Search

Background: Targeting of cytokines into the tumor sites using antibody-cytokine fission proteins represents a novel approach in cancer immunotherapy. We previously reported a novel monoclonal antibody, FU-MK-1, which recognizes a glycoprotein antigen (termed MK-1 antigen) that is overexpressed on the surface of a majority of carcinomas., Materials and Methods: To target IL-2 and cytotoxicity of effector cells to MK-1-expressing tumor cells, we genetically fused recombinant human interleukin-2 (rhIL-2) to a single chain variable fragment (scFv) antibody derived from FU-MK-1. The resulting fission protein, designated FUscFv/IL-2 was expressed in Pichia pastoris, purified by Ni-affinity chromatography, and characterized for the MK-1-binding specificity and the IL-2 biological activity., Results: The FUscFv/IL-2 fusion protein effectively introduced a specific cytotoxicity of lymphokine-activated killer cells to the tumor cells and consequently suppressed the tumor growth in a SCID mouse xenograft model., Conclusion: This approach may be used for in vivo administration to localize IL-2 to tumor tissues, enhancing the immune response to human MK-1-expressing tumors while reducing systemic side-effects.

Background: This study was designed to determine the effectiveness and toxicity of local continuous immunotherapy for prostatic cancer., Methods: 60 juvenile male Copenhagen rats with Dunning adenocarcinoma of the prostate, implanted subcutaneously into both flanks after proven tumor growth, were treated with either human interleukin-2 (IL-2) depot preparations (n = 30) or albumin (placebo) depot preparations (n = 30) implanted directly next to tumor site. IL-2 depots released IL-2 reliably for more than 24 days. Rat serum was tested during treatment for human IL-2, possibly absorbed from depots, and for rat interferon gamma., Results: IL-2 treatment reduced tumor growth significantly (p < 0.001) compared with albumin treated sites or untreated contralateral sites. No toxicity was observed during treatment. That neither human IL-2 nor rat interferon gamma was detected in serum indicates an exclusively local IL-2 effect., Conclusions: IL-2 depot preparations reduce tumor growth in Dunning adenocarcinoma of the prostate significantly without toxicity.

This study was performed to investigate the direct effects of recombinant human tumor necrosis factor (rH-TNF) and recombinant human interleukin-2 (rH-IL-2), either alone or in combination, on the cytotoxicity of 5-FU measured by MTT assay against human gastric adenocarcinoma cell lines (MKN-28 and MKN-45), and also to determine the optimal schedule for their combination. The antitumor activity of rH-TNF was enhanced more than 42% by 10(2) U/ml of rH-IL-2. The enhancing effects of rH-TNF and rH-IL-2 on the cytotoxicity of 5-FU were evaluated in terms of Modification Index(MI), the MI value at 10 U/ml rH-TNF was 1.6; the MI at the same concentration of rH-TNF in the presence of 10(2) U/ml of rH-IL-2 was 2.1. These results demonstrated that the antitumor effect of 5-FU was enhanced 1.6 times by 10 U/ml of rH-TNF and further enhanced by the combined use of rH-TNF and rH-IL-2. The combined effect of equal concentrations of 5-FU and rH-TNF was superior or equivalent to that of 5-FU or rH-TNF alone. The sequence of 5-FU followed by rH-TNF and rH-IL-2 showed a higher inhibitory effect than the reverse sequence. This sequence combination seems worthy of further consideration for the treatment of gastric cancer.

Cardiac and vascular toxicity of recombinant interleukin-2 (rIL-2) was evaluated by in vitro and in vivo experiments in rats. Using isolated spontaneously beating atria, no changes were detected in heart rate or myocardial contractility in response to rIL-2 treatment at concentrations ranging from 0.1-100 U/ml. Daily sc administration of rIL-2 for 7 consecutive days (at doses of 2.3 X 10(4) to 1.15 X 10(6) U/ml) produced a prolongation of the QaT interval and significant modifications in serum electrolyte concentrations. Ex vivo contractility of atria excised at the end of rIL-2 treatment showed no deterioration in myocardial contractility with increasing dosage. rIL-2, at concentrations of 0.1-1000 U/ml, did not induce any modification of perfusion pressure in isolated rat tail artery but produced a significant displacement to the left of the dose-response curves for norepinephrine compared to basal conditions. The relative potencies were not dose-dependent. Our results indicate that rIL-2 does not exert a direct cardiotoxic effect, and suggest an indirect action on vascular smooth muscle, i.e., an aspecific modulation of vascular response to mediators.