Active immunotherapy of human solid tumor with autologous cells treated with cholesteryl hemisuccinate. A Phase I study

Cholesteryl hemisuccinate as a membrane stabilizer in dipalmitoylphosphatidylcholine liposomes containing saikosaponin-d

In the present study, cholesteryl hemisuccinate (CHEMS) was evaluated for use as a membrane stabilizer in dipalmitoylphosphatidylcholine (DPPC) liposomes. Differential scanning calorimetry (DSC) and a calcein release study showed that CHEMS was more effective than cholesterol (CHOL) in increasing DPPC membrane stability. The findings of Fourier transform infrared spectroscopy (FT-IR) also suggested that CHEMS interacts with DPPC via both hydrogen bonding and electrostatic interaction. More importantly, CHEMS did not interact with saikosaponin-d (SSD), a triterpene saponin from Bupleurum species, unlike CHOL. SSD-containing liposomes with DPPC, CHEMS and DSPE-PEG could greatly decrease the hemolytic activity of SSD. This study demonstrated that CHEMS has more stabilization ability than CHOL since CHEMS may exhibit both hydrogen bond interaction and electrostatic interaction with DPPC membrane while CHOL only has hydrogen bond interaction, resulting in stable and low-hemolytic SSD-liposomes.

Evaluation of tumor-associated antigen (2H6 antigen) in detecting early stages of gastric cancer

A sandwich enzymed-linked immunosorbent assay (ELISA) was developed by using monoclonal antibody 2H6 (2H6 MoAb). MoAb 2H6 could be used to detect the 2H6 antigen in the sera of several cancers, showing positive rates of 65.4%, 66.7%, 47.4%, 80.0%, 45.2% and 16.7% in gastric cancer, hepatocellular carcinoma, cancers of the colon, esophagus, breast and pancreas, respectively. On the other hand, the positive rates in benign diseases or healthy donors were 3.4%, 3.4%, 4.2%, 8.3%, 6.9%, and 1.2% in myasthenia gravis, polymyositis, gastritis, gastric ulcer, other benign diseases and normal healthy donors, respectively. Fifty-two patients with gastric cancer were investigated in detail. The positive rates of serum 2H6 antigen, CEA, AFP, CA19-9 and CA125 in patients with gastric cancer were 65.4%, 9.6%, 2.3%, 25.0% and 8.1%, respectively. Among these tumor markers, serum 2H6 antigen levels alone were significantly elevated in patients with early stage (I and II) gastric cancer. Furthermore, combining the measurement for serum 2H6 with CA19-9 increased the percentage of gastric cancer slightly. No correlation between 2H6 antigen and these other tumor markers was observed. The serum levels of 2H6 antigen were monitored post-surgically in 11 patients for 12 weeks and they were found to diminish gradually. The findings suggest that the measurement of serum 2H6 antigen may be a useful marker for an early stage of gastric cancer.

Increased projection of MHC and tumor antigens in murine B16-BL6 melanoma induced by hydrostatic pressure and chemical crosslinking

The B16-BL6 melanoma, like most spontaneously arising tumors, is poorly immunogenic and expresses low levels of major histocompatibility complex (MHC) antigens. Treatment of cells of this tumor in vitro by hydrostatic pressure in the presence of adenosine 2',3'-dialdehyde (oxAdo), a membrane-impermeant crosslinker, caused elevated projection of MHC and a specific tumor antigen as demonstrated by flow-cytometric analysis. Maximum projection of both the MHC and the tumor antigens could be reached by application of 1200 atm for 15 min in the presence of 20 mM oxAdo. It is not yet clear whether this passive increase in availability of antigens on the cell surface originated from a dormant pool of antigens in the plasma membrane or from pressure-induced fusion of antigen-rich intracellular organelles (e.g. the endoplasmic reticulum). The immunogenic properties of the antigen-enriched B16-BL6 cells are described in the following paper.

Melanoma tumor vaccine: five-year follow-up

For many years, various melanoma vaccines have been employed. This is a unique melanoma vaccine in that it is a subcellular tumor homogenate and no adjuvants have been added. This vaccine has been given to 129 stage I and 61 stage II melanoma patients. All were followed at least 5 years and had 87.5% and 63.9% 5-year survival rates, respectively. Sixty-four stage I males and 65 stage I females had 84% and 90% 5-year survival rates, respectively. We saw no difference between those with or without lymph node dissection. Thirty-six stage II males and 25 stage II females had 66.7% and 60% 5-year survival rates, respectively. Of stage II patients, 23 had only one positive node, 22 had two to four positive nodes, and 9 had five or more positive nodes with 69%, 63%, and 55% 5-year survival rates, respectively. Large published series were used as historical controls [6,27,28], and significant differences were noted when compared to our stage II patients (P = 0.001)--those with two to four positive nodes (P = 0.03), and those with five or more positive nodes (P = 0.04). We conclude that there is a significant increase in survival for these stage II patients, at high risk of recurrence, receiving a tumor homogenate vaccine. This vaccine warrants further analysis, development, and use in a phase III randomized clinical trial.

Immunotherapy for malignant melanoma: a review and update

Several different approaches to the application of specific active immunotherapy for the adjuvant therapy of melanoma have developed independently. Specific active immunotherapy refers to autologous or allogenic inoculation or transplantation of tumor cells or cell products into patients with cancer. Several different types of tumor vaccines have been studied and have been combined with different immunotherapeutic modalities. This report will include a review of several of those different techniques and will also review the observed 5-year survival rates for a melanoma tumor homogenate (concentrated) vaccine, developed by L.J. Humphrey and colleagues.

Potentiation of delayed-type hypersensitivity response to syngeneic tumors in mice prevaccinated with cells modified by hydrostatic pressure and crosslinking

Delayed-type hypersensitivity (DTH) to the chemically induced EL4 and virally induced ARadLV 136 leukemia cells was determined by the radioactive ear test. Prior to the DTH test, mice were prevaccinated with cells treated either with hydrostatic pressure or with the membrane-impermeant crosslinker adenosine dialdehyde or with a combination of these. For both tumor cells, DTH against unmodified cells was markedly potentiated by prevaccination with cells treated with hydrostatic pressure combined with adenosine dialdehyde. In vitro cytotoxicity data indicated that maximal lysis of target cells is induced by vaccination with adenosine-dialdehyde-treated cells, as well as by pressure in combination with adenosine dialdehyde treatment. In addition, increased [3H]thymidine uptake was observed in effector T cells induced by prevaccination with tumor cells modified by adenosine dialdehyde or pressure or both. This novel and innocuous potentiation of an antitumor immune response may have a practical utility in the treatment of human cancer.

Susceptibility of RDM4 lymphoma cells to LAK-mediated lysis is decreased in tumor bearers fed fish oil high fat regimen

RDM4 lymphoma cells were grown intraperitoneally in genetically compatible AKR mice fed either regular mouse chow, or diet supplemented with either saturated fat (hydrogenated beef tallow = HBT) or unsaturated fat (fish oil = FO). It was observed that the lymphoma cells number was significantly greater in FO-fed hosts and lower in HBT-fed hosts, than in the mice fed regular chow. The tumor bearers diet did not dramatically influence the rate of DNA synthesis of RDM4 cells, as measured by [3H]thymidine uptake in culture, a few hours after harvesting from the peritoneal cavity. It was repeatedly found that FO feeding of the tumor bearers elicited an increased resistance of RDM4 cells to lysis by LAK effectors, as appraised in vitro by 51Cr release test and in vivo by the "Winn assay". Different FO percentage of the diet (16%, 8%, 4%) resulted in comparable reduction of susceptibility of RDM4 cells to lysis by LAK effectors. Lipid analysis showed that RDM4 cells grown in mice fed FO diet or HBT diet differed markedly in their fatty acid composition and that their resistance to lysis by LAK cells correlated with the quantity of oxidizable fatty acids especially of the n-6 type.

Effect of dietary lipids on plasma lipoproteins and fluidity of lymphoid cell membranes in normal and leukemic mice

Mice of the GR/A strain were fed four different isocaloric semipurified diets, enriched in either (1) saturated fatty acids (palm oil), or (2) polyunsaturated fatty acids (corn oil), or (3) palm oil plus cholesterol, or (4) a fat-poor diet containing only a minimal amount of essential fatty acids. We have studied the effects of these dietary lipids on the density profile and composition of the plasma lipoproteins and on the lipid composition and fluidity of (purified) lymphoid cell membranes in healthy mice and in mice bearing a transplanted lymphoid leukemia (GRSL). Tumor development in these mice occurred in the spleen and in ascites. While the fatty acid composition of the VLDL-triacylglycerols still strongly resembled the dietary lipids, the effects of the diets decreased in the order VLDL-triacylglycerols greater than HDL-phospholipids greater than plasma membrane phospholipids. Diet-induced differences in the latter fraction were virtually confined to the content of oleic acid and linoleic acid, and they were too small to affect the membrane fluidity, as measured by fluorescence polarization using the probe 1,6-diphenyl-1,3,5-hexatriene. Healthy mice were almost irresponsive to dietary cholesterol, but in the tumor bearers, where lipoprotein metabolism has been shown to be disturbed, the cholesterol diet caused a substantial increase in the low- and very-low density regions of both blood and ascites plasma lipoproteins. The cholesterol-rich diet also increased the cholesterol/phospholipid molar ratio and lipid structural order (decreased fluidity) in GRSL ascites cell membranes, but not in the splenic GRSL cell membranes. We conclude that the composition of plasma lipoproteins and cell membrane lipids in GR/A mice is subject to exquisite homeostatic control. However, in these low-responders to dietary lipids the development of an ascites tumor may lead to increased responsiveness to dietary cholesterol. The elevated level of membrane cholesterol thus obtained in GRSL ascites cells did not affect the expression of various cell surface antigens or tumor cell growth.

Expression of HLA-DR antigens on tumour cells does not contribute to skin reactivity to autologous cholesteryl hemisuccinate (CHS)-treated tumour cells in patients with metastatic melanoma

Skin tests with autologous cholesteryl hemisuccinate (CHS)-treated and untreated cells were performed in ten metastatic melanoma patients. In the majority of cases evident reaction was noted with CHS-treated cells (9/10) while the reaction with untreated cells was mostly negative (7/10). Tumour cell suspensions used for skin tests were characterized for reactivity with monoclonal antibody TAL 1B5 detecting the HLA-DR alpha chain. There were no differences between CHS-treated and untreated cells with respect to HLA-DR expression and no correlation was found between grade of skin reaction to CHS-treated cells and the proportion of HLA-DR positive cells in the injected cell sample.