mifamurtide

Mifamurtide, also known as liposomal muramyl tripeptide phosphatidylethanolamine (L-MTP-PE), is an immunotherapy drug used in the treatment of osteosarcoma. It is a macrophage-activating agent formulated as liposomes to deliver the muramyl dipeptide motif to immune cells. By engaging pattern recognition receptors such as NOD2 on macrophages, mifamurtide stimulates cytokine production and enhances innate and adaptive immune responses against tumor cells, supporting cytotoxic activity.

In the European Union, mifamurtide is approved for use in combination with standard chemotherapy for patients with non-metastatic osteosarcoma. It is not approved by the U.S. Food and Drug Administration, and regulatory status varies by country based on assessments of benefit and risk.

Mifamurtide is administered by intravenous infusion, typically on a weekly schedule during chemotherapy cycles. The liposomal formulation is intended to improve delivery to macrophages and to help moderate systemic toxicity.

Common adverse effects include fever, chills, fatigue, headache, and infusion-related reactions. Other possible effects include nausea, rash, and transient elevations in liver enzymes; serious events are uncommon but may include hypotension or severe infections in susceptible individuals.

Clinical trials in osteosarcoma have reported improvements in disease-free survival when mifamurtide is added to standard chemotherapy, though results for overall survival have varied. Regulatory approvals and clinical use continue to reflect regional differences, with ongoing research aimed at clarifying optimal dosing, combinations, and patient selection.