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Tumor antigen–specific CD4+ T cells that directly recognize cancer cells are important for orchestrating antitumor immune responses at the local tumor sites. However, the mechanisms of direct MHC class II (MHC-II) presentation of intracellular tumor antigen by cancer cells are poorly understood. We found that two functionally distinct subsets of CD4+ T cells were expanded after HLA-DPB1*04 (DP04)-binding NY-ESO-1157-170 peptide vaccination in patients with ovarian cancer. Although both subsets recognized exogenous NY-ESO-1 protein pulsed on DP04+ target cells, only one type recognized target cells with intracellular expression of NY-ESO-1. The tumor-recognizing CD4+ T cells more efficiently recognized the short 8–9-mer peptides than the non–tumor-recognizing CD4+ T cells. In addition to endosomal/lysosomal proteases that are typically involved in MHC-II antigen presentation, several pathways in the MHC class I presentation pathways, such as the proteasomal degradation and transporter-associated with antigen-processing–mediated peptide transport, were also involved in the presentation of intracellular NY-ESO-1 on MHC-II. The presentation was inhibited significantly by primaquine, a small molecule that inhibits endosomal recycling, consistent with findings that pharmacologic inhibition of new protein synthesis enhances antigen presentation. Together, our data demonstrate that cancer cells selectively present peptides from intracellular tumor antigens on MHC-II by multiple nonclassical antigen-processing pathways. Harnessing the direct tumor-recognizing ability of CD4+ T cells could be a promising strategy to enhance antitumor immune responses in the immunosuppressive tumor microenvironment. Cancer Immunol Res; 2(4); 341–50. ©2013 AACR.

PDF file - 152K, MHC class II antigen presentation pathway of intracellular NY-ESO-1 by SK-MEL-37.

PDF file - 97K, Effect of IFN-gamma treatment of HLA-DP4+ melanoma cell lines on intracellular NY-ESO-1 to TR-CD4.

PDF file - 110K, Cell surface molecules expressed on SK-MEL-37.

PDF file, 64K, In-vitro immunostimulatory activity of MBV on PBMC.

PDF file 90K, Supplementary Figure Legends

Conflict of Interest from NY-ESO-1 DNA Vaccine Induces T-Cell Responses That Are Suppressed by Regulatory T Cells

PDF file - 1810K, Detection of NY-ESO-1-specific CD4+ T cells by intracellular cytokine staining. CD4+ T cells were stimulated once with T-cell depleted PBMC pulsed with NY-ESO-1 assay OLP and after 22-23 day culture, NY-ESO-1-specific IFN-γ and IL-5 production was evaluated by intracellular cytokine staining. Peptide-pulsed or unpulsed autologous EBV-B cells pulsed or unpulsed with 20-mer NY-ESO-1 peptides covering areas indicated were used as target cells. Responses shown at week 16 after vaccination in two patients (M09 and M19) representative of Cohort 2 and 3, respectively.

Purpose: Vaccination with full-length human tumor antigens aims at inducing or increasing antitumor immune responses, including CD8 CTL in cancer patients across the HLA barrier. We have recently reported that vaccination with a recombinant tumor-specific NY-ESO-1 (ESO) protein, administered with Montanide and CpG resulted in the induction of specific integrated antibody and CD4 T cell responses in all vaccinated patients examined, and significant CTL responses in half of them. Vaccine-induced CTL mostly recognized a single immunodominant region (ESO 81-110). The purpose of the present study was to identify genetic factor(s) distinguishing CTL responders from nonresponders.Experimental Design: We determined the HLA class I alleles expressed by CTL responders and nonresponders using high-resolution molecular typing. Using short overlapping peptides spanning the ESO immunodominant CTL region and HLA class I/ESO peptide tetramers, we determined the epitopes recognized by the majority of vaccine-induced CTL.Results: CTL induced by vaccination with ESO protein mostly recognized distinct but closely overlapping epitopes restricted by a few frequently expressed HLA-B35 and HLA-Cw3 alleles. All CTL responders expressed at least one of the identified alleles, whereas none of the nonresponders expressed them.Conclusions: Expression of HLA-B35 and HLA-Cw3 is associated with the induction of immunodominant CTL responses following vaccination with recombinant ESO protein. Because recombinant tumor-specific proteins are presently among the most promising candidate anticancer vaccines, our findings indicate that the monitoring of cancer vaccine trials should systematically include the assessment of HLA association with responsiveness.

Supplementary Table 2 from Cancer-Testis Antigens: Expression and Correlation with Survival in Human Urothelial Carcinoma

PDF file, 39K, Reactivation of cytokine response by further MBV administration after a MBV treatment-free period.

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Supplementary Figure S1 from HLA Class I–Associated Immunodominance Affects CTL Responsiveness to an ESO Recombinant Protein Tumor Antigen Vaccine

PDF file 79K, GAG-HERV-K ch22q11.23 features. Endogenous retrovirus K from chromosome 22 is located on the q11.23 region, nearby the BCR, ZDHHC8P, IGLL1 and RGL4 genes. HERV-K ch22q11.23 has GAG-PRO, POL and ENV genes flanked by LTR sequences. The GAG gene has an ORF encoding a 715aa protein that contains P10, P24 and Zinc finger domains. {delta}: deletions; I: early stop codons; --> primer binding regions; ABS: antibody binding site for monoclonal antibody TI-35 (see Supplementary Fig. S3C)

Supplementary Table 1 from Cancer-Testis Antigens: Expression and Correlation with Survival in Human Urothelial Carcinoma

PDF file, 82K, Trial design schema.

PDF file - 2015K, Injection site reaction in patient M21

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Supplementary Table 3 from Cancer-Testis Antigens: Expression and Correlation with Survival in Human Urothelial Carcinoma

Gene specific PCR primers

Supplementary Figures S1-S3 from MAGE-A Inhibits Apoptosis in Proliferating Myeloma Cells through Repression of Bax and Maintenance of Survivin

Purpose: Different vaccination strategies against the NY-ESO-1 antigen have been employed in an attempt to induce antitumor immune responses. Antigen-specific effector T-cell responses have been reported in a subset of vaccinated patients; however, these responses have not consistently correlated with disease regression. Here, we report for the first time clinical and immune responses generated by the NY-ESO-1 DNA vaccine administered by particle-mediated epidermal delivery to cancer patients.Experimental Design: Eligible patients received treatment with the NY-ESO-1 DNA vaccine. Clinical outcomes and immune responses were assessed.Results: The NY-ESO-1 DNA vaccine was safely administered and induced both antigen-specific effector CD4 and/or CD8 T-cell responses in 93% (14 of 15) of patients who did not have detectable pre-vaccine immune responses. Despite the induction of antigen-specific T-cell responses, clinical outcomes consisted predominantly of progressive disease. Detectable effector T-cell responses were inconsistent and did not persist in all patients after completion of the scheduled vaccinations. However, high-avidity CD4 T-cell responses that were either undetectable pre-vaccine or found to be diminished at a later time during the clinical trial were detected in certain patients' samples after in vitro depletion of regulatory T cells.Conclusions: Regulatory T cells play a role in diminishing vaccine-induced antigen-specific effector T-cell responses in cancer patients. The NY-ESO-1 DNA vaccine represents a feasible immunotherapeutic strategy to induce antigen-specific T-cell responses. Counteracting regulatory T-cell activity before vaccination may lead to prolonged effector T-cell responses and possibly antitumor responses in cancer patients.

Supplementary Data from Two Distinct Mechanisms of Augmented Antitumor Activity by Modulation of Immunostimulatory/Inhibitory Signals

PDF file - 70K, Incidence of treatment-related adverse events by maximum grade

PDF file 204K, Alignment of GAG proteins derived from human endogenous retroviruses and respective epitopes recognized by prostate cancer patient sera. A, Detail alignment from several GAG-HERV-K family members and the TI-35 binding site (red) highlighting the amino-acid differences present in GAG-HERV-K ch22q11.23 (blue). B, Western-blot analysis of immunoprecipitation of GAG-HERV-K from VCaP and LNCaP prostate cancer cell lines. WFP prostate cancer patient serum (WFP) was incubated with VCaP or LNCaP protein extract for 2 hours at 4{degrees}C. Protein-antibody complexes were pulled down using anti-human IgG sepharose beads. The pull-down pellet was submitted to SDS-PAGE and Western-blot analysis. Reactivity to GAG-HERV-K protein was developed by incubating the membrane with TI-35 monoclonal antibody. A pool of healthy donor sera was used as control (Con). C, Summary of ELISA results from epitope mapping using 20mers peptides overlapping by 10aa (71 peptides tested in total from JPT Innovative Peptide Solution, Berlin, Germany) spanning GAG-HERV-K and tested individually for recognition by monoclonal antibody TI-35 and different prostate cancer patient sera seropositive for GAG-HERV-K protein. The square symbol represents a positive reaction to the corresponding peptide (labeled by aminoacid start and end position). A pool of healthy donor sera was used as control (Con pool). Plates were coated with 5 uM peptide and the reaction was performed as previously described in methods

Purpose: Blockade of CTL-associated antigen-4 (CTLA-4), an inhibitory immunomodulatory molecule on T cells, has been shown to enhance T-cell responses and induce tumor rejection, and a number of clinical trials with anti-CTLA-4 blocking monoclonal antibody (mAb) are under way. However, accumulating evidence indicates that anti-CTLA-4 mAb increases the number of CD4+CD25+Foxp3+ regulatory T cells (Treg) and that anti-CTLA4 mAb alone is often insufficient to reject established tumors in mice and humans. Thus, finding maneuvers to control Tregs and other immunosuppressive mechanisms remains a critical challenge.Experimental Design: The potential to enhance antitumor immune responses by combining anti-CTLA-4 mAb with anti–glucocorticoid-induced tumor necrosis factor receptor family related gene (GITR) mAb, a costimulatory molecule that abrogates directly/indirectly Treg-mediated immune suppression or anti-CD25 mAb that depletes Tregs was analyzed with two tumor models, CT26 (a murine colon carcinoma cell line) and CMS5a (a murine fibrosarcoma cell line).Results: Anti-CTLA-4/anti-GITR mAb combination treatment exhibited far stronger antitumor effects compared with either antibody alone. This strong antitumor effect was attributed to (a) increased numbers of CD8+ T cells infiltrating tumor sites in anti-CTLA-4 mAb–treated mice and (b) increased cytokine secretion and Treg resistance of tumor-specific CD8+ T cells with strongly upregulated CD25 expression in anti-GITR mAb–treated mice, indicating distinct quantitative/qualitative changes induced by modulating CTLA-4 and GITR signaling.Conclusions: This study shows that combined treatment with different immune modulators can augment antitumor immune responses and provides justification for exploring anti-CTLA-4/anti-GITR mAb combination treatment in the clinic. Clin Cancer Res; 16(10); 2781–91. ©2010 AACR.

Purpose: Cancer-testis genes mapping to the X chromosome have common expression patterns and show similar responses to modulators of epigenetic mechanisms. We asked whether cancer-testis gene expression occurred coordinately, and whether it correlated with variables of disease and clinical outcome of non–small cell lung cancer (NSCLC).Experimental Design: Tumors from 523 NSCLC patients undergoing surgery were evaluated for the expression of nine cancer-testis genes (NY-ESO-1, LAGE-1, MAGE-A1, MAGE-A3, MAGE-A4, MAGE-A10, CT7/MAGE-C1, SSX2, and SSX4) by semiquantitative PCR. Clinical data available for 447 patients were used to correlate cancer-testis expression to variables of disease and clinical outcome.Results: At least one cancer-testis gene was expressed by 90% of squamous carcinoma, 62% of bronchioloalveolar cancer, and 67% of adenocarcinoma samples. Statistically significant coexpression was observed for 34 of the 36 possible cancer-testis combinations. Cancer-testis gene expression, either cumulatively or individually, showed significant associations with male sex, smoking history, advanced tumor, nodal and pathologic stages, pleural invasion, and the absence of ground glass opacity. Cox regression analysis revealed the expression of NY-ESO-1 and MAGE-A3 as markers of poor prognosis, independent of confounding variables for adenocarcinoma of the lung.Conclusions: Cancer-testis genes are coordinately expressed in NSCLC, and their expression is associated with advanced disease and poor outcome.

Purpose: Long peptides are efficiently presented to both CD4+ and CD8+ T cells after intracellular processing by antigen-presenting cells. To investigate the safety and in vivo immunogenicity of synthetic overlapping long peptides (OLP) from a human tumor self-antigen, we conducted a phase I clinical trial with OLP from cancer-testis antigen NY-ESO-1 in various adjuvant combinations.Experimental Design: Twenty-eight patients with advanced ovarian cancer in second or third remission were enrolled sequentially in three cohorts and received at least one vaccination. Patients in Cohort 1 (n = 4) received 1.0 mg OLP, Cohort 2 (n = 13) received OLP in Montanide-ISA-51, and Cohort 3 (n = 11) received OLP + 1.4 mg Poly-ICLC in Montanide-ISA-51 on weeks 1, 4, 7, 10, and 13. Humoral and cellular responses were evaluated by standardized immunomonitoring techniques (ELISA, ELISPOT assay, intracellular cytokine staining, and tetramer staining).Results: The vaccine was generally well tolerated with injection site reactions and fatigue that resolved. NY-ESO-1–specific antibody and CD8+ T cells were undetectable after vaccination with OLP alone, but were found in 6 of 13 (46%) and 8 of 13 (62%) patients, respectively, after vaccination with OLP+Montanide, and in 10 of 11 (91%) and 10 of 11 (91%) patients, respectively, after vaccination with OLP+Montanide+Poly-ICLC. NY-ESO-1–specific CD4+ T cells were detected in all patients with greater frequency and polyclonality when Montanide-ISA-51 was used for vaccination. Inclusion of Poly-ICLC as an adjuvant further accelerated the induction of NY-ESO-1–specific immune responses.Conclusions: The current study shows that NY-ESO-1 OLP vaccine is safe and rapidly induces consistent integrated immune responses (antibody, CD8+ and CD4+) in nearly all vaccinated patients when given with appropriate adjuvants. Clin Cancer Res; 18(23); 6497–508. ©2012 AACR.

PDF file - 196K, Humoral immune responses to NY-ESO-1 protein and peptides in individual patients throughout vaccination with NY-ESO-1 OLP. A) Reciprocal titers of plasma IgG antibodies were measured throughout vaccination by ELISA against NY-ESO-1 recombinant protein. Each patient was tested for all available time points, from prestudy (pre) up to week (w) 16. B) IgG plasma antibody responses were analyzed using 20-mer OLP in ELISA from samples at the time points where maximal titers had been achieved against NY-ESO-1 protein following vaccination. Peaks represent titers against 20-mer individual peptides centered around amino-acids from NY-ESO-1 shown along the X-axis. Reciprocal titers were considered significant if > 100. Assays representative of at least 2 repeats.

Purpose: The type I Melanoma Antigen GEnes (MAGEs) are commonly expressed in cancers, fueling speculation that they may be therapeutic targets with oncogenic potential. They form complexes with RING domain proteins that have E3 ubiquitin ligase activity and promote p53 degradation. MAGE-A3 was detected in tumor specimens from patients with multiple myeloma and its expression correlated with higher frequencies of Ki-67+ malignant cells. In this report, we examine the mechanistic role of MAGE-A in promoting survival of proliferating multiple myeloma cells.Experimental Design: The impact of MAGE-A3 expression on survival and proliferation in vivo was examined by immunohistochemical analysis in an independent set of tumor specimens segregated into two groups: newly diagnosed, untreated patients and patients who had relapsed after chemotherapy. The mechanisms of MAGE-A3 activity were investigated in vitro by silencing its expression by short hairpin RNA interference in myeloma cell lines and primary cells and assessing the resultant effects on proliferation and apoptosis.Results: MAGE-A3 was detected in a significantly higher percentage of relapsed patients compared with newly diagnosed, establishing a novel correlation with progression of disease. Silencing of MAGE-A showed that it was dispensable for cell cycling, but was required for survival of proliferating myeloma cells. Loss of MAGE-A led to apoptosis mediated by p53-dependent activation of proapoptotic Bax expression and by reduction of survivin expression through both p53-dependent and -independent mechanisms.Conclusions: These data support a role for MAGE-A in the pathogenesis and progression of multiple myeloma by inhibiting apoptosis in proliferating myeloma cells through two novel mechanisms. Clin Cancer Res; 17(13); 4309–19. ©2011 AACR.

Supplementary Figure S1; Supplementary Table S1.

Purpose: Mixed bacterial vaccine (MBV, Coley's toxins) is a historical, vaguely defined preparation of heat-inactivated Streptococcus pyogenes and Serratia marcescens used as nonspecific immunotherapy in the treatment of cancer. The mechanism of action is suspected to have an immunologic basis, yet it is poorly defined up to now. We developed a new, biochemically well defined and current good manufacturing practice–compliant MBV preparation, which has been investigated in patients with NY-ESO-1 expressing cancers.Experimental Design: Patients received MBV subcutaneously at a starting dose of 250 EU (endotoxin units) twice a week. The MBV dose was escalated in each patient until a body temperature of 38°C to 39.5°C was induced or up to the maximum dose of 547.000 EU. Changes in serum cytokine levels were determined and immune responses to NY-ESO-1 were evaluated. Tumor response was assessed according to RECIST.Results: Twelve patients were enrolled and 11 of them developed fever after the administration of MBV. Ten of 12 patients showed a consistent increase in serum IL-6 levels with the highest levels coinciding with the highest body temperature. A subgroup of patients showed increasing levels of TNF-α, IFN-γ, and IL1-β. A patient with metastatic bladder cancer showed a partial tumor response strongly correlated with MBV-induced fever and highly elevated levels of several cytokines.Conclusions: MBV at fever-inducing dose levels can lead to a massive induction of immunoregulatory cytokines that may be involved in inducing tumor regressions. We propose to further explore the role of MBV as a potent immune modulator at higher dose levels and in conjunction with antigen-specific cancer vaccines. Clin Cancer Res; 18(19); 5449–59. ©2012 AACR.

PDF file - 65K, Immunohistochemical analysis of NY-ESO-1 expression (mAb E978) in tumor tissue and vaccine regimen

CT-X expression frequency and clinical characteristics

Purpose: Human endogenous retroviruses (HERV) encode 8% of the human genome. While HERVs may play a role in autoimmune and neoplastic disease, no mechanistic association has yet been established. We studied the expression and immunogenicity of a HERV-K GAG protein encoded on chromosome 22q11.23 in relation to the clinical course of prostate cancer.Experimental Design:In vitro expression of GAG-HERV-K was analyzed in panels of normal and malignant tissues, microarrays, and cell lines, and effects of demethylation and androgen stimulation were evaluated. Patient sera were analyzed for seroreactivity to GAG-HERV-K and other self-antigens by ELISA and seromics (protein array profiling).Results: GAG-HERV-K expression was most frequent in prostate tissues and regulated both by demethylation of the promoter region and by androgen stimulation. Serum screening revealed that antibodies to GAG-HERV-K are found in a subset of patients with prostate cancer (33 of 483, 6.8%) but rarely in male healthy donors (1 of 55, 1.8%). Autoantibodies to GAG-HERV-K occurred more frequently in patients with advanced prostate cancer (29 of 191 in stage III–IV, 21.0%) than in early prostate cancer (4 of 292 in stages I–II, 1.4%). Presence of GAG-HERV-K serum antibody was correlated with worse survival of patients with prostate cancer, with a trend for faster biochemical recurrence in patients with antibodies to GAG-HERV-K.Conclusions: Preferential expression of GAG-HERV-K ch22q11.23 in prostate cancer tissue and increased frequency of autoantibodies observed in patients with advanced prostate cancer make this protein one of the first bona fide retroviral cancer antigens in humans, with potential as a biomarker for progression and biochemical recurrence rate of prostate cancer. Clin Cancer Res; 19(22); 6112–25. ©2013 AACR.

Purpose: Vaccination against human cancer is a promising therapeutic approach but the optimal antigen or antigens remain undefined. Cancer-testis antigens (CTA), a family of tumor-associated antigens, have both potent immunogenicity and restricted expression patterns in normal adult tissues, highly desirable characteristics for targets of anticancer vaccines. These antigens were evaluated for both the degree of expression and prognostic value in cancer of the urothelium.Experimental Design: The expression patterns of nine CTAs (NY-ESO-1, LAGE-1, MAGE-A1, MAGE-A3, MAGE-A4, MAGE-A10, CT7, CT10, and GAGE) were examined by immunohistochemistry and reverse transcription-PCR in a panel of high-grade urothelial carcinomas of the urinary bladder. Also assessed were correlations between the expression of CTAs by immunohistochemistry and both disease-free and overall survival.Results: At least one CTA was expressed in 77% of samples and 61% of these tumors expressed more than one CTA. Additionally, patients with CT10-positive tumors had an improved disease-free survival (P = 0.008) and overall survival (P = 0.037) compared with patients with CT10-negative tumors.Conclusions: These findings establish CTAs as potential prognostic markers and as target candidates for vaccine development for patients with urothelial carcinoma.

PDF file 63K, Correlation between antibodies against GAG-HERV-K and group risk or Gleason score in cancer patients. Prostate cancer patients were split (A) in 3 groups according to Gleason score and classified from group risk 1 to 3 and compared to healthy donors (HD), or (B) in 3 groups according to Gleason score as indicated. Antibodies anti-GAG-HERV-K were detected and analyzed as in Fig. 4. Asterisk denotes significantly higher frequency of seropositive patients (titer > 100) in risk group 3 and Gleason {greater than or equal to} 8 (Chi-square test, p

PDF file 341K, qPCR gene expression analysis of chromosome 22q11.23 region in cancer tissues. Total RNA from cancer tissues was submitted to DNAse treatment and reverse transcriptase reaction for cDNA synthesis. The resulting cDNA was used on qPCR to detect the expression of GAG-HERV-K and the neighbor genes BCR, IGGL1, RGL4 and ZDHHC8P. The results are expressed as relative expression to GAG-HERV-K levels in normal prostate. GAG-HERV-K expression is relative to GAPDH. BCR, IGGL1, RGL4 and ZDHHC8P expression is relative to TFRC

PDF file, 86K, In-vitro activity of MBV on DC.

Supplementary Data from NY-ESO-1 DNA Vaccine Induces T-Cell Responses That Are Suppressed by Regulatory T Cells

Purpose: NY-ESO-1, one of the most immunogenic tumor antigens, is expressed in 15% to 25% of metastatic prostate cancers. The immunological and clinical effects of vaccination with recombinant NY-ESO-1 protein combined with CpG as adjuvant were evaluated.Experimental Design: In a phase I clinical study, patients with advanced prostate cancer were vaccinated with recombinant NY-ESO-1 protein (100 μg) mixed with CpG 7909 (2.5 mg) every 3 weeks intradermally for 4 doses. Objectives of the study were the safety of the vaccine and changes of specific humoral and cellular immunological responses to NY-ESO-1 in relation to detectable NY-ESO-1 expression in the individual tumor.Results: All 12 baseline sero-negative patients developed high-titer NY-ESO-1 antibody responses. B-cell epitope mapping identified NY-ESO-1 p91–110 to be recognized most frequently by vaccine-induced antibodies. Two patients developed significant antibody titers against the adjuvant CpG. NY-ESO-1-specific CD4+ and/or CD8+ T-cell responses were induced in 9 patients (69%). Five of these 9 patients did not express NY-ESO-1 in the autologous tumor. Postvaccine CD8+ T-cell clones recognized and lyzed HLA-matched tumor cell lines in an antigen-specific manner.Conclusion: Our data provide clear evidence for the capacity of NY-ESO-1 protein/CpG vaccine to induce integrated antigen-specific immune responses in vivo and to efficiently prime CD8+ T-cell responses in NY-ESO-1 antigen-negative patients. Our results may also support further clinical vaccination protocols with NY-ESO-1 protein not only focused on the treatment of existing cancer, but also to prevent further development of NY-ESO-1 positive cancers in vivo. Clin Cancer Res; 17(4); 1–10. ©2010 AACR.

Supplementary Figure 4 from Efficacy of Levo-1-Methyl Tryptophan and Dextro-1-Methyl Tryptophan in Reversing Indoleamine-2,3-Dioxygenase–Mediated Arrest of T-Cell Proliferation in Human Epithelial Ovarian Cancer

Supplementary Figure 1 from Efficacy of Levo-1-Methyl Tryptophan and Dextro-1-Methyl Tryptophan in Reversing Indoleamine-2,3-Dioxygenase–Mediated Arrest of T-Cell Proliferation in Human Epithelial Ovarian Cancer

Supplementary Figure 2 from Efficacy of Levo-1-Methyl Tryptophan and Dextro-1-Methyl Tryptophan in Reversing Indoleamine-2,3-Dioxygenase–Mediated Arrest of T-Cell Proliferation in Human Epithelial Ovarian Cancer

Supplementary Figure 3 from Efficacy of Levo-1-Methyl Tryptophan and Dextro-1-Methyl Tryptophan in Reversing Indoleamine-2,3-Dioxygenase–Mediated Arrest of T-Cell Proliferation in Human Epithelial Ovarian Cancer

We previously found that a Salmonella typhimurium vector engineered to secrete soluble tumor antigen induces CD4+ T cells resistant to CD4+CD25+ regulatory T cells (Treg) and that glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) signal is involved in the development of this resistance. In this study, we address the potential of incorporating GITR ligand (GITRL) as a way to augment the immunogenicity of cancer vaccines. BALB/c mice were immunized by gene gun with plasmids encoding the mutated extracellular signal-regulated kinase 2 (mERK) with or without plasmids encoding mouse GITRL. Coadministration with GITRL during primary and secondary immunization enhanced the induction of mERK-specific CD8+ T cells. Antibody depletion and minigene analysis suggested that GITRL directly activated CTL epitope-specific CD8+ T cells independently of CD4+ T cells. Immunization with plasmids encoding a CTL epitope and GITRL resulted in strong tumor inhibition in a CD8+ T cell–dependent manner. Furthermore, CTL epitope-specific CD8+ T cells induced by immunization with plasmids encoding CTL epitope coadministered with GITRL were refractory to suppression by CD4+CD25+ Tregs compared with CD8+ T cells induced without GITR signaling. We propose that coadministration of GITR signaling agents with tumor antigens constitutes a promising novel strategy for cancer vaccine development. [Cancer Res 2008;68(14):5948–54]

Supplementary Materials, Legends for Figures 1-5 from Efficacy of Levo-1-Methyl Tryptophan and Dextro-1-Methyl Tryptophan in Reversing Indoleamine-2,3-Dioxygenase–Mediated Arrest of T-Cell Proliferation in Human Epithelial Ovarian Cancer