
There are limited data on the use of pegfilgrastim in pregnant women. Animal reproduction studies have shown reproductive toxicity, including embryo-fetal loss and reduced fetal weight at doses substantially higher than the human therapeutic dose. Pegfilgrastim is not recommended during pregnancy or in women of childbearing potential who are not using effective contraception, unless the potential benefit clearly outweighs the potential risk to the fetus. Any decision should be made in consultation with the treating oncologist.
It is unknown whether pegfilgrastim or its metabolites are excreted in human breast milk. A risk to the breastfed infant cannot be excluded. A decision must be made whether to discontinue breastfeeding or to discontinue Pelmeg therapy, taking into account the benefit of breastfeeding for the child and the benefit of therapy for the mother.
Fertility
No human data on fertility are available. Animal studies have not shown harmful effects on fertility in male or female rats at doses up to 1000 µg/kg per day.
How Does Pelmeg Interact with Other Drugs?
Because pegfilgrastim is a large protein molecule that is cleared by receptor-mediated mechanisms rather than by hepatic metabolism, classical cytochrome P450 (CYP)-mediated drug-drug interactions are not expected. The clinically relevant interactions with pegfilgrastim are therefore pharmacodynamic—that is, related to the effect of other drugs on myeloid cell proliferation, neutrophil function, or overall clinical status—rather than pharmacokinetic.
The most critical interaction, and the reason for strict timing rules, is with cytotoxic chemotherapy itself. Rapidly dividing myeloid progenitors that are stimulated by pegfilgrastim are particularly sensitive to the cytotoxic effects of antineoplastic agents. Administering pegfilgrastim during or immediately after chemotherapy could therefore paradoxically worsen myelosuppression by exposing a larger pool of proliferating cells to cytotoxic injury. For this reason, pegfilgrastim must be administered no earlier than 24 hours after the completion of cytotoxic chemotherapy, and no later than approximately 14 days before the next cycle.
Major Interactions
| Interacting Drug / Class | Effect | Clinical Recommendation |
|---|---|---|
| Cytotoxic chemotherapy (all classes) | Administration during chemotherapy may enhance myelosuppression because expanded myeloid progenitors are more vulnerable to cytotoxic injury | Administer Pelmeg at least 24 hours after the last dose of chemotherapy in each cycle; do not give in the 14 days preceding the next cycle |
| 5-Fluorouracil (5-FU) and capecitabine | S-phase specific cytotoxicity; concurrent administration may lead to severe neutropenia rather than protection | Strict 24-hour separation required; consult oncology pharmacy for regimen-specific timing |
| Bleomycin | Theoretical potentiation of pulmonary toxicity; case reports of pneumonitis in patients receiving G-CSF with bleomycin-containing regimens | Monitor pulmonary symptoms closely; consider risk-benefit individually; obtain baseline and periodic pulmonary function tests when clinically warranted |
| Radiotherapy to large bone marrow fields | Simultaneous G-CSF administration with concurrent chemoradiation has been associated with increased toxicity in some tumor settings | Avoid pegfilgrastim during concurrent chemoradiotherapy unless supported by specific clinical evidence; consult radiation oncologist |
Minor Interactions
| Interacting Drug | Effect | Clinical Recommendation |
|---|---|---|
| Lithium | Lithium promotes the release of neutrophils and may amplify the pharmacodynamic effect of pegfilgrastim on the white blood cell count | Monitor white blood cell counts more frequently when used concurrently; no dose adjustment specifically required |
| Corticosteroids | Corticosteroids can cause neutrophilia through demargination and may confound interpretation of the white blood cell response | Account for corticosteroid-induced neutrophilia when interpreting blood counts; adjust monitoring timing accordingly |
| Imaging agents for bone scans | Increased hematopoietic activity due to G-CSF can produce transient positive findings on bone imaging, potentially mimicking metastatic disease | Inform radiologists of recent pegfilgrastim administration when reviewing bone scintigraphy results |
| Live vaccines | Immunocompromised state during chemotherapy may reduce vaccine efficacy and increase risk of disseminated infection with live vaccines | Avoid live attenuated vaccines during chemotherapy and for a period after completion as advised by the oncology team |
Always provide your healthcare team with a complete medication list including prescription drugs, over-the-counter medicines, herbal products, and dietary supplements before starting Pelmeg. This is especially important when traveling or receiving care from multiple providers, as the close timing rules relative to chemotherapy must be preserved across all care settings.
What Is the Correct Dosage of Pelmeg?
Pelmeg is designed for once-per-cycle dosing, which is one of its principal clinical advantages over conventional filgrastim. Dosing is not adjusted based on body weight, renal function, or hepatic function for the authorized indication in adults. The dose and timing described below are based on the EMA Summary of Product Characteristics (SmPC) and are consistent with international guidelines from ASCO, ESMO, EORTC, and NCCN.
Adults
Standard Adult Dose — Chemotherapy-Induced Neutropenia Prophylaxis
The recommended dose is 6 mg (one pre-filled syringe) administered as a single subcutaneous injection once per chemotherapy cycle. The dose should be given approximately 24 hours after the completion of cytotoxic chemotherapy. Pelmeg must not be administered in the period between 14 days before and 24 hours after the administration of cytotoxic chemotherapy. Common injection sites include the thigh, abdomen (avoiding the 5 cm area around the navel), and the upper outer arm. Sites should be rotated between cycles.
Safety Considerations by Body Weight
No dose adjustment is required based on body weight in adults. The 6 mg dose has been shown to be effective across the full range of adult body weights encountered in clinical practice. The self-regulating pharmacokinetics of pegfilgrastim provide an automatic adjustment of exposure as neutrophils recover.
Children and Adolescents
The safety and efficacy of pegfilgrastim in children under 18 years of age have not been established for the authorized indication, and Pelmeg is not recommended for use in this age group. Some specialized pediatric oncology centers may use pegfilgrastim off-label, typically at a weight-based dose of 100 µg/kg (maximum 6 mg), but this falls outside the scope of the marketing authorization and should only be undertaken in the context of specialist supervision or clinical trials. Parents and caregivers should have a detailed discussion with the pediatric oncology team about any off-label use.
Elderly
No dose adjustment is required for patients aged 65 years and older. Clinical trials have demonstrated comparable efficacy and a broadly similar safety profile in elderly patients, although age-related vulnerability to musculoskeletal pain, fatigue, and bone-related adverse events should be kept in mind.
Renal Impairment
No dose adjustment is recommended in patients with any degree of renal impairment, including end-stage renal disease, because renal clearance is not the dominant elimination pathway for pegfilgrastim. Clinical experience in patients on dialysis is limited but has not identified new safety signals.
Hepatic Impairment
No dedicated studies have been conducted in patients with hepatic impairment. Based on the mechanism of clearance, dose adjustment is not anticipated to be required.
Method of Administration
Pelmeg is administered as a subcutaneous injection using the provided pre-filled syringe with needle safety device. Before injection, remove the syringe from the refrigerator and allow it to reach room temperature for approximately 30 minutes to reduce discomfort at the injection site. Visually inspect the solution: it should be clear and colorless. Do not use if the solution is cloudy, contains visible particles, or is discolored. Do not shake the syringe vigorously. After injection, dispose of the syringe in a sharps container and do not recap the needle. Patients and caregivers who self-administer Pelmeg at home should receive comprehensive training from a healthcare professional, including aseptic technique, injection technique, site rotation, and safe disposal.
Missed Dose
Because Pelmeg is administered only once per chemotherapy cycle, there is no weekly or daily dosing schedule to miss. However, if the planned post-chemotherapy injection is not administered on the expected day (typically day 2 of the cycle), contact your oncology team immediately. Delayed administration may still provide neutrophil support, but the protection may be reduced if the injection is given more than 72 hours after the end of chemotherapy. Do not self-administer a second dose within the same cycle to compensate for a perceived missed dose.
Overdose
There is limited clinical experience with pegfilgrastim overdose. Single doses up to 300 µg/kg have been administered without toxic effects in a small number of healthy volunteers and patients. In case of overdose, the white blood cell count should be monitored closely, and any resulting symptoms of leukocytosis—including bone pain, splenic enlargement, or hyperviscosity—should be managed symptomatically. There is no specific antidote. In the rare event of marked leukocytosis with clinical symptoms, leukapheresis may be considered, but this is seldom required because white blood cell counts spontaneously return to baseline over 1–2 weeks after pegfilgrastim exposure.
If you have been prescribed Pelmeg for home use, remember to: (1) store the syringe in the refrigerator until needed; (2) allow 30 minutes at room temperature before injection for comfort; (3) check the solution is clear and colorless; (4) rotate injection sites between cycles (thigh, abdomen, or upper arm); (5) never reuse a syringe and dispose of sharps safely; (6) record the injection date and site in your treatment diary; and (7) contact your oncology team if you experience unusual symptoms such as left upper abdominal pain, breathing difficulty, or severe allergic reactions.
What Are the Side Effects of Pelmeg?
The safety profile of pegfilgrastim has been extensively characterized through more than two decades of worldwide clinical use and through pooled data from randomized controlled trials and post-marketing surveillance. Most adverse reactions are mild to moderate in severity and transient in nature. The following frequency categories follow the MedDRA convention used in EU SmPCs. It is important to recognize that distinguishing pegfilgrastim-related effects from those caused by chemotherapy or by the underlying malignancy can be challenging in clinical practice.
Very Common
Affects more than 1 in 10 patients (>10%)
- Musculoskeletal pain (bone pain, back pain, arthralgia, myalgia, pain in extremities, neck pain)
- Headache
- Nausea
- Thrombocytopenia (in patients also receiving chemotherapy)
- Leukocytosis (transient increase in white blood cells)
- Elevated lactate dehydrogenase (LDH), alkaline phosphatase, and uric acid
Common
Affects 1 to 10 in 100 patients (1–10%)
- Injection site reactions (pain, erythema, swelling)
- Non-cardiac chest pain
- Dyspepsia, diarrhea, abdominal pain
- Fatigue and asthenia
- Pyrexia (fever)
- Splenomegaly (enlargement of the spleen)
Uncommon
Affects 1 to 10 in 1,000 patients (0.1–1%)
- Hypersensitivity reactions (skin rash, urticaria)
- Cutaneous vasculitis and Sweet syndrome (acute febrile neutrophilic dermatosis)
- Pulmonary adverse events (cough, dyspnea)
- Proteinuria, hematuria
- Injection site induration
- Sickle cell crisis (in patients with sickle cell disease or trait)
Rare / Very Rare
Affects fewer than 1 in 1,000 patients (<0.1%)
- Splenic rupture (potentially fatal — seek urgent medical care for left upper abdominal or shoulder tip pain)
- Acute respiratory distress syndrome (ARDS) and interstitial pneumonia
- Capillary leak syndrome (hypotension, hypoalbuminemia, edema, hemoconcentration)
- Glomerulonephritis
- Aortitis (inflammation of the aorta, typically within 2 weeks of first dose)
- Anaphylaxis and other severe hypersensitivity reactions
- Stevens-Johnson syndrome (very rare)
Bone pain is the most characteristic and most frequently reported side effect of pegfilgrastim, affecting up to 30–40% of patients to some degree. It typically develops 1–3 days after the injection and reflects the expansion of the bone marrow as it produces increased numbers of neutrophils. The pain most commonly affects the lower back, pelvis, sternum, ribs, and long bones. It is usually mild to moderate and self-limiting, resolving within a few days. Management strategies include:
- Paracetamol (acetaminophen): First-line analgesic, 500–1000 mg every 4–6 hours as needed (max 4 g/day)
- Non-steroidal anti-inflammatory drugs (NSAIDs): Such as ibuprofen or naproxen, provided there are no contraindications (e.g., thrombocytopenia, renal impairment, active peptic ulcer)
- Loratadine or other second-generation H1 antihistamines: Emerging evidence suggests that prophylactic loratadine 10 mg daily for 5–7 days starting on the day of pegfilgrastim may reduce the incidence and intensity of bone pain
- Non-pharmacological measures: Gentle exercise, warm compresses, adequate hydration
Severe or escalating bone pain should be evaluated by the oncology team to exclude other causes.
If you experience any side effects, including those not listed above, please inform your doctor, nurse, or pharmacist. You can also report suspected adverse reactions directly to your national pharmacovigilance authority (for example, the MHRA Yellow Card Scheme in the UK, the FDA MedWatch system in the US, or the EudraVigilance system in the EU). Reporting side effects helps improve the safety profile knowledge of this medicine.
How Should You Store Pelmeg?
Pegfilgrastim is a protein-based biological medicine, and correct storage is essential to preserve its structural integrity and clinical efficacy. Deviations from the recommended storage conditions can lead to protein denaturation, aggregation, or loss of potency, with potential impact on both efficacy and immunogenicity.
Pelmeg pre-filled syringes must be stored in a refrigerator at 2–8°C (36–46°F). Do not freeze. Accidental exposure to freezing temperatures for a single period of less than 24 hours has been shown not to adversely affect product stability, but repeated or prolonged freezing is not permitted and any syringe that has been frozen more than once or for longer than 24 hours should be discarded. Keep the pre-filled syringe in the outer carton in order to protect the product from light.
For patient convenience and to facilitate home administration, Pelmeg may be removed from the refrigerator and stored at room temperature (not above 25°C / 77°F) for a single continuous period of up to 72 hours. If the product is not used within this 72-hour period at room temperature, it must be discarded. Do not return the product to the refrigerator after it has been stored at room temperature; repeated temperature cycling may compromise stability.
Keep Pelmeg out of the sight and reach of children. Do not use Pelmeg after the expiry date shown on the carton and the syringe label. The expiry date refers to the last day of that month. Before injection, perform a visual inspection of the solution: it should be a clear, colorless liquid. Do not use the solution if it is cloudy, if you see particles or discoloration, or if the syringe has any visible damage. Do not shake the syringe vigorously, as this can cause protein aggregation and loss of activity.
Dispose of used syringes and needles in an approved sharps container, following local regulations for biohazardous medical waste. Do not dispose of syringes in household waste. Ask your pharmacist how to dispose of medicines you no longer need; this helps protect the environment and prevents accidental injuries.
What Does Pelmeg Contain?
Knowing the complete composition of Pelmeg is important for identifying potential allergens and for understanding the pharmaceutical characteristics of the product. All components have been chosen to maintain the stability and biological activity of the pegylated protein throughout its shelf life.
Active Substance
Each pre-filled syringe contains 6 mg of pegfilgrastim in 0.6 mL of solution, corresponding to a concentration of 10 mg/mL. Pegfilgrastim is a covalent conjugate of recombinant human methionyl granulocyte colony-stimulating factor (filgrastim, r-metHuG-CSF) produced in genetically modified Escherichia coli by recombinant DNA technology, and a single 20 kilodalton (kDa) monomethoxypolyethylene glycol (mPEG) molecule attached at the N-terminal methionine residue. The protein component of pegfilgrastim consists of 175 amino acids and has a molecular weight of approximately 18.8 kDa; the total molecular weight of the PEGylated conjugate is approximately 39 kDa.
Excipients
The inactive ingredients serve to stabilize the protein, buffer the pH of the solution, adjust tonicity, and prevent surface-mediated protein aggregation:
- Sodium acetate: A buffering agent that maintains the solution at approximately pH 4.0, which is the optimal pH for long-term stability of pegfilgrastim
- Sorbitol (E420): A tonicity-adjusting agent and stabilizer. Patients with hereditary fructose intolerance should not receive pegfilgrastim because sorbitol is metabolized to fructose
- Polysorbate 20: A non-ionic surfactant that prevents adsorption of the protein to container surfaces and reduces the risk of aggregation during storage and transport
- Water for injections: The solvent
The product may also contain small amounts of sodium hydroxide or glacial acetic acid used for pH adjustment during manufacturing. Pelmeg contains less than 1 mmol of sodium (23 mg) per 6 mg dose, which means it is essentially sodium-free.
Pelmeg does not contain preservatives. Each pre-filled syringe is intended for single use only, and any unused portion should be discarded appropriately. The needle shield of the pre-filled syringe is latex-free, making Pelmeg suitable for use in patients with known natural rubber latex allergy.
Frequently Asked Questions About Pelmeg
Pelmeg is a biosimilar medicine containing pegfilgrastim, a long-acting granulocyte colony-stimulating factor (G-CSF). It is used in adults to reduce the duration of severe neutropenia and the incidence of febrile neutropenia caused by cytotoxic chemotherapy for malignancy (except chronic myeloid leukemia and myelodysplastic syndromes). A single 6 mg subcutaneous injection per chemotherapy cycle is given approximately 24 hours after the end of chemotherapy, replacing multiple daily filgrastim injections and reducing the risk of dangerous infections during the neutrophil nadir.
Pelmeg is given as a single 6 mg subcutaneous (under the skin) injection using the provided pre-filled syringe. The injection should be administered approximately 24 hours after the end of each chemotherapy cycle; it must not be given within 24 hours before or after chemotherapy, and not within 14 days before the next cycle. Typical injection sites are the thigh, abdomen (avoiding the area around the navel), or upper outer arm. With appropriate training from a healthcare professional, patients or caregivers can self-administer Pelmeg at home. Bring the syringe to room temperature for about 30 minutes before injection to improve comfort.
Pelmeg contains pegfilgrastim, which is filgrastim that has been modified by attachment of a 20 kDa polyethylene glycol (PEG) molecule. The PEG greatly reduces renal clearance and creates a self-regulating neutrophil-mediated clearance mechanism: when neutrophils are low (during the chemotherapy nadir), clearance is low and exposure is prolonged; when neutrophils recover, clearance accelerates. This pharmacokinetic profile allows a single 6 mg injection to cover an entire chemotherapy cycle, compared with 10–14 daily injections of filgrastim. Clinical trials and meta-analyses have shown pegfilgrastim to be at least as effective as daily filgrastim in reducing the duration of severe neutropenia and the incidence of febrile neutropenia.
The most common side effect is musculoskeletal pain—particularly bone pain and back pain—which occurs in more than 1 in 10 patients and reflects the bone marrow expansion that is part of the therapeutic effect. Headache, nausea, and injection site reactions are also common. Bone pain typically starts 1–3 days after injection and is usually mild to moderate. It can generally be managed with paracetamol (acetaminophen), NSAIDs such as ibuprofen (if not contraindicated), adequate hydration, and gentle activity. Emerging evidence suggests that prophylactic loratadine 10 mg daily for 5–7 days starting on the day of pegfilgrastim may reduce the intensity of bone pain. Severe or persistent pain should be reported to the oncology team.
Yes. Pelmeg is an EMA-approved biosimilar of the reference pegfilgrastim product Neulasta. Biosimilars are biological medicines that have been shown through extensive analytical, non-clinical, and clinical comparability studies to be highly similar to the reference product, with no clinically meaningful differences in quality, safety, or efficacy. Pelmeg underwent rigorous comparability testing before approval, and can be used in the same indication and at the same dose as the reference product. Switching between biosimilars and reference products is considered safe and appropriate under the guidance of a qualified prescriber.
Pelmeg is not recommended during pregnancy. There are limited data from use in pregnant women, and animal studies have shown reproductive toxicity (embryo-fetal loss and reduced fetal weight) at high doses. Women of childbearing potential should use effective contraception during treatment and for a period afterwards as advised by the oncology team. It is unknown whether pegfilgrastim or its metabolites pass into human breast milk, so breastfeeding is not recommended during treatment with Pelmeg. Any decision should be individualized and made jointly with the treating oncologist, taking into account the urgency of chemotherapy, the risk to the pregnancy, and the availability of alternatives.
Store Pelmeg in a refrigerator at 2–8°C in its original carton, which protects it from light. Do not freeze; however, a single accidental exposure to temperatures below zero for less than 24 hours does not adversely affect stability. If the syringe has been frozen more than once or for longer than 24 hours, it should be discarded. Pelmeg may be removed from the refrigerator and kept at room temperature (not above 25°C) for a single continuous period of up to 72 hours; if not used in that time, the syringe must be discarded and not returned to the refrigerator. Before injection, inspect the solution: it should be clear and colorless without particles.
References
This article is based on the following peer-reviewed sources and international guidelines:
- European Medicines Agency (EMA). Pelmeg – Summary of Product Characteristics (SmPC) and European Public Assessment Report (EPAR). EMA/CHMP, current version. Available at: www.ema.europa.eu
- Smith TJ, Bohlke K, Lyman GH, et al. Recommendations for the Use of WBC Growth Factors: American Society of Clinical Oncology Clinical Practice Guideline Update. Journal of Clinical Oncology. 2015;33(28):3199–3212.
- Aapro MS, Bohlius J, Cameron DA, et al. 2010 update of EORTC guidelines for the use of granulocyte-colony stimulating factor to reduce the incidence of chemotherapy-induced febrile neutropenia in adult patients with lymphoproliferative disorders and solid tumours. European Journal of Cancer. 2011;47(1):8–32.
- Vogel CL, Wojtukiewicz MZ, Carroll RR, et al. First and subsequent cycle use of pegfilgrastim prevents febrile neutropenia in patients with breast cancer: a multicenter, double-blind, placebo-controlled phase III study. Journal of Clinical Oncology. 2005;23(6):1178–1184.
- Holmes FA, O'Shaughnessy JA, Vukelja S, et al. 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. Journal of Clinical Oncology. 2002;20(3):727–731.
- Klastersky J, de Naurois J, Rolston K, et al. Management of febrile neutropenia: ESMO Clinical Practice Guidelines. Annals of Oncology. 2016;27(suppl 5):v111–v118.
- National Comprehensive Cancer Network (NCCN). Clinical Practice Guidelines in Oncology: Hematopoietic Growth Factors. Version 1.2025.
- Weise M, Bielsky MC, De Smet K, et al. Biosimilars: what clinicians should know. Blood. 2012;120(26):5111–5117.
- Kuderer NM, Dale DC, Crawford J, Lyman GH. Impact of primary prophylaxis with granulocyte colony-stimulating factor on febrile neutropenia and mortality in adult cancer patients receiving chemotherapy: a systematic review. Journal of Clinical Oncology. 2007;25(21):3158–3167.
- Pinto L, Liu Z, Doan Q, Bernal M, Dubois R, Lyman G. Comparison of pegfilgrastim with filgrastim on febrile neutropenia, grade IV neutropenia and bone pain: a meta-analysis of randomized controlled trials. Current Medical Research and Opinion. 2007;23(9):2283–2295.
- British National Formulary (BNF). Pegfilgrastim. NICE Evidence Services, current edition. Available at: bnf.nice.org.uk
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List (2023). Geneva: WHO; 2023.
- Kirshner JJ, Heckler CE, Janelsins MC, et al. Prevention of pegfilgrastim-induced bone pain: a phase III double-blind placebo-controlled randomized clinical trial of the University of Rochester Cancer Center Clinical Community Oncology Program research base. Journal of Clinical Oncology. 2012;30(16):1974–1979.
Editorial Team
This article was written and reviewed by the iMedic Medical Editorial Team, composed of licensed specialist physicians with expertise in clinical pharmacology, medical oncology, and hematology.
iMedic Medical Editorial Team — specialists in clinical pharmacology, oncology, and hematology with documented academic background and clinical experience in chemotherapy supportive care and the management of febrile neutropenia.
iMedic Medical Review Board — independent panel of medical experts reviewing all content against international guidelines (WHO, EMA, FDA, ASCO, ESMO, EORTC, NCCN) using the GRADE evidence framework.
Evidence standard: All medical claims in this article are supported by evidence level 1A (systematic reviews and meta-analyses of randomized controlled trials) or current international clinical practice guidelines. This content has no commercial funding and is free from pharmaceutical industry influence.