Tumor localization and in vivo antitumor activity of the immunoconjugate composed of anti-human colon cancer monoclonal antibody and mitomycin C-dextran conjugate

Translational research of new developments in targeted therapy of colorectal cancer

A severe global health concern is the rising incidence and mortality rate of colorectal cancer (CRC). Chemotherapy, which is typically used to treat CRC, is known to have limited specificity and can have noticeable side effects. A paradigm shift in cancer treatment has been brought about by the development of targeted therapies, which has led to the appearance of pharmacological agents with improved efficacy and decreased toxicity. Epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER2), and BRAF are among the molecular targets covered in this review that are used in targeted therapy for CRC. The current discussion also covers advancements in targeted therapeutic approaches, such as antibody-drug conjugates, immune checkpoint inhibitors, and chimeric antigen receptor (CAR) T-cell therapy. A review of the clinical trials and application of these particular therapies in treating CRC is also done. Despite the improvements in targeted therapy for CRC, problems such as drug resistance and patient selection remain to be solved. Despite this, targeted therapies have offered fresh possibilities for identifying and treating CRC, paving the way for the development of personalized medicine and extending the life expectancy and general well-being of CRC patients.

Role of pharmacokinetic consideration for the development of drug delivery systems: A historical overview

Drug delivery system is defined as a system or technology to achieve optimum therapeutic effects of drugs through precise control of their movements in the body. In order to optimize function of drug delivery systems aiming at targeting, their whole-body distribution profiles should be systematically evaluated and analyzed, where pharmacokinetic analysis based on the clearance concepts plays important role. Organ perfusion experiments combined with statistical moment analysis further supply detailed information on drug disposition at organ and cellular levels. Based on general relationship between physicochemical properties and distribution profile, macromolecular prodrugs or polymer conjugates of proteins are rationally designed and further introduction of ligand structure brings cell-specific delivery for them. These approaches are also applicable for particulate carriers such as liposomes and offer various opportunities for biological drugs such as nucleic acid drugs for their delivery. Mechanistic approach for dermal absorption analysis based on physiological skin model offers another opportunity in rational design of drug delivery. Potential of drug delivery technology in future medicines such as cell therapy and nanomaterial platform application is further discussed in relation to pharmacokinetic consideration.

Preparation of a PLA–PEG block copolymer using a PLA derivative with a formyl terminal group and its application to nanoparticulate formulation

A novel poly(DL-lactic acid) (PLA) derivative with a diethoxy propanol ester at the end, named PLA-acetal, was synthesized by ring opening polymerization using DL-lactide and 3,3-diethoxy propanol. PLA-acetal was hydrolyzed to a PLA derivative with a formyl group, named PLA-aldehyde, by acid treatment. Reductive amination between PLA-aldehyde and methoxypolyethylene glycol amine (MeO-PEG(N)) gave the block copolymer (PLA-(MeO-PEG(N))). Nanoparticles were prepared by emulsification-solvent evaporation or solvent diffusion using PLA-(MeO-PEG(N)) or a conventional methoxypolyethylene glycol-PLA block copolymer, PLA-(MeO-PEG(O)). PLA-(MeO-PEG(N)) nanoparticles had a particle size of 60-340 nm, dependent on the preparative procedure, while PLA-(MeO-PEG(O)) nanoparticles prepared by solvent diffusion showed a particle size of 60 nm. The PLA-(MeO-PEG) nanoparticles with a smaller PEG introduction degree exhibited a more negative zeta potential. 1,1'-Dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine perchlorate (DiD) could be incorporated efficiently in PLA-(MeO-PEG(N)) nanoparticles. It is suggested that PLA-aldehyde should be useful as a functional intermediate for derivatization of PLA, and PLA-(MeO-PEG(N)) can be used for the preparation of PEG-coated PLA nanoparticles.

Tumor targeting of gene expression through metal-coordinated conjugation with dextran

Tumor targeting of plasmid DNA was achieved through the conjugation of dextran derivatives with chelate residues based on metal coordination. Diethylenetriamine pentaacetic acid (DTPA), spermidine (Sd), and spermine (Sm) were chemically introduced to the hydroxyl groups of dextran to obtain dextran-DTPA, dextran-Sd and dextran-Sm derivatives. Conjugation of the dextran derivative by Zn(2+) coordination decreased the apparent size of the plasmid DNA, depending on the derivative type. The negative zeta potential of plasmid DNA became almost 0 mV after Zn(2+)-coordinated conjugation with dextran-Sm. When the dextran derivative-plasmid DNA conjugates with Zn(2+) coordination were intravenously injected subcutaneously into mice bearing Meth-AR-1 fibrosarcoma, the dextran-Sm-plasmid DNA conjugate significantly enhanced the level of gene expression in the tumor, in contrast to the conjugate of other dextran derivatives and free plasmid DNA. The enhanced gene expression produced by the Zn(2+)-coordinated dextran-Sm-plasmid DNA conjugate was specific to the tumor, whereas a simple mixture of dextran-Sm and plasmid DNA was not effective. The level of gene expression depended on the percentage of chelate residues introduced, the mixing weight ratio of the plasmid DNA/Sm residue used for conjugate preparation, and the plasmid DNA dose. A fluorescent microscopic study revealed that localization of plasmid DNA in the tumor tissue was observed only after injection of the dextran-Sm-plasmid DNA conjugate with Zn(2+) coordination. In addition, the gene expression induced by the conjugate lasted for more than 10 days after the injection. We conclude that Zn(2+)-coordinated dextran-Sm conjugation is a promising way to enable plasmid DNA to target the tumor in gene expression as well as to prolong the duration of gene expression.

Antitumor activities of conjugates of mitomycin C with estradiol benzoate and estradiol via glutaric acid in suspension dosage form

Conjugates of mitomycin C (MMC) with estradiol bezoate and estradiol via glutaric acid (EB-glu-MMC and E-glu-MMC, respectively) were examined for their antitumor activities against P388 leukemia and sarcoma 180. EB-glu-MMC and E-glu-MMC were suspended in 10% (v/v) propylene glycol in saline and administered intraperitoneally to mice bearing P388 leukemia intraperitoneally or to mice bearing sarcoma 180 subcutaneously. The antitumor effect against P388 leukemia was greater in the order MMC>E-glu-MMC>EB-glu-MMC, and only the former two compounds significantly increased life span. On the other hand, EB-glu-MMC and E-glu-MMC showed suppression of sarcoma 180 growth at higher doses close to or better than MMC. In the mixture of 1/15 M phosphate buffer (pH 7.4, ionic strength (mu) adjusted to 0.3 with NaCl)-propylene glycol (9:1, v/v) at 37 degrees C, MMC was released much more slowly from EB-glu-MMC suspension than from E-glu-MMC suspension. With regard to chemotherapy against sarcoma 180, both conjugates were considered to supply MMC slowly but effectively at higher doses.

Synthesis and pharmacokinetics of a novel macromolecular prodrug of Tacrolimus (FK506), FK506-dextran conjugate

A novel macromolecular prodrug of Tacrolimus (FK506), FK506-dextran conjugate, was developed and its physico-chemical, biological and pharmacokinetic characteristics were studied. The conjugate was estimated to contain 0.45% of FK506 and the coupling molar ratio was approximately 1:1 (dextran-FK-506). Adsorption experiments using ion exchangers indicated that FK506-dextran conjugate acted as a weakly negatively charged macromolecule. Low molecular weight radioactive compound(s), which was eluted in the same fractions as [(3)H]FK506, was released from [(3)H]FK506-dextran conjugate by chemical hydrolysis with a half-life of 150 h in phosphate buffer. In vitro immunosuppressive activity of the conjugate, as assessed by the rat lymphocyte stimulation test, was almost comparable to that of free FK506, suggesting that biologically active FK506 could be liberated from the conjugate. In vitro biodistribution studies demonstrated that conjugation with the dextran derivative dramatically changed the pharmacokinetic properties of FK506 after intravenous injection in rats. AUC of the FK506-dextran conjugate was almost 2000 times higher than that of free FK506 and organ uptake clearances of the conjugate were significantly smaller than those of the free drug. Thus, the present study has demonstrated that the FK506-dextran conjugate behaves as a prodrug of FK506 with an extended blood circulating time and can be expected to have an improved therapeutic potency.

Chitosan: a unique polysaccharide for drug delivery

The aim of this review is to give an insight into the many potential applications of chitosan as a pharmaceutical drug carrier. The first part of this review concerns the principal uses of chitosan as an excipient in oral formulations (particularly as a direct tableting agent) and as a vehicle for parenteral drug delivery devices. The use of chitosan to manufacture sustained-release systems deliverable by other routes (nasal, ophthalmic, transdermal, and implantable devices) is discussed in the second part.

Extravasation of macromolecules

Macromolecules can extravasate across the normal endothelium by transcapillary pinocytosis as well as by passage through interendothelial cell junctions, gaps or fenestrae. The main biological factors that control extravasation of a solute include regional differences in the capillary structures, the disease state of the organ or tissue, and the rate of blood and lymph supply. Physicochemical properties that are of profound significance in the extravasation of macromolecules are molecular size, shape, charge and hydrophilic/lipophilic balance (HLB) characteristics. Extravasation of small drugs, proteins, oligonucleotides and genes can be controlled by conjugating or forming complexes with macromolecular carriers. This requires a thorough understanding of the relationship between the chemical structures, physicochemical properties and the pharmacokinetics of both carrier and active molecules. This review article discusses the extravasation of macromolecules from the view points of pharmacokinetics and drug delivery systems, with the main emphasis on the extravasation across the liver, kidney and tumor capillaries.

Pharmacokinetic characteristics and therapeutic effects of mitomycin C-dextran conjugates after intratumoural injection

The pharmacokinetics and therapeutic effects of macromolecular prodrugs of mitomycin C (MMC), MMC-dextran conjugates (MMC-D) were studied after intratumoural injection in rats bearing Walker 256 carcinosarcoma. As the first step, the intratumoural disposition characteristics of these drugs were delineated in perfusion experiments employing a tissue-isolated tumour preparation. While MMC immediately disappeared from the tumour preparation following direct intratumoural injection, cationic and anionic MMC-D were retained in the tumour longer, demonstrating that the intratumoural clearance of MMC can be greatly retarded by dextran conjugation. The effect was more pronounced in the case of the cationic conjugate. Venous outflow data in the perfusion experiments were analyzed based on a compartment model in which the tumour tissue was assumed to consist of two compartments, one well- and the other poorly-perfused. The pharmacokinetic analysis revealed that macromolecular conjugation reduced elimination of MMC from the poorly-perfused region rather than well-perfused region. Simulation of conjugated and free MMC levels in the tissue using the calculated parameters clearly showed that intratumoural injection of MMC-D, especially the cationic form, can maintain a certain level of active free MMC in the tissue for a much longer time period. The long retention of cationic MMC-D in tumour after intratumoural injection was also confirmed by an in vivo pharmacokinetic study and whole body autoradiography in rats bearing subcutaneous Walker 256 carcinosarcoma. In addition, superior antitumour activity of cationic MMC-D was observed against subcutaneous tumours after intratumoural injection. Together with the finding that MMC is selectively toxic to hypoxic tumour cells at low concentrations, these pharmacokinetic studies strongly support the therapeutic efficacy of the macromolecular prodrugs.

Macromolecular carrier systems for targeted drug delivery: pharmacokinetic considerations on biodistribution

This review article describes the current status and future perspectives of site-specific drug delivery by means of macromolecular carrier systems. Basic aspects and recent advances of targeted delivery of 1) conventional drugs, 2) protein drugs, and 3) gene medicines including antisense oligonucleotides and plasmid DNA, are reviewed from a pharmacokinetic perspective. Successful in vivo application of macromolecular carrier systems requires pharmacokinetic considerations at whole body, organ, cellular and subcellular levels. The integration of simultaneous research progress in the multidisciplinary fields such as biochemistry, cell and molecular biology, pharmacology, and pharmacokinetics will accelerate the emergence of marketed drugs with macromolecular carrier systems.

A novel tumor-associated antigen expressed in human uterine and ovarian carcinomas

BACKGROUND

A large number of monoclonal antibodies (MoAbs) against human tumor cells have been generated and it has been shown that these MoAbs are useful tools in the diagnosis and treatment of cancer patients, as well as in the basic investigation of the oncogenesis and characterization of cancer cells.

METHODS

The 22-1-1 MoAb was established by cell fusion between mouse myeloma cells and spleen cells derived from mice immunized with the human uterine cervical adenocarcinoma cell line, SiSo. The tissue distribution and biologic characteristics of the 22-1-1 antigen (Ag) were examined.

RESULTS

The 22-1-1 Ag was distinct from the known tumor-associated antigens such as YH 206, GA 733, CA 125, carcinoembryonic antigen, and sialyl Le(x) molecules in an expression pattern in human tumor cell lines. An immunohistochemical study revealed that 22-1-1 Ag was expressed in 87.5% of uterine cervical adenocarcinomas, 66% of uterine endometrial adenocarcinomas, and 58.8% of ovarian carcinomas. Moreover, 22-1-1 Ag was detected in 87.7% of uterine cervical squamous cell carcinomas; however, it was not detected in 87.7% of uterine cervical or ovarian tissues, except in uterine endometrial glands, in which its expression was observed at low levels. The 22-1-1 Ag was secreted into cell culture supernatant fluids and was also detected in the vaginal discharges of uterine cervical carcinoma patients. The antigenic epitope of 22-1-1 Ag was shown to be a protein with a molecular weight of 78 kilodaltons using sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis.

CONCLUSIONS

The 22-1-1 MoAb reactive to a novel tumor-associated antigen was generated. This Ag was expressed in cancer cells derived mainly from the uterus and ovary. Moreover, 22-1-1 Ag was associated in the vaginal discharges of uterine cervical carcinoma patients. 22-1-1 MoAb is a potential tool for the study of oncogenesis and the management of cancer patients.

Localization and biodistribution of conjugate ATG-Dex-DNR in nude mice as models for human leukemia

131I-labelled anti-thymoglobuline (ATG), 131I-labelled immunoconjugate ATG-Dex-DNR and 131I-labelled Ts-MoAb as control antibody, respectively, were injected by intraperitoneal (i.p.) administration into nude mice used as models for human T-cell leukemia. SPECT imaging was performed from day 1 to day 8 following i.p. injection. The results showed that radioimmunoimaging of human tumor xenografts was clearest day 3 after injection in both of ATG and ATG-Dex-DNR groups, whereas it's not the case in Ts-MoAb group. Nude mice were killed 8th day after injection with antibody or conjugate. The tumor, as well as different dissected normal organs including heart, liver, lungs, kidney, femur and intestine, were harvested, weighed precisely, and radioiodine-counted. T/NT ratios in experimental group was greater than 1.0 (ranged from 1.246-7.865), and in control group they were less than 1.0 (ranged from 0.263-0.757, except for tumor/femur ratio). Our results indicated that ATG and ATG-Dex-DNR had specific affinity to cell line of T-cell leukemia CEM.

Stability and pharmacokinetic characteristics of oligonucleotides modified at terminal linkages in mice

To construct the strategy for delivery systems that can control in vivo disposition of antisense oligonucleotides, we studied the stability and basic pharmacokinetic characteristics of oligonucleotides. Decathymidylic acid (T10), a model oligodeoxynucleotide, and its derivatives, 5'-biotin-T10) and 3'-methoxyethylamine 5'-biotin-T10 (3'M5'B-T10), containing phosphoroamidate modification at 3'- and/or 5'-terminal internucleoside linkages, were synthesized. In phosphate-buffered saline (PBS, pH 7.4) containing 10% mouse serum, unmodified T10 was degraded with a half-life of 45 minutes; the degradation half-lives of 5'B-T10 and 3'M5'B-T10 were 11 and 30 h, respectively. In mouse whole blood, 3'M5'B-T10 was relatively stable, and 45% remained intact after 1 h incubation. After intravenous injection of [3H]3'M5'B-T10 into mice at a dose of 1 mg/kg, the radioactivity was rapidly cleared from plasma with a half-life of 2 minutes and accumulated in the kidney, liver, and gallbladder. About 30% of the dose was excreted in the urine within 60 minutes. A much more rapid degradation of [3H]3'M5'B-T10 was observed in vivo than expected from in vitro experiments: more than 90% of the radioactivity in plasma was degradation product at 2 minutes after injection. These results suggested that enzymatic degradation occurred in some compartments in addition to the blood pool. The apparent urinary excretion clearance of [3H]3'M5'B-T10 was close to that of inulin, whereas the apparent hepatic uptake clearance was much greater than that of inulin and comparable to that of dextran sulfate, which is taken up by the liver by scavenger receptors for polyanions.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental study on chemotherapy using adsorbent charcoal with CDDP administered directly into the mediastinum following esophagectomy

In this study, 1500AA, an activated charcoal with a strong affinity for the lymphatic system, was examined for its ability to deliver chemotherapy to metastatic lymph nodes. First, the anticancer effect on metastatic lymph nodes was assessed in an experiment using the mouse mammary tumor, MM48. Pathological examination of the inguinal lymph nodes revealed a metastatic rate of 50% in the group given cisplatin (CDDP)-saline, but 20% in the group given CDDP-charcoal. Next, in a canine model, CDDP dissolved in normal saline was administered directly into the mediastinum, and CDDP was given with fine particles of activated charcoal in the same manner in the other group. The concentration of CDDP in the lymph nodes and the plasma rapidly increased to peak in 10 min in the CDDP-saline group, whereas it increased slowly to peak in 20-30 min in the CDDP-charcoal group. Moreover, the CDDP-charcoal group was found to have a much higher concentration of CDDP in the lymph nodes than the CDDP-saline group.

Control of in vivo fate of albumin derivatives utilizing combined chemical modification

Three types of bovine serum albumin (BSA) derivatives such as lactosylated BSA (LBSA), mannosylated BSA (Man-BSA), and cationized BSA (cBSA) were synthesized and their hepatic disposition characteristics in mice were evaluated by pharmacokinetic analysis. At lower doses (< or = 1 mg/kg), LBSA and Man-BSA were very rapidly eliminated from the blood circulation due to uptake by parenchymal and nonparenchymal cells of the liver, respectively, via receptor-mediated endocytosis (Nishikawa et al., 1992; Nishida et al., 1991a, b). These uptake processes were nonlinear and the apparent hepatic uptake clearances (CLliver) were decreased at administered doses higher than 1 mg/kg, e.g. 10, 20, and 100 mg/kg. The liver accumulation of cBSA was also nonlinear, but its binding and/or uptake capacity in the liver was larger than those of LBSA and Man-BSA; i.e., CLliver decreased at doses higher than 20 mg/kg. In the next step, we modified these BSA derivatives by attaching polyethylene glycol (PEG), a modifier known to reduce the hepatic uptake and increase plasma retention, to achieve precise control of the in vivo disposition characteristics of BSA derivatives. By conjugation with PEG having a molecular weight of 10 kDa, the CLliver values of LBSA, Man-BSA, and cBSA were decreasing to one-seventh, one-fortyfifth, and one-onehundredthirtieth, respectively. However, liver accumulation of PEG modified LBSA and Man-BSA at 24 h after i.v. injection was not significantly different from unmodified BSA derivatives. These results suggest that it is possible to control the hepatic uptake of protein drugs by a combination of introduction of charge or sugar moieties and PEG conjugation.

Tumor localization and in vivo antitumor activity of the immunoconjugate composed of anti-human colon cancer monoclonal antibody and mitomycin C-dextran conjugate

The tissue distribution and in vivo antitumor activity of a novel monoclonal antibody-mitomycin C conjugate (A7-MMCD) composed of anti-human MAb A7 and MMC-dextran conjugate were investigated using tumor-bearing mice. A7-MMCD was prepared via an anionic dextran intermediate for the purpose of keeping the non-specific uptake by the reticuloendothelial system to a minimum. 111In-labeled A7-MMCD showed about a 5-times-greater accumulation in SW1116 (targeted tumor) than in S180 (non-targeted tumor) 48 h after injection, and produced a tumor-to-blood ratio which was 3 times higher in SW1116-bearing mice than in S180-bearing mice 96 h after injection. Accumulations in the liver, spleen, and kidney were also observed to some extent. Pharmacokinetic analysis revealed that A7-MMCD had nearly the same properties in the body as MMCDan (MMCD with an anionic charge), i.e., those of a negatively charged macromolecule. Both A7-MMCD and MMCDan had relatively similar tissue uptake rate indices for the liver and spleen. The tumor uptake rate index for SW1116 was about 2.5 times greater than that for S180, and the total amount of 111In-A7-MMCD accumulated in SW1116 was calculated to be approximately 5 times greater than the amount in S180. These results indicated that A7-MMCD could achieve site-specific targeting in the body. Furthermore, in the therapeutic experiment using SW1116 implanted subcutaneously, A7-MMCD suppressed tumor growth significantly, compared to free MMC and MMCDan. These results suggest that in designing an monoclonal antibody-drug conjugate via an intermediary, the physicochemical properties of intermediate macromolecules must also be taken into consideration to obtain a high degree of efficacy in vivo.