Macrophage activator (MTP-PE) Pregnancy: eMC §4.6: there are no data from the use of mifamurtide in pregnant women and animal studies are insufficient with respect to reproductive toxicity. Mifamurtide is not recommended for use during pregnancy or in women of childbearing potential not using effective contraception. Breast-feeding: it is unknown whether mifamurtide is excreted in human milk and excretion in milk has not been studied in animals — a decision to continue or discontinue breast-feeding or therapy should weigh the benefit of breast-feeding to the child against the benefit of therapy to the woman. Fertility: no dedicated fertility studies have been conducted.

Mifamurtide (Specialist drug)

Brand names: Mepact

Mifamurtide is an immunostimulant used, under specialist supervision, as an adjunct to chemotherapy after surgery for high-grade resectable non-metastatic osteosarcoma.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 2 mg/m2 body surface area per infusion (the recommended dose for all patients)

Route: Intravenous infusion over a period of 1 hour. Mifamurtide must NOT be administered as a bolus injection.

Frequency: As adjuvant therapy following resection: twice weekly, at least 3 days apart, for 12 weeks; then once weekly for a further 24 weeks — a total of 48 infusions over 36 weeks

eMC SPC (Mifamurtide 4 mg powder for concentrate for dispersion for infusion) §4.2: 'The recommended dose of mifamurtide for all patients is 2 mg/m2 body surface area. It should be administered as adjuvant therapy following resection: twice weekly at least 3 days apart for 12 weeks, followed by once-weekly treatments for an additional 24 weeks for a total of 48 infusions in 36 weeks.' Treatment should be initiated and supervised by specialist physicians experienced in the diagnosis and treatment of osteosarcoma. Reconstitute, filter using the filter provided, and dilute before administration as directed in §6.6. PAEDIATRIC (the dose is per m2 body surface area, not per kg, so it is not captured in the structured paedDose field): the same 2 mg/m2 dose applies to all patients; safety and efficacy in children aged 0 to 2 years have not been established and no data are available. Verify any paediatric use against a children's formulary and the local protocol. ADULTS OVER 30 YEARS: none of the patients treated in the osteosarcoma studies were 65 years or older, and the phase III randomised study included only patients up to 30 years of age — there are not sufficient data to recommend use in patients over 30 years of age. HEPATIC IMPAIRMENT: no dose adjustment is necessary for Child-Pugh class A or B, but caution is recommended in moderate hepatic impairment because pharmacokinetic variability is greater and safety data are limited; no pharmacokinetic data are available in severe hepatic impairment, so caution is recommended. Continued monitoring of kidney and liver function is recommended if mifamurtide is used beyond completion of chemotherapy until all therapy is completed. MONITORING AND PRECAUTIONS (§4.4): consider prophylactic bronchodilators in patients with a history of asthma or other chronic obstructive pulmonary disease, and discontinue if a severe respiratory reaction occurs; mifamurtide may be given during periods of neutropenia, but fever or chills persisting more than 8 hours after administration should be evaluated for possible sepsis; use with caution in patients with a history of autoimmune, inflammatory or other collagen disease and monitor for arthritis or synovitis suggesting an uncontrolled inflammatory reaction; closely monitor patients with a history of venous thrombosis, vasculitis or unstable cardiovascular disorders and delay or discontinue if symptoms persist and worsen; monitor clotting parameters after the first dose and again after several doses. NOTE: eMC §4.5 and §4.8 were truncated at the source-fetch limit in the fetched bundle — clinician to verify against the full current SPC.

Dose adjustments

Renal

eMC §4.2: there are no clinically meaningful effects of mild to moderate renal impairment (creatinine clearance >=30 mL/min) on the pharmacokinetics of mifamurtide, so no dose adjustment is necessary for these patients. No pharmacokinetic data are available in severe renal impairment, so caution is recommended when administering mifamurtide to these patients, with continued monitoring of kidney function if used beyond completion of chemotherapy.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients (eMC §4.3)
Concurrent use with ciclosporin or other calcineurin inhibitors (eMC §4.3, see §4.5)
Concurrent use with high-dose non-steroidal anti-inflammatory drugs (NSAIDs, cyclooxygenase inhibitors) (eMC §4.3, see §4.5)

Side effects

Most frequent overall: chills, pyrexia, fatigue, nausea, tachycardia and headache — the majority reported as mild or moderate
Very common: anaemia; anorexia; headache and dizziness; tachycardia; hypertension and hypotension
Very common: dyspnoea, tachypnoea and cough; vomiting, diarrhoea, constipation, abdominal pain and nausea
Very common: hyperhidrosis; myalgia, arthralgia, back pain and pain in extremity
Common: sepsis, cellulitis, catheter site infection and other infections; leukopenia, thrombocytopenia, granulocytopenia, febrile neutropenia; dehydration and hypokalaemia; pleural effusion; rash and pruritus
Uncommon/other: pronounced inflammatory response including pericarditis and pleuritis; allergic reactions including rash, shortness of breath and Grade 4 hypertension; pericardial effusion (frequency not known)

Interactions

Ciclosporin and other calcineurin inhibitors: concurrent use is CONTRAINDICATED (eMC §4.3)
High-dose NSAIDs (cyclooxygenase inhibitors): concurrent use is CONTRAINDICATED (eMC §4.3)
Chemotherapy: limited, non-conclusive interaction studies have been conducted; there is no evidence of interference of mifamurtide with the anti-tumour effects of chemotherapy (eMC §4.5 — the remainder of this section was truncated at the source-fetch limit, so treat the interaction list as incomplete)

Clinical monograph

How it works

It is a synthetic analogue of a bacterial cell-wall component that activates monocytes and macrophages, stimulating an immune response against residual tumour cells.

Prescribing in practice

Infusion-related and systemic inflammatory reactions are common, so it is given as a controlled intravenous infusion with monitoring; it should be avoided in patients with significant respiratory disease such as asthma due to bronchospasm risk.
It should not be given concurrently with high-dose NSAIDs or ciclosporin and other calcineurin inhibitors, which may interfere with its activity.
It is administered within a specialist osteosarcoma protocol alongside combination chemotherapy.

Monitoring

Monitor for infusion reactions, fever, respiratory symptoms and signs of systemic inflammation during and after each infusion.

Counselling the patient

Expect chills, fever and tiredness around infusions; tell the team if they are severe or you become breathless.
Report wheeze or chest tightness, particularly if you have asthma.
Attend all scheduled infusions to complete the planned course.

Evidence & guidelines

Approved as an adjunct in non-metastatic resectable osteosarcoma; use follows NICE and specialist commissioning arrangements.

Reference: NICE TA235; SmPC; Confirm identity and dosing against the manufacturer SPC (eMC) and NICE. Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways