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

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.

Outcomes from a mechanistic biomarker multi-arm and randomised study of liposomal MTP-PE (Mifamurtide) in metastatic and/or recurrent osteosarcoma (EuroSarc-Memos trial).

The phase III clinical study of adjuvant liposomal muramyl tripeptide (MTP-PE) in resected high-grade osteosarcoma (OS) documented positive results that have been translated into regulatory approval, supporting initial promise for innate immune therapies in OS. There remains, however, no new approved treatment such as MTP-PE for either metastatic or recurrent OS. Whilst the addition of different agents, including liposomal MTP-PE, to surgery for metastatic or recurrent high-grade osteosarcoma has tried to improve response rates, a mechanistic hiatus exists in terms of a detailed understanding the therapeutic strategies required in advanced disease. Here we report a Bayesian designed multi-arm, multi-centre, open-label phase II study with randomisation in patients with metastatic and/or recurrent OS, designed to investigate how patients with OS might respond to liposomal MTP-PE, either given alone or in combination with ifosfamide. Despite the trial closing because of poor recruitment within the allocated funding period, with no objective responses in eight patients, we report the design and feasibility outcomes for patients registered into the trial. We demonstrate the feasibility of the Bayesian design, European collaboration, tissue collection with genomic analysis and serum cytokine characterisation. Further mechanistic investigation of liposomal MTP-PE alone and in combination with other agents remains warranted in metastatic OS.

Muramyl Tripeptide-Phosphatidyl Ethanolamine Encapsulated in Liposomes (L-MTP-PE) in the Treatment of Osteosarcoma.

The recruitment of autologous macrophages to attack osteosarcoma represents a novel immunotherapy approach to the treatment of osteosarcoma. Muramyl tripeptide-phosphatidyl ethanolamine encapsulated in liposomes (L-MTP-PE) was derived as a compound with the ability to stimulate macrophages to destroy autologous osteosarcoma tumor cells. Preclinical studies including studies in dogs with spontaneously arising osteosarcoma showed the ability of L-MTP-PE to control microscopic metastatic disease in osteosarcoma. A pivotal clinical trial led to the approval of L-MTP-PE for the treatment of newly diagnosed osteosarcoma in over 40 countries.

Lipopolysaccharide-binding protein expression is associated to the metastatic status of osteosarcoma patients.

Osteosarcoma (OS) is a rare malignant primary bone tumours characterized by a high genetic and cell composition heterogeneity. Unfortunately, despite the use of drug combinations and the recent development of immunotherapies, the overall survival has not improved in the last four decades. Due to the key role of the tumour microenvironment in the pathogenesis of OS, a better understanding of its microenvironment is mandatory to develop new therapeutic approaches. From retrospective biological cohorts of OS, we analysed by immunohistochemistry the presence of lipopolysaccharide (LPS)-binding protein (LBP) in diagnostic biopsies with local disease and compared their level of infiltration to patients suffering from metastatic status. LBP is considered as a marker of LPS exposure and can indirectly reflect the presence of Gram-negative microbiota. LBP were detected in the cytoplasm of OS cells as well as in tumour-associated macrophage. Tumour samples of patients with local disease were significantly enriched in LBP compared to tumour tissues of patients with metastatic status. Lung metastatic tissues showed similar level of LBP compared to paired primary tumours. Overall, this study strongly suggests the presence of Gram-negative bacteria in OS tissues and demonstrated their significant differential level according the metastatic status. This tumour-associated microbiome may help in the conceptualisation of new therapeutic approach to trigger efficient therapeutic responses against cancer.

Current and future therapeutic approaches for osteosarcoma.

INTRODUCTION: Current treatment of osteosarcoma includes surgical resection of all gross disease in conjunction with systemic chemotherapy to control micro-metastatic disease. This yields a 5-year event free survival (EFS) of approximately 70% for patients with localized osteosarcoma while patients with metastatic or recurrent disease fare poorly with overall survival rates of less than 20%. Areas covered: This review outlines the current and future approach towards the treatment of osteosarcoma. A literature search was performed utilizing PubMed. Several recent clinical trials are reviewed in detail, as is innovative research evaluating novel agents and surgical techniques which hold promise. Expert commentary: The outcome for patients with osteosarcoma has not changed in several decades. This plateau in survival rates highlights the need for a novel approach towards research. There remains a great deal of interest in utilizing the very high risk population of recurrent osteosarcoma patients to rapidly and sequentially evaluate novel agents to determine if any of these agents hold promise. Several phase II studies are ongoing or in development that offer hope based on intriguing preclinical data. Furthermore, initiatives in obtaining specimens to further explore the genetic and immunological profile behind osteosarcoma will be essential towards identifying novel pathways and targets to exploit.