[Medullar thoracic compression by tophaceous gout: presentation of a case and review of the literature]

INTRODUCTION

Spine involvement in gout is an extremely uncommon complication. Dorsalgia and quadriplegia are some manifestations that may occur, although these symptoms are seen more frequently in other more prevalent pathologies, such as spinal tumors.

CASE REPORT

We present an unusual case of thoracic spinal cord compression at T10-T11 level caused by the extradural deposit of tophaceous material in a 52-year-old woman with uncontrolled chronic tophaceous gout. In addition to intensive medical treatment, the patient required surgery (hemilaminectomy and spinal decompression) and subsequent rehabilitation. Overall and neurological evolution were satisfactory.

Abstract A091: Targeting the TGFb pathway with galunisertib, a TGFbRI SMI, promotes antitumor immunity leading to durable, complete responses, as monotherapy and in combination with checkpoint inhibition

TGFb signaling is known to play a central role in tumor biology, via inducing and/or enhancing tumor cell growth and differentiation, modulating the extracellular matrix in the stroma, inducing epithelial to mesenchymal transition, modulating angiogenesis, and inhibiting immune surveillance and anti-tumor immunity. Galunisertib is a pharmacological inhibitor of the TGFb pathway which acts by inhibiting signaling though TGFbRI. Galunisertib is currently being evaluated clinically in several Phase I and II studies; as a monotherapy, galunisertib has shown antitumor activity against a variety of tumors, including durable and long-term responses in patients with glioma.

To explore the impact of Galunisertib monotherapy on anti-tumor T cell immunity, we utilized murine tumor models. Treatment of mice with well-established 4T1-LP (poorly immunogenic 4T1 breast tumor engineered to express luciferase) implanted in the mammary fat pad resulted in strong dose-dependent anti-tumor activity with nearly 100% inhibition of tumor growth across doses during the dosing period, with complete tumor responses upon cessation of treatment in ~50% of animals at the highest dose tested; depletion studies demonstrated that regression of 4T1-LP was dependent on the presence of CD8+ T cells. Rechallenge of treated, tumor free mice resulted in complete rejection of 4T1-LP tumor cells but no rejection of EMT6-LM2 tumor cells, demonstrating the establishment of a durable response and immunological memory. Treatment of mice bearing established parental 4T1 tumors in the mammary fat pad resulted in no significant inhibition of tumor growth, indicating that the presence of a foreign antigen (i.e. LP), potentially enhanced the ability to regress the 4T1-LP derivative. Animals that rejected the immunogenic 4T1-LP tumors were able to also reject 4T1 parental cells upon rechallenge, suggesting the development of a secondary immune response via antigen spreading as a consequence of effective tumor targeting. In the CT26 murine colon carcinoma model, treatment of established tumors with galunisertib or anti-PD-L1 as monotherapies resulted in tumor growth inhibition compared to control of 75% and 86%, respectively (T/C values of 25% and 14%); complete responders were observed in about 20% of treated animals in both monotherapy groups. Combination of galunisertib with anti-PD-L1 resulted in an enhanced tumor growth inhibition of 98% (T/C value of ~2%), and a complete response rate of ~50%, suggesting at least additive activity with potential for synergy when targeting the TGFb and PD-1 pathways. Taken together, these data demonstrate the potential for galunisertib treatment to enhance the development of anti- tumor T cell immunity, which can be enhanced by combinations with immune check point inhibitors.

Citation Format: David Schaer, Yanxia Li, Stephen Castaneda, Ivan Inigo, David Surguladze, Xiaohong Xu, Desiree Nugent, Mary Murphy, Gerald Hall, Karim Benhadji, Susan Guba, Yiwen Li, Michael Kalos, Kyla Driscoll. Targeting the TGFb pathway with galunisertib, a TGFbRI SMI, promotes antitumor immunity leading to durable, complete responses, as monotherapy and in combination with checkpoint inhibition. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A091.

Painful legs and moving toes syndrome responsive to pregabalin

Report three cases of painful legs and moving toes (PLMT) syndrome responsive to pregabalin along with a review of its literature. Three patients with PLMT syndrome improved with pregabalin. The first and third patient reported improvement in pain scores, quality of life, and quality of sleep sustained over time. The second and third patient had near complete remission of toe movements, but pregabalin was discontinued in the second patient due to aggravation of leg edema. PLMT is a rare and debilitating disorder characterized by lower limb pain and involuntary toes or feet movements. Its pathophysiology remains unknown and its therapy refractory to most drugs, except for pregabalin, as shown in this case series. PLMT is a rare and incapacitating syndrome due to the lack of an effective pain therapy. We report three patients with PLMT who favorable responded to pregabalin. We propose pregabalin be considered in the management of PLMT.

Reduced expression of the androgen receptor by third generation of antisense shows antitumor activity in models of prostate cancer

The androgen receptor (AR) is a member of a unique class of transcription factors because it contains a ligand-binding domain that, when activated, results in nuclear translocation and the transcriptional activation of genes associated with prostate cancer development. Although androgen deprivation therapies are effective initially for the treatment of prostate cancer, the disease eventually relapses and progresses to castration-resistant prostate cancer (CRPC). Nonetheless, the AR still plays a critical role because late-stage investigational agents that deplete testosterone (abiraterone) or block ligand binding (MDV3100) can still control tumor growth in patients with CRPC. These findings indicate that downmodulation of AR expression may provide a complementary strategy for treating CRPC. In this article, we describe a novel, locked, nucleic acid-based antisense oligonucleotide, designated EZN-4176. When administered as a single agent, EZN-4176 specifically downmodulated AR mRNA and protein, and this was coordinated with inhibition of the growth of both androgen-sensitive and CRPC tumors in vitro as well as in animal models. The effect was specific because no effect on growth was observed with a control antisense oligonucleotide that does not recognize AR mRNA, nor on tumors derived from the PC3, AR-negative, tumor cell line. In addition, EZN-4176 reduced AR luciferase reporter activity in a CRPC model derived from C4-2b cells that were implanted intratibially, indicating that the molecule may control prostate cancer that has metastasized to the bone. These data, together with the continued dependency of CRPC on the AR signaling pathway, justify the ongoing phase I evaluation of EZN-4176 in patients with CRPC.

Abstract 5394: Dual inhibition of the androgen receptor by ligand blockade and antisense-mediated downregulation is associated with synergistic antitumor activity model of prostate cancer

Background: Although new agents to treat prostate cancer have recently been approved, and new investigational drugs (Abiraterone and MDV3100) that mediate hormone deprivation show promising data from late-stage clinical trials, these therapies typically extend overall survival up to 4 months in patients with advanced disease who have failed conventional androgen deprivation therapy. Hence, there continues to be great medical need. EZN-4176 is a novel LNA-based antisense oligonucleotide (EZN-4176) that down regulates androgen receptor (AR) expression. Previously, antitumor activity of EZN-4176 in multiple xenograft models including both androgen-sensitive and castrate-resistant tumors was shown. More importantly, a synergistic effect was also found when EZN-4176 was combined with MDV3100. Further exploration of the mechanistic underpinning of the effect was explored here. Methods: The mRNA, growth, luciferase activity, protein, and prostate specific antigen (PSA) were evaluated by qRT-PCR, MTT, SteadyGlo, western blot analysis, and ELISA assay, respectively. The effect of EZN-4176 on AR transcriptional activity was evaluated in cells stably express luciferase gene regulated by AR. In vivo, the effect of EZN-4176 on AR transcriptional activity was evaluated in a bone tumor model developed by intratibia injection of C4-2b-AR-luc cells. Results: Combination of EZN-4176 with MDV3100 resulted in a much improved inhibitory effect in colony formation assay in vitro. This effect was not associated with enhanced efficiency of AR mRNA down-modulation as treatment with EZN-4176 with or without MDV3100 showed similar effects on the level of AR mRNA. However, when AR transcriptional activity was examined, we found that the combined effect was greater than each agent alone. In C4-2b-AR-luc bone tumor model, EZN-4176 potently and specifically down-modulated AR-luciferase reporter activity. Further examinations of the anti-tumor effect in this model will help understand the potential of the combinatorial effect in a highly relevant disease model. Conclusions: Our preliminary data suggest that the synergistic anti-tumor effect of EZN-4176 in combination with MDV3100 is in part associated with much reduced transcriptional activity of AR. EZN-4176 alone or in combination with anti-androgens offers great potential in treating patients with advanced prostate cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5394. doi:10.1158/1538-7445.AM2011-5394

Complexin2 null mutation requires a 'second hit' for induction of phenotypic changes relevant to schizophrenia

Schizophrenia is a devastating disease that affects approximately 1% of the population across cultures. Its neurobiological underpinnings are still unknown. Accordingly, animal models of schizophrenia often lack construct validity. As concordance rate in monozygotic twins amounts to only 50%, environmental risk factors (e.g. neurotrauma, drug abuse, psychotrauma) likely act as necessary 'second hit' to trigger/drive the disease process in a genetically predisposed individual. Valid animal models would have to consider this genetic-environmental interaction. Based on this concept, we designed an experimental approach for modeling a schizophrenia-like phenotype in mice. As dysfunction in synaptic transmission plays a key role in schizophrenia, and complexin2 (CPLX2) gene expression is reduced in hippocampus of schizophrenic patients, we developed a mouse model with Cplx2 null mutation as genetic risk factor and a mild parietal neurotrauma, applied during puberty, as environmental 'second hit'. Several months after lesion, Cplx2 null mutants showed reduced pre-pulse inhibition, deficit of spatial learning and loss of inhibition after MK-801 challenge. These abnormalities were largely absent in lesioned wild-type mice and non-lesioned Cplx2 null mutants. Forced alternation in T-maze, object recognition, social interaction and elevated plus maze tests were unaltered in all groups. The previously reported mild motor phenotype of Cplx2 null mutants was accentuated upon lesion. MRI volumetrical analysis showed a decrease of hippocampal volume exclusively in lesioned Cplx2 null mutants. These findings provide suggestive evidence for the 'second hit' hypothesis of schizophrenia and may offer new tools for the development of advanced treatment strategies.

Abstract 601: In vitro and in vivo inhibition of β-catenin by two novel β-catenin RNA antagonists, EZN-3889 and 3892

Background: β-Catenin is a subunit of the cadherin protein complex and a key integral component in the Wnt signaling pathway. Therefore, it not only plays an important role in cell-cell adhesion but also in tumorgenesis. β-catenin is activated in most colon cancers due to either mutations in APC or activating mutations in β-catenin itself. Furthermore, activating β-catenin mutations have been found in a variety of other tumors such as melanomas, hepatocellular carcinomas, breast, and prostate cancer, whereas β-catenin is not activated in most normal tissues. Therefore, inhibition of β-catenin is likely to have therapeutic effects in many cancers. Unfortunately, because β-catenin is devoid of any enzymatic activity, the development of inhibitors of β-catenin has been slow. We present here both in vitro and in vivo evidence that the lack of specificity of small-molecule inhibitors may be overcome by two novel β-catenin LNA-based mRNA antagonists, EZN-3889 and EZN-3892. Material and Methods: In vitro, the ability of the compounds to inhibit mRNA, cell growth, and reporter gene were evaluated by qRT-PCR, MTS, and luciferase assays respectively, in multiple cell lines. In vivo, β-catenin mRNA down-modulation in liver and human tumors, which were grown on the flank of nude mice, was evaluated after intravenous administration of the compounds. Results: Without lipofection, we found that these two antagonists could specifically down modulate β-catenin mRNA and protein effectively in multiple cell lines with a long-lasting effect. Additionally, these two molecules effectively inhibited β-catenin transcriptional activity in SW480 colorectal and H1581 lung cancer cells stably expressing a TCF/LEF luciferase reporter gene, resulting in growth inhibition. Combination of EZN-3889 or 3892 with sulindac demonstrated improved activities in both growth and reporter assay. Moreover, EZN-3889 and 3892 inhibited the spontaneous growth of spheroids in SW480 culture and convert SW480 spheroids to monolayers. Preliminary data suggest that these spheroids were more tumorgenic than the monolayer cells. In mice, both molecules significantly down modulated β-catenin mRNA in the liver. Conclusions: Without lipofection, β-catenin antagonists potently and specifically inhibited β-catenin mRNA expression both in vitro and in vivo after intravenous injection. Target inhibition correlated with growth inhibition and phenotypical change of SW480 spheroids. Further studies will examine the significance of the inhibition of the spheroids and the effect of these antagonists on tumor growth.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 601.

Abstract 600: Targeting the hedgehog pathway by LNA (locked nucleic acid) oligonucleotide-based GLI2 RNA antagonists, EZN-4482 and EZN-4496, in vitro and in vivo

Background: Aberrent activation of hedgehog (Hh) signaling has been implicated in the initiation and growth of a number of human malignancies, including those derived from skin, lung, liver, prostate and breast. The GLI family proteins are zinc finger transcription factors and the downstream effectors of Hh pathway, controling expression of the target genes such as GLI1, Ptch1, Cyclin D, and BCL2. Since amplification, overexpression of Hh ligand, and mutations of components along the Hh pathway are found in cancer and cancer stem cells, specific down regulation of GLIs with antisense molecules may offer a novel and effective therapeutic approach for cancer treatment. We report here the biological activities of LNA-based GLI2 mRNA antagonist, EZN-4482 and EZN-4496. Methods: In vitro, the ability of the antagonists to down modulate their direct target, GLI2 mRNA, and to inhibit cell growth was evaluated by qRT-PCR and MTS, respectively, in multiple cell lines of various origins. To identify and investigate the molecular events associated with targeted downmodulation of GLI2, expression of Hh pathway components and downstream effectors were analyzed by gene expression profiling and immnomoblotting analysis. In vivo, GLI2 mRNA down-modulation in PC3 xenograft tumor was evaluated after intravenous administration of the antagonists. The effect of antagonists on tumor growth and survival of mice were evaluated in PC3 prostate tumor grown on the flank and in A549 lung carcinoma cells that had metastasized to the liver respectively. Results: Both antagonists are specific and potent down-modulators of GLI2 mRNA (by transfection, IC50 < 2 nM). Down-modulation of GLI2 mRNA with or without transfection was shown to result in reduction of GLI2 protein in a human breast cancer cell line, HCC-1937, and human prostate cancer cell lines, 15PC3 and C4-2b. In mice bearing PC3 xenograft tumors, systemic administration of EZN-4482 resulted in down-modulation of GLI2, GLI1, and PTCH1 in both PC3 and host stromal cells. Additionally, we show that EZN-4482 prolonged the survival of animals with A549 cell derived liver metastasis derived from A549 cells. Conclusions: EZN-4482 and EZN-4496 are potent and specific GLI2 antagonists in vitro and in vivo. The possible mechanisms of efficacy in vivo may include inhibition of mRNA levels of GLI1/2 and PTCH1 in mouse stromal cells. Therefore, targeted down-modulation of GLI2 using the LNA-based mRNA antagonists may be an effective therapy to treat a broad spectrum of cancers including ones that fail treatment with SMO inhibitor therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 600.

Abstract C141: In vitro and in vivo characterization of two novel β-catenin RNA antagonists, EZN-3889 and 3892

Background: β-Catenin is an important signaling molecule in the Wnt pathway that plays a key role in tumorgenesis. In the absence of Wnt signaling, the cytoplasmic level of β-catenin is kept low due to rapid proteasomal-mediated degradation of GSK3β phosphorylated β-catenin. Activation of Wnt signaling leads to the inactivation of GSK3β, resulting in stabilization and accumulation of β-catenin in the cytoplasm. Consequently, β-catenin translocates into the nucleus, where it binds with members of the T-cell factor (Tcf)/lymphocyte enhancer-binding factor family of transcription factors and activates the expression of many target genes important for cancer development. Most colon cancers have activating mutations in the APC tumor suppressor or in β-catenin itself. Furthermore, activating β-catenin mutations have been found in a variety of other tumors such as melanomas, hepatocellular carcinomas, skin, breast, and prostate cancer, whereas β-catenin is not activated in most normal tissues. Therefore, inhibition of β-catenin is likely to have therapeutic effects in many cancers. We report here the identification of two β-catenin LNA-based mRNA-antagonists, EZN-3889 and EZN-3892.

Material and Methods: In vitro, the ability of the compounds to inhibit mRNA, cell growth, and reporter gene were evaluated by qRT-PCR, MTS, and luciferase assays respectively, in multiple cell lines. In vivo, β-catenin mRNA down-modulation in liver and human tumors, which were grown on the flank of nude mice, was evaluated after intravenous administration of the compounds.

Results: These molecules were potent down-modulators of β-catenin (IC50 = 0.1 to 3 nM) as well as protein (> 80% at 20 nM) of multiple cell lines, when transfected into tumor cells. Growth inhibition appeared to correlate with the status of either APC mutation or activating β-catenin mutations, suggesting that β-catenin is the driver of cancer cells. Interestingly, we found that these two antagonists specifically down modulated β-catenin mRNA and protein effectively in multiple cell lines with a long-lasting effect in the absence of any tranfection reagent. In mice, both molecules significantly down modulated β-catenin mRNA in the liver.

Conclusions: β-catenin antagonists potently and specifically inhibited β-catenin mRNA expression both in vitro and in vivo after intravenous injection. Further studies will examine the antitumor efficacy of the compounds. hese novel agents specifically inhibit a transcription factor that has been difficult to target with conventional agents.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C141.

Abstract C146: LNA (locked nucleic acid) oligonucleotide based GLI2 RNA antagonist EZN-4482 effectively inhibited tumor growth and increased survival of animals with liver metastasis

Background: The Hedgehog (Hh) pathway has been implicated in the growth of a number of human malignancies and cancer stem cells. In the presence of Hh ligands, PTCH1 inhibition of a membrane protein, Smoothened (SMO), is relieved. SMO activation triggers a cascade of downstream events that ultimately activate the zinc finger transcription factors GLI2 and GLI3 and induce transcription of their target genes such as GLI1, PTCH1, Cyclin D, and BCL2. Emerging evidence suggests that GLI1 and GLI2 represent the main activators of Hh pathway due to amplification, overexpression of Hh ligand, and mutations of components along the Hh pathway. Therefore, specific down regulation of GLIs with RNA antagonists such as siRNA and antisense molecules may offer an effective therapeutic approach for cancer treatment. We reveal here the biological activities of LNA-based GLI2 mRNA antagonist, EZN-4482 and 4496.

Material and Methods: In vitro, the ability of the antagonists to down modulate mRNA and cell growth was evaluated by qRT-PCR and MTS respectively. In vivo, GLI2 mRNA down-modulation in tumors, which were grown on the flank of nude mice, was evaluated after intravenous administration of the antagonists. The effect of antagonists on tumor growth and survival of mice were evaluated in PC3 prostate tumor grown on the flank and in A549 lung carcinoma cells that had metastasized to the liver respectively.

Results: Both antagonists, when transfected into tumor cells, were potent down-modulators of GLI2 mRNA (IC50 ≤ 2 nM), resulting caspase ativation and growth inhibition. Interestingly, we found that without any transfection reagent, 1–10 micromolar concentrations of these antagonists were able to down modulate GLI2 mRNA and inhibit the growth of multiple cell lines while their scrambled control oligonucleotides showed no effect, suggesting that the effect was specific. In mice, EZN-4482 (3 mg/kg given q3d x4) down modulated GLI2 mRNA in PC3 prostate tumors. Moreover, using murine specific probes, we found EZN-4482 also inhibited GLI1/2 and PTCH1 in the same tumors. Moderate tumor growth inhibition was found with EZN-4482 in the PC3 xenograft model. Additionally, we show that EZN-4482 prolonged the survival of animals with liver metastasis derived from A549 cells.

Conclusions: GLI2 antagonists potently and specifically inhibited GLI2 mRNA expression and tumor growth in two tumor models. The possible mechanisms of efficacy include inhibition of mRNA levels of GLI1/2 and PTCH1 in mouse stromal cells. While small molecule inhibitors of SMO are being evaluated clinically, this approach is limited to tumors where pathway activation is upstream of GLIs or tumors that are resistant to such inhibitors. Therefore, a GLI2 RNA antagonist may be an effective therapy to treat a broad spectrum of cancers including ones that fail treatment with SMO inhibitor therapy.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C146.

Abstract C144: A locked nucleic acid antisense oligonucleotode against androgen receptor, down-modulates target mRNA and causes antitumor effects in xenograft models of prostate cancer

Background: Androgen-deprivation therapies remain the first line treatment for prostate cancer. Despite an excellent initial response, most of these patients will succumb to the castration resistant form of the disease. Interestingly, even in the presence of castration levels of circulating androgens, these tumors are still dependent on a functional androgen receptor (AR). Therefore, inhibition of AR expression, rather than systemic androgen deprivation, may provide a novel strategy for treatment of advanced prostate cancer. We have developed a novel locked nucleic acid (LNA)-based antisense oligonucleotide (ASO), EZN-4176, that silence AR and is associated with tumor growth inhibition.

Methods: Target mRNA and protein knockdown, growth inhibition, and apoptosis induction effects of EZN-4176 were evaluated by qRT-PCR, western blot analysis, ELISA, MTS assay, and caspase3/7 activity assay, respectively, in AR-positive cancer cell lines (LNCaP, 22RV1) or AR-negative cell line (PC3) in the presence or absence of lipofection (transfection reagent). In vivo, therapeutic efficacy of EZN-4176 was evaluated in AR-positive CWR22 (androgen dependent) and 22Rv1 (castration refractory) tumor models.

Results: EZN-4176 resulted in potent down-modulation of AR mRNA or protein (IC50 <5 nM) when transfected in LNCaP or 22Rv1 cells. Consequently, cell growth was inhibited (IC50 < 10 nM), and caspase 3/7 activity was significantly increased. Additionally, the PSA mRNA and protein levels were significantly decreased after EZN-4176 treatment (IC50 < 5 nM). The biological effects of EZN-4176 were specific as the scrambled LNA-ASO did not down regulate target mRNA, nor were inhibitory effects on growth observed with EZN-4176 in an AR-negative cell line (PC3). In non-transfected cells, EZN-4176 but not the scrambled LNA-ASO down-regulated AR and inhibited the growth of DHT-induced LNCaP cells. In vivo, dose-dependent reduction of AR mRNA (up to 80%) in the liver was observed following intravenous administration of the EZN-4176. Additionally, EZN-4176 treatment dose-dependently inhibited AR (up to 40%), PSA (up to 85%) and TMPRSS2 (up to 50%), mRNA in, 22Rv1 or CWR22 tumor xenografts. In CWR22 tumor xenografts, EZN-4176 treatment also resulted in significant tumor growth inhibition (TGI) (∼55%) (similar to high-dose Casodex® [bicalutamide] treatment). TGI and mRNA knockdown effects in xenografts were specific as scrambled LNA-ASO resulted in no to insignificant response and EZN-4176 had no TGI in PC3 xenograft model. Cy5.5-labeled EZN-4176 was shown to localize in subcutaneous CWR22 or LnCaP tumor xenografts using xenogen imaging system.

Conclusions: Our data suggest that EZN-4176 is a potent LNA-based ASO of AR that causes target down-modulation and TGI effects in vivo and hence may provide a novel strategy to treat advanced prostate cancer.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C144.

Synergistic antitumor activity of ixabepilone (BMS-247550) plus bevacizumab in multiple in vivo tumor models

PURPOSE

Angiogenesis is a critical step in the establishment, growth, and metastasis of solid tumors, and combination of antiangiogenic agents with chemotherapy is an attractive therapeutic option. We investigated the potential of ixabepilone, the first in a new class of antineoplastic agents known as epothilones, to synergize with antiangiogenic agents to inhibit tumor growth.

EXPERIMENTAL DESIGN

In vitro and in vivo cytotoxicity of ixabepilone as single agent and in combination with two targeted antiangiogenic agents, bevacizumab or sunitinib, were examined in preclinical tumor models. Direct effects of the agents against endothelial cells was also examined and compared with the effects of paclitaxel as single agent and in combination with bevacizumab.

RESULTS

Ixabepilone showed robust synergistic antitumor activity in combination with bevacizumab and sunitinib in preclinical in vivo models derived from breast, colon, lung, and kidney cancers. The synergistic antitumor effect was greater with ixabepilone compared with paclitaxel. Furthermore, ixabepilone was more effective than paclitaxel at killing endothelial cells expressing P-glycoprotein in vitro and inhibiting endothelial cell proliferation and tumor angiogenesis in vivo.

CONCLUSIONS

Ixabepilone may enhance the antitumor effects of antiangiogenic therapy by direct cytotoxicity and also indirectly via the killing of tumor-associated endothelial cells. Given that ixabepilone has reduced susceptibility to drug efflux pumps compared with taxanes, these data may explain the increased antiangiogenic and antitumor activity of ixabepilone in combination with antiangiogenic agents. Phase II studies to assess the efficacy and safety of ixabepilone plus bevacizumab in locally recurrent or metastatic breast cancer are planned.

Dasatinib (BMS-354825) pharmacokinetics and pharmacodynamic biomarkers in animal models predict optimal clinical exposure

PURPOSE

Chronic myeloid leukemia (CML) is caused by reciprocal translocation between chromosomes 9 and 22, forming BCR-ABL, a constitutively activated tyrosine kinase. Imatinib mesylate, a selective inhibitor of BCR-ABL, represents current frontline therapy for CML; however, emerging evidence suggests that drug resistance to imatinib may limit its long-term success. To improve treatment options, dasatinib (BMS-354825) was developed as a novel, oral, multi-targeted kinase inhibitor of BCR-ABL and SRC family kinases. To date, dasatinib has shown promising anti-leukemic activity in preclinical models of CML and in phase I/II clinical studies in patients with imatinib-resistant or imatinib-intolerant disease.

EXPERIMENTAL DESIGN

The pharmacokinetic and pharmacodynamic biomarkers of dasatinib were investigated in K562 human CML xenografts grown s.c. in severe combined immunodeficient mice. Tumoral levels of phospho-BCR-ABL/phospho-CrkL were determined by Western blot.

RESULTS

Following a single oral administration of dasatinib at a preclinical efficacious dose of 1.25 or 2.5 mg/kg, tumoral phospho-BCR-ABL/phospho-CrkL were maximally inhibited at approximately 3 hours and recovered to basal levels by 24 hours. The time course and extent of the inhibition correlated with the plasma levels of dasatinib in mice. Pharmacokinetic/biomarker modeling predicted that the plasma concentration of dasatinib required to inhibit 90% of phospho-BCR-ABL in vivo was 10.9 ng/mL in mice and 14.6 ng/mL in humans, which is within the range of concentrations achieved in CML patients who responded to dasatinib treatment in the clinic.

CONCLUSIONS

Phospho-BCR-ABL/phospho-CrkL are likely to be useful clinical biomarkers for the assessment of BCR-ABL kinase inhibition by dasatinib.

Cetuximab preclinical antitumor activity (monotherapy and combination based) is not predicted by relative total or activated epidermal growth factor receptor tumor expression levels

Although Erbitux (cetuximab) has proven therapeutic benefit in the clinical setting, the molecular determinants predicting responsiveness to this agent are still not very well understood. Here, we assessed the relationship between basal total and activated (pY1068) epidermal growth factor receptor (EGFR) levels in a tumor and the responsiveness to cetuximab monotherapy or combination-based treatment using human xenograft models. Cetuximab treatment alone (0.25-1 mg/mouse/injection, q3d, i.p.) effectively delayed the growth of GEO and L2987 tumors by a minimum of 10 days corresponding to log cell kill values of >or=1.0. Borderline activity was seen in the A549 and WiDr xenografts. However, cetuximab failed to show any significant antitumor activity in the HT29, HCT116, LOVO, Colo205, LX-1, HCC70, and N87 models. All of the studied tumors had detectable yet variable levels of EGFR. For combination regimens, cetuximab (1 mg/mouse/injection, q3dx5, i.p.) and cisplatin (4.5 mg/kg/injection, q3dx5, i.v.) proved to be significantly more efficacious than individual monotherapies in the cisplatin-refractory yet cetuximab-responsive GEO tumor model (P < 0.001). However, no therapeutic enhancement was observed in the cisplatin and cetuximab weakly responsive A549 xenograft. Similarly, combinations of CPT-11 (48 mg/kg/injection, q3dx5, i.v.) with cetuximab (1 mg/mouse/injection, q3dx5, i.p.) failed to show any improvements over individual monotherapies in the cetuximab resistant/weakly responsive HT29, A549, and WiDr models. We conclude that preclinical activity associated with cetuximab monotherapy does not correlate directly with relative basal levels of total or activated (pY1068) EGFR in a tumor. Moreover, robust single-agent activity by cetuximab may be the best predictor for this agent to potentiate chemotherapy-mediated antitumor activities.

Prediction of active drug plasma concentrations achieved in cancer patients by pharmacodynamic biomarkers identified from the geo human colon carcinoma xenograft model

PURPOSE

Epidermal growth factor receptor (EGFR), a protein tyrosine kinase expressed in many types of human cancers, has been strongly associated with tumor progression. Cetuximab is an IgG(1) anti-EGFR chimeric mouse/human monoclonal antibody that has been approved for the treatment of advanced colon cancer. Using human tumor xenografts grown in nude mice, we have determined the in vivo pharmacodynamic response of cetuximab at efficacious doses. Three pharmacodynamic end points were evaluated: tumoral phospho-EGFR, tumoral mitogen-activated protein kinase (MAPK) phosphorylation, and Ki67 expression.

EXPERIMENTAL DESIGN

The pharmacodynamic study was conducted in nude mice bearing Geo tumors following a single i.p. administration of 0.25 and 0.04 mg. The tumors were analyzed by immunohistochemistry. The levels of phospho-EGFR were quantitated by an ELISA assay.

RESULTS

At 0.25 mg, phospho-EGFR was maximally inhibited by 91% at 24 hours, whereas the level of inhibition decreased to 72% by 72 hours. At 0.04 mg, the maximum inhibition of phospho-EGFR was 53% at 24 hours, whereas the level of inhibition decreased to 37% by 72 hours. The time course of phospho-EGFR inhibition and recovery seemed to correlate with the pharmacokinetics of cetuximab. Immunohistochemical analysis showed that phospho-MAPK and Ki67 expression were inhibited between 24 and 72 hours at 0.25 and 0.04 mg. A pharmacokinetic/pharmacodynamic model was established and predicted that the plasma concentration of cetuximab required to inhibit 90% of phospho-EGFR was 67.5 mug/mL.

CONCLUSIONS

Phospho-EGFR/phospho-MAPK could be useful clinical biomarkers to assess EGFR inhibition by cetuximab.

Correlation of pharmacokinetics with the antitumor activity of Cetuximab in nude mice bearing the GEO human colon carcinoma xenograft

PURPOSE

The epidermal growth factor receptor (EGFR), a protein tyrosine kinase expressed in many types of human cancers including colon and breast, has been strongly associated with tumor progression. Cetuximab, an IgG1 anti-EGFR chimeric mouse/human monoclonal antibody, has been proven to be effective in the treatment of advanced colon cancer. To date, there has not been a study to systematically evaluate the pharmacokinetics (PK) of Cetuximab in a preclinical model and to further explore any correlation of drug exposure between animal models and cancer patients. In the present study, we characterized the PK of Cetuximab in nude mice at efficacious dose levels and further compared the preclinical optimal dose and active plasma drug concentration with those determined in clinical studies.

EXPERIMENTAL DESIGN

The antitumor activity of Cetuximab was evaluated using the GEO human colon carcinoma xenografts implanted subcutaneously in nude mice. The drug was administered ip every 3 days for five total injections (inj) (q3dx5) at dose levels ranging from 1 mg/inj to 0.04 mg/inj. The plasma PK of Cetuximab was determined at dose levels of 1.0, 0.25, and 0.04 mg/inj with a single bolus iv or ip administration in nude mice. The tumoral PK of Cetuximab was determined at dose levels of 0.25, and 0.04 mg/inj with a single bolus ip administration in nude mice bearing GEO tumor xenografts. The plasma and tumoral levels of Cetuximab were quantitated by an ELISA assay.

RESULTS

Cetuximab demonstrated a dose-dependent antitumor activity at dose levels of 0.25, 0.1, and 0.04 mg/inj, with a statistically significant tumor growth delay (in reaching a tumor target size of 1 gm) of 18 days (P < 0.001), 12.3 days (P < 0.01), and 10 days (P < 0.01) for 0.25, 0.1, and 0.04 mg/inj, respectively. A separate study employing the same treatment schedule showed that Cetuximab was equally active at dose levels ranging from 0.25 mg/inj to 1 mg/inj. Therefore, dose levels of Cetuximab from 1 mg/inj to 0.04 mg/inj can be considered to be within the efficacious range, while dose levels of 0.25 mg/inj or higher appeared to be optimal for the antitumor activity of Cetuximab in the GEO tumor model. When Cetuximab was given iv to mice, the elimination half life (t(1/2)) was 39.6, 37.8, and 42.2 h for doses of 1.0, 0.25, and 0.04 mg/inj, respectively, suggesting a similar disposition kinetics of Cetuximab within this dose range. The volume of distribution (V(d)) ranged from 0.062 l/kg to 0.070 l/kg, suggesting that Cetuximab is primarily confined to the plasma compartment with limited peripheral tissue distribution. Clearance (CL) was similar and no apparent PK saturation was observed across the dose ranging from 0.04 mg/inj to 1.0 mg/inj. When mice were administered with a single bolus ip administration at doses of 1, 0.25, and 0.04 mg/inj, the maximum plasma concentration (C(max)) was 407.6, 66.4, and 16.5 microg/ml. The area under the curve of plasma drug concentration (AUC) was 19212.4, 3182.4, and 534.5 microg/ml h, for 1.0, 0.25, and 0.04 mg/inj, respectively. The average steady state plasma concentration (C(ss avg)) for the multiple dosing schedule was estimated to be 73.1 microg/ml at 0.25 mg/inj and was considered as an active plasma drug concentration. The maximum tumoral concentration of Cetuximab was 2.6 and 0.53 ng/mg-tumor while the tumoral drug exposure was 112.6 and 18.3 ng/mg h for 0.25 and 0.04 mg/inj, respectively. The EGFR was estimated to be nearly completely occupied by Cetuximab at the optimal dose of 0.25 mg/inj.

CONCLUSION

In the present study, we compared the preclinical optimal dose and the corresponding active plasma concentration determined in mice with those being observed in cancer patients, i.e. 65-100 microg/ml. The preclinical optimal dose of 0.25 mg/inj was significantly lower than the current clinical dose. However, the active plasma concentration at 0.25 mg/inj is within the range of the active drug concentrations in cancer patients treated with Cetuximab under the current optimal dosing regimen. It appears that the active plasma drug concentration determined in preclinical model predicts better than the optimal preclinical dose for the clinical development of antibody drugs.

Discovery of N-(2-chloro-6-methyl- phenyl)-2-(6-(4-(2-hydroxyethyl)- piperazin-1-yl)-2-methylpyrimidin-4- ylamino)thiazole-5-carboxamide (BMS-354825), a dual Src/Abl kinase inhibitor with potent antitumor activity in preclinical assays

A series of substituted 2-(aminopyridyl)- and 2-(aminopyrimidinyl)thiazole-5-carboxamides was identified as potent Src/Abl kinase inhibitors with excellent antiproliferative activity against hematological and solid tumor cell lines. Compound 13 was orally active in a K562 xenograft model of chronic myelogenous leukemia (CML), demonstrating complete tumor regressions and low toxicity at multiple dose levels. On the basis of its robust in vivo activity and favorable pharmacokinetic profile, 13 was selected for additional characterization for oncology indications.

Discovery of N-(2-chloro-6-methyl- phenyl)-2-(6-(4-(2-hydroxyethyl)- piperazin-1-yl)-2-methylpyrimidin-4- ylamino)thiazole-5-carboxamide (BMS-354825), a dual Src/Abl kinase inhibitor with potent antitumor activity in preclinical assays

A series of substituted 2-(aminopyridyl)- and 2-(aminopyrimidinyl)thiazole-5-carboxamides was identified as potent Src/Abl kinase inhibitors with excellent antiproliferative activity against hematological and solid tumor cell lines. Compound 13 was orally active in a K562 xenograft model of chronic myelogenous leukemia (CML), demonstrating complete tumor regressions and low toxicity at multiple dose levels. On the basis of its robust in vivo activity and favorable pharmacokinetic profile, 13 was selected for additional characterization for oncology indications.

Peripartum hysterectomy

OBJECTIVES

To review the cases receiving peripartum hysterectomies treated in this hospital during the period 1967-1995. Clinical characteristics, indications, and results were more closely analyzed.

STUDY DESIGN

A chart review of all cases operated since January 1967 to December 1995 was done. Demographic and clinical data were extracted, coded, and entered into a computer file for analysis. Indications, type of operation, pre-op planning or emergency decision, blood loss, transfusion, complications, were compared and cross-tabulated. Statistical analysis included: chi-square and Fisher exact tests, where appropriate, and two-sample t test.

RESULTS

In 58% of 217 cases the operation was planned, and total hysterectomy was done in 94%. Indications changed through the years, from predominantly elective to almost exclusively emergencies. These were mostly bleeding complications, in particular placenta previa and/or accreta. The presence of a uterine scar or submucous fibroid was associated with 79% (26/33) of accretas, and 51% (19/37) of previas. Among the 126 planned, 57% did not receive a transfusion and 84% of 91 emergencies did have one. The average amount of blood received by the latter was 3009 ml compared to 1262 ml for the former (p < 0.0001). There was a direct relationship between amount of blood loss and volume transfused. There were 26% intraoperatory bleeding complications and 5% urinary tract injuries. Postoperatory morbidity such as bleeding, infections, wound dehiscence, and others was observed in 17% of planned, and 23% of emergencies. Twelve patients needed another operation to treat some of these complications. There were no deaths recorded.

CONCLUSIONS

Peripartum hysterectomy is a major operation, and in current times almost always an emergency with high risk for significant blood loss. The obstetrician should be ready to do it, and an early decision should save blood and prevent complications. Postoperative complications, mostly bleeding and infections may be severe. Early intervention and proper technique facilitate good outcomes.