208 Calponin-targeting oncolytic Herpes simplex virus (HSV-1) as a novel therapeutic agent for sarcomatous mesothelioma

Sunday, October 22, 2006 / Poster Session: Novel agents/novel targets I and/or cellular anti-tumor immune responses in 8 of the 10 patients studied, including induction of anti- SV40 Tag antibodies. Recently, we initiated a second Phase 1 trial involving two doses of Ad.IFN beta vector administered 2 weeks apart, based upon preclinical data demonstrating superior efficacy with repeated dosing of Ad.IFN beta. Four patients with mesothelioma, and one with MPE secondary to metastatic non-small cell lung cancer, have been enrolled to date at two dose levels. No serious adverse events or dose limiting toxicities have been observed in the enrolled patients. Evaluation of clinical effects and anti-vector and anti-tumor immune responses are ongoing.

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Calponin-targeting oncolytic Herpes simplex virus (HSV-1) as a novel therapeutic agent for sarcomatous mesothelioma

K. Takahashi, H. Yamamura, R. Iuchi, J. Murai, N. Hirano, A. Tamura, K. Kodama. Osaka University, Osaka, Japan Background: Because of a lack of effective treatments, prognosis of sarcomatous mesothelioma remains poor. Calponin, a marker for smooth muscle cells, is transcriptionally up regulated in many human sarcomas (Yamamura et al. Cancer Res. 61; 3969-3977, 2001). Methods and Results: Using immunohistochemical, immunoblot or RT-PCR analyses with h1 or basic calponin, we demonstrated expression of calponin in 5 out of 7 cell lines and 6 out of 7 sarcomatous mesothelioma tissues, but not in reactive mesothelial cells. We generated a recombinant HSV-1 which was designed to replicate exclusively in calponin-positive cells. The viral immediateearly gene ICP4 was controlled by the calponin promoter. The LacZ-calponin promoter-ICP4-GFP transgene was inserted by homologous recombination into the ICP6 locus of an ICP4 null mutant. Since the ICP6 gene, encoding ribonucleotide reductase, is dispensable for viral replication in dividing cells but is required in non-dividing cells, the engineered HSV-1 lacking the functional ICP6 gene cannot replicate in non-dividing cells such as normal mesothelial cells. We observed potent cytopathic effects of the recombinant HSV-1 at 0.01–1.0 MOI on primary cultures from surgically resected calponin-positive malignant mesothelioma. For in vivo studies, 6 SCID mice harboring human malignant mesothelioma (mean volume 148 mm3 ) transfected with luciferase gene (pGL4.13) were treated three times intraneoplastically with either 1 x 107 PFU of the recombinant HSV-1 or virus buffer alone on days 25, 29 and 33 after xenograft transplantation. The viral treatment showed significant inhibition of tumor growth by day 36 as revealed by in vivo tumor imaging. Likewise, treatment with intrathoracic injection of 5 x 107 PFU resulted in stable and significant inhibition of tumor growth by day 36 after pleural transplantation of mesothelioma. Conclusions: Our results demonstrate for the first time that a calponintargeting oncolytic HSV-1, currently being purified in the GMP-grade, may provide novel therapeutic modality for malignant mesothelioma.

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S51

A comparison of CALGB and EORTC paradigms in the assessment of ONCONASE for the treatment of unresectable malignant mesothelioma (UMM)

J. von Pawel 1 , J.J. Costanzi 2 , S. Hardiman 3 . 1 Askleplos Fachkliniken Zentrum für Pneumologie and Thoraxchirurgie, Gauting, Germany; 2 Lone Star Oncology Consultants, Austin, USA; 3 ClinPro Inc. Background: ONCONASE® (ONC) a novel amphibian anti-neoplastic RNase, has been extensively studied in vitro and in vivo. ONC preferentially targets tRNA in exponentially growing cells; arrests cells in G1 phase of the cell cycle and induces apoptosis. ONC + Doxorubicin (Dox) vs. Dox is being evaluated in a randomized international Phase IIIb registration trial using CALGB groups as a stratification parameter. Methods: Kaplan Meier procedure was used to estimate MSTs. A comparison of the 6 CALGB Groups and the 5 variables of the EORTC paradigm [High (HR) vs. Low (LR) risk] was performed. CALGB group variables are performance status (PS), age, hemoglobin, WBC, weight loss, chest pain. EORTC paradigm variables are age, sex, histology, probability of diagnosis and PS, leukocyte count. Results: Phase III trial results: ONC vs. Dox (N=104) according to CALGB groups 1 to 4 (Chest 113:723, 1998) demonstrated a 2 month survival benefit (11.6 vs. 9.6) in favor of ONC (ASCO 2000). MST survival analysis (9/2006) showed no change. Majority of patients were epithelioid (EPI) histology, PS 1, CALGB Group 3. Survival analyses of treated patients showed: (Epi/ONC/30)/16.5 mos. (95% CI 300, 712) vs. (Epi/DOX/19)/13.6 mos. (95% CI 250, 703); (PS 1/ONC/27)/11.5 mos. (95% CI 200, 569) vs. (PS 1/DOX/18)/9.0 mos. (95%CI 182, 463); (Grp.3/ONC/26)/11.3 mos. (95% CI 227, 458) vs. (Grp.3/DOX/20)/8.9 mos. (95% CI 163, 414) EORTC survival analyses showed a six month difference [LR: (ONC/32)/15.0 mos. (95%CI 10, 24) vs. HR (ONC/11) 9.0 mos. (95%CI 3, 12), log rank p=0.0063] between the low and high risk groups. A two month difference [LR: (Dox/36)/10.0 mos. (95% CI 8, 15) vs. HR (Dox/18)/8.0 mos. (95%CI 5, 11), log rank p=0.3765] was observed for Dox. Conclusions: Prospective application of both paradigms effectively discriminates long vs. short term survivors. ONC is an effective agent for treatment of UMM. This research was sponsored by Alfacell Corporation.

Sunday, October 22, 2006 POSTER SESSION

Novel agents/novel targets I 209

Histone deacetylase inhibitors

S. Sharma. Nevada Cancer Institute, Las Vegas, USA Epigenetic modifications like histone acetylation are important for gene transcription. Histone deacetylase inhibitors (HDAIs) a novel class of anticancer agents in clinical trials, cause cancer-cell cytotoxicity by increasing gene transcription of cell cycle checkpoint, anti-angiogenesis and pro-apoptotic genes. HDAIs include hydroxamates like trichostatin A, suberoylanilide hydroxamic acid (SAHA) and LBH589, short chain fatty acids like butyrate, cyclic tetrapeptides like FR901228, benzamides like MS-275. Although there is much variation in chemical structure of HDAIs, they share certain common characteristics, including propensity to cause histone acetylation, induce cellular apoptosis in cancer cells (albeit by diverse mechanisms) and clinical activity in cutaneous T-cell lymphoma. In phase I trials with SAHA, single-agent activity was demonstrated in MM pts. A 660 pt phase III trial randomizes pts who have failed pemetrexed/platin to SAHA or placebo. Several trials examine HDAIs as chemo-sensitizers, including combinations of SAHA + cisplatin/pemetrexed, pemetrexed, and bevacizumab. A phase II trial of the HDAI PXD101 for MM has begun accrual. The molecular basis of activity of HDAIs is far from clear. Diverse sets of genes are activated, but another set of genes may also be silenced. The net effect of these influences on transcription translates into cellular growth arrest and apoptosis. In MM, there is evidence that there may be certain important genetic pathways e.g. cell cycle checkpoint, angiogenesis and apoptotic pathways that may be directly influenced by the HDAIs. HDAIs could enhance chemotherapyinduced effects on MM cells due to potentiation of cell cycle arrest, apoptosis and angiogenesis inhibition. HDAIs may cause decreases in oncoprotein activity directly or may influence broad post-translational processes by influencing heat shock-protein mediated chaperone pathways. Clearly, more work is required to clarify the molecular basis for sensitivity to HDAIs and clinical trials are needed to integrate them in treatment of MM.

211

Phase II trial of sorafenib (BAY 43-9006) in malignant mesothelioma: CALGB 30307

P.A. Jänne 1 , X.F. Wang 2 , L.M. Krug 3 , L. Hodgson 2 , E.E. Vokes 4 , H.L. Kindler 4 . 1 Dana Farber Cancer Institute, Boston, USA; 2 Duke University, Durham, USA; 3 Memorial Sloan Kettering Cancer Center, New York, USA; 4 University of Chicago, Chicago, USA Background: Systemic chemotherapy with cisplatin/pemetrexed is the approved first line treatment regimen for patients with malignant mesothelioma (MM). No standard of care exists for pts failing this therapy. In addition, many pts, especially those > 70, cannot tolerate combination chemotherapy. Angiogenesis inhibitors have emerged as attractive potential therapies for MM, and SU5416 and PTK787 have previously demonstrated single agent activity. We examined the efficacy of sorafenib, an inhibitor of VEGFR2, PDGFR-b and Braf, in chemotherapy naïve and previously treated MM pts. Methods: This was a single-arm phase II study of sorafenib in chemotherapy naïve and previously pemetrexed treated pts with MM. Primary end point was response rate (RR). Secondary objectives were 3-month failure free and overall survival (FFS and OS). Forty-four (44) eligible pts were expected to enroll to differentiate a RR of >20% versus <5%, with a Type I error of 0.0675 and a power of 0.955 Results: Between 10/04 and 8/05, 51 pts were enrolled and treated with sorafenib 400 mg bid. One cycle was 28 days; restaging occurred every 2 cycles. Baseline demographics: M/F (36/15); Median age (69; range 36-88; 45% > 70); Histology (epithelial/sarcomatoid/mixed/unknown: 37/4/8/2); pleural/peritoneal MM (46/5); ECOG PS 0/1 (11/40); chemo-naïve/prior chemo (20/31). Grade 3/4 toxicities occurring in >10% of patients: fatigue (12 (25%); 11/1) and handfoot reaction (6 (13%); 6/0). Estimates of RR and FFS are based on 43 pts with available follow-up data. Response. CR: 0; PR 2: 4.7% (95% CI; 0.6-15.8%); SD 17 (39.4%); PD 18 (41.9%); unevaluable 6 (14%). Three month FFS was 59%; median FFS was 4.1 months and median OS was 6.3 months. The me-