A5 GM-CSF AUTOANTIBODIES: PREDICTORS OF CROHN’S DISEASE DEVELOPMENT AND A NOVEL THERAPEUTIC APPROACH

Background

Crohn’s disease (CD) is a heterogenous, chronic inflammatory disorder driven by a combination of genetic, environmental, and microbiota-dependent risk factors. Mononuclear phagocytes (MNP) are crucial cells that maintain intestinal homeostasis. An important cytokine for MNP survival and function is granulocyte-macrophage colony stimulating factor (GM-CSF). Interestingly, several studies reported CD-associated genetic risk variants within the GM-CSF receptor and its downstream signaling components. Furthermore, high titers of autoantibodies specific to GM-CSF can be detected in CD patients. Taken together, this data suggests an important role for GM-CSF in abrogation of CD development in a subgroup of patients.

Aims

This study sought to investigate the function of GM-CSF autoantibodies in CD.

Methods

We retrospectively quantified and characterized GM-CSF autoantibodies in sera of 220 CD, 200 ulcerative colitis (UC) patients, and 220 healthy controls (HC) sampled at 3 time points prior to disease diagnosis and one time point after diagnosis. ELISA was used to determine GM-CSF autoantibody titers and isotypes followed by in vitro multiplexed mass cytometry (CyTOF) neutralization assays on peripheral blood mononuclear cells. Flow cytometry and CyTOF were used to map the profile of immune cells isolated from inflamed and non-inflamed CD mucosa.

Results

Our data demonstrates that GM-CSF autoantibodies are specific to CD, significantly elevated up to 7 years prior to diagnosis of disease, and correlate with disease location, severity, and complications at the time of diagnosis. Moreover, in contrast to GM-CSF autoantibodies in pulmonary alveolar proteinosis patients, CD-associated autoantibodies neutralize GM-CSF via specific recognition of post-translational modifications (PTM), affecting MNP function. Removal of PTM enabled GM-CSF to escape autoantibody binding and restored MNP response to GM-CSF in the presence of neutralizing antibodies, indicating a potential therapeutic avenue. Furthermore, we identified group 3 innate lymphoid cells (ILC3) as a major source of GM-CSF in the healthy intestinal tract, suggesting intriguing crosstalk of MNP and ILC3 across the GM-CSF-GM-CSFR axis.

Conclusions

Our results identify GM-CSF autoantibodies as predictive serological biomarker for CD in a subgroup of patients presenting with severe and complicated form of disease at the time of diagnosis. The presence of GM-CSF autoantibodies precedes the onset of CD by several years and likely abrogates homeostatic immune cell crosstalk involving ILC3 and MNP, suggesting the development of a pre-diseased state in CD patients.

Funding Agencies

CIHRDr. Edward Ketchum Graduate Scholarship

Vaccination of stage III/IV melanoma patients with long NY-ESO-1 peptide and CpG-B elicits robust CD8+ and CD4+ T-cell responses with multiple specificities including a novel DR7-restricted epitope

Long synthetic peptides and CpG-containing oligodeoxynucleotides are promising components for cancer vaccines. In this phase I trial, 19 patients received a mean of 8 (range 1-12) monthly vaccines s.c. composed of the long synthetic NY-ESO-1_79-108 peptide and CpG-B (PF-3512676), emulsified in Montanide ISA-51. In 18/18 evaluable patients, vaccination induced antigen-specific CD8⁺ and CD4⁺ T-cell and antibody responses, starting early after initiation of immunotherapy and lasting at least one year. The T-cells responded antigen-specifically, with strong secretion of IFNγ and TNFα, irrespective of patients' HLAs. The most immunogenic regions of the vaccine peptide were NY-ESO-1_89-102 for CD8⁺ and NY-ESO-1_83-99 for CD4⁺ T-cells. We discovered a novel and highly immunogenic epitope (HLA-DR7/NY-ESO-1_87-99); 7/7 HLA-DR7⁺ patients generated strong CD4⁺ T-cell responses, as detected directly ex vivo with fluorescent multimers. Thus, vaccination with the long synthetic NY-ESO-1_79-108 peptide combined with the strong immune adjuvant CpG-B induced integrated, robust and functional CD8⁺ and CD4⁺ T-cell responses in melanoma patients, supporting the further development of this immunotherapeutic approach.

Abstract P4-06-01: Human mammary tumor virus, HMTV, is an MMTV-adapted human pathogen

Forty percent of American women's breast cancers contain HMTV, a betaretrovirus 90-98% homologous to MMTV, the causative agent for breast cancer in mice. HMTV is reverse-transcribed and integrated into chromosomal DNA of human breast cells. MMTV contamination of our analyses has been definitively excluded. In 8% of unselected American mothers HMTV is found in cells in milk, but in 21% of milks from women previously biopsied for unconfirmed cancer suspicion. In breasts biopsied for suspicion of cancer before a later diagnosis of breast cancer, we see suggestive morphologic changes if the subsequent breast cancer is HMTV+. HMTV is infectious in vitro for B and T lymphocytes, dendritic cells, and human mammary epithelial cells. Infecting MCF-10 breast cell lines with HMTV produces molecular changes of epithelial-mesenchymal transition with upregulation of vimentin ,and downregualtion of E-cadherin. The excess of breast cancer in western European countries and their former colonies (age standardized rates of 47 to 92 per 100,000 per year) compared to Asian incidence (29 to 43 ASR/y) can be explained by excess HMTV-related breast cancer incidence. In 7 West European, American and Oceania countries, 30 to 60% contain HMTV, while in 5 Asian nations HMTV in breast cancers ranges from 0 to 22% Different indigenous murine species with disparate MMTV burdens parallel these findings: mus domesticus in the West with much MMTV in its genome, and m. castaneus or m.musculus in the East with less. Ancient contamination of the food chain, and current lactational transfer perpetuate infection. HMTV poses a new and challenging dimension to breast cancer research involving diagnosis, molecular mechanisms, epidemiology, therapy and prevention.

Citation Format: Holland JF, Jaffer S, Melana S, Nartey T, Gnjatic S, Pogo BG-T. Human mammary tumor virus, HMTV, is an MMTV-adapted human pathogen. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-06-01.

Cancer-testis antigen expression and immunogenicity in AL amyloidosis

Light-chain amyloidosis (AL) is a plasma cell dyscrasia closely related to multiple myeloma. In multiple myeloma, the cancer-testis antigens (CTAs) CT7 (MAGE-C1), CT10 (MAGE-C2) and MAGE-A CTAs are expressed in up to 80% of cases. In this study, we investigated the expression and immunogenicity of several CTAs in patients with AL amyloidosis in a total of 38 bone marrow specimens by employing standard immunohistochemistry techniques on paraffin-embedded archival tissues. Plasma samples from 35 patients (27 with matched bone marrow samples) were also analyzed by ELISA for sero reactivity to a group of full-length CTA proteins. CT7 was present in 25/38 (66%) while CT10 was demonstrated in 3/38 and GAGE in 1/38 AL amyloid cases. The expression pattern was mostly focal. There were no significant differences with regard to organ involvement, response to treatment, or prognosis in CTA positive compared to negative cases. None of the specimens showed spontaneous humoral immunity to CT7, but sero reactivity was observed in individual patients to other CTAs. This study identifies CT7 as the prevalent CTA in plasma cells of patients with AL amyloidosis. Further analyses determining the biology of CTAs in AL amyloidosis and their value as potential targets for immunotherapy are warranted.

Imiquimod: A TLR-7 agonist as adjuvant for a recombinant protein cancer vaccine

8545

Purpose: This clinical trial evaluates the safety and adjuvant activity of imiquimod, a toll-like receptor (TLR)-7 agonist, when given with a NY-ESO-1 protein vaccine. Imiquimod, by locally activating and recruiting dendritic cells (DCs) into the skin, is expected to stimulate antigen uptake by DCs, induce maturation and migration to draining lymph nodes, and to induce antigen-specific T and B cell immunity. Methods: Pilot study; 9 patients with resected stage 2B-3C malignant melanoma. Four 21 day cycles consisted of topical imiquimod cream (250 mg) on days 1–5 and id. injected NY-ESO-1 protein (100 mcg) into the site on day 3. Blood was drawn at several time points for immune monitoring; skin punch biopsies were obtained from control, imiquimod and vaccination sites 48 hours after the last vaccination. Results: The regimen was tolerated well, all patients completed four vaccinations. AEs were mild and transient and included injection site reactions (8/9 patients), fatigue (4/9 patients) and fever (2/9 patients). Significant levels of antigen-specific CD4+ or CD8+ T cell responses were not detected in ex-vivo ELISPOT assays. However, intracellular cytokine staining assays after in vitro pre-stimulation indicated that 6 of 8 subjects developed NY-ESO-1 CD4+ T cell responses. Humoral immunity was manifest by the induction of anti-NY-ESO-1 antibodies in 7/9 patients post-vaccination. Histochemistry of skin sections showed significant dermal mononuclear cell infiltrates in Imiquimod treated skin, whereas none were seen in untreated skin (p<0.01). IHC revealed markedly increased numbers of CD3+ (T-cells), CD68+ (macrophages/monocytes), CD123+ (plasmacytoid DCs) and DC-LAMP+ (mature myeloid DCs) immune cells in Imiquimod treated skin when compared with control skin of the same patients (p<0.05). Conclusion: Imiquimod, a topical immune response modifier, generated clear inflammatory infiltrates in the dermis, with significant increases in antigen-presenting cells and T cells. Imiquimod was well tolerated when used as an adjuvant to an NY-ESO-1 protein vaccine. Systemic immunity of both humoral and cellular types was induced in the majority of patients; however, responses were weak and the vaccine combination needs to be optimized in future studies.

No significant financial relationships to disclose.

Booster vaccination of non-small cell lung cancer (NSCLC) patients with MAGEA3 protein and AS02B adjuvant

3015

Background: We have previously reported results of a phase II trial of recombinant ProtD/MAGE-3/His (MAGEA3) protein 300μg administered IM every three weeks for 4 doses with or without adjuvant AS02B to NSCLC patients following resection of MAGEA3 positive disease (JI, 172:3289, 2004). We found that the presence of adjuvant was essential for the development of strong humoral and cellular responses against selected MAGEA3 epitopes. Methods: 14 of the original 18 patients received booster vaccinations. Patients who still had no evidence of disease for up to two years after receiving their original MAGEA3 protein regimen (7 in cohort 1 without adjuvant, 7 in cohort 2 with adjuvant), received 4 additional doses of MAGEA3 protein with adjuvant. T cell immunomonitoring was extended to encompass any MAGEA3 epitope using full length antigen, and the scope of analysis of humoral responses was widened. Results: After just one boost injection, 6 of the 7 patients originally vaccinated with MAGEA3 protein plus adjuvant reached the peak of antibody titers to MAGEA3 attained during the first vaccination and went on to develop a stronger response than during the first cycle. In addition, the spectrum of CD4+ and CD8+ T cells against various new and known epitopes widened with booster vaccination. In contrast, only 3/7 patients originally vaccinated with MAGEA3 protein alone seroconverted to low-titered MAGEA3 responses and showed very limited CD4+ and no CD8+ T cell reactivity, despite now receiving antigen in the presence of adjuvant. Conclusions: These results underscore the importance of proper antigen priming using an adjuvant for generating persistent B and T cell memory, allowing for typical booster responses with re-immunization. In contrast, absence of adjuvant at priming may compromise further immunization attempts. These data provide immunological rationale for vaccine design in light of recently reported favorable clinical findings in NSCLC patients following vaccination with MAGEA3 protein plus adjuvant AS02B (GSK, ASCO 2005).

No significant financial relationships to disclose.

SOX2 antibody responses in patients with various tumor types and SCLC with and without paraneoplastic neurologic syndromes

2562

Background: SOX2, a member of the SOX Group B family of transcription factors, is expressed in normal adult brain, testis and prostate as well as in many SCLC cell lines. Spontaneous antibody responses to SOX2 have previously been shown to be detectable in SCLC patients. We undertook a retrospective study to determine whether antibody responses were detectable in patients with other malignancies and in patients with paraneoplastic neurologic syndromes (PND/PNS). Methods: Previously obtained serum samples from patients with no known disease (n = 84), breast and ovarian cancer (n = 35 each), melanoma (n = 42), NSCLC (n = 150), and SCLC patients, 90 from Turkey and 68 patients studied for PND, were tested by ELISA using serial 4-fold dilutions for anti-SOX2 and anti-HuD antibody. Results: Preliminary data shows SOX2 reactivity in 5/84 (6%) normal volunteer sera, 8/35 (23%) in both breast and ovarian cancer patients, 4/42 (9%) melanoma patients, 20/150 (13.3%) NSCLC patients, and 56/158 (35.4%) SCLC patients. Compared to controls, there was a statistically significant difference in SOX2 immunoreactivity in breast, ovarian (p = 0.007 for both) and SCLC patients (p < 0.001), and a trend was noted in NSCLC patients (p = 0.080). No breast, ovarian, melanoma or normal patient had SOX2 antibody titers ≥1:6400, compared with 32/56 (57.1%) of SCLC (p < 0.01) and 6/20 (30%) NSCLC patients (p < 0.16). Nine SCLC patients had neurologic symptoms and were previously found to have anti-HuD antibodies, associated with a diagnosis of PND. This was confirmed in 8/9 patients in our assay. However, none of the nine patients displayed anti-SOX2 reactivity. Eleven additional SCLC patients were found to be HuD positive by our ELISA. Conclusions: Anti-SOX2 responses are found in a significant proportion of patients with SCLC, breast and ovarian cancer, but not in melanoma patients compared to normal controls. Patients with SCLC have higher titer antibodies when compared with the other groups, and anti-SOX2 antibodies do not appear to associate with anti-HuD responses, supporting the hypothesis that SOX2 immune responses are not associated with PND and may be useful as a vaccine target. Supported by the Cancer and Leukemia Group B/Aventis Oncology Award and the Steps for Breath Foundation.

No significant financial relationships to disclose.

CD8+ tumor-infiltrating lymphocytes as a statistically significant marker of disease recurrence and survival in transitional cell carcinoma patients

4544

Background: Superficial transitional cell carcinoma (TCC) is an immune-responsive tumor evidenced by immunotherapy trials with BCG demonstrating improved survival. In contrast, more advanced muscle-invasive TCC is not considered an immunologically active tumor. Yet, host immune functions that may have a clinical impact on the biologic activity of these more invasive tumors have not been systemically evaluated. CD8+ T-cells are responsible for cytotoxicity and potential tumor eradication by interaction with antigen plus human leukocyte antigens (HLA). A clear association between intratumoral CD8+ T-cells and clinical outcome has not been established in TCC. Methods: We performed pathological, immunohistochemical and RT-PCR analyses of 69 TCC patient samples that were obtained with appropriate informed consent on an Institutional Review Board (IRB)-approved protocol. The samples were studied for pathological stage, tumor-associated antigen expression, class I HLA expression, and CD8+ intratumoral T-cells. Systemic CD8+ T-cells from one patient with positive CD8+ intratumoral T-cells were studied by tetramer analyses for reactivity against the NY-ESO-1 tumor antigen expressed on the patient’s tumor. Results: In a subset analysis, advanced TCC (pT2, pT3 and pT4) patients who had higher numbers of CD8+ tumor infiltrating lymphocytes (TILs) had a greater disease-free survival (p = 0.0002) and overall survival (p = 0.011) than similarly staged TCC patients with lower numbers of CD8+ TILs. In the multivariate analyses, CD8+ TILs (p = 0.04) and tumor stage (p < 0.001) were significant risk factors to predict overall survival. Furthermore, a CD8+ T-cell clone derived from one patient demonstrated strong recognition of the tumor antigen NY-ESO-1. Conclusions: This is the first report, to our knowledge, that CD8+ TILs is an important prognostic indicator for patients with advanced TCC. Investigational immunotherapy strategies to evoke CD8+ T-cell responses are warranted in patients with advanced TCC.

[Table: see text]

Phase I safety and immunogenicity study of NY-ESO-1b peptide and Montanide ISA-51 vaccination of patients with ovarian cancer (OC) in high risk first remission

5078

Background: The Cancer Testis (CT) antigen NY-ESO-1 is expressed in over 60% of advanced OC. NY-ESO-1 demonstrates strong immunogenicity and expression is restricted to gonadal tissues, making it an appealing immunologic target. Patients with high risk OC (suboptimal debulking, incomplete CA125 response at 3 cycles, or positive second look surgery) have a high recurrence rate, with median time to progression (TTP) of 10–12mos. Strategies to prolong remission are needed. Methods: After primary surgery and platinum based chemotherapy high risk HLA-A*0201 OC patients in first clinical remission received HLA-restricted NY-ESO-1b peptide (100 μg) and Montanide adjuvant (0.5mL) every 3 weeks for a total of 5 vaccinations. NY-ESO1 tumor expression was evaluated by immunohistochemistry (IHC). Toxicity using NCI-CTC v2 and immunogenicity: 1) NY-ESO-1 specific humoral immunity (ELISA); 2) NY-ESO-1 specific T-cell immunity (tetramer and ELISPOT); and 3) delayed type hypersensitivity (DTH) were assessed on weeks 0, 1, 4, 7, 10, 13, 16. Patients were monitored for progression of disease (POD). Results: Seventeen out of 46 (37%) screened patients were HLA-A*0201+. Eight of 10 enrolled patients have completed therapy, one patient is receiving treatment, and one patient was removed before initiation for POD. Treatment related adverse events (AEs) included: Grade 1 fatigue, anemia, pruritus, myalgias and hyperthyroidism and Grade 2 hypothyroidism. No Grade 3/4 AEs were seen. Five patients (50%) had NY-ESO-1+ tumor; 3 of 3 treated patients with NY-ESO1+ tumor demonstrated T cell immunity by positive tetramer (0.65%–9%) and ELISPOT (35–250 spots). Four of 5 (80%) treated patients with NY-ESO-1- tumor demonstrated T cell immunity by tetramer (1–12%) and/or ELISPOT (250–400 spots). There was no evidence of DTH reaction. With long-term followup 4 of 8 patients have recurred with median TTP of 8.5mos; 4 patients remain in complete remission at intervals of 9, 16, 22, and 37mos to date. Conclusion: Vaccination of high risk HLA A*0201+ OC patients with NY-ESO-1b and Montanide has manageable toxicity, and induces specific T cell immunity in patients with both NY-ESO-1 positive and negative tumors. Additional testing is warranted.

No significant financial relationships to disclose.

Immunophenotype of regionally recurrent melanoma of the extremity in patients before isolated limb infusion (ILI)

8052

Background: ILI is an effective, though palliative, treatment for patients with regionally recurrent melanoma of the extremity. Tumor-associated antigens such as the Cancer Testis (CT) antigens and melanocyte differentiation antigens (MDAs) have been used successfully as targets for vaccine-based immunotherapy trials in patients with recurrent melanoma. Little is known about expression of these antigens in patients with regional disease. Methods: Samples of regionally recurrent melanoma were obtained from patients prior to ILI as part of an ongoing clinical trial. 22 available samples were formalin-fixed, paraffin-embedded and analyzed by IHC for the following antigens (using the following monoclonal antibodies): CT antigens (MAGE-A1 [MA454], MAGE-A3 [M3H67], MAGE-A4 [57B], NY-ESO-1 [E978], CT7/MAGE-C1 [CT-33], GAGE) and MDAs (gp100 [HMB45], Melan-A/MART-1 [A103], tyrosinase [T311]). The presence of antibodies to CT antigens was analyzed by ELISA. Results: The antigen expression profile was as follows (positive/total): MAGE-A1 9/22 (41%); MAGE-A3 13/22 (59%), MAGE-A4 11/22 (50%), CT7 14/22 (64%), NY-ESO-1 8/22 (36%), GAGE 12/22 (55%), Melan-A 20/22 (91%), tyrosinase 20/22 (91%), gp100 19/22 (86%). The expression pattern was homogeneous for the vast majority of MDAs and for most CT antigens. No serologic response to any of the tested CT antigens was found in any of the patients. Conclusions: Regionally recurrent melanoma exhibits a homogeneous expression of melanocyte differentiation and CT antigens indicating expression similar to distant metastases. Despite the often prolonged course of patients with regionally recurrent disease, there is no evidence of an effective immune response to CT antigens.

No significant financial relationships to disclose.

Induction of primary NY-ESO-1 immunity: CD8+ T lymphocyte and antibody responses in peptide-vaccinated patients with NY-ESO-1+ cancers

Cancer-testis antigen NY-ESO-1 is one of the most immunogenic tumor antigens defined to date. Spontaneous humoral and CD8+ T-cell responses to NY-ESO-1 are detected in 40-50% of patients with advanced NY-ESO-1-expressing tumors. A clinical trial was initiated to study the immunological effects of intradermal vaccination with 3 HLA-A2-binding NY-ESO-1 peptides in 12 patients with metastatic NY-ESO-1-expressing cancers. Seven patients were NY-ESO-1 serum antibody negative, and five patients were NY-ESO-1 serum antibody positive at the outset of the study. Primary peptide-specific CD8+ T-cell reactions and delayed-type hypersensitivity responses were generated in four of seven NY-ESO-1 antibody-negative patients. Induction of a specific CD8+ T-cell response to NY-ESO-1 in immunized antibody-negative patients was associated with disease stabilization and objective regression of single metastases. NY-ESO-1 antibody-positive patients did not develop significant changes in baseline NY-ESO-1-specific T-cell reactivity. However, stabilization of disease and regression of individual metastases were observed in three of five immunized patients. These results demonstrate that primary NY-ESO-1-specific CD8+ T-cell responses can be induced by intradermal immunization with NY-ESO-1 peptides, and that immunization with NY-ESO-1 may have the potential to alter the natural course of NY-ESO-1-expressing tumors.

Strategy for monitoring T cell responses to NY-ESO-1 in patients with any HLA class I allele

NY-ESO-1 elicits frequent antibody responses in cancer patients, accompanied by strong CD8(+) T cell responses against HLA-A2-restricted epitopes. To broaden the range of cancer patients who can be assessed for immunity to NY-ESO-1, a general method was devised to detect T cell reactivity independent of prior characterization of epitopes. A recombinant adenoviral vector encoding the full cDNA sequence of NY-ESO-1 was used to transduce CD8-depleted peripheral blood lymphocytes as antigen-presenting cells. These modified antigen-presenting cells were then used to restimulate memory effector cells against NY-ESO-1 from the peripheral blood of cancer patients. Specific CD8(+) T cells thus sensitized were assayed on autologous B cell targets infected with a recombinant vaccinia virus encoding NY-ESO-1. Strong polyclonal responses were observed against NY-ESO-1 in antibody-positive patients, regardless of their HLA profile. Because the vectors do not cross-react immunologically, only responses to NY-ESO-1 were detected. The approach described here allows monitoring of CD8(+) T cell responses to NY-ESO-1 in the context of various HLA alleles and has led to the definition of NY-ESO-1 peptides presented by HLA-Cw3 and HLA-Cw6 molecules.

Identification of NY-ESO-1 peptide analogues capable of improved stimulation of tumor-reactive CTL

Expression of NY-ESO-1 in a high proportion of different human tumors makes this protein a very attractive vaccine target. NY-ESO-1 peptides, recognized by HLA-A2-restricted CTL, have recently been described. However, it remains unclear how efficiently tumors generate these epitopes, and whether peptide analogues can be used for optimal expansion and activation of NY-ESO-1-specific HLA-A2-restricted CTL. By generating unique CTL clones, we demonstrate that NY-ESO-1-positive tumor cells are efficiently killed by HLA-A2-restricted CTL specific for the peptide epitope NY-ESO-1 157-165. Presentation of this epitope is not affected by the presence or absence of the proteasome subunits low molecular proteins 2 and 7 and is not blocked by proteasome inhibitors, while it is impaired in the TAP-deficient cell line LBL 721.174. NY-ESO-1 157-165 peptide analogues were compared for their antigenicity and immunogenicity using PBL from melanoma patients. Three peptides, containing the carboxyl-terminal cysteine substituted for either valine, isoleucine, or leucine, were recognized at least 100 times more efficiently than the wild-type peptide by specific CTL. Peptide analogues were capable of stimulating the expansion of NY-ESO-1-specific CTL from PBL of melanoma patients much more efficiently than wild-type peptide. These findings define the processing requirements for the generation of the NY-ESO-1 157-165 epitope. Identification of highly antigenic NY-ESO-1 peptide analogues may be important for the development of vaccines capable of expanding NY-ESO-1-specific CTL in cancer patients.

Monitoring CD8 T cell responses to NY-ESO-1: correlation of humoral and cellular immune responses

NY-ESO-1, a member of the cancer-testis family of antigens, is expressed in a subset of a broad range of different human tumor types. Patients with advanced NY-ESO-1-expressing tumors frequently develop humoral immunity to NY-ESO-1, and three HLA A2-restricted peptides were defined previously as targets for cytotoxic CD8(+) T cells in a melanoma patient with NY-ESO-1 antibody. The objectives of the present study were (i) to develop enzyme-linked immunospot (ELISPOT) and tetramer assays to measure CD8(+) T cell responses to NY-ESO-1, (ii) to determine the frequency of CD8(+) T cell responses to NY-ESO-1 in a series of HLA-A2 patients with NY-ESO-1 expressing tumors, (iii) to determine the relation between CD8(+) T cell and humoral immune responses to NY-ESO-1, and (iv) to compare results of NY-ESO-1 ELISPOT assays performed independently in two laboratories with T cells from the same patients. NY-ESO-1 ELISPOT and tetramer assays with excellent sensitivity, specificity, and reproducibility have been developed and found to correlate with cytotoxicity assays. CD8(+) T cell responses to HLA-A2-restricted NY-ESO-1 peptides were detected in 10 of 11 patients with NY-ESO-1 antibody, but not in patients lacking antibody or in patients with NY-ESO-1-negative tumors. The results of ELISPOT assays were concordant in the two laboratories, providing the basis for standardized monitoring of T cell responses in patients receiving NY-ESO-1 vaccines.

Identification of NY-ESO-1 epitopes presented by human histocompatibility antigen (HLA)-DRB4*0101-0103 and recognized by CD4(+) T lymphocytes of patients with NY-ESO-1-expressing melanoma

NY-ESO-1 is a member of the cancer-testis family of tumor antigens that elicits strong humoral and cellular immune responses in patients with NY-ESO-1-expressing cancers. Since CD4(+) T lymphocytes play a critical role in generating antigen-specific cytotoxic T lymphocyte and antibody responses, we searched for NY-ESO-1 epitopes presented by histocompatibility leukocyte antigen (HLA) class II molecules. Autologous monocyte-derived dendritic cells of cancer patients were incubated with recombinant NY-ESO-1 protein and used in enzyme-linked immunospot (ELISPOT) assays to detect NY-ESO-1-specific CD4(+) T lymphocyte responses. To identify possible epitopes presented by distinct HLA class II alleles, overlapping 18-mer peptides derived from NY-ESO-1 were synthetized and tested for recognition by CD4(+) T lymphocytes in autologous settings. We identified three NY-ESO-1-derived peptides presented by DRB4*0101-0103 and recognized by CD4(+) T lymphocytes of two melanoma patients sharing these HLA class II alleles. Specificity of recognition was confirmed by proliferation assays. The characterization of HLA class II-restricted epitopes will be useful for the assessment of spontaneous and vaccine-induced immune responses of cancer patients against defined tumor antigens. Further, the therapeutic efficacy of active immunization using antigenic HLA class I-restricted peptides may be improved by adding HLA class II-presented epitopes.

Accumulation of the p53 protein allows recognition by human CTL of a wild-type p53 epitope presented by breast carcinomas and melanomas

The p53 protein is accumulated in tumor cells of many human cancers and can elicit in vivo humoral and proliferative responses. Rare reports about p53-mediated tumor recognition by CTLs have remained questioned. We therefore studied a panel of breast tumor and melanoma cell lines that we assayed for the presence of accumulated p53 and surface HLA-A2 and for the presentation of p53 epitopes. From PBMC of a healthy donor, we have generated a CTL line, D5/L9V, directed against HLA-A2-restricted peptide 264-272 from wild-type p53. It efficiently lysed breast adenocarcinomas MCF-7, MCF7/RA1, and MDA-MB-231, and melanoma M8, which all accumulate the p53 protein. Using competition assays, we made sure that tumor lysis by D5/L9V was due to recognition of endogenously produced p53 peptide 264-272 associated with the HLA-A2.1 molecule on the surface of these tumor cells. Cells with undetectable levels of wild-type p53, such as lymphoblastoid cells and melanoma M74, were not recognized by D5/L9V. Neither were breast tumor cell line MCF7/ADR nor melanoma line M44 because of HLA loss. This study therefore shows that it is possible to obtain in vitro CTL lines that specifically recognize a p53 epitope spontaneously presented by a variety of HLA-A2+ transformed cell lines provided they display abnormal patterns of p53 expression. This work points out that breast tumors and melanomas share a p53 epitope, and raises hopes for future immunotherapeutic approaches.

Mapping and ranking of potential cytotoxic T epitopes in the p53 protein: effect of mutations and polymorphism on peptide binding to purified and refolded HLA molecules

In many cancer cells, the p53 gene displays point mutations that result in stabilization and accumulation of the p53 protein. Therefore, p53 peptides could be presented to the immune system by tumor cells; thus, p53 might be a suitable target antigen for developing an immunotherapy against tumors using cytotoxic T lymphocytes (CTL). To map candidate CTL epitopes, we synthesized 150 peptides of 8-11 residues that contained putative anchor motifs required for binding to common HLA class I molecules. They were tested for their capacity to promote the assembly of purified and refolded HLA-A1, A2, B7 and B8 molecules. The following wild-type p53 peptides were found to be reactive with the HLA molecules tested: 196-205 and 226-234 bound moderately to HLA-A1; 25-35, 65-73, 129-137, 187-197, 263-272 and 264-272 bound strongly, and 187-195 and 256-264 moderately to HLA-A2; 26-35, 63-73, 189-197, 249-257 and 321-330 bound strongly to HLA-B7; and 135-143, 210-218 and 375-383 bound weakly to HLA-B8. We also analyzed the effects of p53 mutations occurring naturally in tumors on peptide/HLA assembly. We found substitutions that enhanced, diminished or had no effect on the peptide binding to HLA molecules. Polymorphism at position 72 mainly affected peptide/HLA-B7 binding, the proline allele P72 giving a less-reactive peptide (63-73) than the arginine allele R72. We have ranked potential p53 epitopes according to their reactivity for purified HLA molecules, allowing the selection of appropriate peptides and HLA molecules to attempt CTL induction in vitro.