Effective antiviral therapy of two murine leukemias with an interferon-inducing synthetic carboxylate copolymer

Polymer-Based Drug-Free Therapeutics for Anticancer, Anti-Inflammatory, and Antibacterial Treatment

This paper summarizes the area of biomedicinal polymers, which serve as nanomedicines even though they do not contain any anticancer or antiinflammatory drugs. These polymer nanomedicines with unique design are in the literature highlighted as a novel class of therapeutics called "drug-free macromolecular therapeutics." Their therapeutic efficacy is based on the tailored multiple presentations of biologically active vectors, i.e., peptides, oligopeptides, or oligosaccharides. Thus, they enable, for example, to directly induce the apoptosis of malignant cells by the crosslinking of surface slowly internalizing receptors, or to deplete the efficacy of tumor-associated proteins. The precise biorecognition of natural binding motifs by multiple vectors on the polymer construct remains the crucial part in the designing of these drug-free nanomedicines. Here, the rationales, designs, synthetic approaches, and therapeutic potential of drug-free macromolecular therapeutics consisting of various active vectors are described in detail. Recent developments and achievements for namely B-cell lymphoma treatment, Gal-3-positive tumors, inflammative liver injury, and bacterial treatment are reviewed and highlighted. Finally, a possible future prospect within this highly exciting new field of nanomedicine research is presented.

Physical and biological properties of cyclopolymers related to DIVEMA ("pyran copolymer")

A series of copolymers related in structure to the 1:2 alternating cyclocopolymer of divinyl ether and maleic anhydride (DIVEMA) have been shown to possess antitumor properties. The synthesis and structures of these copolymers are discussed, and their effectiveness as antitumor agents is presented. Certain of the copolymers have been prepared in controlled molecular weight ranges using chain transfer agents, and the resultant copolymers finally fractionated via use of solvent-nonsolvent systems. These samples of narrow molecular weight distribution have been evaluated for their antitumor properties and have been found to be quite effective.

Suppression of Friend leukemia virus by Bacillus Calmette-Guérin and a streptococcal preparation, OK-432

OK-432, a streptococcal preparation, and BCG effectively inhibited splenomegaly in Friend leukemia virus (FLV)-infected mice. Divided drug dosage resulted in stronger inhibition than single administration. When the second dose was fixed at the 3rd pre-infection day, the best timing for the first dose was approximately 30 days before infection. The optimal dosages were 100--600 KE/kg for OK-432 and 25--100 mg/kg for BCG. Transfer of peritoneal exudate cells (PEC) from immunomodulator-treated mice, but not PEC from untreated mice, conferred resistance against FLV which was highest when PEC were transferred 1 day before FLV infection. The transfer of PEC on the day of or one day after infection had no protective effect. Inactivation also occurred when FLV was incubated in the presence of PEC from immunomodulator-treated mice, however, no significant effect was observed for PEC from untreated mice.

Inhibition of RNA-dependent DNA polymerase of avian myeloblastosis virus by pyran copolymer

PYRAN COPOLYMER, A KNOWN IMMUNOSTIMULATOR, WAS FOUND TO BE A POTENT INHIBITOR OF PURIFIED DNA POLYMERASE (DEOXYNUCLEOSIDETRIPHOSPHATE: DNA deoxynucleotidyltransferase; EC 2.7.7.7) isolated from avian myeloblastosis virus. Unlike other inhibitors, pyran showed unique features of inhibition. It interacts with the polymerase at a region other than the template site. The inhibitory effect was overcome only by excess enzyme and not affected by excess template. The degree of inhibition was not template specific for the templates tested: 70S RNA from avian myeloblastosis virus, synthetic hybrid poly(rA).oligo(dT)(10), synthetic copolymer poly(dA-dT), and activated calf-thymus DNA. The observed rate of inhibition by pyran was shown to vary with the different polymerases tested. Inhibition was shown with all oncornaviral polymerases and, to a lesser extent, with mammalian polymerases. However, two of the three bacterial polymerases, by contrast, showed a marked activation.

The role of interferon in the protective effect of a synthetic double-stranded polyribonucleotide against intranasal vesicular stomatitis virus challenge in mice

Intravenous injection of polyinosinic acid/polycytidylic acid [(poly rI).(poly rC)] offered significant protection against intranasal challenge of young mice with vesicular stomatitis virus (VSV). Optimal protection was obtained when a single dose was administered 2 hr before virus challenge, but repeated doses were effective when started as late as 3 days after virus challenge. The therapeutic ratio or ratio of maximum tolerated dose to minimum effective dose for a single intravenous injection of (poly rI).(poly rC) 2 hr before virus inoculation was >/=8 mg/kg:0.004 mg/kg or >/=200.Dose-response curves for interferon production and antiviral protection by (poly rI).(poly rC) were closely parallel. Equivalent doses of poly rI or poly rC alone did not exert any interferon-inducing capacity or protective effect on intranasal VSV challenge. Several factors, which are known to potentiate or antagonize interferon production, increased or decreased the interferon-inducing capacity and antiviral protection of either (poly rI).(poly rC) or maleic acid/divinyl ether copolymer (MA/DVE) in parallel. Interferon production and antiviral protection by MA/DVE were enhanced by arginine but abolished by prior treatment with MA/DVE; DEAE-dextran (intraperitoneally), kinetin riboside and isopentenyladenosine, and prior injection of endotoxin reduced both interferon production and antiviral protection by (poly rI).(poly rC). Treatment with exogenous interferon in amounts which closely mimicked the levels of circulating interferon produced endogenously by an effective dose of (poly rI).(poly rC) gave protection against intranasal VSV which was identical with that dose of (poly rI).(poly rC). This strongly suggests that interferon production accounts for the whole protective effect of (poly rI).(poly rC) in the intranasal VSV assay.

Enhancement by poly-D-lysine of poly I: C-induced interferon production in mice

Poly-d-lysine of high molecular weight enhances interferon induction in mice by the double-stranded complex of polyinosinic and polycytidylic acids and is superior to diethylaminoethyl-dextran in this respect.