Antibody-targeted polymer-bound drugs (original) (raw)
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International Journal of Cancer, 2011
Interleukin (IL)-2 has been approved for treatment of metastatic renal cancer and malignant melanoma. However, its unfavorable pharmacologic properties, severe side effects and the negative role of IL-2 in maintaining T regulatory cells are severe drawbacks. It has been shown that immunocomplexes of IL-2 and certain anti-IL-2 mAbs possess selective and high stimulatory activity in vivo. Here, we show that IL-2/S4B6 mAb immunocomplexes expand not only CD122 high subsets and newly activated CD8 1 T cells but also natural killer T cells and cd T cells. Further, we demonstrate that natural killer (NK) cells expanded by IL-2/S4B6 mAb immunocomplexes in vivo have high cytolytic activity, which can be further increased by coadministration of IL-12. We also demonstrate that IL-2/S4B6 mAb immunocomplexes possess noticeable antitumor activity in two syngeneic mouse tumor models, namely BCL1 leukemia and B16F10 melanoma, but only if administered early in tumor progression. To effectively treat established tumors, we administered the tumor-bearing mice first with N-(2hydroxypropyl)methacrylamide copolymer-bound doxorubicin conjugate, and subsequently with IL-2/S4B6 mAb immunocomplexes alone or with IL-12 to induce an efficient antitumor immune response. Importantly, we show that the conjugate has significantly lower immunosuppressive activity than free doxorubicin when using dosage with comparable antitumor activity, thus eliminating the majority of tumor cells while leaving the immune system mostly unimpaired for stimulation with IL-2/S4B6 mAb immunocomplexes. Indeed, we demonstrate that the conjugate and IL-2/S4B6 mAb immunocomplexes together have synergistic antitumor activity.
Journal of Drug Targeting, 2013
Introduction: Fine needle aspiration biopsy (FNAB) is an easy method with an option of repetitive withdrawal of cell material. Methods: First, mice were inoculated with mouse T-lymphoma, after 10 d the samples from tumor, lymph nodes and spleen gained by FNAB and excision were analyzed by flow cytometry. Tumor progression was compared to the control group simultaneously. Then, 10 d after tumor cell inoculation free doxorubicin (DOX) or different PHPMA DOX conjugates were injected. Cell material was analyzed to detect subpopulations of lymphocyte infiltrate, and levels of cytokines in correlation with progression or regression of the disease. Results: FNAB has no influence on the tumor's growth or survival of experimental animals. After treatment with PHPMA conjugates there was a significant increase of T-lymphocyte subpopulations in tumor microenvironment compared to controls or free DOX, but only in mice with confirmed macroscopic regression of tumor within two weeks. Mice treated with conjugates showed significantly lower cancer infiltration of lymph nodes and spleen. Conclusion: FNAB provides a great benefit to in vivo monitoring of cell changes directly in the tumor after treatment. The number of infiltrating T-lymphocytes increases in correlation with consecutive tumor eradication after treatment with PHPMA. This proves that not only direct cytotoxic but also imunostimulating effect are necessary for successful treatment.
Induction of Systemic Antitumour Resistance with Targeted Polymers
Scandinavian Journal of Immunology, 2005
Conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA) represent a new generation of antibody-targeted polymeric anticancer drugs with both cytotoxic and immunoprotecting/immunomobilizing activity. 20-90% of mice that are cured of EL4 mouse T-cell lymphoma, BCL1 mouse B-cell leukaemia and 38C13 mouse B-cell lymphoma by injection of doxorubicin-HPMA conjugate develop a long-lasting memory and systemic antitumour resistance. It is suggested that the main activity of the polymeric drug, directly after application is -due to the high level of the drug -of cytotoxic and cytostatic nature. Thereafter, long-term conjugates persist at low concentration in the circulation, which are capable of mobilizing the defence mechanisms of the host. Until now, seven patients with generalized carcinoma were treated with doxorubicin-HPMA-human-Ig conjugate. Disease stabilization, lasting from 6 to more than 18 months, was recorded.
Cancer Immunology, Immunotherapy, 2006
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 antitumour 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 naı¨ve 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.
Journal of Immunotherapy, 2008
Tumors are considered to be possible targets of immunotherapy using stimulated and expanded cytotoxic Tlymphocytes (CTL). It is important to consider the drug-induced effects when chemotherapeutic regimens and CTL-mediated immunotherapy is planned to be used in parallel. In this study, we characterized the effect of 29 frequently used chemotherapeutic agents on the cytotoxic activity of autologous and allogeneic CTLs. We found that treatment of CTLs with the following drugs: docetaxel, vincristine, chlorambucil, mitomycin C, oxaliplatin, doxorubicin, and bleomycin effectively inhibited CTL-mediated killing, without affecting their viability. On the other hand, the following drugs enhanced or permitted efficient CTL-mediated killing in vitro at concentrations comparable with the maximally achieved therapeutic concentration in vivo in humans: daunorubicin, prednisolone, vinorelbine, cisplatin, methotrexate, hydroxyurea, cytarabine, cyclophosphamide, topotecan, epirubicin, fluorouracil, carboplatin, asparaginase, 6-mercaptopurine, and bortezomib. Our results could poten-tially be used in the future to design new CTL-based adjuvant immunotherapy protocols. Financial Disclosure: The authors have declared there are no financial conflicts of interest related to this work. Henriette Skribek and Michael Uhlin contributed equally to this work. Authors' contributions: The project was conceived and designed by Laszlo Szekely and Gyorgy Stuber. The experiments were mainly carried out and/or coordinated by Laszlo Markasz. Michael Uhlin created and cultures all CTL lines and LCLs used in the experiments. Gyorgy Stuber, Laszlo Markasz, and Rita Otvos took part in preparation of the microtiter plates for in vitro drug sensitivity assays. Laszlo Markasz and Rita Otvos were responsible for measuring the plates using the automated laser confocal fluorescent microscope. Laszlo Szekely and Emilie Flaberg wrote the computer programs QuantCapture 4.0 and CytotoxCount 3.0. Laszlo Markasz and Henriette Skribek analyzed and interpreted the data. Staffan Eksborg made comparable the in vitro results with the in vivo data. Eva Olah, Henriette Skribek together with the other authors have been involved in the planning of the experimental details, and the drafting, and critical reading of the manuscript. All authors read and approved the final manuscript. Reprints: Laszlo Szekely,
Journal of Immunotherapy, 2004
Purpose: Although Rituximab has produced significant tumor regressions in lymphoma patients, only 50% respond. Clinically, it has been shown that the major mechanism of action of Rituximab is antibody-dependent cytotoxicity requiring presentation by Fc-bearing cells. To improve the clinical efficacy of Rituximab for the treatment of CD20 + lymphomas, we now describe a new formulation of Rituximab, which, on direct binding to target, can induce apoptosis. Methods: In this report, enhanced apoptosis was observed by treating CD20 + lymphoma cells with a new polymer formulation of Rituximab. The polymer was produced by formation of a peptide bond using the sugar moiety of dextran (MW 6,000) to generate a clinically relevant reagent for use in vivo. Results: Comparison of Rituximab with a previously described dimer and the newly generated polymer shows that the polymer induced apoptosis more effectively in CD20 + cells as shown by the terminal deoxyribonucleotidyl transferase^mediated dUTP nick end labeling assay (Rituximab, 3%; dimer, 3%; polymer, 58%). Consistent with these results, the polymer produced marked regression in CD20 + lymphoma xenografts, whereas the dimer and monomer reagents showed little effect. In addition, we were able to show that the level of apoptosis induced in human lymphoma cell lines was in accordance with the extent of both surface CD20 clustering and caspase-3 activation. Conclusions:These data suggest that hyper-cross-linking^induced apoptosis can be simulated by the use of a dextran polymer of Rituximab, which, when used in vivo, can directly kill CD20 + lymphoma cells and improve the clinical efficacy of this important therapeutic for human B-cell lymphomas.
Superiority of an Acid-labile Daunorubicin-Monoclonal Antibody Immunoconjugate Compared to Free Drug
Cancer Research, 1988
We conjugated the chemotherapy agent daunorubicin to the anti-Tcell monoclonal antibody T101 using an active ester intermediate of the acid-labile linker m-aconitate anhydride. By converting carbohydrate hydroxyl groups on the antibody to amines prior to conjugation, average drug to antibody ratios of 25:1 »ereachieved with retention of cytotoxicity and only minimal loss of immunoreactivity. The pH sensitivity of the linkage was confirmed. The preparation was cytotoxic for antigen-bearing cells but not antigen-negative cells, even up to 48-h incubation in vitro. Specific cytotoxicity was apparently mediated through the endocytosis of the intact 1101 immunoconjugate and the release of the active drug in the lysosomal compartment. Athymic mice bearing human tumor xenografts who received a single injection of the ¡mmunoconjugatehad less tumor growth and more tumor regressions than animals receiving anti body alone, drug alone, or a mixture of drug plus antibody. This approach appears promising for further investigation.
Cancer research, 1991
Many of the experimental approaches used in the search for new targeted drug delivery systems ignore the disseminated nature of metastatic disease; the development of more relevant tumor models is therefore a priority. A reproducible and tumor-specific model has been generated by inoculating (C57BL/6 x BALB/c) F1 (Ly-2.2+) mice i.v. with the Ly-2.1+ murine ITT(1) 75NS E3 thymic lymphoma (E3). At a dose of 2 x 10(6) cells, E3 tumors grew in a disseminated fashion, arising initially and predominantly in the lung and kidney, and later and less often in the thymus, spleen, and other tissues. In addition, histopathological examination and flow cytometry of blood did not detect E3 tumor cells in most other organs or in the circulation throughout the course of disease. The mean survival time (MST) of untreated mice was both reproducible and proportional to the number of E3 tumor cells injected and was therefore used to demonstrate the suitability of this model for immunochemotherapeutic st...
In vitro cytotoxic study of immunoliposomal doxorubicin targeted to human CD34+ leukemic cells
Life Sciences, 2004
The expression of CD34 antigen in acute myelogenous leukemias is considered an unfavourable prognosis marker for response to anticancer drugs and duration of remission. This study investigated the applicability of long-circulating immunoliposomes loaded with doxorubicin targeted to CD34 antigen present on MDR+ human myelogenous leukemia KG-1a cell line. Immunoliposomal doxorubicin showed a higher cytotoxicity against KG-1a cells than non-targeted liposomal doxorubicin, but it did not improve over that of free drug. Although no reversal of doxorubicin resistance was found to occur through its liposomal encapsulation, a therapeutic benefit can be obtained by the selective cytotoxicity observed. Endocytosis studies demonstrated that, after binding to CD34 antigen, the immunoliposomes are not internalized by the KG-1a cells and so the cytotoxic effect might be due to drug released into the space near the cell membrane. Thus, immunotargeting of liposomal doxorubicin to CD34+ leukemic cells may only provide an ex vivo strategy for site-selective CD34+ leukemia cell killing.