The addition of the immunomodulator mifamurtide to adjuvant chemotherapy for early osteosarcoma: a retrospective analysis

Summary Background . Current treatment recommendations for high grade non-metastatic osteosarcoma include perioperative chemotherapy and surgery. Despite this intensive protocol, approximately 40% of patients will relapse. The addition of the immunomodulator mifamurtide to adjuvant cytotoxic chemotherapy was associated with a significant improvement in 6-year overall survival (OS) in young patients with resectable osteosarcoma, leading to its approval in Europe and other countries. Very limited real-world data are reported on its use. Methods . We retrospectively evaluated data from osteosarcoma patients who received mifamurtide in the adjuvant setting. Data were obtained from medical records in 2 high-volume bone sarcoma centers. The aim of this study was to collect real-world data on mifamurtide safety and efficacy in Greece. Results . We identified 15 patients with completely resected osteosarcoma who received mifamurtide from September 2015 to January 2020. Median age at diagnosis was 24 years old (16–76). Osteosarcoma arose in the lower extremities (n = 12), in the upper extremities (n = 2) or in the ilium (n = 1). The majority of patients (n = 13) received cisplatin/doxorubicin/methotrexate as perioperative chemotherapy and the remaining patients cisplatin/doxorubicin. After a median follow-up of 46.9 months (range, 32.8–61.1), the median recurrence-free survival was 58.7 months (range, 18.5–98.8) and the median OS 64.1 months (range, 25.6–102.6). Except for fever and chills, the only adverse event probably related to mifamurtide was pericarditis (n = 1). Conclusions . Mifamurtide was well tolerated in a Greek osteosarcoma population, including patients older than 30 years. The small sample size and the non-comparative design do not allow drawing conclusions on the drug benefit in terms of survival.