Researchers affiliated with the Children’s Oncology Group have shown that the addition of muramyl tripeptide (MTP) to chemotherapy improves survival in patients with osteosarcoma. The details of this study appeared in the February 1, 2008 issue of the Journal of Clinical Oncology.¹ 

Osteosarcoma is a disease of younger individuals that is treated with surgery, radiation, and chemotherapy. Patients with complete surgical resection receive adjuvant chemotherapy, which has decreased relapse rates and improved survival. Research is still being carried out to determine the optimal chemotherapy regimen.

There have been many attempts during the past five decades to use immune modulators to enhance endogenous immune responses to various cancers, including ostersarcoma. The most common form of non-specific immune stimulation involves Bacille Calmette-Guerin (BCG), which has been evaluated with equivocal results in several cancers. Another approach has been specific vaccines that target tumor cells. For example, Onyvax-105 is an allogeneic osteosarcoma cell vaccine that elicits immune responses. A positive effect on survival, however, has not been demonstrated by Onyvax-105. MTP is a synthetic lipophilic analog of muramyl dipeptide, which is a component of the cell wall of BCG. Laboratory studies have shown that MTP stimulates an immunologic response.

The current study involved 662 patients with osteosarcoma without metastatic disease. All had surgical resection of their disease. One-third of patients were between the ages of 15 and 30 years, and the remainder were younger than 15 years. All patients received adjuvant cisplatin, doxorubicin, and methotrexate and definitive surgery. Patients were randomly allocated to receive or not receive ifosfamide. In a separate randomization, patients were randomly allocated to receive or not receive MTP. The median follow-up of this trial was 7.7 years. The overall relapse rate was 33%. These authors reported that the addition of ifosfamide had no impact on event-free survival (EFS) or overall survival (OS). EFS for patients receiving MTP was 69% compared with 61% for patients receiving chemotherapy alone (p=0.08). OS for patients receiving MTP was 78% compared with patients receiving chemotherapy alone (p=0.03). These authors concluded that MTP improved OS.

Comments: MTP is only available for investigative use, and there are no apparent plans to study this agent more extensively. This study, however, should stimulate such efforts.

Related News:

Onyvax-105 Shows Promising Results in Osteosarcoma (05/03/2005)

Surgery Required to Cure Osteosarcoma (11/19/2002)

Ethyol® May Prevent Granulocytopenia in Children Being Treated for Osteosarcoma (05/22/2002)

Reference:

¹ Meyers PA, Schwartz CL, Krallo MD, et al. Osteosarcoma: The addition of muramyl tripeptide to chemotherapy improves overall survival-A report from the Childrens Oncology Group. Journal of Clinical Oncology. 2008;26:633-638.