Therapy of cancer metastasis by systemic activation of macrophages: from the bench to the clinic.
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Animals↗
Biomedical subjects
E S Kleinerman
Publications and source records attributed to E S Kleinerman.
Liposome-encapsulated MTP-PE: a novel biologic agent for cancer therapy.
Liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE), a new biologic response modifier, was designed to target the immunomodulator to monocytes and macrophages. Human monocytes/macrophages phagocytize L-MTP-PE, with subsequent upregulation of interleukin (IL)-1 alpha, IL-1 beta, IL-6, IL-8, tumor necrosis factor (TNF)-alpha, and monocyte chemotactic and activating factor genes and with the production and secretion of these cytokines in vitro. L-MTP-PE-activated macrophages kill tumor but not normal cells in vitro. Following i.v. infusion of L-MTP-PE into cancer patients, its uptake was demonstrated in liver, spleen, lung, and in and around metastases to lung. We also investigated whether L-MTP-PE therapy administered in a neoadjuvant setting could improve the disease-free interval in relapsed osteosarcoma patients with lung metastasis. Patients received either a 12- or 24-week course of L-MTP-PE after surgical removal of all metastases. Following L-MTP-PE infusion, induction of circulating TNF-alpha, IL-6, neopterin, and C-reactive protein was demonstrated. Disease-free intervals were calculated from the day of surgery to the day of relapse in each group and were compared with the disease-free interval for a historical control group. Those patients receiving 24 weeks of L-MTP-PE showed a significant (p < 0.03) prolongation in time to relapse. These data indicate that L-MTP-PE is an active agent against osteosarcoma and warrants further investigation in an adjuvant setting.
Acetylmuramyl-Alanyl-Isoglutamine↗
Unique histological changes in lung metastases of osteosarcoma patients following therapy with liposomal muramyl tripeptide (CGP 19835A lipid).
We have recently begun a phase II trial in patients with osteosarcoma who developed pulmonary metastases during adjuvant chemotherapy or who presented with pulmonary metastases that persisted despite chemotherapy. Eligible patients were rendered free of visible disease by surgery. Liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (MTP-PE, CGP 19835A lipid) (2 mg/m2) was infused twice weekly for 3 months. In five patients, a single tumor nodule recurred within 6 weeks after completion of therapy. These lesions were resected and submitted for pathological examination. Tissue specimens obtained after therapy were compared to those obtained before therapy. All the patients showed a histological change in the characteristics of the pulmonary tumors. In three patients, peripheral fibrosis surrounded the tumor and inflammatory cell infiltration and neovascularization were present. This is in contrast to central necrosis, with viable peripheral tumor cells and no inflammatory response observed in lesions resected following chemotherapy. In a fourth case, evidence of early fibrotic changes was found. This and the fifth case showed a change in malignant characteristics, from high grade before liposomal therapy to low grade after therapy. The present study provides evidence for a biological effect of liposomal MTP-PE.
Acetylmuramyl-Alanyl-Isoglutamine↗
Phase II study of liposomal muramyl tripeptide in osteosarcoma: the cytokine cascade and monocyte activation following administration.
PURPOSE: A phase II trial that uses liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) in patients with relapsed osteosarcoma is underway. To determine if in vivo cytokine induction plays a role in the mechanism of action of L-MTP-PE, we investigated the circulating cytokine levels of 16 patients who were undergoing therapy. PATIENTS AND METHODS: Patients had histologically proven osteosarcoma and pulmonary metastases that developed either during adjuvant chemotherapy or that were present at diagnosis and persisted despite chemotherapy. Patients were rendered disease-free by surgery. The major goal of the study was to improve the disease-free interval in this high-risk group. L-MTP-PE 2 mg/m2 was infused during a 1-hour period twice a week for 12 weeks, then once a week for 12 weeks. Serial blood samples were collected after L-MTP-PE administration and were assayed for cytokine levels (tumor necrosis factor-alpha [TNF alpha] interleukin-1 alpha [IL-1 alpha], IL-1 beta, IL-6, interferon-gamma [IFN-gamma], neopterin, C-reactive protein). RESULTS: After the infusion of L-MTP-PE, there was rapid induction of circulating TNF alpha and IL-6. TNF alpha levels peaked 1 to 2 hours after infusion in 10 of 16 patients, whereas peak IL-6 levels were detected at 2 to 3 hours in all patients. Induction of circulating TNF alpha and IL-6 was evident only after the first dose of L-MTP-PE. Neither IL-1 alpha nor IL-1 beta was detected in the plasma. Neopterin levels increased at 24 hours postinfusion, which indicated macrophage activation, and were not related to the induction of circulating IFN-gamma. C-reactive protein was elevated in all patients at 24 hours and decreased by 72 hours. Unlike circulating TNF alpha and IL-6, elevations in C-reactive protein and neopterin could be detected throughout the treatment course. CONCLUSION: It is concluded that L-MTP-PE has specific biologic effects in patients with osteosarcoma that may be important to the drug's immunostimulatory capacity and its effectiveness as an antitumor agent.
Acetylmuramyl-Alanyl-Isoglutamine↗
Sequential therapy with chemotherapeutic drugs and liposome-encapsulated muramyl tripeptide: determination of potential interactions between these agents.
Three syngeneic murine tumor models were used to determine potential interactions between chemotherapeutic drugs and the synthetic liposome-encapsulated macrophage activator, muramyl tripeptide phosphatidylethanolamine (MLV-19835). Experiments were designed to maximize any additive toxicity of the simultaneous administration of MLV-19835 on the known myelosuppressive effects of doxorubicin, ifosfamide, and cisplatin. Treatment with these drugs resulted in diminished blood leukocyte counts, altered leukocyte differentials, and decreased hematocrits, but the systemic administration of MLV-19835 produced no additional deleterious effects. Myelosuppression normally observed at 2 weeks following treatment of mice with doxorubicin was prevented by combination treatment with MLV-19835. In addition, there was no interference of the antitumor activity of ifosfamide or doxorubicin against subcutaneous, kidney, and spleen tumors. These studies and the recent demonstration of the biological activity of MLV-19835 in phase II trials of osteosarcoma recommend clinical testing of these combined modalities.
Acetylmuramyl-Alanyl-Isoglutamine↗
Influence of chemotherapy administration on monocyte activation by liposomal muramyl tripeptide phosphatidylethanolamine in children with osteosarcoma.
The purpose of these studies was to determine whether chemotherapy interfered with the ability of peripheral blood monocytes from patients with osteosarcoma to respond to the liposome-encapsulated activating agent muramyl tripeptide phosphatidylethanolamine (L-MTP-PE). This was done in preparation of designing an adjuvant therapy protocol that includes L-MTP-PE combined with chemotherapy postoperatively for the treatment of primary osteosarcoma. The majority of patients who fail current adjuvant chemotherapy do so while on chemotherapy. Therefore, we believe it is important to combine L-MTP-PE with chemotherapy early in the treatment course rather than waiting until all chemotherapy cycles are completed. The tumoricidal properties of monocytes from patients with osteosarcoma could be activated by L-MTP-PE to levels equal to or greater than those expressed by normal control monocytes. No intrinsic monocyte defect could be demonstrated. Single-agent chemotherapy consisting of cisplatin (CPD), high-dose methotrexate (MTX), Cytoxan (CTX, cyclophosphamide; Bristol-Myers Co, Evansville, IN), or Adriamycin (ADR, doxorubicin; Adria Laboratories, Columbus, OH) did not interfere with this activation process. There was even a suggestion of enhanced activation potential following the administration of ADR. However, when both ADR and CTX were administered together on the same day, profound suppression in monocyte activation was observed. This suppressed function returned to normal by 3 weeks postcombination therapy. We therefore conclude that L-MTP-PE can be combined with ADR, CPD, MTX, or CTX as single agents but recommend that ADR plus L-MTP-PE is the most effective combination. By contrast, we discourage the use of L-MTP-PE when ADR and CTX are given together.
Acetylmuramyl-Alanyl-Isoglutamine↗
Muramyl tripeptide phosphatidylethanolamine encapsulated in liposomes stimulates monocyte production of tumor necrosis factor and interleukin-1 in vitro.
Muramyl tripeptide phosphatidylethanolamine (MTP-PE), a synthetic lipophilic analogue of muramyl dipeptide (MDP), can be incorporated into the lipid membrane of liposomes. Liposomes containing MTP-PE (L-MTP-PE) stimulated monocytes to selectively kill tumors, but not normal cells in vitro. Furthermore, the activation of monocyte tumoricidal function was demonstrated following the i.v. infusion of L-MTP-PE in a phase I trial with cancer patients. The purpose of this study was to determine the mechanism by which L-MTP-PE activates monocytes. Monocyte tumoricidal function is linked to both interleukin-1 (IL-1) and tumor necrosis factor (TNF). Therefore, normal human monocytes were incubated for various times with L-MTP-PE, empty liposomes, or medium in the presence or absence of gamma interferon (IFN-gamma). The supernatants were removed and assayed for TNF and IL-1 using the L929 and D10.G4.1 assays, respectively. TNF was detected after a 4 hr incubation with L-MTP-PE but not with empty liposomes or medium. TNF secretion peaked at 8 hr and was sustained for up to 72 hr. A 4-fold increase in TNF mRNA levels was demonstrated after 8 hr. An increased level of IL-1 beta mRNA was detected after a 4 hr incubation, but only low level IL-1 secretion was detected in monocytes incubated with L-MTP-PE. Adherent monocytes were frozen and thawed to release intracellular IL-1. Intracellular IL-1 was significantly increased in monocytes incubated with L-MTP-PE. Intracellular IL-1 levels peaked by 8 hr and decreased by 72 hr. Activators were then assayed in the presence or absence of IFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)
Acetylmuramyl-Alanyl-Isoglutamine↗
Antitumor activity of TNF-alpha, IL-1, and IFN-gamma against three human osteosarcoma cell lines.
Osteosarcoma is the most common primary malignant bone tumor. The peak incidence is in adolescence and the prognosis is very poor. Even after amputation and chemotherapy, many patients who suffer from osteosarcoma die of lung metastases within 2 years. This report documents a study of the in vitro antitumor activity of cytokines against three human osteosarcoma cell lines. The cell lines MG-63, SAOS-2, and TE-85 were incubated with TNF-alpha, IL-1, or IFN-gamma alone or in combination. TNF-alpha, IL-1, and IFN-gamma had antiproliferative activity against all three cell lines. TNF-alpha and IFN-gamma were the most effective against SAOS-2; MG-63 cells were the most sensitive to IL-1, and TE-85 cells were resistant to TNF-alpha and IL-1 but sensitive to IFN-gamma. The synergistic antitumor effect of TNF-alpha plus IFN-gamma, IL-1 alpha, or IL-1 beta or of IFN-gamma plus IL-1 alpha or IL-1 beta was higher than that obtained when the cytokines were employed alone.
Cell Division↗
Inhibition of protein kinase C by a peptide conjugate homologous to a domain of the retroviral protein p15E.
Retroviral infection is associated with immunosuppression, which has been shown to be due, in part, to the action of the envelope protein p15E. We studied a synthetic peptide (CKS-17) homologous to a highly conserved domain of the retroviral envelope protein p15E, which, when conjugated to BSA (CKS-17-BSA), can inhibit IL-1- and phorbol ester-mediated responses in cultured murine thymoma cells, and Ca2(+)- and phosphatidylserine-dependent protein kinase C (PKC) activity of cell homogenates. We characterized the mechanism of inhibition of PKC by the peptide. Using PKC purified from rat brain we found that CKS-17-BSA inhibited PKC-catalyzed Ca2(+)- and phosphatidylserine-dependent histone phosphorylation with an estimated ID50 of 4 microM. CKS-17-BSA did not inhibit the catalytic subunit of cAMP-dependent protein kinase. CKS-17-BSA also inhibited the Ca2(+)- and PS-independent activity of a catalytic fragment of PKC that was generated by limited trypsin treatment. However, CKS-17-BSA did not act as a competitive inhibitor of PKC with respect to ATP or phosphoacceptor substrate, despite the similarity between the CKS-17 sequence and substrates and pseudosubstrates of PKC. We conclude that this peptide homologue of a retroviral envelope protein has a novel mechanism of inhibition of PKC.
Amino Acid Sequence↗
Effect of recombinant human interleukin 4 on human monocyte activity.
Recombinant human interleukin 4 (rhuIL-4), a lymphokine that reportedly stimulates tumoricidal activity in mouse macrophages, is currently undergoing clinical studies to determine its efficacy in the treatment of cancer. IL-4 is known to participate with other cytokines to regulate growth and differentiation of various hematopoietic cells as well as modulate the immune response. Little is known about the effect of rhuIL-4 on human monocyte tumoricidal activity. The purpose of these studies was to examine the effect of rhuIL-4 on human peripheral blood monocytes. Peripheral blood monocytes isolated from normal donors failed to demonstrate tumoricidal activity or interleukin 1 secretion after treatment with rhuIL-4 in vitro. Furthermore, monocyte-mediated cytotoxicity induced by recombinant human gamma-interferon plus muramyl dipeptide was suppressed in a dose-dependent manner by rhuIL-4. This reduction in cytotoxicity corresponded to a reduction in IL-1 production and secretion. Further investigation of rhuIL-4 and its role in the cytokine network is necessary for the development of effective immunotherapy in cancer patients.
Acetylmuramyl-Alanyl-Isoglutamine↗
Innate resistance to herpes simplex virus infection. Human lymphocyte and monocyte inhibition of viral replication.
Peripheral blood monocytes and lymphocytes isolated from most humans are resistant to HSV infection in vitro. Viral replication is inhibited very early in the cycle, prior to the onset of alpha-protein synthesis; no viral protein or DNA synthesis is detectable even up to 1 week later. The enhanced expression of two 62-kDa and 57-kDa cellular proteins, however, is induced in the lymphocyte population within 3 to 5 h after infection. A 30-kDa protein is induced in the monocyte population immediately after infection. The induced expression of 62-kDa and 57-kDa lymphocyte proteins appears to be virus-mediated because: a) HSV and pseudorabies virus (although not vaccinia virus) induce the expression of 62-kDa and 57-kDa proteins, b) heat shock or exposure of lymphocytes to uninfected cell extracts does not induce expression of either protein, c) 62-kDa protein is not induced in lymphocytes stimulated with a mitogenic concentration of PHA. UV-inactivated HSV induces expression of 62-kDa and 57-kDa proteins in a manner similar to that observed with untreated virus. In contrast, expression of 30-kDa monocyte protein is induced nonspecifically by either uninfected cell extracts or cell extracts containing virus. Sixty-two-kilodalton and 57-kDa protein induction appears to be a marker for human lymphocytes that express profound intracellular resistance to infection with HSV. Induced expression of these proteins occurs only in lymphocytes that inhibit viral replication very early in the growth cycle, prior to the onset of alpha-protein synthesis. Expression of 62-kDa and 57-kDa proteins is not induced in lymphocytes that are permissive or partially permissive to infection with HSV.
Cells, Cultured↗
Macrophages and cancer.
The uncontrolled growth of metastases resistant to conventional therapeutic modalities is a major cause of death from cancer. Data from our laboratory and others indicate that metastases arise from the nonrandom spread of specialized malignant cells that preexist within a primary neoplasm. These metastases can be clonal in their origin, and different metastases can originate from different progenitor cells. In addition, metastatic cells can exhibit an increased rate of spontaneous mutation compared with benign nonmetastatic cells. These data provide an explanation for the clinical observation that multiple metastases can exhibit different sensitivities to the same therapeutic modalities. These findings suggest that the successful therapy of disseminated metastases will have to circumvent the problems of neoplastic heterogeneity and the development of resistance. Appropriately activated macrophages can fulfill these demanding criteria. Macrophages can be activated to become tumoricidal by interaction with phospholipid vesicles (liposomes) containing immunomodulators. Tumoricidal macrophages can recognize and destroy neoplastic cells in vitro and in vivo, leaving nonneoplastic cells uninjured. Although the exact mechanism(s) by which macrophages discriminate between tumorigenic and normal cells is unknown, it is independent of tumor cell characteristics such as immunogenicity, metastatic potential, and sensitivity to cytotoxic drugs. Moreover, macrophage destruction of tumor cells apparently is not associated with the development of tumor cell resistance. Macrophages are found in association with malignant tumors in a definable pattern, suggesting that the most direct way to achieve macrophage-mediated tumor regression is in situ macrophage activation. Intravenously administered liposomes are cleared from the circulation by phagocytic cells, including macrophages, so when liposomes containing immunomodulators are endocytosed, cytotoxic macrophages are generated in situ. The administration of such liposomes in certain protocols has been shown to bring about eradication of cancer metastases. Macrophage destruction of metastases in vivo is significant, provided that the total tumor burden at the start of treatment is minimal. For this reason, we have been investigating various methods to achieve maximal cytoreduction in metastases by modalities such as chemotherapy or radiotherapy prior to macrophage-directed therapy. It is important to note that even the destruction of 99.9% of cells in a metastasis measuring 1 cm2 would leave 10(6) cells to proliferate and kill the host. The ability of tumoricidal macrophages to distinguish neoplastic from bystander nonneoplastic cells presents an attractive possibility for treatment of the few tumor cells which escape destruction by conventional treatments. Macrophage-directed therapy has been studied in several human protocols, yielding important biological information about the use of liposome-encapsulated macrophage activators in cancer patients.(ABSTRACT TRUNCATED AT 400 WORDS)
Adjuvants, Immunologic↗
A new familial immunodeficiency disorder characterized by severe neutropenia, a defective marrow release mechanism, and hypogammaglobulinemia.
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Adult↗
Differential release of TNF-alpha, IL 1, and PGE2 by human blood monocytes subsequent to interaction with different bacterial derived agents.
The purpose of these studies was to determine whether the tumoricidal phenotype of human blood monocytes would be affected by different activation signals. Human monocytes obtained by elutriation of buffy coats were cultured in vitro in medium containing LPS, muramyltripeptide phosphatidylethanolamine (MTP-PE), or a lipopeptide analogue of gram-negative bacteria cell wall. These immunomodulators were added to monocytes in the presence or absence of IFN-gamma. Incubation with LPS, lipopeptide, and MTP-PE rendered the monocyte cytotoxic against allogeneic melanoma cells. Monocytes treated with LPS and lipopeptide (in the absence of IFN-gamma) secreted IL 1, TNF, and PGE2. In contrast, monocytes incubated with MTP-PE (in the absence of IFN-gamma) secreted only TNF. When the monocytes were coincubated with IFN-gamma (human but not mouse) and the immunomodulators, IL 1, TNF, and PGE2 were secreted at all test groups. These data show that some immunomodulators can regulate the release of TNF independently of IL 1 and that not all "activated tumoricidal macrophages" share identical phenotypes.
Acetylmuramyl-Alanyl-Isoglutamine↗
Liposomal MTP-PE for the adjuvant therapy of osteosarcoma.
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Acetylmuramyl-Alanyl-Isoglutamine↗
Activation of tumoricidal properties in monocytes from cancer patients following intravenous administration of liposomes containing muramyl tripeptide phosphatidylethanolamine.
This study examined the antitumor properties of blood monocytes isolated from patients undergoing a phase I trial with liposomes containing muramyl tripeptide phosphatidylethanolamine (L-MTP-PE). Peripheral blood monocytes were isolated from 28 patients receiving twice weekly i.v. injections of escalating doses of L-MTP-PE. Monocytes were harvested before therapy and at various times during the 9-week treatment period. Activation of monocyte-mediated tumorilytic activity was found in 24 of the 28 patients at some time during treatment. Whereas the maximum tolerated dose of L-MTP-PE was 4-6 mg/m2, the optimal biological dose in terms of macrophage activation was 0.5-2.0 mg/m2. The spontaneous secretion of interleukin 1 from monocytes isolated pre- and postinfusion was monitored in two patients. In both patients interleukin 1 secretion correlated with the cytotoxic activity of the monocytes. We conclude that the systemic administration of L-MTP-PE can render the blood monocytes of cancer patients tumor cytotoxic. Since L-MTP-PE is an immunomodulator devoid of direct antiproliferative effects on tumor cells, the data suggest that future clinical trials be conducted using the optimal biological dose rather than the maximum tolerated dose.
Acetylmuramyl-Alanyl-Isoglutamine↗
Synthetic peptide corresponding to a conserved domain of the retroviral protein p15E blocks IL-1-mediated signal transduction.
We studied the mode of action of the synthetic peptide CKS-17, which is a heptadecapeptide homologous to a highly conserved region of the immunosuppressive retroviral envelope protein p15E, as well as to envelope proteins of the human T cell leukemia virus I and II. Previous studies have established that CKS-17 conjugated to BSA (CKS-17-BSA) inhibited IL-1-mediated tumor toxicity in melanoma cells and proliferation in murine Th clones. We examined the effects of CKS-17-BSA on IL-1 action. CKS-17-BSA did not bind to IL-1, nor did it affect the number of IL-1 receptors, their binding affinity, or their ability to internalize IL-1. However, CKS-17-BSA inhibited production of IL-2 by murine thymoma cells treated with IL-1 or with 12-O-tetradecanoyl phorbol-13 acetate. The potent protein kinase C inhibitor, H7, also inhibited IL-1-mediated responses, while HA1004, a weak inhibitor of protein kinase C, did not. Protein kinase C activity in the cytosolic fraction prepared from thymoma cells was found to be inhibited by CKS-17-BSA in a dose-dependent manner. All of these findings are consistent with the idea that CKS-17-BSA inhibits IL-1-mediated responses by interfering with signal transduction through a protein kinase C pathway.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Lithium chloride stimulates human monocytes to secrete tumor necrosis factor/cachectin.
The purpose of this study was to examine the effect of lithium chloride (LiCl) on human monocytes. Patients undergoing lithium therapy have elevated white blood cell counts. Since both tumor necrosis factor alpha (TNF alpha) and interleukin 1 (IL-1), which are secreted by monocytes, can stimulate endothelial cells to produce granulocyte-macrophage colony-stimulating factor (GM-CSF), we determined whether lithium-stimulated monocytes produced TNF alpha and/or IL-1. Normal human monocytes were incubated for 24 h with medium (negative control), lipopolysaccharide (positive control), or LiCl (0.05-50 mM). The supernatants were removed and assayed for IL-1 and TNF alpha secretion using the D10.G4.01 and L929 assays, respectively. Lithium did not stimulate IL-1 secretion but did stimulate TNF alpha secretion (5-10 U/ml of TNF alpha per 2 x 10(5) monocytes). The increased secretion of TNF alpha was associated with a fourfold increase in TNF alpha mRNA. TNF alpha activity in the supernatants was neutralized by a monoclonal antibody against human TNF alpha but not by antibody against human albumin. Other alkali metals such as rubidium and cesium did not stimulate monocytes to secrete TNF alpha. These data indicate that one mechanism by which Li may cause granulocytosis is through a transcriptional enhancement of TNF production and subsequent secretion by monocytes.
Chlorides↗