bluuebunny/crossref_metadata_2025 huggingface dataset:
Proliferation and Apoptosis as Markers of Benefit in Neoadjuvant Endocrine Therapy of Breast Cancer
Authors: Dowsett Mitch , Smith Ian E. , Ebbs Steve R. , Dixon J. Michael , Skene Anthony , Griffith Clive , Boeddinghaus Irene , Salter Janine , Detre Simone , Hills Margaret , Ashley Susan , Francis Stephen , Walsh Geraldine , A'Hern Roger
Published: March 2006

The study of changes in proliferation as a marker of treatment benefit during presurgical endocrine treatment of breast cancer has become increasingly popular, particularly using the nuclear marker Ki67, and holds the potential for prioritizing new treatments for full clinical development. There are weakly significant relationships between Ki67 change and clinical response that differ according to data handling. In the neoadjuvant Immediate Preoperative Anastrozole, Tamoxifen, or Combined with Tamoxifen trial, suppression of Ki67 at both 2 and 12 weeks was greater with the aromatase inhibitor anastrozole than with either tamoxifen or the combination of anastrozole and tamoxifen. We report here that absolute values of Ki67 after 2 weeks were also significantly lower with anastrozole than with tamoxifen and the combination. This indicates that it may be possible to make such comparisons using surgical samples only. We argue that these changes in proliferation and concurrent changes in apoptosis may be expected to be more predictive of adjuvant benefit from endocrine therapy than clinical response.
Progesterone Receptor Loss Correlates with Human Epidermal Growth Factor Receptor 2 Overexpression in Estrogen Receptor–Positive Breast Cancer
Authors: Kim Hyun-Jung , Cui Xiaojiang , Hilsenbeck Susan G. , Lee Adrian V.
Published: March 2006

Response to endocrine therapy in breast cancer correlates with estrogen receptor (ER) and progesterone receptor (PR) status. It was originally hypothesized that the ability of PR to predict response to endocrine therapy was due to the fact that PR is an estrogen-regulated gene and that its levels represented a marker of functional ER activity. However, it is now known that loss of PR can occur via multiple mechanisms, many of which do not include ER function, e.g., hypermethylation of the PR promoter and loss of heterozygosity of the PR gene. We have shown that growth factor signaling pathways can directly down-regulate PR levels via the phosphatidylinositol 3′-kinase (PI3K)/Akt/mTOR pathway, and that this can occur independent of ER. For example, overexpression of myr-Akt in MCF-7 cells causes complete loss of PR protein and mRNA but does not reduce ER levels or activity, thus generating ER+/PR− MCF-7 cells. Therefore, the absence of PR may not simply reflect a lack of ER activity but rather may reflect hyperactive cross-talk between ER and growth factor signaling pathways. Consistent with this hypothesis, several recent clinical studies have found that ER+/PR− breast cancers overexpress human epidermal growth factor receptor (HER) 1 and HER2 compared with ER+/PR+ breast cancers. Although HER receptors can lower ER levels, one study showed that loss of PR correlated with high HER2 levels in a multivariate analysis. Furthermore, loss of PTEN, a negative regulator of the PI3K/Akt signaling pathway, has been shown to be associated with specific loss of PR and no change in ER levels. Given the well-recognized resistance of ER+/PR− breast cancer to antiestrogens, more studies are needed to better understand the etiology of ER+/PR− breast cancer, particularly the analysis of other growth factor receptors and their downstream signaling intermediates with respect to PR status.
Irinotecan Inactivation Is Modulated by Epigenetic Silencing ofUGT1A1in Colon Cancer
Authors: Gagnon Jean-François , Bernard Olivier , Villeneuve Lyne , Têtu Bernard , Guillemette Chantal
Published: March 2006

Purpose: Irinotecan is used in the first-line treatment of metastatic colorectal cancer. The UGT1A1-metabolizing enzyme, expressed in liver and colon, is primarily involved in the inactivation of its active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38). Herein, we explored the role of DNA methylation in the silencing of UGT1A1 gene expression in colon cancer and its influence on cellular SN-38 detoxification.

Experimental Design and Results: UGT1A1 mRNA was repressed in most primary tumors (41 of 50; 82%) and in three colon cancer cell lines (HCT-116, HCT-15, and COLO-320DM). Bisulfite sequencing of the UGT1A1 gene revealed the aberrant methylation of specific CpG islands in UGT1A1-negative cells. Conversely, hypomethylation was observed in HT-29, HT-115, and LOVO cells that overexpress UGT1A1. Direct methylation of the UGT1A1 promoter resulted in the complete repression of transcriptional activity. Treatment with demethylating and histone deacetylase inhibitor agents had the capacity to reverse aberrant hypermethylation and to restore UGT1A1 expression in hypermethylated UGT1A1-negative cells but not in hypomethylated cells. Loss of UGT1A1 methylation was further associated with an increase in UGT1A1 protein content and with an enhanced inactivation of SN-38 by 300% in HCT-116 cells.

Conclusions: We conclude that DNA methylation represses UGT1A1 expression in colon cancer and that this process may contribute to the level of tumoral inactivation of the anticancer agent SN-38 and potentially influence clinical response.
Intraperitoneal Immunotherapy for Metastatic Ovarian Carcinoma: Resistance of Intratumoral Collagen to Antibody Penetration
Authors: Choi Jaehwa , Credit Kimberly , Henderson Karla , Deverkadra Ravi , He Zhi , Wiig Helge , Vanpelt Heather , Flessner Michael F.
Published: March 2006

Purpose: Convective transport of macromolecules from the peritoneal cavity into tumor is determined by its hydraulic permeability and the pressure gradient. Previous studies showed that establishing a pressure gradient into the tumor failed to result in significant penetration. This study addresses the hypothesis that the extracellular matrix is the major resistance to the penetration of an i.p. injected antibody.

Experimental Design: Human ovarian tumors (SKOV-3 and OVCAR-3) were established in the abdominal wall of athymic rats. After anesthesia, the tumor serosal surface was treated for 2 hours with Krebs solution (control), collagenase (37.5 unit/mL), or hyaluronidase (10 unit/mL) followed by 3 hours of convective delivery of radiolabeled IgG. Transport of antibody into the tumor was measured with quantitative autoradiography along with the tumor interstitial pressure, concentration of collagen and hyaluronic acid, and IgG volume of distribution.

Results: Antibody was excluded from 42% to 53% of tumor extracellular volume. Exposure of tumors to hyaluronidase did not enhance IgG transport despite removal of 90% of the hyaluronan from the exposed tumor. In contrast, collagenase reduced collagen content, lowered tumor interstitial pressure, and markedly enhanced antibody penetration.

Conclusions: Reduction of collagen, but not hyaluronan, in the matrix of ovarian xenografts enhanced the transport of i.p. injected antibody. Although high interstitial pressure is a deterrent to convective transport of macromolecules into the tumor parenchyma, the structure of the interstitial matrix provides an inherent resistance, which must be overcome before effective delivery of an antibody.
Structural and Functional Features of the B-Cell Receptor in IgG-Positive Chronic Lymphocytic Leukemia
Authors: Potter Kathleen N. , Mockridge C. Ian , Neville Louise , Wheatley Isla , Schenk Michael , Orchard Jennifer , Duncombe Andrew S. , Packham Graham , Stevenson Freda K.
Published: March 2006

Purpose: To determine the origin and relationship of the rare IgG+ variant of chronic lymphocytic leukemia (CLL) to the two common IgM+IgD+ subsets that are distinguished by expression of unmutated or mutated VH genes, with the former having a worse prognosis.

Experimental Design: IgG+ CLL cells were characterized using phenotypic, functional, and immunogenetic analyses.

Results: IgG+ CLL was phenotypically similar to mutated IgM+IgD+ CLL (M-CLL) and variably expressed CD38 (4 of 14). ZAP-70, a tyrosine kinase preferentially expressed in unmutated CLL, was found in only 2 of 14 cases. The ability to signal via surface IgM (sIgM) varies between the main subsets of CLL and is associated with expression of ZAP-70. In IgG+ CLL, 9 of 14 responded to engagement of sIgG with no apparent requirement for expression of CD38 or ZAP-70. However, signal capacity correlated with intensity of sIgG expression. Most switched immunoglobulin variable region genes were somatically mutated without intraclonal variation, and no case expressed activation-induced cytidine deaminase. Derivation from a postgerminal center B cell is, therefore, likely, and a relationship with M-CLL is suggested. This is supported by a shared biased usage of the V4-34 gene. Similar bias in normal B cells developed with age, providing an expanded population for transforming events. However, conserved sequences detected in the CDR3 of V4-34-encoded γ chains were not found M-CLL, indicating no direct path of isotype switch from M-CLL.

Conclusion: IgG+ CLL is likely to arise from an age-related expanded pool of B cells, on a path parallel to M-CLL, and perhaps with a similar clinical course.
Lomeguatrib, a Potent Inhibitor of O6-Alkylguanine-DNA-Alkyltransferase: Phase I Safety, Pharmacodynamic, and Pharmacokinetic Trial and Evaluation in Combination with Temozolomide in Patients with Advanced Solid Tumors
Authors: Ranson Malcolm , Middleton Mark R. , Bridgewater John , Lee Siow Ming , Dawson Martin , Jowle Debra , Halbert Gavin , Waller Sue , McGrath Helen , Gumbrell Lindsey , McElhinney R. Stanley , Donnelly Dorothy , McMurry T. Brian H. , Margison Geoffrey P.
Published: March 2006

Purpose: A major mechanism of resistance to temozolomide involves the DNA repair protein O6-alkylguanine-DNA-alkyltransferase (ATase). The main aims of this phase I trial were to determine an ATase-depleting dose (ADD) of lomeguatrib, a potent pseudosubstrate inhibitor, and to define a suitable dose of temozolomide to be used in combination with lomeguatrib in patients with advanced cancer.

Experimental Design: Lomeguatrib was administered at dose levels of 10 to 40 mg/m2 days 1 to 5, as a single agent, and also in combination with temozolomide. Once the ADD of lomeguatrib was identified, the dose of temozolomide in combination was increased, in successive patient cohorts, from 50 to 175 mg/m2 on days 1 to 5 of a 28-day cycle to define the maximal tolerated dose and dose-limiting toxicity of the combination.

Results: Thirty-eight patients with advanced solid tumors were enrolled. More than 95% ATase depletion within 4 hours of the first dose was achieved in peripheral blood mononuclear cells at lomeguatrib doses of ≥10 mg/m2/d i.v. or ≥20 mg/m2/d orally, and tumor biopsies showed ≥92% ATase depletion. At the ADD of lomeguatrib i.v., the maximal tolerated dose of temozolomide in combination was 150 mg/m2 days 1 to 5. The dose limiting toxicity of the combination of lomeguatrib and temozolomide was myelosuppression. The toxicity of lomeguatrib alone was minimal. In 23 patients with measurable disease, one complete response was seen and 12 patients had stable disease for at least 3 months.

Conclusion: This first administration of lomeguatrib to man successfully established an oral ADD of lomeguatrib and identified a combination regimen with temozolomide suitable for future clinical evaluation.
Methods for Gene Expression Profiling in Clinical Trials of Adjuvant Breast Cancer Therapy
Authors: Paik Soonmyung
Published: March 2006

Although endocrine therapy is highly effective in the treatment of endocrine receptor–positive breast cancer, chemotherapy has been shown to provide clinical benefit when added to tamoxifen. However, baseline risk after tamoxifen treatment is so low, especially in patients who are axillary node negative, that significant overtreatment will result if chemotherapy is given to every patient. Robust prognostic and predictive markers need to be developed to identify those at high risk of treatment failure. Although comprehensive gene expression profiling methods do offer promise, they require fresh or frozen tumor samples. To take advantage of existing archived tissue blocks with clinical follow-up collected from finished clinical trials, such as National Surgical Adjuvant Breast and Bowel Project trials B-20 and B-14, technologies that allow interrogation of archived blocks for gene expression profiling need to be realized. Recent developments in gene expression profiling technologies are discussed with their implications in clinical management of endocrine receptor–positive breast cancer.
Mobilization of Bone Marrow Stem Cells by Granulocyte Colony-Stimulating Factor Ameliorates Radiation-Induced Damage to Salivary Glands
Authors: Lombaert Isabelle M.A. , Wierenga Pieter K. , Kok Tineke , Kampinga Harm H. , deHaan Gerald , Coppes Robert P.
Published: March 2006

Purpose: One of the major reasons for failure of radiotherapeutic cancer treatment is the limitation in dose that can be applied to the tumor because of coirradiation of the normal healthy tissue. Late radiation-induced damage reduces the quality of life of the patient and may even be life threatening. Replacement of the radiation-sterilized stem cells with unirradiated autologous stem cells may restore the tissue function. Here, we assessed the potential of granulocyte colony-stimulating factor (G-CSF)–mobilized bone marrow–derived cells (BMC) to regenerate and functionally restore irradiated salivary glands used as a model for normal tissue damage.

Experimental Design: Male-eGFP+ bone marrow chimeric female C57BL/6 mice were treated with G-CSF, 10 to 60 days after local salivary gland irradiation. Four months after irradiation, salivary gland morphology and flow rate were assessed.

Results: G-CSF treatment induced homing of large number of labeled BMCs to the submandibular glands after irradiation. These animals showed significant increased gland weight, number of acinar cells, and salivary flow rates. Donor cells expressed surface markers specific for hematopoietic or endothelial/mesenchymal cells. However, salivary gland acinar cells neither express the G-CSF receptor nor contained the GFP/Y chromosome donor cell label.

Conclusions: The results show that BMCs home to damaged salivary glands after mobilization and induce repair processes, which improve function and morphology. This process does not involve transdifferentiation of BMCs to salivary gland cells. Mobilization of BMCs could become a promising modality to ameliorate radiation-induced complications after radiotherapy.
Anastrozole as an Adjuvant Endocrine Treatment for Postmenopausal Patients with Breast Cancer: Emerging Data
Authors: Buzdar Aman U. , Cuzick Jack
Published: March 2006

The Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial compared the efficacy and safety of anastrozole versus tamoxifen versus the combination as initial adjuvant treatment for early breast cancer in over 9,000 postmenopausal women. Analyses at 33 and 47 months median follow-up showed that anastrozole significantly prolonged disease-free survival and time to recurrence and reduced the incidence of contralateral breast cancer compared with tamoxifen. Results of the completed treatment analysis at 68 months median follow-up confirmed the earlier findings, showing that the absolute difference in disease-free survival continued to increase beyond completion of treatment. Mature safety data from the ATAC trial show that, overall, anastrozole has a favorable safety profile compared with tamoxifen. In the absence of current data on further follow-up or the outcome of trials investigating proactive sequencing of endocrine therapies, we present a model based on several trials, including ATAC. This model suggests that using an aromatase inhibitor as initial adjuvant therapy is a better option than switching to an aromatase inhibitor after ≥2 years of tamoxifen. The relative toxicities of the three approved third-generation aromatase inhibitors, anastrozole, letrozole, and exemestane, are discussed. These data suggest that long-term safety profiles may differ between aromatase inhibitors, although comprehensive comparative data for letrozole and exemestane versus tamoxifen are lacking.
Tumor Epithelial Cell Matrix Metalloproteinase 9 Is a Target for Antimetastatic Therapy in Colorectal Cancer
Authors: Lubbe Wilhelm J. , Zhou Zengyi Y. , Fu Weili , Zuzga David , Schulz Stephanie , Fridman Rafael , Muschel Ruth J. , Waldman Scott A. , Pitari Giovanni M.
Published: March 2006

Background: The current paradigm suggests that matrix metalloproteinase 9 (MMP-9) expressed by stromal cells is a therapeutic target in human colorectal tumors which presumably regulates metastatic disease progression. Conversely, whereas cancer cells within those tumors may induce stromal cells to produce MMP-9 and may be targets for MMP-9 activity, they are not the source of MMP-9 underlying metastasis.

Methods: MMP-9 expression in matched colorectal tumors and normal adjacent mucosa from patients and human colon cancer cell lines was examined by real-time reverse transcription-PCR, laser capture microdissection, immunoelectron microscopy, and immunoblot analysis. The role of colon cancer cell MMP-9 in processes underlying metastasis was explored in vitro by examining degradation of extracellular matrix components by gelatin zymography and formation of locomotory organelles by cell spreading analysis and in vivo by quantifying hematogenous tumor cell seeding of mouse lungs.

Results: Primary colorectal tumors overexpress MMP-9 compared with matched normal adjacent mucosa. In contrast to the current paradigm, MMP-9 is expressed equally by cancer and stromal cells within human colon tumors. Cancer cell MMP-9 regulates metastatic behavior in vitro, including degradation of extracellular matrix components and formation of locomotory organelles. Moreover, this MMP-9 critically regulates hematogenous seeding of mouse lungs by human colon cancer cells in vivo.

Conclusions: These observations reveal that MMP-9 produced by human colon cancer, rather than stromal, cells is central to processes underlying metastasis. They underscore the previously unrecognized potential of specifically targeting tumor cell MMP-9 in interventional strategies to reduce mortality from metastatic colorectal cancer.
Management of Central Nervous System Lymphomas Using Monoclonal Antibodies: Challenges and Opportunities
Authors: Wong Eric T.
Published: March 2006

Monoclonal antibodies (mAb) may change the management of central nervous system (CNS) lymphomas. This is due to the fact that traditional chemotherapies lack specificity for B-lymphoma cells and blood-brain barrier prevents adequate chemotherapy dosing in the CNS without significant systemic side effects. But in the past 5 years, the emergence of mAbs against specific receptors on B-lymphoma cells, either as a single agent or in combination with cytotoxic chemotherapies, may offer a better therapeutic index than conventional chemotherapies. The advantages of mAbs include high affinity to targets on lymphoma cells, their lack of pharmacodynamic or pharmacokinetic interactions with other drugs, and a potential for a synergistic therapeutic response when combined with conventional chemotherapies. Our review summarizes the biological behaviors of CNS lymphomas and the challenges and opportunities in using mAbs for CNS lymphomas.
Does Paclitaxel (Taxol) Given after 111In-Labeled Monoclonal Antibodies Increase Tumor-Cumulated Activity in Epithelial Cancers?
Authors: Miers Laird , Lamborn Kathleen , Yuan Aina , Richman Carol , Natarajan Arutselvan , DeNardo Sally , DeNardo Gerald
Published: March 2006

Purpose: Paclitaxel synergized radiolabeled monoclonal antibodies, enhancing therapeutic effect in studies in mice with human xenografts. Paclitaxel was also observed to increase tumor uptake in imaging studies of 111In-DOTA-Gly3Phe-m170 in patients with breast and prostate cancers. Further evaluations of tissue-cumulated activities, therapeutic indices, and pharmacokinetics were done using data for patients with breast and prostate cancer and for mice with human breast cancer xenografts.

Experimental Design: In radioimmunotherapy trials, 12 patients with breast or prostate cancer were given two imaging doses (5 mCi each) of 111In-DOTA-Gly3Phe-m170 1 week apart. Five of these patients were given a single dose of paclitaxel i.v. (75 mg/m2) 2 days after the second dose of 111In. In a subsequent study, athymic mice with human breast cancer xenografts were given 111In-DOTA-Gly3Phe-ChL6 alone, or in combination with daily paclitaxel i.p. (300 μg) one or more times. Pharmacokinetics were studied for at least 6 days in patients and 5 days in mice. Cumulated activities were determined for tumors and normal tissues.

Results: Tumor-cumulated activity for every patient in the paclitaxel-treated group increased for the second dose of 111In-DOTA-Gly3Phe-m170. The median ratio of cumulated activities in tumors for imaging dose 2 to those for dose 1 was 1.0 (0.8-1.3) in patients that were not given paclitaxel and 1.3 (1.2-1.4) in patients given paclitaxel. Normal tissue-cumulated activities were not different for the two doses. Mice given paclitaxel 1 day after 111In-DOTA-Gly3Phe-ChL6 also showed an increase in tumor-cumulated activity, 22.9 (± 1.3) versus 19.4 (± 3.3) μCi h/g/μCi (P = 0.05). Cumulated activities of normal tissues were similar for all groups of mice.

Conclusions: Paclitaxel given 1 to 2 days after 111In-DOTA-Gly3Phe-monoclonal antibody increased the tumor-cumulated activity in patients and in mice with epithelial cancers and did not alter cumulated activities in normal tissues.
Preliminary Results of the Safety of Immunotherapy with Gemtuzumab Ozogamicin following Reduced Intensity Allogeneic Stem Cell Transplant in Children with CD33+ Acute Myeloid Leukemia
Authors: Roman Elizabeth , Cooney Erin , Harrison Lauren , Militano Olga , Wolownik Karen , Hawks Ria , Foley Sandi , Satwani Prakash , Unal Elif , Bhatia Monica , Bradley Brigid , Del Toro Gustavo , George Diane , Garvin James , van de Ven Carmella , Cairo Mitchell S.
Published: March 2006

Purpose: Myeloablative allogeneic stem cell transplantation (SCT) has been successful in the treatment of childhood acute myeloid leukemia (AML), but may be associated with significant toxicity and recurrent disease. Reduced-intensity allogeneic SCT may offer a less toxic approach to patients with AML. Targeted immunotherapy with gemtuzumab ozogamicin has been shown to be safe, well tolerated in children, and, as a single agent, gemtuzumab ozogamicin has induced responses in 30% of patients with recurrent CD33+ AML. There are no safety data with gemtuzumab ozogamicin post allogeneic SCT in children. Therefore, we explored the feasibility and toxicity of targeted immunotherapy following reduced-intensity allogeneic SCT in children with CD33+ AML.

Experimental Design: Eight patients with CD33+ AML received a reduced-intensity allogeneic SCT following fludarabine 30 mg/m2 for 6 days and busulfan 3.2 mg/kg (<4 years, 4 mg/kg/d) for 2 days. Donor sources included six 6/6 HLA-matched related peripheral blood stem cells, one 6/6 sibling cord blood, and one 4/6 unrelated cord blood.

Results: Day 30 and day 60 donor chimerisms in seven of eight evaluable patients were 96 ± 2% (n = 7) and 94 ± 3% (n = 6), respectively. Five of six patients (too early for one patient) received two doses of gemtuzumab ozogamicin and one patient received only one dose. After each dose, all patients developed grade 4 neutropenia, with recovery on median days 16 and 13, respectively, after dose 1 and dose 2. Grade 4 thrombocytopenia was only observed in 2 of 11 gemtuzumab ozogamicin courses. No patients have developed dose-limiting toxicity secondary to gemtuzumab ozogamicin.

Conclusions: The administration of gemtuzumab ozogamicin post reduced-intensity allogeneic SCT in children with average risk AML is feasible and well tolerated with minimal toxicity. The maximal tolerated dose has yet to be determined for gemtuzumab ozogamicin post reduced-intensity allogeneic SCT in children with CD33+ AML. Additional studies in a larger group of patients will be required to adequately assess the safety of this approach.
Enhanced Efficacy of Radioimmunotherapy with 90Y-CHX-A″-DTPA-hu3S193 by Inhibition of Epidermal Growth Factor Receptor (EGFR) Signaling with EGFR Tyrosine Kinase Inhibitor AG1478
Authors: Lee Fook T. , Mountain Angela J. , Kelly Marcus P. , Hall Cathrine , Rigopoulos Angela , Johns Terrance G. , Smyth Fiona E. , Brechbiel Martin W. , Nice Edouard C. , Burgess Antony W. , Scott Andrew M.
Published: March 2006

Purpose: Monoclonal antibodies and tyrosine kinase inhibitors specific for the epidermal growth factor receptor (EGFR) have been shown to enhance the effect of external beam radiation on EGFR-positive tumors. The effect of EGFR signaling abrogation by EGFR tyrosine kinase inhibitor on the efficacy of radioimmunotherapy has not been reported previously. This study investigated the effect of EGFR tyrosine kinase inhibition on the efficacy of radioimmunotherapy in a human cancer xenograft model.

Experimental Design: The humanized anti–Lewis Y antibody hu3S193 and the EGFR tyrosine kinase inhibitor AG1478 were studied. BALB/c nude mice were engrafted with A431 squamous carcinoma cells. Initial biodistribution properties of the 90Y-CHX-A″-DTPA-hu3S193 were evaluated in this model. In therapy experiments, cohorts of four to five xenografted mice were treated with saline as placebo, 0.4 mg AG1478 i.p. (six doses over 2 weeks), single i.v. injections of unlabeled hu3S193, or 90Y-CHX-A″-DTPA-hu3S193 (12.5, 25, 50, or 100 μCi). The combination of 0.4 mg AG1478 i.p. and 25 μCi 90Y-CHX-A″-DTPA-hu3S193 i.v. was subsequently evaluated in the A431 model.

Results: 90Y-CHX-A″-DTPA-hu3S193 retained excellent immunoreactivity after radiolabeling. The biodistribution study showed excellent uptake in tumor (90.33 ± 38.84%ID/g) peaking at 24 to 72 hours after injection and with prolonged retention. 90Y-CHX-A″-DTPA-hu3S193 significantly inhibited A431 xenograft growth at 25, 50, and 100 μCi doses. The combination of 0.4 mg AG1478 with a single dose of 25 μCi 90Y-CHX-A″-DTPA-hu3S193 resulted in a significant enhancement of efficacy compared with either agent alone (P = 0.013).

Conclusions: The efficacy of radioimmunotherapy with 90Y-CHX-A″-DTPA-hu3S193 is significantly enhanced by EGFR tyrosine kinase inhibitor AG1478. Further investigations of dosing regimens using EGFR tyrosine kinase inhibitors and radioimmunotherapy in the treatment of EGFR expressing tumors are warranted.
Radioimmunotherapy of Prostate Cancer Using 90Y- and 177Lu-Labeled J591 Monoclonal Antibodies: Effect of Multiple Treatments on Myelotoxicity
Authors: Vallabhajosula Shankar , Goldsmith Stanley J. , Kostakoglu Lale , Milowsky Mathew I. , Nanus David M. , Bander Neil H.
Published: March 2006

Purpose: Bone marrow is the dose-limiting organ in radioimmunotherapy. Fractionated dose regimens may decrease myelotoxicity and increase greater total administered dose. We have studied the effect of two or three treatments of 177Lu-J591 and 90Y-J591 monoclonal antibodies (mAb) on myelotoxicity.

Experimental Design: J591 is a deimmunized anti-PSMA mAb. Seven groups of patients with prostate cancer (n = 35) received 10 to 75 mCi/m2 of 177Lu-J591 and five additional groups (n = 28) received 5 to 20 mCi/m2 of 90Y-J591. Fifteen patients received two to three treatments of 177Lu-J591 (30, 45, or 60 mCi/m2) and four patients received two or three doses of 90Y-J591 (17.5 or 20 mCi/m2). Re-treatment consisted of patients receiving the same 177Lu or 90Y dose as their initial cycle. Time between treatments was 2 to 4 months.

Results: The single dose maximum tolerated dose was 70 mCi/m2 with 177Lu-J591 and 17.5 mCi/m2 with 90Y-J591. With a single dose of 177Lu, no severe toxicity was observed below 60 mCi/m2. With 177Lu, two doses of 45 or 60 mCi/m2, totaling 90 to 120 mCi/m2, proved to be quite toxic. Three doses of 30 mCi/m2 (total 90 mCi/m2), however, were well tolerated. With 90Y, four patients tolerated two to three doses of 17.5 or 20 mCi/m2. Thrombocytopenia increased at higher doses and after repeat treatments. At higher doses, the nadir was lower and the time to reach nadir was longer. Time for recovery of platelets seems related to the total dose.

Conclusions: Multiple (two or three) administrations of 177Lu-J591 (30-60 mCi/m2) or 90Y-J591 (17.5 mCi/m2) over a 4- to 6-month period were tolerated by the patients with manageable thrombocytopenia. Although a single large dose may deliver optimal radiation dose to kill a larger fraction of tumor cells, fractionated therapy offers the advantage of lower myelotoxicity and prolonged tumor response. With 177Lu-J591, dose fractionation in combination with taxanes should be considered as an alternative approach to achieve optimal therapeutic efficacy in patients with prostate cancer.
Antiproliferative activity of angiotensin II receptor blocker through cross-talk between stromal and epithelial prostate cancer cells
Authors: Uemura Hiroji , Ishiguro Hitoshi , Nagashima Yoji , Sasaki Takeshi , Nakaigawa Noboru , Hasumi Hisashi , Kato Shingo , Kubota Yoshinobu
Published: March 2006

We showed previously that angiotensin II activated the proliferation of prostate cancer cells and that angiotensin II receptor blockers (ARB) could inhibit it. Here, we investigated whether angiotensin II exerts mitogenic effects on the cross-talk between stromal and cancer cells and whether an ARB can inhibit tumor growth through actions on stromal cells. Cell proliferation and interleukin-6 secretion of prostate stromal PrSC cells stimulated with angiotensin II, tumor necrosis factor-α, or epidermal growth factor were examined in the absence and presence of ARB. We examined the effect of ARB on mitogen-activated protein kinase (MAPK) phosphorylation of PrSC and PC-3 cells treated with conditioned medium of PrSC cells and determined the effect of ARB on tumor growth induced by paracrine factors from PrSC cells. Angiotensin II activated the cell proliferation and interleukin-6 secretion of PrSC cells, and ARB inhibited it. Angiotensin II, tumor necrosis factor-α, or epidermal growth factor induced MAPK phosphorylation in PrSC cells, and this phosphorylation was inhibited by ARB. Conditioned medium of PrSC cells with angiotensin II activated MAPK phosphorylation in PC-3 cells, and ARB-treated conditioned medium of PrSC cells inhibited it. The tumor growth and angiogenesis of a mixture of PC-3 with PrSC were inhibited by ARB administration, whereas those of PC-3 xenografts were not inhibited. ARB exerted an antiproliferative effect on prostate cancer through paracrine factors from stromal cells. Because prostate stromal cells are thought to be involved in the initiation and development of prostate cancer, the present data suggest the possibility that ARBs are a novel therapeutic class of agents for prostate cancer.
Genome-wide transcriptional analysis of carboplatin response in chemosensitive and chemoresistant ovarian cancer cells
Authors: Peters David , Freund John , Ochs Robert L.
Published: March 2006

We have recently described an ex vivo chemoresponse assay for determining chemosensitivity in primary cultures of human tumors. In this study, we have extended these experiments in an effort to correlate chemoresponse data with gene expression patterns at the level of transcription. Primary cultures of cells derived from ovarian carcinomas of individual patients (n = 6) were characterized using the ChemoFx assay and classified as either carboplatin sensitive (n = 3) or resistant (n = 3). Three representative cultures of cells from each individual tumor were then subjected to Affymetrix gene chip analysis (n = 18) using U95A human gene chip arrays. Data were analyzed using the dCHIP software package. We identified a significant number of genes whose expression patterns were altered between carboplatin chemosensitive and chemoresistant cells, in normal culture conditions and in the presence of carboplatin for either 2 or 72 hours. Among these differentially expressed genes, we found a significant proportion to be associated with apoptosis, cell-cell communication, cell adhesion, DNA repair, and cell proliferation. In general, the molecular phenotype displayed by chemoresistant cells was reflective of an extended life span in culture in the presence of carboplatin and the genes that define this phenotype are potential biomarkers for the prognostic management of ovarian cancer patients.
Inhibition of the phosphatidylinositol 3-kinase/Akt pathway sensitizes MDA-MB468 human breast cancer cells to cerulenin-induced apoptosis
Authors: Liu Xuesong , Shi Yan , Giranda Vincent L. , Luo Yan
Published: March 2006

Fatty acid synthase is overexpressed in cancer especially in tumors with a poor prognosis. The specific fatty acid synthase inhibitor cerulenin can induce apoptosis in cancer cells. Likewise, phosphatidylinositol 3-kinase (PI3K)/Akt kinase activities are elevated in primary tumors and cancer cell lines. Here, we tested whether inhibition of PI3K/Akt pathway would sensitize cancer cells to cerulenin-induced apoptosis. We show that LY294002, an inhibitor of PI3K, sensitized MDA-MB468 breast cancer cells to cerulenin-induced apoptosis. In MDA-MB468 cells, cerulenin- and LY294002-mediated apoptosis was associated with caspase-3 activation and the release of cytochrome c from mitochondria to cytosol. In addition, we observed additional species of Bak in mitochondria, suggesting a possible Bak activation. Treatment of cells with cerulenin and LY294002 down-regulated the protein levels of X chromosome-linked inhibitor of apoptosis (XIAP), cellular inhibitor of apoptosis 1 (cIAP-1), and Akt, whereas the levels of mitogen-activated protein/extracellular signal-regulated kinase kinase and other antiapoptotic Bcl-2 family proteins (Bcl-2 and Bcl-xl) did not change. Interestingly, the nonspecific caspase inhibitor, z-VAD-FMK, inhibited the down-regulation of Akt, XIAP, and cIAP-1 in cerulenin- and LY294002-treated cells. In conclusion, these studies show that inhibition of PI3K can sensitize cerulenin-induced apoptosis in MBA-MB468 breast cancer cells via activation of caspases, down-regulation of antiapoptotic proteins, such as XIAP, cIAP-1 and Akt, and possibly, activation of Bak in mitochondria. [Mol Cancer Ther 2006;5(3):494–501]
The anticancer activity of the fungal metabolite terrecyclic acid A is associated with modulation of multiple cellular stress response pathways
Authors: Turbyville Thomas J. , Wijeratne E.M. Kithsiri , Whitesell Luke , Gunatilaka A.A. Leslie
Published: March 2006

Tumors are dependent on cellular stress responses, in particular the heat shock response, for survival in their hypoxic, acidotic, and nutrient-deprived microenvironments. Using cell-based reporter assays, we have identified terrecyclic acid A (TCA) from Aspergillus terreus, a fungus inhabiting the rhizosphere of Opuntia versicolor of the Sonoran desert, as a small-molecule inducer of the heat shock response that shows anticancer activity. Further characterization suggested that TCA also affects oxidative and inflammatory cellular stress response pathways. The presence of an α-methylene ketone moiety suggested that TCA may form adducts with sulfhydryl groups of proteins. Reaction with labile intracellular cysteines was supported by our finding that the glutathione precursor N-acetyl-cysteine protected tumor cells from the cytotoxic effects of TCA whereas the glutathione-depleting agent buthionine sulfoximine enhanced its activity. Related sesquiterpenes have been shown to increase levels of reactive oxygen species (ROS) and to inhibit nuclear factor κB (NF-κB) transcriptional activity. To assess whether TCA could have similar activities, we used a ROS-sensitive dye and flow cytometry to show that TCA does indeed increase ROS levels in 3LL cells. When tested in cells carrying NF-κB reporter constructs, TCA also exhibited concentration-dependent inhibition of cytokine-induced NF-κB transcriptional activity. These findings suggest that TCA modulates multiple stress pathways—the oxidative, heat shock, and inflammatory responses—in tumor cells that promote their survival. Small-molecule natural products such as TCA may serve as useful probes for understanding the relationships between these pathways, potentially providing leads for the design of novel and effective anticancer drugs.
A novel antisense oligonucleotide inhibiting several antiapoptotic Bcl-2 family members induces apoptosis and enhances chemosensitivity in androgen-independent human prostate cancer PC3 cells
Authors: Yamanaka Kazuki , Rocchi Palma , Miyake Hideaki , Fazli Ladan , Vessella Bob , Zangemeister-Wittke Uwe , Gleave Martin E.
Published: March 2006

Bcl-2 and Bcl-xL are associated with treatment resistance and progression in many cancers, including prostate cancer. The objective of this study was to determine whether a novel bispecific antisense oligonucleotide targeting both Bcl-2 and Bcl-xL induces apoptosis and enhances chemosensitivity in androgen-independent PC3 prostate cancer cells. An antisense oligonucleotide with complete sequence identity to Bcl-2 and three-base mismatches to Bcl-xL selected from five antisense oligonucleotides targeting various regions with high homology between Bcl-2 and Bcl-xL was found to be the most potent inhibitor of both Bcl-2 and Bcl-xL expression in PC3 cells. This selected Bcl-2/Bcl-xL bispecific antisense oligonucleotide reduced mRNA and protein levels in a dose-dependent manner, reducing Bcl-2 and Bcl-xL protein levels to 12% and 19%, respectively. Interestingly, Mcl-1 was down-regulated as well, although levels of Bax, Bad, or Bak were not altered after treatment with this bispecific antisense oligonucleotide. Indirect down-regulation of inhibitor of apoptosis (IAP) family, including XIAP, cIAP-1 and cIAP-2, via second mitochondria-derived activator of caspases was also observed after bispecific antisense oligonucleotide treatment. Executioner caspase-3, caspase-6, and caspase-7 were shown to be involved in apoptosis induced by bispecific antisense oligonucleotide. This Bcl-2/Bcl-xL bispecific antisense oligonucleotide also enhanced paclitaxel chemosensitivity in PC3 cells, reducing the IC50 of paclitaxel by >90%. These findings illustrate that combined suppression of antiapoptotic Bcl-2 family members using this antisense oligonucleotide could be an attractive strategy for inhibiting cancer progression through alteration of the apoptotic rheostat in androgen-independent prostate cancer.
Simultaneous targeting of the epidermal growth factor receptor and cyclooxygenase-2 pathways for pancreatic cancer therapy
Authors: Ali Shadan , El-Rayes Basil F. , Sarkar Fazlul H. , Philip Philip A.
Published: March 2006

The aims of this study were to determine the effects of (a) combining the epidermal growth factor receptor (EGFR) blocker (erlotinib) and the cyclooxygenase-2 inhibitor (celecoxib) on cell growth and apoptosis in human pancreatic cancer cell lines, (b) baseline EGFR expression on the potentiation of erlotinib-induced apoptosis by celecoxib, and (c) the effects of the combination on the expression of the COX-2, EGFR, HER-2/neu, and nuclear factor-κB (NF-κB). Baseline expression of EGFR was determined by Western blot analysis in five human pancreatic cancer cell lines. BxPC-3, PANC-1, and HPAC had high EGFR and MIAPaCa had low EGFR. Cells were grown in culture and treated with erlotinib (1 and 10 μmol/L), celecoxib (1 and 10 μmol/L), and the combination. Growth inhibition was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and apoptosis was assayed by ELISA. Reverse transcriptase-PCR was used to evaluate COX-2 and EGFR mRNA. EGFR, COX-2, and HER-2/neu expression was determined by Western immunoblotting. Electrophoretic mobility shift assay was used to evaluate NF-κB activation. Growth inhibition and apoptosis were significantly (P < 0.05) higher in BxPC-3, HPAC, and PANC-1 cells treated with celecoxib and erlotinib than cells treated with either celecoxib or erlotinib. However, no potentiation in growth inhibition or apoptosis was observed in the MIAPaCa cell line with low expression of the EGFR. Significant down-regulation of COX-2 and EGFR expression was observed in the BxPC-3 and HPAC cells treated with the combination of erlotinib (1 μmol/L) and celecoxib (10 μmol/L) compared with celecoxib- or erlotinib-treated cells. Celecoxib significantly down-regulated HER-2/neu expression in BxPC-3 and HPAC cell lines. Significant inhibition of NF-κB activation was observed in BxPC-3 and HPAC cell lines treated with erlotinib and celecoxib. (a) Celecoxib can potentiate erlotinib-induced growth inhibition and apoptosis in pancreatic cell lines, (b) high baseline EGFR expression is a predictor of this potentiation, and (c) the down-regulation of EGFR, COX-2, and HER-2/neu expression and NF-κB inactivation contributes to the potentiation of erlotinib by celecoxib. [Mol Cancer Ther 2005;4(12):1943–51]
Mammalian target of rapamycin inhibitors activate the AKT kinase in multiple myeloma cells by up-regulating the insulin-like growth factor receptor/insulin receptor substrate-1/phosphatidylinositol 3-kinase cascade
Authors: Shi Yijiang , Yan Huajun , Frost Patrick , Gera Joseph , Lichtenstein Alan
Published: March 2006

Mammalian target of rapamycin (mTOR) inhibitors, such as rapamycin and CCI-779, have shown preclinical potential as therapy for multiple myeloma. By inhibiting expression of cell cycle proteins, these agents induce G1 arrest. However, by also inhibiting an mTOR-dependent serine phosphorylation of insulin receptor substrate-1 (IRS-1), they may enhance insulin-like growth factor-I (IGF-I) signaling and downstream phosphatidylinositol 3-kinase (PI3K)/AKT activation. This may be a particular problem in multiple myeloma where IGF-I-induced activation of AKT is an important antiapoptotic cascade. We, therefore, studied AKT activation in multiple myeloma cells treated with mTOR inhibitors. Rapamycin enhanced basal AKT activity, AKT phosphorylation, and PI3K activity in multiple myeloma cells and prolonged activation of AKT induced by exogenous IGF-I. CCI-779, used in a xenograft model, also resulted in multiple myeloma cell AKT activation in vivo. Blockade of IGF-I receptor function prevented rapamycin's activation of AKT. Furthermore, rapamycin prevented serine phosphorylation of IRS-1, enhanced IRS-1 association with IGF-I receptors, and prevented IRS-1 degradation. Although similarly blocking IRS-1 degradation, proteasome inhibitors did not activate AKT. Thus, mTOR inhibitors activate PI3-K/AKT in multiple myeloma cells; activation depends on basal IGF-R signaling; and enhanced IRS-1/IGF-I receptor interactions secondary to inhibited IRS-1 serine phosphorylation may play a role in activation of the cascade. In cotreatment experiments, rapamycin inhibited myeloma cell apoptosis induced by PS-341. These results provide a caveat for future use of mTOR inhibitors in myeloma patients if they are to be combined with apoptosis-inducing agents.
Epigenetic modification of SOCS-1 differentially regulates STAT3 activation in response to interleukin-6 receptor and epidermal growth factor receptor signaling through JAK and/or MEK in head and neck squamous cell carcinomas
Authors: Lee Tin Lap , Yeh Jason , Van Waes Carter , Chen Zhong
Published: March 2006

Signal transducer and activator of transcription 3 (STAT3) has been reported to be activated by interleukin-6 receptor (IL-6R) or epidermal growth factor receptor (EGFR) in head and neck squamous cell carcinomas (HNSCC), which may have important implications for responsiveness to therapeutics targeted at EGFR, IL-6R, or intermediary kinases. Suppressor of cytokine signaling-1 (SOCS-1) has been implicated recently in the negative regulation of IL-6R/Janus-activated kinase (JAK)–mediated activation of STAT3, suggesting that SOCS-1 could affect alternative activation of STAT3 by EGFR, IL-6R, and associated kinases. We investigated whether epigenetic modification of SOCS-1 affects STAT3 activation in response to IL-6R-, EGFR-, JAK-, or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)–mediated signal activation. STAT3 was predominantly activated by IL-6R via Jak1/Jak2 in HNSCC lines UMSCC-9 and UMSCC-38 in association with transcriptional silencing of SOCS-1 by hypermethylation. In UMSCC-11A cells with unmethylated SOCS-1, STAT3 activation was regulated by both EGFR and IL-6R via a JAK-independent pathway involving MEK. Pharmacologic inhibitors of JAK and MEK and expression of SOCS-1 following demethylation or transient transfection inhibited STAT3 activation and cell proliferation and induced cell apoptosis in corresponding cell lines. Hypermethylation of SOCS-1 was found in about one-third of human HNSCC tissues, making it a potentially relevant marker for STAT-targeted therapy in HNSCC patients. We conclude that SOCS-1 methylation status can differentially affect STAT3 activation by IL-6R and EGFR through JAK or MEK in different HNSCC and response to pharmacologic antagonists. Identifying the potential factors and the regulatory pathways in STAT3 activation has important implications for the development and selection of molecularly targeted therapy in HNSCC. [Mol Cancer Ther 2006;5(1):8–19]
Butyric acid prodrugs are histone deacetylase inhibitors that show antineoplastic activity and radiosensitizing capacity in the treatment of malignant gliomas
Authors: Entin-Meer Michal , Rephaeli Ada , Yang Xiaodong , Nudelman Abraham , VandenBerg Scott R. , Haas-Kogan Daphne Adele
Published: March 2006

Histone modification has emerged as a promising approach to cancer therapy. We explored the efficacy of a novel class of histone deacetylase inhibitors in the treatment of malignant gliomas. Treatment of glioma cell lines with two butyric acid derivatives, pivaloylomethyl butyrate (AN-9) and butyroyloxymethyl butyrate (AN-1), induced hyperacetylation, increased p21Cip1 expression, inhibited proliferation, and enhanced apoptosis. Histone deacetylase inhibitor–induced apoptosis was mediated primarily by caspase-8. Treatment of cells with AN-1 or AN-9 for 24 hours before exposure to γ-irradiation potentiated further caspase-8 activity and resultant apoptosis. Clonogenic survival curves revealed marked reductions in cell renewal capacity of U251 MG cells exposed to combinations of AN-1 and radiation. Preliminary in vivo experiments using human glioma cell lines grown as xenografts in mouse flanks suggest in vivo efficacy of AN-9. The data suggest that novel butyric acid prodrugs provide a promising treatment strategy for malignant gliomas as single agents and in combination with radiation therapy. [Mol Cancer Ther 2005;4(12):1952-61]