Abstract PD3-04: PAK-1 amplified breast cancer cell lines are preferentially sensitive to PAK inhibition with G-5555

The small GTP-binding proteins Rac1 and Cdc42 stimulate activity of the serine/threonine kinase p21-activated kinase-1 (PAK-1) to drive growth factor signaling networks and Ras-driven tumorigenesis. Genomic amplification and over-expression of PAK1 are prevalent in luminal breast cancer and correlate with poor clinical outcome. Here we use a novel and selective small molecule inhibitor, G-5555, of the group I PAKs (PAK1, 2, and 3) to evaluate the importance of PAK1 in promoting growth of PAK1 amplified breast cancer cells. Cell lines with amplification of PAK1 were found to be more sensitive to PAK1 inhibition than non-amplified cell lines. Additionally, reverse phase protein array (RPPA) was used to assess the effects of PAK1 inhibition on a wide range of signaling pathways in both amplified and non-amplified cell lines. Reduced levels of phosphorylation of MEK S298 was observed in all cell lines exposed to G-5555 irrespective of amplification status, consistent with PAK1 inhibition in these cell lines. However, modulation of this downstream PAK1 substrate did not correlate with inhibition of cell proliferation or induction of cell death. Cell lines that showed inhibition of proliferation in response to G-5555 also showed enhanced levels of cell death along with apoptosis. Moreover, G-5555 reduced tumor growth in the PAK1 amplified MDA-MB-175 xenograft tumor model. Finally, we compared the in vitro activity of G-5555 with palbociclib, a recently approved inhibitor of the cyclin-dependent kinases CDK4 and CDK6, in PAK1 amplified luminal breast cancer cell lines. Our data supports PAK1 as an attractive target in PAK1 amplified cells and tumors and suggests that inhibiting PAK1 rather than CDK4/6 in this context may be a more attractive therapeutic strategy.

Citation Format: Ong CC, Blackwood E, Jakubiak D, Daemen A, Ramaswamy S, Heise C, Schmidt M, Sanders L, Wilson TR, Huw L, Ndubaku C, Rudolph J, Hoeflich KP, Friedman L, O'Brien T. PAK-1 amplified breast cancer cell lines are preferentially sensitive to PAK inhibition with G-5555. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD3-04.

SPARC Expression Did Not Predict Efficacy of nab-Paclitaxel plus Gemcitabine or Gemcitabine Alone for Metastatic Pancreatic Cancer in an Exploratory Analysis of the Phase III MPACT Trial

PURPOSE

nab-Paclitaxel plus gemcitabine was superior to gemcitabine alone for patients with metastatic pancreatic cancer (MPC) in the phase III MPACT trial. This study evaluated the association of secreted protein acidic and rich in cysteine (SPARC) levels with efficacy as an exploratory endpoint.

EXPERIMENTAL DESIGN

Patients with previously untreated MPC (N = 861) received nab-paclitaxel plus gemcitabine or gemcitabine alone. Baseline SPARC level was measured in the tumor stroma and epithelia (archival biopsies) and plasma. Experiments were performed in pancreatic cancer mouse models in which SPARC was intact or deleted.

RESULTS

SPARC was measured in the tumor stroma of 256 patients (30%), the tumor epithelia of 301 patients (35%), and plasma of 343 patients (40%). Stroma-evaluable samples were from metastases (71%), from the pancreas (11%), or of unidentifiable origin (insufficient tissue to determine; 17%). For all patients, stromal SPARC level [high (n = 71) vs. low (n = 185)] was not associated with overall survival (OS; HR, 1.019; P = 0.903); multivariate analysis confirmed this lack of association. There was no association between stromal SPARC level and OS in either treatment arm. Neither tumor epithelial SPARC nor plasma SPARC was associated with OS. Results from a SPARC knockout mouse model treated with nab-paclitaxel plus gemcitabine revealed no correlation between SPARC expression and tumor progression or treatment efficacy.

CONCLUSIONS

SPARC levels were not associated with efficacy in patients with MPC. This exploratory analysis does not support making treatment decisions regarding nab-paclitaxel plus gemcitabine or gemcitabine alone in MPC based on SPARC expression.

Abstract LB-94: Highlights of innovative preclinical studies which guided the rapid bench to bedside development of nab-paclitaxel plus gemcitabine combination for the treatment of pancreatic cancer

Background and Aim: Advanced pancreatic cancer is both deadly and difficult to treat with success. Here, we disseminate the results of comprehensive preclinical studies which laid a strong foundation for the rapid bench to bedside development of nab-paclitaxel, an albumin-bound formulation of paclitaxel, in combination with gemcitabine, a regimen recently approved by U.S. Food and Drug Administration as a first-line treatment for patients with metastatic pancreatic cancer.

Materials and Methods: We enrolled a total of 650 mice with established pancreatic tumors originated from a collection of patient-derived pancreatic cancer xenografts. The present study investigated the anti-tumor activity, survival advantage and mechanism of action of nab-paclitaxel or Cremophor EL™ (CreEL)-based paclitaxel monotherapy and in combination with gemcitabine.

Results: When tested in mice with subcutaneous tumors originating from 11 separate individual patient xenografts, nab-paclitaxel plus gemcitabine treatment demonstrated superior tumor regression response, robustly depleted the tumor desmoplatic stroma, leading to enhanced gemcitabine uptake (2.8-fold) in the tumor compared to tumors in the gemcitabine alone treated mice. In orthotopic models, nab-paclitaxel treatment leads to an average of 3.64-fold decrease in primary tumor volumes compared to CreEL-based paclitaxel. Intra-tumor stromal collapse combined with decreased tumor cell proliferation was clearly evident in the primary tumors of nab-paclitaxel treated mice compared to CreEL-based paclitaxel, when the mice were sacrificed immediately after five consecutive day's treatment or three weeks after the final dose of the agents. In a highly aggressive orthotopic model, nab-paclitaxel plus gemcitabine treatment prevented primary tumor progression, and metastatic spread to liver, lymph nodes and diaphragm. While CreEL-based paclitaxel plus gemcitabine treatment failed to enhance mouse survival compared to gemcitabine monotherapy, the nab-paclitaxel plus gemcitabine combination proved statistically significant (p=0.0133) in enhancing survival. nab-paclitaxel monotherapy demonstrated statistically significant survival advantage compared to CreEL-based paclitaxel monotherapy (p=0.0072). Remarkably, nab-paclitaxel monotherapy was equivalent to nab-paclitaxel plus gemcitabine in providing survival advantage in a highly aggressive metastatic model of pancreatic cancer.

Conclusion: Our results demonstrated that co-treatment with nab-paclitaxel and gemcitabine resulted in superior tumor regression response, stromal depletion and enhanced intra-tumoral gemcitabine uptake compared with either single agent alone. nab-paclitaxel demonstrated superior anti-tumor activity and provided a statistically significant survival advantage compared to CreEL-based paclitaxel. Our results provide further rationale for future preclinical and clinical trials in pancreatic cancer using nab-paclitaxel as a backbone therapy in combination with novel experimental and targeted agents.

Acknowledgements: The study was supported by funding from Celgene Corporation and AACR-Stand Up To Cancer Dream Team Translational Cancer Research Grant (SU2C-AACR-DT0509).

Citation Format: N.V Rajeshkumar, Shinichi Yabuuchi, Shweta G. Pai, Scott Bateman, Ellen Filvaroff, Daniel W. Pierce, Carla Heise, Daniel D. Von Hoff, Anirban Maitra, Manuel Hidalgo. Highlights of innovative preclinical studies which guided the rapid bench to bedside development of nab-paclitaxel plus gemcitabine combination for the treatment of pancreatic cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-94. doi:10.1158/1538-7445.AM2014-LB-94

An activin receptor IIA ligand trap promotes erythropoiesis resulting in a rapid induction of red blood cells and haemoglobin

Sotatercept (ACE-011), a recombinant human fusion protein containing the extracellular domain of the human Activin receptor IIA, binds to and inhibits activin and other members of the transforming growth factor -β (TGF-β) superfamily. Administration of sotatercept led to a rapid and sustained increase in red blood cell (RBC) count and haemoglobin (Hb) in healthy volunteers (phase I clinical trials), but the mechanism is not fully understood. Mice treated with RAP-011 (murine ortholog of ACE-011) respond with a rapid (within 24 h) increase in haematocrit, Hb, and RBC count. These effects are accompanied by an equally rapid stimulation of late-stage erythroid precursors in the bone marrow (BM). RAP-011 also induces a significant increase in erythroid burst-forming units and erythropoietin, which could contribute to additional, sustained effects on RBC production. Further in vitro co-culture studies demonstrate that BM accessory cells are required for RAP-011 effects. To better understand which TGF-β family ligand(s) mediate RAP-011 effects, we evaluated the impact of several of these ligands on erythroid differentiation. Our data suggest that RAP-011 may act to rescue growth differentiation factor 11/Activin A-induced inhibition of late-stage erythropoiesis. These data define the mechanism of action of a novel agent that regulates RBC differentiation and provide the rationale to develop sotatercept for the treatment of anaemia and ineffective erythropoiesis.

Abstract 5666: Albumin and paclitaxel co-localize in endocytic vesicles in HUVEC cells, and uptake is blocked by Cremophor EL

Nab®-paclitaxel is an albumin-bound nanoparticle formulation of paclitaxel (ptx) that does not contain Cremophor EL (CrEL), and results in higher drug levels in xenografts and increased clinical activity in breast and lung cancers compared to ptx formulated with CrEL (Taxol®). Above the critical micellar concentration of 0.009%, CrEL forms long-lived micelles in circulation that can sequester ptx (peak plasma concentration in clinical use is 0.3%). Previous studies have shown CrEL reduces ptx binding to albumin, and Taxol® has reduced association with, and transport across endothelial cells compared to nab®-ptx (Desai, CCR 2006).

Endothelial cells take up albumin, which is trafficked into recycling or transcytosis pathways or into lysosomes for degradation. Here, we explore mechanisms of uptake and trafficking of albumin and ptx in endothelial cells and the effect of CrEL on these events. Using fluorescence microscopy, we visualized the uptake of rhodamine-albumin and fluorescent ptx (Flutax). Albumin was present in EEA1-positive early endosomes and LAMP1-positive lysosomes. Notably, ptx was also present in vesicular structures and was often co-localized with albumin. The uptake of albumin was blocked by increasing concentrations (0.003%-0.3%) of CrEL, and also by inhibitors of caveolin-mediated endocytosis including indomethacin (blocks internalization of caveolae) and methyl-β-cyclodextrin (prevents formation of lipid rafts).

The effect of CrEL on paclitaxel and albumin cellular uptake was confirmed by flow cytometry studies. 0.3% CrEL reduced the uptake of Flutax in DMSO, Flutax-modified nab®-ptx, and FITC-labeled albumin to close to background levels in both HUVEC and PC3 cells. Thus, in addition to its drug sequestration activity, CrEL directly affects endocytosis.

We further evaluated CrEL effects on Flutax and ptx transport across endothelial monolayers in transwell chambers using a fluorescence detection assay. Two-fold more ptx crossed monolayers exposed to Flutax-containing nab®-ptx as compared to Taxol®. The effects of 0.001% to 0.3% CrEL on ptx transport at varying timepoints were investigated by mass spectrometry. Dose-dependent inhibition was observed, with a 3-fold reduction in transported ptx at 24 hrs.

In summary, we have demonstrated that ptx co-localizes with albumin in endothelial cells, suggesting that the nab-ptx complex can remain intact within cells. Furthermore, CrEL interferes with albumin uptake at clinically relevant concentrations, thereby affecting paclitaxel cellular uptake and transport. These mechanistic studies further elucidate the basis of increased delivery of drug into the target cells by the nab®-ptx formulation as compared to Taxol®.

Citation Format: Xiping Liu, Carrie Brachmann, Sean Hong, Shijuan Wu, Zeen Tong, Tapas De, Willard Foss, Gondi Kumar, Sekhar Surapaneni, Rajesh Chopra, Daniel Pierce, Carla Heise. Albumin and paclitaxel co-localize in endocytic vesicles in HUVEC cells, and uptake is blocked by Cremophor EL. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5666. doi:10.1158/1538-7445.AM2013-5666

The class I HDAC inhibitor Romidepsin targets inflammatory breast cancer tumor emboli and synergizes with paclitaxel to inhibit metastasis

Inflammatory breast cancer (IBC) is the most metastatic variant of locally advanced breast cancer. IBC has distinctive characteristics including invasion of tumor emboli into the skin and rapid disease progression. Given our previous studies suggesting that HDAC inhibitors have promise in targeting IBC, the present study revealed that the class I HDAC inhibitor Romidepsin (FK-288, Istodax; Celgene Corporation, Summit, NJ) potently induced destruction of IBC tumor emboli and lymphatic vascular architecture. associated with inhibition of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1alpha, (HIF1alpha) proteins in the Mary-X pre-clinical model of IBC. Romidepsin treatment induced clinically relevant biomarkers in including induction of acetylated Histone 3 (Ac-H3) proteins, apoptosis, and increased p21WAF1/CIP1. Romidepsin, alone and synergistically when combined with Paclitaxel, effectively eliminated both primary tumors and metastatic lesions at multiple sites formed by the SUM149 IBC cell line. This is the first report of the ability of an HDAC inhibitor to eradicate IBC tumor emboli, to destroy the integrity of lymphatic vessel architecture and to target metastasis. Furthermore, Romidepsin, in combination with a taxane, warrants evaluation as a therapeutic strategy that may effectively target the skin involvement and rapid metastasis that are hallmarks of IBC.

Lenalidomide efficacy in activated B-cell-like subtype diffuse large B-cell lymphoma is dependent upon IRF4 and cereblon expression

Durable responses with lenalidomide monotherapy have been reported in patients with non-Hodgkin lymphoma. In relapsed/refractory diffuse large B-cell lymphoma (DLBCL), higher responses were observed in the activated B-cell-like (ABC) subtype than in the germinal centre B-cell-like subtype. Herein, the molecular mechanisms involved in the differential efficacy of lenalidomide in DLBCL subtypes were investigated. Using DLBCL cell lines, lenalidomide treatment was found to preferentially suppress proliferation of ABC-DLBCL cells in vitro and delay tumour growth in a human tumour xenograft model, with minimal effect on non-ABC-DLBCL cells. This tumouricidal effect was associated with downregulation of interferon regulatory factor 4 (IRF4), a hallmark of ABC-DLBCL cells. IRF4 inhibition by lenalidomide induced downregulation of B-cell receptor (BCR)-dependent NF-κB. Whereas IRF4-specific small, interfering RNA mimicked the effects of lenalidomide reducing NF-κB activation, IRF4 overexpression enhanced NF-κB activation and conferred resistance to lenalidomide. These findings indicate the crucial role of IRF4 inhibition in lenalidomide efficacy in ABC cells. Furthermore, lenalidomide-induced IRF4 downregulation required the expression of cereblon, a molecular target of lenalidomide. Taken together, these findings suggest that lenalidomide has direct antitumour activity against DLBCL cells, preferentially ABC-DLBCL cells, by blocking IRF4 expression and the BCR-NF-κB signalling pathway in a cereblon-dependent manner.

Histone deacetylase inhibitor MGCD0103 synergizes with gemcitabine in human pancreatic cells

Histone deacetylase inhibitors are a group of recently developed compounds that modulate cell growth and survival. We evaluated the effects of the histone deacetylase inhibitor MGCD0103 on growth of pancreatic carcinoma models following single agent treatment and in combination with gemcitabine. MGCD0103 inhibited tumor cell growth and acted synergistically with gemcitabine to enhance its cytotoxic effects. Gene expression analysis identified the cell cycle pathway as one of the most highly modulated gene groups. Our data suggest that MGCD0103 + gemcitabine might be an effective treatment for gemcitabine-refractory pancreatic cancer.

The class-I HDAC inhibitor MGCD0103 induces apoptosis in Hodgkin lymphoma cell lines and synergizes with proteasome inhibitors by an HDAC6-independent mechanism

Inhibition of histone deacetylase 6 (HDAC6)-dependent aggresome function by pan HDAC inhibitors was recently reported to be a key mechanism underlying the synergistic activity between proteasome inhibitors and HDAC inhibitors in a variety of tumour types. Because these combinations induce significant thrombocytopenia in vivo, we examined whether less toxic, isotype-selective HDAC inhibitors may still synergize with proteasome inhibitors, and if so, by what mechanisms. Here, we showed that the class I HDAC inhibitor, MGCD0103, has a potent antiproliferative activity in Hodgkin lymphoma (HL) cell lines. Furthermore, MGCD0103 induced tumour necrosis factor α (TNF-α) expression and secretion, which was associated with nuclear factor (NF)-κB activation. Selective inhibition of TNF-α expression by short interfering mRNA, or inhibition of MGCD0103-induced NF-kB activation by proteasome inhibitors enhanced MGCD0103-induced cell death. Thus, our results demonstrate that MGCD0103 may synergize with proteasome inhibitors by HDAC6-independent mechanisms, providing mechanistic rationale for exploring this potentially less toxic combination for the treatment of lymphoma.

Azacitidine and decitabine have different mechanisms of action in non-small cell lung cancer cell lines

Azacitidine (AZA) and decitabine (DAC) are cytidine azanucleoside analogs with clinical activity in myelodysplastic syndromes (MDS) and potential activity in solid tumors. To better understand the mechanism of action of these drugs, we examined the effects of AZA and DAC in a panel of non-small cell lung cancer (NSCLC) cell lines. Of 5 NSCLC lines tested in a cell viability assay, all were sensitive to AZA (EC₅₀ of 1.8-10.5 µM), while only H1299 cells were equally sensitive to DAC (EC₅₀ of 5.1 µM). In the relatively DAC-insensitive cell line A549, both AZA and DAC caused DNA methyltransferase I depletion and DNA hypomethylation; however, only AZA significantly induced markers of DNA damage and apoptosis, suggesting that mechanisms in addition to, or other than, DNA hypomethylation are important for AZA-induced cell death. Cell cycle analysis indicated that AZA induced an accumulation of cells in sub-G1 phase, whereas DAC mainly caused an increase of cells in G2/M. Gene expression analysis of AZA- and DAC-treated cells revealed strikingly different profiles, with many genes distinctly regulated by each drug. In summary, while both AZA and DAC caused DNA hypomethylation, distinct effects were demonstrated on regulation of gene expression, cell cycle, DNA damage, and apoptosis.

Abstract LB-59: Amrubicin, a third-generation synthetic anthracycline, is active in anthracycline-resistant tumors

Amrubicin, a third generation synthetic anthracycline and a potent topoisomerase (topo) II inhibitor, is approved in Japan for the treatment of lung cancer (both small-cell and non-small cell) and is being evaluated in a phase III trial in the North America and Europe for the second line treatment of SCLC. The aim of these studies was to evaluate the cross-resistance of amrubicin with other anthracyclines (doxorubicin, epirubicin) and the topo-II inhibitor etoposide, and to identify potential mechanisms of resistance to amrubicin. The doxorubicin-resistant cell lines H69-AR, MES-SA-DX5 & NCI-ADR/RES were confirmed to be resistant to doxorubicin (∼25-fold relative resistance), however, their resistance to amrubicin was low or absent (∼2-fold relative resistance). Additionally, a number of primary human ovarian and breast tumor explants that were resistant to doxorubicin and/or etoposide retained sensitivity to amrubicin. Unlike doxorubicin, amrubicin induced DNA damage, G2M cell cycle arrest and apoptosis in both doxorubicin-sensitive and -resistant lines at or below clinically relevant plasma concentrations (∼10 uM). Furthermore, in contrast to doxorubicin, fluorescence time-lapse imaging demonstrated relatively small differences in amrubicin uptake and accumulation kinetics in doxorubicin-sensitive and resistant cell lines. Using gene expression profiling studies, we showed that a greater number of genes were regulated by amrubicin than by doxorubicin in both OVCAR8 and NCI-ADR/RES lines. Amrubicin is a moderate P-glycoprotein (Pgp) substrate; however, we demonstrated that the inhibitory effect and accumulation of amrubicin is not solely modulated by Pgp in cell lines over-expressing efflux pumps including Pgp. We postulate that the high intracellular accumulation and retention of amrubicin is a result of rapid influx due to the high intrinsic permeability and lipophilic properties of amrubicin. This may explain why amrubicin overcomes pleiotropic drug resistance. In summary, we demonstrated that amrubicin has a distinct mode of action compared with other anthracyclines, is less susceptible to typical anthracycline resistance mechanisms and therefore, may be useful in the treatment of anthracycline-resistant tumors.

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 LB-59.

A comparison of azacitidine and decitabine activities in acute myeloid leukemia cell lines

BACKGROUND

The cytidine nucleoside analogs azacitidine (AZA) and decitabine (DAC) are used for the treatment of patients with myelodysplastic syndromes and acute myeloid leukemia (AML). Few non-clinical studies have directly compared the mechanisms of action of these agents in a head-to-head fashion, and the agents are often viewed as mechanistically similar DNA hypomethylating agents. To better understand the similarities and differences in mechanisms of these drugs, we compared their in vitro effects on several end points in human AML cell lines.

METHODOLOGY/PRINCIPAL FINDINGS

Both drugs effected DNA methyltransferase 1 depletion, DNA hypomethylation, and DNA damage induction, with DAC showing equivalent activity at concentrations 2- to 10-fold lower than AZA. At concentrations above 1 microM, AZA had a greater effect than DAC on reducing cell viability. Both drugs increased the sub-G1 fraction and apoptosis markers, with AZA decreasing all cell cycle phases and DAC causing an increase in G2-M. Total protein synthesis was reduced only by AZA, and drug-modulated gene expression profiles were largely non-overlapping.

CONCLUSIONS/SIGNIFICANCE

These data demonstrate shared mechanisms of action of AZA and DAC on DNA-mediated markers of activity, but distinctly different effects in their actions on cell viability, protein synthesis, cell cycle, and gene expression. The differential effects of AZA may be mediated by RNA incorporation, as the distribution of AZA in nucleic acid of KG-1a cells was 65:35, RNA:DNA.

A phase I pharmacokinetic and pharmacodynamic study of TKI258, an oral, multitargeted receptor tyrosine kinase inhibitor in patients with advanced solid tumors

PURPOSE

To determine the maximum tolerated dose (MTD) dose-limiting toxicity, and pharmacokinetic and pharmacodynamic profile of TKI258 (formerly CHIR-258).

EXPERIMENTAL DESIGN

A phase I dose escalating trial in patients with advanced solid tumors was performed. Treatment was initially as single daily doses on an intermittent 7-day on/7-day off schedule. Following a protocol amendment, a second schedule comprised, during cycle 1, 7-day on/7-day off treatment followed by 14 days of continuous daily dosing; subsequent cycles comprised 28 days of daily dosing. Pharmacokinetics and evaluation of phosphorylated extracellular signal-regulated kinase (ERK) in peripheral blood mononuclear cells were done during the first 28 days of each schedule.

RESULTS

Thirty-five patients were treated in four intermittent (25-100 mg/d) and three continuous (100-175 mg/d) dosing cohorts. Observed drug-related toxicities were nausea and vomiting, fatigue, headache, anorexia, and diarrhea. Dose-limiting toxicities were grade 3 hypertension in one patient at 100 mg continuous dosing, grade 3 anorexia in a second patient at 175 mg, and grade 3 alkaline phosphatase elevation in a third patient at 175 mg. One patient had a partial response (melanoma) and two patients had stable disease >6 months. TKI258 pharmacokinetics were linear over the dose range of 25 to 175 mg. Five of 14 evaluable patients had modulation of phosphorylated ERK levels.

CONCLUSIONS

The MTD was defined as 125 mg/d. Evidence of antitumor activity in melanoma and gastrointestinal stromal tumors warrants further investigation, and other phase I studies are ongoing. Further pharmacodynamic evaluation is required in these studies to evaluate the biological effects of TKI258.

Recombinant interleukin-2 significantly augments activity of rituximab in human tumor xenograft models of B-cell non-Hodgkin lymphoma

Recombinant interleukin-2 (rIL-2) is a pleiotropic cytokine that activates select immune effector cell responses associated with antitumor activity, including antibody-dependent cellular cytotoxicity (ADCC). Rituximab is an anti-CD20 monoclonal antibody that activates ADCC in non-Hodgkin lymphoma (NHL). The ability of rIL-2 to augment rituximab-dependent tumor responses was investigated. The efficacy of rIL-2 in combination with rituximab was evaluated in 2 NHL tumor xenograft models: the CD20hi, rituximab-sensitive, low-grade Daudi model and the CD20lo, aggressive, rituximab-resistant Namalwa model. Combination of rIL-2 plus rituximab was synergistic in a rituximab-sensitive Daudi tumor model, as evidenced by significant tumor regressions and increased time to tumor progression, compared with rIL-2 and rituximab single agents. In contrast, rituximab-resistant Namalwa tumors were responsive to single-agent rIL-2 and showed an increased response when combined with rituximab. Using in vitro killing assays, rIL-2 was shown to enhance activity of rituximab by activating ADCC and lymphokine-activated killer activity. Additionally, the activity of rIL-2 plus rituximab F(ab')2 was similar to that of rIL-2 alone, indicating a critical role for immunoglobulin G1 Fc-FcgammaR-effector responses in mediating ADCC. Antiproliferative and apoptotic tumor responses, along with an influx of immune effector cells, were observed by immunohistochemistry. Collectively, the data suggest that rIL-2 mediates potent tumoricidal activity against NHL tumors, in part, through activation and trafficking of monocytes and natural killer cells to tumors. These data support the mechanistic and therapeutic rationale for combination of rIL-2 with rituximab in NHL clinical trials and for single-agent rIL-2 in rituximab-resistant NHL patients.

MIP-1alpha (CCL3) is a downstream target of FGFR3 and RAS-MAPK signaling in multiple myeloma

Overexpression of fibroblast growth factor receptor 3 (FGFR3) is a hallmark of t(4;14) multiple myeloma (MM). To dissect the mechanism of FGFR3 oncogenesis in MM, we used 3 FGFR selective kinase inhibitors-CHIR258, PD173074, and SU5402-and FGFR3-specific siRNA to modulate FGFR3 activity. Conversely, the ligand FGF was used to stimulate FGFR3 function in human MM cells. The transcriptional response to FGFR3 modification was recorded, and gene expression changes common to all 5 modifiers were documented. Ten genes were commonly regulated. Macrophage inflammatory protein-1 alpha (MIP-1alpha) was the single most differentially altered gene. MIP-1 alpha promoter function, gene expression, and protein secretion were each down-regulated following inhibition of FGFR3 signaling. Down-regulation of MIP-1 alpha was not, however, observed following FGFR3 inhibition in MM cells with RAS mutations implicating RAS-MAPK in MIP-1 alpha regulation. As confirmation, inhibition of ERK1 also down-regulated MIP-1 alpha in FGFR3 inhibitor-resistant cells harboring RAS mutations. MIP-1 alpha is implicated in the survival and proliferation of MM cells and the pathogenesis of MM bone disease. Our observation is the first to directly link an initiating IgH translocation not only to MM-cell growth and survival but also to the disease-associated bone disease.

Design and structure–activity relationship of 3-benzimidazol-2-yl-1H-indazoles as inhibitors of receptor tyrosine kinases

3-Benzimidazol-2-yl-1H-indazole analogs were developed as inhibitors of receptor tyrosine kinases (RTK). The synthesis and SAR of this series is reported.

A phase 1, pharmacokinetic (PK) and pharmacodynamic (PD) study of CHIR-258, a novel oral multiple receptor tyrosine kinase (RTK) inhibitor

3043

Background: CHIR-258 is a potent small molecule inhibitor of VEGF, FGF, PDGF and c-KIT RTKs with IC50≤10nM that demonstrates activity in a variety of angiogenesis, tumour and metastasis models. Methods: Patients (pts) with histologically confirmed advanced solid tumors, ECOG PS 0–2 were treated in cohorts of 3–6 with CHIR-258. Treatment was as single daily doses on a repeated 7 days (d) on/7d off schedule (25–100mg), with a subsequent protocol amendment to continuous (cont) daily dosing. The objectives were to determine maximum tolerated dose (MTD) and dose limiting toxicity (DLT), evaluate PK and PD endpoints - ERK phosphorylation in PBL - and describe anti-tumour activity. Results: 35pts (median age 56.5 yrs; 15F/20M) were treated in 4 intermittent dosing cohorts (25, 50, 75, 100 mg/d) and 3 continuous dosing cohorts (100,125, 175 mg/d). The most common drug related adverse events were (grade [gr], number of pts): nausea (gr 1–3, 12); fatigue (gr 1–2, 9); headache (gr 1–3, 8); vomiting (gr 1–2, 7); anorexia (gr 1–2, 7); diarrhoea (gr 1–2, 6); dysgeusia (gr1–2, 6); anaemia (gr 2–3, 4); hypertension (gr 1–3, 3) and reversible asymptomatic drop in left ventricular ejection fraction (gr 2, 2). DLTs were gr 3 hypertension (HTN) in 1 pt with pre-existing HTN (100mg, cont); asymptomatic uncomplicated grade 2 elevation in cardiac troponin I (125mg); gr 3 anorexia/fatigue and gr 3 rise in alkaline phosphatase (both at 175mg). 3 pts have had prolonged stable disease (all 4m+; parotid, renal and imatinib-refractory GIST). The plasma PKs of CHIR-258 were linear over the dose range of 25–175 mg with respect to Cmax and AUC. On d1, the mean Cmax was 13.5(5.3) ng/mL to 109 (26) ng/mL, the mean AUC (0–24) was 224(97.4)ng*h/mL to 1740(466)ng*h/mL, and the t½ was 17h. Trough CHIR-258 concentrations at doses >50 mg/d were above the concentrations known to inhibit target receptor activation in vitro. Data on evaluable samples demonstrate up to 90% inhibition of basal ERK phosphorylation. Conclusions: CHIR-258 was safely administered at continuous daily doses up to 175mg/d. Modulation of p-ERK was demonstrated. Treatment is associated with disease stabilization.

[Table: see text]

Phase I trial of chir-258 in multiple myeloma

17502

Background: CHIR-258 is an orally active small molecule receptor tyrosine kinase (RTK) inhibitor which has potent activity against multiple RTKs involved in tumor growth and angiogenesis (IC50 ≤13 nM for FGFR, VEGFR, PDGFR, C-KIT, and FLT3). Approximately 15% of newly diagnosed MM patients harbor a t(4;14) translocation, which results in ectopic expression of FGFR3 and MMSET and is associated with poor treatment outcome [0]and reduced survival. CHIR-258 inhibits proliferation and induces apoptosis in FGFR3-expressing MM tumor xenografts as well as FGFR3-expressing primary MM cells (Trudel et al, Blood 2005). CHIR-258 was synergistic with dexamethasone (dex) in vitro. Methods: CHIR-258 was administered once daily in a dose-escalating phase 1 study to patients with relapsed/refractory MM. Drug tolerability and safety, pharmacokinetics (PK) and pharmacodynamics (PD) were assessed. Results: as of December 2005, 9 total pts have been treated (50, 100, and 200mg qd cohorts) [6M, 3F; median age: 58 (range: 44–68), median of 3 prior therapies(range:1–7)]. Prior tx: 9/9 pts-thalidomide; 8/9 -Velcade; 8/9-transplant; 8/9- had progressed through dex. 4 of 9 pts treated were FGFR3+ and 4 pts remain on study (3 are FGFR3+). No CR or PR have been observed; stable disease has been noted. CHIR-258 has been generally well tolerated, and most drug related AEs were CTC grade 1 or 2, including: headache, dysgeusia, fatigue and anorexia. No neuropathy. One DLT has been observed to date: neutropenia (200mg cohort). Five pts had dex added to CHIR-258 of which 3 are ongoing (all FGFR3+). FGFR3+ pts receiving dex and CHIR-258 have a greater decline in urine and serum paraproteins (pp) vs CHIR-258 alone. Plasma exposure and Cmax increased proportionally across the doses. Conclusions: CHIR-258 is a novel inhibitor of RTKs involved in MM growth and proliferation. FGFR3+ pts have a more marked reduction in pp than FGFR3- pts. CHIR-258 has generally been well tolerated and further accrual continues.

[Table: see text]

CHIR-258: A Potent Inhibitor of FLT3 Kinase in Experimental Tumor Xenograft Models of Human Acute Myelogenous Leukemia

PURPOSE

Fms-like tyrosine kinase 3 (FLT3) encodes a receptor tyrosine kinase (RTK) for which activating mutations have been identified in a proportion of acute myelogenous leukemia (AML) patients and associated with poor clinical prognosis. Given the relevance of FLT3 mutations in AML, we investigated the activity of CHIR-258, an orally active, multitargeted small molecule, with potent activity against FLT3 kinase and class III, IV, and V RTKs involved in endothelial and tumor cell proliferation in AML models.

EXPERIMENTAL DESIGN

CHIR-258 was tested on two human leukemic cell lines in vitro and in vivo with differing FLT3 mutational status [MV4;11 cells express FLT3 internal tandem duplications (ITD) versus RS4;11 cells with wild-type (WT) FLT3].

RESULTS

Antiproliferative activity of CHIR-258 against MV4;11 was approximately 24-fold greater compared with RS4;11, indicating more potent inhibition against cells with constitutively activated FLT3 ITD. Dose-dependent down modulation of receptor phosphorylation and downstream signaling [signal transducer and activator of transcription 5 (STAT5) and extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase] in MV4;11 cells with CHIR-258 confirmed the molecular mechanism of action. Target modulation of phospho-FLT3, phospho-STAT5, and phospho-ERK in MV4;11 tumors was achieved at biologically active doses of CHIR-258. Tumor regressions and eradication of AML cells from the bone marrow were shown in s.c. and bone marrow engraftment leukemic xenograft models. Tumor responses were characterized by decreased cellular proliferation and positive immunohistochemical staining for active caspase-3 and cleaved poly(ADP-ribose) polymerase, suggesting cell death was mediated in part via apoptosis.

CONCLUSIONS

Our data indicate that CHIR-258 may be an effective therapy in FLT3-associated AML and warrants clinical trials.

In vivoTarget Modulation and Biological Activity of CHIR-258, a Multitargeted Growth Factor Receptor Kinase Inhibitor, in Colon Cancer Models

PURPOSE

To evaluate the therapeutic and biological effects of CHIR-258, an orally bioavailable, potent inhibitor of class III-V receptor tyrosine kinases, in colon cancer models.

EXPERIMENTAL DESIGN

The pharmacologic activity of CHIR-258 was characterized by monitoring target modulation as well as by evaluating the antitumor and antiangiogenic effects in human colon xenograft models.

RESULTS

CHIR-258 inhibits vascular endothelial growth factor receptor 1/2, fibroblast growth factor receptor 1/3, and platelet-derived growth factor receptor beta (PDGFRbeta) and shows both antitumor and antiangiogenic activities in vivo. Treatment of KM12L4a human colon cancer cells with CHIR-258 resulted in a dose-dependent inhibition of vascular endothelial growth factor receptor 1 and PDGFRbeta phosphorylation and reduction of phosphorylated extracellular signal-regulated kinase (ERK) levels, indicating modulation of target receptors and downstream signaling. In vivo administration of CHIR-258 resulted in significant tumor growth inhibition and tumor regressions, including large, established tumors (500-1,000 mm(3)). Immunohistochemical analysis showed a reduction of phosphorylated PDGFRbeta and phosphorylated ERK in tumor cells after oral dosing with CHIR-258 compared with control tumors. These changes were accompanied by decreased tumor cell proliferation rate and reduced intratumoral microvessel density. CHIR-258 inhibited the phosphorylation of PDGFRbeta and ERK phosphorylation in tumors within 2 hours following dosing and the inhibitory activity was sustained for >24 hours. Significant antitumor activity was observed with intermittent dosing schedules, indicating a sustained biological activity.

CONCLUSION

These studies provide evidence that biological activity of CHIR-258 in tumors correlates with efficacy and aids in the identification of potential biomarkers of this multitargeted receptor tyrosine kinase inhibitor. CHIR-258 exhibits properties that make it a promising candidate for clinical development in a variety of solid and hematologic malignancies.

CHIR-258, a novel, multitargeted tyrosine kinase inhibitor for the potential treatment of t(4;14) multiple myeloma

The t(4;14) translocation that occurs uniquely in a subset (15%) of patients with multiple myeloma (MM) results in the ectopic expression of the receptor tyrosine kinase (RTK), fibroblast growth factor receptor 3 (FGFR3). Inhibition of activated FGFR3 in MM cells induces apoptosis, validating FGFR3 as a therapeutic target in t(4;14) MM and encouraging the clinical development of FGFR3 inhibitors for the treatment of these patients, who have a poor prognosis. We describe here the characterization of a novel, small-molecule inhibitor of class III, IV, and V RTKs, CHIR-258, as an inhibitor of FGFR3. CHIR-258 potently inhibits FGFR3 with an inhibitory concentration of 50% (IC50) of 5 nM in in vitro kinase assays and selectively inhibited the growth of B9 cells and human myeloma cell lines expressing wild-type (WT) or activated mutant FGFR3. In responsive cell lines, CHIR-258 induced cytostatic and cytotoxic effects. Importantly, addition of interleukin 6 (IL-6) or insulin growth factor 1 (IGF-1) or coculture on stroma did not confer resistance to CHIR-258. In primary myeloma cells from t(4;14) patients, CHIR-258 inhibited downstream extracellular signal-regulated kinase (ERK) 1/2 phosphorylation with an associated cytotoxic response. Finally, therapeutic efficacy of CHIR-258 was demonstrated in a xenograft mouse model of FGFR3 MM. These studies support the clinical evaluation of CHIR-258 in MM.

Hepatic arterial infusion of a replication-selective oncolytic adenovirus (dl1520): phase II viral, immunologic, and clinical endpoints

Replication-selective oncolytic adenoviruses are being developed for the treatment of cancer, but the safety and feasibility of repeated adenovirus delivery to tumors via the bloodstream was unknown, particularly in light of a patient death after hepatic artery infusion of a replication-defective adenovirus vector. We performed a Phase II trial of an oncolytic replication-selective adenovirus (dl1520, also known as Onyx-015) administered by hepatic artery infusion in patients with gastrointestinal carcinoma metastatic to the liver (n = 27). dl1520 was infused into the hepatic artery (2 x 10(12) particles) on days 1 and 8 as a single agent, and thereafter starting on day 22 in combination with i.v. 5-fluorouracil and leucovorin every 28 days. Repeated viral infusions were feasible, and no deaths occurred on study; reversible grade 3/4 hyperbilirubinemia occurred in 2 patients. Systemic inflammatory cytokine responses varied greatly between patients and even between cycles within a given patient. Proinflammatory cytokines [e.g., tumor necrosis factor, IFN-gamma, and interleukin (IL) 6] typically rose within 3 h and were followed at 18 h by a rise in IL-10. However, in the single patient who suffered a severe but reversible systemic inflammatory response, a unique cytokine profile was detected: marked acute increases of IL-6 (20-fold higher than average for all of the patients) and inhibition of IL-10 production. Delayed secondary peaks of viremia were reproducibly detected 3-6 days after treatment, even in the presence of high level neutralizing antibody titers and antiviral cytokines. Mathematical modeling was used to calculate the number of virus particles produced and shed into the blood with each replication cycle. The combination of virotherapy and chemotherapy had antitumoral activity in some chemotherapy-resistant colorectal tumors. The intra-arterial infusion of oncolytic adenoviruses warrants additional study.

Efficient induction of apoptosis by ONYX-015 adenovirus in human colon cancer cell lines regardless of p53 status

The ONYX-015 virus is a mutated adenovirus that in theory selectively replicates and induces cytolysis in tumor cells lacking functional p53. The present study investigated whether ONYX-015 viral infection alone or in combination with conventional chemotherapeutic agents could significantly increase apoptosis in human colon cancer cell lines, regardless of p53 status, compared to untreated cells. A pair of colon cancer cell lines that differ only in their p53 status (RKO with wild-type p53 and RKOp53 with deficient p53) was tested. Two chemotherapeutic agents, 5-fluorouracil (5-FU) and CPT-11, were tested in combination with ONYX-015. Final concentrations of these agents corresponded to peak plasma levels achievable in patients. ONYX-015 concentration was 10 p.f.u./cell. In RKO and RKOp53 cell lines, ONYX-015 viral infection alone or in combination with 5-FU or CPT-11 induced a significant increase in apoptosis compared to chemotherapeutic agents alone, regardless of p53 status. Moreover, the combination of ONYX-015 and chemotherapeutics induced more apoptosis than chemotherapeutics alone in the two colon cancer cell lines independently of their p53 status. We conclude that ONYX-015 virus infection alone or in combination with 5-FU or CPT-11 induced apoptosis in human colon cancer cell lines, independently of p53 status.

Unusual appearance of an en plaque meningioma of the cervical spinal canal. A case report and literature review

STUDY DESIGN

A case report of a patient with cervical spinal cord and nerve root compression caused by a meningioma en plaque together with calcification of the posterior longitudinal ligament is presented,with a review of the literature.

OBJECTIVE

To present the diagnosis of a calcified dural meningioma en plaque, with extradural extension into the ligamentum flavum, in a woman with cervical myelopathy and neuropathy.

SUMMARY OF BACKGROUND DATA

This case demonstrates that the cervical spine can be involved in dural meningioma en plaque with calcifications, in a manner mimicking ossification of the ligamentum flavum, which has never been previously reported.

METHODS

A patient presenting with cervical cord and nerve root compression caused by ossification of the posterior longitudinal ligament and a concurrent calcified dural meningioma en plaque was treated surgically and has made a gradual recovery. Imaging studies,surgical findings, and histopathologic evaluation were analyzed to support the diagnosis.

RESULTS

At surgery, ossification of the posterior longitudinal ligament was noted, along with a calcified lesion involving the posterior cervical dura and the adjacent ligamentum flavum. A calcified meningioma was diagnosed by histopathologic examination of the dural-based lesion.

CONCLUSION

Although previously not described, the diagnosis of calcified dural meningioma en plaque should be considered in all patients presenting with spinal cord and/or nerve root compression,even at cervical levels. Although ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum are more common etiologies of partially circumferential spinal calcification, dural-based meningiomas with extension into the surrounding ligaments demand early recognition because they can be associated with a poorer prognosis.

Safety and feasibility of injection with an E1B-55 kDa gene-deleted, replication-selective adenovirus (ONYX-015) into primary carcinomas of the pancreas: a phase I trial

Novel therapies are needed for locally advanced pancreatic carcinoma. ONYX-015 (dl1520) is an E1B-55 kDa region-deleted adenovirus that selectively replicates in and lyses tumor cells with abnormalities in p53 function (eg gene mutation). We carried out a phase I dose escalation study of ONYX-015 in patients with unresectable pancreatic cancer. ONYX-015 was administered via CT-guided injection (n = 22 patients) or intraoperative injection (n = 1) into pancreatic primary tumors every 4 weeks until tumor progression. Interpatient dose escalation was carried out with at least three patients per dose level from 10(8) p.f.u. up to the 10(11) p.f.u. dose level (two patients treated at this dose). The majority of patients had abnormally low cellular immunity (CD4 counts and hypersensitivity skin testing). Injection of ONYX-015 into pancreatic carcinomas was well-tolerated. Mild, transient pancreatitis was noted in only one patient. Dose-escalation proceeded to the highest dose level. Neutralizing antibodies rose post-treatment in all patients. After injection, ONYX-015 was detectable in the blood 15 min later, but not between 1 and 15 days later. Viral replication was not documented, however, in contrast to trials in other tumor types. No objective responses were demonstrated. Intratumoral injection of an E1B-55 kDa region-deleted adenovirus into primary pancreatic tumors was feasible and well-tolerated at doses up to 10(11) p.f.u. (2 x 10(12) particles), but viral replication was not detectable.

High-performance liquid chromatography/fluorescence detection of S-methylglutathione formed by glutathione-S-transferase T1 in vitro

Glutathione-S-transferase T1 (GSTT1-1) is a major isoenzyme for the biotransformation of halomethanes. The enzyme activity is located, among other places, in human liver and erythrocytes and is subject to a genetic polymorphism. Metabolism of the halomethanes via GSTT1-1 yields S-methylglutathione (MeSG). A new HPLC assay for the enzymatic formation of MeSG was developed. The glutathione conjugate was derivatized with 9-fluorenylmethyl chloroformate, followed by reverse-phase HPLC with gradient elution and fluorescence detection. The limit of detection was as low as about 39 pmol MeSG on-column. Including derivatization and HPLC analysis, samples could be run at 42-min intervals, thus enabling a high sample throughput. The entire method was validated for analyte recovery (78.2%) and for variations in detector response with replicated injections (11.8%) and with analyses on each of 11 consecutive days (15.2%) with erythrocyte lysate incubations as the matrix. The time-, protein-, and substrate-dependences of the enzymatic catalysis with the model substrates methyl bromide (MeBr) and methyl chloride (MeCl) were studied. Due to its strong electrophilic character, MeBr caused a high level of spontaneous MeSG formation from glutathione in a protein-free medium and a substrate-trapping side reaction in the presence of proteins. Therefore, enzymatic MeSG formation rates may only be determined with MeBr concentrations of at least 3000 ppm in the presence of limited amounts of protein (e.g. 100 microl erythrocyte lysate). In contrast, MeCl showed a lower alkylating potential allowing enzymatic catalysis to be the dominant reaction in incubations with 10,000 ppm MeCl and 2 ml erythrocyte lysate.

Efficacy with a replication-selective adenovirus plus cisplatin-based chemotherapy: dependence on sequencing but not p53 functional status or route of administration

Replication-selective adenoviruses are being developed as novel anticancer therapeutics. Clinical trials with dl 1520, an E1B-Mr 55,000 gene-deleted adenovirus (ONYX-015), have demonstrated selective viral replication and biological activity in head and neck and ovarian carcinomas, but durable objective responses were not demonstrated. However, clinical results suggested potentially synergistic interactions with platinum-containing chemotherapy. To better characterize and optimize this interaction, we carried out combined modality treatment with ONYX-015 and cisplatin-based chemotherapy in three nude mouse-human tumor xenograft models with differing tumor locations or p53 functional status. Superior efficacy was demonstrated with combination therapy over either agent alone in all three models, independent of the route of ONYX-015 administration (intratumoral or i.p.). Virus replication was not demonstrably inhibited by cisplatin plus 5-fluorouracil chemotherapy. To assess the role of p53 function or cisplatin resistance in this interaction, we treated ovarian carcinomas that were matched except for p53 functional status (A2780, A2780/CP70). Combination therapy led to improved survival over either agent alone in both the p53(-) and the p53(+) carcinomatosis models. Efficacy was highly dependent on the sequencing of the agents; treatment with ONYX-015 prior to, or simultaneously with, chemotherapy was significantly superior to chemotherapy followed by ONYX-015. These results support further evaluation of replication-selective adenoviruses and cisplatin-based chemotherapy in clinical trials.

Efficacy of a replication-selective adenovirus against ovarian carcinomatosis is dependent on tumor burden, viral replication and p53 status

Intraperitoneal (i.p.) recurrence of cisplatin-refractory and p53 mutant ovarian cancer is a major clinical problem, despite surgery and chemotherapy. dl1520 (ONYX-015) is an E1B-55 kDa gene-deleted adenovirus engineered selectively to replicate in and destroy cancer cells lacking functional p53. However, a correlation between efficacy and p53 function has not been definitively studied in vivo to date, and efficacy following i.p. administration had not been previously described. We therefore carried out experiments to address these issues in three nude mouse-human ovarian carcinomatosis xenograft models. Intraperitoneal treatment with dl1520 led to complete tumor eradication and/or significantly improved survival in two p53(-) nude mouse-human ovarian tumor xenograft models. OVCAR3 i.p. xenografts underwent complete regressions in 11 of 12 mice (versus one of seven controls; P = 0.001), while mice bearing cisplatin-resistant A2780 tumors had significantly improved survival versus controls (P = 0.05). In contrast, the A2780 p53(+) ovarian cancer xenograft was resistant to dl1520. The efficacy of i.p. dl1520 in the p53(-) models correlated strongly with tumor burden present at the time of treatment initiation, and no efficacy was seen with non-replicating/UV-inactivated dl1520. Selectively replicating viruses such as dl1520 hold promise as i.p. therapies for p53-deficient and chemotherapy-resistant ovarian carcinomas. A phase I clinical trial of i.p. dl1520 (ONYX-015) is underway in patients with cisplatin-resistant ovarian carcinoma.

An adenovirus E1A mutant that demonstrates potent and selective systemic anti-tumoral efficacy

Replication-selective oncolytic viruses constitute a rapidly evolving and new treatment platform for cancer. Gene-deleted viruses have been engineered for tumor selectivity, but these gene deletions also reduce the anti-cancer potency of the viruses. We have identified an E1A mutant adenovirus, dl922-947, that replicates in and lyses a broad range of cancer cells with abnormalities in cell-cycle checkpoints. This mutant demonstrated reduced S-phase induction and replication in non-proliferating normal cells, and superior in vivo potency relative to other gene-deleted adenoviruses. In some cancers, its potency was superior to even wild-type adenovirus. Intravenous administration reduced the incidence of metastases in a breast tumor xenograft model. dl922-947 holds promise as a potent, replication-selective virus for the local and systemic treatment of cancer.

a controlled trial of intratumoral ONYX-015, a selectively-replicating adenovirus, in combination with cisplatin and 5-fluorouracil in patients with recurrent head and neck cancer

ONYX-015 is an adenovirus with the E1B 55-kDa gene deleted, engineered to selectively replicate in and lyse p53-deficient cancer cells while sparing normal cells. Although ONYX-015 and chemotherapy have demonstrated anti-tumoral activity in patients with recurrent head and neck cancer, disease recurs rapidly with either therapy alone. We undertook a phase II trial of a combination of intratumoral ONYX-015 injection with cisplatin and 5-fluorouracil in patients with recurrent squamous cell cancer of the head and neck. There were substantial objective responses, including a high proportion of complete responses. By 6 months, none of the responding tumors had progressed, whereas all non-injected tumors treated with chemotherapy alone had progressed. The toxic effects that occurred were acceptable. Tumor biopsies obtained after treatment showed tumor-selective viral replication and necrosis induction.

A phase I study of Onyx-015, an E1B attenuated adenovirus, administered intratumorally to patients with recurrent head and neck cancer

An E1B 55 kDa gene-deleted adenovirus, Onyx-015, which reportedly selectively replicates in and lyses p53-deficient cells, was administered by a single intratumoral injection to a total of 22 patients with recurrent head and neck cancer. The objectives of this Phase I study were to determine the safety, feasibility, and efficacy of this therapy and determine any correlation to p53 status. Six cohorts were investigated with a dose escalation from 10(7)-10(11) plaque-forming units. Toxicity was assessed using NCIC criteria. Tumor response was assessed by clinical and radiological measurement. Blood samples were taken to detect adenovirus DNA and neutralizing antibody to adenovirus. Tumor biopsies were taken to detect adenovirus by in situ hybridization. Treatment was well tolerated, with the main toxicity being grade 1/2 flu-like symptoms. Dose-limiting toxicity was not reached at the highest dose of 10(11) plaque-forming units. Twenty-one of the 22 patients treated showed an increase in neutralizing antibody to adenovirus. In situ hybridization showed viral replication in 4 of 22 patients treated, all of whom had mutant p53 tumors. Using conventional response criteria, no objective responses were observed. However, magnetic resonance imaging scans were suggestive of tumor necrosis at the site of viral injection in five patients, three of whom were classified using nonconventional criteria as partial responders, and two of whom were classified using nonconventional criteria as minor responders. Of these five cases, four had mutant p53 tumors. The response duration for the three partial responders was 4, 8, and 12 weeks. An additional eight patients had stable disease in the injected tumors lasting from 4-8 weeks. These preliminary results show that intratumoral administration of Onyx-015 is feasible, well tolerated, and associated with biological activity. Further investigation of Onyx-015, particularly with a more frequent injection protocol and in combination with systemic chemotherapy, is warranted.

Interleukin-12 gene transfer results in CD8-dependent regression of murine CT26 liver tumors

BACKGROUND

Interleukin (IL)-12 has potent antitumor effects in animal models. We hypothesized that direct transfer of the IL-12 gene to established tumors would result in tumor regression without significant toxicity.

METHODS

Liver tumors were established by direct injection of CT26, a murine adenocarcinoma, into the livers of BALB/c mice, followed by three transfections with either murine IL-12, murine granulocyte-macrophage colony-stimulating factor, or luciferase cDNA using particle-mediated gene transfer. To assess the mechanism of this effect, immunohistochemical staining and depletion experiments with anti-CD4 or -CD8 antibodies were performed.

RESULTS

Progressive growth of primary tumors and carcinomatosis were present by day 16 after transfection with luciferase or murine granulocyte-macrophage colony-stimulating factor. At 50 days, complete regression of tumor was evident in seven of eight IL-12-treated mice (P < .001). In IL-12-transfected livers, immunohistochemical staining revealed an increase in CD8+ T cells. Selective depletion of CD4+ or CD8+ T cells was performed before and during transfection with murine IL-12. At 50 days, 75% of control mice were tumor-free. Only 46% of CD4+ cell-depleted mice (P = .143) and 7% of CD8+ cell-depleted mice (P < .001) were tumor-free.

CONCLUSIONS

IL-12 gene transfer using particle-mediated gene transfer results in complete regression of established CT26 liver tumors in 88% of mice; this effect is dependent on CD8+ T cells.

PTEN/MMAC1 is infrequently mutated in pT2 and pT3 carcinomas of the prostate

Deletion of the q23-24 region of human chromosome 10 is one of the most frequent genetic alterations in prostate cancer, suggesting that inactivation of a tumor suppressor gene in this region is involved in the development or progression of this carcinoma. A candidate gene, PTEN/MMAC1, has been identified from this chromosomal region; mutations of this gene have been found in various advanced tumors and cell lines including those of prostate cancer. To further define the role of PTEN/MMAC1 in the development of prostate cancer and its spectrum of genetic alterations, we analysed 40 pT2 or pT3 prostate tumors for allelic loss, mutations, and homozygous deletions using PCR-based methods. Six tumors showed loss of heterozygosity for one of the ten markers analysed, while one tumor showed loss of two markers. None of the markers within PTEN/MMAC1 was lost. Direct sequencing of PCR amplified exons and intron/exon junctions of all 40 tumors revealed three sequence variants, one of which was a point mutation in exon 9, while the other two were polymorphisms. Using multiplex PCR, no homozygous deletions were detected in any of the neoplasms. Our results showing a low frequency of alterations of PTEN/MMAC1 in pT2 and pT3 prostate cancers suggest that this gene plays an insignificant role in the development of most low stage carcinomas of the prostate.

Effects of chronic hormone replacement on the renin-angiotensin system in cynomolgus monkeys

OBJECTIVE

To characterize the effects of estrogen, estrogen combined with progestin, and no treatment in ovariectomized cynomolgus monkeys during long-term reproductive hormone replacement.

METHODS

Forty-five surgically postmenopausal cynomolgus monkeys fed a lipid-lowering diet were administered a conjugated equine estrogen (Premarin, 7.2 micrograms/day for the first 8 months, then 166 micrograms/day for the remaining 22 months), alone or in combination with 650 micrograms/day medroxyprogesterone acetate (Cycrin) for 30 months, or left with no hormone replacement therapy. Animals were anesthetized with ketamine-pentobarbital, and samples were taken for measurements of plasma renin activity, angiotensin converting enzyme activity, and angiotensin peptides, angiotensin I (Ang I), angiotensin II (Ang II), and angiotensin-(1-7) [Ang-(1-7)].

RESULTS

Chronic replacement therapy with estrogen resulted in a significant elevation of the plasma renin activity [11.7 +/- 2.0 ng/ml per h control versus 22.8 +/- 4.6 ng/ml per h with estrogen (P < 0.05) versus 32.8 +/- 4.9 ng/ml per h with combination therapy (P < 0.01)], whereas estrogen or combination therapy caused a significant reduction in angiotensin converting enzyme activity [229 +/- 8 nmol/ml per min control versus 189 +/- 10 nmol/ml per min with estrogen (P < 0.05) versus 196 +/- 11 nmol/ml per min with combination therapy (P < 0.05)]. Both of these changes in angiotensin processing enzymes observed during replacement therapy resulted in significant increases in plasma Ang I levels [46.7 +/- 12.5 pg/ml control versus 175.5 +/- 65.9 pg/ml with estrogen (P < 0.05) and 561.7 +/- 373.6 pg/ml with combination therapy (P < 0.05)]. Plasma Ang II and Ang-(1-7) levels were not significantly changed. The mean blood pressure did not change with either treatment.

CONCLUSION

These studies reveal that, although chronic estrogen replacement activates renin activity and Ang I, it causes a shift in the processing of angiotensin peptides such that the concurrent reduction in angiotensin converting enzyme activity leads to unchanged plasma Ang II levels. Thus, the potentially harmful effects of estrogen-induced hyperreninemia are balanced by its actions interfering with the formation of the vasoactive product Ang II.

ONYX-015, an E1B gene-attenuated adenovirus, causes tumor-specific cytolysis and antitumoral efficacy that can be augmented by standard chemotherapeutic agents

The 55-kilodalton (kDa) protein from the E1B-region of adenovirus binds to and inactivates the p53 gene, which is mutated in half of human cancers. We have previously shown that the replication and cytopathogenicity of an E1B, 55-kDa gene-attenuated adenovirus, ONYX-015, is blocked by functional p53 in RKO and U20S carcinoma lines. We now report that normal human cells were highly resistant to ONYX-015-mediated, replication-dependent cytolysis. In contrast, a wide range of human tumor cells, including numerous carcinoma lines with either mutant or normal p53 gene sequences (exons 5-9), were efficiently destroyed. Antitumoral efficacy was documented following intratumoral or intravenous administration of ONYX-015 to nude mouse-human tumor xenografts; efficacy with ONYX-015 plus chemotherapy (cisplatin, 5-fluorouracil) was significantly greater than with either agent alone.

Intraoperative monitoring of motor pathways during operative fixation of acute acetabular fractures

OBJECTIVE

To determine whether intra-operative spontaneous electromyography (EMG) was superior to somatosensory evoked potentials (SSEP) in the prevention of iatrogenic sciatic nerve injury.

DESIGN

Prospective, consecutive.

SETTING

Tertiary referral, teaching Hospital in New York City.

PATIENTS

Seventy-four patients with acutely displaced acetabular fractures.

MAIN OUTCOME MEASURE

Group A consisted of 24 patients who underwent intraoperative sciatic nerve monitoring using SSEP only. Group B consisted of 50 patients who underwent monitoring using both SSEP and spontaneous EMG. Motor potentials were recorded from the tibialis anterior, peroneus longus, abductor hallucis, and flexor hallucis longus muscles. All patients had independent preoperative and postoperative evaluations by the same neurologist.

RESULTS

One iatrogenic sciatic nerve injury occurred in group A and none in group B. Prolonged sciatic nerve compromise, demonstrated by significant intraoperative SSEP changes, occurred 2.4 times per case in group A and only 0.8 times per case in group B. In group B, spontaneous EMG noted compromise an average of 3.6 times per case (p < 0.0001).

CONCLUSIONS

The results of this study support spontaneous EMG as feasible and superior to SSEP monitoring in detecting intraoperative sciatic nerve comprise in acute acetabular fracture surgery. Spontaneous EMG permits earlier detection of intraoperative sciatic nerve comprise, allowing a more rapid response of the surgical team to noxious nerve stimuli. This may prevent permanent neurologic sequellae.