The breast cancer susceptibility gene 1 (Brca1) has a key role in both hereditary and sporadic mammary tumorigenesis. However, the reasons why Brca1-deficiency leads to the development of cancer are not clearly understood. Activation of Akt kinase is one of the most common molecular alterations associated with human malignancy. Increased Akt kinase activity has been reported in most breast cancers. We previously found that downregulation of Brca1 expression or mutations of the Brca1 gene activate the Akt oncogenic pathway. To further investigate the role of Brca1/Akt in tumorigenesis, we analyzed Brca1/Akt expression in human breast cancer samples and found that reduced expression of Brca1 was highly correlated with increased phosphorylation of Akt. Consistent with the clinical data, knockdown of Akt1 by short-hairpin RNA inhibited cellular proliferation of Brca1 mutant cells. Importantly, depletion of Akt1 significantly reduced tumor formation induced by Brca1-deficiency in mice. The third generation inhibitor of mammalian target of rapamycin (mTOR), Palomid 529, significantly suppressed Brca1-deficient tumor growth in mice through inhibition of both Akt and mTOR signaling. Our results indicate that activation of Akt is involved in Brca1-deficiency mediated tumorigenesis and that the mTOR pathway can be used as a novel target for treatment of Brca1-deficient cancers.

2032 Background: Previous immunotherapy trials for malignant glioma (Yu, J.,et al, Cancer Res. 2001;61:842–7 and 2004;64;4973–9) have demonstrated efficacy in generating a tumor specific immune response. Here we set out to determine feasibility and immunogenecity of dendritic vaccination with specific glioma-associated antigens. Methods: The goal of this study is to use tumor associated antigens (TAA) known to be expressed on gliomas and pulse dendritic cells with these antigens in an MHC compatible fashion using epitopes of HER-2, TRP-2, gp100, MAGE-1, IL13R alpha, and AIM-3. In this phase I trial, HLA-A1 and/or HLA-A2-positive patients with newly diagnosed or recurrent glioblastoma were eligible. Leukapheresis was used to isolate mononuclear cells which were differentiated into dendritic cells in culture, pulsed with tumor peptide, and then administered intradermally three times at 2-week intervals. Results: Twenty patients, 15 males and five females, were enrolled between November 2006 and December 2008 with one screen failure. The median patient age was 47 years (range: 26–65) and patients had a median Karnofsky performance status of 90% (range: 90–100). There were 16 newly diagnosed and three recurrent glioblastoma multiforme (GBM) patients, who underwent surgery prior to vaccination. Our data on 19 patients and 54 courses of dendritic cell vaccines demonstrate zero grade 3 /4 toxicities that were attributable to the vaccination. Thirteen patients continue to have stable disease (ranging from 15 to 115 weeks), six patients have demonstrated tumor progression. Median survival from surgery was 60 weeks (ranging from 26 to 115 weeks). Of 15 patients tested to date, six patients demonstrated an antigen-specific cytotoxic T-cell response to at least one antigen after vaccination. Only 17% of CTL responders (1/6) demonstrated tumor progression compared to 56% (5/9) of nonresponders to date. Conclusions: This phase I study demonstrated the feasibility, safety, and bioactivity of a TAA-pulsed dendritic cell vaccine for patients with glioblastoma progression free survival correlated with CTL response. [Table: see text]

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2033 Background: Our prior immunotherapy trials demonstrated efficacy in generating a tumor specific immune response in malignant glioma and the potential for high tumor-specific toxicity and sustained tumoricidal activity. Immunotherapy may synergize with chemotherapy and biodegradable carmustine (BCNU) wafers extend overall survival from 11.6 to 13.9 months. Methods: We exploited this synergistic effect to maintain a cytotoxic environment around the tumor milieu. Patients with high-grade glioma were eligible after maximal resection with biodegradable carmustine (BCNU) wafer placement. Screening leukapheresis is used to isolate mononuclear cells which are differentiated into dendritic cells, pulsed with tumor lysate, and then 3 intradermal vaccines are administered at 2-week intervals. Patients continued systemic chemotherapy after vaccine or at progression. Results: Eighteen patients have been enrolled (7 Male, 11 Female) between April 2007 and February 2009 with one screen failure and two patients with clinical progression prior to vaccination. The median patient age was 57 years (26 to 74 ) and median Karnofsky performance status was 90% (80–100). The histology included 3 newly diagnosed glioblastoma multiforme (GBM), 8 recurrent GBM, 2 newly diagnosed anaplastic astrocytoma (AA), and 2 recurrent AA. 15 patients were successfully treated by vaccine injections with 12 patients receiving vaccine every 2 weeks x 3 followed by adjuvant chemotherapy. Our preliminary data on 15 patients and 39 courses of Dendritic Cell vaccines demonstrate one grade 3 toxicity of fever/chest pain. A stable disease interval of 13 to 90 weeks was observed for patients who received vaccine. The 3 newly diagnosed GBM patients have stable disease (18 to 71 weeks). In the recurrent GBM cohort 7/8 patients had progression within 6 months from the post-vaccination MRI. Conclusions: This phase I study demonstrates the safety, feasibility of dendritic cell vaccination with biodegradable carmustine (BCNU) wafers with one grade 3 AE. Immunological data is pending to determine potential synergy of dendritic cell vaccination with intracranial chemotherapy. No significant financial relationships to disclose.