Publications

Human ovarian tumour-derived chaperone-rich cell lysate (CRCL) elicits T cell responses in vitro

Tumour-derived chaperone-rich cell lysate (CRCL), which is made up of numerous heat shock proteins, has been used successfully to generate tumour specific T cell responses and protective immunity against a wide range of murine tumours. In this study, we have investigated the potency of human ovarian cancer-derived CRCL to activate dendritic cells (DC) and to generate tumour-specific T cells in vitro. CRCL was generated from primary ovarian cancers and SKOV3-A2, a HER2/neu,Wilm’s tumour gene 1 (WT1) and human leucocyte antigen (HLA)-A2 positive human ovarian tumour cell line. Peripheral blood mononuclear cells from both HLA-A2+ healthy donors andHLA-A2+ ovarian cancer patients were stimulated weekly with autologous DC loaded with ovarian tumour-derived CRCL. After four to six stimulations in vitro, specific cytokine secretion and cytotoxicity were measured. CRCL promoted interleukin (IL)-12 secretion and enhanced the immunostimulatory capacity of DC. T cells from healthy controls and from ovarian cancer patients secreted higher amounts of interferon-g following in vitro restimulation with ovarian cancer-derived CRCL than with HER2/neu or WT1 peptide-pulsed DC. We were also able to generate cytotoxic T lymphocyte activity against cancer specific antigens such as HER2/neu andWT1fromall healthy donors, but from only one of the four ovarian cancer patients with bulky disease. These preliminary results substantiate further the concept that CRCL may prove to be a potent adjuvant for women suffering from ovarian cancer and that this personalized vaccine may be a promising approach for active immunotherapy.

Completely mismatched allogeneic CD3/CD28 cross-linked Th1 memory cells elicit anti-leukemia effects in unconditioned hosts without GVHD toxicity

Fully allogeneic CD3/CD28 cross-linked Th1 cells were found to elicit host-mediated anti-leukemia effects without GVHD toxicity. Mice inoculated with a lethal dose of BCL1 leukemia demonstrated significantly enhanced survival after allogeneic Th1 treatment. Cure rates of 12.5% with a single allogeneic cell infusion and 31.25% with multiple infusions were demonstrated. Cured mice were able to reject rechallenge with a lethal dose of tumor without further treatment. These results suggest that use of intentionally mis-matched, Th1 memory cells infused with cross-linked CD3/CD28 could represent a novel clinical approach to eliciting potent anti-tumor effects in patients without conditioning and without GVHD toxicity.
© 2008 Elsevier Ltd. All rights reserved.

The anti-tumor effect of allogeneic bone marrow/ stem cell transplant without graft vs. host disease toxicity and without a matched donor requirement?

The anti-tumor immune response that occurs in allogeneic bone marrow/stem cell transplant (BMT) settings is capable of eradicating tumors that are resistant to chemotherapy/radiation treatment. This anti-tumor immune response, known as the graft vs. tumor (GVT) effect, is the most effective immunotherapy treatment ever discovered. Unfortunately, the clinical application of GVT is severely limited due to the intimate association of GVT with the extremely toxic and often lethal side-effect known as graft vs.

Completely mismatched allogeneic CD3/CD28 cross-linked Th1 memory cells elicit anti-leukemia effects in unconditioned hosts without GVHD toxicity

Fully allogeneic CD3/CD28 cross-linked Th1 cells were found to elicit host-mediated anti-leukemia effects without GVHD toxicity. Mice inoculated with a lethal dose of BCL1 leukemia demonstrated significantly enhanced survival after allogeneic Th1 treatment. Cure rates of 12.5% with a single allogeneic cell infusion and 31.25% with multiple infusions were demonstrated. Cured mice were able to reject rechallenge with a lethal dose of tumor without further treatment. These results suggest that use of intentionally mis-matched, Th1 memory cells infused with cross-linked CD3/CD28 could represent a novel clinical approach to eliciting potent anti-tumor effects in patients without conditioning and without GVHD toxicity.
© 2008 Elsevier Ltd. All rights reserved.

Heat shock proteins and cancer vaccines: developments in the past decade and chaperoning in the decade to come

Molecular chaperone–peptide complexes extracted from tumors (heat shock protein [HSP] vaccines) have been intensively studied in the preceding two decades, proving to be safe and effective in treating a number of malignant diseases. They offer personalized therapy and target a cross-section of antigens expressed in patients' tumors. Future advances may rely on understanding the molecular underpinnings of this approach to immunotherapy. One property common to HSP vaccines is the ability to stimulate antigen uptake by scavenger receptors on the antigen-presenting cell surface and trigger T-lymphocyte activation. HSPs can also induce signaling through Toll-Like receptors in a range of immune cells and this may mediate the effectiveness of vaccines.

IMATINIB MESYLATE EFFECTIVELY COMBINES WITH CHAPERONE-RICH CELL LYSATE-LOADED DENDRITIC CELLS TO TREAT bcr-abl MURINE LEUKEMIA

Imatinib mesylate has become an effective agent for the treatment of chronic myeloid leukemia (CML). However, the development of drug resistance has led to examination of combination therapies. In this study, we investigated the effects of combining imatinib with immunotherapy against a murine bcr-abl leukemia, 12B1. We have previously shown that multiple chaperone proteins may be enriched into a vaccine form from tumor cell lysates by a free-solution isoelectric focusing method. We refer to these vaccines as chaperone-rich cell lysates (CRCLs) and have found that they are potent immunologic agents against a variety of murine tumors, including 12B1. We now demonstrate that the combination of imatinib with dendritic cells loaded with 12B1- derived CRCL yields high activation of anti-12B1-specific T cells and potent antitumor activity, resulting in tumor-free survival in up to 63% of mice with bcr-abl 12B1 tumors. Our data suggest that immunotherapy can be effectively combined with imatinib for the treatment of CML.
© 2004 Wiley-Liss, Inc.

Signaling pathways induced by a tumor-derived vaccine in antigen presenting cells

We have previously reported on the anti-tumoral potential of a chaperone-rich cell lysate (CRCL) vaccine. Immunization with CRCL generated from tumors elicits specific T and NK cell-dependent immune responses leading to protective immunity in numerous mouse tumor models. CRCL provides both a source of tumor antigens and danger signals leading to dendritic cell activation. In humans, tumor-derived CRCL induces dendritic cell activation and CRCL-loaded dendritic cells promote the generation of cytotoxic T lymphocytes in vitro. The current study was designed to identify the signaling events and modifications triggered by CRCL in antigen presenting cells. Our results indicate that tumor- derived CRCL not only promotes the activation of dendritic cells, but also significantly fosters the function of macrophages that thus appear as major targets of this vaccine. Activation of both cell types is associated with the induction of the MAP kinase pathway, the phosphorylation of STAT1, STAT5 and AKT and with transcription factor NF-kB activation in vitro and in vivo. These results thus provide important insights into the mechanisms by which CRCL based vaccines exert their adjuvant effects on antigen presenting cells.

 

Induction of BCR-ABL–specific immunity following vaccination with chaperone-rich cell lysates derived from BCR-ABL tumor cells

We have previously reported that chaperone rich cell lysates (CRCL) derived from the BCR-ABL 12B1 leukemia activate dendritic cells (DCs) and stimulate leukemia-specific immune responses. Because CRCL contain a variety of heat shock/chaperone proteins, we theorized that CRCL obtained from BCRABL leukemias are likely to chaperone BCR-ABL–derived fusion peptides and that DCs pulsed with 12B1 CRCL could crosspresent BCR-ABL fusion peptides to T cells. We found that splenocytes from mice vaccinated with BCR-ABL leukemia-derived CRCL secreted interferon- (IFN-) when restimulated with a BCR-ABL peptide, GFKQSSKAL, indicating that BCR-ABL peptides are chaperoned by leukemia-derived CRCL. We next eluted peptides from 12B1leukemia-derived CRCL and used high pressure liquid chromatography (HPLC) fractions to restimulate splenocytes harvested from mice vaccinated with DC/GFKQSSKAL or DC/12B1 CRCL. We found that the same peptide fractions derived from 12B1 CRCL and from “refractionated” GFKQSSKAL stimulated IFN- production, suggesting the presence of BCR-ABL peptides in the peptide repertoire of 12B1 CRCL. We also demonstrated that immunization with DCs loaded with leukemia-derived CRCL induced BCR-ABL–specific cytotoxic T lymphocytes (CTLs) in vivo. Moreover, mice immunized with DCs pulsed with 12B1-derived CRCL had superior survival (60%) when compared with those immunized with DCs pulsed with BCR-ABL peptide (20%), indicating that CRCL vaccines provide additional immune stimulus over and above individual peptide vaccination.

(Blood. 2005;105:2016-2022)

Chaperone-rich tumor cell lysate-mediated activation of antigen-presenting cells resists regulatory T cell suppression

Abstract: CD4CD25 regulatory T cell lymphocytes (Tregs) critically contribute to the mechanisms of cancer-induced tolerance. These cells suppress anti-tumoral CD8 and CD4 T lymphocytes and can also restrain the function of APCs. We have previously documented the immunostimulatory effects of a chaperone-rich cell lysate (CRCL) anti-cancer vaccine. Tumor-derived CRCL induces tumor immunity in vivo, partly by promoting dendritic cell (DC) and macrophage activation. In the current study, we evaluated the effects of CD4CD25forkhead box P3 Tregs isolated from mice bearing 12B1 bcr-abl leukemia on DC and macrophages that had been activated by 12B1-derived CRCL, and CRCL-activated DC and macrophages resisted Treg suppression, as the production of proinflammatory cytokines, the activation of transcription factor NF-B, and their immunostimulatory potential was unaffected by Tregs. Our results thus highlight CRCL as a powerful adjuvant endowed with the capacity to overcome tumor-induced Treg-inhibitory effects on APCs. J. Leukoc. Biol. 83: 000–000; 2008.

Molecular Cancer Therapeutics

A chaperone protein-enriched tumor cell lysate vaccine generates protective humoral immunity in a mouse breast cancer model.

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SPECIALITY INFORMATION

patients


Treatment strategy designed to use the power of the human immune system to kill tumors and prevent their recurrence.
No requirement for a matched donor or chemotherapy/radiation conditioning prior to treatment.
Innovative technology – proven and non-toxic.
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Therapeutic anti-tumor vaccine developed from core break-through technology called the "Mirror Effect™“ which opens a pathway to treating patients with metastatic cancer that have failed all available therapy options.
Elicits a GVT-like mechanism without the GVHD toxicity.
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Privately-held Israeli biopharmaceutical company spin out from Hadassah-Hebrew University Medical Center with headquarters in Jerusalem.

Over 200 individual private shareholders and grant support from the Israel Office of the Chief Scientist.
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