Molecular biotherapy最新文献

The antitumor activity of recombinant human tumor necrosis factor was studied in vivo as a single agent and in combination with a conventional chemotherapeutic agent. Dosages of tumor necrosis factor of 100 micrograms, 50 micrograms, and 25 micrograms were injected intraportally in Sprague-Dawley rats containing hepatic implants of Walker carcinosarcoma. An effect on the tumor was seen but was associated with a significant acute mortality. Lower dosages of tumor necrosis factor, 10 micrograms, 5 micrograms, and 1 microgram, administered with 10 mg/kg of doxorubicin (Adriamycin) significantly enhanced the antitumor effect of doxorubicin without an acute mortality. This suggests that lower dosages of tumor necrosis factor with conventional chemotherapy may augment the latter's effect without any added toxicity.

Sulfonated derivatives of chitin which showed anticoagulant activity (chitin heparinoids) were studied with regard to the activation of mouse peritoneal macrophages and the production of monokines. In comparison with 70% deacetylated chitin (DAC-70), which was the most adjuvant-active derivative of chitin, all chitin heparinoids were less effective for the augmentation of cytolytic activity of peritoneal macrophages. The number of macrophages was hardly increased or decreased by intraperitoneal injection of chitin heparinoids, and the activity of circulating colony-stimulating factor was not changed by their treatment. Only N-sulfonated DAC-70 stimulated the production of interleukin-1 by thioglycolate-induced peritoneal macrophages in vitro. However, its effect was weaker than that of DAC-70. Chitin heparinoids showed no or weak mitogenic activity on normal mouse spleen cells.

In an effort to improve existing biotherapies, researchers have used recombinant techniques to alter the structure of toxins, monoclonal antibodies, and other receptor and effector molecules. Experimental research has demonstrated that the extent of problems such as nonspecific toxicity and rapid clearance by the immune system are not as great with genetically engineered toxins as opposed to native toxins. Fusion proteins, which combine portions of toxins, antibodies, or various effector molecules, exhibit the preferred biologic properties of their constituents. Unlike their murine counterparts, chimeric antibodies have the ability to invoke cell-mediated immunity and are less immunogenic to humans. Because they display different antigen-binding specificities on the same molecule, hybrid hybridomas are a potential means of juxtaposing effector cells or toxins to tumor cells. These and other positive features of recombinant proteins offer a decided advantage over previous biotherapeutic agents, and these molecules are expected to find application in the treatment of cancer, the acquired immunodeficiency syndrome, and autoimmune diseases.

Thirty eight symptomatic and two asymptomatic patients seropositive for human immunodeficiency virus type-1 (HIV-1) were treated with a natural human interferon alpha (HuIFN alpha). Patients were given 2 IU/kg HuIFN alpha orally once daily in powdered maltose held in the mouth to promote mucosal absorption. This oral immunomodulating HuIFN alpha therapy resulted in an increase in CD4+ lymphocytes, an increase in weight, and a dramatic alleviation of clinical symptoms related to HIV-1 infection.

Antitumor activity, mitogenicity, and lethal toxicity of chemically synthesized lipid A analogs, acylglucosamine-4- or -6-phosphate with the alpha, beta-hydroxyacyl, acyloxyacyl, or hydroxyacyloxacyl groups at the C-2 and C-3 positions, were examined. Meth A fibrosarcoma cells (5 X 10(5)) were inoculated subcutaneously into BALB/c mice on day 0, and six compounds (50 micrograms/mouse) were administered intravenously on days 7 and 9. Although the antitumor activity of these compounds was weaker than that of natural lipopolysaccharide (LPS) or the synthetic lipid A analog (506) of Escherichia sp type, all groups exhibited tumor inhibition rates of 40% to 50% and delayed tumor growth. Six compounds, with the exception of compound A-173 (with the hydroxytetranoyl group at the C-2 and C-3 positions), were capable of increasing the incorporation of [3H]thymidine into cultured splenocytes of C57BL/6 mice, and caused lethal toxicity in C57BL/6 mice sensitized with galactosamine. However, these compounds had lower toxicity than bacterial LPS (about 500- to 1,000-fold). Compounds A-172 and A-174, which have the same structure except for the C-4 or C-6 position of the phosphate group, exerted similar antitumor activity, mitogenicity, and lethality. The results discussed above indicate that the biologic activity of these compounds correlates with the carbon number of fatty acid but is not affected by the different location of the phosphate group. Furthermore, it seems that the difference between the alpha, beta-hydroxy position of fatty acid and the R or S configuration does not alter the biologic effects.

A phase I trial of interleukin-2 and interferon gamma combination treatment in patients with advanced malignancies was performed based on preclinical in vitro and in vivo data which demonstrated synergistic antitumor effect. The toxicities, immune parameters, and tumor responses are described. The clinical and biologic maximal tolerated doses were extrapolated from these data.

Evidence is presented that suggests that PHA-L4 may exert the therapeutic effects of a theoretical ideal biological response modifier through its ability to do the following: to assist remission induction in certain malignancies, to exhibit direct antitumor cytotoxic effects, to enhance antineoplastic effect of radiation and chemotherapy, to decrease the liability to malignant transformation, to promote differentiation and restore normal growth responses in neoplastic cells, to manifest minimal liability to suppressor activity that would inhibit tumor rejection or antitumor cytotoxicity, to repress graft rejection and graft-versus-host responses and amplify the immunosuppressive effects of other agents in allograft transplantations, to display a direct protective effect against damage from radiation and chemotherapy, to stimulate normal myelopoiesis, to reinforce responses against various infections, to amplify tumor immunogenicity, and to attract mononuclear cells to sites of injection or local application.

Human antibody responses to immunotoxin components were evaluated in 21 melanoma patients who were treated with XomaZyme-MEL, a murine monoclonal antimelanoma antibody-ricin A chain conjugate. Twenty of the 21 melanoma patients produced antibodies against ricin A chain, while 15 of 21 produced antibodies reactive with the murine monoclonal antibody component. Both IgM and IgG antibody responses were produced. Immunoglobulin responses were usually detected 1 to 2 weeks following initiation of therapy, with peak levels generally attained 2 to 4 weeks posttherapy. Titers of the anti-ricin A chain antibodies were generally higher than those of the antimurine monoclonal antibodies for the dose range tested. There was no clear correlation between the dose of immunotoxin administered and the antibody titer. By use of a competitive flow cytometry assay, antiidiotype responses were demonstrated in eight of 10 melanoma patients who had antimurine antibodies. Both the kinetics of appearance and the relative titers of the antiidiotype responses generally corresponded to the antimurine responses. The development of antimmunotoxin antibodies can reduce the therapeutic potential of immunotoxins through several mechanisms. The development of antibodies in a significant number of patients suggests that optimally effective, repeated courses of therapy will require some procedure for suppressing or abrogating the response against the immunotoxin.

Seven patients with acute leukemia were treated intravenously with low doses of transferrin-Adriamycin conjugate. The total amount of drug given each patient was far below known toxicity levels for free Adriamycin. The number of tumor cells in peripheral blood diminished in treated patients, and bone marrow aspirates showed no evidence of disease progression. Two patients gave a febrile response and no hypersensitivity reactions were observed. Results of parallel basic research have shown that transferrin receptors on acute leukemia cells bind transferrin-Adriamycin conjugates, and kill by mechanisms at either the plasma membrane or nuclear levels, or both. Such conjugates may provide an alternative to monoclonal antibody drug targeting.

On leukopheresis products obtained from patients included in a protocol interleukin-2/lymphokine-activated killer (IL-2/LAK) cell therapy, we analyzed, in parallel with the standard culture and on large volumes of these products, different parameters which could either improve LAK cell enhancement or simplify the procedure. We demonstrated first that purification of the mononuclear cells from the leukopheresis product before its culture is not required. An excess of red blood cells and granulocytes (up to 50%) in nonpurified samples improved both the mononuclear cell recovery in short-term culture (4 days) and the activation of LAK cells when the total nuclear cell concentration did not exceed 3 X 10(6)/ml. Different factors can contribute to this enhancing effect: the presence of red blood cells, the liberation of cytokines by granulocytes, or the loss of a population of activated lymphocytes, with liberation of cytokines by granulocytes, or the loss of a population of activated lymphocytes, with larger size and density than resting lymphocytes, during the separation. Supplementation of the medium with 2% heat-inactivated autologous plasma obtained before any treatment rather than with 2% pooled human AB serum does not modify the mononuclear cell recovery in 4-day culture, but it does enhance LAK activity. The inhibitory effect of heat-inactivated autologous plasma on proliferation and activation of LAK cells was never observed, suggesting the absence of suppressive factors in the plasma of the 23 analyzed patients. Similarly, autologous plasma did not modify natural killer and LAK cell functions when added during the cytotoxic assay.(ABSTRACT TRUNCATED AT 250 WORDS)