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SUMMARY 1. The pharmacokinetics of a single dose of Cyclosporine A (CsA) administered to sheep by intravenous (i.v.) route were examined. 2. Concomitant administration of ketoconazole was found to increase the area under the blood CsA concentration-time curve (AUC) and was effective when adminstered by the oral or intraperitoneal route. 3. The effects of CsA and ketoconazole on the immune system of sheep were also assessed. 4. A single dose of CsA 5mg/kg resulted in abrogation of in vitro lymphocyte function manifest at 24h after injection of CsA. Normal responsiveness recovered in 48-72h. Numbers of T lymphocytes in peripheral blood were elevated transiently at 48h although no other significant alteration in lymphocyte subsets was observed with this treatment. 5. Concomitant ketoconazole administration enhanced the CsA-induced suppression of in vitro lymphocyte responses. Blood levels of CsA (AUC values to 24h) were significantly elevated with concomitant ketoconazole administration and depression of lymphocyte responses to mitogens were also significantly enhanced. An increase in the proportion of T4 positive cells in the blood was observed at 48h and at 7 days after administration of CsA with ketoconazole. 6. These findings indicate that CsA effectively abrogates immunocompetence in the sheep and this immunosuppressive effect is enhanced by concomitant administration of ketoconazole.

BACKGROUND Total-body irradiation, followed by hematopoietic system rescue by bone marrow transplantation (BMT), has been found to improve the response of patients with multiple myeloma to treatment with melphalan. The problems of nonhematopoietic toxicity from whole-body irradiation might be circumvented by using a bone-seeking radiopharmaceutical, such as samarium-153 ethylenediaminetetramethylene phosphonate (153Sm-EDTMP), to ablate the bone marrow. PURPOSE A mouse model system for multiple myeloma was used to evaluate the potential therapeutic efficacy of sequential therapy with 153Sm-EDTMP, melphalan, and BMT. METHODS Female C57BL/KaLwRij mice were inoculated with 8 x 10(5) 5T33 murine myeloma cells. Treatment protocols were begun 3 or 10 days later, when the myeloma was either confined to bone marrow or disseminated in liver, spleen, and lymph nodes, simulating human multiple myeloma. 153Sm, a potent beta particle-emitting radioisotope of short half-life (46.7 hours), was linked to the bone-seeking chelate EDTMP. Animals in the first treatment group were each given 22.5 MBq 153Sm-EDTMP via the jugular vein (day 3 or 10), followed by 18.5 mg/kg melphalan (maximum tolerated dose) given intraperitoneally 5 days later (day 8 or 15) and syngeneic BMT another 2 days later (day 10 or 17). Survival in groups of six to 10 animals for each time series was compared with that in mice left untreated (control cohort), in mice treated with 153Sm-EDTMP alone (day 3 or 10), or in mice treated with melphalan alone (day 8 or 15). The hematopoietic systems of animals in the latter two treatment groups recovered full function, obviating the necessity of BMT. The end point was onset of paraparesis, at which time the animals were immediately killed by carbon dioxide asphyxiation. RESULTS Median survival in untreated control animals was 23 days in those with localized disease and 24 days in those with disseminated myeloma. Treatment with 153Sm-EDTMP alone improved survival to a median of 29 days when commenced on day 3 and 30 days when begun on day 10. Melphalan treatment alone improved the median survival to 31 days for animals with localized myeloma and 34 days in animals with disseminated disease. Additional improvement in survival to a median of 42 days was achieved in animals treated 3 days after tumor inoculation with sequential 153Sm-EDTMP, melphalan, and BMT; median survival was 40 days using this regimen in animals with disseminated myeloma. CONCLUSIONS Animals in all three treatment protocols survived longer than those left untreated after inoculation with myeloma cells (P < .001). Sequential treatment with 153Sm-EDTMP, melphalan, and BMT was significantly more effective than single-agent treatment (P < .01). No evidence of radiotoxicity was detected in nonhematopoietic organs. IMPLICATIONS The survival advantage conferred by our sequential treatment protocol suggests its potential clinical usefulness in the treatment of multiple myeloma and other hematologic malignancies in humans.

Malignant mesothelioma (MM) is a tumor that is resistant to conventional therapy. Interferon-α (IFN-α) has been used in the treatment of some human tumors, and we have previously demonstrated an in vitro anti-proliferative effect of IFN against MM cell lines. Therefore, the effect of recombinant human IFN-α (IFN-α2a) (Roferon-A, Hoffmann-La Roche) on previously untreated patients with MM has been studied. Twenty-five patients (24 male and 1 female), with a mean age of 59 ± 9.9 years, were treated for 3 months with IFN-α2a. The starting dose was 3 × 106 IU daily increasing to a maximum of 18 × 106 IU daily or as tolerated. All patients had measurable tumor on thoracic CT prior to commencement. CT scans were performed at 6 and 12 weeks to determine tumor response. Twenty patients completed 3 months of treatment. Five patients were withdrawn because of disease progression. Side effects were predictable and dose related. Dose reductions were necessary in 12 patients for grade 2 toxicity. One patient ...

There is no effective therapy for human malignant mesothelioma, and its susceptibility to recombinant cytokines has not been studied extensively. Recombinant human tumor necrosis factor alpha (rHuTNF alpha) was evaluated for its in vitro and in vivo antitumor activity using a human malignant mesothelioma cell line [DeH128(m)], both in culture and heterotransplanted in nude mice. In vitro, rHuTNF alone had no direct antimesothelioma activity assessed using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay, but in combination with the transcription inhibitor, dactinomycin (AD), mesothelioma cell metabolic activity was inhibited (80% of control). The effects of this combination of agents were studied on DeH128(m) cells heterotransplanted as subcutaneous tumors in nude mice. In vivo there was no significant inhibition of tumor growth by combined rHuTNF alpha and AD therapy, but the combination produced marked cachexia in doses at which each component (rHuTNF alone or AD alone) was well tolerated. The authors conclude that the well-described in vitro interaction between AD and rHuTNF also operates in vivo to produce cachexia and that the combination of these two agents is likely to have a low therapeutic index in malignant mesothelioma.

Malignant mesothelioma arises in serosal tissues, is locally invasive, and is usually resistant to chemotherapeutic agents used clinically. To determine whether resistance to cytotoxic drugs was an inherent characteristic of mesothelioma cells, we performed in vitro chemosensitivity testing on five fully characterised human malignant mesothelioma cell lines and, for comparison, on three lines representative of clinically drug-resistant solid-tissue carcinomas using the MTT (tetrazolium bromide) assay system. Mesothelioma cell lines were intrinsically resistant to eight common antineoplastic drugs, with concentrations that produced a 50% reduction in optical density (IC50 values) for all drugs being equivalent, if not higher, for mesothelioma cell lines as compared with lung and colon carcinoma cell lines. We then investigated the direct anti-mesothelioma activity of recombinant human cytokines with their antineoplastic properties. All five mesothelioma cell lines were resistant to tumour necrosis factor, but they displayed varying degrees of sensitivity to interferons (IFNs). IFN gamma directly inhibited the growth of two of five mesothelioma lines. IFN alpha displayed little activity against four of five mesothelioma lines. The mesothelioma cells that were sensitive to IFN alpha were resistant to IFN gamma, indicating that sensitivity to IFNs is not a genetic characteristic of malignant mesothelioma cells. Significant interactions between cytokines in combination were not observed.

Malignant mesothelioma (MM) is an aggressive tumour of the serosal cavities which is associated with previous asbestos exposure and is generally found to be resistant to conventional forms of therapy. Adequate scientific and clinical assessment of this disease has been severely limited by the relatively low incidence of mesothelioma and the lack of representative cell lines and animal models. The purpose of this study was to develop an asbestos-induced murine model of MM both as an in vivo-passaged malignancy and as in vitro-established cell lines. Such a model system would be invaluable for use in the study of various cellular, molecular and genetic aspects of the disease, and for the pre-clinical evaluation of potential therapeutic agents. BALB/c and CBA mice were injected intraperitoneally with crocidolite asbestos. Seven to 25 months after exposure, 35% of the mice developed mesothelioma (5 BALB/c, 9 CBA), as determined by standard cytological and histological parameters. From these primary tumours, 12 continuously growing cell lines (5 BALB/c, 7 CBA) were established in culture. All have been confirmed as mesothelioma by cytological and ultrastructural (electron microscopy) analyses. These lines have been in culture for 7 to 24 months and have achieved passages above 32 (range 32 to 106). As in the human disease, the murine mesothelioma lines vary in their morphology and growth rates (doubling times ranging from 14 to 30 hr). All cell lines produced tumours when injected into syngeneic mice.