NY-ESO-1 is a “cancer-testis” antigen expressed in many cancers. ISCOMATRIX is a saponin-based adjuvant that induces antibody and T cell responses. We performed a placebo-controlled clinical trial evaluating the safety and immunogenicity of recombinant NY-ESO-1 protein with ISCOMATRIX adjuvant. Forty-six evaluable patients with resected NY-ESO-1-positive tumors received three doses of vaccine intramuscularly at monthly intervals. The vaccine was well tolerated. We observed high-titer antibody responses, strong delayed-type hypersensitivity reactions, and circulating CD8+ and CD4+ T cells specific for a broad range of NY-ESO-1 epitopes, including known and previously unknown epitopes. In an unplanned analysis, vaccinated patients appeared to have superior clinical outcomes to those treated with placebo or protein alone. The vaccine is safe and highly potent immunologically.

Dendritic cells (DCs) are being evaluated for cancer immunotherapy due to their unique ability to induce tumor-directed T-cell responses. Here we report that the type of human DC, the mode of activation, and the strategy for delivery of antigen are 3 critical factors for efficient stimulation of tumor-specific CD8 ؉ and CD4 ؉ T cells. Only CD1c ؉ blood DCs and monocyte-derived DCs (MoDCs) were capable of presenting epitopes of the full-length tumor antigen NY-ESO-1 on both major histocompatibility complex (MHC) class I (cross-presentation) and MHC II, whereas plasmacytoid DCs were limited to MHC II presentation. Cross-presentation was inefficient for soluble protein, but highly efficient for antigen-antibody immune complexes (NY-ESO-1/IC) and for protein formulated with ISCOMATRIX adjuvant (NY-ESO-1/IMX). DC activation with CD40L further enhanced cross-presentation efficiency. The mode of antigen delivery was found to be a determining factor for cytosolic proteolysis by DCs. Immune complexes (ICs) targeted a slow, proteasomedependent cross-presentation pathway, whereas ISCOMATRIX (IMX) targeted a fast, proteasome-independent pathway. Both cross-presentation pathways resulted in a long-lived, T-cell stimulatory capacity, which was maintained for several days longer than for DCs pulsed with peptide. This may provide DCs with ample opportunities for sensitizing tumorspecific T cells against a broad array of tumor antigen epitopes in lymph nodes. IntroductionTo achieve tumor cell killing by cytotoxic CD8 ϩ T cells (CTLs), cancer vaccines target major histocompatibility complex (MHC) class Irestricted epitopes. CTL responses alone may not be sufficient for effective anticancer immunity, and additional help from CD4 ϩ T cells is required for optimal CTL priming and memory induction. [1][2][3][4] A variety of vaccine strategies are being developed to generate an integrated CD4 ϩ and CD8 ϩ T-cell response. One strategy uses dendritic cells (DCs), which have the unique capacity to not only present exogenous antigen on MHC II, but also to "cross-present" these on MHC I. 5 DC-based clinical trials have demonstrated "proof of concept" using primary DCs isolated directly from peripheral blood or DCs generated in vitro from monocytes (MoDCs) or CD34 ϩ progenitors, pulsed with MHC Irestricted peptides (reviewed in Davis et al 6 ). We and others have previously studied the functional profiles of different DC populations providing valuable insights into their potential clinical utility. [7][8][9] Despite this, the rational design of DC-based cancer vaccines still lacks some critical information. What are the optimal approaches to achieve antigen presentation on both MHC I and MHC II? Which DC population is best suited for this purpose? How should these DCs be matured or activated?We have used the tumor antigen NY-ESO-1 as a model antigen to address these questions. NY-ESO-1 is a 180 amino acid protein, which is absent in normal tissues apart from testis, but is expressed in a variety of common human cancers including melanoma, ...