The purpose of this application is to foster the career development of Dr. Dung Le. Dr. Le's primary interest is in immunotherapy for gastrointestinal cancers. Specifically, she is developing a translational research program testing novel vaccine platforms and strategies that combine immune targeted agents to train the immune system to recognize and attack cancers. Dr. Elizabeth Jaffee will serve as her primary mentor. Dr. Jaffee's depth of experience in pancreatic adenocarcinoma (PDA) immunotherapy research makes her an ideal mentor. The career development plan will be composed of a mentorship plan, an advisory committee, and a formal didactic curriculum. In addition, Dr. Le will be actively conducting research. The research proposal aims to test the hypothesis that there is an association between in vivo immune responses and clinical responses in patients with metastatic PDA treated with immunomodulatory doses of cyclophosphamide (Cy) in sequence with a priming allogeneic GM-CSF transfected pancreatic tumor vaccine (GM-CSF vaccine) followed by boosting with a Listeria (Lm) vaccine containing mesothelin (CRS-207). Previously, Dr. Jaffee has shown in phase I and II studies that the GM-CSF vaccine enhances survival and this survival benefit correlates with the induction of T cells specific for mesothelin, a PDA antigen. In addition, immune modulating doses of Cy to deplete regulatory T cells in patients with advanced PDA induces higher avidity T cell responses which are also associated with improved overall survival (OS). In immune tolerant cancers, such as PDA, combination strategies will be necessary to improve anti-tumor immunity. Pre-clinical studies demonstrate that the combination of GM-CSF and Listeria (Lm)-based vaccines in a heterologous prime/boost regimen results in the induction of T cell responses of greater magnitude than either agent alone, and in superior anti-tumor responses. Dr. Le completed the phase I testing of CRS-207 which is a live-attenuated strain of Lm that expresses mesothelin. This approach works by facilitating antigen presenting cells (APCs) to simultaneously receive the """"""""danger"""""""" signals necessary for proper maturation and efficient delivery of the antigen into both class I and class I processing pathways, while also stimulating innate immunity. CRS-207 administration results in the induction of mesothelin and Lm-specific T cell responses, cytokine responses, and NK cell activation. In the phase I study, 6 of 17 subjects survived for e 15 months. This proposal will build on experiences with the clinical development of two distinct, but complementary vaccines.
The specific aims are to: recruit 90 subjects with metastatic PDA who have failed standard therapy into a 2 arm study testing Cy in sequence with a GM-CSF vaccine followed by CRS-207 or Cy in sequence with a GM-CSF vaccine alone;assess for safety;measure the association of specific in vivo parameters of immune response such as mesothelin-specific T cell responses with clinical responses;and estimate clinical responses by assessing OS, response rate, and tumor marker kinetics. The success of this proposal would have a significant impact on patients with PDA.
Novel strategies are desperately needed for the treatment of pancreatic adenocarcinoma. This proposal will test an immunotherapy strategy that combines immune modulating doses of cyclophosphamide with a GM- CSF cell based vaccine and a Listeria-monocytogenes based vaccine. This study is based on strong scientific rationale and interesting preliminary clinical data and will assess for both immunologic and clinical responses to the combination.
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