HPMA copolymer

Wu K, Yang JY, Konak C et al (2008) Novel synthesis of hpma copolymers containing peptide grafts and their self-assembly into hybrid hydrogels. Macromol Chem Phys 209 467 75... 

Yang JY, Xu CY, Kopeckova P et al (2006) Hybrid hydrogels self-assembled from hpma copolymers containing peptide grafts. Macromol Biosci 6 201-209... 

David, A., Kopeckova, P., Rubinstein, A., Kopecek, J., Enhanced biorecognition and internalization of HPMA copolymers containing multiple or multivalent carbohydrate side-chains by human hepatocarcinoma cells. Bioconjug Chem 12, 890-... 

Matthews, N., Neale, M.L., Jackson, S.K., and Stark, J.M., 1987, Tumor cell kilhng by tumor necrosis factor inhibition by anearobiotic condition, free-radical scavengers and inhibitors of arachidonate metabolism. Immunology 62 153-155 Miller, M.G., Rodgers, A., and Cohen, G.M., 1986, Mechanisms oftoxicity of naphthoquinones to isolated hepatocytes. Biochem. Pharmacol. 35 1177-1184 Minko, T., Kopeckova, P., and Kopecek, J., 1999, Comparison ofthe anticancer effect of free and HPMA copolymer-bound adtiamycin in human ovarian carcinoma cells. Pharmaceut. Res. 16 986-996... 

HPMA copolymers are water-soluble biocompatible polymers, widely used in anticancer drug delivery (reviewed in Reference [22]). HPMA copolymers containing reactive groups at side-chain termini were previously used for the modification of trypsin [23], chymotrypsin [23,24], and acetylcholinesterase [25]. The modification dramatically increased the acetylcholinesterase survival in the blood stream of mice and the thermostability of modified enzymes when compared to the native proteins. However, the modification involved multipoint attachment of the copolymers to the substrates, which may cause crosslinking. To modify proteins or biomedical surfaces by one point attachment, semitelechelic polymers should be used. 

As the first step, a Ni(II) metal complex of HPMA copolymer was formed and purified [35]. It was then mixed with protein solutions to form dried films, which were rehydrated to investigate the swelling profile and stimuli sensitivity. 

For cancer therapy, the well estabhshed N(-2-hydroxypropyl)methacrylamide (HMPA) polymers have been extensively studied. PKl, a 28-kDa HPMA copolymer containing doxorubicin (Figure 1.3) is now in clinical testing [15]. Other drugs that have been incorporated... 

Figure 1.3. Structure of PKl (HPMA copolymer doxorubicin), a 28-kDa polymeric carrier-drug conjugate investigated for its anti-tumour activity in a phase I clinical study. Adapted from reference [15].

Examples of HPMA Copolymer-Anticancer Drug Conjugates.. 105... 

HPMA copolymer Adriamycin Amide bond between drug aminoribosyl and oligopeptide spacer carboxyl Galactosamine... 

HPMA copolymer Melphalan Amide bond between drug amine and variable oligopeptide spacer carboxyl None... 

HPMA copolymer Chlorin e6 Amide bond between drug carboxyl and spacer amine anti-Thy 1.2 antibody... 

Synthesis of an adriamycin-HPMA copolymer-galactosamine conjugate is shown in Fig. 10. Attachment/release points at the side-chain termini are created by incorporation of tailor-made comonomers into the copolymer structure. 

Fig. 10a. Structure of a targetable polymeric drug based on HPMA copolymer carrier.

Cultures consisting of cell suspensions may be used directly to determine the efficacy of macromolecular antitumor agents. For example, suspensions of L12 10 leukemia cells were used to show the activity of HPMA copolymer anticancer drug conjugates [39], The cells, while in exponential growth, were diluted in culture medium to produce a cell density of approximately... 

B16 melanoma, Walker sarcoma, and M5076 forming liver metastasis have been used in the preclinical evaluation of HPMA copolymer-adriamydn conjugates [36]. Other tumors useful for secondary screening are MS-2 sarcoma, NMU-1 murine lung adenocarcinoma, and murine adenocarcinoma Colon 26. These have been used by Zunino et al. [147] to determine the activity of poly (carboxylic acid) immobilized anthracyclines. Mice inoculated intramuscularly with Lewis lung carcinoma have been used by Pratesi et al. [215] to assess the effect of a poly-L-aspartic acid/doxorubicin conjugate. 

The above mentioned effects were observed with different inert polymeric carriers. The results obtained with HPMA copolymer-drug conjugates are discussed in Sect. 5.3., the decrease of the immunogenicity of proteins after PEG modification in Sec. 2.1.1.1. 

The relationship between the structure of the oligopeptide sequences and the rate of enzymatically catalyzed release of a drug or drug model was studied in detail. Over 50 different oligopeptide sequences were introduced into HPMA copolymers and their degradability by different enzymes studied. First, model enzymes, chymotrypsin [235, 238,239, 243,244], trypsin [245], and papain... 

The stability of the oligopeptide side-chains in blood plasma and serum was determined [251]. Based on these results it was possible to control the degradability of HPMA copolymers by a particular enzyme as well as in the in vivo system [169, 252]. 

The influence of the structure of the main chain on the chymotrypsin catalyzed release of p-nitroaniline is shown in Fig. 15. Oligopeptide p-nitroanili-des were attached to HPMA copolymers (as side-chains) and to polyethylene glycol (end-point attachment). From the values of kcat/KM it is evident that all oligopeptide p-nitroanilides attached to PEG were cleaved faster than those attached to HPMA copolymers. It appeared that the PEG substrates fit better into the active site of chymotrypsin due to the linearity and flexibility of the PEG molecule, and the type of spacer attachments [255]. 

Fig. 14. Initial interval of cleavage of HPMA copolymer based polymeric substrates by lysosomal cysteine proteinase cathepsin B (isolated from bovine spleen). Only the cleavage of the bond between the distal amino acid residue and p-nitroaniline was monitored. Conditions of cleavage [Cathepsin B] = 1.9 x 10 7 M [NAp] = 1.2 x 1(T3 M [EDTA] = 1 x 10 3 M [Cys] = 2.5 x 10 2 M 0.1 M phosphate buffer pH = 6.0 40 °C. Data from [249]...

This receptor recognizes galactose and Af-acetylgalactosamine moieties [259], To determine if a synthetic macromolecule containing one of these units would be biorecognizable in vivo, we synthesized HPMA copolymers with N-methacryloylglycylglycine p-nitrophenyl ester and attached galactosamine by... 

Fig. 18. Structure and blood clearance of synthetic HPMA copolymers mimicking the structure of glycoproteins and asialoglycoproteins. Based on data from [261]...

Fig. 19. Body distribution of adriamycin-HPMA copolymer conjugates 1 h after intravenous administration to rats. The distribution of a targetable conjugate containing the galactosamine moiety is compared with a conjugate without targeting moiety. Based on data from [264]...

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