Prospectively Planned Analysis of Data From a Phase III Study of Liposomal Muramyltripeptide Phosphatidylethanolamine in the Treatment of Osteosarcoma

Effectiveness of mifamurtide in addition to standard chemotherapy for high-grade osteosarcoma: a systematic review

BACKGROUND

Osteosarcoma mostly occurs during the period of rapid bone growth in children and adolescents as high-grade osteosarcomas. Current treatment recommended for high-grade non-metastatic and metastatic and/or relapsed osteosarcoma involves neoadjuvant multiagent conventional chemotherapy, followed by surgical resection of macroscopically detected tumor and postoperative adjuvant chemotherapy. However, residual micrometastatic deposits that develop following surgery have shown resistance to postoperative/adjuvant chemotherapy. Therefore, there is a critical need for more effective and innovative therapeutic approaches such as immune stimulatory agents. The most extensively studied immune stimulatory agent in the treatment of osteosarcoma is mifamurtide. The aim of this systematic review was to identify and synthesize the evidence on the effectiveness of mifamurtide in addition to standard chemotherapy on survival outcomes.

OBJECTIVES

To present the best available evidence on the treatment of high-grade non-metastatic and metastatic osteosarcoma with mifamurtide in addition to standard chemotherapy.

INCLUSION CRITERIA TYPES OF PARTICIPANTS

All populations of patients regardless of age, gender or ethnicity with high-grade, resectable, non-metastatic and metastatic osteosarcoma based on histological diagnosis.

TYPES OF INTERVENTIONS AND COMPARATORS

This review focused on intravenous infusion of either of the pharmaceutical formulations of mifamurtide (MTP-PE or L-MTP-PE) in addition to standard chemotherapy, and the comparator was chemotherapy alone.

TYPES OF STUDIES

This review considered any experimental study design including randomized controlled trials, non-randomized trials and quasi-experimental studies.

OUTCOMES

The primary outcomes of interest were event-free survival, overall survival and recurrence of osteosarcoma. Secondary outcomes that were considered included health-related quality of life and any mifamurtide-related adverse events.

SEARCH STRATEGY

A search for published and unpublished literature in English was undertaken (seven published literature databases, four unpublished literature databases, and three government agency and organizational websites were searched). Studies published between 1990 to June 2016 were considered. A three-step strategy was developed using MeSH terminology and keywords to ensure that all relevant studies were included related to this review.

METHODOLOGICAL QUALITY

The methodological quality of included studies was assessed by two reviewers, who appraised each study independently, using a standardized Joanna Briggs Institute (JBI) critical appraisal tool.

DATA EXTRACTION

Data was extracted from the studies that were identified as meeting the criteria for methodological quality using the standard JBI data extraction tool.

DATA SYNTHESIS

Due to the heterogeneity of populations and interventions in available studies, meta-analysis was not possible and results are presented in narrative form.

RESULTS

Three papers outlining two studies involving 802 patients evaluated the effectiveness of mifamurtide in addition of chemotherapy. Results indicated no significant difference in event-free survival between the addition of mifamurtide to standard chemotherapy regimen and chemotherapy alone, both in non-metastatic and metastatic osteosarcoma patients. There was a significant difference in progression-free survival favoring the addition of mifamurtide in pulmonary metastatic and/or relapsed osteosarcoma. There was no significant difference in overall survival between the addition of mifamurtide and chemotherapy alone in metastatic osteosarcoma; however there was a significant difference favoring the addition of mifamurtide in non-metastatic osteosarcoma patients. The addition of mifamurtide resulted in a significant difference in survival after relapse in pulmonary metastatic and/or relapsed osteosarcoma patients. Both studies reported on mifamurtide-related adverse events - the first was reported as toxicity which included haematological, hepatic, renal, gastrointestinal disorders, cardiac, rhythm and nervous system disorders, ear disorders and others (infection, fever; and performance status) in metastatic osteosarcoma patients. Results were similar across all combined treatment regimens. Although no statistical analysis was undertaken, the figures suggest there were no significant differences between the treatment regimens. In the other study, mifamurtide-related adverse events were reported as clinical toxic effects of mifamurtide in relapsed osteosarcoma, which included chills, fever and headache for the initial dose of mifamurtide, while for the subsequent doses of mifamurtide all patients reported toxicity as delayed fatigue.

CONCLUSIONS

The available evidence on the effectiveness of mifamurtide in addition to a standard chemotherapy regimen for the treatment of high-grade osteosarcoma is limited and therefore no definitive conclusions can be made.

Liposomal muramyl tripeptide phosphatidyl ethanolamine: a safe and effective agent against osteosarcoma pulmonary metastases

Osteosarcoma is the most common form of primary malignant bone tumor. The use of chemotherapy drugs with many side effects, including high-dose methotrexate, doxorubicin, cisplatin and ifosfamide, has greatly improved osteosarcoma survival compared with surgery alone. However, for 20 years, overall survival remained at a plateau of 60-70% in nonmetastatic disease and 20-30% in metastatic osteosarcoma owing to lung metastases. Liposomal muramyl tripeptide phosphatidyl ethanolamine (L-MTP-PE) is a new agent that improves overall osteosarcoma survival (chemotherapy without L-MTP-PE 70% versus with L-MTP-PE 78%; p = 0.03). L-MTP-PE offers additional benefit for osteosarcoma treatment in combination with chemotherapy, particularly ifosfamide-containing regimens. Clinical experience indicates that side effects such as fever are temporary and controlled or prevented with ibuprofen and/or acetoaminophen premedication; severe side effects are rare. Although surgery will remain the main approach for osteosarcoma treatment of lung metastases, L-MTP-PE combined with other modalities, including chemotherapy, appears to be of benefit in these patients as well.

Management of osteosarcoma

Improving cure rates for osteosarcoma continues to be a major challenge. The clinical management of individual patients is exacting and requires a skilled, experienced team including a surgeon, pathologist, oncologist, and radiologist, with support from specialist nurses and rehabilitation teams. Outcomes from treatment have improved little in 20 years and remain disappointing. Chemotherapy for osteosarcoma is among the most grueling of any given for solid tumors, and treatment of the primary tumor is associated with permanent disability of some degree in a significant proportion of patients. New systemic treatments remain beyond the horizon. In recognition of these difficulties, an international cooperation has begun with the opening of a randomized trial, European and American Osteosarcoma (EURAMOS) 1, in Europe and the United States. This study heralds a new era of clinical investigation into osteosarcoma, with the promise of valuable biologic insights and rapid evaluation of investigational strategies. Osteosarcoma should always be treated under the guidance of a specialist team, and we recommend that whenever possible, patients be offered entry into EURAMOS 1 or other well-designed clinical trials.

Liposomal muramyl tripeptide phosphatidyl ethanolamine: ifosfamide-containing chemotherapy in osteosarcoma

Liposomal muramyl tripeptide phosphatidyl ethanolamine (L-MTP-PE) is a synthetic biological investigational agent used for treating osteosarcoma. It has been used in both canine and human osteosarcoma to reduce pulmonary metastases, the most common pattern of treatment failure for sarcomas. L-MTP-PE has been well tolerated using the concept of biological cancer therapy during chemotherapy. The use of L-MTP-PE with ifosfamide is the best studied combination with single agent chemotherapy. This may represent a new treatment choice for osteosarcoma patients receiving ifosfamide. Such patients include those with a poor initial histological response to primary therapy and/or metastatic disease including pulmonary metastases. Reduction of side effects of L-MTP-PE, such as fever and/or flu-like symptoms, with ibuprofen has not reduced efficacy. Since improved symptom control is possible using drug combinations that are especially effective for delayed nausea, outpatient high-dose ifosfamide chemotherapy combined with L-MTP-PE may lead to a safe and effective therapy while maintaining the patients’ quality of life.