Molecular biotherapy最新文献

We have produced a high-affinity chimeric anti-colorectal carcinoma antibody, ccM4, chimerized in both heavy and light chains by the construction of two expression vectors, the chimeric heavy-chain expression vector mpSV2neo-EP1-Vm4Cr1 and chimeric light-chain vector mpSV2gpt-EP1-VKCK. These vectors contained the neo or gpt gene as a selection marker, the murine immunoglobulin promoter and enhancer (EP1), the genomic DNA fragments of human immunoglobulin constant region (CK and C gamma 1), and murine cDNA fragments of VH and VK region amplified and cloned directly from the B72.3 hybridoma RNA by the polymer chain reaction technique. These two vector DNAs were sequentially transfected into the SP2/0Ag14 cell line. Transfectants were selected in media containing both G418 and mycophenolic acid. The ccM4 antibody was purified from transfectant supernatants with positive binding reactivity for the TAG72 antigen on a protein A column. We demonstrated that ccM4 antibody retained the same high binding reactivity for the TAG72 antigen as its counterpart, the high-affinity chimeric heavy-chain cB72.3m4 antibody. The ccM4 antibody bound specifically to human colon cancer cells, displayed biodistribution patterns similar to cB72.3m4 antibody, and mediated effective antibody-dependent cellular cytotoxicity to human OVCAR3 tumor cells. Therefore, the high-affinity chimeric ccM4 antibody should be useful in cancer immunotherapy.

Mitogenicity, lethal toxicity, and antitumor activity against Meth A fibrosarcoma of chemically synthesized lipopeptide analogs, S-[2,3-bis(palmitoyloxy)-2R-propyl]-N-[(2,2,2)-tri- chloroethoxycarbonyl: Troc group]-cysteinyl-seryl-seryl-asparaginyl-alanine (compound KAB-2), which contain the amino acid sequence of lipopeptide in Escherichia coli, S-[2,3-bis(palmitoyloxy)- 2R-propyl]-N-(Troc- or amino-group)-cysteinyl-asparaginyl-seryl-glycyl-glycine (compound KAB-14 or -20), which is found in the amino acid sequence of lipopeptide in Streptomyces, and the compounds binding one to six amino acids, were examined. The analogs showed the mitogenic activity toward splenocytes of C3H/He mice. Low concentrations (0.4 and 2.0 micrograms/ml) of compounds KAB-20 and -21, which have five and six amino acids, respectively, increased the incorporation of [3H]thymidine better than a high concentration (50 micrograms/ml), suggesting that KAB compounds carrying amino groups exert better mitogenicity than KAB compounds carrying Troc group. The decrease of amino acid number in lipopeptide analogs appears to result in a lowering of mitogenicity at low concentrations. KAB-14 and KAB-2 did not exhibit the lethality at a high dose of 50 micrograms/mouse in galactosamine-loaded C57BL/6 mice. By twice intravenous injections of 50 micrograms against Meth A fibrosarcoma in BALB/c mice, KAB-2 showed a higher inhibitory effect than KAB-14. Based on these results, we concluded that the difference of amino acid sequence in the synthetic lipopeptides affects the potency of biologic activities.

Based on our new finding that an inflammation in which tumor necrosis factor (TNF) is primed or triggered (ontogenic inflammation) can regulate the homeostasis in ontogenesis, we have identified a new lipopolysaccharide from wheat flour (LPSw) that can induce ontogenic inflammation in adult mice. LPSw can prime adult mice to produce TNF when given orally or percutaneously, suggesting that it may maintain homeostasis in adults. LPSw can cure experimental animals of diabetes, hyperlipidemia, ulcer, and herpes. It can also stimulate bone resorption and egg-laying, and shows a strong analgesic effect that is blocked by naloxone. This effect even allows a release from drug addiction. Suppression of serum cholesterol level by oral uptake of LPSw in Watanabe heritable hyperlipidemic (WHHL) rabbit was also observed. Infection of toxoplasma was prevented by oral uptake of LPSw. The realization that a single oral or percutaneous administration of LPSw may be a cure for multiple intractable diseases may lead to the presentation of a nontoxic type of Coley's toxin, which is known to be an efficient cancer treatment, but has high toxicity.

The conference, organized by Profs. Mitrou, Bergmann (Frankfurt), Huber (Mainz) and Niederle (Leverkusen), concentrated almost exclusively on the role of cytokines in cancer. The majority of presentations concerned IFN-alpha, IL 2 or TNF-alpha, but G-CSF, GM-CSF, IL 4, IL 10 and TGF-beta were not neglected. Presentations achieved a laudable balance between basic science and clinically oriented studies. The present report emphasizes the clinical aspects; proceedings of the entire meeting will be published by S. Karger AG, Basel.

Antitumor effect of recombinant human tumor necrosis factor (TNF)-alpha lacking one to three amino acids from the N terminal part (TNFNv3) was tested for its antitumor effect on subcutaneous fibrosarcoma SA-1 tumors. Peritumoral treatment with 5 x 10(4) U TNFNv3 three times every second day significantly delayed tumor growth. Treatment with 10 times higher dose (5 x 10(5) U) produced 6.0 +/- 1.0 days tumor growth delay, but had side effects such as weight loss. The two new desmuramyl N-acyl dipeptides, LK-409 and LK-410, also exhibited such effect; however, the tumor growth delay was barely significant. The treatment was performed with two concentrations (2.5 micrograms and 25.0 micrograms) applied intraperitoneally for 5 consecutive days, without a dose-dependent effect. Combined treatment with TNFNv3 and desmuramyl dipeptides augmented the antitumor effect of treatments. The effect was additive and significant in the combination of 2.5 micrograms LK-410 with 5 x 10(5) U TNFNv3. LK-410 treatment also reduced the side effects of TNFNv3. The results indicate that combined treatment with both biological response modifiers is effective in tumor treatment.

We evaluated density of the natural killer (NK) cell-associated CD56 antigen on circulating NK cells of 47 patients with advanced renal cell carcinoma. Patients received a combination of low-dose subcutaneous recombinant interleukin-2 (rIL-2) and recombinant interferon-alpha (rIFN-alpha) as home therapy. Antigen density of CD56 before therapy was 2.2-fold higher (P < 0.005) in patients who subsequently achieved a complete or partial remission when compared with patients who presented with progressive disease on therapy. After a 6-week treatment cycle, NK cells of treatment responders expressed significantly (2.1-fold; P < 0.005) more CD56 antigens than NK cells in nonresponding patients. These results suggested a potential role of both pre- and posttreatment NK antigen density levels as a biologic correlate to treatment response.

The goal of Phase I clinical trials is to establish a maximum tolerated dose (MTD) and a tolerable dose range for future efficacy testing. Various issues include schedule of drug delivery, starting dose, number of patients to be tested, pitfalls in the selection of MTD, risk:benefit ethical issues, and the problems introduced by patient heterogeneity. Statistical evaluation of various Phase I strategies illustrate the limitations of various approaches in terms of patient expectations regarding efficacy and the scientific goals of such trials. Patients should be given the opportunity to receive the drug at more than one single dose level.

Toxins may be specifically directed to tumor cells and the toxins' potency greatly increased by covalent conjugation to monoclonal antibodies recognizing tumor-associated antigens. Antibody 15A8, an immunoglobulin G1 (IgG1) subclass anti-human breast carcinoma murine monoclonal antibody and gelonin, a plant toxin, were covalently modified with N-succimindyl 3-(2-pyridyldithio) proprionate and iminothiolane, respectively, and allowed to cross-link. 15A8-gelonin conjugates were purified from unreacted antibody and free gelonin by gel filtration and blue sepharose chromatography. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the final product contained two bands corresponding to antibody:gelonin conjugates of 1:1 (predominant) and 1:2. There were no contaminating amounts of free antibody or free toxin in the preparation. The yield of the final purified 15A8-gelonin conjugate was approximately 20% based on the amount of starting antibody. The protein synthesis inhibitory activity of the immunoconjugate was assessed by in vitro rabbit reticulocyte translation assay. This functional activity was normalized to that of unmodified gelonin for use in in vitro antiproliferative assays against antigen-negative (Hs294t human melanoma) and antigen-positive (ME-180 human cervical carcinoma) cell lines. Antigen-negative Hs294t cells incubated for 72 hours with 15A8-gelonin immunotoxin showed no increased cytotoxicity compared with HS294t cells exposed to free gelonin alone. However, the immunotoxin was preferentially toxic to antigen-positive ME-180 cells; over 5 logs greater cell kill was observed after 72 hours exposure to 15A8-gelonin than after the same exposure to gelonin alone. Various lysosomotropic agents augmented 15A8-gelonin cytotoxicity; the most effective potentiating agent appeared to be monensin. In addition, the chemotherapeutic agents L-phenylalanine mustard (L-PAM), 5-fluorouracil, vincristine, and bleomycin, and the biological response modifiers interferon-alpha and tumor necrosis factor-alpha were shown to augment 15A8-gelonin cytotoxicity. Should in vivo pharmacology and therapeutic studies confirm these in vitro findings, 15A8-gelonin conjugate may be a potent agent for therapy of cancer in man.