bluuebunny/crossref_metadata_2025 huggingface dataset:
Is There a Role for Adjuvant Tamoxifen in Progesterone Receptor–Positive Breast Cancer? An In silico Clinical Trial
Authors: Hilsenbeck Susan G. , Osborne C. Kent
Published: March 2006

Purpose: Subset analysis from the Arimidex, Tamoxifen, Alone or in Combination trial, a major adjuvant therapy trial, suggests that progesterone receptor–negative (PR−) cases may derive greater benefit from aromatase inhibitor compared with tamoxifen than PR+ cases. We postulated that estrogen receptor–positive (ER+)/PR+ patients might do as well or better by starting on tamoxifen and later switching to an aromatase inhibitor rather than by starting on an aromatase inhibitor as initial therapy.

Experimental Design: We constructed a computer model using retrospective data to approximate exponential failure rates for PR+ and PR− in tamoxifen-treated and tamoxifen-untreated patients, adding the assumptions that about half of patients are cured at surgery and that ∼20% of postmenopausal ER+ early breast cancer cases are PR−. This model provided a very good approximation to the published overview data and to the clinical trials. We then used the failure rates to generate relapse times for a large number of cases (n = 50,000) for each treatment scenario.

Results: In PR− cases, initial therapy with an aromatase inhibitor is superior to tamoxifen and this advantage can never be made up by switching. In PR+ cases, tamoxifen is only modestly inferior to aromatase inhibitor at the outset, and after switching to an aromatase inhibitor at 3 or 5 years the tamoxifen relapse-free survival curve catches up and then begins to surpass the aromatase inhibitor curve at 7.5 or 12 years, respectively.

Discussion: Although our in silico trial is based on many assumptions, it closely approximates results of the published trials and, therefore, suggests that an in vivo comparison in ER+/PR+ patients of aromatase inhibitor versus tamoxifen followed by aromatase inhibitor may be worth considering.
Avidity-Mediated Enhancement of In vivo Tumor Targeting by Single-Chain Fv Dimers
Authors: Adams Gregory P. , Tai Mei-Sheng , McCartney John E. , Marks James D. , Stafford Walter F. , Houston L.L. , Huston James S. , Weiner Louis M.
Published: March 2006

Radiolabeled single-chain Fv (sFv) molecules display highly specific tumor retention in the severe combined immunodeficient (SCID) mouse model; however, the absolute quantity of sFv retained in the tumors is diminished by the rapid renal elimination resulting from the small size of the sFv molecules (Mr 27,000) and by dissociation of the monovalent sFv from tumor-associated antigen. We previously reported significant improvement in tumor retention without a loss of targeting specificity on converting monovalent sFv into divalent [(sFv′)2] dimers, linked by a disulfide bond between COOH-terminal cysteinyl peptides engineered into the sFv′. However, our data for enhanced dimer localization in tumors could not distinguish between the contributions of enhanced avidity and increased systemic retention associated with the larger size of 54 kDa [(sFv′)2] dimers relative to 27-kDa sFv. In this investigation, we have compared tumor targeting of divalent anti-c-erbB-2/HER2/neu 741F8-1 (sFv′)2 homodimers with monovalent 741F8/26-10 (sFv′)2 heterodimers (Mr 54,000) and 741F8 sFv monomers (741F8 sFv has binding specificity for erbB-2/HER2/neu and 26-10 sFv specificity for digoxin and related cardiac glycosides). These studies allowed us to distinguish the dominant effect of valency over molecular weight in accounting for the superior tumor retention of 741F8-1 (sFv′)2 homodimers. Each of the radioiodinated species was administered i.v. to SCID mice bearing SK-OV-3 human tumor xenografts and tumor localization at 24 hours post i.v. injection was determined for 125I-741F8-1 (sFv′)2 (3.57 %ID/g), 125I-741F8/26-10 (sFv′)2 (1.13 %ID/g), and 125I-741F8-1 sFv (1.25 %ID/g). These findings substantiate that the improved tumor retention of (sFv′)2 homodimers over sFv monomers results from the availability of dual binding sites rather than from the slower systemic clearance of homodimers.
A Phase I Trial of Vaccination of CA9-Derived Peptides for HLA-A24-Positive Patients with Cytokine-Refractory Metastatic Renal Cell Carcinoma
Authors: Uemura Hirotsugu , Fujimoto Kiyohide , Tanaka Motoyoshi , Yoshikawa Motoyoshi , Hirao Yoshihiko , Uejima Shigeya , Yoshikawa Kazuhiro , Itoh Kyogo
Published: March 2006

Purpose: A phase I peptide vaccination trial was done in patients with progressive cytokine-refractory metastatic renal cell carcinoma (RCC) to assess both the toxicity and capability to induce immune responses of three peptides (CA9p219-227, p288-296, and p323-331) derived from CA9, a tumor-associated antigen ubiquitously expressed in RCC.

Experimental Design: Twenty-three patients positive for human leukocyte antigen (HLA)-A24 with histologically confirmed RCC were enrolled. Eligibility included progressive disease after standard cytokine therapy with interleukin-2 and/or IFN-α. Patients were vaccinated s.c. with the three peptides emulsified in incomplete Freund's adjuvant at 2-week intervals. Pre- and post-vaccination blood samples were obtained for toxicity assessment and immunologic studies. Patients were monitored for clinical responses on a 3-monthly basis.

Results: Vaccinations were well tolerated without any major adverse event. Most of the patients developed peptide-specific CTLs and/or immunoglobulin G reactive to the peptides after the 6th or 9th vaccination, followed by a gradual increase in both CTL frequency and levels of peptide-reactive serum IgG. Three patients with multiple lung metastases showed partial responses with disappearance and shrinking of metastatic lesions. Additionally, stable disease for >6 months was observed in six patients (median duration, 12.2 months). Moreover, the median survival time of all patients who were progressive at trial enrollment after failing immunotherapy was 21.0 months (5-35 months).

Conclusions: These results suggest that vaccination of these peptides is safe and recommended for further trials for HLA-A24-positive metastatic RCC patients.
Neoadjuvant Concurrent Paclitaxel and Radiation in Stage II/III Breast Cancer
Authors: Chakravarthy A. Bapsi , Kelley Mark C. , McLaren Bernadette , Truica Cristina I. , Billheimer Dean , Mayer Ingrid A. , Grau Ana M. , Johnson David H. , Simpson Jean F. , Beauchamp R. Daniel , Jones Catherine , Pietenpol Jennifer A.
Published: March 2006

Purpose: The aim of this study was to determine the safety and pathologic response rates following neoadjuvant paclitaxel and radiation in patients with stage II/III breast cancer and to evaluate the use of sequential biopsies to allow an in vivo assessment of biological markers as potential predictive markers of response to this regimen.

Patients and Methods: Patients with high-risk, operable breast cancer were treated with three cycles of paclitaxel 175 mg/m2 every 3 weeks, followed by twice-weekly paclitaxel 30 mg/m2 and concurrent radiation. Core biopsies were obtained at baseline and 24 to 72 hours after the first cycle of paclitaxel. After completing neoadjuvant treatment, patients underwent definitive surgery. The primary end point was pathologic complete response, which is defined as the absence of any invasive cancer at surgery. Potential markers of therapeutic response were evaluated including markers of proliferation, apoptosis, p21, HER2, estrogen receptor, and progesterone receptor status.

Results: Of the 38 patients enrolled, 13 (34%) had a pathologic complete response. There was no significant difference in baseline Ki-67 between responders (35%) and nonresponders (28%; P = 0.45). There was also no significant change in Ki-67 following paclitaxel administration. Despite this lack of immunohistologic change in proliferative activity, baseline mitotic index was higher for patients with pathologic complete response over nonresponders (27 versus 10, P = 0.003). Moreover, the increase in mitotic index following paclitaxel administration was associated with pathologic complete response.

Conclusions: Neoadjuvant paclitaxel/radiation is effective and well tolerated. Tumor proliferation at baseline and response to chemotherapy as measured by mitotic activity may serve as an important indicator of pathologic response to neoadjuvant paclitaxel/radiation.
The Clinical Relevance of Stromal Matrix Metalloproteinase Expression in Ovarian Cancer
Authors: Kamat Aparna A. , Fletcher Mavis , Gruman Lynn M. , Mueller Peter , Lopez Adriana , Landen Charles N. , Han Liz , Gershenson David M. , Sood Anil K.
Published: March 2006

Purpose: Matrix metalloproteinases (MMP) are proteolytic enzymes implicated in cancer progression and metastasis. We sought to determine the role of epithelial (tumor cell–derived) and stromal (host-derived) expression of MMPs in predicting the clinical outcome of patients with epithelial ovarian cancer (EOC).

Experimental Design: MMP-2, MMP-9, and membrane type 1 (MT1)-MMP expression was evaluated using immunohistochemistry in 90 invasive EOCs, and samples were scored for epithelial and stromal staining. Results were correlated with clinicopathologic characteristics using univariate and multivariate analyses.

Results: High expression of MMP-2, MMP-9, and MT1-MMP in tumor epithelium was detected in 54%, 97%, and 100% of cases, and in stromal compartments, in 38%, 70%, and 38% of cases, respectively. High stromal expression of MMP-2, MMP-9, and MT1-MMP was significantly associated with aggressive features such as high stage, high grade ascites, and positive lymph node status. Kaplan-Meier analysis showed that high epithelial and stromal expression of MMP-2, MMP-9, and MT1-MMP were each significantly associated with shorter disease-specific survival (DSS; P < 0.01). On tree-structured survival analysis, patients with strong epithelial MT1-MMP expression had the shortest DSS, whereas patients with moderate epithelial MT1-MMP and low stromal MMP-9 expression had the longest DSS (P < 0.01). On multivariate analysis, high stromal expression of MMP-9 (P = 0.01) and MT1-MMP (P = 0.04), strong epithelial MT1-MMP (P = 0.01) and high stage (P = 0.04) were independent predictors of poor DSS.

Conclusions: Overexpression of stromal MMP-9 and MT1-MMP is independently associated with shorter DSS in EOC. Thus, host-derived MMPs are valuable predictors of clinical outcome in EOC.
BRAF Is a Therapeutic Target in Aggressive Thyroid Carcinoma
Authors: Salvatore Giuliana , De Falco Valentina , Salerno Paolo , Nappi Tito Claudio , Pepe Stefano , Troncone Giancarlo , Carlomagno Francesca , Melillo Rosa Marina , Wilhelm Scott M. , Santoro Massimo
Published: March 2006

Purpose: Oncogenic conversion of BRAF occurs in ∼44% of papillary thyroid carcinomas and 24% of anaplastic thyroid carcinomas. In papillary thyroid carcinomas, this mutation is associated with an unfavorable clinicopathologic outcome. Our aim was to exploit BRAF as a potential therapeutic target for thyroid carcinoma.

Experimental Design: We used RNA interference to evaluate the effect of BRAF knockdown in the human anaplastic thyroid carcinoma cell lines FRO and ARO carrying the BRAF V600E (V600EBRAF) mutation. We also exploited the effect of BAY 43-9006 [N-(3-trifluoromethyl-4-chlorophenyl)-N'-(4-(2-methylcarbamoyl pyridin-4-yl)oxyphenyl)urea], a multikinase inhibitor able to inhibit RAF family kinases in a panel of six V600EBRAF-positive thyroid carcinoma cell lines and in nude mice bearing ARO cell xenografts. Statistical tests were two sided.

Results: Knockdown of BRAF by small inhibitory duplex RNA, but not control small inhibitory duplex RNA, inhibited the mitogen-activated protein kinase signaling cascade and the growth of ARO and FRO cells (P < 0.0001). These effects were mimicked by thyroid carcinoma cell treatment with BAY 43-9006 (IC50 = 0.5-1 μmol/L; P < 0.0001), whereas the compound had negligible effects in normal thyrocytes. ARO cell tumor xenografts were significantly (P < 0.0001) smaller in nude mice treated with BAY 43-9006 than in control mice. This inhibition was associated with suppression of phospho–mitogen-activated protein kinase levels.

Conclusions: BRAF provides signals crucial for proliferation of thyroid carcinoma cells spontaneously harboring the V600EBRAF mutation and, therefore, BRAF suppression might have therapeutic potential in V600EBRAF-positive thyroid cancer.
Proteomic Analysis of Malignant Ovarian Cancer Effusions as a Tool for Biologic and Prognostic Profiling
Authors: Davidson Ben , Espina Virginia , Steinberg Seth M. , Flørenes Vivi Ann , Liotta Lance A. , Kristensen Gunnar B. , Tropé Claes G. , Berner Aasmund , Kohn Elise C.
Published: March 2006

Purpose: Malignant epithelial ovarian cancer effusions are important in disease dissemination and clinical outcome. The identification of biochemical events active in effusions may improve our identification and application of targeted therapeutics.

Experimental Design: Archival effusion samples for which outcome information was known were studied. Clinical variables were comparable between these groups. Two cohorts of patients with malignant effusion were assessed: those with effusion at presentation (Tap1) or at first recurrence (Tap2). Expression and activated fraction of selected signaling proteins were quantitated on serial protein microarrays using validated antibodies. Proteomic results and clinical variables were analyzed by univariate analysis followed by Cox proportional hazards model analysis.

Results: Malignant effusions (>80% malignant cells) were distinguished from benign effusions by higher expression of AKT, activated extracellular signal-regulated kinase, activated (P ≤ 0.001) and total cAMP-responsive element binding protein (P = 0.01), and JNK (P = 0.03). Malignant pleural effusions could not be differentiated from ascites by signaling profiles. Both had signal expression clusters for survival, proliferation and metastasis, and injury pathways. Cox proportional hazards model analysis revealed high p38 and pEGFR/EGFR ratio as jointly associated with poor survival in Tap1 cases (both P ≤ 0.002). Phospho-JNK quantity was associated with worse outcome in Tap2 patients (P = 0.004), when taking other factors into consideration.

Conclusions: Proliferation, survival, and apoptosis signaling dysregulation can be identified in ovarian cancer effusion samples. Biochemical characterization of clinical effusions may provide either predictive and/or correlative information on patient outcome from which to further understand the mechanisms of effusion development and target clinical intervention.
Full-Dose 90Y Ibritumomab Tiuxetan Therapy Is Safe in Patients with Prior Myeloablative Chemotherapy
Authors: Jacobs Samuel A. , Vidnovic Nicholas , Joyce Judith , McCook Barry , Torok Frank , Avril Norbert
Published: March 2006

Purpose: Targeted radioimmunotherapy with yttrium-90 (90Y)–labeled ibritumomab tiuxetan (Zevalin, IDEC-Biogen, San Diego, CA) has shown significant activity in the treatment of relapsed or refractory CD20+ non–Hodgkin's lymphoma. Eligibility criteria used in phase I trials, and adopted in phase II and III trials, excluded patients with prior myeloablative therapy. We treated eight patients with 90Y ibritumomab tiuxetan who had prior autologous stem cell transplant, but met all other treatment criteria.

Experimental Design: Eight patients with CD20+ non–Hodgkin's lymphoma had extensive prior therapy including myeloablative chemotherapy but did not receive total body irradiation. Each had bone marrow cellularity of >15%, platelet count of >100,000/mm3, and one had documented lymphomatous bone marrow involvement of <25%. The standard course of 0.3 to 0.4 mCi/kg of 90Y ibritumomab tiuxetan was administered to patients at full dose. 18-Flouro-deoxyglucose positron emission tomography/computed tomography scans were done at pretreatment and ∼12 weeks after treatment to assess patient response. Maximum toxicities were monitored and classified according to the Common Terminology Criteria for Adverse Events (ver. 3.0).

Results: Toxicities observed included grade 4 thrombocytopenia in three of eight evaluable patients and grade 4 neutropenia in one of eight evaluable patients. One patient had a neutropenic fever; all patients were off blood product support 12 weeks post-zevalin. Complete response by 18-flouro-deoxyglucose positron emission tomography/computed tomography imaging occurred in one of seven evaluable patients and one patient treated as consolidation had no evidence of disease.

Conclusion: Our experience suggests that 90Y ibritumomab tiuxetan treatment is safe for use in patients with prior myeloablative therapy when the general inclusion criteria are fulfilled. In this small series, the response rates, however, are limited. Nevertheless, 90Y ibritumomab tiuxetan treatment may provide clinical benefit in carefully selected extensively pretreated patients.
Determining Maximal Tolerable Dose of the Monoclonal Antibody BR96 Labeled with 90Y or 177Lu in Rats: Establishment of a Syngeneic Tumor Model to Evaluate Means to Improve Radioimmunotherapy
Authors: Mårtensson Linda , Wang Zhongmin , Nilsson Rune , Ohlsson Tomas , Senter Peter , Sjögren Hans-Olov , Strand Sven-Erik , Tennvall Jan
Published: March 2006

Purpose: To evaluate therapeutic strategies, it is essential to use biological models reflecting important aspects of the clinical situation. The aim of the present study was to compare the maximal tolerable dose of the monoclonal antibody BR96 labeled with 90Y or 177Lu in immunocompetent rats. Maximal tolerable dose was defined as the highest activity that allows 100% of the animals to survive without clinical signs, such as infections, bleeding, or diarrhea, and with <20% loss in body weight.

Experimental Design: Increasing activity levels of BR96 labeled with 90Y or 177Lu were administered to groups of rats. Blood parameters, body weight, and general performance were monitored for 8 weeks.

Results: Two days postinjection, all groups had decreased leukocyte counts down to 5% to 15% of initial values. Initiation of recovery (at 14-21 days) showed a dose-response relationship. All groups, except the group given the highest activity of 90Y, had complete resolution in their leukopenia. The decrease in platelets was delayed to days 7 to 14 postinjection with a dose-dependent response regarding both severity of the nadir (10-40% of initial value) and the start of recovery. Animals in the groups given the highest activities of both 90Y and 177Lu exhibited skin infections on day 21.

Conclusions: The results showed good reproducibility and dose-dependent toxicity for both radionuclides, indicating that the maximal tolerable dose for 177Lu–BR96 (1,000 MBq/kg) is 1.7 times that for 90Y–BR96 (600 MBq/kg) in rats. This model makes it feasible to evaluate strategies to escalate therapeutic doses to tumors without increasing normal tissue toxicity.
Pretargeting of Carcinoembryonic Antigen–Expressing Tumors with a Biologically Produced Bispecific Anticarcinoembryonic Antigen × Anti-Indium–Labeled Diethylenetriaminepentaacetic Acid Antibody
Authors: van Schaijk Frank G. , Oosterwijk Egbert , Soede Annemieke C. , Broekema Matthias , Frielink Cathelijne , McBride William J. , Goldenberg David M. , Corstens Frans H.M. , Boerman Otto C.
Published: March 2006

Purpose: The aim of these studies was to develop a pretargeting strategy for CEA-expressing cancers using biologically produced bispecific monoclonal antibodies (bsMAb). The bsMAbs used in this system have affinity for the carcinoembryonic antigen on the one hand, and for indium-labeled diethylenetriaminepentaacetic acid (DTPA), on the other.

Experimental Design: Stable quadroma clones producing bsMAb MN-14xDTIn-1 were isolated. LS174T tumor–bearing mice were injected with 1 to 100 μg of bsMAb followed by 1 to 60 ng of an 111In-labeled bivalent peptide [Ac-Phe-Lys(DTPA)-Tyr-Lys(DTPA)-NH2]. Mice were killed at 24 hours postinjection and the biodistribution of the radiolabel was determined. The biodistribution of diDTPA labeled with four different radionuclides (111In, 99mTc, nonresidualizing 125I, and residualizing 125I) was determined at various time points postinjection following pretargeting of LS174T tumors with bsMAb MN-14xDTIn-1.

Results: Optimal tumor targeting was observed when tumors were pretargeted with 10 μg of bsMAb MN-14xDTIn-1 and when 6 ng of a radiolabeled peptide was given 72 hours later. The uptake of the four radiolabels in LS174T tumors at 4 hours postinjection was similar. However, at later time points, the 111In-label and residualizing 125I-label were better retained in the tumor than the nonresidualizing 125I label. Although the absolute uptake in the tumor (in terms of percentage of injected dose per gram of tissue) was 5-fold lower than the uptake obtained with directly labeled MN-14, the pretargeting strategy revealed much higher tumor-to-blood ratios due to the rapid clearance of the radiolabel from the circulation as compared with 111In-MN-14 (445 ± 90 and 5.3 ± 1.1, respectively, at 72 hours postinjection).

Conclusions: Effective targeting of carcinoembryonic antigen-expressing tumors was achieved with a newly produced bispecific antibody. The 111In-labeled l-amino acid peptide and 125I-d-amino acid peptide were better retained in the tumor than the 99mTc- and 125I-l-amino acid peptide. Very high tumor-to-blood ratios were obtained due to rapid background clearance.
Improved Tumor Targeting by Combined Use of Two Antitenascin Antibodies
Authors: Petronzelli Fiorella , Pelliccia Angela , Anastasi Anna Maria , D'Alessio Valeria , Albertoni Claudio , Rosi Antonio , Leoni Barbara , De Angelis Clara , Paganelli Giovanni , Palombo Giovanna , Dani Maria , Carminati Paolo , De Santis Rita
Published: March 2006

Purpose: In the pretargeted antibody-guided radioimmunotherapy (PAGRIT) system, the combined use of two different antibodies directed against the same tumor antigen could represent a valid approach for improving tumor targeting and therapeutic efficacy. We developed a novel monoclonal antitenascin antibody, ST2485, and studied its biochemical and functional properties by in vitro and in vivo assays. We then investigated the first of the three-step therapy combining ST2485 with another antitenascin antibody, ST2146, previously described, to increase accumulation of biotinylated antibodies at the tumor site.

Experimental Design: Studies of immunoreactivity, affinity, immunohistochemistry, and biodistribution in xenograft model were carried out on ST2485. Analysis of the ST2485 and ST2146 combination was preliminary carried out by ELISA and BiaCore tests and then by in vivo distribution studies after administration of the radiolabeled biotinylated antibodies, followed by a chase with avidin as clearing agent.

Results: ST2485 was found to be a suitable antibody for therapeutic applications. Indeed, for its behavior in all tests, it was comparable with ST2146 and better than BC2, an antibody already used for clinical trials. The additivity of ST2146 and ST2485 in tenascin C binding, shown by in vitro tests, was confirmed by biodistribution studies in a xenograft model where tumor localization of the antibodies was near the sum of each antibody alone, with a tumor-to-blood ratio higher than 24.

Conclusion: The results reported in this study suggest that a monoclonal antitenascin antibody mixture can improve tumor targeting. This strategy could represent progress for therapeutic approaches such as PAGRIT.
Direct Antilymphoma Effects on Human Lymphoma Cells of Monotherapy and Combination Therapy with CD20 and HLA-DR Antibodies and 90Y-Labeled HLA-DR Antibodies
Authors: DeNardo Gerald L. , Tobin Evan , Chan Kaylund , Bradt Bonnie M. , DeNardo Sally J.
Published: March 2006

Purpose: Monoclonal antibodies (mAb) in combination and mAbs combined with a radionuclide (radioimmunotherapy) have both been more effective in patients than mAb monotherapy.

Experimental Design: Using assays of cell growth and viability, the dose response and temporal characteristics of CD20 (rituximab) and HLA-DR (Lym-1) mAbs, singly and in combination, and of 90Y-conjugated Lym-1 mAb have been characterized in five human lymphoma cell lines (B35M, Raji, SU-DHL-4, SU-DHL-6, and Ramos) spanning Burkitt's to diffuse large cell lymphoma. Although Ramos had a lower HLA-DR density, these cell lines were otherwise selected because of high cell surface CD20 and HLA-DR abundance. Assays of cell growth and death were done using microscopy and trypan blue dye.

Results: Lym-1 and rituximab, used singly, showed direct antilymphoma effects; those of Lym-1 were often more potent than those of rituximab. Combinations of these mAbs were more effective, sometimes synergistic, than either mAb singly, even in more resistant SU-DHL-4 cells. Conjugation of 90Y to Lym-1 also augmented potency in all cell lines and overcame resistance to both Lym-1 and rituximab in Ramos cells.

Conclusions: Lym-1 exhibited substantially greater direct antilymphoma effects than rituximab in lymphoma cells in culture. Combination of Lym-1 with rituximab or 90Y increased potency and overcame treatment resistance in lymphoma cells. Greater use of combination therapies of this type to increase potency and range of effectiveness seems likely to improve patient outcome.
Radioimmunotherapy with [131I]cG250 in Patients with Metastasized Renal Cell Cancer: Dosimetric Analysis and Immunologic Response
Authors: Brouwers Adrienne H. , Buijs Wilhelmina C.A.M. , Mulders Peter F.A. , de Mulder Pieter H.M. , van den Broek Wim J.M. , Mala Carola , Oosterwijk Egbert , Boerman Otto C. , Corstens Frans H.M. , Oyen Wim J.G.
Published: March 2006

Purpose: A study was designed to define the therapeutic efficacy, safety, and toxicity of two sequential high-dose treatments of radioimmunotherapy with [131I]cG250 in patients with metastasized renal cell carcinoma. Here, we report the dosimetric analysis and the relationship between the development of a human antichimeric antibody response and altered pharmacokinetics.

Experimental Design: Patients (n = 29) with progressive metastatic renal cell carcinoma received a low dose (222 MBq) of [131I]cG250 for dosimetric analysis, followed by the first radioimmunotherapy with 2,220 MBq/m2 [131I]cG250 (n = 27) 1 week later. If no grade 4 hematologic toxicity was observed, a second low dose of [131I]cG250 (n = 20) was given 3 months later. Provided that no accelerated blood clearance was observed, a second radioimmunotherapy of [131I]cG250 was administered at an activity-dose level of 1,110 MBq/m2 (n = 3) or 1,665 MBq/m2 (n = 16). After each administration, whole-body images were obtained and the pharmacokinetics and the development of human antichimeric antibody responses were determined. Radiation-absorbed doses were calculated for whole body, red marrow, organs, and metastases.

Results: No correlation was found between hematologic toxicity and radiation-absorbed dose to the whole body or bone marrow, nor administered activity (MBq and MBq/kg). The tumor-absorbed doses varied largely. An inverse relation between tumor size and radiation-absorbed dose was found. Most tumor lesions received <10 Gy, whereas only lesions <5 g absorbed >50 Gy. A relatively high number of patients developed a human antichimeric antibody response (8 of 27) with altered pharmacokinetics, hampering additional radioimmunotherapies in four of these patients.

Conclusions: Dosimetric analysis did not adequately predict the degree of bone marrow toxicity. When human antichimeric antibody developed, the rapid clearance of radioactivity from the blood and body prohibited further treatment. According to the calculated absorbed dose in metastatic lesions, future radioimmunotherapy studies with radiolabeled cG250 should aim at treatment of small-volume disease or treatment in an adjuvant setting.
Nuclear Imaging of Met-Expressing Human and Canine Cancer Xenografts with Radiolabeled Monoclonal Antibodies (MetSeekTM)
Authors: Hay Rick V. , Cao Brian , Skinner R. Scot , Su Yanli , Zhao Ping , Gustafson Margaret F. , Qian Chao-Nan , Teh Bin T. , Knudsen Beatrice S. , Resau James H. , Shen Shuren , Waters David J. , Gross Milton D. , Vande Woude George F.
Published: March 2006

Purpose: Met, an oncogene product and receptor tyrosine kinase, is a keystone molecule for malignant progression in solid human tumors. We are developing Met-directed imaging and therapeutic agents, including anti-Met monoclonal antibodies (MetSeekTM). In this study, we compared two antibodies, Met5 and Met3, for nuclear imaging of human and canine Met-expressing tumor xenografts in nude mice.

Experimental Design: Xenografts representing cancers of three different human tissue origins and metastatic canine prostate cancer were raised s.c. in host athymic nude mice. Animals were injected i.v. with I-125-Met5 or I-125-Met3, posterior total body gamma camera images were acquired for several days postinjection, and quantitative region-of-interest activity analysis was done.

Results: PC-3, SK-LMS-1/HGF, and CNE-2 xenografts imaged with I-125-Met5 were compared with PC-3, SK-LMS-1/HGF, and DU145 xenografts imaged with I-125-Met3. Nuclear imaging contrast was qualitatively similar for I-125-Met5 and I-125-Met3 in PC-3 and SK-LMS-1/HGF host mice. However, by region-of-interest analysis, the set of human tumors imaged with I-125-Met3 exhibited a pattern of rapid initial tumor uptake followed by a continuous decline in activity, whereas the set of human tumors imaged with I-125-Met5 showed slow initial uptake, peak tumor-associated activity at 1 day postinjection, and persistence of activity in xenografts for at least 5 days. GN4 canine prostate cancer xenografts were readily imaged with I-125-Met5.

Conclusions: We conclude that radioiodinated Met3 and Met5 offer qualitatively similar nuclear images in xenograft-bearing mice, but quantitative considerations indicate that Met5 might be more useful for radioimmunotherapy. Moreover, canine prostate cancer seems to be a suitable model for second-stage preclinical evaluation of Met5.
Application of High Amplitude Alternating Magnetic Fields for Heat Induction of Nanoparticles Localized in Cancer
Authors: Ivkov Robert , DeNardo Sally J. , Daum Wolfgang , Foreman Allan R. , Goldstein Robert C. , Nemkov Valentin S. , DeNardo Gerald L.
Published: March 2006

Objective: Magnetic nanoparticles conjugated to a monoclonal antibody can be i.v. injected to target cancer tissue and will rapidly heat when activated by an external alternating magnetic field (AMF). The result is necrosis of the microenvironment provided the concentration of particles and AMF amplitude are sufficient. High-amplitude AMF causes nonspecific heating in tissues through induced eddy currents, which must be minimized. In this study, application of high-amplitude, confined, pulsed AMF to a mouse model is explored with the goal to provide data for a concomitant efficacy study of heating i.v. injected magnetic nanoparticles.

Methods: Thirty-seven female BALB/c athymic nude mice (5-8 weeks) were exposed to an AMF with frequency of 153 kHz, and amplitude (400-1,300 Oe), duration (1-20 minutes), duty (15-100%), and pulse ON time (2-1,200 seconds). Mice were placed in a water-cooled four-turn helical induction coil. Two additional mice, used as controls, were placed in the coil but received no AMF exposure. Tissue and core temperatures as the response were measured in situ and recorded at 1-second intervals.

Results: No adverse effects were observed for AMF amplitudes of ≤700 Oe, even at continuous power application (100% duty) for up to 20 minutes. Mice exposed to AMF amplitudes in excess of 950 Oe experienced morbidity and injury when the duty exceeded 50%.

Conclusion: High-amplitude AMF (up to 1,300 Oe) was well tolerated provided the duty was adjusted to dissipate heat. Results presented suggest that further tissue temperature regulation can be achieved with suitable variations of pulse width for a given amplitude and duty combination. These results suggest that it is possible to apply high-amplitude AMF (>500 Oe) with pulsing for a time sufficient to treat cancer tissue in which magnetic nanoparticles have been embedded.
Fractionated Locoregional Low-Dose Radioimmunotherapy Improves Survival in a Mouse Model of Diffuse-Type Gastric Cancer Using a 213Bi-Conjugated Monoclonal Antibody
Authors: Bloechl Stefanie , Beck Roswitha , Seidl Christof , Morgenstern Alfred , Schwaiger Markus , Senekowitsch-Schmidtke Reingard
Published: March 2006

Purpose: Locoregional radioimmunotherapy of i.p. tumor cell dissemination of diffuse-type gastric cancer using the α-emitter 213Bi displayed good therapeutic results after a single application depending on the time interval between tumor cell inoculation and injection of the 213Bi-immunoconjugate. The aim of the present study was to compare single versus double i.p. injection of a tumor-specific antibody (d9MAb) conjugated with low activities of 213Bi in terms of therapeutic efficacy and toxicity.

Experimental Design: Nude mice were inoculated i.p. with 1 × 107 human gastric cancer cells (HSC45-M2) expressing tumor-specific mutant d9-E-cadherin (d9-E-cad). After tumor cell inoculation, the mice were injected i.p. with a single injection at day 1 or 8, or double injections at days 1 and 8 or days 8 and 15 with 0.37, 0.74, or 1.48 MBq 213Bi-d9MAb. Therapeutic efficacy was determined by median survival, and toxicity was evaluated by leukocyte and platelet counts. The development of i.p. carcinomatosis was monitored by carcinoembryonic antigen concentrations in the serum of the mice.

Results: The median survival of treated animals increased, depending on the time interval (days) between tumor cell inoculation and therapy, and the injected activity, from 22 days of untreated mice to 48 days (0.37 MBq, 1 day), 84 days (0.37 MBq, 1 and 8 days), 37 days (0.37 MBq, 8 days), 46 days (0.37 MBq, 8 and 15 days), 42 days (0.74 MBq, 8 days), 78 days (0.74 MBq, 8 and 15 days), and 44 days (1.48 MBq, 8 days). The injected activities did not reduce leukocyte and platelet counts. Carcinoembryonic antigen, which was not detectable in the serum of tumor-free mice, increased after tumor cell inoculation and tumor proliferation and decreased after each therapeutic application of 213Bi-d9MAb.

Conclusions: Double application of only 0.37 MBq of 213Bi-d9MAb at days 1 and 8 after tumor cell inoculation significantly prolonged median survival in nude mice suffering from i.p. tumor cell dissemination compared with a single injection. Even in an advanced stage of the disease, double injection of 0.74 MBq at days 8 and 15 was superior to a single injection of 1.48 MBq at day 8 without any sign of toxicity.
Pretargeting of Carcinoembryonic Antigen–Expressing Cancers with a Trivalent Bispecific Fusion Protein Produced in Myeloma Cells
Authors: Rossi Edmund A. , Chang Chien-Hsing , Losman Michele J. , Sharkey Robert M. , Karacay Habibe , McBride William , Cardillo Thomas M. , Hansen Hans J. , Qu Zhengxing , Horak Ivan D. , Goldenberg David M.
Published: March 2006

Purpose: To characterize a novel trivalent bispecific fusion protein and evaluate its potential utility for pretargeted delivery of radionuclides to tumors.

Experimental Design: hBS14, a recombinant fusion protein that binds bispecifically to carcinoembryonic antigen (CEA) and the hapten, histamine-succinyl-glycine (HSG), was produced by transgenic myeloma cells and purified to near homogeneity in a single step using a novel HSG-based affinity chromatography system. Biochemical characterization included size-exclusion high-performance liquid chromatography (SE-HPLC), SDS-PAGE, and isoelectric focusing. Functional characterization was provided by BIAcore and SE-HPLC. The efficacy of hBS14 for tumor pretargeting was evaluated in CEA-expressing GW-39 human colon tumor–bearing nude mice using a bivalent HSG hapten (IMP-241) labeled with 111In.

Results: Biochemical analysis showed that single-step affinity chromatography provided highly purified material. SE-HPLC shows a single protein peak consistent with the predicted molecular size of hBS14. SDS-PAGE analysis shows only two polypeptide bands, which are consistent with the calculated molecular weights of the hBS14 polypeptides. BIAcore showed the bispecific binding properties and suggested that hBS14 possesses two functional CEA-binding sites. This was supported by SE-HPLC immunoreactivity experiments. All of the data suggest that the structure of hBS14 is an 80 kDa heterodimer with one HSG and two CEA binding sites. Pretargeting experiments in the mouse model showed high uptake of radiopeptide in the tumor, with favorable tumor-to-nontumor ratios as early as 3 hours postinjection.

Conclusions: The results indicate that hBS14 is an attractive candidate for use in a variety of pretargeting applications, particularly tumor therapy with radionuclides and drugs.
Development of Tumor Targeting Bioprobes (111In-Chimeric L6 Monoclonal Antibody Nanoparticles) for Alternating Magnetic Field Cancer Therapy
Authors: DeNardo Sally J. , DeNardo Gerald L. , Miers Laird A. , Natarajan Arutselvan , Foreman Alan R. , Gruettner Cordula , Adamson Grete N. , Ivkov Robert
Published: March 2006

Objectives: 111In-chimeric L6 (ChL6) monoclonal antibody (mAb)–linked iron oxide nanoparticle (bioprobes) pharmacokinetics, tumor uptake, and the therapeutic effect of inductively heating these bioprobes by externally applied alternating magnetic field (AMF) were studied in athymic mice bearing human breast cancer HBT 3477 xenografts. Tumor cell radioimmunotargeting of the bioprobes and therapeutic and toxic responses were determined.

Methods: Using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide HCl, 111In-7,10-tetra-azacyclododecane-N, N′,N″,N‴-tetraacetic acid-ChL6 was conjugated to the carboxylated polyethylene glycol on dextran-coated iron oxide 20 nm particles, one to two mAbs per nanoparticle. After magnetic purification and sterile filtration, pharmacokinetics, histopathology, and AMF/bioprobe therapy were done using 111In-ChL6 bioprobe doses (20 ng/2.2 mg ChL6/ bioprobe), i.v. with 50 μg ChL6 in athymic mice bearing HBT 3477; a 153 kHz AMF was given 72 hours postinjection for therapy with amplitudes of 1,300, 1,000, or 700 Oe. Weights, blood counts, and tumor size were monitored and compared with control mice receiving nothing, or AMF or bioprobes alone.

Results: 111In-ChL6 bioprobe binding in vitro to HBT 3477 cells was 50% to 70% of that of 111In-ChL6. At 48 hours, tumor, lung, kidney, and marrow uptakes of the 111In-ChL6 bioprobes were not different from that observed in prior studies of 111In-ChL6. Significant therapeutic responses from AMF/bioprobe therapy were shown with up to eight times longer mean time to quintuple tumor volume with therapy compared with no treatment (P = 0.0013). Toxicity was only seen in the 1,300 Oe AMF cohort, with 4 of 12 immediate deaths and skin erythema. Electron micrographs showed bioprobes on the surfaces of the HBT 3477 cells of excised tumors and tumor necrosis 24 hours after AMF/bioprobe therapy.

Conclusion: This study shows that mAb-conjugated nanoparticles (bioprobes), when given i.v., escape into the extravascular space and bind to cancer cell membrane antigen, so that bioprobes can be used in concert with externally applied AMF to deliver thermoablative cancer therapy.
Identification of magnetic resonance detectable metabolic changes associated with inhibition of phosphoinositide 3-kinase signaling in human breast cancer cells
Authors: Beloueche-Babari Mounia , Jackson L. Elizabeth , Al-Saffar Nada M.S. , Eccles Suzanne A. , Raynaud Florence I. , Workman Paul , Leach Martin O. , Ronen Sabrina M.
Published: March 2006

Phosphoinositide 3-kinase (PI3K) is an attractive target for novel mechanism-based anticancer treatment. We used magnetic resonance (MR) spectroscopy (MRS) to detect biomarkers of PI3K signaling inhibition in human breast cancer cells. MDA-MB-231, MCF-7, and Hs578T cells were treated with the prototype PI3K inhibitor LY294002, and the 31P MR spectra of cell extracts were monitored. In every case, LY294002 treatment was associated with a significant decrease in phosphocholine levels by up to 2-fold (P < 0.05). In addition, a significant increase in glycerophosphocholine levels by up to 5-fold was also observed (P ≤ 0.05), whereas the content of glycerophosphoethanolamine, when detectable, did not change significantly. Nucleotide triphosphate levels did not change significantly in MCF-7 and MDA-MB-231 cells but decreased by ∼1.3-fold in Hs578T cells (P = 0.01). The changes in phosphocholine and glycerophosphocholine levels seen in cell extracts were also detectable in the 31P MR spectra of intact MDA-MB-231 cells following exposure to LY294002. When treated with another PI3K inhibitor, wortmannin, MDA-MB-231 cells also showed a significant decrease in phosphocholine content by ∼1.25-fold relative to the control (P < 0.05), whereas the levels of the remaining metabolites did not change significantly. Our results indicate that PI3K inhibition in human breast cancer cells by LY294002 and wortmannin is associated with a decrease in phosphocholine levels. [Mol Cancer Ther 2006;5(1):187–96]
Down-regulation of DNA mismatch repair proteins in human and murine tumor spheroids: implications for multicellular resistance to alkylating agents
Authors: Francia Giulio , Green Shane K. , Bocci Guido , Man Shan , Emmenegger Urban , Ebos John M.L. , Weinerman Adina , Shaked Yuval , Kerbel Robert S.
Published: March 2006

Similar to other anticancer agents, intrinsic or acquired resistance to DNA-damaging chemotherapeutics is a major obstacle for cancer therapy. Current strategies aimed at overcoming this problem are mostly based on the premise that tumor cells acquire heritable genetic mutations that contribute to drug resistance. Here, we present evidence for an epigenetic, tumor cell adhesion–mediated, and reversible form of drug resistance that is associated with a reduction of DNA mismatch repair proteins PMS2 and/or MLH1 as well as other members of this DNA repair process. Growth of human breast cancer, human melanoma, and murine EMT-6 breast cancer cell lines as multicellular spheroids in vitro, which is associated with increased resistance to many chemotherapeutic drugs, including alkylating agents, is shown to lead to a reproducible down-regulation of PMS2, MLH1, or, in some cases, both as well as MHS6, MSH3, and MSH2. The observed down-regulation is in part reversible by treatment of tumor spheroids with the DNA-demethylating agent, 5-azacytidine. Thus, treatment of EMT-6 mouse mammary carcinoma spheroids with 5-azacytidine resulted in reduced and/or disrupted cell-cell adhesion, which in turn sensitized tumor spheroids to cisplatin-mediated killing in vitro. Our results suggest that antiadhesive agents might sensitize tumor spheroids to alkylating agents in part by reversing or preventing reduced DNA mismatch repair activity and that the chemosensitization properties of 5-azacytidine may conceivably reflect its role as a potential antiadhesive agent as well as reversal agent for MLH1 gene silencing in human tumors.
YC-1 suppresses constitutive nuclear factor-κB activation and induces apoptosis in human prostate cancer cells
Authors: Huang Yao-Ting , Pan Shiow-Lin , Guh Jih-Hwa , Chang Ya-Ling , Lee Fang-Yu , Kuo Sheng-Chu , Teng Che-Ming
Published: March 2006

Although the indazole compound, YC-1, is reported to exert anticancer activities in several cancer cell types, its target and mechanism of action have not been well explored. The objectives of this study were to ascertain whether YC-1 directly induces apoptosis in prostate cancer cells and to explore the mechanism(s) whereby YC-1 causes cell death. Hormone-refractory metastatic human prostate cancer PC-3 cells were selected for this study. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay indicated that YC-1 suppresses growth of PC-3 cells in a concentration-dependent and time-dependent manner. Apoptosis was determined using 4′,6-diamidino-2-phenylindole staining, and cell cycle progression was examined by FACScan flow cytometry. YC-1 treatment showed chromatin condensation and increased the percentage of PC-3 cells in the hypodiploid sub-G0-G1 phase, indicative of apoptosis. Additionally, exposure to YC-1 was found to induce activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase. Translocation and activation of nuclear factor-κB (NF-κB) were determined by immunofluorescent staining and ELISA, respectively. The results showed that YC-1 abolished constitutive nuclear translocation and activation of NF-κB/p65. Furthermore, inhibition of inhibitor of κBα (IκBα) phosphorylation and accumulation of IκBα were observed. The antitumor effects of YC-1 were evaluated by measuring the growth of tumor xenografts in YC-1-treated severe combined immunodeficient mice. The volumes of PC-3 tumors produced in severe combined immunodeficient mice were observed to decline significantly after treatment with YC-1 compared with vehicle controls. We concluded that the antitumor effects of YC-1 in PC-3 cells include the induction of apoptosis and the suppression of NF-κB activation. Given these unique actions, further investigations of the effects of YC-1 against hormone-refractory prostate cancer are warranted.
Modulation of chemotherapy resistance in regional therapy: a novel therapeutic approach to advanced extremity melanoma using intra-arterial temozolomide in combination with systemicO6-benzylguanine
Authors: Ueno Tomio , Ko Sae Hee , Grubbs Elizabeth , Yoshimoto Yasunori , Augustine Christi , Abdel-Wahab Zeinab , Cheng Tsung-Yen , Abdel-Wahab Omar I. , Pruitt Scott K. , Friedman Henry S. , Tyler Douglas S.
Published: March 2006

This study investigated whether the therapeutic index of regional melanoma therapy using parenteral temozolomide could be improved by chemomodulation with O6-benzylguanine (O6BG), an inhibitor of the DNA repair enzyme O6-alkylguanine-DNA alkyltransferase (AGT). Using a nude rat s.c. human melanoma xenograft model of the extremity, tumors were analyzed for AGT level 2 to 3 hours after the i.p. injection of 3.5 to 70.0 mg/kg O6BG to inhibit AGT activity. Survival studies were conducted using animals that were treated with a 15-minute isolated limb infusion with 10% DMSO in PBS (control), temozolomide alone, or temozolomide in conjunction with single or multiple doses of i.p. O6BG. Tumor volume and toxicity level were monitored every other day. Administration of 3.5 mg/kg O6BG depleted tumor AGT activity by 93.5% (P < 0.01). Groups treated with regional temozolomide alone (350 mg/kg), systemic temozolomide with O6BG, or vehicle combined with O6BG showed no significant tumor responses compared with controls. Whereas use of regional temozolomide alone at a higher dose (750 mg/kg) showed some degree of tumor response, regional temozolomide given in conjunction with multiple dosages of O6BG showed a marked (P < 0.01) reduction in tumor growth with minimal toxicity. Our findings suggest that AGT modulation by the administration of O6BG in combination with temozolomide regional chemotherapy leads to a significant improvement in melanoma antitumor responses. Clinical trials using chemotherapy modulation may improve response rates in future regional infusion and perfusion drug trials. [Mol Cancer Ther 2006;5(3):732–8]