Failure of short-term treatment with flurbiprofen to enhance the therapeutic effect of cyclophosphamide against rodent sarcomas and a leukaemia

The effect of nonsteroidal antiinflammatory drugs ibuprofen, flurbiprofen, and diclofenac on in vitro and in vivo growth of mouse fibrosarcoma

For suppression of primary G:5:113 fibrosarcoma growth, three structurally different cyclooxygenase (COX) inhibitors (ibuprofen, flurbiprofen, and diclofenac) were administered intraperitoneally (i.p.) in two regimens starting on day 5 after tumor-cell inoculation. Repeated application of 0.15 mg/mouse/day during 14 consecutive days significantly suppressed the tumor growth and increased the percentage of surviving mice. Similar tendency, however without significant differences, was observed when animals were given 0.5 mg/day for five consecutive days. These results suggest that a time schedule of drug application is important for the therapeutic effect. Suppressive effect of diclofenac and flurbiprofen on tumor growth was also observed under in vitro conditions. We conclude that suppressive effect of these drugs on tumor growth in vivo comprises both direct effects of COX inhibitors on fibrosarcoma cells and indirect effects that are presumably mediated by extratumoral sources. Our findings encourage the use of COX inhibitors in the therapy of fibrosarcoma.

Inhibition of tumor metastasis by carrageenan-induced granulomas

At -1, 0, +1 weeks from tumor inoculation, carrageenan-impregnated cotton sponges were subcutaneously implanted. Tumor BN472, a malignant adenocarcinoma, was transplanted in syngeneic Brown Norway female rats, either subcutaneously or intravenously. Plasma eicosanoid values (prostaglandin-E2, thromboxane-B2 and 6-keto-prostaglandin-F1 alpha) were determined as well as the cellular immune response (natural killer activity, concanavalin-A and phytohemagglutinin stimulation of spleen lymphocytes). Primary tumor growth and the number of tumor foci in the lungs were measured as parameters of tumor growth and dissemination. No statistically significant differences were observed in primary tumor growth. However, the number of metastatic foci in the lungs of rats in which the tumor was implanted subcutaneously, as well as those in which the tumor was inoculated intravenously, was significantly reduced in those that had carrageenan implanted one week after tumor inoculation. In all other carrageenan-treated groups only slightly reduced numbers of metastatic foci were seen. In those rats with a decreased number of tumor metastatic foci in the lungs, no correlation could be shown with either altered plasma prostaglandin levels, or cellular immune response.

Mechanisms of organ selective tumour growth by bloodborne cancer cells

The sites of tumour development for 6 rat tumours injected into syngeneic rats via different vascular routes was determined. Xenografts of human tumours were also injected intra-arterially (i.a.) into immunosuppressed rats. Following intravenous (i.v.) and intraportal (i.ptl.) injection of cells tumour colonies localized in lung and liver respectively due to tumour cell arrest. Arterially injected radiolabelled cells disseminated and arrested in a similar distribution to cardiac output and did not 'home' to any organs. Following arterial injection of unlabelled tumour cells colonies grew in many organs. While the pattern of growth for a particular tumour varied with the cell dose, the 'arterial patterns' for all of the tumours studied followed a similar pattern. Some organs (eg adrenals, ovaries and periodontal ligament) were consistently preferred, others (eg skin and skeletal muscle) only supported tumour growth following the delivery of large numbers of cells, while in some tissues (eg spleen and intestines) tumour never grew. Viable tumour cells could be demonstrated by bioassay in many organs for up to 24h after i.a. injection. However tumour growth only occurred in certain organs and the pattern of this growth was not related to the number of tumour cells arrested or their rate of autolysis. This site preference could be expressed quantitatively as the probability of an arrested cell developing into a tumour and was considered a 'soil effect'. Site preference was not directly related to organ vascularity. Organ colonisation was promoted by steroid treatment but the mechanism was unclear and was not secondary to T-cell immunosuppression or prostaglandin synthesis suppression. The adrenal glands were preferred sites of tumour growth but pharmacological manipulation of adrenal function did not alter tumour growth to this organ. Sites of injury and healing were preferred sites of tumour colonisation and this could not be accounted for by increased delivery of tumour cells to these regions. The possibility that the macrophage component of the inflammatory response promoted tumour growth was suggested from studies in which the interval between trauma and inoculation of tumour cells was varied as well as by promotion of intraperitoneal (i.p.) tumour growth by a macrophage infiltrate.