mRNA based vaccines utilizing lipid-based delivery systems have been used for cancer therapy with some success targeting tumor associated antigens (TAA) or neoantigens. However, in many patients, T cell exhaustion or tumor suppression impedes the induction of a protective anti-tumor T cell response, which suggests that additional activation signals are required to reduce antagonistic tumor effects and reinvigorate the T cells. Here we sought to evaluate novel ionizable lipids for lipid nanoparticle (LNP)-formulations containing a tumor antigen mRNA as a therapeutic treatment for solid tumors and identify key immunogenic features of successful ionizable lipid candidates. Focusing on the induction of a tissue destructive immune response became the ideal in vivo screening to compare two novel ionizable lipids, INTENT-1 and INTENT-2. Both LNPs carrying the same mRNA encoded antigen induced good CD8+ T cell responses but only INTENT-2.1 LNP could cause tissue destruction. Mechanism of action studies revealed that INTENT-2.1 but not INTENT-1.1 LNP induced type I interferons, independently of the mRNA, to enhance anti-tissue CD8+ T cell responses. These results demonstrate efficacy of INTENT-2.1 LNP for cancer vaccines, shed light into its mechanism of action, and support its use in clinical trials to treat solid tumors.

5600 Background: PESCO, a phase 1/2 trial of Maveropepimut-S (MVP-S) in combination with Pembrolizumab and metronomic cyclophosphamide, showed safety and efficacy signals in metastatic ovarian cancer (OC). MVP-S uses the lipid-based DPX delivery platform to stimulate T cell immune response to survivin epitopes restricted by 5 HLA class I haplotypes (A1, A2, A3, A24, B7). Survivin is highly expressed in OC. We report exploratory correlative analysis including immune responses, HLA typing and molecular profiling. Methods: The study included a phase 1 dose escalation and expansion cohorts: A (platinum-sensitive high-grade serous [HGS]), B (platinum-resistant HGS), and C (rare OC histologies). Survivin-specific T-cell responses were assessed by flow cytometric detection of IFNγ following ex vivo PBMC re-stimulation with pooled survivin epitopes at on-treatment timepoints. A positive immune response was predefined as >0.1% IFNγ⁺ CD8⁺ T cells. HLA genotyping was mapped to MVP-S–restricted alleles. Molecular profiling was performed using next-generation sequencing (NGS) and/or whole-genome transcriptomic sequencing (WGTS). Results: Across 44 patients (pts), 37 (84%) carried ≥1 vaccine-relevant HLA allele and 23 (52%) carried ≥2. The most frequent alleles were A24 (16/44; 36%), A02 (15/44; 34%), A03 (12/44; 27%), B07 (11/44; 25%), and A01 (8/44; 18%). Survivin-specific immune responses were detected in 15/24 (62%) immune-evaluable pts and were strongly enriched among pts with clinical benefit: CR 1/1 (100%), PR 7/7 (100%), SD 6/10 (60%), versus PD 1/6 (16%); overall, 14/15 (93%) immune responders had clinical benefit. The longest survivin-specific response persisted for 195 weeks in a pt with MMR deficient tumor who had CR for 3 years. Exploratory HLA-outcome analysis suggested enrichment of A24 in pts with clinical benefit but absent in PD. NGS was performed in 44 pts and WGTS in 36. NGS identified at least one SNV/indel in 43/44 (97.7%) pts. In Phase 1 and Cohorts A/B (n=34, 68% HGS), TP53 was dominant (76.5%, 86% in HGS), followed by MYC (17.6%), NF1 (14.7%), and BRCA1/2 (each 8.8%). In Cohort C (n=10, 8 clear cell), ARID1A (70%) and PIK3CA (60%) were frequent. In platinum resistant pts (n=24), alterations included TP53 (67%), BRCA1/2 (21%), CCNE1(17%). Tumors with cell cycle/replication stress alterations were enriched among pts with PD (29% vs 8% in non-PD; P = 0.099) and immune non-responders (37.5% vs 6.7% in IFN responders; P = 0.103). Tumor mutation burden was low in all 26 pts tested. Conclusions: Survivin-specific immune responses were strongly enriched among pts with clinical benefit, supporting survivin as an active target in OC. HLA typing demonstrated broad coverage of MVP-S epitopes across pts. Molecular subtype may have influenced immune responses in this study. Our findings support biomarker-integrated studies to optimize immunotherapy combinations in OC. Clinical trial information: NCT03029403 .

This investigator-initiated, open-label phase 1/2 clinical trial evaluates maveropepimut-S, a survivin-targeting vaccine, combined with pembrolizumab and low-dose cyclophosphamide in patients with recurrent epithelial ovarian cancer (ClinicalTrials.gov identifier: NCT03029403). The primary endpoints are safety and clinical efficacy measured by overall response rate and disease control rate. Secondary endpoints include recommended phase 2 dose, progression-free survival, overall survival, and survivin-specific immune response. Forty-seven patients are enrolled and forty-four are evaluable. Most treatment-related adverse events are grade 1 or 2, most commonly injection site reactions. The recommended phase 2 dose is 0.25 milliliters. The overall response rate is 23% and the disease control rate is 67%, with greater activity in platinum-sensitive disease. Median progression-free survival is 6.3 months in platinum-sensitive disease and 1.2 months in platinum-resistant disease. Survivin-specific immune responses occur in 62.5% of tested patients and correlate with clinical benefit. The combination demonstrates tolerability and sustained clinical activity.

Abstract mRNA immunotherapies have gained interest for the treatment of tumors from various origins, however, their ability to provide long -term durable tumor control has been underwhelming. Here we report that novel mRNA lipid nanoparticle (LNP) vaccinations induce robust expansion of antigen-specific T cells, although this does not always correlate with their ability to infiltrate and kill solid tumors. Using a portfolio of novel ionizable lipids and a robust in vivo model that reliably identifies LNPs with prominent anti-tissue T cell activity we have identified a putative LNP candidate that provides long term tumor control in a murine syngeneic tumor model. We utilized the model antigen glycoprotein (Gp), from the lymphocytic choriomeningitis virus (LCMV), and produced mRNA encoding the immunodominant epitopes gp3333-41, gp6161-80 and gp276276-286 (3GP-mRNA). This mRNA was encapsulated in various novel LNP formulations and administered i.m. into naïve C57Bl/6 mice to track the induction of a robust CD8+ T cell response identified using tetramers to gp33 and gp276. Successful candidate LNPs were then tested in the RIPgp model of autoimmune diabetes. RIPgp transgenic mice express LCMV-Gp in the pancreatic β cells and offer a robust assay for the ability to induce antigen-specific T cells capable of breaking self-tolerance and infiltrating and killing target tissue. Utilizing the RIPgp model to screen LNP candidates we identified a lead candidate, C2-5A, that both induced a robust expansion of antigen-specific T cells and tissue destruction. When utilized in a colon adenocarcinoma model expressing the LCMV-Gp antigen (MC38-Gp), therapeutic dosing of LNP C2-5A as a monotherapy lead to long term tumor clearance in 40% of the treated animals. We believe this screening platform allows the selection of LNP candidates capable of breaking self-tolerance, and one such candidate C2-5A provides a potent vehicle and adjuvant for mRNA based cancer vaccines. Citation Format: Douglas G. Millar, Matthew J. Gold, Kirsten Olsen, Yu Wu, Yury Karpov, Robert Nechanitzky, Haritha Menon, Rajesh Krishnan, Robert Georgantas, Pamela Ohashi, Natalia Martin-Orozco. Next-generation LNPs induce effective anti-tumor T cell responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6740.

NK cells have been shown to exhibit inflammatory and immunoregulatory functions in a variety of healthy and diseased settings. In the context of chronic viral infection and cancer, distinct NK cell populations that inhibit adaptive immune responses have been observed. To understand how these cells arise and further characterize their immunosuppressive role, we examined in vitro conditions that could polarize human NK cells into an inhibitory subset. TGF-β1 has been shown to induce regulatory T cells in vitro and in vivo; we therefore investigated if TGF-β1 could also induce immunosuppressive NK-like cells. First, we found that TGF-β1/IL-15, but not IL-15 alone, induced CD103+CD49a+ NK-like cells from peripheral blood NK cells, which expressed markers previously associated with inhibitory CD56+ innate lymphoid cells, including high expression of GITR and CD101. Moreover, supernatant from ascites collected from patients with ovarian carcinoma also induced CD103+CD49a+ NK-like cells in vitro in a TGF-β-dependent manner. Interestingly, TGF-β1/IL-15-induced CD103+CD56+ NK-like cells suppressed autologous CD4+ T cells in vitro by reducing absolute number, proliferation, and expression of activation marker CD25. Collectively, these findings provide new insight into how NK cells may acquire an inhibitory phenotype in TGF-β1-rich environments.

Abstract Background: Maveropepimut-S (MVP-S) is a DPX-based immunotherapy that targets survivin-expressing tumor cells and induces a cytotoxic T cell response. Combination with Pembrolizumab (Pemb) and low-dose Cyclophosphamide (CPA) is expected to enhance immune response. This trial aims to evaluate the safety and efficacy of MVP-S, Pemb, and low-dose CPA in patients (pts) with recurrent epithelial ovarian cancer (EOC). Methods: Non-randomized, open-label, phase 1/2 study. Phase 1 escalation cohort used a 3+3 design and included platinum-resistant EOC treated at 2 MVP-S dose levels (DL). All doses were delivered subcutaneously. MVP-S DL1, elected as recommended phase 2 dose (RP2D), included a priming dose of 0.25mL followed by boosters of 0.25mL q6w. MVP-S was combined with CPA (50 mg BID every other week) and Pemb (200 mg q3w). Phase 2 comprised three expansion cohorts. Cohorts A and B allowed high-grade serous (HGSC) or endometrioid tumors sensitive and resistant to platinum, respectively. Exploratory Cohort C enrolled pts with rare EOC subtypes. The primary endpoint was overall response rate (ORR), with secondary endpoints of safety, PFS, and OS. Tumor response was assessed every 6 wks according to RECIST1.1. Activity signal in Cohort A was defined as at least 3/10 partial response (PR) or sustained (>12 wks) stable disease (SD), and for Cohort B as at least 2/10 PR or sustained SD. Biopsies and blood draws were performed before and on treatment for correlative analysis, including flow cytometry, genotyping and ctDNA. The survivin-specific immune response was detected by IFN-γ production after stimulation of PBMCs with survivin peptides. Results:16 pts in the phase 1 escalation cohort (10 DL1 and 6 DL2) and 31 in the phase 2 expansion cohorts (A:11, B:10, C:10) were enrolled. The median age was 60y (range 39-78), and the median prior therapy lines received was 3 (range 1-6). The median follow-up was 14.0 months. Most frequent histologies were HGSC (68%) and clear cell carcinoma (23%). 45 pts were evaluated for safety. The most common AE was injection site reaction, observed in 33 pts (14 G1; 12 G2; 7 G3). Other AEs included fatigue (n=20), anemia (n=18), and nausea (n=16). G1 and G2 accounted for 90% of all related AEs. G3/G4 immune-related AEs occurred in 3 and 1 pts, respectively. Among 44 pts evaluable for efficacy, 1 complete response,9 PR, and 16 SD were observed (ORR 23%). In cohort A, 4/10 pts had PR, and 5/10 had SD (4 of 5 for >12 wks). In cohort B, there was 1/10 PR and 3/10 sustained SD. Cohort C was composed predominantly of clear cell carcinoma, and 2/10 pts had PR, and 2/10 had SD as the best responses. Survivin peptide re-stimulation assays were conducted in 24 pts; survivin-specific immune responses were detected in 14 pts (58%) and correlated with clinical responses (PR/SD) in 13. Conclusion: Combination of MVP-S, low-dose CPA, and Pemb in EOC is well-tolerated and shows promising clinical activity. Primary efficacy endpoints were met in cohorts A and B. Survivin-specific immune responses were correlated with clinical outcomes. Citation Format: Ana C. Veneziani, Husam Alqaisi, Douglas G Millar, Ilaria Colombo, Eduardo Gonzalez-Ochoa, Swati Atale, Anthony Msan, Judy Quintos, Janelle Ramsahai, Vikas Garg, Pamela Soberanis, Neesha C Dhani, Robert C Grant, Lisa Wang, Valerie Bowering, Stephanie Lheureux, Pamela S Ohashi, Amit M Oza. Maveropepimut-S, a DPX-based immune-educating therapy, combined with Pembrolizumab and Cyclophosphamide in recurrent ovarian cancer, results from the Phase 1/2 PESCO Trial [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A074.

Supplementary figures and legends

Immunotherapeutic strategies aimed at enhancing tumor cell killing by tumor-specific T cells hold great potential for reducing tumor burden and prolonging survival of cancer patients. Although many potential tumor antigens have been described, identifying relevant targets when designing anti-cancer vaccines or targeted cell therapies remains a challenge. To identify novel, potentially immunogenic candidate tumor antigens, we performed integrated tumor transcriptomic, seromic, and proteomic analyses of high grade serous ovarian cancer (HGSC) patient tumor samples. We identified tumor neo-antigens and over-expressed antigens using whole exome and RNA sequencing and examined these in relation to patient-matched auto-antibody repertoires. Focusing on MHC class I epitopes recognized by CD8+ T cells, HLA-binding epitopes were identified or predicted from the highly expressed, mutated, or auto-antibody target antigen, or MHC-associated peptides (MAPs). Recognition of candidate antigenic peptides was assessed within the tumor-infiltrating T lymphocyte (TIL) population expanded from each patient. Known tumor-associated antigens (TAA) and cancer/testis antigens (CTA) were commonly found in the auto-antibody and MAP repertoires and CD8+ TILs recognizing epitopes from these antigens were detected, although neither expression level nor the presence of auto-antibodies correlated with TIL recognition. Auto-antibodies against tumor-mutated antigens were found in most patients, however, no TIL recognition of the highest predicted affinity neo-epitopes was detected. Using high expression level, auto-antibody recognition, and epitope prediction algorithms, we identified epitopes in 5 novel antigens (MOB1A, SOCS3, TUBB, PRKAR1A, CCDC6) recognized by HGSC patient TILs. Furthermore, selection of epitopes from the MAP repertoire identified 5 additional targets commonly recognized by multiple patient TILs. We find that the repertoire of TIL specificities includes recognition of highly expressed and immunogenic self-antigens that are processed and presented by tumors. These results indicate an ongoing autoimmune response against a range of self-antigens targeted by HGSC TILs.

Abstract High-grade serous ovarian cancer (HGSC), the principal cause of death from gynecologic malignancies in the world, has not significantly benefited from advances in cancer immunotherapy. Although HGSC infiltration by lymphocytes correlates with superior survival, the nature of antigens that can elicit anti-HGSC immune responses is unknown. The goal of this study was to establish the global landscape of HGSC tumor-specific antigens (TSA) using a mass spectrometry pipeline that interrogated all reading frames of all genomic regions. In 23 HGSC tumors, we identified 103 TSAs. Classic TSA discovery approaches focusing only on mutated exonic sequences would have uncovered only three of these TSAs. Other mutated TSAs resulted from out-of-frame exonic translation (n = 2) or from noncoding sequences (n = 7). One group of TSAs (n = 91) derived from aberrantly expressed unmutated genomic sequences, which were not expressed in normal tissues. These aberrantly expressed TSAs (aeTSA) originated primarily from nonexonic sequences, in particular intronic (29%) and intergenic (22%) sequences. Their expression was regulated at the transcriptional level by variations in gene copy number and DNA methylation. Although mutated TSAs were unique to individual tumors, aeTSAs were shared by a large proportion of HGSCs. Taking into account the frequency of aeTSA expression and HLA allele frequencies, we calculated that, in Caucasians, the median number of aeTSAs per tumor would be five. We conclude that, in view of their number and the fact that they are shared by many tumors, aeTSAs may be the most attractive targets for HGSC immunotherapy.

HLA-restricted T cell responses can induce antitumor effects in cancer patients. Previous human T cell research has largely focused on the few HLA alleles prevalent in a subset of ethnic groups. Here, using a panel of newly developed peptide-exchangeable peptide/HLA multimers and artificial antigen-presenting cells for 25 different class I alleles and greater than 800 peptides, we systematically and comprehensively mapped shared antigenic epitopes recognized by tumor-infiltrating T lymphocytes (TILs) from eight melanoma patients for all their class I alleles. We were able to determine the specificity, on average, of 12.2% of the TILs recognizing a mean of 3.1 shared antigen-derived epitopes across HLA-A, B, and C. Furthermore, we isolated a number of cognate T cell receptor genes with tumor reactivity. Our novel strategy allows for a more complete examination of the immune response and development of novel cancer immunotherapy not limited by HLA allele prevalence or tumor mutation burden.

Abstract HLA-restricted T cell responses toward immunogenic peptides, whether mutated or non-mutated, can induce antitumor responses in patients with advanced cancer. The fact that potential non-mutated antigens are greater in number than mutated antigens by multiple orders of magnitude and the high polymorphism of HLA genes may have hampered comprehensive analyses of the specificity of antitumor T cell responses toward non-mutated antigens than mutated antigens. Unlike shared antigens, the vast majority of neoantigens are not shared and are unique to each patient. The elucidation of T cell epitopes derived from shared antigens may facilitate the robust development of an efficacious and safe adoptive T cell therapy that is readily available to a larger cohort of cancer patients. It is well established that melanoma tumor-infiltrating T lymphocytes (TILs) contain antitumor T cells that are specific for both non-mutated and mutated antigens. The adoptive transfer of TILs can induce sustained clinical responses in some patients with advanced melanoma. However, a precise and extensive understanding of the shared antigen targets of TILs has been lacking. In this study, TILs were isolated from 8 metastatic melanoma patients, polyclonally expanded in vitro, and their shared antigen specificities for all 45 (25 different) class I alleles were examined. The combination of structure-based analysis using human cell-based peptide/HLA (pHLA) multimers and functional analysis using artificial antigen-presenting cells (APCs) were used to determine antigen-specific T cell responses. We were able to determine the specificity of 12.2 ± 7.2% (mean ± SD, max 25.8%, min 4.6%) of CD8+ T cells in an expanded TIL culture toward 3.0 ± 1.8 (mean ± SD, max 6, min 1) previously known or novel peptides derived from shared antigens. Furthermore, we isolated a number of cognate TCR genes with potent tumor reactivity from the CD8+ T cells. The strategy employed in this study using a library of paired human cell-based pHLA multimers and artificial APCs has enabled us to decipher the antigen specificity of tumor-specific T cells for any given HLA class I allele, regardless of allele frequency and for an infinite number of peptides. It has also allowed us to build a large database of class I-restricted peptides and cognate tumor-reactive TCR genes at an unprecedented scale. This database will be a valuable tool in defining the immune response at the level of each individual cancer patient with precision as well as the identification and validation of biomarkers to aid in patient-based selection of a cancer immunotherapy regimen. Furthermore, this database will help the robust development of novel cancer vaccines and TCR gene therapies for patients with a low mutation burden. Citation Format: Kenji Murata, Kayoko Saso, Linh T. Nguyen, Douglas Millar, Marcus O. Butler, Pamela S. Ohashi, Naoto Hirano. Decoding shared antigenic epitopes and their cognate TCR genes in melanoma TILs using a library of paired human cell-based pHLA multimers and artificial APCs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 568.

Benveniste et al. have uncovered γδ T cells that recognize peptide antigens in an MHC-restricted manner. γδ T cells come to the fore Studies on T cells within the tumor microenvironment (TME) have largely focused on T cells that express αβ T cell receptors (TCRs). Using an in vitro culture system to expand melanoma antigen–specific T cells, Benveniste et al. have identified γδ T cells that recognize melanoma antigens in a class I MHC–restricted manner. To understand how these T cells recognize antigens in an MHC-restricted fashion, they crystallized one of these γδ TCRs complexed with cognate peptide, MHC, and β2 microglobulin. Given the success of T cell–centric therapies in cancer, the results presented here call for a closer examination of the role of γδ T cells in the TME of melanomas and other cancers. Antigen recognition by T cells bearing αβ T cell receptors (TCRs) is restricted by major histocompatibility complex (MHC). However, how antigens are recognized by T cells bearing γδ TCRs remains unclear. Although γδ T cells can recognize nonclassical MHC, it is generally thought that recognition of antigens is not MHC restricted. Here, we took advantage of an in vitro system to generate antigen-specific human T cells and show that melanoma-associated antigens, MART-1 and gp100, can be recognized by γδ T cells in an MHC-restricted fashion. Cloning and transferring of MART-1–specific γδ TCRs restored the specific recognition of the initial antigen MHC/peptide reactivity and conferred antigen-specific functional responses. A crystal structure of a MART-1–specific γδ TCR, together with MHC/peptide, revealed distinctive but similar docking properties to those previously reported for αβ TCRs, recognizing MART-1 on HLA-A*0201. Our work shows that antigen-specific and MHC-restricted γδ T cells can be generated in vitro and that MART-1–specific γδ T cells can also be found and cloned from the naïve repertoire. These findings reveal that classical MHC-restricted human γδ TCRs exist in the periphery and have the potential to be used in developing of new TCR-based immunotherapeutic approaches.

Einleitung: Die Immuntherapie erscheint ein vielversprechender und neuer Therapieansatz für das hepatozelluäre Karzinom (HCC) zu sein. Die Identifikation spezifischer Tumorantigene stellt die Basis für die Entwicklung einer gezielten Immuntherapie dar. Bislang wurden jedoch nur sehr wenige HCC-spezifische Tumorantigene identifiziert. Fehlregulierte Signalwege kennzeichnen geradezu eine maligne entartete Zelle und fast alle Signalwege werden über Phosphorylierung gesteuert. Falsch und vermehrt phosphorylierte Signalproteine können über Human Leukozyte Antigen (HLA) Moleküle auf der Zelloberfläche maligne entarteter Zellen präsentiert und von T Zellen erkannt werden.

Thymic selection shapes the repertoire of potentially autoreactive thymocytes that are allowed to mature. The expression pattern of self antigen seen by thymocytes determines the number and functional ability of autoreactive T cells.

Despite the high incidence of HCC, being the fifth most common cancer worldwide, current therapeutic options remain limited for advanced HCC. There is, however, first evidence of clinical improvement after checkpoint blockade and it has also been shown that CD8+ T-cell responses targeting tumor antigens beneficially impact the survival of HCC patients. Immunotherapy therefore seems to be a promising approach for HCC treatment. The identification of tumor-specific antigens provides the basis for the development of an efficient targeted immunotherapy. Of note, until today only few tumor-specific antigens for HCC were identified. Promising proteins that harbor tumor antigens are so called phosphoproteins. This is because phosphoproteins are abundantly integrated in most signaling pathways and dysregulation of signaling pathways including aberrant and increased phosphorylation of proteins represents one hallmark of cancer. These emerging phosphoproteins can be degraded and the derived peptide fragments are presented via MHC-class I molecules on the cell surface of altered cells leading to T-cell recognition. We therefore claim that MHC-class I-associated phosphopeptides are attractive new tumor antigens for CD8+ T-cell-based immunotherapy of HCC.

TLR-induced maturation of dendritic cells (DCs) leads to the production of proinflammatory cytokines as well as the upregulation of various molecules involved in T cell activation. These are believed to be the critical events that account for the induction of the adaptive immune response. In this study, we have examined the role of miR-155 in DC function and the induction of immunity. Using a model in which the transfer of self-Ag–pulsed, TLR-matured DCs can induce a functional CD8 T cell response and autoimmunity, we find that DCs lacking miR-155 have an impaired ability to break immune tolerance. Importantly, transfer of self- Ag-pulsed DCs overexpressing miR-155 was sufficient to break tolerance in the absence of TLR stimuli. Although these unstimulated DCs induced T cell function in vivo, there was no evidence for the upregulation of costimulatory ligands or cytokine secretion. Further analysis showed that miR-155 influenced the level of the phosphatase SHIP1 in DCs and that the lack of SHIP1 in DCs was sufficient to break T cell tolerance in vivo, again in the absence of TLR-induced DC maturation. Our study demonstrates that the overexpression of miR-155 in DCs is a critical event that is alone sufficient to break self-tolerance and promote a CD8-mediated autoimmune response in vivo. This process is independent of the induction of conventional DC maturation markers, indicating that miR-155 regulation of SHIP represents a unique axis that regulates DC function in vivo.

A versatile approach is proposed for the synthesis of novel immunoactive nanomaterials based on biocompatible poly(glycerol monomethacrylate) (PGMMA). Propargyl-terminated PGMMA is synthesized via atom transfer radical polymerization and then modified through the introduction of dangling acrylate groups, at controlled degree of functionalisation. Acrylates are then able to react quantitatively with thiols, such as immunoactive thiomannose, through Michael-type addition under mild conditions and at a physiologically acceptable pH. The terminal propargyl group can be modified independently with azide end-capping groups and it is utilized to graft the macromolecules to a fluorescent dye. The resulting mannose-linked PGMMAs confirm a safe cytotoxic profile and are able to stimulate cytokine production (TNFα), membrane protein expression (CD40), and cellular uptake in bone marrow derived dendritic cells. Cell stimulation is dependent on the mannose content and enhanced by serum proteins, suggesting a role for mannose-binding receptors and/or complement receptors in the cell membrane.