Hideo Okada, M.D., Ph.D.
Associate Professor of Neurological Surgery
and Surgery University of Pittsburgh
Co-Leader, Brain Tumor Program

Contact information:

University of Pittsburgh Cancer Institute
G12.a Research Pavilion at the Hillman Cancer Center
5117 Centre Ave. Pittsburgh, PA, 15213-1863
Phone: (412) 623-1111
FAX: (412) 623-4747
E-mail: okadah@.upmc.edu
http://www.upci.upmc.edu/research/clinical/brain/leader.html

Research Interests:

My ongoing and planned research projects seek to identify T-cell epitopes in glioma-associated antigens (GAAs) and develop immunotherapy strategies that promote efficient central nervous system (CNS) tumor homing and function of anti-tumor T-cells. In parallel with this bench research, I am designing and conducting early phase clinical trials that translate our laboratory discoveries directly to patients. In the summaries below of ongoing and planned projects, bracketed information includes funding sources, project leaders, and funding status.

Identification and Characterization of Human Glioma Cytotoxic T Cell Epitopes Targeting Antigens Expressed in Glioma Stem Cells [Supported by James S. McDonnell Foundation]

Our previous studies demonstrated the efficacy of peripheral vaccination with interleukin (IL)-4 gene transduced whole glioma cells in rats bearing intracranial syngeneic gliomas (Okada et al., 1999; Okada et al., 1998; Okada et al., 2001b). We have conducted corollary phase I clinical trials (Okada et al., 2000b; Okada et al., 2001a; Okada et al., 2003) , and our preliminary data from two patients treated with IL-4 gene-transfected glioma vaccines demonstrated clinical and radiographic responses (Okada et al., 2003) . Although this “whole-cell” glioma vaccine seems promising, for better efficacy and safety, we have been directing our focus on identifying glioma-specific T-cell immuno epitopes, which will allow us to design peptide-based glioma specific vaccines. Using bioinformatics and synthetic peptides designed in candidate antigens, we recently identified a human leukocyte antigen (HLA) -A2 restricted cytotoxic T cell (CTL) epitope in GAAs, interleukin-13 receptor a 2 chain (IL-13R a 2) (Eguchi et al., 2006; Okano et al., 2002) ] and a novel tyrosine kinase receptor, EphA2 (Hatano et al., 2005) , both of which are strongly expressed in gliomas but not in normal brains. We believe identification of multiple CTL epitopes is important to develop truly effective vaccines due to the marked heterogeneity of human malignant gliomas. In addition, we are currently trying to expand the repertoire of GAA epitope peptides in other HLA-types to maximize the utility of CTL epitopes in larger patient populations. A s HLA-A2 is the most common haplotype found in approximately 45% of US population, we have chosen HLA-A2-restricted epitopes as prototypes for the proof of principle.

The cancer stem cell hypothesis suggests that neoplastic clones are maintained exclusively by a rare fraction of cells with stem cell properties. Recently, it has been reported that a CD133 + cell subpopulation from human brain tumors exhibited stem cell properties both in vitro and in vivo (Singh et al., 2004; Yuan et al., 2004) . We are currently characterizing the unique antigenic profiles of CD133 + human glioma stem cells. We plan to identify novel CTL-epitope peptides within CD133 + glioma-initiating cells, thereby developing novel immunotherapy strategies targeting glioma-initiating stem cells, which are responsible for glioma-growth.

Cytokine Gene Therapy for Brain Tumors [ P01CA100327: Storkus (PI); Okada, Project 1 leader (active)]

Our previous study demonstrated that the efficacy of vaccinations using IL-4 transduced tumor cells is mediated by the induction of anti-tumor Type-1 T-cell response (Eguchi et al., 2005) (i.e. interferon [IFN]- g dominant cellular response). In addition, our recent studies showed that injection of intracranial tumors with dendritic cells secreting interferon- a ( DC-IFN a ) yields clinical benefit, with DC-IFN a migrating to the draining lymph nodes (i.e. cervical lymph nodes), where they are capable of cross-priming tumor antigen-specific T cells (Okada et al., 2004) .

To develop the most effective therapeutic approaches incorporating this strategy, we must better understand the impact of cytokine-gene transfected dendritic cells on the immunobiology of the CNS tumor-microenvironment. We hypothesize that the CNS tumor microenvironment inhibits the survival and function of both resident and injected dendritic cells through various molecular mechanisms, including, but not limited to, FasL-Fas and TGF- b pathways. Cytokine gene therapy may overcome these inhibitory effects and augment the ability of resident (via effects in trans ) and injected dendritic cells to mediate DC1-type functions required to promote and/or sustain Type-1 anti-tumor T cell responses in the brain. In particular, extended secretion of Type-1 cytokines that act on antigen-experienced memory T cells (such as IL-23) would be predicted to directly or indirectly (via IFN- g and CXCR3 ligands) promote the recruitment and potentiation of adoptively transferred or in situ primed tumor antigen-specific T cells, yielding consequent therapeutic benefit to intracranial tumor-bearing mice . In this project, we will determine effective single or combined cytokine gene therapy approaches that optimize Type-1 effector T cell recruitment and function into/within the tumor microenvironment, which we hypothesize will be linked to tumor regression. This work will in turn inform the design of novel clinical trials.

Glioma Vaccines in Combination with Poly-ICLC [ R01NS055140: Okada (PI) (pending)]

Available evidence clearly shows that single modality cancer therapies remain suboptimal and that combination regimens targeting the immune system at multiple coordinated levels must be developed if significant clinical benefit is to be achieved. We believe that the systemic induction of anti-tumor immune responses by peripheral vaccines should be combined with modalities that enhance the homing and the function of vaccine-induced effector cells within CNS tumor sites. Toward this end, we believe that polyinosinic-polycytidylic acid (poly-IC) stabilized with poly-lysine and carboxymethylcellulose (poly-ICLC) is an attractive agent capable of inducing such inflammatory cytokines as IFN- a (Wang et al., 2004b; Farina et al., 2005; Park et al., 2006) . Our preliminary data with mouse models indicate that poly-ICLC promotes not only the proliferation of GAA-specific CTLs but also the homing receptor/integrin molecule expression by T cells that is critical for their tropism and infiltration into CNS tumors, such as expression of very late antigen-4 (Calzascia et al., 2005) . In addition, poly-ICLC administration enhanced the CNS tumor-homing of GAA-specific CTLs. We hypothesize that addition of poly-ICLC will enhance the effect of dendritic cell-based peripheral vaccination with GAA-derived CTL-epitopes by augmenting the induction, persistence, and CNS tumor homing of anti-GAA CTLs through the IFN- a / b signaling.

Our preliminary data also indicate that poly-ICLC treatment, especially in combination with GAA-vaccines, induces immunoregulatory mechanisms in the CNS tumor environment, such as indoleamine 2,3 dioxygenase expression. High numbers of regulatory T cells persist in the CNS tumors following poly-ICLC treatment. We will therefore determine whether specific blockade of these factors within the CNS tumor environment improves the efficacy of the combination approach by counteracting immunological homeostatic mechanisms. Even though we believe our GAA-targeted strategies will not promote CNS autoimmune responses, we will carefully examine the potential for autoimmune encephalitis before designing prospective clinical trials.

To summarize, we believe poly-ICLC, which has been previously clinically evaluated (Salazar et al., 1996) , can be effectively and safely combined with GAA-specific vaccine strategies to achieve superior therapeutic efficacy. Indeed, we recently began a phase I/II trial of vaccination with human GAA peptides identified in our laboratory in conjunction with poly-ICLC in participants with recurrent malignant glioma. While safety will be the primary endpoint, we will also examine whether this form of vaccine can induce Type-1 GAA-specific CD8 + T-cells, and mediate anti-tumor effects.

Development of Molecularly Targeted Multidisciplinary Vaccine Approaches [ P01NS40923: Pollack (PI); Okada, Project 2 leader (active)]

In collaboration with other investigators in our Brain Tumor Program, we are evaluating the roles of signal transducers and activators of transcription (STAT)3 and its inhibitors in glioma cell growth and anti-glioma immunity. Tumor-derived biomodulators, such as IL-6 and IL-10, activate STAT3 (Lang, 2005; Gamero et al., 2004) , thereby mediating tumor immune escape (Kortylewski et al., 2005; Wang et al., 2004a; Gamero et al., 2004) . This is a relevant concern, given the ability of poly-ICLC to induce production of IL-6 and IL-10 in microglia and astrocytes (Jack et al., 2005; Bsibsi et al., 2006) . Accordingly, we are evaluating whether inhibition of STAT3 signals may improve the efficacy of poly-ICLC assisted GAA-based vaccines.

In parallel, we have found that indoleamine 2,3 dioxygenase (IDO) inhibits not only immune cells but also the proliferation of herpes simplex viruses. We are therefore collaborating with Dr. Joseph Glorioso and his group in University of Pittsburgh to determine whether poly-ICLC-assisted GAA vaccines can be efficiently combined with herpes simplex therapy under the inhibition of IDO.

We believe that proper molecular targets—such as TLR3, STAT3 and IDO signals—can be effectively and safely combined with GAA-specific vaccine strategies to achieve superior therapeutic efficacy. The results from these studies will directly shape the design of combination therapy regimens to be evaluated in future phase I/II clinical trials.

Phase I/II Trial of GAA peptide loaded " a -Type-1-Polarized Dendritic Cells" ( a DC1) Vaccines in Patients with Recurrent Malignant Glioma [R21CA117152: Okada (PI) active]

Our data from the IL-4 vaccine trial suggest that immunologic events may be linked with encouraging clinical responses in patients with gliomas (Okada et al., 2003; Okada et al., 2001a; Okada et al., 2000a; Okada et al., 2000b) ], providing a strong rationale for further development of vaccine-based therapies. However, the time delay required for generation of an autologous whole glioma cell vaccine in conjunction with expanding transduced cells is a limiting factor of this approach in a neoplasm prone to rapid progression. In addition, whole cell glioma-based vaccines raise a theoretical concern for inducing autoimmune encephalitis against a broad array of self antigens.

We have launched a novel vaccine trial based directly on our original characterization of GAA-derived CTL epitopes (UPCI 04-136) (Eguchi et al., 2006; Okano et al., 2002; Hatano et al., 2005) ]. This study reflects institutional translational collaboration that will continue to play an important role in my work. For the vaccine vehicle, we use a novel culture method to produce functionally polarized DCs that efficiently induce Type-1 CTL responses [i.e., a DC1 ] , invented by Dr. Pawel Kalinski and his colleague (Mailliard et al., 2004) .

HLA-A2+ patients with recurrent malignant glioma receive at least 4 ultrasound-guided vaccinations into lymph nodes of a DC1s loaded with GAA epitopes (IL-13R a 2 345-353:1A9V , EphA2 881-889, gp100 209-217 and YKL-40 201-210 ) at 2-week intervals using a dose-escalation scheme. We will enroll a total of 20-29 patients to evaluate vaccine safety as the primary objective and induction of immune response against GAA peptides and clinical responsiveness as secondary objectives.

To the best of our knowledge, we are conducting one of the first molecularly targeted vaccine trials for malignant gliomas. We propose the following specific hypotheses: 1) This form of vaccination will be safe . Endpoints will therefore be to determine the maximal tolerated dose of a DC1 vaccines (based on injected dendritic cell numbers), using standard criteria for dose limiting toxicity. 2) This form of vaccination will induce increases in measurable specific T cell responses directed against the targeted GAAs . We will assess the response against GAA-epitopes using IFN- g enzyme-linked immuno-spot (ELISPOT) as the primary immunological endpoint. Monitoring T cell frequencies using MHC-peptide tetramer assays will serve as secondary assessment tools. In addition, we will assess the preliminary anti-tumor clinical activity of these vaccines based on differences in radiological response (MRI), 4- and 6- month progression free survival, and overall survival.

Information from this phase I/II study will inform the design of subsequent trials in patient populations among whom an even greater degree of clinical benefit might be realized: for example, prophylactic vaccines for low-grade gliomas that may recur as more malignant tumors following initial resection and adjuvant vaccines for patients with newly diagnosed malignant gliomas.

 

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