Effect of ibuprofen on monocyte activation by liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (CGP 19835A): can ibuprofen reduce fever and chills without compromising immune stimulation?

Mifamurtide for the treatment of nonmetastatic osteosarcoma

INTRODUCTION

The standard treatment for osteosarcoma requires both macroscopic surgical wide resection and postoperative multi-drug chemotherapy in neoadjuvant and adjuvant settings. However, the 5-year event-free survival has remained at a plateau of 60-70% of patients with nonmetastatic osteosarcoma for more than 30 years.

AREAS COVERED

Mifamurtide (liposomal muramyl tripeptide phosphatidylethanolamine; L-MTP-PE) is a new agent. L-MTP-PE is a nonspecific immunomodulator, which is a synthetic analog of a component of bacterial cell walls. L-MTP-PE activates macrophages and monocytes as a potent activator of immune response in addition to standard chemotherapy. It also improves the overall survival from 70 to 78% and results in a one-third reduction in the risk of death from osteosarcoma. This review summarizes the most recent findings about L-MTP-PE and its therapeutic application for nonmetastatic osteosarcoma.

EXPERT OPINION

Recently, L-MTP-PE has been approved in Europe for the treatment of nonmetastatic osteosarcoma with chemotherapy. L-MTP-PE in combination with traditional treatment is expected to go mainstream and to be beneficial for patients with osteosarcoma. Information about potential benefit regarding mifamurtide use in the neoadjuvant setting (i.e., before surgery) and/or usefulness of L-MTP-PE in metastatic in relapsed and metastatic osteosarcoma requires analysis of expanded access and/or future clinical trials of L-MTP-PE in high-burden and low-burden situations.

Mifamurtide: a review of its use in the treatment of osteosarcoma

Mifamurtide (liposomal muramyl tripeptide phosphatidyl ethanolamine; Mepact) is an immunomodulator with antitumor effects that appear to be mediated via activation of monocytes and macrophages. In the EU, mifamurtide is indicated in children, adolescents, and young adults for the treatment of high-grade, resectable, non-metastatic osteosarcoma after macroscopically complete surgical resection; it is administered by intravenous infusion in conjunction with postoperative multiagent chemotherapy. In the US, mifamurtide is currently an investigational agent that holds orphan drug status for the treatment of osteosarcoma. In a large, randomized, open-label, multicenter, phase III trial, the addition of adjuvant (postoperative) mifamurtide to three- or four-drug combination chemotherapy (doxorubicin, cisplatin, and high-dose methotrexate with, or without, ifosfamide) was associated with a statistically significant improvement in overall survival in patients with newly diagnosed, high-grade, non-metastatic, resectable osteosarcoma. The pattern of outcome was generally similar in a small cohort of patients with metastatic disease who were enrolled in this trial. Mifamurtide is generally well tolerated; adverse events attributed to administration of the drug include chills, fever, headache, nausea, and myalgias. Based on the available data, mifamurtide can be considered for inclusion in treatment protocols for localized osteosarcoma.

Muramyl tripeptide (mifamurtide) for the treatment of osteosarcoma

Osteosarcoma is an ultraorphan disease. There are approximately 1000 new patients diagnosed with osteosarcoma each year in the USA and Europe. Current treatment for osteosarcoma utilizes multiagent chemotherapy and surgical resection of all clinically detectable disease. Current treatments for osteosarcoma achieve 60-70% event-free survival (EFS) for patients with localized disease and approximately 20% EFS for patients who present with metastasis. These results have been stable for two decades. The addition of muramyl tripeptide (mifamurtide) to chemotherapy resulted in a trend towards improved EFS and a one-third reduction in the risk of death from osteosarcoma. Mifamurtide has been approved in Europe for the treatment of newly diagnosed osteosarcoma in combination with chemotherapy.

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.

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.

Biological activity of conjugates of muramyl dipeptides with batracylin derivatives

Antitumour activity of batracylin (BAT), muramyldipeptide (MDP) and four immunomodulatory conjugates of BAT with MDP were evaluated in the study. The activity was assessed using viability tests performed in the cultures of tumour cell lines of different tissue origin such as WEHI 164 (fibrosarcoma), K562 (leukaemia), and Ab (melanoma), populations of immune cells isolated from peripheral blood, and the tumour cells mixed with immune cells. An intensity of cell death caused by the analogues was measured using flow cytometry analysis as subG1 peak and the distinction between necrotic and apoptotic DNA cleavage during cell death was performed using DNA fragmentation assay. The compounds 11c, 11e and 11h managed to kill WEHI 164 cells in the presence of immune cells in apoptotic manner while BAT and conjugate 11a caused necrosis at the same time. Necrotic pattern of DNA cleavage was also noted in all cultures containing K562 and Ab cells. BAT and MDP caused necrosis in the cultures of pure immune cells, while the conjugates did not affect these cultures at all. Surprisingly, some analogues increased viability of K562 and Ab cells. Low toxicity and ability to induce apoptosis suggested usefulness of some analogues, mainly 11c, as antitumour drugs in limited range of tumours of certain tissue origin, such as WEHI 164.

Loss of shear stress induces leukocyte-mediated cytokine release and blood-brain barrier failure in dynamic in vitro blood-brain barrier model

Brain ischemia is associated with an acute release of pro-inflammatory cytokines, notably TNF-alpha and IL-6 and failure of the blood-brain barrier. Shear stress, hypoxia-hypoglycemia, and blood leukocytes play a significant role in blood-brain barrier failure during transient or permanent ischemia. However, these mechanisms have not been studied as independent variables for in vitro ischemia. The present study, using a dynamic in vitro blood-brain barrier model, showed that flow cessation/reperfusion under normoxia-normoglycemia or hypoxia-hypoglycemia without blood leukocytes in the luminal perfusate had a modest, transient effect on cytokine release and blood-brain barrier permeability. By contrast, exposure to normoxic-normoglycemic flow cessation/reperfusion with blood leukocytes in the luminal perfusate led to a significant increase in TNF-alpha and IL-6, accompanied by biphasic blood-brain barrier opening. Enhanced permeability was partially prevented with an anti-TNF-alpha antibody. In leukocyte-free cartridges, the same levels of IL-6 had no effect, while TNF-alpha caused a moderate increase in blood-brain barrier permeability, suggesting that blood leukocytes are the prerequisite for cytokine release and blood-brain barrier failure during reduction or cessation of flow. These cells induce release of TNF-alpha early after ischemia/reperfusion; TNF-alpha triggers release of IL-6, since blockade of TNF-alpha prevents IL-6 release, whereas blockade of IL-6 induces TNF-alpha release. Pre-treatment of blood leukocytes with the cyclooxygenase (COX) inhibitor, ibuprofen, inhibited cytokine release and completely preserved blood-brain barrier permeability during the reperfusion period. In conclusion, loss of flow (flow cessation/reperfusion) independent of hypoxia-hypoglycemia plays a significant role in blood-brain barrier failure by stimulating leukocyte-mediated inflammatory mechanisms.

Regional muramyl tripeptide phosphatidylethanolamine administration enhances hepatic immune function and tumor surveillance

BACKGROUND

Immune status of the liver may affect growth of liver metastases. We analyzed the ability of muramyl tripeptide phosphatidylethanolamine (MTP-PE), an immunomodulatory bacterial cell wall analog, to stimulate Kupffer cells (KCs) and protect against tumor growth, with or without an immunosuppressive partial hepatectomy (PH). Impact of MTP-PE's route of administration on KC function was assessed.

METHODS

Buffalo rats (n = 7 to 12/group) were treated with saline, 40 microg MTP-PE intraportally (portal) or intravenously (IV) and challenged with 5 x 10(5) hepatoma cells, and tumors counted on day 21. To assess MTP-PE's impact on KC stimulation in animals undergoing PH, a known stimulant of tumor cell growth, groups were treated with saline or MTP-PE and challenged with tumor and underwent 30% PH. KCs were harvested and analyzed for superoxide production. Statistical analysis was performed with Mann-Whitney U test or chi-square test.

RESULTS

MTP-PE-treated animals had fewer tumor nodules than control animals (19 vs 184, P <.005). MTP-PE-portal animals had fewer nodules than MTP-PE-IV (2 vs 36, P <.05). MTP-PE treatment before PH resulted in fewer tumor nodules compared with control animals (192 vs 276, P <. 05). MTP-PE administration increased macrophage superoxide production (20.6 +/- 2 vs 11.9 +/- 1.1 nmol/10(6) cells, P <.005).

CONCLUSIONS

MTP-PE improved KC function and decreased growth of microscopic tumor cells. MTP-PE's effects persist after an immunosuppressive hepatectomy. Portal administration was the most effective. MTP-PE administration may be useful as a neoadjuvant therapy for patients undergoing resection of liver malignancies.

Inhibition of cytokine production and adhesion molecule expression by ibuprofen is without effect on transendothelial migration of monocytes

The present study focusses on the effects of ibuprofen and its enantiomers on cytokine production by peripheral blood monocytes and endothelial cells as well as on the potential modulation of ADM-expression by human umbilical vein endothelial cells and the concomitant effects on monocyte transendothelial migration as measured by a cell migration assay system. This consists of an endothelial cell monolayer on a solid collagen substrate, i.e. an artificial vessel wall construct. We observed a significant inhibition by 100 microg/ml ibuprofen of VCAM-1 expression by endothelial cells while ELAM-1 and ICAM-1 expression was not influenced. However, we could not see any concomitant inhibitory effects on the spontaneous migration of monocytes after preincubating the endothelial cell monolayer with ibuprofen up to concentrations of 100 microg/ml and activating with suboptimal and optimal concentrations of TNF-alpha. Our monocyte transendothelial migration system reflects very sensitively endothelial cell-activation even by very low TNF-alpha concentrations. (S)- and (R)-ibuprofen were equal in their inhibitory/activating effects on cytokine production, with the exception of stronger IL-8 induction in endothelial cells by (R)-ibuprofen as compared to its chiral analogue.