The importance of correctly timing cancer immunotherapy

INTRODUCTION

The treatment options for cancer-surgery, radiotherapy and chemotherapy-are now supplemented with immunotherapy. Previously underappreciated but now gaining strong interest are the immune modulatory properties of the three conventional modalities. Moreover, there is a better understanding of the needs and potential of the different immune therapeutic platforms. Key to improved treatment will be the combinations of modalities that complete each other's shortcomings. Area covered: Tumor-specific T-cells are required for optimal immunotherapy. In this review, the authors focus on the correct timing of different types of chemotherapeutic agents or immune modulators and immunotherapeutic drugs, not only for the activation and expansion of tumor-specific T-cells but also to support and enhance their anti-tumor efficacy. Expert opinion: At an early phase of disease, clinical success can be obtained using single treatment modalities but at later disease stages, combinations of several modalities are required. The gain in success is determined by a thorough understanding of the direct and indirect immune effects of the modalities used. Profound knowledge of these effects requires optimal tuning of immunomonitoring. This will guide the appropriate combination of treatments and allow for correct sequencing the order and interval of the different therapeutic modalities.

Standard radiotherapy but not chemotherapy impairs systemic immunity in non-small cell lung cancer

Introduction: Advanced non-small cell lung cancer (NSCLC) is traditionally treated with platinum-based chemotherapy and radiotherapy. Since immunotherapy holds promise for treating advanced NSCLC, we assessed the systemic effects of the traditional therapies for NSCLC on immune cell composition and function.

Methods: 84 pulmonary adenocarcinoma patients, treated either with chemotherapy or radiotherapy, were studied. A prospective study of 23 patients was conducted in which the myeloid and lymphoid cell compartments of peripheral blood were analyzed. Changes in cell populations were validated in a retrospective cohort of 61 adenocarcinoma patients using automated differential counts collected throughout therapy. Furthermore, the functional capacity of circulating T cells and antigen-presenting cells (APC) was studied. Blood samples of healthy individuals were used as controls.

Results: In comparison to healthy controls, untreated adenocarcinoma patients display an elevated frequency of myeloid cells coinciding with relative lower frequencies of lymphocytes and dendritic cells. Standard chemotherapy had no overt effects on myeloid and lymphoid cell composition nor on T-cell and APC-function. In contrast, patients treated with radiotherapy displayed a decrease in lymphoid cells and a relative increase in monocytes/macrophages. Importantly, these changes were associated with a reduced APC function and an impaired response of T cells to recall antigens.

Conclusions: Platinum-based standard of care chemotherapy for NSCLC has no profound negative effect on the immune cell composition and function. The negative effect of prolonged low-dose radiotherapy on the immune system warrants future studies on the optimal dose and fraction of radiotherapy when combined with immunotherapy.

Heterogeneity revealed by integrated genomic analysis uncovers a molecular switch in malignant uveal melanoma

Gene expression profiles as well as genomic imbalances are correlated with disease progression in uveal melanoma (UM). We integrated expression and genomic profiles to obtain insight into the oncogenic mechanisms in development and progression of UM. We used tumor tissue from 64 enucleated eyes of UM patients for profiling. Mutations and genomic imbalances were quantified with digital PCR to study tumor heterogeneity and molecular pathogenesis. Gene expression analysis divided the UM panel into three classes. Class I presented tumors with a good prognosis and a distinct genomic make up that is characterized by 6p gain. The UM with a bad prognosis were subdivided into class IIa and class IIb. These classes presented similar survival risks but could be distinguished by tumor heterogeneity. Class IIa presented homogeneous tumors while class IIb tumors, on average, contained 30% of non-mutant cells. Tumor heterogeneity coincided with expression of a set of immune genes revealing an extensive immune infiltrate in class IIb tumors. Molecularly, class IIa and IIb presented the same genomic configuration and could only be distinguished by 8q copy number. Moreover, UM establish in the void of the immune privileged eye indicating that in IIb tumors the infiltrate is attracted by the UM. Combined our data show that chromosome 8q contains the locus that causes the immune phentotype of UM. UM thereby provides an unique opportunity to study immune attraction by tumors.

The Breadth of Synthetic Long Peptide Vaccine-Induced CD8+ T Cell Responses Determines the Efficacy against Mouse Cytomegalovirus Infection

There is an ultimate need for efficacious vaccines against human cytomegalovirus (HCMV), which causes severe morbidity and mortality among neonates and immunocompromised individuals. In this study we explored synthetic long peptide (SLP) vaccination as a platform modality to protect against mouse CMV (MCMV) infection in preclinical mouse models. In both C57BL/6 and BALB/c mouse strains, prime-booster vaccination with SLPs containing MHC class I restricted epitopes of MCMV resulted in the induction of strong and polyfunctional (i.e., IFN-γ⁺, TNF⁺, IL-2⁺) CD8⁺ T cell responses, equivalent in magnitude to those induced by the virus itself. SLP vaccination initially led to the formation of effector CD8⁺ T cells (KLRG1^hi, CD44^hi, CD127^lo, CD62L^lo), which eventually converted to a mixed central and effector-memory T cell phenotype. Markedly, the magnitude of the SLP vaccine-induced CD8⁺ T cell response was unrelated to the T cell functional avidity but correlated to the naive CD8⁺ T cell precursor frequency of each epitope. Vaccination with single SLPs displayed various levels of long-term protection against acute MCMV infection, but superior protection occurred after vaccination with a combination of SLPs. This finding underlines the importance of the breadth of the vaccine-induced CD8⁺ T cell response. Thus, SLP-based vaccines could be a potential strategy to prevent CMV-associated disease.

The majority of infections with the betaherpesvirus human cytomegalovirus (HCMV) are clinically unnoticed, but in immunocompromised hosts HCMV infections can be severe and even fatal. Here we investigated in preclinical mouse models the efficacy and mechanisms of synthetic long peptide (SLP)-based vaccines eliciting mouse CMV (MCMV)-specific CD8⁺ T cells as a platform modality to protect against CMV infection. The percentages of MCMV-specific T cells in the circulation elicited by prime-booster SLP vaccination were equivalent or higher compared to those induced by the virus itself. We further show that the naive T cell precursor frequency rather than the functional avidity of T cells predicts the magnitude of SLP-induced CD8⁺ T cell responses. Superior protection against MCMV infection depends strongly on the combined use of distinct SLP vaccines leading to broader viral-specific responses. This finding highlights the importance of the breadth of vaccine-induced CD8⁺ T cell responses.

Monitoring of the Immune Dysfunction in Cancer Patients

Immunotherapy shows promising clinical results in patients with different types of cancer, but its full potential is not reached due to immune dysfunction as a result of several suppressive mechanisms that play a role in cancer development and progression. Monitoring of immune dysfunction is a prerequisite for the development of strategies aiming to alleviate cancer-induced immune suppression. At this point, the level at which immune dysfunction occurs has to be established, the underlying mechanism(s) need to be known, as well as the techniques to assess this. While it is relatively easy to measure general signs of immune suppression, it turns out that accurate monitoring of the frequency and function of immune-suppressive cells is still difficult. A lack of truly specific markers, the phenotypic complexity among suppressive cells of the same lineage, but potentially with different functions and functional assays that may not cover every mechanistic aspect of immune suppression are among the reasons complicating proper assessments. Technical innovations in flow and mass cytometry will allow for more complete sets of markers to precisely determine phenotype and associated function. There is, however, a clear need for functional assays that recapitulate more of the mechanisms employed to suppress the immune system.

Tumor Eradication by Cisplatin Is Sustained by CD80/86-Mediated Costimulation of CD8+ T Cells

Certain cytotoxic chemotherapeutic drugs are immunogenic, stimulating tumor immunity through mechanisms that are not completely understood. Here we show how the DNA-damaging drug cisplatin modulates tumor immunity. At the maximum tolerated dose (MTD), cisplatin cured 50% of mice with established murine TC-1 or C3 tumors, which are preclinical models of human papillomavirus (HPV)-associated cancer. Notably, the curative benefit of cisplatin relied entirely upon induction of tumor-specific CD8⁺ T cells. Mechanistic investigations showed that cisplatin stimulated tumor infiltration of inflammatory antigen-presenting cells (APC) expressing relatively higher levels of the T-cell costimulatory ligands CD70, CD80, and CD86. Cell death triggered by cisplatin was associated with the release of at least 19 proteins in the tumor environment that could act as damage-associated molecular patterns and upregulate costimulatory molecules, either alone or in concert, but the responsible proteins remain unknown. Essentially, the curative effect of cisplatin was abrogated in mice lacking expression of CD80 and CD86 on APCs. Furthermore, cisplatin treatment was improved by CTLA-4 blockade, which increases the availability of CD80/86 to bind to CD28. In contrast, there was no effect of CD27 stimulation, which replaces CD70 interaction. At the cisplatin MTD, cure rates could also be increased by vaccination with synthetic long peptides, whereas cures could also be achieved at similar rates at 80% of the MTD with reduced side effects. Our findings reveal an essential basis for the immunogenic properties of cisplatin, which are mediated by the induction of costimulatory signals for CD8⁺ T-cell-dependent tumor destruction. Cancer Res; 76(20); 6017-29. ©2016 AACR.

A phase 1/2 study combining gemcitabine, Pegintron and p53 SLP vaccine in patients with platinum-resistant ovarian cancer

Purpose

Preclinical tumor models show that chemotherapy has immune modulatory properties which can be exploited in the context of immunotherapy. The purpose of this study was to determine the feasibility and immunogenicity of combinations of such an immunomodulatory chemotherapeutic agent with immunotherapy, p53 synthetic long peptide (SLP) vaccine and Pegintron (IFN-α) in patients with platinum-resistant p53-positive epithelial ovarian cancer (EOC).

Experimental design

This is a phase 1/2 trial in which patients sequential 6 cycles of gemcitabine (1000 mg/kg² iv; n = 3), gemcitabine with Pegintron before and after the first gemcitabine cycle (Pegintron 1 μg/kg sc; n = 6), and gemcitabine and Pegintron combined with p53 SLP vaccine (0.3 mg/peptide, 9 peptides; n = 6). At baseline, 22 days after the 2^nd and 6^th cycle, blood was collected for immunomonitoring. Toxicity, CA-125, and radiologic response were evaluated after 3 and 6 cycles of chemotherapy.

Results

None of the patients enrolled experienced dose-limiting toxicity. Predominant grade 3/4 toxicities were nausea/vomiting and dyspnea. Grade 1/2 toxicities consisted of fatigue (78%) and Pegintron-related flu-like symptoms (72%). Gemcitabine reduced myeloid-derived suppressor cells (p = 0.0005) and increased immune-supportive M1 macrophages (p = 0.04). Combination of gemcitabine and Pegintron stimulated higher frequencies of circulating proliferating CD4+ and CD8+ T-cells but not regulatory T-cells. All vaccinated patients showed strong vaccine-induced p53-specific T-cell responses.

Conclusion

Combination of gemcitabine, the immune modulator Pegintron and therapeutic peptide vaccination is a viable approach in the development of combined chemo-immunotherapeutic regimens to treat cancer.

Targeting of the MAPK and AKT pathways in conjunctival melanoma shows potential synergy

PURPOSE

Conjunctival melanoma (CM) is a rare but lethal form of cancer. Similar to cutaneous melanoma, CM frequently carries activating mutations in BRAF and NRAS. We studied whether CM as well as conjunctival benign and premalignant melanocytic lesions express targets in the mitogen-activated protein kinase (MAPK) and AKT pathways, and whether specific inhibitors can suppress CM growth in vitro.

METHODS

131 conjunctival lesions obtained from 129 patients were collected. The presence of BRAF V600E mutation and expression of phosphorylated (p)-ERK and p-AKT were assessed by immunohistochemistry. We studied cell proliferation, phosphorylation, cell cycling and apoptosis in three CM cell lines using two BRAF inhibitors (Vemurafenib and Dabrafenib), a MEK inhibitor (MEK162) and an AKT inhibitor (MK2206).

RESULTS

The BRAF V600E mutation was present in 19% of nevi and 26% of melanomas, but not in primary acquired melanosis (PAM). Nuclear and cytoplasmic p-ERK and p-AKT were expressed in all conjunctival lesions. Both BRAF inhibitors suppressed growth of both BRAF mutant CM cell lines, but only one induced cell death. MEK162 and MK2206 inhibited proliferation of CM cells in a dose-dependent manner, and the combination of these two drugs led to synergistic growth inhibition and cell death in all CM cell lines.

CONCLUSION

ERK and AKT are constitutively activated in conjunctival nevi, PAM and melanoma. While BRAF inhibitors prohibited cell growth, they were not always cytotoxic. Combining MEK and AKT inhibitors led to more growth inhibition and cell death in CM cells. The combination may benefit patients suffering from metastatic conjunctival melanoma.

Abstract 5035A: Intratumoral HPV16-specific T-cells determine clinical outcome of HPV16+ oropharyngeal carcinomas

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer. While the number of HNSCC cases is decreasing, the number of oropharyngeal SCC (OSCC) is rising, especially in young adults. OSCC are increasingly (45-90%) caused by human papillomavirus type 16 (HPV16). Intriguingly, patients with HPV-induced OSCC respond better to therapy than HPV-negative OSCC. This is independent of nodal status, age, stage, tumor differentiation or gender. We hypothesized that the expression of the viral antigens E6 and E7 in HPV16+ OSCC equips the immune system with two strong tumor-specific antigens resulting in the development of a type 1 T-cell immune contexture supporting the better response of HPV+ OSCC to standard therapy.

To test our hypothesis we studied 87 patients with OSCC. The tumors of these patients were tested for the presence of HPV by GP5+/6+ PCR and the expression of p16 by immunohistochemistry. Moreover, fresh tumor tissue was dispersed, cryopreserved and subsequently used for in-depth analyses regarding the composition of the leukocyte infiltrates using a large set of antibodies either by CyTOF or BD Fortessa. In addition, T-cell reactivity was tested directly ex vivo and after a short-term culture period.

57% of OSCC patients were HPV16+ and they showed the best overall survival (p<0.0001, HR 6.9). Whereas none of 37 HPV-negative patients displayed intratumoral HPV16 E6/E7-specific T-cell reactivity this was detected in 25 of 40 (63%) HPV16+ OSCC. Notably, for most patients these T-cells were already detectable directly ex vivo, indicative for their activity in vivo. The presence of intratumoral HPV16-specific T-cell reactivity for the response of patients to therapy was extremely important for a better clinical outcome (p = 0.0003, HR 23.9) as estimated by Kaplan-Meier curves and log-rank analysis. Division of HPV16+ patients on the basis of p16 expression revealed that p16+ patients had a much better clinical outcome (p<0.0001, HR 11.8). In line with the notion that overexpression of p16 is directly associated with expression of the HPV16 E6 and E7 oncogenes, a strong association between p16 expression and HPV16-specific TIL reactivity was found (p<0.0001).

Mechanistically, we found that OSCC cell lines promoted the differentiation of monocytes to M2 macrophages. In vitro experiments showed that the presence of HPV-specific T-cell secreted cytokines prevented this and was even able to redifferentiate macrophages into better antigen-presenting cells, both phenotypically (including co-stimulatory molecules) and functionally (more IL-12 and less IL-10 production). In addition, these cytokines mediated a direct effect on the tumor cell proliferation and metabolism, thereby slowing down tumor growth as well as changing their impact on myeloid cells in the tumor microenvironment.

In conclusion, HPV-specific T cells elicited by HPV+ OSCC are highly predictive for response to therapy.

Citation Format: Marij J. Welters, Lilly-Ann van der Velden, Vanessa J. van Ham, Ilina Ehsan, Renske Goedemans, Saskia J. Santegoets, Sjoerd H. van der Burg. Intratumoral HPV16-specific T-cells determine clinical outcome of HPV16+ oropharyngeal carcinomas. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5035A.

Vaccines for established cancer: overcoming the challenges posed by immune evasion

Therapeutic vaccines preferentially stimulate T cells against tumour-specific epitopes that are created by DNA mutations or oncogenic viruses. In the setting of premalignant disease, carcinoma in situ or minimal residual disease, therapeutic vaccination can be clinically successful as monotherapy; however, in established cancers, therapeutic vaccines will require co-treatments to overcome immune evasion and to become fully effective. In this Review, we discuss the progress that has been made in overcoming immune evasion controlled by tumour cell-intrinsic factors and the tumour microenvironment. We summarize how therapeutic benefit can be maximized in patients with established cancers by improving vaccine design and by using vaccines to increase the effects of standard chemotherapies, to establish and/or maintain tumour-specific T cells that are re-energized by checkpoint blockade and other therapies, and to sustain the antitumour response of adoptively transferred T cells.

A beneficial tumor microenvironment in oropharyngeal squamous cell carcinoma is characterized by a high T cell and low IL-17(+) cell frequency

Patients with HPV-positive oropharyngeal squamous cell carcinomas (OPSCCs) have a better prognosis than patients with non-HPV-induced OPSCC. The role of the immune response in this phenomenon is yet unclear. We studied the number of T cells, regulatory T cells (Tregs), T helper 17 (Th17) cells and IL-17⁺ non-T cells (mainly granulocytes) in matched HPV-positive and HPV-negative OPSCC cases (n = 162). Furthermore, the production of IFN-γ and IL-17 by tumor-infiltrating T cells was analyzed. The number of tumor-infiltrating T cells and Tregs was higher in HPV-positive than HPV-negative OPSCC (p < 0.0001). In contrast, HPV-negative OPSCC contained significantly higher numbers of IL-17⁺ non-T cells (p < 0.0001). Although a high number of intra-tumoral T cells showed a trend toward improved survival of all OPSCC patients, their prognostic effect in patients with a low number of intra-tumoral IL-17⁺ non-T cells was significant with regard to disease-specific (p = 0.033) and disease-free survival (p = 0.012). This suggests that a high frequency of IL-17⁺ non-T cells was related to a poor immune response, which was further supported by the observation that a high number of T cells was correlated with improved disease-free survival in the HPV-positive OPSCC (p = 0.008). In addition, we detected a minor Th17 cell population. However, T cells obtained from HPV-positive OPSCC produced significantly more IL-17 than those from HPV-negative tumors (p = 0.006). The improved prognosis of HPV-positive OPSCC is thus correlated with higher numbers of tumor-infiltrating T cells, more active Th17 cells and lower numbers of IL-17⁺ non-T cells.

Toward harmonized phenotyping of human myeloid-derived suppressor cells by flow cytometry: results from an interim study

There is an increasing interest for monitoring circulating myeloid-derived suppressor cells (MDSCs) in cancer patients, but there are also divergences in their phenotypic definition. To overcome this obstacle, the Cancer Immunoguiding Program under the umbrella of the Association of Cancer Immunotherapy is coordinating a proficiency panel program that aims at harmonizing MDSC phenotyping. After a consultation period, a two-stage approach was designed to harmonize MDSC phenotype. In the first step, an international consortium of 23 laboratories immunophenotyped 10 putative MDSC subsets on pretested, peripheral blood mononuclear cells of healthy donors to assess the level of concordance and define robust marker combinations for the identification of circulating MDSCs. At this stage, no mandatory requirements to standardize reagents or protocols were introduced. Data analysis revealed a small intra-laboratory, but very high inter-laboratory variance for all MDSC subsets, especially for the granulocytic subsets. In particular, the use of a dead-cell marker altered significantly the reported percentage of granulocytic MDSCs, confirming that these cells are especially sensitive to cryopreservation and/or thawing. Importantly, the gating strategy was heterogeneous and associated with high inter-center variance. Overall, our results document the high variability in MDSC phenotyping in the multicenter setting if no harmonization/standardization measures are applied. Although the observed variability depended on a number of identified parameters, the main parameter associated with variation was the gating strategy. Based on these findings, we propose further efforts to harmonize marker combinations and gating parameters to identify strategies for a robust enumeration of MDSC subsets.

Vaccination against Oncoproteins of HPV16 for Noninvasive Vulvar/Vaginal Lesions: Lesion Clearance Is Related to the Strength of the T-Cell Response

PURPOSE

Therapeutic vaccination with human papillomavirus type 16 (HPV16) E6 and E7 synthetic long peptides (SLP) is effective against HPV16-induced high-grade vulvar and vaginal intraepithelial neoplasia (VIN/VaIN). However, clinical nonresponders displayed weak CD8(+) T-cell reactivity. Here, we studied if imiquimod applied at the vaccine site could improve CD8(+) T-cell reactivity, clinical efficacy, and safety of HPV16-SLP (ISA101).

EXPERIMENTAL DESIGN

A multicenter open-label, randomized controlled trial was conducted in patients with HPV16(+) high-grade VIN/VaIN. Patients received ISA101 vaccination with or without application of 5% imiquimod at the vaccine site. The primary objective was the induction of a directly ex vivo detectable HPV16-specific CD8(+) T-cell response. The secondary objectives were clinical responses (lesion size, histology, and virology) and their relation with the strength of vaccination-induced immune responses.

RESULTS

Forty-three patients were assigned to either ISA101 with imiquimod (n = 21) or ISA101 only (n = 22). Imiquimod did not improve the outcomes of vaccination. However, vaccine-induced clinical responses were observed in 18 of 34 (53%; 95% CI, 35.1-70.2) patients at 3 months and in 15 of 29 (52%; 95% CI, 32.5-70.6) patients, 8 of whom displayed a complete histologic response, at 12 months after the last vaccination. All patients displayed vaccine-induced T-cell responses, which were significantly stronger in patients with complete responses. Importantly, viral clearance occurred in all but one of the patients with complete histologic clearance.

CONCLUSIONS

This new study confirms that clinical efficacy of ISA101 vaccination is related to the strength of vaccine-induced HPV16-specific T-cell immunity and is an effective therapy for HPV16-induced high-grade VIN/VaIN. Clin Cancer Res; 22(10); 2342-50. ©2016 AACRSee related commentary by Karaki et al., p. 2317.

TAP-independent self-peptides enhance T cell recognition of immune-escaped tumors

Tumor cells frequently escape from CD8+ T cell recognition by abrogating MHC-I antigen presentation. Deficiency in processing components, like the transporter associated with antigen processing (TAP), results in strongly decreased surface display of peptide/MHC-I complexes. We previously identified a class of hidden self-antigens known as T cell epitopes associated with impaired peptide processing (TEIPP), which emerge on tumor cells with such processing defects. In the present study, we analyzed thymus selection and peripheral behavior of T cells with specificity for the prototypic TEIPP antigen, the "self" TRH4 peptide/Db complex. TEIPP T cells were efficiently selected in the thymus, egressed with a naive phenotype, and could be exploited for immunotherapy against immune-escaped, TAP-deficient tumor cells expressing low levels of MHC-I (MHC-Ilo). In contrast, overt thymus deletion and functionally impaired TEIPP T cells were observed in mice deficient for TAP1 due to TEIPP antigen presentation on all body cells in these mice. Our results strongly support the concept that TEIPPs derive from ubiquitous, nonmutated self-antigens and constitute a class of immunogenic neoantigens that are unmasked during tumor immune evasion. These data suggest that TEIPP-specific CD8+ T cells are promising candidates in the treatment of tumors that have escaped from conventional immunotherapies.

Human papillomavirus 16-specific cell-mediated immunity in children born to mothers with incident cervical intraepithelial neoplasia (CIN) and to those constantly HPV negative

Objectives

HPV infections are detected in sexually naive children. This has raised the question about the role of early HPV infections in either protecting or predisposing to further HPV infections. HPV16-specific cell-mediated immunity (CMI) was studied in 10 case-children born to mothers with an incident cervical intraepithelial neoplasia (CIN) diagnosed during their 14-year follow-up (FU), and in 21 children born to mothers, who remained constantly HPV-negative (controls). The mean age of children was 12.3 years.

Methods

Peripheral blood mononuclear cells were isolated from blood and stimulated with peptide pools covering HPV16 E2, E6 and E7. Proliferation of lymphocytes, their secretion of cytokines, and the frequency of regulatory T-cells were determined. The results were correlated with the HPV status and analyzed in a nested case–control setting.

Results

All children, except two controls, displayed CMI against HPV16 E2, E6 and/or E7 peptides associated with type 1 and 2 cytokine secretion. Only two statistically significant differences were found in the nested case–control setting; (1) case-children had a higher TNF-α response to HPV16 E2 (p = 0.004) than controls and (2) controls had no response to HPV16 E7.2 peptide pool while 3/10 case-children had (p = 0.013). Totally, 50 and 57 % of the cases and controls, respectively, had HPV positive oral samples at some FU-visit. In addition, the children without any HPV antibodies before the age of 6 months showed proliferative responses of PBMC after HPV16 exposure more frequently than other children (p = 0.045).

Conclusions

HPV16-specific CMI is common in young, sexually inexperienced children. This suggests that oral HPV infections occur frequently in children. Our results might also explain the previous findings that half of healthy adults demonstrate HPV-specific CMI irrespective of their partner/sexual status.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0733-4) contains supplementary material, which is available to authorized users.

Monitoring regulatory T cells in clinical samples: consensus on an essential marker set and gating strategy for regulatory T cell analysis by flow cytometry

Regulatory T cell (Treg)-mediated immunosuppression is considered a major obstacle for successful cancer immunotherapy. The association between clinical outcome and Tregs is being studied extensively in clinical trials, but unfortunately, no consensus has been reached about (a) the markers and (b) the gating strategy required to define human Tregs in this context, making it difficult to draw final conclusions. Therefore, we have organized an international workshop on the detection and functional testing of Tregs with leading experts in the field, and 40 participants discussing different analyses and the importance of different markers and context in which Tregs were analyzed. This resulted in a rationally composed ranking list of "Treg markers". Subsequently, the proposed Treg markers were tested to get insight into the overlap/differences between the most frequently used Treg definitions and their utility for Treg detection in various human tissues. Here, we conclude that the CD3, CD4, CD25, CD127, and FoxP3 markers are the minimally required markers to define human Treg cells. Staining for Ki67 and CD45RA showed to provide additional information on the activation status of Tregs. The use of markers was validated in a series of PBMC from healthy donors and cancer patients, as well as in tumor-draining lymph nodes and freshly isolated tumors. In conclusion, we propose an essential marker set comprising antibodies to CD3, CD4, CD25, CD127, Foxp3, Ki67, and CD45RA and a corresponding robust gating strategy for the context-dependent analysis of Tregs by flow cytometry.

The tumor area occupied by Tbet+ cells in deeply invading cervical cancer predicts clinical outcome

Background

Deep invasion of the normal surrounding tissue by primary cervical cancers is a prognostic parameter for postoperative radiotherapy and relatively worse survival. However, patients with tumor-specific immunity in the blood at the time of surgery displayed a much better disease free survival. Here we analyzed if this was due to a more tumor-rejecting immune population in the tumor.

Methods

Tumor sections from a group of 58 patients with deep normal tissue-invading cervical tumors were stained for the presence of immune cells (CD45), IFNγ-producing cells (Tbet) and regulatory T cells (Foxp3) by immunohistochemistry. The slides were scanned and both the tumor area and the infiltration of the differently stained immune cells were objectively quantified using computer software.

Results

We found that an increased percentage of tumor occupied by CD45+ cells was strongly associated with an enhanced tumor-infiltration by Tbet+ cells and Foxp3+ cells. Furthermore, the area occupied by CD45+ immune cells, Tbet+ cells but not Foxp3+ cells within the tumor were, in addition to the lymph node status of patients, associated with a longer disease free survival and disease specific survival. Moreover, interaction analyses between these immune parameters and lymph node status indicated an independent prognostic effect of tumor infiltrating Tbet+ cells. This was confirmed in a multivariate Cox analysis.

Conclusions

The area occupied by a preferentially type I oriented CD45+ cell infiltrate forms an independent prognostic factor for recurrence-free and disease-specific survival on top of the patient’s lymph node status.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0664-0) contains supplementary material, which is available to authorized users.

Abstract 2494: Vaccine-induced TNF alpha producing T cells synergize with cisplatin in tumor eradication

Previously we have shown that Synthetic Long Peptide (SLP) vaccination against Human Papilloma Virus (HPV) oncogenic proteins is safe and induces functional T-cell responses in mice and humans. Although vaccination induces potent clinical responses in mice and in patients with premalignant lesions, no clinical responses were observed in patients with cervical cancer. Here we show in a preclinical mouse model for HPV induced malignancies that SLP vaccination can be safely combined with clinically relevant chemotherapeutics to eradicate tumors. In mice that received either peptide vaccination or chemotherapy, only a temporary regression in tumor size was observed. Importantly, combined chemo-immunotherapy induced complete and sustained tumor eradication in nearly all mice. The chemotherapeutic agent cisplatin displayed the strongest synergy with SLP vaccination. Long term regression of tumors occurred at both the maximal tolerated dose of cisplatin and at 40% of that dose when combined with SLP vaccination, but at the later dose side effects such as body weight loss were absent. Upon vaccination tumors were highly infiltrated with Tumor Necrosis Factor alpha (TNFα) and Interferon gamma (IFN-γ) producing CD8+ CTLs. Tumor cells incubated with these cytokines and cisplatin in vitro strongly enhance their chemokine expression, compatible with the abundant leukocyte infiltration into the tumor upon combined chemo-immunotherapy. Accordingly, when combined with cisplatin treatment, SLP vaccine-induced CTLs appeared to migrate earlier from the tumor rim into the tumor beds. Moreover, analysis of the tumor cells in vivo showed that combined treatment significantly decreased the proliferative capacity of tumor cells compared to single treated or untreated tumors. Furthermore, we showed that TNFα enhanced cisplatin- induced, JNK dependent tumor cell apoptosis. This cell death was accompanied by an increased expression of pro-apoptotic molecules. The synergy between cisplatin and SLP vaccination was largely abolished by in vivo treatment with monoclonal antibody against TNFα. Together, our data show that combined peptide treatment with cisplatin leads to superior tumor eradication in the absence of T cell immunosuppression.

Citation Format: Cornelis J. Melief, Tetje C. van der Sluis, Sjoerd H. van der Burg. Vaccine-induced TNF alpha producing T cells synergize with cisplatin in tumor eradication. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2494. doi:10.1158/1538-7445.AM2015-2494

Therapeutic cancer vaccines

The clinical benefit of therapeutic cancer vaccines has been established. Whereas regression of lesions was shown for premalignant lesions caused by HPV, clinical benefit in cancer patients was mostly noted as prolonged survival. Suboptimal vaccine design and an immunosuppressive cancer microenvironment are the root causes of the lack of cancer eradication. Effective cancer vaccines deliver concentrated antigen to both HLA class I and II molecules of DCs, promoting both CD4 and CD8 T cell responses. Optimal vaccine platforms include DNA and RNA vaccines and synthetic long peptides. Antigens of choice include mutant sequences, selected cancer testis antigens, and viral antigens. Drugs or physical treatments can mitigate the immunosuppressive cancer microenvironment and include chemotherapeutics, radiation, indoleamine 2,3-dioxygenase (IDO) inhibitors, inhibitors of T cell checkpoints, agonists of selected TNF receptor family members, and inhibitors of undesirable cytokines. The specificity of therapeutic vaccination combined with such immunomodulation offers an attractive avenue for the development of future cancer therapies.

Managing Multi-center Flow Cytometry Data for Immune Monitoring

With the recent results of promising cancer vaccines and immunotherapy1–5, immune monitoring has become increasingly relevant for measuring treatment-induced effects on T cells, and an essential tool for shedding light on the mechanisms responsible for a successful treatment. Flow cytometry is the canonical multi-parameter assay for the fine characterization of single cells in solution, and is ubiquitously used in pre-clinical tumor immunology and in cancer immunotherapy trials. Current state-of-the-art polychromatic flow cytometry involves multi-step, multi-reagent assays followed by sample acquisition on sophisticated instruments capable of capturing up to 20 parameters per cell at a rate of tens of thousands of cells per second. Given the complexity of flow cytometry assays, reproducibility is a major concern, especially for multi-center studies. A promising approach for improving reproducibility is the use of automated analysis borrowing from statistics, machine learning and information visualization21–23, as these methods directly address the subjectivity, operator-dependence, labor-intensive and low fidelity of manual analysis. However, it is quite time-consuming to investigate and test new automated analysis techniques on large data sets without some centralized information management system. For large-scale automated analysis to be practical, the presence of consistent and high-quality data linked to the raw FCS files is indispensable. In particular, the use of machine-readable standard vocabularies to characterize channel metadata is essential when constructing analytic pipelines to avoid errors in processing, analysis and interpretation of results. For automation, this high-quality metadata needs to be programmatically accessible, implying the need for a consistent Application Programming Interface (API). In this manuscript, we propose that upfront time spent normalizing flow cytometry data to conform to carefully designed data models enables automated analysis, potentially saving time in the long run. The ReFlow informatics framework was developed to address these data management challenges.

Cell mediated immunity against HPV16 E2, E6 and E7 peptides in women with incident CIN and in constantly HPV-negative women followed-up for 10-years

Background

Virus-specific cell-mediated immunity (CMI) plays a role in the outcome of genital HPV infections. To cast further light on the question why most women clear their HPV infection while others develop high-grade cervical intraepithelial neoplasia (CIN), we analyzed HPV16 E2-, E6- and E7 -specific CMI in women who developed CIN during a 10-year follow-up of the Finnish Family HPV cohort.

Methods

Overlapping 30–35 mer peptides covering the entire HPV16 E2-, E6- and E7 protein sequences were used for defining the lymphocyte proliferation capacity, cytokine production (IL-2, IL-5, IL-10, IL-17A, IFN-γ and TNF-α) and numbers of HPV16 -specific CD4+ CD25+ Foxp3+ regulatory T-cells in 10 women who developed CIN, and in 22 control women who tested constantly HPV-negative during the follow-up. HPV-specific CMI was related to the demographic data including sexual behavior, smoking and alcohol consumption.

Results

Women with CIN and their controls had similar T-cell mediated immunity against HPV16 E2, E6 and E7 peptide pools. However, nearly fourfold higher T-cell reactivity against common antigens was found in the CIN women than in the healthy donors (p = 0.001). HPV16 E6 stimulation resulted in higher IL-17A secretion in the controls than in the CIN women (p = 0.035). Smoking and use of alcohol affected the T-cell response to common antigens but not to HPV peptides (p = 0.032 and 0.045, respectively).

Conclusion

While both the CIN women and controls exhibited an HPV16-specific CMI, IL-17A might be of importance in HPV induced pathology. The hyper-responsiveness of the CIN patients to common antigens needs further studies. Smoking and alcohol had no effect on HPV-specific CMI.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0498-9) contains supplementary material, which is available to authorized users.