Allogeneic NK cells induce the in vitro activation of monocyte-derived and conventional type-2 dendritic cells and trigger an inflammatory response under cancer-associated conditions.

Natural killer (NK) cells are innate lymphocytes capable to recognize and kill virus-infected and cancer cells. In the past years, the use of allogeneic NK cells as anti-cancer therapy gained interest due to their ability to induce graft-versus-cancer responses without causing graft-versus-host disease and multiple protocols have been developed to produce high numbers of activated NK cells. While the ability of these cells to mediate tumor kill has been extensively studied, less is known about their capacity to influence the activity of other immune cells that may contribute to a concerted anti-tumor response in the tumor microenvironment (TME). In this study, we analyzed how an allogeneic off-the-shelf cord blood stem cell-derived NK-cell product influenced the activation of dendritic cells (DC). Crosstalk between NK cells and healthy donor monocyte-derived DC (MoDC) resulted in the release of IFNγ and TNF, MoDC activation, and the release of the T-cell-recruiting chemokines CXCL9 and CXCL10. Moreover, in the presence of prostaglandin-E2, NK cell/MoDC crosstalk antagonized the detrimental effect of IL-10 on MoDC maturation leading to higher expression of multiple (co-)stimulatory markers. The NK cells also induced activation of conventional DC2 (cDC2) and CD8+ T cells, and the release of TNF, GM-CSF, and CXCL9/10 in peripheral blood mononuclear cells of patients with metastatic colorectal cancer. The activated phenotype of MoDC/cDC2 and the increased release of pro-inflammatory cytokines and T-cell-recruiting chemokines resulting from NK cell/DC crosstalk should contribute to a more inflamed TME and may thus enhance the efficacy of T-cell-based therapies.

Pre-treatment tumor-infiltrating T cells influence response to neoadjuvant chemoradiotherapy in esophageal adenocarcinoma.

Esophageal adenocarcinoma (EAC) is a disease with dismal treatment outcomes. Response to neoadjuvant chemoradiation (CRT) varies greatly. Although the underlying mechanisms of CRT resistance are not identified, accumulating evidence indicates an important role for local antitumor immunity. To explore the immune microenvironment in relation to response to CRT we performed an in-depth analysis using multiplex immunohistochemistry, flow cytometry and mRNA expression analysis (NanoString) to generate a detailed map of the immunological landscape of pretreatment biopsies as well as peripheral blood mononuclear cells (PBMCs) of EAC patients. Response to CRT was assessed by Mandard's tumor regression grade (TRG), disease-free- and overall survival. Tumors with a complete pathological response (TRG 1) to neoadjuvant CRT had significantly higher tumor-infiltrating T cell levels compared to all other response groups (TRG 2-5). These T cells were also in closer proximity to tumor cells in complete responders compared to other response groups. Notably, immune profiles of near-complete responders (TRG 2) showed more resemblance to non-responders (TRG 3-5) than to complete responders. A high CD8:CD163 ratio in the tumor was associated with an improved disease-free survival. Gene expression analyses revealed that T cells in non-responders were Th2-skewed, while complete responders were enriched in cytotoxic immune cells. Finally, complete responders were enriched in circulating memory T cells. preexisting immune activation enhances the chance for a complete pathological response to neoadjuvant CRT. This information can potentially be used for future patient selection, but also fuels the development of immunomodulatory strategies to enhance CRT efficacy.

Oncolytic adenovirus ORCA-010 increases the type 1 T cell stimulatory capacity of melanoma-conditioned dendritic cells.

Immune checkpoint blockade has resulted in durable responses in patients with metastatic melanoma, but only in a fraction of treated patients. For immune checkpoint inhibitors (ICI) to be effective, sufficient infiltration with tumor-reactive T cells is essential. Oncolytic viruses (OV) selectively replicate in and lyse tumor cells and so induce an immunogenic form of cell death, providing at once a source of tumor-associated (neo)antigens and of danger signals that together induce effective T cell immunity and tumor infiltration. Melanoma-associated suppression of dendritic cell (DC) differentiation effectively hampers OV- or immune checkpoint inhibitor (ICI)-induced anti-tumor immunity, due to a consequent inability to prime and attract anti-tumor effector T cells. Here, we set out to study the effect of ORCA-010, a clinical stage oncolytic adenovirus, on DC differentiation and functionality in the context of human melanoma. In melanoma and monocyte co-cultures, employing a panel of five melanoma cell lines with varying origins and oncogenic mutation status, we observed clear suppression of DC development with apparent skewing of monocyte differentiation to a more M2-macrophage-like state. We established the ability of ORCA-010 to productively infect and lyse the melanoma cells. Moreover, although ORCA-010 was unable to restore DC differentiation, it induced activation and an increased co-stimulatory capacity of monocyte-derived antigen-presenting cells. Their subsequent ability to prime effector T cells with a type I cytokine profile was significantly increased in an allogeneic mixed leukocyte reaction. Our findings suggest that ORCA-010 is a valuable immunotherapeutic agent for melanoma.

Efficacy of PD-1 blockade in cervical cancer is related to a CD8+FoxP3+CD25+ T-cell subset with operational effector functions despite high immune checkpoint levels.

BACKGROUND: Cervical cancer (CxCa) is mainly a locally invading disease that metastasizes to loco-regional lymph node basins before involving distant organs in more advanced stages. Local immune potentiation of tumor-draining lymph nodes (TDLN) may thus protect against tumor progression. METHODS: To identify therapeutic targets for local immune modulation, multi-parameter flow cytometric T-cell profiling of primary cervical tumors (PT) and TDLN (n = 37) was performed. The in-vitro effect of PD-1 blockade on T-cell reactivity to HPV16 E6 oncoproteins was determined in cultures of TDLN and PT single cell suspensions (n = 19). Also, intracellular cytokine staining (ICS) upon anti-CD3 stimulation was performed in metastatic TDLN (LN+) and PT (n = 7), as well as multiplexed immunofluorescence histochemistry staining (n = 8). RESULTS: Our data revealed elevated rates of activated regulatory T cells (aTregs) and of central or effector memory CD8+ T cells in metastatic TDLN (LN+) as compared to tumor-free TDLN (LN-), and equally high or even higher rates of these subsets in PT. Both memory subsets co-expressed multiple immune checkpoints. PD-1 blockade significantly enhanced detectable E6-specific T-cell responses in 4/5 HPV16+ LN+ and in 1/5 HPV16+ PT. Whereas aTreg rates were higher in anti-PD-1 non-responders, in responders elevated levels of CD8+FoxP3+CD25+ T cells were observed, which correlated with the efficacy of PD-1 blockade (P = 0.018). This subset was characterized by an early effector memory phenotype with particularly high levels of co-expressed PD-1, CTLA-4, TIM-3 and LAG-3 checkpoints, but, rather than exhausted, was shown upon polyclonal activation to produce higher levels of Granzyme-B and effector cytokines as compared to its CD8+FoxP3- counterparts. CONCLUSION: These observations support local PD-(L)1 blockade to interrupt loco-regional immune suppression in CxCa and control metastatic spread to TDLN. Furthermore, our data identify CD8+FoxP3+CD25+ T cells as therapeutic targets, which may also serve as predictive biomarker for PD-(L)1 checkpoint blockade.

Whole body PD-1 and PD-L1 positron emission tomography in patients with non-small-cell lung cancer.

PD-L1 immunohistochemistry correlates only moderately with patient survival and response to PD-(L)1 treatment. Heterogeneity of tumor PD-L1 expression might limit the predictive value of small biopsies. Here we show that tumor PD-L1 and PD-1 expression can be quantified non-invasively using PET-CT in patients with non-small-cell lung cancer. Whole body PD-(L)1 PET-CT reveals significant tumor tracer uptake heterogeneity both between patients, as well as within patients between different tumor lesions.

'DURVIT': a phase-I trial of single low-dose durvalumab (Medi4736) IntraTumourally injected in cervical cancer: safety, toxicity and effect on the primary tumour- and lymph node microenvironment.

BACKGROUND: Treatment with programmed cell death receptor (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors is a promising strategy to lift tumour-induced immune response suppression. However, the current systemic treatment often causes autoimmune side effects. In more than 50% of squamous cell cervical cancer, PD-L1 expression is detected. Moreover, we observed high and interrelated rates of PD-L1 positive macrophages and regulatory T cells in metastatic lymph nodes of cervical cancer patients. As cervical cancer in general initially metastasizes to regional lymph nodes, local administration of durvalumab (a PD-L1 checkpoint inhibitor) at an early stage will deliver these antibodies exactly where they are needed, facilitating immune protection. This may result in a clinical benefit while reducing undesirable side effects. METHODS: DURVIT is a non-randomized, single-arm, open-label, phase I study. Three escalating dose levels of intratumourally (i.t.) injected durvalumab will be tested, i.e. 5, 10 and 20 mg (three patients per dose level, with an additional three at the highest tolerated dose). The primary endpoint of this phase-I study is safety. Immune monitoring will consist of flow cytometric, immunohistochemical and functional T cell reactivity testing. The first patient has been included in this trial in November 2017. DISCUSSION: Evidence of safety and biological efficacy of this locally administered checkpoint blockade may expand adjuvant therapy options for cervical cancer patients. Early metastatic spread of cervical cancer cells may thus be controlled in the draining lymph node basin, and beyond, and hopefully delay or even prevent the onset of disease recurrence. TRIAL REGISTRATION: NTR6119 , 1-nov-2016.

Increased cytotoxic capacity of tumor antigen specific human T cells after in vitro stimulation with IL21 producing dendritic cells.

Monocyte derived dendritic cells (moDC) electroporated with tumor associated antigen derived mRNA can elicit specific T cells against tumor cells in vivo. IL21 has been shown to enhance activation and cytotoxicity in CD8+ T cells. We therefore investigated in vitro effects on human CD8+ T-cells after stimulation with IL21 mRNA electroporated moDC. Codon modification of the IL21 gene significantly enhanced IL21 production upon electroporation of moDC. Tumor associated antigen specific CTL induction efficiency was significantly enhanced when codon modified IL21 mRNA was co-electroporated with tumor associated antigen mRNA. Tumor associated antigen specific T cells induced by codon modified IL21-DC demonstrated increased cytotoxic capacity and killing compared to control cultures. In conclusion, ectopic expression of codon modified IL21 by moDC enhances the priming efficiency of the DC as well as the cytotoxic potential of the induced CTL.

Effector memory T-cell frequencies in relation to tumour stage, location and HPV status in HNSCC patients.

BACKGROUND: The immune system plays an important role in tumour immune surveillance. Head and neck squamous cell carcinoma patients are often immune compromised. OBJECTIVE: To chart the baseline levels of T-cell subpopulation frequencies in patients with cancer prior to treatment. SUBJECTS AND METHODS: Blood samples of patients were taken at the time of diagnosis, analysed with flowcytometry and compared with blood samples of healthy donors. RESULTS: Compared to healthy donors, a significant shift from naive to effector memory T cells was observed. This effect was most prominent in stage II patients. A similar shift from naive to effector memory T cells was noted in patients with oropharynx or larynx squamous cell carcinomas. Furthermore, the percentage of effector memory and effector T cells was higher in the group of patients with human papillomavirus-positive oropharyngeal squamous cell carcinomas, compared with patients with human papillomavirus-negative tumours, suggestive of virus-induced T-cell activation. CONCLUSION: Here, we provide a simple and easily implementable tool to document T lymphocyte subsets in the peripheral blood of head and neck cancer patients, which might be useful for prognosis and/or therapy response prediction.

The dermis as a portal for dendritic cell-targeted immunotherapy of cutaneous melanoma.

Complete surgical excision at an early stage remains the only curative treatment for cutaneous melanoma with few available adjuvant therapy options. Nevertheless, melanoma is a relatively immunogenic tumor type and particularly amenable to immunotherapeutic approaches. A dense network of cutaneous dendritic cells (DC) may account for the reported efficacy of vaccination through the skin and provide an attractive target for the immunotherapy of melanoma. Several phenotypically distinct DC subsets are discernable in the skin, among others, epidermal Langerhans cells and dermal DC. Upon appropriate activation both subsets can efficiently migrate to melanoma-draining lymph nodes (LN) to prime T cell-mediated responses. Unfortunately, from an early stage, melanoma development is characterized by strong immune suppression, facilitating unchecked tumor growth and spread. Particularly the primary tumor site and the first-line tumor-draining LN, the so-called sentinel LN, bear the brunt of this melanoma-induced immune suppression-and these are exactly the sites where anti-melanoma effector T cell responses should be primed by DC in order to prevent early metastasis. Through local immunopotentiation or through DC-targeted vaccination, the dermis may be utilized as a portal to activate DC and kick-start or boost effective T cell-mediated anti-melanoma immunity, even in the face of this immune suppression.

4-1BB-mediated expansion affords superior detection of in vivo primed effector memory CD8+ T cells from melanoma sentinel lymph nodes.

We have been studying the re-activation of tumor-associated antigen (TAA)-specific CD8(+) T cells in sentinel lymph nodes (SLN) of melanoma patients upon intradermal administration of the CpG-B oligodeoxynucleotide PF-3512676. To facilitate functional testing of T cells from small SLN samples, high-efficiency polyclonal T cell expansion is required. In this study, SLN cells were expanded via classic methodologies with plate- or bead-bound anti-CD3/CD28 antibodies and with the K562/CD32/4-1BBL artificial APC system (K32/4-1BBL aAPC) and analyzed for responsiveness to common recall or TAA-derived peptides. K32/4-1BBL-expanded T cell populations contained significantly more effector/memory CD8(+) T cells. Moreover, recall and melanoma antigen-specific CD8(+) T cells were more frequently detected in K32/4-1BBL-expanded samples as compared with anti-CD3/CD28-expanded samples. We conclude that K32/4-1BBL aAPC are superior to anti-CD3/CD28 antibodies for the expansion of in vivo-primed specific CD8(+) T cells and that their use facilitates the sensitive monitoring of functional anti-tumor T cell immunity in SLN.

Absence of Granzyme B positive tumour-infiltrating lymphocytes in primary melanoma excisional biopsies is strongly associated with the presence of sentinel lymph node metastasis.

BACKGROUND: Sentinel Lymph Node (SLN) status is strongly related to clinical outcome in melanoma patients. In this study we investigated the possible association between the presence of activated and/or suppressive Tumour Infiltrating Lymphocytes (TILs) and SLN status in clinically stage I/II melanoma patients. METHODS: Diagnostic primary melanoma samples from 20 patients with a sentinel lymph node metastasis were compared to melanoma samples from 20 patients with a negative sentinel lymph node, who were matched for gender, age and Breslow thickness. Presence of activated Granzyme B positive (GrB+) TILs, presence of suppressive (FoxP3+) TILs and MHC class I antigen expression on tumour cells were analysed by immunohistochemistry. RESULTS: FoxP3 and MHC-I expression had no direct bearing on the presence of melanoma metastases in the SLN. Whereas the presence of activated GrB+ TILs in the primary melanoma had no predictive value for SLN status either, their absence was strongly associated with the presence of metastasis in the SLN (p=0.001). While both GrB+ and FoxP3+ TILs could be detected in SLN metastases, a majority did not display MHC-I expression. CONCLUSION: These data support a role for cytotoxic T cells in the prevention of early metastasis of melanoma to the draining lymph nodes.

Defective differentiation of myeloid and plasmacytoid dendritic cells in advanced cancer patients is not normalized by tyrosine kinase inhibition of the vascular endothelial growth factor receptor.

Tumor-derived vascular endothelial growth factor (VEGF) has previously been identified as a causative factor in the disturbed differentiation of myeloid dendritic cells (DC) in advanced cancer patients. Here, we investigated the potential of vascular endothelial growth factor receptor (VEGFR) tyrosine kinase (TK) inhibition to overcome this defective DC differentiation. To this end, peripheral blood DC (PBDC) precursor and subset frequencies were measured in 13 patients with advanced cancer before and after treatment with AZD2171, a TK inhibitor (TKI) of VEGFR, coadministered with gefitinib, and an epidermal growth factor receptor (EGFR) TKI. Of note, not only myeloid DC but also plasmacytoid DC frequencies were significantly reduced in the blood of the cancer patients prior to treatment, as compared to healthy controls. Moreover, besides an accumulated population of immature myeloid cells (ImC), a population of myeloid suppressor cells (MSC) was significantly increased. Upon systemic VEGFR TK inhibition, DC frequencies did not increase, whereas the rate of circulating MSC showed a slight, but not significant, decrease. In conclusion, TK inhibition of VEGFR with AZD2171 does not restore the defective PBDC differentiation observed in advanced cancer patients.

Melanoma-specific tumor-infiltrating lymphocytes but not circulating melanoma-specific T cells may predict survival in resected advanced-stage melanoma patients.

PURPOSE: To study the effect of autologous tumor cell vaccinations on the presence and numbers of circulating CD8+ T cells specific for tumor-associated antigens (TAA) in metastatic melanoma patients. To investigate the correlation between the presence of tumor-infiltrating lymphocytes (TIL) and circulating TAA-specific CD8+ T cells before and after autologous tumor cell vaccination with overall survival. EXPERIMENTAL DESIGN: Twenty-five stage III and resected stage IV metastatic melanoma patients were adjuvantly treated with a series of intracutaneously injected autologous tumor cell vaccinations, of which the first two contained BCG as an immunostimulatory adjuvant. Tumor samples and blood samples obtained before and after vaccination of these patients were studied for the presence of TAA-specific T cells using HLA-tetramers and results were correlated with survival. RESULTS: In 5 of 17 (29%) melanoma patients, circulating TAA-specific T cells were detectable prior to immunizations. No significant changes in the frequency and specificity were found during the treatment period in all patients. Presence of circulating TAA-specific T cells was not correlated with survival (log rank, P=0.215). Inside melanoma tissue, TAA-specific TIL could be detected in 75% of 16 available tumor samples. In case of detectable TAA-specific TIL, median survival was 22.5 months compared to median survival of 4.5 months in case of absence of TAA-specific T cells (log rank, P=0.0094). In none of the patients, TAA-specific T cells were found both in tumor tissue and blood at the same time. CONCLUSIONS: These data suggest that the presence of TAA-specific TILs forms a prognostic factor, predicting improved survival in advanced-stage melanoma patients. The absence of TAA-specific T cells in the circulation suggests that homing of the tumor-specific T cell population to the tumor site contributes to the effectiveness of antitumor immunity.

CD40-targeted adenoviral GM-CSF gene transfer enhances and prolongs the maturation of human CML-derived dendritic cells upon cytokine deprivation.

Vaccination with autologous leukaemia-derived dendritic cells (DC) presents an adjuvant treatment option for chronic myeloid leukaemia (CML). Here, we show that high-efficiency CD40-targeted adenoviral gene transfer of GM-CSF to CML-derived DC induces long-lived maturation in the absence of exogenous cytokines and may thus ensure protracted stimulation of CML-specific T cells upon vaccination.

Extended neoadjuvant chemotherapy in locally advanced breast cancer combined with GM-CSF: effect on tumour-draining lymph node dendritic cells.

The effect of long-term administration of granulocyte-macrophage colony-stimulating factor (GM-CSF) on dendritic cell (DC) activation and survival in patients with locally advanced breast cancer (LABC) was studied. To this end, the number of activated DC (i.e. positive for the marker S100) in tumour-draining lymph nodes (TDLN) was determined and compared between LABC patients receiving neoadjuvant chemotherapy with GM-CSF (n=52) or without GM-CSF (n=11), and a control group of chemonaïve breast cancer patients (n=10). A significantly higher mean percentage of S100+ DC in the TDLN of the GM-CSF-treated patients (9.9%) was found compared with each of the respective control groups (5.3 and 5.1%, P=0.002). Moreover, intrapatient comparison before and after treatment showed that the percentage of S100+ DC significantly increased over the course of the GM-CSF treatment (P=0.018). In a univariate survival analysis with a median follow-up of 64 months, relatively high percentages of S100+ DC (> or =8%) were associated with a longer disease-free survival (DFS) (P=0.078). In patients with a high tumour load, where immunosuppressed conditions generally prevail, long-term administration of GM-CSF may thus contribute to survival through enhanced DC activation and consequently improved chances of effective antitumour immunity.

Biological concepts of prolonged neoadjuvant treatment plus GM-CSF in locally advanced tumors.

Local treatment with surgery and radiotherapy gives unsatisfactory results in patients with locally advanced cancer. In many cases distant metastases appear shortly after the removal of the primary tumor. Selecting breast cancer as a model for locally advanced disease, we are extrapolating our findings to other solid tumors. Neoadjuvant chemotherapy has improved survival of these patients by downstaging the primary tumors allowing local treatment and early elimination of distant micrometastases. We recently reported in this journal on a study of 42 patients with locally advanced breast cancer (LABC) who received prolonged neoadjuvant chemotherapy of doxorubicin, cyclophosphamide, and GM-CSF prior to surgery and postoperative radiotherapy. These results were promising and prompted us to initiate an international randomized phase III study in which either six neoadjuvant cycles or three neoadjuvant cycles plus three adjuvant cycles are being compared. In LABC patients treated with six neoadjuvant chemoimmunotherapy cycles, we observed a significant rise in the dendritic cell content of the axillary tumor-draining lymph nodes after therapy, associated with an encouraging disease free survival and overall survival. We hypothesize that the prolonged presence of draining lymph nodes in combination with the repeated tumor antigen release, dendritic cell recruitment, and activation may account for the observed increased survival of LABC patients. Based on our findings and the results of preclinical studies, we hypothesize that it is more effective to administer chemotherapy in an extended neoadjuvant regimen, taking advantage of the concurrent biological and immunological processes in the primary tumor and its draining lymph nodes.

Human papillomavirus type 16 E6/E7-specific cytotoxic T lymphocytes in women with cervical neoplasia.

Infection with oncogenic human papillomavirus (HPV) types is associated with the development of cervical neoplasia (CIN). The E6 and E7 oncoproteins are constitutively expressed in these lesions and are therefore putative targets for the immune response against HPV. The relation between HPV 16-specific memory cytotoxic T-cell precursor (mCTLp) activity to both oncoproteins and the natural course of cervical dysplasia was analyzed in 38 patients participating in a nonintervention cohort study of women with CIN and 11 HPV 16-positive cervical carcinoma patients. In a cross-sectional study at the end of follow-up prior to biopsy, 8 of 20 patients with a persistent HPV 16 infection had specific mCTLp against at least one of the two oncoproteins. By contrast, no specific mCTLp activity was detected in 11 HPV-negative patients or in 7 patients who had cleared an HPV 16 infection at the end of follow-up. However, 5 of 11 cervical carcinoma patients showed mCTLp activity against the E7 protein only. This study demonstrates that HPV 16 oncogene-specific mCTLp are present in women with HPV 16-positive CIN prior to any intervention. Since HPV-specific mCTLp were detected predominantly in women with high-grade lesions or invasive cervical carcinoma and not in women who cleared the virus, the role of naturally occurring mCTLp in the protection against HPV-associated cervical neoplasia remains to be established.