PURPOSE: In vivo efficacy and safety of HPMA-based copolymers armed with doxorubicin via a spacer containing pH-sensitive linkage that can be prepared within a broad range of attached drug contents (1) was tested in murine tumor models. METHODS: Mice bearing T cell lymphoma EL4 or B cell lymphoma 38C13 were treated with a single dose of the conjugate (15, 25, and 75 mg Dox eq./kg i.v.) in a therapeutic regime. Anti-tumor resistance of the cured animals was proved by a second challenge with a lethal dose of tumor cells without additional treatment. RESULTS: The content of drug bound to the polymer is an important parameter in relation to the conjugate therapeutic efficacy. The best anti-tumor effects were produced by conjugates with 10 - 13 wt% of bound doxorubicin. Free doxorubicin up to 4.6% relative to total drug content had no impact on the treatment efficacy and acute toxicity. The conjugates induced a complete cure of mice and regular treatment-dependent development of specific anti-tumor resistance. No myelosuppression or organ damage was observed. CONCLUSIONS: A well-defined HPMA copolymer-doxorubicin conjugate with pH-sensitive drug release is a good candidate for clinical trials as it has remarkable anti-tumor efficacy and a favorable safety profile.

• MeSH
• Doxorubicin analogs & derivatives   chemical synthesis   pharmacokinetics   pharmacology   MeSH
• Immunomodulation drug effects   MeSH
• Hydrogen-Ion Concentration MeSH
• Polymethacrylic Acids chemical synthesis   pharmacokinetics   pharmacology   MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Drug Carriers chemical synthesis   pharmacokinetics   pharmacology   MeSH
• Polymers * chemical synthesis   pharmacokinetics   pharmacology   MeSH
• Cell Proliferation drug effects   MeSH
• Antibiotics, Antineoplastic pharmacokinetics   pharmacology   MeSH
• Xenograft Model Antitumor Assays MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• doxorubicin-N-(2-hydroxypropyl)methacrylamide copolymer conjugate MeSH Browser
• Doxorubicin MeSH
• Polymethacrylic Acids MeSH
• Drug Carriers MeSH
• Polymers * MeSH
• Antibiotics, Antineoplastic MeSH

Linkage of doxorubicin (Dox) to a water-soluble synthetic N-(2-hydroxypropyl)methacrylamide copolymer (PHPMA) eliminates most of the systemic toxicity of the free drug. In EL-4 lymphoma-bearing C57BL/6 mice, a complete regression of pre-established tumours has been achieved upon treatment with Dox-PHPMA-HuIg conjugate. The treatment was effective using a range of regimens and dosages, ranging from 62.5 to 100% cured mice treated with a single dose of 10-20 mg of Dox eq./kg, respectively. Fractionated dosages producing lower levels of the conjugate for a prolonged time period had substantial curative capacity as well. The cured mice developed anti-tumour protection as they rejected subsequently re-transplanted original tumour. The proportion of tumour-protected mice inversely reflected the effectiveness of the primary treatment. The treatment protocol leading to 50% of cured mice produced only protected mice, while no mice treated with early treatment regimen (i.e. starting on day 1 after tumour transplantation) rejected the re-transplanted tumour. Exposure of the host to the cancer cells was a prerequisite for developing protection. The anti-tumour memory was long lasting and specific against the original tumour, as the cured mice did not reject another syngeneic tumour, melanoma B16-F10. The immunity was transferable to naïve recipients in in vivo neutralization assay by spleen cells or CD8(+) lymphocytes derived from cured animals. We propose an effective treatment strategy which eradicates tumours without harming the protective immune anti-cancer responses.

• MeSH
• Doxorubicin analogs & derivatives   therapeutic use   MeSH
• Immunoglobulins therapeutic use   MeSH
• Immune Tolerance * MeSH
• Polymethacrylic Acids therapeutic use   MeSH
• Humans MeSH
• Lymphoma, T-Cell drug therapy   immunology   prevention & control   MeSH
• Melanoma, Experimental drug therapy   immunology   metabolism   MeSH
• Survival Rate MeSH
• Mice, Inbred C57BL MeSH
• Mice, Nude MeSH
• Mice MeSH
• Tumor Cells, Cultured transplantation   MeSH
• Skin Neoplasms drug therapy   immunology   metabolism   MeSH
• Drug Carriers MeSH
• Antibiotics, Antineoplastic therapeutic use   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• doxorubicin-N-(2-hydroxypropyl)methacrylamide copolymer conjugate MeSH Browser
• Doxorubicin MeSH
• Immunoglobulins MeSH
• Polymethacrylic Acids MeSH
• Drug Carriers MeSH
• Antibiotics, Antineoplastic MeSH

PURPOSE: Two different monoclonal antibody-targeted HPMA copolymer-doxorubicin conjugates, classic and starlike, were synthesized to be used for site-specific cancer therapy. The anti-mouse Thy-1.2 (IgG3) and two anti-human CD71/A (IgG1) and CD71/B (IgG2a) monoclonal antibodies were used as targeting structures. METHODS: Their binding and cytotoxic activity in vitro, body distribution, and anticancer activity in vivo were evaluated. RESULTS: The results of flow cytometric analysis showed comparable binding of classic and starlike conjugates to the target cells. The in vitro cytotoxic effect was 10-fold higher if cancer cells were exposed to the starlike conjugate compared to the classic one. Biodistribution studies showed that the starlike conjugate remained in a relatively high concentration in blood, whereas the classic conjugate was found in a 6.5-times lower amount. In contrast to the low antitumor activity of free doxorubicin and nontargeted HPMA copolymer-doxorubicin conjugate, both anti-Thy-1.2 targeted conjugates (classic and starlike) cured all mice bearing T-cell lymphoma EL4. On the other hand, starlike conjugates containing anti-CD71/A or anti-CD71/B monoclonals as targeting structures were more effective against human colorectal cancer SW 620 than the classic one. CONCLUSIONS: We have shown that the starlike conjugates are more effective systems for targeted drug delivery and cancer treatment than classic conjugates.

• MeSH
• Cell Division drug effects   MeSH
• Doxorubicin chemistry   pharmacokinetics   pharmacology   MeSH
• Colorectal Neoplasms drug therapy   MeSH
• Humans MeSH
• Lymphoma, T-Cell drug therapy   MeSH
• Methacrylates chemistry   pharmacology   MeSH
• Molecular Structure MeSH
• Antibodies, Monoclonal chemistry   metabolism   MeSH
• Mice, Inbred BALB C MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Prodrugs chemistry   pharmacology   MeSH
• Antibiotics, Antineoplastic chemistry   pharmacokinetics   pharmacology   MeSH
• In Vitro Techniques MeSH
• Tissue Distribution MeSH
• Neoplasm Transplantation MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Doxorubicin MeSH
• hydroxypropyl methacrylate MeSH Browser
• Methacrylates MeSH
• Antibodies, Monoclonal MeSH
• Prodrugs MeSH
• Antibiotics, Antineoplastic MeSH