Douglas G. McNeel - US grants

DESCRIPTION (provided by applicant): Dr. McNeel will develop a career in patient-oriented translational research with an emphasis on the immunological treatment of patients with prostate cancer. The goal of this proposal is describe both a career training and mentoring plan through which he will receive training in the proper conduct of human subjects research, as well as a translational research plan leading to the conduct of a human vaccine trial for patients with prostate cancer. As part of his career development plan, Dr. McNeel will complete the UW Clinical Investigator Preparatory Pathway (CIPP). This program is an individualized program proviiding didactic and mentored training in the areas of biostatistics and clinical study design, clinical research ethics, leadership and management skills, presentation and teaching skills, scientific writing skills, and expertise within a specific research domain. In addition, he will be mentored directly by Dr. Mark Albertini, a leader in the field of DNA vaccien clinical trials research. His academic and career progress will be followed quarterly by the CIPP Executive Committee as well as Dr. McNeel's faculty mentoring committee at the University of Wisconsin (composed of Drs. Albertini, Sondel, Bryan and Bailey). The other part of this proposal describes a 5-year translational research plan in which Dr. McNeel proposes three aims: 1) to identify the immunological mediators of prostate tissue destruction in a rat model fo inflammatory prostatistics; 2) to identify proteins immunologically recognized in patients with chronic inflammatory prostatis; and 3) to determine in a human clinical vaccine trial the safety and immunological efficacy of a DNA-based vaccine in patients with advanced stage prostate cancer. This clinical trial will target the same antigen, prostatic acid phosphatase, and using the same DNA immunization techniques used to elicit prostatis in the rodent model. This trial will serve as a platform and model for clinical trial evaluation of antigens identified in the second aim of the proposal.

DESCRIPTION (provided by applicant): The University of Wisconsin-Madison has had a T32 program for Physician Scientist Training in Cancer Medicine since 1988. The purpose of this program has been to train physicians in laboratory-oriented research to prepare them for independent academic careers in cancer-focused medicine. This has been in response to a national problem of declining numbers of physician scientists entering research-related careers over the last three decades. The past success of our program can be judged by the numbers of our trainees who have continued in academic research-related careers. Over the 1993-2003 decade of funding, 19 of 26 (73%) trainees are in academic faculty positions. Since 2003, nearly all of our trainees continue in training for future academic careers. The current application requests support to continue this program, and describes our efforts to further improve on our past success with regards to training, monitoring outcomes, and our efforts to recruit trainees of diverse and underrepresented ethnic and cultural backgrounds. Our specific aim is to develop physicians as scientists with a strong foundation in basic and translational cancer research to help prepare them for careers in academic medicine. RELEVANCE: There is a national shortage of physician scientists. This grant trains physicians in cancer research from specialties such as medical oncology, hematology, gastroenterology, pediatric oncology, and radiation oncology to developing laboratory/translational academic careers. Thus, this training is highly relevant to the mission of the National Cancer Institute.

DESCRIPTION (provided by applicant): Prostate cancer is a significant worldwide health problem for which new treatments are needed. The goal of this research is to develop anti-prostate tumor vaccines as a treatment for cancer, and specifically prostate cancer. Our laboratory has been seeking to define appropriate antigens for inclusion in prostate cancer vaccines, target these antigens in rodent models using plasmid DNA vaccines, and ultimately to translate these findings to human clinical testing in patients with prostate cancer. We and other investigators have focused our initial efforts on prostatic acid phosphatase (PAP) as a prostate tumor vaccine antigen. We have previously demonstrated in rats that DNA vaccines encoding either human or rat PAP can elicit PAP-specific CD4+ and CD8+ T-cell responses, IFN? secreting responses, and antibody responses. Moreover, we have shown that CD4+ and CD8+ T-cells specific for PAP can be detected in patients with prostate cancer, suggesting that immunological tolerance to this protein can be circumvented in vivo in humans. We have also investigated a plasmid DNA vaccine encoding PAP in a dose-escalation phase I clinical trial in patients with recurrent non-metastatic prostate cancer. In that trial we observed no significant adverse events, demonstrated immunological efficacy in augmenting PAP-specific CD8+ T-cells, and observed an increase in PSA doubling time in several patients. Questions remain, however, as to the optimal frequency of immunization to maintain long-term effector and memory T-cell responses, and whether the development of these long-term responses will result in improved clinical outcomes. The goal of the current protocol will be to evaluate the safety and immunological efficacy of this same plasmid DNA vaccine, administered over a prolonged period of time with booster immunizations given at regular intervals or as defined by ongoing immune monitoring, to induce and/or augment CD8+ T-cell effector and memory immune responses to PAP in patients with castrate-resistant, non-metastatic prostate cancer. One cohort of subjects will be treated with six bi-weekly immunizations, as previously conducted, with immunizations continuing at regular 3-month intervals. The other cohort will be treated with six bi-weekly immunizations followed by booster immunizations at a schedule defined by the presence or absence of PAP-specific T-cell responses. This will be a small, randomized phase II trial design with fifteen subjects per cohort, powered to detect an immune response rate of 80% at one year after study initiation. The study design will permit an indirect comparison with our previous study with respect to immune response rates, and will have the goal of identifying an optimal approach for phase II clinical trial testing. Given that previous studies conducted by us and others have suggested that the induction of immune responses to PAP may be associated with clinical benefit in the treatment of prostate cancer, secondary endpoints will be to evaluate the effect on PSA doubling time and 1-year metastasis-free survival. The specific aims of the proposed clinical trial will be 1) to determine the safety of serial intradermal vaccinations of a DNA vaccine encoding PAP, with GM-CSF as a vaccine adjuvant, in patients with non-metastatic castrate-resistant prostate cancer;2) to determine whether PAP-specific IFN?-secreting CD8+ T-cells and long-term antigen-specific memory CD8+ T-cells can be elicited in patients with non-metastatic castrate-resistant prostate cancer by means of immunization with a plasmid DNA vaccine encoding PAP;and 3) to determine if antigen-specific effector and memory T-cells can be augmented by using individualized schedules of booster immunizations determined by immunological monitoring. PUBLIC HEALTH RELEVANCE: Prostate cancer is a significant worldwide health problem, and the second leading cause of cancer-related death in men in the United States. Patients with rising serum PSA after androgen deprivation therapy are at high risk for developing progressive, metastatic disease. The goal of this research is to develop effective anti-tumor DNA vaccines as a treatment for prostate cancer, and to specifically evaluate a vaccine in a clinical trial for patients with this stage of prostate cancer. Thus, this proposal is directly relevant to the mission of the National Cancer Institute, and directly relevant to this specific Program Announcement. In addition, the goal of this proposal is to determine if immune monitoring can be used to guide the ongoing schedule of treatment with a vaccine, to ultimately define an optimal schedule of treatment. This is consequently relevant to the development of other anti-tumor vaccines.

DESCRIPTION (provided by applicant): Prostate cancer is a significant worldwide health problem for which new treatments are needed. The goal of our research is to develop effective active immunotherapies, tumor vaccines, as a treatment for prostate cancer. In this application we propose to evaluate a novel immunotherapy target antigen, the ligand-binding domain of the androgen receptor (AR LBD), a biologically relevant molecule to prostate cancer growth and progression. We have previously demonstrated that patients with prostate cancer have existing humoral and cellular immune responses specific for the AR LBD, and that cytolytic CD8+ T cells specific for the AR LBD can lyse human prostate cancer cells in an HLA-A2 MHC class I-restricted fashion. In addition, we have demonstrated that a DNA vaccine encoding the AR LBD can elicit epitope-specific CD8+ T cells in an HLA-A2 transgenic mouse. Moreover, we have previously shown that increased expression of Hsp72 can increase MHC class I expression and antigen presentation. In the current proposal we hypothesize that a DNA vaccine encoding the AR LBD can elicit peptide- specific anti-tumor immune responses, and that modifications to a DNA vaccine permitting increased antigen presentation can augment anti-tumor immune responses. This will be evaluated in HLA-A2 transgenic mice, and in an HLA-A2-expressing transgenic mouse model of prostate cancer. For all of these studies we will focus on the ligand-binding domain (LBD) of the protein only, and will use the generation of responses to specific HLA-A2 epitopes as a read-out for immunological efficacy, markers which can be similarly used in a human clinical trial. In addition, we will evaluate whether DNA vaccines encoding hsp72 and/or a proteasome-targeting signal within a DNA vaccine can augment antigen presentation and antigen-specific cytolytic T- cell (CTL) responses, and anti-tumor immune responses in vivo. Finally, based on these results, we will conduct a phase I clinical trial to evaluate the safety and immunological efficacy of a DNA vaccine encoding the AR LBD, with or without modifications to facilitate antigen presentation, in patients with castrate-resistant, nonmetastatic prostate cancer. The specific aims of the proposal will be: 1) to determine whether a DNA vaccine encoding the AR LBD can elicit antigen-specific CD8+ T-cells and anti-prostate tumor responses in HLA-A2 transgenic mice;2) to determine whether co-expression of Hsp72 or a proteasome-targeting signal with a model antigen in the context of a DNA vaccine can augment antigen-specific CD8+ T-cell effector immune responses and anti-tumor responses in HLA-A2-expressing transgenic mice;and 3) to determine the safety and immunological efficacy of a DNA vaccine encoding the AR LBD, with or without co-expression of Hsp72 and/or a proteasome-targeting signal, in patients with castrate-resistant nonmetastatic prostate cancer. PUBLIC HEALTH RELEVANCE: Prostate cancer is a significant worldwide health problem, and the second leading cause of cancer-related death in men in the United States. New treatments for prostate cancer are urgently needed. The goal of this research is to develop effective anti-tumor DNA vaccines as a treatment for cancer, and prostate cancer in particular. Thus, this proposal is directly relevant to the mission of the National Cancer Institute. This proposal will characterize and evaluate a new vaccine target antigen in prostate cancer, the ligand binding domain of the androgen receptor. The androgen receptor has been the key pharmacological target for metastatic prostate cancer treatment for over 50 years, but there has been no previous evaluation of this as an immunological target antigen. In addition, our project seeks to identify means of increasing the efficacy of DNA vaccines by increasing presentation of the target antigen at the time of immunization. As such the results from these studies should be widely applicable to other genetic vaccines. Finally, this proposal will evaluate these findings in a human clinical trial in patients at high risk for prostate cancer metastatic recurrence.

Prostate cancer is a significant global health concern for which new treatments are needed. The long-range goal of our research for nearly two decades has been to develop active immunotherapies, and tumor vaccines in particular, as treatments for prostate cancer. We have focused on DNA vaccines as a simple method, and one specifically aimed at generating tumor antigen-specific CD8 T cells. A major effort in our laboratory over the last several years has been to evaluate the tumor response to immunization and identify mechanisms of resistance to immunization. We have found that PD-1 or LAG-3 are upregulated after T cell activation with vaccination, and that even the transient expression of PD-1 or LAG-3 following antigen-specific T-cell activation is sufficient to allow them to be regulated in the immunosuppressive tumor environment, and this can be abrogated using concurrent blockade of PD-1 or LAG-3. We have recently demonstrated that this is true in humans as well, as delivery of a PD-1 blocking antibody (pembrolizumab) at the time of immunization with a DNA vaccine, rather than beginning weeks after immunization, elicited objective anti-prostate tumor responses. This forms the basis of the hypothesis underlying this proposal, namely that given the dynamic nature of the expression of PD-1 or LAG-3 following anti-tumor immunization, blockade of the transient upregulation of regulatory T cell markers (including PD-1 and/or LAG-3) using either antibody blockade or using TLR agonists that reduce expression of these regulatory receptors at the time of T-cell activation via anti-tumor immunization will lead to greater effector CD8 T cells and greater anti-tumor efficacy.

PROJECT SUMMARY ? PROJECT 4: Prostate cancer is a significant health problem worldwide for which new treatments are needed. Radiation therapy is a standard therapy for localized prostate cancer, delivered as either external beam radiation therapy or brachytherapy. Targeted radionuclide therapy (TRT) agents have been approved for advanced, metastatic prostate cancer, and others are in clinical testing. To date, the majority of studies using these agents have focused on identifying maximum doses that can eliminate tumor cells while having minimal effects on normal cells. The concept of using these types of agents to prime the tumor microenvironment for immunotherapy has been relatively unexplored. The overarching goal of this P01 is to evaluate TRT as a means to modulate the tumor microenvironment to enable immunotherapy treatments. Project 2 will evaluate TRT in combination with T-cell checkpoint inhibitor treatments, treatments which alone have been less successful in the treatment of prostate cancer. Project 3 will evaluate TRT in combination with intratumoral delivery of immune therapies for immunologically ?cold? tumors, an approach not feasible for most prostate cancers given the patterns of metastatic spread. While prostate cancer is generally considered to be an immunologically cold tumor, devoid of large numbers of tumor-infiltrating T cells, it nonetheless remains the only human cancer type to date for which an anti-tumor vaccine has been FDA-approved, likely on the basis of its ability to elicit tumor-specific T cells. This current Project will focus on prostate cancer and evaluate TRT in combination with antigen-specific anti-tumor vaccination. The hypothesis to be tested, based on existing preliminary data, is that TRT can modulate the tumor microenvironment by depleting immunosuppressive cell populations and promote infiltration of activated CD8+ T cells, and this may be modulated by the use of different TRT vectors, vaccination, and androgen deprivation therapy. This approach is complementary to the other Projects and Project 4 will inform the other Projects by permitting the direct evaluation of effects of TRT on the number and function of tumor antigen-specific CD8+ T cells, a level of analysis not possible in other Projects in which the targeted tumor antigens are not known. The work proposed will rely heavily on the RPR Core 1 for TRT vector production, AID Core 2 for dosimetry studies, and BB Core 3 for statistical and bioinformatics support. The underlying hypothesis will be tested with the following Aims: 1) to determine the effects of different TRT agents on the composition and effector function of immune infiltrating cells in murine prostate cancer models; 2) to determine whether antigen-specific tumor vaccination, when combined with different TRT agents, elicits greater numbers of tumor-specific infiltrating CD8+ T cells; and 3) to determine if CD8+ T cell infiltration and anti- tumor efficacy elicited with antigen-specific tumor vaccination and TRT treatment are augmented with androgen deprivation. It is expected these studies will inform the best design and sequence of rational, novel future clinical trials for patients with prostate cancer evaluating treatments using TRT in combination with anti-tumor vaccines.