Cytokine production and immune cell activation in melanoma patients treated with liposomal muramyl tripeptide (CGP 19835A lipid)

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.

Spontaneously occurring tumors of companion animals as models for human cancer

Spontaneous tumors in companion animals (dog and cat) offer a unique opportunity as models for human cancer biology and translational cancer therapeutics. The relatively high incidence of some cancers, similar biologic behavior, large body size, comparable responses to cytotoxic agents, and shorter overall lifespan are the factors that contribute to the advantages of the companion animal model. The tumor types that offer the best comparative interest include lymphoma/leukemia, osteosarcoma, STS, melanoma, and mammary tumors. With the increase in new therapeutic agents (traditional chemotherapy, gene therapy, biologic agents, etc.), the companion animal model can provide useful populations to test new agents where efficacy and toxicity can be examined.

Liposomal muramyl tripeptide (CGP 19835A lipid) therapy for resectable melanoma in patients who were at high risk for relapse: an update

Liposome-encapsulated muramyl tripeptide-phosphatidyl ethanolamine (L-MTP-PE) was used in a pilot study for resectable melanoma patients who were at high risk for relapse. We entered 18 evaluable patients. The patient group included: (a) patients with stage III disease and clinically measurable regional metastases at presentation as confirmed by needle biopsy and (b) patients with stage IV disease presenting with measurable and resectable distant metastases confirmed by needle biopsy and limited to lungs, lymph nodes and subcutaneous tissues. L-MTP-PE was given for 4 weeks prior to surgical resection and for an additional 20 weeks postoperatively. Disease-free intervals were then determined based on the date of surgery. A preliminary report published in 1993 indicated an average disease-free interval of 18 months (range 8-33 months). This article presents an updated report on the long-term, disease-free survival status of these patients and shows that of the 18 evaluable patients, 4 remain free of disease for more than 5 years after surgical resection and therapy. The period of survival for these patients ranged from 69 months to more than 91 months (average 80.5 months). Although this was only a pilot study, we believe that the duration of survival indicates that L-MTP-PE may produce significant biologic activity in patients with melanoma, resulting in long-term benefits in terms of tumor eradication.

Controlled delivery of antigens and adjuvants in vaccine development

Advances in the understanding of the pathogenesis of infectious diseases and cancer immunology have inspired many new approaches to vaccine development. Many subunit antigens and peptides that are effective for vaccination have been discovered. These subunit antigens in tum stimulate synthesis of effective adjuvants to enhance their immunogenicity. Controlled-release technology offers the potential of further improving the efficacy of conventional vaccine formulations by optimizing the temporal and spatial presentation of the-antigens and adjuvants to the immune system. The combination of sustained release and depot effect may also reduce the amount of antigens or adjuvants needed and eliminate the booster shots that are necessary for the success of many vaccinations. This review examines the contribution controlled release technology can make in various areas of vaccination, with an emphasis on tumor vaccines.

Maintenance of intestinal epithelium structural integrity and mucosal leukocytes during chemotherapy by oral administration of muramyl tripeptide phosphatidylethanolamine

The systemic administration of doxorubicin (DXR) decreases the number of epithelial cells and leukocytes in the small intestine of mice. Oral administration of muramyl tripeptide phosphatidylethanolamine (MTP-PE) prevented both disruption of intestinal architecture, and a decrease in the number of macrophages, and it induced the expression of IL-6, G-CSF, GM-CSF, and TNF-alpha in the intestinal tissue. The data suggest that the oral administration of MTP-PE can prevent chemotherapy-induced toxicity to the intestinal mucosa and hence infections due to translocation of aerobic bacteria from the intestine to the blood.

Impairment of lymphocyte locomotion in the tumor microenvironment and the effect of systemic immunotherapy with liposome-encapsulated muramyl-tripeptide-phosphatidylethanolamine

The ability of the lymphocytes to move through the interstitium is obligatory to the immune response. We previously showed that tumor-infiltrating lymphocytes (TIL) from human melanoma and renal cell carcinoma demonstrate a dramatic decrease in their spontaneous locomotion through three-dimensional collagen gel when compared with peripheral blood lymphocytes (PBL) and lymph node lymphocytes. To determine if this decrease is caused by contact with tumor cells, or mediated through certain diffusible factors, we examined the effects of autologous tumor cells on the locomotion of PBL in a model system where tumor cells were separated from lymphocytes by a 3-mm layer of gelled collagen. After 21-22 h incubation in chamber slides, locomotion distances were assessed in the presence and absence of tumor and normal cells. In the presence of tumor cells, PBL from 14 of 18 patients displayed substantial (466.5 +/- 2.7 microns compared to control 568.9 +/- 10.9 microns, P < 0.001) loss of motility. Inhibition was more prominent in melanoma patients than in renal cell carcinoma patients. Thus the impaired locomotion previously observed in TIL was at least partially due to the presence of tumor. The locomotion of TIL was restored in four of five melanoma patients treated with liposome-encapsulated muramyl-tripeptide-phosphatidylethanolamine (L-MTP-PE). Furthermore, in six of seven examined L-MTP-PE-treated patients, an increase in intrinsic PBL locomotion during the first month of the therapy was observed. These results suggest that the environment of the tumor is not conducive to locomotion of advancing lymphocytes and the therapeutic intervention may ameliorate the loss of lymphocytic infiltration.