MHC Class II–Transduced Tumor Cells Originating in the Immune-Privileged Eye Prime and Boost CD4 + T Lymphocytes that Cross-react with Primary and Metastatic Uveal Melanoma Cells Jacobus J. Bosch, 1,2 James A. Thompson, 1 Minu K. Srivastava, 1 Uzoma K. Iheagwara, 1 Timothy G. Murray, 3 Michal Lotem, 4 Bruce R. Ksander, 2 and Suzanne Ostrand-Rosenberg 1 1 Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland; 2 The Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts; 3 The Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida; and 4 Sharett Institute of Oncology, Hadassah University Hospital, Jerusalem, Israel Abstract Uveal melanoma, the most common malignancy of the eye, has a 50% rate of liver metastases among patients with large primary tumors. Several therapies prolong survival of metastatic patients; however, none are curative and no patients survive. Therefore, we are exploring immunotherapy as an alternative or adjunctive treatment. Uveal melanoma may be particularly appropriate for immunotherapy because primary tumors arise in an immune-privileged site and may express antigens to which the host is not tolerized. We are developing MHC class II (MHC II)–matched allogeneic, cell- based uveal melanoma vaccines that activate CD4 + T lymphocytes, which are key cells for optimizing CD8 + T-cell immunity, facilitating immune memory, and preventing tolerance. Our previous studies showed that tumor cells genetically modified to express costimulatory and MHC II molecules syngeneic to the recipient are potent inducers of antitumor immunity. Because the MHC II–matched allogeneic vaccines do not express the accessory molecule, Invariant chain, they present MHC II–restricted peptides derived from endogenously encoded tumor antigens. We now report that MHC II–matched allogeneic vaccines, prepared from primary uveal melanomas that arise in the immune-privileged eye, prime and boost IFN;-secreting CD4 + T cells from the peripheral blood of either healthy donors or uveal melanoma patients that cross-react with primary uveal melanomas from other patients and metastatic tumors. In contrast, vaccines prepared from metastatic cells in the liver are less effective at activating CD4 + T cells, suggesting that tumor cells originating in immune-privileged sites may have enhanced capacity for inducing antitumor immunity and for serving as immuno- therapeutic agents. [Cancer Res 2007;67(9):4499–506] Introduction Primary ocular or uveal melanoma is the most common malignancy of the eye and can be effectively treated with a variety of therapies, such as plaque radiotherapy, laser photocoagulation, transpupillary thermotherapy, trans-scleral resection, or enucle- ation of the tumor-bearing eye. Although these treatments limit the growth of the primary tumor and may partially preserve vision, they do not prevent the development of metastases, which occurs in f50% of patients with large tumors (1–3) and is universally fatal within f4 to 9 months of diagnosis (4). Although several treat- ments are available that increase median survival time to f15 months, metastatic uveal melanoma remains universally fatal (5, 6). We are exploring immunotherapy as an alternative or adjunctive treatment for metastatic uveal melanoma. Whereas most tumors arise from somatic cells and express an array of antigens to which the host is tolerant (7), uveal melanomas arise in the eye, an immune-privileged site, and may express molecules to which the host is not tolerized (8, 9). Consequently, cell-based tumor vaccines composed of primary uveal melanomas may be effective at inducing antitumor immunity in patients with metastatic disease, provided that the immunity is cross-reactive with metastatic uveal melanoma cells. Our efforts are focused on the activation of CD4 + T lymphocytes, which have long been recognized as critical for optimal CD8 + T-cell–mediated immunity (10–13), either through their classic role as ‘‘helper’’ T cells that provide cytokine support for CD8 + T cells (14, 15) or through their induction of CD40 expression on dendritic cells (‘‘licensing’’), which in turn activate CD8 + T cells (16–18). CD4 + T cells are also essential for generating CD8 + T memory cells and for preventing CD8 + T cells from being tolerized (19–22). In addition, IFNg production by CD4 + T cells facilitates tumor rejection by up-regulating tumor-expressed MHC molecules that improves CTL recognition, blocking neovasculari- zation, and directly inhibiting tumor cell proliferation (23, 24). Tofacilitatetheactivationoftumor-specificCD4 + Tcells,wehave made cell-based vaccines consisting of tumor cells that constitu- tively express MHC class I (MHC I) molecules, do not constitutively express MHC class II (MHC II) molecules, and are genetically modified to express CD80 costimulatory molecules and MHC II alleles that are syngeneic to the recipient. Because the MHC II– matched allogeneic ‘‘MHC II vaccine’’ cells do not constitutively express the MHC II accessory molecule, Invariant chain (Ii), they preferentially present endogenously synthesized tumor peptides rather than exogenously derived peptides (25). Expression of both CD80andMHCIIallowsthevaccinetodirectlypresentantigensthat prime MHC II–matched naive T cells (26–28). Recent studies indicate that tumor cell vaccines also activate CD4 + Tcells through the process of cross-dressing, in which the MHC II-peptide com- plexesaretransferredfromthevaccinecellsontothesurfaceofhost dendritic cells (29). Therefore, tumor cell vaccines possess both a direct and indirect route of activating tumor-specific CD4 + Tcells. The MHC II vaccines have several advantages that favor the activation of tumor-specific CD4 + T cells. ( a ) MHC II + Ii À cells Requests for reprints: Suzanne Ostrand-Rosenberg, Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250. Phone: 410-455-2237; Fax: 410-455-3875; E-mail: srosenbe@umbc.edu. I2007 American Association for Cancer Research. doi:10.1158/0008-5472.CAN-06-3770 www.aacrjournals.org 4499 Cancer Res 2007; 67: (9). May 1, 2007 Research Article Cancer Research. on September 26, 2015. © 2007 American Association for cancerres.aacrjournals.org Downloaded from