Cancer 1994 Feb 1;73(3 Suppl):824-31

Effect of seven new vasoactive immunoconjugates on the enhancement of monoclonal antibody uptake in tumors.

Khawli LA, Miller GK, Epstein AL.

Department of Pathology, University of Southern California School of Medicine, Los Angeles 90033.

BACKGROUND. To enhance monoclonal antibody uptake in tumors, seven novel vasoactive immunoconjugates were developed that selectively alter the vascular permeability and/or blood volume of tumors in vivo. These immunoconjugates, composed of IL-1 beta, IL-2, TNF-alpha, physalaemin, leukotriene B4, histamine, and bradykinin chemically linked to TNT-1, a murine monoclonal antibody that binds necrotic regions in tumors, have been tested for their effects on antibody uptake in vivo. METHODS. Groups of four mice, each bearing the ME-180 human cervical carcinoma, were pretreated either 3 or 24 hours before the administration of I-125 labeled TNT-1 F(ab')2 fragment. Three-day biodistribution studies then were performed to determine the amount of radiolabeled antibody in the tumors and normal organs of the mice. In addition, mechanism of action studies were performed to determine if the vasoactive immunoconjugate affected the vascular permeability or blood volume of the tumor vessels. RESULTS. TNT-1/IL-2 gave the highest percent injected dose/g in tumor (4.80), compared with TNT-1/TNF (4.00), TNT-1/IL-1 (3.83), TNT-1/leukotriene-B4 (2.84), TNT-1/histamine (2.80), TNT-1/physalaemin (2.19), TNT-1/bradykinin (1.57), or TNT-1 alone (1.28). All of these immunoconjugates showed specific enhancement of monoclonal antibody uptake in tumor with no changes seen in normal tissues. Quantitative studies that demonstrated the mechanism of action of these immunoconjugates showed that TNT-1/IL-2 and TNT-1/histamine produced a marked change in the vasopermeability of tumor vessels but had no effect on tumor blood volume. In contrast, TNT-1/IL-1 and TNT-1/TNF produced a combination of effects, and TNT-1/leukotriene B4, TNT-1/bradykinin, and TNT-1/physalaemin affected only tumor blood volume. CONCLUSIONS. These studies indicate that pretreatment with vasoactive immunoconjugates may improve monoclonal antibody uptake in tumors significantly and thereby increase the therapeutic index of monoclonal antibody-directed immunotherapy.

PMID: 8306266 [PubMed - indexed for MEDLINE]

 

 

Cancer Biother Radiopharm 1996 Jun;11(3):203-15

Improved tumor localization and radioimaging with chemically modified monoclonal antibodies.

Khawli LA, Glasky MS, Alauddin MM, Epstein AL.

Department of Pathology and Radiology, University of Southern California School of Medicine, Los Angeles 90033, USA.

A method for the chemical modification of monoclonal antibodies using the heterobifunctional crosslinker succinimidyl 3-(2-pyridyldithio)propionate (SPDP), has been developed which dramatically alters the physiochemical properties of antibody reagents. For these studies, three murine monoclonal antibodies, B72.3, Lym-1, and TNT-1 were used to demonstrate the effects of chemical modification on clearance and biodistribution in tumor-bearing nude mice. In vitro, all three antibodies, modified to the same degree with SPDP, showed equal immunoreactivities and lower non-specific binding. Modified antibodies also were found to have lower isoelectric points compared to unmodified controls. In vivo, modified antibodies unexpectedly were found to have 2-6 times faster clearance in tumor-bearing nude mice similar to rates obtained with their F(ab')2 fragments. Paired-label in vivo biodistribution and external imaging experiments with intact antibodies and F(ab')2 fragments demonstrated that chemically modified antibodies gave 1.5-3 fold higher tumor uptake and retained less activity in normal organs thus markedly increasing the tumor to normal organ ratios. Because of these results, chemically modified antibodies produced clearer images at earlier time points by external scintigraphy. As "stealth" molecules, chemically modified monoclonal antibodies appear to have significantly improved uptake in tumors and faster clearance times compared to native molecules. These results suggest that alteration of the physicochemical properties of monoclonal antibodies may generate improved reagents for in vivo use.

PMID: 10851539 [PubMed - indexed for MEDLINE]

 

 

Clin Cancer Res 1999 Jan;5(1):51-60

 

Pretreatment with a monoclonal antibody/interleukin-2 fusion protein directed against DNA enhances the delivery of therapeutic molecules to solid tumors.

Hornick JL, Khawli LA, Hu P, Sharifi J, Khanna C, Epstein AL.

Department of Pathology, University of Southern California School of Medicine, Los Angeles 90033, USA.

The efficacy of molecular therapies for human malignancies is limited by inadequate accumulation within solid tumors. Our laboratory has developed a novel approach that uses monoclonal antibodies (MAbs) to direct vasoactive proteins to tumor sites to increase local vascular permeability and, in turn, improve the delivery of therapeutic reagents. Previously, we demonstrated that pretreatment with immunoconjugates containing interleukin-2 (IL-2) enhances specific tumor uptake of radiolabeled MAbs without affecting normal tissues. In the present study, we describe a fusion protein consisting of a chimeric antinuclear antibody and IL-2 (chTNT-3/IL-2) and illustrate its potential for improving the delivery of both MAbs and drugs. The ability of pretreatment with chTNT-3/IL-2 to increase specific tumor uptake of the MAb B72.3 was demonstrated in LS174T colon tumor-bearing mice. Tumor accretion of B72.3 increased nearly 3-fold, with no changes in normal tissues. Abrogation of this effect with N(G)-methyl-1-arginine, a chemical inhibitor of nitric oxide synthase, suggests that rapid generation of nitric oxide in the tumor is responsible for the enhanced uptake. To demonstrate that pretreatment with chTNT-3/IL-2 can improve the uptake of other clinically relevant MAbs in different tumor models, additional studies were performed in both lung and prostate xenograft models. Pretreatment with the fusion protein increased specific tumor uptake of the MAb NR-LU-10 in A427 lung tumor-bearing mice and enhanced tumor uptake of the MAb CYT-351 in LNCaP prostate tumor-bearing mice, 2.1-fold and 1.7-fold, respectively. Finally, tumor uptake of the radiolabeled thymidine analogue 125IUdR also increased approximately 3-fold after pretreatment, indicating that this approach can be extended to small molecules such as chemotherapeutic drugs. Because TNT-3 recognizes a universal nuclear antigen accessible in degenerating and necrotic cells within all solid tumors, this strategy may be applicable to the majority of human cancers.

PMID: 9918202 [PubMed - indexed for MEDLINE]