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Background The efficacy of dendritic cell (DC) immunotherapy as a single therapeutic modality for the treatment of glioblastoma (GBM) patients remains limited. In this study, we evaluated in patients with GBM recurrence the immune-mediated effects of DC loaded with autologous tumor lysate combined with temozolomide (TMZ) or tetanus toxoid (TT). Methods In the phase I-II clinical study DENDR2, 12 patients were treated with 5 DC vaccinations combined with dose-dense TMZ. Subsequently, in eight patients, here defined as Variant (V)-DENDR2, the vaccine site was preconditioned with TT 24 hours before DC vaccination and TMZ was avoided. As a survival endpoint for these studies, we considered overall survival 9 months (OS9) after second surgery. Patients were analyzed for the generation of effector, memory, and T helper immune response. Results Four of 12 DENDR2 patients reached OS9, but all failed to show an immunological response. Five of eight V-DENDR2 patients (62%) reached OS9, and one patient is still alive (OS >30 months). A robust CD8+ T-cell activation and memory T-cell formation were observed in V-DENDR2 OS>9. Only in these patients, the vaccine-specific CD4+ T-cell activation (CD38+/HLA-DR+) was paralleled by an increase in TT-induced CD4+/CD38low/CD127high memory T cells. Only V-DENDR2 patients showed the formation of a nodule at the DC injection site infiltrated by CCL3-expressing CD4+ T cells. Conclusions TT preconditioning of the vaccine site and lack of TMZ could contribute to the efficacy of DC immunotherapy by inducing an effector response, memory, and helper T-cell generation.

Recently, we found that temozolomide (TMZ) can upregulate the expression of the multidrug-resistance protein ABCC3 in NK cells from both glioma-bearing mice and glioblastoma patients treated with dendritic cell immunotherapy combined with TMZ, allowing NK cells to escape apoptosis and favoring their role as antitumor effector cells. Here, we demonstrate that CD56dim NK cells expressing CD16+ are predominant in patients surviving more than 12 months after surgery without disease progression. CD56dim CD16+ NK cells co-expressed high levels of ABCC3 and IFN-γ. Notably, not only basal but also TMZ-induced ABCC3 expression was related to a strong, long-term NK cell response and a better prognosis of patients. The identification of the single nucleotide polymorphism (SNP) rs35467079 with the deletion of a cytosine (−897DelC) in the promoter region of the ABCC3 gene resulted associated with a better patient outcome. ABCC3 expression in patients carrying DelC compared to patients with reference haplotype was higher and modulated by TMZ. The transcription factor NRF2, involved in ABCC3 induction, was phosphorylated in CD56dim CD16+ NK cells expressing ABCC3 under TMZ treatment. Thus, ABCC3 protein and the SNP −897DelC can play a predictive role in patients affected by GBM, and possibly other cancers, treated with dendritic cell immunotherapy combined with chemotherapy.

In a two-stage phase II study, 24 patients with first diagnosis of glioblastoma (GBM) were treated with dendritic cell (DC) immunotherapy associated to standard radiochemotherapy with temozolomide (TMZ) followed by adjuvant TMZ. Three intradermal injections of mature DC loaded with autologous GBM lysate were administered before adjuvant TMZ, while 4 injections were performed during adjuvant TMZ. According to a two-stage Simon design, to proceed to the second stage progression-free survival (PFS) 12 months after surgery was expected in at least 8 cases enrolled in the first stage. Evidence of immune response and interaction with chemotherapy were investigated. After a median follow up of 17.4 months, 9 patients reached PFS12. In these patients (responders, 37.5%), DC vaccination induced a significant, persistent activation of NK cells, whose increased response was significantly associated with prolonged survival. CD8+ T cells underwent rapid expansion and priming but, after the first administration of adjuvant TMZ, failed to generate a memory status. Resistance to TMZ was associated with robust expression of the multidrug resistance protein ABCC3 in NK but not CD8+ T cells. The negative effect of TMZ on the formation of T cell-associated antitumor memory deserves consideration in future clinical trials including immunotherapy.

In a two-stage phase II study, 24 patients with first diagnosis of glioblastoma (GBM) were treated with dendritic cell (DC) immunotherapy associated to standard radiochemotherapy with temozolomide (TMZ) followed by adjuvant TMZ. Three intradermal injections of mature DC loaded with autologous GBM lysate were administered before adjuvant TMZ, while 4 injections were performed during adjuvant TMZ. According to a two-stage Simon design, to proceed to the second stage progression-free survival (PFS) 12 months after surgery was expected in at least 8 cases enrolled in the first stage. Evidence of immune response and interaction with chemotherapy were investigated. After a median follow up of 17.4 months, 9 patients reached PFS12. In these patients (responders, 37.5%), DC vaccination induced a significant, persistent activation of NK cells, whose increased response was significantly associated with prolonged survival. CD8+ T cells underwent rapid expansion and priming but, after the first administration of adjuvant TMZ, failed to generate a memory status. Resistance to TMZ was associated with robust expression of the multidrug resistance protein ABCC3 in NK but not CD8+ T cells. The negative effect of TMZ on the formation of T cell-associated antitumor memory deserves consideration in future clinical trials including immunotherapy.

BACKGROUND: Chemotherapy can influence the immune response by inducing immunogenic death of tumor cells or modulating tumor microenvironment (Galluzzi et al. 2012). The limitations of chemotherapy and immunotherapy as single therapeutic modalities have generated considerable interest in combinatorial strategies (Zitvogel L et al 2008). Here we focused on understanding the molecular mechanisms directly induced by temozolomide (TMZ), the standard chemotherapeutic agent for glioblastoma, that can activate immune cells. METHODS: We studied the in vivo effects of TMZ on immune cells by treating mice 9 days after intracranial implantation of GL261 gliomas with intraperitoneal injections of TMZ (5 mg/kg) or vehicle (control mice) for 5 days. Mice were sacrificed 20 hours after treatment on days 1 to 5: tumor and peripheral blood were harvested and analyzed by flow cytometry. RESULTS: Trafficking of NK1.1+ CD3- NK cells in blood, but not of CD8+ T cells, and their homing ability into the brain significantly increased in TMZ-treated mice on day 12 after the second administration of TMZ. At this early time point TMZ led to a significant enrichment of CD11b(low) CD27(high) and CD11b(high) CD27(high) subsets. Microarray analysis revealed differentially expressed genes represented in different clusters of which chemotaxis, cell cycle, multidrug resistance and anti-apoptosis were predominantly up-regulated in blood-derived NK cells isolated from TMZ-treated compared to control mice. We focused validation experiments on genes related to multidrug resistance and chemotaxis. Chemotaxis was assayed using the in vitro transwell system confirming that the migration ability of NK cells from treated mice significantly increased by 3-fold compared with controls. Increased expression of three ATP transporter genes was confirmed by real time PCR (2.6-fold higher than controls, P = 0.006). Five days after the end of the treatment we found an enrichment of CD11(high) CD27(low), the most potent effector subset of NK cells (Chiossone et al 2009). In agreement, IFN-gamma production evaluated by flow cytometry and the in vitro cytotoxic activity of NK cells from TMZ-treated mice were higher than that of NK cells from control mice. CONCLUSIONS: Our results support the idea that NK cells can be resistant to chemotherapy (Lowdell 2003; MacDonald HR et al 1995). In particular at early time points TMZ leads to an enrichment of NK cells with migratory function, in the later phase TMZ leads to an increase of NK cells promoting cytotoxic ability. SECONDARY CATEGORY: Preclinical Experimental Therapeutics.

2039Background: In the two stage phase I-II study DENDR-I, 24 patients with first diagnosis of glioblastoma (GBM) were treated with DC immunotherapy associated to standard radio-chemotherapy. To go...

A critical requirement of an efficient cancer immunotherapy is the generation of long-lasting, specific memory. In a clinical trial active at Istituto Besta, first diagnosis glioblastoma (GBM) patients, with post-surgery volume ≤10 cc, underwent leukapheresis before radiotherapy and chemotherapy with the alkylating agent temozolomide (TMZ). Three intradermal injections of mature dendritic cells (DCs) loaded by autologous tumor lysates were done before adjuvant chemotherapy. Subsequent 4 injections were performed in association with six cycles of adjuvant TMZ. Peripheral blood lymphocytes (PBLs) were analyzed by flow cytometry to characterize immune response before and after DC vaccines. The ratio of vaccination/baseline frequencies and counts (V/B ratio) of all of the immunological parameters for each patient was calculated, and the median of all of the observations used as the cut off value to separate patients. V/B ratio was correlated with the progression free survival (PFS) of each patient. Preliminary results from the interim analysis on 24 patients showed that an increased NK, but not CD8+ T cell response was significantly associated with prolonged survival (p In a group of responder patients (PFS>12), during the first three vaccines, CD8+ T cells underwent a rapid expansion and produced higher levels of IFN-γ compared to the baseline (p After the third vaccine and TMZ administration, primed CD8+ T cells failed to form an effector memory phenotype (CCR7negCD45RAnegCD62Llow/neg). Our results support a possible interference of adjuvant chemotherapy on effector memory formation. Further investigations are required to understand how memory T cells behave in response to repeated exposure to TMZ. Citation Format: Serena Pellegatta, Marica Eoli, Elena Anghileri, Sara Pessina, Carlo Antozzi, Simona Frigerio, Gabriele Cantini, Maria Grazia Bruzzone, Bianca Pollo, Eugenio A. Parati, Gaetano Finocchiaro. CD8+T cells fail to form an effector memory in glioblastoma patients treated with dendritic cell immunotherapy in combination with chemotherapy. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A031.

Dendritic cell (DC) immunotherapy is gaining momentum in clinical cancer immunotherapy. We set-up a phase I-II study in patients with first diagnosis of glioblastoma (GBM) in which DC immunotherapy was associated to standard radiochemotherapy. The primary goal was to evaluate progression free survival (PFS) 12 months after surgery (PFS-12) as defined by RANO criteria. Safety, feasibility and evidence of immune response were also considered. Twenty-four patients were assessed. After gross-total resection (

Abcc3, a member of the ATP-binding cassette transporter superfamily, plays a role in multidrug resistance. Here, we found that Abcc3 is highly expressed in blood-derived NK cells but not in CD8+ T cells. In GL261 glioma-bearing mice treated with the alkylating agent temozolomide (TMZ) for 5 d, an early increased frequency of NK cells was observed. We also found that Abcc3 is strongly upregulated and functionally active in NK cells from mice treated with TMZ compared to controls. We demonstrate that Abcc3 is critical for NK cell survival during TMZ administration; more importantly, Akt, involved in lymphocyte survival, is phosphorylated only in NK cells expressing Abcc3. The resistance of NK cells to chemotherapy was accompanied by increased migration and homing in the brain at early time points. Cytotoxicity, evaluated by IFNγ production and specific lytic activity against GL261 cells, increased peripherally in the later phases, after conclusion of TMZ treatment. Intra-tumor increase of the NK effector subset as well as in IFNγ, granzymes and perforin-1 expression, were found early and persisted over time, correlating with a profound modulation on glioma microenvironment induced by TMZ. Our findings reveal an important involvement of Abcc3 in NK cell resistance to chemotherapy and have important clinical implications for patients treated with chemo-immunotherapy.

Growing evidence suggests that chemotherapy can influence the immune response by inducing lymphopenia or enhancing immunogenicity of dying tumor cells. In a clinical trial currently active in our Institution, patients with first diagnosis of glioblastoma are treated with dendritic cells (DC) loaded with autologous tumor lysate together with standard radio and chemotherapy with temozolomide. Peripheral blood lymphocytes from 22 patients were analyzed by flow cytometry to identify immune cell activation before and after DC vaccines. The ratio of vaccine/baseline frequencies (V/B ratio) was correlated with the survival of each patient. Increased V/B ratio for NK cells was significantly associated with prolonged PFS and OS (median 15.0 vs 8.0 mo, p = 0.003; 22.0 vs 12.0 mo, p = 0.02, respectively). Using the murine malignant glioma GL261, we investigated the molecular mechanisms induced by TMZ on NK and CD8 T cells. We treated mice 9 days after intracranial implantation of GL261 cells with intraperitoneal injections of TMZ (5 mg/kg) or vehicle (control mice) for 5 days. Mice were sacrificed at different time points and tumor and peripheral blood harvested and analyzed by flow cytometry. Gene expression profiling on peripheral blood lymphocytes revealed an up-regulation of multidrug resistance genes in NK cells, but not in CD8 T lymphocytes, in TMZ-treated mice compared to controls. The increased expression of the ATP transporter gene Abcc3 was confirmed by real time PCR (4.2-fold higher than controls, P = 0.006). Using eFluxx-ID multidrug resistance (MDR) assay based on specific inhibitors, we also demonstrated that Abcc3 was functionally active during TMZ treatment. NK cell resistance to chemotherapy was accompanied by an increase in migration and homing ability into the brain at early time point and in cytotoxicity at later phases (beyond the end of TMZ treatment). Our data show that murine NK cells are resistant to and activated by TMZ chemotherapy. Further investigations in patients treated by radio-chemotherapy with or without DC immunotherapy are warranted. Note: This abstract was not presented at the meeting. Citation Format: Serena Pellegatta, Sara Pessina, Gabriele Cantini, Emanuela Cazzato, Dimos Kapetis, Gaetano Finocchiaro. Abcc3 up-regulation confers protection from chemotherapy to NK cells in a murine model of malignant glioma. [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 1343. doi:10.1158/1538-7445.AM2015-1343

Chemotherapy is currently regarded as a potential ally for cancer immunotherapy. Several anticancer agents, including classical chemotherapeutic compounds, are able to enforce tumor specific immune responses either by inducing the immunogenic death of tumor cells or by modulating key cells for immune suppression or activation. To determine whether Temozolomide (TMZ), the standard chemotherapeutic agent for glioblastoma and malignant gliomas, could induce tumor immunogenicity, we treated murine GL261 cells with 50 and 150 microM TMZ in vitro for 2, 8 and 20 hours. Flow cytometry showed that the NKG2D ligand, involved in NKG2D-mediated NK cell recognition of tumor cells, was highly expressed by TMZ-treated GL261, whereas GL261 treated with vehicle showed only a weak expression (P < 0.01). B7-H3, an inhibitory molecule for NK cells, significantly decreased in TMZ-treated GL261 cells (P < 0.01). TGF-beta1 and TGF-beta2 concentrations in the supernatant from GL261 treated with TMZ significantly decreased, as shown by ELISA (from 23.2 ± 2.5 and 478.4 ± 19.3 in vehicle to 13.2 ± 2.2 and 283.8 ± 25.9 in TMZ-treated cells, respectively, P < 0.0001). We therefore studied the effects of TMZ on anti-tumor NK cell response by treating mice 7 days after intracranial implantation of GL261 gliomas with intraperitoneal injections of TMZ (5mg/kg) or vehicle (control mice) for 5 days. Five mice were sacrificed 20 hours after treatment on days 1-5: brain, spleen and blood were harvested and analyzed by flow cytometry. Trafficking of NKp46+ NK1.1+ CD3- NK cells in blood but not in spleen and their homing ability into the brain significantly increased in TMZ-treated compared to control mice after the second administration of TMZ (7.5 ± 1.4 vs 2.3 ± 1.2, P = 0.001; 10.9 ± 0.4 vs. 3.9 ± 0.6, P = 0.005, respectively). Notably TMZ led to an enrichment of CD11bhigh CD27high NK cells, the most potent effector cells. To verify NK anti-glioma activity, NK1.1 positive cells were isolated from blood and brain of treated and control mice using magnetic separation and incubated with GL261 cells. NK cell cytotoxicity from TMZ-treated mice was significantly higher than that NK cells from control mice. These results support the contention that chemotherapy may induce enhancement of NK cell response and open new opportunities to design novel combined therapies reversing the immune suppressive role of glioblastoma and unmasking the therapeutic potential of NK responses. Citation Format: Serena Pellegatta, Gabriele Cantini, Sara Pessina, Gaetano Finocchiaro. NK cell activation and cytotoxicity can be enhanced with chemotherapy in a murine model of glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A60.

The glutamate-aspartate transporter GLAST is a radial glia marker that is highly expressed in GL261 stem-like cells (GSCs). To target GLAST, we treated glioma-bearing mice with three subcutaneous injections of four GLAST peptides emulsified with Montanide ISA-51 in association with granulocyte macrophage colony-stimulating factor (GM-CSF) injections. Vaccination with GLAST peptides significantly prolonged survival, effectively enhanced systemic T-cell and NK-cell responses and promoted robust antitumor cytotoxicity. GLAST expression significantly decreased in gliomas from immunized mice, as evaluated by histological analysis and real-time PCR (RT-PCR). Moreover, the immunization protocol led to the upregulation of interferonγ (IFNγ) and tumor necrosis factorα (TNFα) as well as to the downregulation of transforming growth factor (TGF) β1 and β2 in the tumor. Beyond these changes, gliomas from immunized mice exhibited an increased recruitment of NK cells and antigen-specific CD8+ T cells expressing the tumor homing molecule VLA-4, as well as a local chemotactic gradient featuring expression of CXCL10 (which may be responsible for the recruitment of CTLs), CCL3, CCL4 and CCL5 (which are involved in NK-cell migration), and NKG2D ligand on glioma cells. Importantly, although GLAST is expressed in the central nervous system, autoimmune reactions were not observed in immunized mice. Altogether, these results support the contention that GLAST may constitute a glioma antigen against which immune responses can be efficiently induced without major safety concerns.