Janet H. Ransom

Active specific immunotherapy for stage II and stage III human colon cancer: a randomised trial

BACKGROUND Colon cancer is curable by surgery, but cure rate depends on the extent of disease. We investigated whether adjuvant active specific immunotherapy (ASI) with an autologous tumour cell-BCG vaccine with surgical resection was more beneficial than resection alone in stage II and III colon cancer. METHODS In a prospective randomised trial, 254 patients with colon cancer were randomly assigned postoperative ASI or no adjuvant treatment. ASI was three weekly vaccinations starting 4 weeks after surgery, with a booster vaccination at 6 months with 10(7) irradiated autologous tumour cells. The first vaccinations contained 10(7) BCG organisms. We followed up patients for time to recurrence, and recurrence-free and overall survival. Analysis was by intention to treat. FINDINGS The 5.3 year median follow-up (range 8 months to 8 years 11 months) showed 44% (95% CI 7-66) risk reduction for recurrence in the recurrence-free period in all patients receiving ASI (p=0.023). Overall, there were 40 recurrences in the control group and 25 in the ASI group. Analysis by stage showed no significant benefit of ASI in stage III disease. The major impact of ASI was seen in patients with stage II disease, with a significantly longer recurrence-free period (p=0.011) and 61% (18-81) risk reduction for recurrences. Recurrence-free survival was significantly longer with ASI (42% risk reduction for recurrence or death [0-68], p=0.032) and there was a trend towards improved overall survival. INTERPRETATION ASI gave significant clinical benefit in surgically resected patients with stage II colon cancer. ASI has minimal adverse reactions and should be considered in the management of stage II colon cancer.

Biological and physicochemical characterization of keyhole limpet hemocyanin-lnduced guinea pig lymphotoxin

Abstract Biological and physicochemical properties of keyhole limpet hemocyanin (KLH)-induced guinea pig lymphotoxin (LT) were compared to those of LT induced by another antigen, ovalbumin, or by the mitogen, phytohemagglutinin (PHA). Mitogen- and antigen-induced LT had similar colony inhibitory activities toward guinea pig and rat tumorigenic cells but none toward nontumorigenic cells. Conversely, human nontumorigenic but not tumorigenic cells were inhibited by the three LT preparations. The molecular weight of each LT was 45,000 daltons on gel filtration chromatography but sucrose density gradient ultracentrifugation indicated greater heterogeneity. The KLH-, ovalbumin-, and PHA-induced LTs were resolved into multiple peaks upon preparative column isoelectric focusing (IEF) with IpHs in the range of 4.5 to 5.3. Analytic IEF of the KLH-induced LT revealed the presence of three distinct biologically active peaks with IpH at 4.77, 5.02, and 5.20. LT activity was stabilized during preparative IEF by inclusion of 0.1% polyethylene glycol (4000 molecular weight) in the ampholine gradient. This resulted in 90% recovery of LT activity with a concomitant removal of 96% of the KLH used as the antigenic stimulus for LT production. Fractionation of LT activity during diafiltration and IEF when exogenous proteins were included as protective agents altered the number and the isoelectric characteristics of the peaks obtained suggesting that LT was being bound by the added protein. Colony inhibitory (cytostatic) and 3 H-release (cytolytic) LT activities copurified during fractionation. Thus, this study demonstrated that high yields (approximately 50% of the starting material) of LT, free of antigen or exogenous serum proteins, can be obtained by a combination of diafiltration and IEF performed in the presence of polyethylene glycol.

Control of the carcinogenic potential of 99mTechnetium by the immunologic hormone lymphotoxin.

SummaryImmunologic prevention of the carcinogenicity of the diagnostic gamma-emitting radionuclide 99mTechnetium (99mTc) by lymphotoxin was evaluated using an in vivo-in vitro assay of carcinogenesis. Pregnant Syrian golden hamsters received 125–2,300 μCi 99mTc/kg body weight by injection, and 7 days later colonies of morphologically transformed cells were quantitated in vitro. The transformation frequency increased directly with the radionuclide concentration, and cells derived from transformed colonies produced tumors in athymic nude mice. The total absorbed 99mTc dose was 0.20 rad following injection of 250 μCi 99mTc/kg hamster body weight; this compares with an exposure of 0.13 rad following injection of 143 μCi 99mTc/kg body weight in humans. Intravenous injection of purified hamster lymphotoxin immediately after 99mTc caused a dose-dependent reduction in the transformation frequency. Transformation was essentially completely prevented (97%) by injection of 8,000 U of lymphotoxin. Thus, the immune system, through the action of lymphotoxin, has the potential to prevent carcinogenesis induced by gamma-radiation from 99mTc. This emphasizes the importance of considering the recipients immune and other homeostatic mechanisms as part of a complete diagnostic or therapeutic gamma-radiation regimen.

Selection of Growth Factors and Myelomas To Enhance Monoclonal Antibody-Producing Hybridoma Formation

The potential uses of monoclonal antibodies (Mab) encompass diverse areas in the fields of biology and chemistry, i.e., detecting microbial contamination in food products (1), purifying substances from complex mixtures (2), and identifying and eradicating human cancerous cells (3-5). These are just a few of the reasons substantial work has been directed toward optimizing conditions for production of stable Mab-secreting hybridomas since the first successes in this area were reported in 1975 by Kohler and Milstein (6). Their strategy for producing continuous lines of specific immunoglobulin-producing B-lymphocytes was to fuse them with a myeloma tumor cell. This has been accomplished with immune B-cells from mice, rats (7), and humans (3) fused with myelomas primarily from mice. The specific problems encountered after such a fusion are (1) selection of hybrid cells from nonfused lymphocytes and myelomas, (2) clonal growth hybrids to assure the monoclonality of the antibody being produced, and (3) long term of growth of specific antibody-producing cells. The purpose of this article is to present various means of overcoming these three basic problems. The first of these problems has been dealt with by developing myelomas that are enzyme deficient and can be removed selectively from hybridomas with defined culture medium.

The mechanism of leukoregulin enhancement of target cell susceptibility to NK cell mediated cytotoxicity in humans.

Leukoregulin is an anticancer immunologic hormone or lymphokine whose actions include the inhibition of tumor cell growth and lysis of tumor cells either directly or indirectly by stimulating target cell sensitivity to lysis mediated by natural killer (NK) cells (1, 2, 3). Only a few cell types are directly lysed by leukoregulin and lysis requires very large leukoregulin concentrations. Leukoregulin enhancement of target sensitivity to NK cell cytolysis, however, occurs in the presence of small concentrations of leukoregulin for carcinoma, sarcoma, and leukemia tumor cells (4). Therefore, the primary in vivo means of tumor destruction may be through the combined action of leukoregulin and NK cells.