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George W Sledge

Publications and source records attributed to George W Sledge.

At least 55 records · Page 3Linked to original sources
PubMed2004

Synthesis of [18F]Xeloda as a novel potential PET radiotracer for imaging enzymes in cancers.

Xeloda (Capecitabine), a prodrug of antitumor agent 5-fluorouracil, is the first and only oral fluoropyrimidine to be approved for use as second-line therapy in metastatic breast cancer, colorectal cancer, and other solid malignancies. Fluorine-18 labeled Xeloda may serve as a novel radiotracer for positron emission tomography (PET) to image enzymes such as thymidine phosphorylase and uridine phosphorylase in cancers. The precursor 2',3'-di-O-acetyl-5'-deoxy-5-nitro-N(4)-(pentyloxycarbonyl)cytidine (11) was synthesized from D-ribose and cytosine in 8 steps with approximately 18% overall chemical yield. The reference standard 5'-deoxy-5-fluoro-N(4)-(pentyloxycarbonyl)cytidine (Xeloda; 1) was synthesized from D-ribose and 5-fluorocytosine in eight steps with approximately 28% overall chemical yield. The target radiotracer 5'-deoxy-5-[(18)F]fluoro-N(4)-(pentyloxycarbonyl)cytidine ([(18)F]Xeloda; [(18)F]1) was prepared by nucleophilic substitution of the nitro-precursor with K(18)F/Kryptofix 2.2.2 followed by a quick deprotection reaction and purification with the HPLC method in 20-30% radiochemical yields.

Animals↗
PubMed2004

Comparative studies of potential cancer biomarkers carbon-11 labeled MMP inhibitors (S)-2-(4'-[11C]methoxybiphenyl-4-sulfonylamino)-3-methylbutyric acid and N-hydroxy-(R)-2-[[(4'-[11C]methoxyphenyl)sulfonyl]benzylamino]-3-methylbutanamide.

(S)-2-(4'-[11C]methoxybiphenyl-4-sulfonylamino)-3-methylbutyric acid ([11C]MSMA) and N-hydroxy-(R)-2-[[(4'-[11C]methoxyphenyl)sulfonyl]benzylamino]-3-methylbutanamide ([11C]CGS 25966), carbon-11 labeled matrix metalloproteinase (MMP) inhibitors, have been synthesized for evaluation as new potential positron emission tomography (PET) cancer biomarkers. [11C]MSMA was prepared by appropriate precursor (S)-2-(4'-hydroxybiphenyl-4-sulfonylamino)-3-methylbutyric acid tert-butyl ester, which was synthesized in eight steps from amino acid (L)-valine in 39.4% chemical yield. This precursor was labeled by [11C]methyl triflate through O-[11C]methylation method at the hydroxyl position of biphenol under basic conditions, followed by a quick acid hydrolysis and isolated by solid-phase extraction (SPE) purification to produce pure target compound [11C]MSMA in 35-55% radiochemical yield, based on 11CO2, decay corrected to end of bombardment (EOB), and 20-25 min synthesis time. [11C]CGS 25966 was prepared in our previous work starting from amino acid (D)-valine. The biodistribution of [11C]MSMA and [11C]CGS 25966 were determined at 45 min post iv injection in breast cancer animal models MCF-7's transfected with IL-1alpha implanted athymic mice and MDA-MB-435 implanted athymic mice. The results showed the uptakes of [11C]MSMA and [11C]CGS 25966 in these tumors were 0.95 and 0.42%dose/g in MCF-7's transfected with IL-1alpha implanted mice, 0.98 and 1.53%dose/g in MDA-MB-435 implanted mice, respectively; the ratios of tumor/muscle (T/M) and tumor/blood (T/B) were 1.21 and 1.09 (T/M, MCF-7's), 0.99 and 0.84 (T/B, MCF-7's), 1.38 and 1.27 (T/M, MDA-MB-435), 1.27 and 1.95 (T/B, MDA-MB-435), respectively. The micro-PET images of [11C]MSMA and [11C]CGS 25966 in both breast cancer athymic mice were acquired for 15 min from a MCF-7's transfected with IL-1alpha and/or MDA-MB-435 implanted mouse at 45 min post iv injection of 1 mCi of the tracer using a dedicated high resolution (<3 mm full-width at half-maximum) small FOV (field-of-view) PET imaging system, Indy-PET II scanner, developed in our laboratory, which showed both tumors were invisible with both tracers. The results were compared. From our results, we concluded that both [11C]MSMA and [11C]CGS 25966 might be unsuitable as PET tracers for cancer imaging.

Animals↗
PubMed2004

Inhibition of breast cancer regrowth and pulmonary metastasis in nude mice by anti-gastric ulcer agent, irsogladine.

Irsogladine is a commonly used anti-gastric ulcer agent in Japan, and recent in vivo studies have shown it to have anti-angiogenic properties. The exact role of irsogladine as an inhibitor of angiogenesis remains uncertain. In this study, we show that irsogladine inhibited breast cancer regrowth and pulmonary metastasis but had no anti-angiogenic function against HUVEC cells. Irsogladine failed to inhibit proliferation, tubular formation, and the uPA/MMP-1 mRNA expression of HUVEC cells. We also examined the effect of irsogladine in an orthotopic transplant model of human breast cancer metastasis in athymic mice. Human MDA-MB-435 cells were injected into the mammary fat pads. After 9 weeks, the tumors were resected under general anesthesia. Irsogladine or vehicle was given p.o. daily thereafter. Daily administration of irsogladine at 120 mg/kg per day over a 5-week period had no effect on the body weight of the mice. Tumor regrowth, average volume of pulmonary metastases, and the number of metastases were inhibited by 40, 48 and 64%, respectively. These results suggest that irsogladine may be useful in the breast cancer adjuvant setting.

Animals↗
PubMed2004

A phase II study of 9-nitro-camptothecin in patients with previously treated metastatic breast cancer.

AIMS: This Phase II study was conducted to determine the efficacy and toxicity of 9-nitro-camptothecin (9-NC) in patients with previously treated metastatic breast cancer. Pharmacokinetic samples were obtained to investigate the correlation of plasma 9-NC exposure with clinical response and toxicity. PATIENTS AND METHODS: Eligible patients had histologically confirmed metastatic breast cancer with measurable or evaluable disease. Patients must have received one or two prior chemotherapy regimens for metastatic disease. 9-NC was given orally, 1.5 mg/m(2)/day for 5 days each week; response was assessed every 8 weeks. Pharmacokinetic samples were obtained on day 1 of weeks 1 and 5. RESULTS: Eighteen patients were enrolled between September 1999 and May 2000; seventeen patients were evaluable for response. The most common toxicities were nausea, vomiting, urinary symptoms, fatigue and diarrhea. No objective responses were observed; six patients had stable disease. 9-NC apparent clearance ranged from 0.57 to 55.08 L/h (median 5.91 L/h); 9-NC area under the curve ranged from 38 to 2130 ng/ml x h (median 377 ng/ml x h). There was no relationship between pharmacokinetic parameters and individual patient toxicity. CONCLUSION: 9-NC has limited activity in patients with previously treated metastatic breast cancer. Though 9-NC has substantial pharmacokinetic variability in this patient population; no correlation was found between pharmacokinetic variables and toxicity.

Antineoplastic Agents↗
PubMed2003

Extracellular proteolysis and cancer: meeting summary and future directions.

The contribution of extracellular proteolysis to processes of tumor invasion and metastasis has been recognized for more than 20 years. However, after millions of dollars and untold hours of investment in preclinical research and the development of broad range inhibitors of MMPs, clinical trials of late-stage tumor patients show no indication that this approach will be successful. In the basic science arena, there have been stunning advancements that illustrate novel biological activities for proteases and that suggest they are key regulators of many physiological and pathological processes. The Proteases and Cancer: Biology and Therapeutics Workshop (held in Bethesda, MD, November 20-22, 2002) was organized by the Division of Cancer Biology, National Cancer Institute (NCI) to identify research areas and directions that will accelerate understanding protease biology and enhance clinical translation. The overall consensus was that protease biology represents fertile ground for advances that will be clinically useful but perhaps not for the reasons or purpose originally thought. Protease-related technologies show particular promise for the detection, prognosis, and prevention of cancer, and for therapeutic purposes in defined situations. Promising areas for further research are identified, and specific recommendations for the development of a consortium to coordinate the efforts of the protease community are made.

Clinical Trials as Topic↗
PubMed2003

Synthesis of radiolabeled biphenylsulfonamide matrix metalloproteinase inhibitors as new potential PET cancer imaging agents.

Novel matrix metalloproteinase (MMP) inhibitor radiotracers, (S)-3-methyl-2-(2',3',4'-methoxybiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1a-c), (S)-3-methyl-2-(2',3',4'-fluorobiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1d-f), and (S)-3-methyl-2-(4'-nitrobiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1g), a series of substituted biphenylsulfonamide derivatives, have been synthesized for evaluation as new potential positron emission tomography (PET) cancer imaging agents.

Biphenyl Compounds↗
PubMed2003

Phase III trial of doxorubicin, paclitaxel, and the combination of doxorubicin and paclitaxel as front-line chemotherapy for metastatic breast cancer: an intergroup trial (E1193).

PURPOSE: Between February 1993 and September 1995, 739 patients with metastatic breast cancer were entered on an Intergroup trial (E1193) comparing doxorubicin (60 mg/m(2)), paclitaxel (175 mg/m(2)/24 h), and the combination of doxorubicin and paclitaxel (AT, 50 mg/m(2) and 150 mg/m(2)/24 h, plus granulocyte colony-stimulating factor 5 mg/kg) as first-line therapy. Patients receiving single-agent doxorubicin or paclitaxel were crossed over to the other agent at time of progression. PATIENTS AND METHODS: Patients were well balanced for on-study characteristics. RESULTS: Responses (complete response and partial response) were seen in 36% of doxorubicin, 34% of paclitaxel, and 47% of AT patients (P =.84 for doxorubicin v paclitaxel, P =.007 for v AT, P =.004 for paclitaxel v AT). Median time to treatment failure (TTF) is 5.8, 6.0, and 8.0 months for doxorubicin, paclitaxel, and AT, respectively (P =.68 for doxorubicin v paclitaxel, P =.003 for doxorubicin v AT, P =.009 for paclitaxel v AT). Median survivals are 18.9 months for patients taking doxorubicin, 22.2 months for patients taking paclitaxel, and 22.0 months for patients taking AT (P = not significant). Responses were seen in 20% of patients crossing from doxorubicin --> paclitaxel and 22% of patients crossing from paclitaxel --> doxorubicin (P = not significant). Changes in global quality-of-life measurements from on-study to week 16 were similar in all three groups. CONCLUSION: (1) doxorubicin and paclitaxel, in the doses used here, have equivalent activity; (2) the combination of AT results in superior overall response rates and time to TTF; and (3) despite these results, combination therapy with AT did not improve either survival or quality of life compared to sequential single-agent therapy.

Adult↗
PubMed2003

Synthesis, biodistribution and micro-PET imaging of a potential cancer biomarker carbon-11 labeled MMP inhibitor (2R)-2-[[4-(6-fluorohex-1-ynyl)phenyl]sulfonylamino]-3-methylbutyric acid [11C]methyl ester.

(2R)-2-[[4-(6-fluorohex-1-ynyl)phenyl]sulfonylamino]-3-methylbutyric acid [(11)C]methyl ester ([(11)C]FMAME), a novel carbon-11 labeled matrix metalloproteinase (MMP) inhibitor, has been synthesized for evaluation as new potential positron emission tomography (PET) cancer biomarker. [(11)C]FMAME was prepared by appropriate precursor (2R)-2-[[4-(6-fluorohex-1-ynyl)phenyl]sulfonylamino]-3-methylbutyric acid (FMA), which was synthesized in six steps from (D)-valine in 71% chemical yield. This acid precursor was labeled by [(11)C]methyl triflate through O-[(11)C]methylation method under basic conditions and isolated by solid-phase extraction (SPE) purification to produce pure target compound in 40-55% radiochemical yield, based on (11)CO(2), decay corrected to end of bombardment, and 15-20 min synthesis time. The biodistribution of [(11)C]FMAME was determined at 30 min post IV injection in breast cancer animal models MCF-7 transfected with IL-1 alpha implanted athymic mice and MDA-MB-435 implanted athymic mice. The results showed the uptakes of [(11)C]FMAME in these tumors were 1.13% dose/g in MCF-7 transfected with IL-1 alpha implanted mice and 1.37% dose/g in MDA-MB-435 implanted mice, respectively; the ratios of tumor/muscle (T/M) and tumor/blood (T/B) were 1.05 +/- 0.29 (T/M, MCF-7's), 0.77 +/- 0.20 (T/B, MCF-7's) and 0.99 +/- 0.35 (T/M, MDA-MB-435), 1.44 +/- 0.69 (T/B, MDA-MB-435), respectively. Pretreatment of MCF-7 transfected with IL-1 alpha tumor-bearing mice with MMP inhibitor FMA had no effect on [(11)C]FMAME biodistribution. Likewise, pretreatment of MDA-MB-435 tumor-bearing mice with FMA also showed no effect on [(11)C]FMAME biodistribution. The micro-PET images were acquired for 15 min from a MCF-7 transfected with IL-1 alpha tumor-bearing mouse or a MDA-MB-435 tumor-bearing mouse at 30 min post IV injection of 1 mCi of [(11)C]FMAME using a dedicated high resolution (<3 mm full-width at half-maximum) PET imaging system (Indy-PET II scanner). The initial dynamic micro-PET images of [(11)C]FMAME in a MCF-7 transfected with IL-1 alpha tumor-bearing mouse during different time periods of 0-15, 15-30, 30-45 and 45-60 min were performed by Indy-PET II. The PET images clearly showed both tumors were visible with [(11)C]FMAME. These results suggest that the localization of [(11)C]FMAME in the tumor is mediated by non-specific processes, and the visualization of [(11)C]FMAME on the tumor using the Indy-PET II scanner is related to non-specific binding.

Animals↗
PubMed2003

Resistance in the anti-angiogenic era: nay-saying or a word of caution?

The hope that anti-angiogenic therapy might be the panacea for cancer has not yet been realized. There are many possible reasons for this, including endothelial and tumor cell heterogeneity, the presence of survival factors within the tumor micro-environment, the problem of defining the best dose and schedule for anti-angiogenic therapies, and angiogenesis-independent regrowth of tumors. Once these problems are understood, we can begin to evaluate approaches to thwarting them. These could include combining anti-angiogenic therapies with chemotherapy, with other anti-angiogenic agents or with other biological therapies. Another approach would be to employ a particular agent or combination of agents that target processes crucial to the survival of a particular cancer.

Angiogenesis Inhibitors↗
PubMed2003

Activity of biphenyl matrix metalloproteinase inhibitor BAY 12-9566 in a human breast cancer orthotopic model.

Matrix metalloproteinases (MMPs) have been implicated in the invasion, metastasis, and angiogenesis associated with human cancer by mediating the degradation of extracellular matrix components. In this paper, we report data that show that BAY 12-9566, a novel inhibitor of MMPs, inhibits angiogenesis, tumor regrowth, and the growth of lung metastases. BAY 12-9566, at 15-100 microM, inhibited tubule formation by human endothelial cells in an in vitro model, but did not prevent the proliferation of endothelial and human breast cancer cells. In the MDA-MB-435 human mammary carcinoma xenograft model, in which the primary tumor is transplanted into the murine mammary fat pad, BAY 12-9566, administered daily at a dose of 100 mg/kg/day p.o. after resection of the primary tumor, inhibited local tumor regrowth by 58% without causing any toxic effect. In addition, BAY 12-9566 treatment inhibited the number and volume of lung metastases by 57 and 88%, respectively. These effects were highly correlated with the serum concentration of BAY 12-9566 at the end of treatment. The serum of the treated animals, harvested 24 h after the last treatment, and the tumor regrown at the site of tumor transplant in the treated animals, contained less protein with MMP-9 activity (as measured in a gelatin zymography assay) than the corresponding controls. However, no difference in the activity of MMP-2 was observed. Although all clinical trials in cancer involving BAY 12-9566 have been halted, this MMP inhibitor has never been used in clinical trials in breast cancer. These results suggest that the novel MMP inhibitor BAY 12-9566 maybe a useful and safe oral treatment for breast cancer, adjunctive to surgery.

Animals↗
PubMed2003

A phase I/II dose-escalation trial of bevacizumab in previously treated metastatic breast cancer.

Vascular endothelial growth factor promotes angiogenesis, an important mediator of growth and metastasis in human breast cancer. Bevacizumab, a monoclonal antibody to vascular endothelial growth factor, is under investigation as an anti-angiogenic agent. This phase I/II trial evaluated the safety and efficacy of bevacizumab in patients with previously treated metastatic breast cancer. Seventy-five patients were treated with escalating doses of bevacizumab ranging from 3 mg/kg to 20 mg/kg administered intravenously every other week. Tumor response was assessed before the sixth (70 days) and 12th (154 days) doses. Safety was evaluated during every cycle. Eighteen patients were treated at 3 mg/kg, 41 at 10 mg/kg, and 16 at 20 mg/kg. Four patients discontinued study treatment because of an adverse event. Hypertension was reported as an adverse event in 17 patients (22%). The overall response rate was 9.3% (confirmed response rate, 6.7%). The median duration of confirmed response was 5.5 months (range, 2.3 to 13.7 months). At the final tumor assessment on day 154, 12 of 75 patients (16%) had stable disease or an ongoing response. The optimal dose of bevacizumab in this trial was 10 mg/kg every other week and toxicity was acceptable. These data support the initiation of trials in metastatic breast cancer combining bevacizumab with chemotherapy.

Adult↗
PubMed2003

Gemcitabine combined with paclitaxel or paclitaxel/trastuzumab in metastatic breast cancer.

The combination of gemcitabine and paclitaxel in metastatic breast cancer is attractive because of the good single-agent activity of each, the different mechanisms of antitumor effect, and the, generally, nonoverlapping toxicity profiles of the agents. Phase II trials of the combination indicate response rates of 45% to 55% and median survival of 12 months in extensively pretreated patients, including those with anthracycline-resistant disease, and a response rate of 69% in patients with newly recurrent metastatic breast cancer. The combination was well tolerated, with severe hematologic toxicity being infrequent. The combination of gemcitabine, paclitaxel, and trastuzumab in patients with HER2-positive metastatic breast cancer with no prior chemotherapy in the metastatic setting produced a response rate of 71% and median response duration of 11 months. The combination was safe and well tolerated, with no unexpected toxicities being observed. Both combinations warrant additional study in metastatic breast cancer.

Antibodies, Monoclonal↗