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 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent progress in the development of molecular cancer therapeutics has revealed new types of antitumor drugs, such as Herceptin, Gleevec, and Iressa, as potent therapeutics for specific tumors. Our work has focused on molecular cancer therapeutics, mainly in the areas of drug resistance, apoptosis and apoptosis resistance, and survival-signaling, which is related to drug resistance. In this review, we describe our research on molecular cancer therapeutics, including molecular mechanisms and therapeutic approaches. Resistance to chemotherapeutic drugs is a principal problem in the treatment of cancer. P-Glycoprotein (P-gp), encoded by the MDR1 gene, is a multidrug transporter and has a major role in multidrug resistance (MDR). Targeting of P-gp by small-molecular compounds and/or antibodies is an effective strategy to overcome MDR in cancer, especially hematologic malignancies. Several P-gp inhibitors have been developed and are currently under clinical phased studies. In addition to the multidrug transporter proteins, cancer cells have several drug resistance mechanisms. Solid tumors are often placed under stress conditions, such as glucose starvation and hypoxia. These conditions result in topo II poison resistance that is due to proteasome-mediated degradation of DNA topoisomerases. Proteasome inhibitors effectively prevent this stress-induced drug resistance. Glyoxalase I, which is often elevated in drug- and apoptosis-resistant cancers, offers another possibility for overcoming drug resistance. It plays a role in detoxification of methylglioxal, a side product of glycolysis, which is highly reactive with DNA and proteins. Inhibitors of glyoxalase I selectively kill drug-resistant tumors that express glyoxalase I. Finally, the susceptibility of tumor cells to apoptosis induced by antitumor drugs appears to depend on the balance between pro-apoptotic and survival (anti-apoptotic) signals. PI3K-Akt is an important survival signal pathway, that has been shown to be the target of various antitumor drugs, including UCN-01 and geldanamycin, new anticancer drugs under clinical evaluation. Our present studies provide novel targets for future effective molecular cancer therapeutics.
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PMID:Molecular targeting therapy of cancer: drug resistance, apoptosis and survival signal. 1270 68

Targeting drugs for delivery and release has the potential to increase the efficacy of treatment. A bifunctional linker, A-Z-CINN Linker was used to create a targeted prodrug, A-Z-CINN 310. A-Z-CINN Linker links to a potent chemotherapeutic agent, paclitaxel, via an energy-reversible ester bond and also binds a targeting agent, the monoclonal antibody trastuzumab (Herceptin). This study demonstrates the effectiveness of a single-treatment use of A-Z-CINN 310 in decreasing tumor volume and tumor cell density of human HER-2-positive BT-474 mammary tumor cells implanted in scid mice, compared to treatment with simultaneously administered trastuzumab and paclitaxel and with saline control. After treatment with A-Z-CINN 310, some mice received light exposure at 6 h for 5 min adjacent to the tumor to cause light-accelerated release of paclitaxel. Changes in tumor volume were measured for 28 days following treatment; changes in histology were measured at 31 days. Animals treated with A-Z-CINN 310, then light, showed dose-dependent decreases in tumor volume and tumor cell density which were more rapid and extensive than those seen with A-Z-CINN 310 without light or a 10-fold higher concentration of co-administered trastuzumab plus paclitaxel. This suggests that targeted delivery of paclitaxel using A-Z-CINN 310 kills tumor cells by localized release of paclitaxel at the tumor site, which can be accelerated by light treatment. These results indicate that a targeted prodrug therapy containing trastuzumab as the targeting agent and A-Z-CINN-paclitaxel as the prodrug results in a conjugate that is more effective in killing tumor cells than equivalent concentrations of co-administered trastuzumab and paclitaxel. Targeting of a drug can reduce the dose needed for effective therapy and can increase local bioavailability. This makes targeted therapy using an A-Z-CINN prodrug delivery system feasible for treating both primary and metastatic tumors.
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PMID:Targeted prodrug treatment of HER-2-positive breast tumor cells using trastuzumab and paclitaxel linked by A-Z-CINN Linker. 1272 56

The amplification and/or overexpression of the HER-2/neu oncogene and its encoded receptor protein are increasingly used for prognostication and prediction of therapeutic response to Herceptin in breast cancer. However, large-scale examination of archival tumor blocks by immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) is prohibitively laborious and technically challenging. The tissue microarray (TMA) technique enables hundreds of tumors to be studied simultaneously in a single experiment. To evaluate the HER-2/neu status of a selection of the breast tumors in our tumor bank, we constructed a TMA from 97 breast tumors, with a single 0.6-mm core per specimen. HER-2/neu gene amplification by FISH was found in 20 of the 87 interpretable cases (23%): in 14 of 14 IHC 3+ cases (100%), 5 of 8 IHC 2+ cases (62.5%) and 1 of 65 IHC 0/1+ cases (1.5%). Three of the 67 cases with no evidence of HER-2/neu gene amplification by FISH were moderately positive (2+) by IHC. A close relationship was observed between these 2 assays as applied to the TMA (95.4% concordance: 95% CI, -2.2% to 6.8%; P <0.0001), and both HER-2/neu gene amplification and protein overexpression were strongly associated with tumor grade, estrogen receptor status, and progesterone receptor status. Gene amplification was found in most of the tumors with high-level overexpression (IHC 3+) and not in the unequivocal IHC-negative cases. Complementary analysis by IHC and FISH are, however, recommended for tumors graded as 2+ by IHC, the group with the most result discrepancy. Hum Pathol 34:362-368.
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PMID:Evaluation of HER-2/neu oncogene status in breast tumors on tissue microarrays. 1273 17

In breast cancer, about 35% of patients without any clinical signs of overt distant metastases already have disseminated tumor cells in bone marrow aspirates at the time of primary therapy. A significant prognostic impact of these disseminated tumor cells has been shown by many international studies: patients with tumor cells in their bone marrow have a significantly worse prognosis than those without them. Even in malignancies where the skeletal system is not a preferred location for distant metastasis, such as ovarian cancer, early presence of minimal residual disease (MRD) is correlated with poor patient outcome. Thus, besides analysis of the primary tumor, detection of MRD can be used for assessment of patient prognosis and for prediction or monitoring of response to systemic therapy. Disseminated tumor cells are also the targets for novel tumor biological therapy approaches such as specific antibody-based therapies against target cell-surface antigens such as HER2, Ep-CAM (17-1A), and uPA-R. In breast cancer, a first antibody-based tumor therapy against HER2 (Herceptin) has already been approved for clinical use in recurrent disease. However, patient selection for such tumor biological therapies becomes rather difficult due to phenotype changes, which may manifest themselves as differences between primary lesion and disseminated tumor cells. Therefore, not only identification of disseminated tumor cells but even more so their characterization at the protein and gene levels have become increasingly important. In conclusion, characterization of tumor biological properties of disseminated tumor cells allows identification of patients with breast cancer or gynecological malignancies at risk for relapse who are likely to benefit from systemic treatment and/or novel tumor biological therapy approaches.
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PMID:Minimal residual disease in breast cancer and gynecological malignancies: phenotype and clinical relevance. 1279 Mar 24

Estrogen receptor (ER)-positive breast cancers generally have a better prognosis and are often responsive to anti-estrogen therapy, which is the first example of a successful therapy targeted on a specific protein, the ER. Unfortunately ER-negative breast cancers are more aggressive and unresponsive to anti-estrogens. Other targeted therapies are thus urgently needed, based on breast cancer oncogene inhibition or suppressor gene activation as far as molecular studies have demonstrated the alteration of expression, or structure of these genes in human breast cancer. Using the MDA-MB.231 human breast cancer cell line as a model of ER-negative breast cancers, we are investigating two of these approaches in our laboratory. Our first approach was to transfect the ER or various ER-deleted variants into an ER-negative cell line in an attempt to recover anti-estrogen responsiveness. The unliganded receptor, and surprisingly estradiol, were both found to inhibit tumor growth and invasiveness in vitro and in vivo. The mechanisms of these inhibitions in ER-negative cancer cells are being studied, in an attempt to target the ER sequence responsible for such inhibition in these cancer cells. Another strategy is trying to inhibit the activity or expression of an oncogene specifically overexpressed in most breast cancers. This approach was recently shown by others to be efficient in breast cancer therapy with HER2-Neu oncogene amplification using Herceptin. Without excluding other molecular putative targets, we have focused our research on cathepsin D as a potential target, since it is often overexpressed in aggressive human breast cancers, including ER-negative tumors, and rarely associated with HER2-Neu amplification. Our first results obtained in vitro on cell lines and in vivo in tumor xenografts in nude mice, illustrate that the mode of action of cathepsin D in breast cancer is useful to guide the development of these therapies. In the past 20 years we have learned that the action of cathepsin D is complex and involves both intracellular and extracellular activities due to its proteolytic activity and to interactions with membrane components without catalytic activity. Each of these mechanisms could be potentially inhibited in an attempt to prevent tumor growth. Breast cancer is a very heterogeneous and multigenic disease and different targeted therapies adapted to each category of breast cancer are therefore required. Validated assays in the primary tumor of molecular markers such as ER, HER2-Neu and cathepsin D should help to predict which targeted therapy should be applied to cure breast cancer patients.
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PMID:How to target estrogen receptor-negative breast cancer? 1279 Jul 87

The clinical role of HER-2/neu, a 185 kD epithelial transmembranous protein, has evolved after the approval of the anti-HER-2/neu targeted monoclonal antibody trastuzumab (Herceptin) for the therapy of metastatic breast cancer. The extracellular domain of HER-2/neu undergoes proteolytic cleavage from the full-length protein by metalloproteases, and is shed into the blood as a circulating antigen. While HER-2/neu gene amplification and/or protein overexpression are detected in approximately 25% of primary breast cancers, serum HER-2/neu levels are elevated beyond the upper limit of normal in 50 to 60% of stage IV breast cancer patients. HER-2/neu in serum can be detected by enzyme immunoassays (manual and automated versions). It has been shown to have prognostic and predictive information in breast cancer patients. Monitoring for recurrence by serum HER-2/neu reaches a high sensitivity for HER-2/neu positive tumors. Longitudinal follow-up of patients during any kind of systemic therapy allows for monitoring of the therapeutic success. When utilized in these applications, serum HER-2/neu testing is complementary to HER-2/neu tissue results and to the determination of classical tumor markers such as CA 15-3, CA 27.29 and CEA, which are not targeted by specific forms of systemic therapy.
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PMID:Serum HER-2/neu in the management of breast cancer patients. 1281 Jan 50

In this study we describe and discuss the dichotomous effects of docetaxel trastuzumab (Herceptin)/docetaxel therapy on the angiogenic molecular profile in two patients with her-2 + chemo-resistant recurrent breast carcinoma. In the first case, an intensification of angiogenesis occurred following therapy, accompanied by an impressive increase of the cancer cell proliferation index. This tumor did not express HIF1 alpha and shared a HIF-independent VEGF overexpression, which remained unaffected by therapy. An intensified formation of thymidine phosphorylase (TP)-rich stroma, presumably a response to docetaxel, shows a TP-dependent angiogenic response. In the second patient, VEGF and HIF1 alpha were down-regulated in post-treatment biopsies and this was accompanied by a sharp reduction of the vascular density and of the cancer cell proliferation rate. In both cases, c-erbB-2 expression was abrogated by Herceptin. Taking into account that Herceptin down-regulates VEGF through reduction of HIF1 alpha synthesis, this clinical study provides evidence that an anti-angiogenic effect from Herceptin/Docetaxel therapy is expected only in tumors with HIF1 alpha-dependent VEGF overexpression. In contrast, HIF1 alpha-independent VEGF angiogenic activity cannot be abrogated by Herceptin. Docetaxel mediated up-regulation of TP in the tumoral stroma may, on the contrary, result in angiogenesis intersification and rapid tumor relapse. Such an effect should be of clinical importance since Herceptin/Docetaxel-based regimens are currently evaluated for the adjuvant therapy of her-2 + breast cancer patients. Studying the Herceptin-induced phenotypic changes of tumors could lead to the identification of specific molecular profiles that bring about diverging angiogenic responses. Adjustment of the chemotherapy regimen accordingly would prove of clinical importance.
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PMID:The effect of trastuzumab/docatexel combination on breast cancer angiogenesis: dichotomus effect predictable by the HIFI alpha/VEGF pre-treatment status? 1282 Apr 39

The improved understanding of the molecular biology of urothelial malignancies is helping to define the role of new targets and prognostic indices that can direct the most appropriate choice of treatment for advanced disease. Many human tumors express high levels of growth factors and their receptors that can be used as potential therapeutical targets. Tyrosine-kinase receptors, including many growth factor receptors such the receptors for epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and Her2/neu, have been found overexpressed in urothelial tumors. For many of these growth factor receptors, the degree of expression has been associated with the progression of cancer and a poor prognosis. Among the best studied growth factor receptors are the two members of EGF receptor familiy EGFr (ErbB-1), and Her2/neu (ErbB-2). Several preclinical studies in bladder cancer models, have confirmed that systemic administration of growth factor inhibitors inhibits the growth and metastasis of human transitional cell carcinoma established in the bladder wall of athymic nude mice. Additional studies indicate that therapy with EGFR inhibitors enhances the activity of conventional cytoreductive chemotherapeutic agents, in part by inhibiting tumor cell proliferation, angiogenesis, and inducing apoptosis. Novel targeted therapy hold promise to improve the current results of bladder cancer treatment. Based on the success seen with anti-HER2 monoclonal antibodies (Herceptin) and the promising results with EGFR targeted agents (IMC-C225 Cetuximab, ZD1389 Iressa, OSI-774 Tarceva, GW 57016) in other tumor types, and based on the results obtained in preclinical models, there is a great interest in assessing these agents in patients with bladder cancer. Several trials are now ongoing testing these new agents alone or in combination with chemotherapy in bladder cancer patients. The integration of these newer biologic agents, probably to supplement rather than to supplant chemotherapeutic drugs, should be a primary direction of research with the objective to interfere with multiple aspects of bladder cancer progression. However, the value of integration of biologically targeted agents into combined modality treatment for patients with bladder cancer has still to be proven.
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PMID:Novel approaches with targeted therapies in bladder cancer. Therapy of bladder cancer by blockade of the epidermal growth factor receptor family. 1285 May 30

Immunotherapy (biological therapy) comprises such things as active specific immunotherapy ("cancer vaccines"), nonspecific immunostimulation with cytokines, and the inhibition of suppressor influences exerted or elicited by the tumor. Just as cancer chemotherapy began with the use of single agents and evolved into combination therapy, so immunotherapeutic agents have been combined with each other and with chemotherapy. The alkylating agent cyclophosphamide (Cytoxan; CY) has been used for many years to inhibit tumor-derived suppressor influences in rodents, and has been exploited for the same use in humans. Combinations of CY and cancer vaccines such as autologous tumor cells, Melacine, large multivalent immunogen (LMI), and Theratope have been tested with some success in humans for more than a decade. In this use, the CY is a biological response modifier rather than an antitumor agent. Delayed treatment with CY in treating mouse plasmacytomas has proved more effective than immediate treatment, probably because it allows immunity to develop in the host. CY and moderate-dose interleukin-2 (IL-2) have also been a useful regimen in treating human melanomas. IL-2 is itself a useful component of combination immunotherapy, such as with melanoma peptide vaccines, or with interferon-alfa-2b, (IFN-a), as a dual combination or part of a biochemotherapy regimen. IL-2 and histamine, to block reactive oxygen species, may be a more useful combination for treatment of liver metastases of melanoma than IL-2 alone. In this combination, the histamine may permit continued, unimpeded activity of cytolytic T lymphocytes. Several different combinations of drugs and biological agents have been used as biochemotherapy for melanoma, but although there are higher immediate response rates, the long-range survival benefits have been marginal, not justifying the severe toxicity. Combinations of 5-fluorouracil (5-FU) and IFN-a or levamisole have had efficacy in colon and head and neck cancers, but here the biological agents acted as biochemical modulators. Trials of antibodies and chemotherapy have been limited. It appears that trastuzumab (Herceptin) potentiates antitumor therapy in breast cancer and also increases the cardiotoxicity of those regimens.
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PMID:Immunotherapy as part of combinations for the treatment of cancer. 1286 Jan 62

In oncology, the term 'targeted therapy' is used to describe drugs that target only the cancer cells and spare normal cells thereby reducing host toxicity while simultaneously increasing the eradication of cancer. Trastuzumab and imatinib are well known examples of successful targeted therapy. Newer agents like gefitinib and cetuximab offer hope that targeted therapy also may yield therapeutic benefit for such refractory malignancies as lung and colon cancers. One of many remaining challenges is to identify markers, molecular or clinical, that predict for responsiveness to a specific targeted therapy (e.g. HER2/neu positivity and trastuzumab responsiveness). However, using emerging technologies such as gene or protein profiling, it may be possible to predict a tumor's responsiveness to a particular targeted therapy based on its molecular signature. If true, clinicians might then possess the ability to predict a tumor's clinical behavior and shape its density through specific, targeted interventions.
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PMID:Targeted therapy in non-small cell lung cancer: myth or reality. 1286 56


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