Experimental screening of BCG preparations produced for cancer immunotherapy: safety and immunostimulating and antitumor activity of four consecutively produced batches

Design of immunoliposomes directed against human ovarian carcinoma

Factors (protein/lipid ratio, pH of incubation medium, incubation time, anchor molecule density in the bilayer) affecting the covalent binding of anti-ovarian carcinoma Fab' to liposomes containing the anchor molecule MPB-PE (N-(4-(p-maleimidophenyl)butyryl)phosphatidylethanolamine) were explored. Standard experimental conditions were chosen and information on the relevant physicochemical parameters of the liposome dispersions was collected (mean particle diameter, size distribution, charge). The reproducibility of standard immunoliposomes prepared in subsequent batches in terms of Fab' binding, particle size and charge was established. In addition, preservation of immunoreactivity, no marker loss, and no aggregation/fusion was found for the standard immunoliposomes over a period of at least 3 weeks at 4 degrees C. In vitro up to 35,000 immunoliposomes were estimated to bind per human ovarian carcinoma cell. Internalization of the immunoliposomes could not be demonstrated. Electron micrographs showed binding of specific immunoliposomes to human ovarian carcinoma cells growing intraperitoneally in athymic nude mice.

Impaired immune response by isoniazid treatment during intravesical BCG administration in the guinea pig

At present, isoniazid (INH) is being used prophylactically to reduce the side effects of intravesical BCG therapy for superficial bladder cancer, although it is not clear whether or not this reduces the antitumor efficacy of BCG. In this study the impact of INH treatment on the immune response after repeated intravesical BCG administration was investigated in guinea pigs. INH was given on the 3 days around each BCG instillation. We found that the administration of INH severely impaired the immunological effects of BCG. The induction of mononuclear cell infiltration in the bladder wall was reduced. Enlargement of the regional lymph nodes (weight and number of cells), and increase of MHC Class II expression on the lymph node cells, normally observed after intravesical BCG administration, were inhibited by INH. Systemic immunity, measured by the DTH reaction in the skin to PPD, was also diminished due to the combined treatment of BCG with INH. When INH was administered during the last 4 of 6 BCG instillations, the immune response to BCG was still impaired. A five-fold increase of the dose of BCG did not overcome the effect of INH. INH probably did not exert a direct suppression of the immune system of the guinea pig as the DNCB skin reactivity was not influenced. Although INH concentrations in the urine were high at the onset of the instillation, in vitro experiments indicated that the effect of INH may not be caused by killing of the BCG organisms shortly after application in the bladder. In conclusion, our data in guinea pigs suggest that the use of INH may impair the immune response to intravesical BCG. As this response may be important for the antitumor effect of BCG, urologists should be cautious with the prophylactic use of INH. The influence on the antitumor efficacy is now investigated in man.

Immunotherapy of bovine ocular squamous cell carcinoma by repeated intralesional injections of live bacillus Calmette-Guérin (BCG) or BCG cell walls

Thirty cows of the Dutch Friesian and the Maas-Rijn-Ijssel breed with histologically confirmed ocular squamous cell carcinoma were treated by repeated intralesional injection of live bacillus Calmette-Guérin (BCG) (n = 14) or a BCG cell-wall vaccine (n = 16). Complete regression of the primary tumour was observed in 64% and 57% of the animals respectively. In the 2-year follow-up period there was no recurrence of primary tumours. This sharply contrasts with the recurrence frequency (40%-50%) after complete remission induced by a single intralesional injection with BCG, observed in an earlier study. In 1 animal a new primary tumour developed. At necropsy metastases were present in 33% of the treated animals: in 3 of 17 animals that showed complete regression of the primary tumour and in 7 of 13 animals with partial regression or progressive disease. This did not differ significantly from results obtained after a single treatment (27%). Delayed-type hypersensitivity to M. bovis purified protein derivative (PPD) was more persistent in animals showing regression of the primary tumour than in non-responding animals. Of the animals with a positive PPD response 6 months after treatment, 79% showed tumour regression. Regression was observed in only 28% of the animals not responding to PPD after the same period of time.

IN CONCLUSION

(a) recurrence of the primary tumour was not observed after repeated BCG treatment; (b) the frequency of metastases was not decreased compared to results obtained with a single treatment; (c) regression was correlated with a positive delayed-type hypersensitivity reaction to PPD (P less than 0.05) 6 months after treatment; (d) no significant differences were observed when the clinical results of treatment with live BCG and the BCG cell wall vaccine were compared.

Major histocompatibility complex class II antigen expression on leucocyte subpopulations in the draining lymph node and tumour in the early phase of bacillus-Calmette-Guérin-induced tumour regression

We investigated the cellular composition and the major histocompatibility complex (MHC) class II antigen expression in the draining lymph node and the tumour during potentiation of the immune response by intralesional bacillus Calmette-Guérin (BCG) administration in the line 10 hepatocellular carcinoma in the strain 2 guinea-pig. Five days after its injection BCG induced a ninefold increase in the number of draining lymph node cells and an increased MHC class II expression. This increased MHC class II expression was mostly due to the selective increase of B cells in the lymph nodes, and to a lesser extent to the increase of T cells expressing MHC class II antigens. Taking into account this nine-fold increase, intralesional treatment of BCG increased considerably the number of T helper/inducer (anti-CT7) and T suppressor/cytotoxic (anti-CT6) lymph node cells expressing MHC class II antigen. The percentage of tumour-infiltrating T cells expressing MHC class II antigen in the tumour was higher than the percentage of T cells in the regional draining lymph node of non-treated guinea-pigs, indicating the presence of activated T cells in the tumour. After treatment with BCG no further increase in MHC class II expression was measured in the tumour, nor was any phenotypical change of the tumour-infiltrating T cells found. In conclusion, with the use of two-colour flow cytofluorometry we have shown that the potentiation of the already existing immune response to line 10 is accompanied by a considerable increase in T helper/inducer, T suppressor/cytotoxic cells and MHC class II antigen in the regional lymph node. Whether this is essential for the potentiation of the immune response causing tumour regression and long-lasting immunity is a subject for further study.

Tumour rejection after adoptive transfer of line-10-immune spleen cells is mediated by two T cell subpopulations

The growth of line-10 tumours in naive guinea pigs is prevented by adoptive transfer of spleen cells that are hyperimmune to this hepatocellular carcinoma. To study the T cell subpopulations responsible for the adoptive transfer of immunity, various cell populations were removed from immune spleen cells using monoclonal antibodies (mAbs) and magnetic microspheres. Spleen cell subpopulations were identified by mAb after flow cytometry and rosette formation with the magnetic microspheres. mAb CT5 was confirmed to be a pan T cell marker, while the CT6 (anti-T-suppressor/cytotoxic) and CT7 (anti-T-cell) markers were present on two different T cell subpopulations. So our results show that CT7 mAb cannot be used as a pan T cell marker as was published previously. Moreover, the mAb H155 (anti-T-helper/inducer) reacted with the same T cell subpopulation recognized by CT7. So we designated this H155/CT7-positive subpopulation as T helper/inducer cells. Removal of the CT6-, CT7-, or the H155-positive T cells from the immune spleen cells resulted in loss of the in vitro proliferative response to line-10 tumour protein and tuberculin purified protein derivative (PPD). The H155/CT7 (anti-T-helper/inducer)-positive spleen cells did not express MHC class II antigens as determined by mAb 25E3. In most experiments, elimination of MHC-class-II-positive cells did not change the in vitro proliferative response to line-10 protein, whereas the response to tuberculin PPD was completely abrogated. Immune spleen cells after depletion of CT6-, CT7- or H155-positive cells, failed to transfer immunity. However, after depletion of MHC-class-II-antigen-positive cells the line-10 immunity was still present, whereas the immune response to tuberculin PPD was lost. In conclusion, our data indicate that immunity to the line-10 tumour is the result of a cooperation between at least two different T cell subpopulations, the T helper/inducer (CT7/H155) cells and the T suppressor/cytotoxic cells (CT6). If this is a common feature, then the therapeutic approach of in vitro expanded TIL cells should take into consideration the requirement of two T cell subsets.

Tumor infiltrating leukocytes (tils) during progressive tumor growth and BCG-mediated tumor regression

Tumor regression was induced by intralesional injection with BCG, 7 days after inoculation of line 10 hepatocellular carcinoma cells into strain 2 guinea pigs. Tumor-infiltrating leukocytes (TILS) were characterized immunohistochemically with 11 monoclonal antibodies (MoAbs) during the induction phase of line 10-immunity, and during immune-mediated regression of the tumor, at days 12 and 28 after tumor cell inoculation, respectively. At day 5 after BCG-injection (day 12 after tumor cell inoculation), there were no major differences between the TIL subpopulations of the BCG-treated and untreated tumors. The TILS were mainly T-cells, as identified by MoAbs against Pan T-cells (CT5), T-cytotoxic/suppressor cells (CT6) and T-helper/inducer cells (H155). A limited number of macrophages was also present. However, at day 21 after BCG-treatment (28 days after tumor cell inoculation), the fibrous stroma was increased dramatically in most of the BCG-treated tumors, and as a result, the tumor cell islets were smaller than in control tumors. In the BCG treated tumors, the numbers of T-cells and macrophages were increased. In growing and regressing tumors, MHC class I and II antigens were strongly expressed in TILS and in the tumor stroma. Line 10 tumor cells prior to inoculation expressed no MHC class I or II antigens. In the centers of the tumor islets at days 12 and 28, expression of these antigens was not found. However, MHC class I and II antigens were expressed on tumor cells at sites where they lay close to the fibrous stroma or TILS. This observation was made in progressively growing tumors and was most apparent in BCG-treated tumors.

Presence of interleukin-2 in urine of superficial bladder cancer patients after intravesical treatment with bacillus Calmette-Guérin

Urine samples were obtained from patients with superficial bladder cancer after immunotherapy with bacillus Calmette-Guérin (BCG). The patients were repeatedly (once a week for 6 consecutive weeks) treated with intravesical administration of approximately 5 X 10(8) culturable particles of BCG. Some patients received more than six BCG instillations. The urine samples were investigated for the presence of interleukin-2 (IL-2) in an in vitro bioassay using a murine cytotoxic T cell line (CTTL-16) that shows IL-2-dependent growth. Preliminary experiments indicated the presence of inhibitory factors in the urine. This inhibitory activity was abolished after 24 h dialysis. In a neutralization assay with both polyvalent and monoclonal anti-(human IL-2) antibody it was demonstrated that there was indeed IL-2 in the urine samples. In 8 of 11 patients the presence of IL-2 in the urine was demonstrated. The IL-2 production was directly related to the BCG administration as samples obtained just before the BCG instillation were always negative. In IL-2-positive samples a maximum level of IL-2 was observed between 2 h and 6 h after the BCG instillation. In urine samples obtained 24 h after the BCG IL-2 was not detected. In most patients the urine became positive after the third or fourth PCG instillation.

Major-histocompatibility-complex-class-II-positive cells and interleukin-2-dependent proliferation of immune T cells are required to reject carcinoma cells in the guinea pig

Tumor immunity induced by bacillus Calmette-Guérin was studied in the line 10 hepatocellular carcinoma (line 10) in the strain-2 guinea pig. Line 10 immunity was investigated in vitro with a lymphocyte proliferation assay using line 10 tumor protein extracted with 3 M KCl and in vivo by adoptive transfer of line-10-immune spleen cells. Monoclonal antibodies against guinea pig leucocyte markers were used to block functional properties of the immune cells in order to determine which cell types or cell markers are involved in the immune response to the line 10 tumor. In vitro cells from the spleen, peripheral blood and regional lymph node of immune animals reacted with a proliferative response to line 10 protein. This antigen-specific response was caused by T cells and was regulated by major histocompatibility complex (MHC) class II molecules. In blocking experiments it was found that CT5 (anti-PanT), or MSgp4 [anti-(MHC class I antigen)] monoclonal antibodies did not block but sometimes stimulated the proliferative response. The effect of H159 (anti-PanT) was irregular, while H155 [anti-(T helper)], and 5C3 [anti-(IL-2 receptor)] monoclonal antibodies blocked the response almost completely. We studied the relevance of the results in vitro obtained and found that mAb 5C3 [anti-(IL-2 receptor)] inhibited the adoptive transfer of line 10 immunity, suggesting that the rejection of line 10 cells is caused by a mechanism that is interleukin-2 (IL-2)-dependent. Moreover, complement lysis of MHC-class-II-antigen-positive immune spleen cells inhibited completely the rejection of the line 10 tumor cell challenge in the adoptive-transfer experiments. In conclusion, our data show that MHC class II molecules or cells possessing these molecules are involved in immunity against line 10 tumor cells, as (a) monoclonal antibodies against MHC class II antigens inhibited the in vitro proliferative response of T cells to tumor antigens and (b) removal of MHC-class-II-positive immune spleen cells abrogated the antitumor effect in the adoptive-transfer experiments. Interleukin-2-dependent proliferation of immune T cells is required for the rejection of line 10 tumor cells.

Intravesical BCG administration in the guinea pig. A histomorphological study

Intravesical BCG administration is used as an adjuvant therapy after transurethral resection for superficial bladder cancer in man. The mechanisms of its antitumor activity are not known. The aim of this study was to characterize the histomorphological changes in various organs of the guinea pig after intravesical BCG administration. The BCG preparation used was BCG-RIVM, a Dutch BCG preparation. Instillations were performed in previously undamaged bladders weekly for 6 consecutive weeks and lasted 30 min or 1 h. Different doses were used ranging from 10(3) culturable particles (c.p.) to 5 x 10(7) c.p. of BCG. After 6 weeks, the animals were killed and postmortem examination was performed. The bladder wall, retroperitoneal lymph nodes, spleen, liver, lungs and distant lymph nodes were examined histologically. The BCG therapy, with a dose of 10(6) culturable particles and higher, induced an inflammatory reaction consisting of mononuclear infiltrates in the subepithelial tissue of the bladder wall. In approximately 50% of the animals investigated, the infiltrates were accompanied by non-caseating granulomatous lesions indicated by the presence of epithelioid cells. In general, the epithelial layer of the bladder showed no visible alterations. Similarly, a granulomatous inflammatory reaction was observed in the first retroperitoneal (iliac) lymph nodes draining the bladder. Granulomatous lesions were occasionally also present in liver and lung. In three of the 29 animals investigated, lesions were present both in liver and lungs, and in two of these three animals a granulomatous reaction was observed in the spleen and distant lymph nodes indicating a generalized inflammatory response induced by BCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Potential pitfalls in in vitro antitumor activity testing of free and liposome-entrapped doxorubicin

This paper addresses several potential problems which may play a critical role in the outcome of in vitro studies designed to investigate the antitumor activity of drugs. These problems were demonstrated to exist in in vitro assays developed for the evaluation of antitumor activity of free and liposome-entrapped doxorubicin (DXR). The stability of DXR-containing liposomes against drug leakage into the culture medium, as well as the chemical stability and extent of adsorption to tissue culture plastics of both free and liposomal DXR during the liposome-tumor cell incubation, were investigated. It is concluded that a full understanding of these processes is required for a reliable interpretation of the experimental results.

Release of doxorubicin from peritoneal macrophages exposed in vivo to doxorubicin-containing liposomes

Intracellular depot formation may be an important component of the mode of action of doxorubicin (DXR)-containing liposomes. In this paper it was investigated whether it is possible that DXR is released from macrophages which have taken up DXR-containing liposomes in vivo. Macrophages were harvested from the peritoneal cavity of LOU/M rats after i.p. administration of DXR-liposomes. Two different liposome types were used for this investigation. The amount of DXR associated with macrophages was determined by high performance liquid chromatography. In order to monitor DXR release from the macrophages, an in vitro tumor cell growth inhibition assay was applied. Peritoneal macrophages collected 24 h after an i.p. injection of DXR-liposomes (10 mg/kg body weight) caused considerable growth inhibition of tumor cells in culture. The cytostatic potential of macrophage monolayers in vitro depended on the type of injected DXR-liposomes and was directly related to the amount of macrophage-associated DXR. The DXR content of the macrophage monolayers was completely released from the cells into the culture medium during the cocultivation with tumor cells. Supernatants obtained from monolayers, which were cultivated in the absence of tumor cells, showed a high growth-inhibitory activity. DXR either free or in liposomal form was chemically stable for up to 26 h during incubation with lysosomal fractions isolated from rat liver homogenates. The results indicate that release of DXR from macrophages which have phagocytosed DXR-liposomes in vivo is a real possibility.

Histological evaluation of immunologically mediated tumor regression of the line 10 guinea pig hepatocarcinoma

The histology of immunologically mediated tumor regression was studied in the syngenic strain 2 guinea pig/line 10 hepatocellular carcinoma tumor system. Tumor regression was induced non-specifically by the intralesional injection of living Bacillus Calmette-Guérin (BCG) in 7-day-old established tumors (diameter 8-10 mm). In untreated line 10 tumors at day 7 a mild to moderate inflammatory reaction was present, which consisted mainly of small mononuclear cells; in addition large mononuclear cells and basophils were present. Intratumoral BCG-treatment induced a prominent increase in the inflammatory reaction due to an influx of small and large mononuclear cells and neutrophils. Small mononuclear cells were identified mainly as lymphocytes whereas large mononuclear cells belonged mainly to the macrophage line. Intratumoral administration of BCG resulted in a granulomatous reaction. A time-related decrease in the number of tumor cells and an increase in inflammation, associated with purulent lysis of the granulomatous tissue, was observed. Specific immune-mediated tumor rejection occurred in animals both after active immunization and after adoptive transfer of immune spleen cells. In actively immunized animals the tumor cells were rapidly rejected and from day 4 onwards no tumor cells could be detected at the injection site. Lymphocytes were the major component of the inflammatory reaction; large mononuclear cells were present to a lesser extent and basophilic granulocytes were regularly observed. After adoptive transfer of immunity with immune spleen cells given simultaneously with an intradermal innoculation of tumor cells, an essentially similar rejection reaction was found, although tumor cell rejection was delayed. Lymphocytes and large mononuclear cells were found in equal proportions, whereas basophilic granulocytes were always present in smaller numbers. After BCG-induced regression and in adoptively transferred immune rejection, a fibroblast component was more prominent than in untreated control tumors. This reaction tended to isolate smaller tumor cell areas into islets of decreasing sizes. In contrast with the fibroblast component of growing tumors, the proliferative pre-existing fibrous tissue in tumors undergoing regression or rejection showed a loosely arranged architecture and contained a marked cellular infiltrate. From the results of the present study it was concluded that the morphological expression of line 10 tumor rejection varies. Without immune cells, BCG is needed for the induction of a local inflammatory reaction, which was granulomatous in type and eventually led to complete tumor cell eradication.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of intravesical and intradermal application of a new B.C.G. on the dog bladder

Intravesical and intradermal application of B.C.G. (Bacillus Calmette Guérin) has proven to be effective in the prophylaxis of recurrence of superficial bladder carcinoma after transurethral resection and in the treatment of carcinoma in situ (C.I.S.) in man. Different strains of B.C.G. have been used for this purpose. In this article a new strain of B.C.G. (B.C.G.-R.I.V.M.) has been tested to assess its toxicity. The effects of intravesical and intradermal application of B.C.G.-R.I.V.M. were studied on normal and on coagulated canine urothelium. In this study no general side effects of B.C.G.-R.I.V.M. were seen. Only minor local changes occurred in the bladder wall. Small granulomas were found in the suburothelial tissue. No granulomas or signs of active inflammation were observed in the pelvic lymphnodes, spleen and liver. Because B.C.G.-R.I.V.M. seemed to be a safe agent in the dog we have started to use it for prophylaxis in superficial bladder cancer in man.

Experimental screening of BCG preparations produced for cancer immunotherapy: safety and immunostimulating and antitumor activity of four consecutively produced batches

Four consecutively produced batches of Bacillus Calmette-Guérin (BCG) especially intended to be used for cancer immunotherapy were investigated for consistency of the vaccine. Each batch was investigated directly after production of the vaccine, so that the four batches were not tested simultaneously. The activity of the four batches was investigated in general safety assays, immunostimulation assays, and two different tumor models. General safety assays showed dose-dependent growth retardation and increased serum glutamic pyruvic transaminase activity in mice, and a long-lasting temperature rise in rabbits after IV administration of the BCG preparations. In a skin reactivity assay, reactions were found acceptable for all preparations when compared with a reference batch. The results of the immunostimulation and antitumor studies can be summarized as follows. All four batches induced a specific delayed-type hypersensitivity reaction to PPD, indicating the induction of cell-mediated immunity. A stimulating effect on lymphoreticular organs was concluded from increased spleen weight and enhanced cell proliferation in draining lymph nodes. Enhanced macrophage function (phagocytosis and killing of bacteria) was demonstrated by an increased resistance to Listeria monocytogenes. YAC lymphoma target cells were killed nonspecifically by BCG-activated peritoneal exudate cells (PEC), indicating the induction of natural killing activity by BCG. Intralesional injection of BCG induced tumor regression in the guinea pig line 10 hepatocellular carcinoma, followed by immunity to the line 10 tumor. In the murine 5D04 squamous cell carcinoma, BCG had no effect on the primary tumor. However, IV-injected BCG resulted in a decreased number of lung metastases. In general, the four consecutively produced batches showed similar safety and activity in the immunostimulation assays and antitumor activity. Since only minor differences between the batches were found, which can also be attributed to the variation in experimental conditions common to biological assays, it is concluded that the vaccine batches produced show an acceptable consistency.