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High-dose interleukin-2 (HD IL-2) has curative potential in metastatic melanoma (MM) and renal cell carcinoma (RCC). Radiotherapy (RT) kills cancer cells and induces immunomodulatory effects. Prospective trials exploring clinical and immunological properties of combined RT/HD IL-2 are still needed. We designed a phase II, single-arm clinical trial for patients with MM and RCC. The treatment schedule consisted of 3 daily doses of 6-12 Gy of RT to 1-5 non-index metastatic fields, before IL-2 at the first and third treatment cycle. HD IL-2 was administered by continuous infusion for 72 hours and repeated every 3 weeks for up to 4 cycles, thereafter every 4 weeks for a maximum of 2 cycles. The primary endpoint was the immunological efficacy of the combined RT/HD IL-2 treatment (assessed by IFN-γ ELISPOT). Nineteen out of 22 patients were evaluable for immunological and clinical response. Partial response occurred in 3 (15.7%) patients and stable disease was observed in 7 (36.8%). The disease control rate was 52.6% after a median follow up of 39.2 months. According to Common Terminology Criteria for Adverse Events 4.0 (CTCAE 4.0), the majority of toxicities were grade 1-2. Immunological responses were frequent and detected in 16 (84.2%) patients. Increased levels of IL-8 and IL-10 in melanoma, circulating effector memory CD4+ and intratumoral CD8+ T cells in both tumor types were detected after therapy. Overall the treatment was well tolerated and immunologically active. Immunomonitoring and correlative data on tumor and peripheral blood cell subsets suggest that this combination treatment could be a promising strategy for patients progressing after standard treatments.

For many years, oncological clinical trials have taken advantage of dendritic cells (DC) for the design of DC-based cellular therapies. This has required the design of suitable quality control assays to evaluate the potency of these products. The purpose of our work was to develop and validate a novel bioassay that uses flow cytometry as a read-out measurement. In this method, CD3+ cells are labeled with a fluorescent dye and the DC costimulatory activity is measured by the degree of T cell proliferation caused by the DC–T cell interaction. The validation of the method was achieved by the evaluation of essential analytical parameters defined by international guidelines. Our results demonstrated that the method could be considered specific, selective, and robust. The comparison between measured values and estimated true values confirmed a high level of accuracy and a lack of systematic error. Repeated experiments have shown the reproducibility of the assay and the proportionality between the potency and the DC amount has proven its linearity. Our results suggest that the method is compliant with the guidelines and could be adopted as a quality control assay or batch-release testing within GMP facilities.

Dendritic cell (DC)-based vaccination effectively induces anti-tumor immunity, although in the majority of cases this does not translate into a durable clinical response. However, DC vaccination is characterized by a robust safety profile, making this treatment a potential candidate for effective combination cancer immunotherapy. To explore this possibility, understanding changes occurring in the tumor microenvironment (TME) upon DC vaccination is required. In this line, quantitative and qualitative changes in tumor-infiltrating T lymphocytes (TILs) induced by vaccination with autologous tumor lysate/homogenate loaded DCs were investigated in a series of 16 patients with metastatic melanoma. Immunohistochemistry for CD4, CD8, Foxp3, Granzyme B (GZMB), PDL1, and HLA class I was performed in tumor biopsies collected before and after DC vaccination. The density of each marker was quantified by automated digital pathology analysis on whole slide images. Co-expression of markers defining functional phenotypes, i.e., Foxp3+ regulatory CD4+ T cells (Treg) and GZMB+ cytotoxic CD8+ T cells, was assessed with sequential immunohistochemistry. A significant increase of CD8+ TILs was found in post-vaccine biopsies of patients who were not previously treated with immune-modulating cytokines or Ipilimumab. Interestingly, along with a maintained tumoral HLA class I expression, after DC vaccination we observed a significant increase of PDL1+ tumor cells, which significantly correlated with intratumoral CD8+ T cell density. This observation might explain the lack of a significant concurrent cytotoxic reactivation of CD8+ T cell, as measured by the numbers of GZMB+ T cells. Altogether these findings indicate that DC vaccination exerts an important role in sustaining or de novo inducing a T cell inflamed TME. However, the strength of the intratumoral T cell activation detected in post-DC therapy lesions is lessened by an occurring phenomenon of adaptive immune resistance, yet the concomitant PDL1 up-regulation. Overall, this study sheds light on DC immunotherapy-induced TME changes, lending the rationale for the design of smarter immune-combination therapies.

Background Dendritic cells (DCs) are the most efficient antigen-presenting cells and act at the center of the immune system owing to their ability to control both immune tolerance and immunity. In cancer immunotherapy, DCs play a key role in the regulation of the immune response against tumors and can be generated ex vivo with different cytokine cocktails. Methods . We evaluated the feasibility of dinoprostone (PGE 2 ) replacement with the molecular analog sulprostone, in our good manufacturing practice (GMP) protocol for the generation of DC-based cancer vaccine. We characterized the phenotype and the function of DCs matured in the presence of sulprostone as a potential substitute of dinoprostone in the pro-inflammatory maturation cocktail consisting of tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β) and IL-6. Results . We found that sulprostone invariably reduces the recovery, but does not significantly modify the viability and the purity of DCs. The presence of sulprostone in the maturation cocktail increases the adhesion of single cells and of clusters of DCs to the flask, making them more similar to their immature counterpart in terms of adhesion and spreading proprieties. Moreover, we observed that sulprostone impairs the expression of co-stimulatory molecules and the spontaneous as well as the directed migration capacity of DCs. Discussion These findings underscore that the synthetic analog sulprostone strongly reduces the functional quality of DCs, thus cannot replace dinoprostone in the maturation cocktail of monocyte-derived DCs.

Although immunomodulating antibodies are highly effective in metastatic melanoma, their toxicity, related to the activation of T lymphocytes, can be severe. Anticancer vaccines promote a fairly specific response and are very well tolerated, but their effectiveness has yet to be demonstrated. We have been treating patients with advanced melanoma with an autologous dendritic cell vaccine since 2001; to better characterize the safety and efficacy of our product, we designed a retrospective study on all of our patients treated with the vaccine to date. We retrospectively reviewed both case report forms of patients included in clinical trials and medical records of those treated within a compassionate use program. Response was assessed according to the Response Evaluation Criteria In Solid Tumors criteria and toxicity has been graded according to CTCAE 4.0. Although the response rate has been rather low, the median overall survival of 11.4 months and the 1-year survival rate of 46.9% are encouraging, especially considering the fact that data were obtained in a heavily pretreated population and only about one quarter of the patients had received ipilimumab and/or BRAF inhibitors. Multivariate analysis confirmed that the development of an immune response was significantly correlated with a better prognosis (hazard ratio 0.54; P=0.019). The adverse events observed were generally mild and self-limiting. Our analysis confirms the excellent tolerability of our vaccine, making it a potential candidate for combination therapies. As efficacy seems largely restricted to immunoresponsive patients, future strategies should aim to increase the number of these patients.

Background High-dose interleukin-2 (HDIL-2) represents a curative treatment option in metastatic melanoma (MM) and renal cell carcinoma (RCC) patients, although still in need of improving its therapeutic efficacy. Radiotherapy (XRT) strongly synergizes with immunotherapy and may boost the effects of HDIL-2 allowing for less toxic schedules. Methods In this proof-of-principle phase II study, biological markers of immunological response were considered as primary endpoints in previously treated MM and RCC patients. The treatment consisted of 3 daily doses of XRT (6-12 Gy) delivered to one lesion before the first and third IL-2 infusion (18 MIU/m2/day by IV infusion for 72 h), repeated every 3 weeks for a maximum of 6 cycles. In a first stage, 4 out of 7 enrolled patients showed an immunological response allowing the recruitment of a further 12 patients according to the minimax two-stage Simon design. The immunological efficacy of the combined XRT/HDIL-2 treatment was assessed measuring the proportion of circulating immune effectors specific for tumor antigens known to be expressed in MM and in RCC (i.e. Tyrosinase, gp100, Mart-1, 5T4, CAIX/G250, EGFR, survivin, MAGEA3 and NYESO1) by means of INF-γ Elispot assay. Moreover, the predictive value of pre-treatment serum biomarkers was also assessed. Results Since September 2012 a total of 19 patients have been enrolled (9 RCC and 10 MM patients of which 6 uveal, 2 mucosal and 2 cutaneous) with a median age of 55 years. Assessed clinical responses were 4 PR (3 RCC and 1 MM), 6 SD (2 RCC and 4 MM) and 9 PD. Median PFS was 3.2 and 2.9 months and median OS was 8.7 and 6.7 months, for RCC and MM respectively. According to CTCAE 4.0, the majority of toxicities was grade 1-2. IL-2 dose was never reduced, nor was the infusion interrupted. Interestingly, we found an enhancement greater than 10% of antigen-specific spot-forming cells (SFCs) for at least one tumor antigen after treatment in 16 out of 19 patients. Moreover, we detected much lower serum basal levels of IL-8 and IL-1b in responders (CR/PR/SD=10) compared to non responders (PD = 9). Conclusion HDIL2/XRT combined treatment is well tolerated and fairly active in the MM and RCC settings. Clinical trial identification EudraCT: 2012-001786-32. Legal entity responsible for the study The authors. Funding Italian Ministry of Health as part of the “Ricerca Finalizzata 2009 - Direzione Generale della Ricerca Scientifica e Tecnologica” Call for Project Proposals. Disclosure All authors have declared no conflicts of interest.

IntroductionSurgery is one of the treatments of choice for patients with a single metastasis from melanoma but is rarely curative. Such patients could potentially benefit from consolidation immunotherapy. Vaccination with dendritic cells (DCs) loaded with tumour antigens elicits a tumour-specific immune response. In our experience, patients who developed delayed type hypersensitivity (DTH) after DC vaccination showed a median overall survival (OS) of 22.9 monthsvs4.8 months for DTH-negative cases. A phase II randomised trial showed an advantage OS of a DC vaccine over a tumour cell-based vaccine (2-year OS 72% vs31%, respectively). Given that there is no standard therapy after surgical resection of single metastases, we planned a study to compare vaccination with DCs pulsed with autologous tumour lysate versus follow-up.Methods and analysisThis is a randomised phase II trial in patients with resected stage III/IV melanoma. Assuming a median relapse-free survival (RFS) of 7.0 months for the standard group and 11.7 months for the experimental arm (HR 0.60), with a two-sided tailed alpha of 0.10, 60 patients per arm must be recruited. An interim futility analysis will be performed at 18 months. The DC vaccine, produced in accordance with Good Manufacturing Practice guidelines, consists of autologous DCs loaded with autologous tumour lysate and injected intradermally near lymph nodes. Vaccine doses will be administered every 4 weeks for six vaccinations and will be followed by 3 million unit /day of interleukin-2 for 5 days. Tumour restaging, blood sampling for immunological biomarkers and DTH testing will be performed every 12 weeks.Ethics and disseminationThe protocol, informed consent and accompanying material given to patients were submitted by the investigator to the Ethics Committee for review. The local Ethics Committee and the Italian Medicines Agency approved the protocol (EudraCT code no.2014-005123-27). Results will be published in a peer-reviewed international scientific journal.Trial registration number2014-005123-27.

Dendritic cells (DCs) are unique specialized antigen-presenting cells capable of priming naive T cells and inducing antigen-specific cytotoxic T lymphocytes. This study presents an update of clinical results from a DC-based phase I-II clinical vaccine trial in stage IV melanoma. From 2003 to 2010, 27 patients with metastatic melanoma were treated with mature DCs pulsed with autologous tumor lysate and keyhole limpet hemocyanin and with subcutaneous low-dose interleukin-2. Delayed-type hypersensitivity (DTH) tests for in-vivo immunomonitoring were performed at baseline and every four vaccinations thereafter. Two complete, two mixed and six partial responses, and five stable diseases were observed (overall response, 37.0%; clinical benefit, 55.5%). All 15 responders showed DTH positivity. A median overall survival of 22.9 months [95% confidence interval (CI): 13.4-61.3] for DTH-positive patients (19) and 4.8 months (95% CI: 3.9-11.9) for DTH-negative patients (8; log rank=7.26; P=0.007) was observed. The overall median overall survival was 16 months (95% CI: 9-33). Our results would seem to highlight a relationship between positive-DTH test and an improved survival.

Background Vaccination with dendritic cells (DC) loaded with tumor antigens elicits tumor-specific immune responses capable of killing cancer cells without inducing meaningful side-effects. Patients with advanced melanoma enrolled onto our phase II clinical studies have been treated with autologous DC loaded with autologous tumor lysate/homogenate matured with a cytokine cocktail, showing a clinical benefit (PR + SD) in 55.5% of evaluable cases to date. The beneficial effects of the vaccine were mainly restricted to patients who developed vaccine-specific immune response after treatment. However, immunological responses were only induced in about two-thirds of patients, and treatments aimed at improving immunological responsiveness to the vaccine are needed. Methods/Design This is a phase II, “proof-of-principle”, randomized, open-label trial of vaccination with autologous DC loaded with tumor lysate or homogenate in metastatic melanoma patients combined with immunomodulating RT and/or preleukapheresis IFN-α. All patients will receive four bi-weekly doses of the vaccine during the induction phase and monthly doses thereafter for up to a maximum of 14 vaccinations or until confirmed progression. Patients will be randomized to receive: (1.) three daily doses of 8 Gy up to 12 Gy radiotherapy delivered to one non-index metastatic field between vaccine doses 1 and 2 and, optionally, between doses 7 and 8, using IMRT-IMAT techniques; (2.) daily 3 MU subcutaneous IFN-α for 7 days before leukapheresis; (3.) both 1 and 2; (4.) neither 1 nor 2. At least six patients eligible for treatment will be enrolled per arm. Daily 3 MU IL-2 will be administered subcutaneously for 5 days starting from the second day after each vaccine dose. Serial DTH testing and blood sampling to evaluate treatment-induced immune response will be performed. Objective response will be evaluated according to immune-related response criteria (irRC). Discussion Based upon the emerging role of radiotherapy as an immunologic modifier, we designed a randomized phase II trial adding radiotherapy and/or preleukapheresis IFN-α to our DC vaccine in metastatic melanoma patients. Our aim was to find the best combination of complementary interventions to enhance anti-tumor response induced by DC vaccination, which could ultimately lead to better survival and milder toxicity.

3040 Background: Vaccination with dendritic cells (DC) is still a valid experimental option for metastatic melanoma (MM). However, only a few patients experience long-lasting objective responses and the majority of clinical responders afterwards relapse and die. Which mechanisms are actually responsible for this “secondary resistance” to whole tumor antigens-loaded DC vaccines is largely unknown. It has been hypothesized that suppressive immune cell subpopulations, regulatory T cells in particular, may progressively accumulate in tumor tissues thus hampering therapy-induced antitumor immune responses along time. To elucidate this issue we evaluated changes induced by immunologically effective DC vaccination in the composition of tumor-associated T cell subpopulations. Methods: 12 patients with MM previously enrolled in a phase I/II DC vaccine trial and for which tumor tissue taken before and after at least 4 induction vaccine doses were available, were included in the study. Intratumoral lymphocytes were evaluated by CD3, CD4, CD8, FoxP3 and GrB immunostainings, and quantified by a computer-assisted method. A nonparametric two-tailed Wilcoxon signed-rank test was utilized for evaluating differences in the distribution of the number of cell positive for each marker on the total cell counts in pre- and post-vaccine biopsies. Results: Our data showed a considerable and statistically significant decrease of intratumoral FoxP3+regulatory T cells in melanoma tissues after DC vaccination. In addition, the concurrent increase of intratumoral activated cytotoxic T lymphocytes, as shown by CD8 and Granzyme B stainings, indicated that this decrease has likely a functional relevance. Conclusions: Our findings that vaccination with DC loaded with autologous tumor lysate strongly reduces the intratumoral content of regulatory T cells add strength to the rationale for the development of potentially more effective combination schedules where whole tumor antigen-loaded DC vaccine prime and partially activate tumor-specific low-affinity T cells in a first tumor antigen-focusing step, followed by boosting with non-maximal doses of anti-CTLA-4 antibodies.

e14007 Background: Ashigh-dose Interleukin-2 (HDIL2) is a necessary component of a curative treatment strategy in melanoma and renal cell carcinoma (RCC), it is imperative to improve its therapeuti...

Background In cancer immunotherapy, dendritic cells (DCs) play a fundamental role in the dialog between innate and adaptive immune response, but several immunosuppressive mechanisms remain to be overcome. For example, a high number of CD4+CD25++Foxp3+ regulatory T-cells (Foxp3+Tregs) have been observed in the peripheral blood and tumor microenvironment of cancer patients. On the basis of this, we conducted a study on DC-based vaccination in advanced melanoma, adding low-dose temozolomide to obtain lymphodepletion. Methods Twenty-one patients were entered onto our vaccination protocol using autologous DCs pulsed with autologous tumor lysate and keyhole limpet hemocyanin. Patients received low-dose temozolomide before vaccination and 5 days of low-dose interleukin-2 (IL-2) after vaccination. Circulating Foxp3+Tregs were evaluated before and after temozolomide, and after IL-2. Results Among the 17 evaluable patients we observed 1 partial response (PR), 6 stable disease (SD) and 10 progressive disease (PD). The disease control rate (PR+SD = DCR) was 41% and median overall survival was 10 months. Temozolomide reduced circulating Foxp3+Treg cells in all patients. A statistically significant reduction of 60% was observed in Foxp3+Tregs after the first cycle, whereas the absolute lymphocyte count decreased by only 14%. Conversely, IL-2 increased Foxp3+Treg cell count by 75.4%. Of note the effect of this cytokine, albeit not statistically significant, on the DCR subgroup led to a further 33.8% reduction in Foxp3+Treg cells. Conclusions Our results suggest that the combined immunological therapy, at least as far as the DCR subgroup is concerned, effectively reduced the number of Foxp3+Treg cells, which exerted a blunting effect on the growth-stimulating effect of IL-2. However, this regimen, with its current modality, would not seem to be capable of improving clinical outcome.

8591 Background: One recently developed strategy in treating patients with stage IV melanoma consists of dendritic cell (DC) vaccination. This therapy has variable results, based on patients’ immun...

e13029 Background: Cytolytic T lymphocytes (CTL) able to kill tumor cells are efficiently induced by Dendritic Cells (DC); however, immunosuppressive factors, as CD4+CD25+FoxP3+ T lymphocytes (T-re...

We reviewed the clinical results of a dendritic cell-based phase II clinical vaccine trial in stage IV melanoma and analyzed a patient subgroup treated with standard therapies after stopping vaccination. From 2003 to 2009, 24 metastatic melanoma patients were treated with mature dendritic cells pulsed with autologous tumor lysate and keyhole limpet hemocyanin and low-dose interleukin-2. Overall response (OR) to vaccination was 37.5% with a clinical benefit of 54.1%. All 14 responders showed delayed type hypersensitivity positivity. Median overall survival (OS) was 15 months (95% CI, 8–33). Eleven patients underwent other treatments (3 surgery, 2 biotherapy, 2 radiotherapy, 2 chemotherapy, and 4 biochemotherapy) after stopping vaccination. Of these, 2 patients had a complete response and 5 a partial response, with an OR of 63.6%. Median OS was 34 months (range 16–61). Our results suggest that therapeutic DC vaccination could favor clinical response in patients after more than one line of therapy.

TPS311 Background: Dendritic cells (DCs) play a central role in the induction of specific antigen recognition and tumor cell killing. Therapeutic vaccination with DCs is based on the potential for the in vitro cultivation and maturation of DC precursors from peripheral blood over a maximum of 7 days using GM-CSF and IL-4 in order to avoid the influence of immunosuppressive mechanisms present in tumor tissue. Among these, attention has recently focused on CD4+CD25+FoxP3+ T lymphocytes (T-regs). It has been seen that daily low-dose temozolomide (TMZ) induces lymphopenia, with a consequent reduction in T-regs (Su YB, J Clin Oncol, 2004). Furthermore, in a preliminary experience, we evaluated the expression of tumor endothelial marker 8 (TEM8) as a predictive marker of immunological and clinical response in mature DCs (mDCs) (Venanzi FM, Cancer Immunol Immunother, 2009). Following our experience of a vaccination trial using autologous mDCs pulsed with autologous tumor lysate (ATL) and keyhole limpet hemocyani...

9042 Background: Dendritic cells (DCs) play a crucial role in the interplay between innate and adaptive immune response towards cancer. The combination of immunotherapies with standard treatments for cancer could represent a further chance for advanced melanoma patients. In the literature, higher response rates than those normally obtained have been reported after second-line chemotherapy in patients with non small cell lung cancer pre-treated with vaccines and in patients with follicular B-cell lymphoma vaccinated with an anti-idiotype vaccine whilst in remission. On the basis of this data, we reviewed and updated the clinical results of our dendritic cell based vaccine clinical trial in stage IV melanoma patients. Methods: From December 2002 to 2007, 24 pre-treated metastatic melanoma patients were vaccinated with mature DCs (mDCs) pulsed with autologous tumor lysate (ATL) and keyhole limpet hemocyanin (KLH) followed by a 5-day treatment with low-dose subcutaneous Interleukin-2. Results: We observed 2 complete response (CR), 2 mixed response (MR), 5 partial response (PR), 4 stable disease (SD) and 11 progressive disease (PD) (overall response (OS) 37.5%; clinical benefit 54.1%). All 13 responders had delayed-type hypersensitivity (DTH) positivity to KLH, of whom 10 also showed positivity to the lysate. Eleven (45.8%) of the 24 patients underwent further lines of treatment (5 chemotherapy [CT], 3 surgery [S], 4 biotherapy, 2 radiotherapy [RT] and 4 biochemotherapy [BioCT]) after stopping vaccination (8 due to progression and 3, in SD, because all of their lysate had been used). Of these 11 patients, 2 obtained CR (1 RT, 1 S), 5 PR (3 BioCT, 2 S) for an OR of 63.6%, 1 SD (BioCT) and 3 showed PD as the best response to subsequent therapies, with a median OS of 30 months (range 16–52). Of the 3 SD patients who were forced to stop vaccine treatment, 1 had CR following RT and 2 progressed. Conclusions: Metastatic melanoma responds poorly to standard therapy, in particular after first-line treatment. Vaccination could enhance clinical response to subsequent third- or fourth-line therapies, thus prolonging overall survival. No significant financial relationships to disclose.

Background Antigen processing by dendritic cells (DC) exposed to specific stimuli has been well characterized in biological studies. Nonetheless, the question of whether autologous whole tumor lysates (as used in clinical trials) are similarly processed by these cells has not yet been resolved. Methods In this study, we examined the transfer of peptides from whole tumor lysates to major histocompatibility complex class II molecules (MHC II) in mature dendritic cells (mDC) from a patient with advanced melanoma. Tumor antigenic peptides-MHC II proximity was revealed by Förster Resonance Energy Transfer (FRET) measurements, which effectively extends the application of fluorescence microscopy to the molecular level ( Results We detected significant energy transfer between donor and acceptor-labelled antibodies against HLA-DR at the membrane surface of mDC. FRET data indicated that fluorescent peptide-loaded MHC II molecules start to accumulate on mDC membranes at 16 hr from the maturation stimulus, steeply increasing at 22 hr with sustained higher FRET detected up to 46 hr. Conclusions The results obtained imply that the patient mDC correctly processed the tumor specific antigens and their display on the mDC surface may be effective for several days. These observations support the rationale for immunogenic efficacy of autologous tumor lysates.