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This study was designed to screen for preliminary evidence of predictive markers of melanoma response to PD-1 blockade. We hypothesized that the following immune markers would be positive predictors of response: increased densities of CD103 + CD8 + T cells or Th1 lineage T-bet + T cells, high expression of CXCL9-11 and presence of tertiary lymphoid structures. Conversely, we hypothesized that the high expression of barrier molecules would be a negative predictor of response. Patients with advanced melanoma treated with pembrolizumab were identified, and clinical response as well as overall survival data were collected. Tumor samples were evaluated by multiplex immunofluorescence histology. All statistical analyses were performed in R Studio and Microsoft Excel using the Mann-Whitney U test, chi-square test, Spearman's rank correlation and Kaplan-Meier survival curves. Sixty-five advanced melanoma patients were identified, of whom 46 met inclusion criteria and were included in this study. Increased densities ( P = 0.04) and proportions ( P = 0.02) of CD8 + T cells expressing CD103 + were associated with complete response (CR) to pembrolizumab. Improved survival was associated with increased proportions of CD8 + cells expressing CD103 ( P = 0.0085) as well as decreased density of periplakin + cells ( P = 0.012) and periplakin + SOX10 + cells ( P = 0.0012). The density and proportion of CD8 + T cells expressing CD103 + positively correlated with PD-L1 expression, though PD-L1 expression was not significantly correlated with outcomes. This screening study found that increased density and proportion of CD8 + T cells expressing CD103 and decreased density of periplakin were associated with positive outcomes in patients with melanoma metastases treated with pembrolizumab and may warrant further study.

BackgroundTertiary lymphoid structures (TLS) are ectopic lymphoid organs that are localized near tumors and other sites of inflammation, and are commonly believed to support antitumor immunity. We previously published studies that show that most desmoplastic melanomas contain TLS, and that TLS in cutaneous metastatic melanomas varied widely in maturation state, in proportions of proliferating T and B cells, and in markers of B cell function, including AID and CD21. Thus, we hypothesized that there may be diversity in TLS function, or immunologic activity, among melanomas. To address this hypothesis, we evaluated TLS in primary desmoplastic melanomas (DM), and non-desmoplastic melanomas (non-DM) for markers of cell proliferation which are indicative of early immune activity.MethodsDM and non-DM tumor specimens, which included primary melanomas (PM), and cutaneous metastatic melanomas (CMM), were evaluated for TLS by multiplex Immunofluorescence histology, by staining for CD20, CD8, PNAd, Ki67, FoxP3, and DAPI. Lymphoid aggregates were identified in 20x spectrally unmixed images by visual inspection and identified as TLS if possessing organized T-cell and B-cell regions in addition to high endothelial venule-like vasculature (PNAd+). TLS were identified in 30 out of 64 screened (48%) CMM, 4/4 non-DM PM, and 8 out of 11 screened (73%) DM. Immune cells localized in TLS were enumerated using Halo software (Indica Labs). Mann-Whitney tests were used for statistical assessments.ResultsDM commonly contain a dense network of fibroblasts and associated stroma, which are not typical for other non-DM (PM and CMM). TLS in DM are located throughout the tumors, intratumorally, in sharp distinction from the peritumoral location of TLS in non-DM. Furthermore, when compared to TLS of non-DM (PM and CMM), TLS of DM contain increased densities of CD20+ B cells (PM p=0.007; CMM pConclusionsRecently published studies have identified tumor-associated fibroblasts as the likely initiating cells for TLS formation in murine melanomas. The intratumoral location of TLS in DM puts them in close proximity to the dense fibroblasts and desmoplastic stroma in these tumors, which may be responsible for their intratumoral location. The increased density of B and T cells, and higher proportion of proliferating (Ki67+) B cells, in DM than in non-DM, suggests that there may be greater immune activation, increased germinal center maturation, or less regulation in TLS of DM.Ethics ApprovalApproval was obtained for these studies under IRB protocol #’s 10598 and 19694.

Immune-cell infiltration is associated with improved survival in melanoma. Human melanoma metastases may be grouped into immunotypes representing patterns of immune-cell infiltration: A (sparse), B (perivascular cuffing), and C (diffuse). Immunotypes have not been defined for murine melanomas, but may provide opportunities to understand mechanism-driving immunotype differences. We performed immunohistochemistry with immune-cell enumeration, immunotyping, and vascular density scoring in genetically engineered (Braf/Pten and Braf/Pten/β-catenin) and transplantable (B16-F1, B16-OVA, and B16-AAD) murine melanomas. The transplantable tumors were grown in subcutaneous (s.c.) or intraperitoneal (i.p.) locations. Braf/Pten and Braf/Pten/β-catenin tumors had low immune-cell densities, defining them as Immunotype A, as did B16-F1 tumors. B16-OVA (s.c. and i.p.) and B16-AAD s.c. tumors were Immunotype B, while B16-AAD i.p. tumors were primarily Immunotype C. Interestingly, the i.p. location was characterized by higher immune-cell counts in B16-OVA tumors, with counts that trended higher for B16-F1 and B16-AAD. The i.p. location was also characterized by higher vascularity in B16-F1 and B16-AAD tumors. These findings demonstrate that spontaneously mutated neoantigens in B16 melanomas were insufficient to induce robust intratumoral immune-cell infiltrates, but instead were Immunotype A tumors. The addition of model neoantigens (OVA or AAD) to B16 enhanced infiltration, but this most often resulted in Immunotype B. We find that tumor location may be an important element in enabling Immunotype C tumors. In aggregate, these data suggest important roles both for the antigen type and for the tumor location in defining immunotypes.

BackgroundA vaccine containing 6 melanoma-associated peptides to stimulate helper T cells (6MHP) is safe, immunogenic, and clinically active. A phase I/II trial was designed to evaluate safety and immunogenicity of 6MHP vaccines plus programmed death 1 (PD-1) blockade.Participants and methodsParticipants with advanced melanoma received 6MHP vaccines in an incomplete Freund’s adjuvant (6 vaccines over 12 weeks). Pembrolizumab was administered intravenously every 3 weeks. Tumor biopsies at baseline and day 22 were analyzed by multiplex immunohistochemistry. Primary end points were safety (Common Terminology Criteria for Adverse Events V.4.03) and immunogenicity (ex vivo interferon-γ ELISpot assay). Additional end points included changes in the tumor microenvironment (TME) and clinical outcomes.ResultsTwenty-two eligible participants were treated: 6 naïve to PD-1 antibody (Ab) and 16 PD-1 Ab-experienced. Median follow-up was 24.4 months. Most common treatment-related adverse events (any grade) included injection site reactions, fatigue, anemia, lymphopenia, fever, elevated aspartate aminotransferase, pruritus, and rash. Treatment-related dose-limiting toxicities were observed in 3 (14%) participants, which did not cross the study safety bound. A high durable T cell response (Rsp) to 6MHP was detected in only one participant, but twofold T cell Rsps to 6MHP were detected in 7/22 (32%; 90% CI (16% to 52%)) by week 13. Objective clinical responses were observed in 23% (1 complete response, 4 partial responses), including 4/6 PD-1 Ab-naïve (67%) and 1/16 PD-1 Ab-experienced (6%). Overall survival (OS) was longer for PD-1 Ab-naïve than Ab-experienced participants (HR 6.3 (90% CI (2.1 to 28.7)). In landmark analyses at 13 weeks, OS was also longer for those with T cell Rsps (HR 6.5 (90% CI (2.1 to 29.2)) and for those with objective clinical responses. TME evaluation revealed increased densities of CD8+T cells, CD20+B cells, and Tbet+cells by day 22.ConclusionsTreatment with the 6MHP vaccine plus pembrolizumab was safe, increased intratumoral lymphocytes, and induced T cell Rsps associated with prolonged OS. The low T cell Rsp rate in PD-1 Ab-experienced participants corroborates prior murine studies that caution against delaying cancer vaccines until after PD-1 blockade. The promising objective response rate and OS in PD-1 Ab-naïve participants support consideration of a larger study in that setting.

Ipilimumab (IPI) can enhance immunity to the cancer-testis antigen NY-ESO-1. A clinical trial was designed to assess safety, immunogenicity, and clinical responses with IPI + NY-ESO-1 vaccines and effects on the tumor microenvironment (TME). Patients with measurable NY-ESO-1+ tumors were enrolled among three arms: A) IPI + NY-ESO-1 protein + poly-ICLC (pICLC) + incomplete Freund’s adjuvant (IFA); B) IPI + NY-ESO-1 overlapping long peptides (OLP) + pICLC + IFA; and C) IPI + NY-ESO-1 OLP + pICLC. Clinical responses were assessed by irRC. T cell and Ab responses were assessed by ex vivo IFN-gamma ELIspot and ELISA. Tumor biopsies pre- and post-treatment were evaluated for immune infiltrates. Eight patients were enrolled: 5, 2, and 1 in Arms A-C, respectively. There were no DLTs. Best clinical responses were SD (4) and PD (4). T-cell and antibody (Ab) responses to NY-ESO-1 were detected in 6 (75%) and 7 (88%) patients, respectively, and were associated with SD. The breadth of Ab responses was greater for patients with SD than PD (p = .036). For five patients evaluable in the TME, treatment was associated with increases in proliferating (Ki67+) CD8+ T cells and decreases in RORγt+ CD4+ T cells. T cell densities increased for those with SD. Detection of T cell responses to NY-ESO-1 ex vivo in most patients suggests that IPI may have enhanced those responses. Proliferating intratumoral CD8+ T cells increased after vaccination plus IPI suggesting favorable impact of IPI plus NY-ESO-1 vaccines on the TME. List of Abbreviations: Ab = antibody; CTCAE = NCI Common Terminology Criteria for Adverse Events; DHFR/DHRP = dihydrofolate reductase; DLT = Dose-limiting toxicity; ELISA = enzyme-linked immunosorbent assay; IFA = incomplete Freund’s adjuvant (Montanide ISA-51); IFNγ = Interferon gamma; IPI = Ipilimumab; irRC = immune-related response criteria; mIFH = multispectral immunofluorescence histology; OLP = NY-ESO-1 overlapping long peptides; PBMC = peripheral blood mononuclear cells; PD = Progressive disease; pICLC = poly-ICLC (Hiltonol), a TLR3/MDA-5 agonist; RLT = Regimen-limiting Toxicity; ROI = regions of interest; RT = room temperature; SAE = serious adverse event; SD = stable disease; TEAE = treatment-emergent adverse events; TLR = toll-like receptor; TME = tumor microenvironment; TRAE = treatment-related adverse events.

Desmoplastic melanomas (DM) have unique and challenging clinical presentations and histomorphology. A characteristic feature is the presence of scattered lymphoid aggregates. However, the nature of these aggregates is not defined. We hypothesized that they may be tertiary lymphoid structures (TLS), and may be associated with programmed death ligand 1 (PD-L1) expression. We searched our tissue database for 'pure' DMs and for scars as control tissues, collected clinical information, and reviewed H&E histology. We performed multispectral imaging after staining for CD8, CD20, PNAd, FoxP3, CD83, and Ki67, and assessed PD-L1 expression by immunohistochemistry. Pure DM samples were evaluable in 11 patients. All had desmoplastic stroma and lymphoid aggregates on H&E. The lymphoid aggregates of eight of the 11 (72%) DM samples and only three of the 11 scars contained features of TLS, defined as distinct clusters of B cells and CD8 T cells, CD83 dendritic cells in T-cell zones, and PNAd vasculature resembling high endothelial venules. PD-L1 was expressed by at least 1% of melanoma cells in six and by at least 5% of immune cells in 10 of the 11 DM samples. We found that most lymphoid aggregates in DM are organized, classical TLS. PD-L1 expression was detected in most cases and was highest in two cases of DM with TLS. However, low PD-L1 expression in some cases suggests that some DM cells may be unresponsive to interferon-γ. TLS support antigen presentation and T-cell responses in chronic inflammation and cancer. Their presence in DM likely reflects an adaptive immune response, which may be enhanced with immune therapies.

BackgroundIntratumoral (IT) cancer therapies may enhance T cell activation and tumor infiltration when combined with systemic checkpoint blockade. This approach may improve treatment of advanced breast cancer, which is commonly resistant to immune therapy.MethodsA multicenter basket-style trial (NCT02643303) was performed in patients with advanced solid tumors, who received polyICLC IT 1mg x 6, then intramuscular (IM) x 3, combined with intravenous (IV) durvalumab 1500 mg q4W. Most were assigned to cohorts also receiving tremelimumab: 10 mg IT or 75 mg IV. Goals were to assess tolerability and clinical activity. Treated tumors were evaluated for immune infiltrates on days (d) 0, 15, and 29 by multiparameter immunofluorescence histology. A strong signal for clinical response was in breast cancer patients; thus, an expansion cohort was enrolled. We report analysis of that breast cancer subgroup.ResultsNineteen participants with treatment-refractory recurrent breast cancer with median 4 prior lines of therapy were enrolled and treated with IV durvalumab and IT/IM polyICLC. Seventeen also received tremelimumab (15 IT, 2 IV). Common treatment-related AEs were fatigue, injection site pain, and chills. There was one dose-limiting toxicity in a participant who received tremelimumab IV, and died with severe hyponatremia (DLT) and progressive disease. Objective clinical responses (1 complete; 4 partial (1 unconfirmed)) were observed in 5 (26%), including 2/9 patients with triple-negative breast cancer (TNBC) and 3/10 with non-TNBC. Median OS was longer for those with CR, PR, or SD (not reached) vs. those with PD or not evaluable (5 months): two responders remain alive at 34+ and 40+ months. In injected tumors, there were significant increases from d0 to d29 in numbers/mm2 of CD8+ T cells, CD20+ B cells, mature dendritic cells (DC), macrophages, and CD56+ NK cells, and in CD8+ cells with antigen-experience (CD45RO), cytotoxic function (granzyme B), activation (ICOS1), or proliferation (Ki67). CD8+ cells expressing LAG3 and TIM3 increased, as did PDL1+ tumor cells and stromal cells. There were no differences in cells expressing IDO, ARG1, CD39, or CD73. Among patients with objective response, vs. all others, proportions of intratumoral CD8+ cells expressing Ki67 increased (p < 0.04).ConclusionsIT tremelimumab and polyICLC plus systemic durvalumab is safe and has clinical activity in patients with advanced TNBC and non-TNBC. The therapy enhances intratumoral immune effectors and markers of T cell function in hypothesis-generating data that warrant confirmatory studies. Clinical response was associated with longer survival and increased CD8 T cell proliferation.Trial RegistrationNCT02643303Ethics ApprovalThe study has been performed with approval of the institutional review boards of each participating institution (Roswell Park Cancer Institute: STUDY 00000121/I291016; Mount Sinai School of Medicine: IRB-17-01692; University of Virginia: IRB # 19276; Cleveland Clinic: 18-694; Toledo: 300176; Dartmouth: STUDY00031630; Emory: IRB00099445). All participants give informed consent before enrolling and participating. The study was also performed with approval from the FDA

BackgroundA multipeptide vaccine containing 6 melanoma-associated peptides to stimulate helper T cells (6MHP) is safe and immunogenic and has clinical activity. A phase I/II trial was designed to evaluate safety and immunogenicity of 6MHP vaccines plus PD1 blockade.MethodsParticipants with measurable advanced melanoma, age ≥ 18 years, and ECOG performance status 0–1 were administered 6MHP vaccine intradermally and subcutaneously in an incomplete Freund’s adjuvant on days (D) 1, 8, 15, 43, 64, and 85. Pembrolizumab 200 mg was administered intravenously every 3 weeks for up to two years. Biopsies of accessible tumors at baseline and D22 were analyzed by multiparameter immunofluorescence histology. Primary endpoints were safety (CTCAE 4.03) and immunogenicity (ex vivo IFNγ ELIspot assay). Secondary and exploratory endpoints included changes in the tumor microenvironment (TME), and clinical outcomes.ResultsTwenty-two eligible participants were enrolled and treated, including 6 naïve to PD-1 Ab and 16 anti-PD-1 Ab-experienced. Median follow-up was 20 months. Treatment-related adverse events (any grade) experienced by >20% were injection site reactions, fatigue, anemia, nausea, fever, bruising, and rash. Treatment-related dose limiting toxicities (grade 3 elevated AST, skin ulcer, or uveitis) were observed in 3 (14%), which did not cross the study safety bound. Objective clinical responses were observed in 23% (1 CR, 4 PR), including 4/6 anti-PD-1 Ab-naive (67%) and one 1/16 anti-PD1 Ab-experienced (6%). Four participants (18%) had SD as best radiographic response (18%), all in the Ab-experienced cohort. T cell responses to 6MHP were detected in seven participants (32%) by week 13 and were associated with clinical response (CR/PR 80% vs. SD/PD 18%; p = 0.01). Overall survival was prolonged for anti-PD-1 Ab naïve vs experienced (p = 0.0048), for those with T cell response (p = 0.045, landmark analysis after week 13), and for those with objective response (p = 0.0148). TME evaluation in 12 participants revealed significant increases by D22 in the densities (per mm2) of CD8+ T cells (p = 0.0186), CD20+ B cells (P = 0.002), and Tbet+ cells (p = 0.034).ConclusionsIn patients with advanced melanoma, combined treatment with the 6MHP vaccine plus pembrolizumab was safe, increased intratumoral T and B cells, as well as Th1 (Tbet+) cells, and induced T cell responses that were associated with objective response and with overall survival. The promising objective response rate and overall survival in patients naive to PD1 blockade supports consideration of a larger study to assess definitive benefit in that clinical setting.AcknowledgementsWe acknowledge the support of Merck for providing pembrolizumab at no charge, and the University of Virginia Cancer Center Support grant P30 CA044579 for support of shared resource facilities.Trial RegistrationThe clinical trial Mel64 (PATHVACS) is registered with Clinicaltrials.gov (NCT02515227).Ethics ApprovalThe clinical trial Mel64 (PATHVACS) was performed with IRB (#18174) and FDA approval (IND #10825) and is registered with Clinicaltrials.gov (NCT02515227). Written informed consent was obtained from each participant prior to participation in the study.

Optimal approaches to induce T cell infiltration of tumors are not known. Chemokines CXCL9, CXCL10, and CXCL11 support effector T cell recruitment and may be induced by IFN. This study tests the hypothesis that intratumoral administration of IFNγ will induce CXCL9-11 and will induce T cell recruitment and anti-tumor immune signatures in melanoma metastases.Nine eligible patients were immunized with a vaccine comprised of 12 class I MHC-restricted melanoma peptides and received IFNγ intratumorally. Effects on the tumor microenvironment were evaluated in sequential tumor biopsies. Adverse events (AEs) were recorded. T cell responses to vaccination were assessed in PBMC by IFNγ ELISPOT assay. Tumor biopsies were evaluated for immune cell infiltration, chemokine protein expression, and gene expression.Vaccination and intratumoral administration of IFNγ were well tolerated. Circulating T cell responses to vaccine were detected in six of nine patients. IFNγ increased production of chemokines CXCL10, CXCL11, and CCL5 in patient tumors. Neither vaccination alone, nor the addition of IFNγ promoted immune cell infiltration or induced anti-tumor immune gene signatures.The melanoma vaccine induced circulating T cell responses, but it failed to infiltrate metastases, thus highlighting the need for combination strategies to support T cell infiltration. A single intratumoral injection of IFNγ induced T cell-attracting chemokines; however, it also induced secondary immune regulation that may paradoxically limit immune infiltration and effector functions. Alternate dosing strategies or additional combinatorial treatments may be needed to promote trafficking and retention of tumor-reactive T cells in melanoma metastases.

Integrins α1β1 (CD49a), α2β1 (CD49b) and αEβ7 (CD103) mediate retention of lymphocytes in peripheral tissues, and their expression is upregulated on tumor infiltrating lymphocytes (TIL) compared to circulating lymphocytes. Little is known about what induces expression of these retention integrins (RI) nor whether RI define subsets in the tumor microenvironment (TME) with a specific phenotype. Human metastatic melanoma-derived CD8 TIL could be grouped into five subpopulations based on RI expression patterns: RI(neg), CD49a(+) only, CD49a(+)CD49b(+), CD49a(+)CD103(+), or positive for all three RI. A significantly larger fraction of the CD49a(+) only subpopulation expressed multiple effector cytokines, whereas CD49a(+)CD103(+) and CD49a(+)CD49b(+) cells expressed IFNγ only. RI(neg) and CD49a(+)CD49b(+)CD103(+) CD8 TIL subsets expressed significantly less effector cytokines overall. Interestingly, however, CD49a(+)CD49b(+)CD103(+) CD8 expressed lowest CD127, and highest levels of perforin and exhaustion markers PD-1 and Tim3, suggesting selective exhaustion rather than conversion to memory. To gain insight into RI expression induction, normal donor PBMC were cultured with T cell receptor (TCR) stimulation and/or cytokines. TCR stimulation alone induced two RI(+) cell populations: CD49a single positive and CD49a(+)CD49b(+) cells. TNFα and IL-2 each were capable of inducing these populations. Addition of TGFβ to TCR stimulation generated two additional populations; CD49a(+)CD49b(neg)CD103(+) and CD49a(+)CD49b(+)CD103(+.) Taken together, our findings identify opportunities to modulate RI expression in the TME by cytokine therapies and to generate subsets with a specific RI repertoire in the interest of augmenting immune therapies for cancer or for modulating other immune-related diseases such as autoimmune diseases.

BACKGROUND: One of the purported reasons of ineffectiveness of immunotherapy for GBM is the meager immune response in the tumor microenvironment. We have observed that GBM can harbor dense B-cell infiltrate, but their prevalence and function is unknown. Pre-clinical studies have shown that B-cells can act as antigen-presenting cells which can stimulate T-cell proliferation; however, B-cells can also downregulate effector T-cells by secreting immunosuppressive cytokines including IL-10. Our study aims to determine the roles of B-cells in GBM and their association with patient outcomes. METHODS: Multiplexed immunohistochemistry, imaging and quantitation was performed on primary GBM samples obtained between 1/2008-8/2015. Intratumoral CD20(+)B-cells and CD8(+)T-cells infiltrate were enumerated from 3 serial GBM sections. Relevant prognostic clinical and molecular variables were reviewed. We also analyzed the association of MS4A1 gene encoding B-cell antigen CD20 with survival from the TCGA. RESULTS: We observed an average infiltrate of 5.5 CD20(+) cells/mm(2)and 36.7 CD8(+)cells/mm(2)tumor. B-cells were stratified into CD20(low)(12 patients) and CD20(high)groups (36 patients) with 0.24 B-cells/mm(2) cut off. Kaplan-Meier analyses indicated that the CD20(low)group had better overall survival (OS) than the CD20(high)cohort (31.7 versus 18.7 months; p=0.02), while a trend toward improved survival was observed with high CD8(+)T-cell infiltration (p=0.06). Cox proportional hazard demonstrated an association between decreased OS and CD20(high)cohort (HR=2.8, p=0.03), but no significance seen between CD8(+)infiltration and OS (p=0.16). A positive correlation was detected between CD8(+)and CD20(+)density (p CONCLUSIONS: Our results suggest that B-cell infiltrate carries an inverse correlation with survival. We hypothesize that CD20(+)B-cells may be regulatory B-cells, limiting immune activation in GBM. Further studies are underway to understand the role of B-cells in the GBM microenvironment.

Clinical approaches to treat advanced melanoma include immune therapies, whose benefits depend on tumor-reactive T-cell infiltration of metastases. However, most tumors lack significant immune infiltration prior to therapy. Selected chemokines promote T-cell migration into tumors; thus, agents that induce these chemokines in the tumor microenvironment (TME) may improve responses to systemic immune therapy. CXCL10 has been implicated as a critical chemokine supporting T-cell infiltration into the TME. Here, we show that toll-like receptor (TLR) agonists can induce chemokine production directly from melanoma cells when combined with IFNγ treatment. We find that TLR2 and TLR6 are widely expressed on human melanoma cells, and that TLR2/6 agonists (MALP-2 or FSL-1) synergize with interferon-gamma (IFNγ) to induce production of CXCL10 from melanoma cells. Furthermore, melanoma cells and immune cells from surgical specimens also respond to TLR2/6 agonists and IFNγ by upregulating CXCL10 production, compared to treatment with either agent alone. Collectively, these data identify a novel mechanism for inducing CXCL10 production directly from melanoma cells, with TLR2/6 agonists +IFNγ and raise the possibility that intratumoral administration of these agents may improve immune signatures in melanoma and have value in combination with other immune therapies, by supporting T-cell migration into melanoma metastases.

Infiltration of cancers by T cells is associated with improved patient survival and response to immune therapies; however, optimal approaches to induce T cell infiltration of tumors are not known. This study was designed to assess whether topical treatment of melanoma metastases with the TLR7 agonist imiquimod plus administration of a multipeptide cancer vaccine will improve immune cell infiltration of melanoma metastases.Eligible patients were immunized with a vaccine comprised of 12 melanoma peptides and a tetanus toxoid-derived helper peptide, and imiquimod was applied topically to metastatic tumors daily. Adverse events were recorded, and effects on the tumor microenvironment were evaluated from sequential tumor biopsies. T cell responses were assessed by IFNγ ELIspot assay and T cell tetramer staining. Patient tumors were evaluated for immune cell infiltration, cytokine and chemokine production, and gene expression.Four eligible patients were enrolled, and administration of imiquimod and vaccination were well tolerated. Circulating T cell responses to the vaccine was detected by ex vivo ELIspot assay in 3 of 4 patients. Treatment of metastases with imiquimod induced immune cell infiltration and favorable gene signatures in the patients with circulating T cell responses. This study supports further study of topical imiquimod combined with vaccines or other immune therapies for the treatment of melanoma.

3033Background: Melanoma metastases limit infiltration and function of antitumor T cells in part by immunosuppression with IDO1. INCB024360 (epacadostat) is an IDO1 inhibitor that normalizes serum ...

Methods to induce T cell responses to protein vaccines have not been optimized. The immunostimulant AS15 has been administered with the recombinant MAGE-A3 protein (recMAGE-A3) i.m. but not i.d. or s.c. This study tests hypotheses that the i.d./s.c. route is safe and will increase CD4(+) and CD8(+) T cell responses to MAGE-A3.Twenty-five patients with resected stage IIB-IV MAGE-A3(+) melanoma were randomized to immunization with recMAGE-A3 combined with AS15 immunostimulant (MAGE-A3 immunotherapeutic) either i.m. (group A, n = 13) or i.d./s.c. (group B, n = 12). Adverse events were recorded. Ab responses to MAGE-A3 were measured by ELISA. T cell responses to overlapping MAGE-A3 peptides were assessed in PBMC and a sentinel immunized node (SIN) after 1 in vitro stimulation with recMAGE-A3, by IFN-γ ELISPOT assay and by flow cytometry for multifunctional (TNF-α/IFN-γ) responses.Both routes of immunization were well tolerated without treatment-related grade 3 adverse events. All patients had durable Ab responses. For all 25 patients, the T cell response rate by ELISPOT assay was 30 % in SIN (7/23) but only 4 % (1/25) in PBMC. By flow cytometry, multifunctional CD8(+) T cell responses were identified in one patient in each group; multifunctional CD4(+) T cell response rates for groups A and B, respectively, were 31 and 64 % in SIN and 31 and 50 % in PBMC.The MAGE-A3 immunotherapeutic was well tolerated after i.d./s.c. administration, with trends to higher CD4(+) T cell response rates than with i.m. administration. This study supports further study of AS15 by i.d./s.c. administration.

Purpose: A melanoma vaccine incorporating six peptides designed to induce helper T-cell responses to melanoma antigens has induced Th1-dominant CD4 + T-cell responses in most patients, and induced durable clinical responses or stable disease in 24% of evaluable patients. The present study tested whether this vaccine also induced antibody (Ab) responses to each peptide, and whether Ab responses were associated with T-cell responses and with clinical outcome. Experimental Design: Serum samples were studied from 35 patients with stage III-IV melanomas vaccinated with 6 melanoma helper peptides (6MHP). IgG Ab responses were measured by ELISA. Associations with immune response and overall survival were assessed by log-rank test and χ 2 analysis of Kaplan–Meier data. Results: Ab responses to 6MHP were detected by week 7 in 77% of patients, and increased to peak 6 weeks after the last vaccine and persisted to 6 months. Ab responses were induced most frequently to longer peptides. Of those with T-cell responses, 82% had early Ab responses. Survival was improved for patients with early Ab response ( P = 0.0011) or with early T-cell response ( P P = 0.0002). Conclusions: Vaccination with helper peptides induced both Ab responses and T-cell responses, associated with favorable clinical outcome. Such immune responses may predict favorable clinical outcome to guide combination immunotherapy. Further studies are warranted to understand mechanisms of interaction of these Abs, T-cell responses, and tumor control. Clin Cancer Res; 21(17); 3879–87. ©2015 AACR .

Meeting abstracts Intralesional therapies offer promise to modulate immune signatures within melanoma and other cancers, either as monotherapy or as a component of combination immune therapy. We have shown that the TLR2/6 agonists (MALP-2 and FSL-1) and IFNγ induce human melanoma cells to

T cell infiltration in the tumor microenvironment (TME) is positively correlated with survival. Infiltration is not a stable state, but a dynamic process of homing, infiltration, retention and survival. Every step in this process is crucial for the eventual tumor reactive activity of T cells. Our laboratory has previously shown a marked upregulation of retention integrins (RI) CD49a, CD49b and CD103 on tumor infiltrating lymphocytes (TIL) in melanoma. T cells in peripheral tissues expressing RI appear to have a cytotoxic phenotype and RI+ TIL are associated with improved patient survival. Despite their importance in retention of tumor reactive TILs, little is known about pathways inducing RI expression, except that TGFβ induces CD103. We hypothesized that other cytokines, TLR agonists and T cell receptor (TCR) stimulation can induce RI expression by circulating T cells. PBMCs were grown in presence of cytokines after TCR stimulation and RI expression was evaluated by flow cytometry after 2-7 days. Both CD103 and CD49a are induced by TGFβ, most strikingly on activated T cells. IL2 and IL10 also influence CD49a expression. CD49b expression is increased by IL2, IL4 and IL10, although this depends on T cell subset and activation state. TLR2, TLR6 and TLR7 agonists appear to induce CD49a and CD49b as well. In addition we have found that IL2 and TGFβ upregulate RI expression on T cells with different proliferation rates and cytotoxic activity. In conclusion, above results support our hypothesis by showing that RI expression is tightly regulated by cytokine and TCR stimulation. Interestingly, the regulating factors have different effects among the RI and phenotype of RI+ T cells. Which suggests a different role for each of the RI and a substantial contribution of the induction route in the determination of this role. Furthermore the cytokines found to be involved with RI expression are associated with either Th1, Th2 or Treg cells. All raising interesting questions about the features of the TME that best support tumor reactive T cell retention in the tumor.

Melanoma is currently the most lethal form of skin cancer. Clinical efforts to combat melanoma have included approaches to induce the immune system, through T-cell directed therapies, to clear melanoma. These approaches require that immune cells enter the tumor microenvironment to be clinically beneficial. However, most tumors lack significant immune infiltration prior to immune therapy, and immune therapies are hindered by a persistent lack of immune cell infiltration. Chemokines can promote T-cell migration into tumors; therefore agents that induce chemokine production by melanoma cells to promote T-cell infiltration may be clinically beneficial, and could potentially work synergistically with current immune treatments for melanoma. We hypothesized that TLR ligation of melanoma would induce immune cell attracting chemokine secretion directly from melanoma cells, alone or in combination with IFNγ. To test this hypothesis, we treated human melanoma cell lines (VMM1, DM13, DM93 and DM122) individually with TLR agonists and analyzed effects on the expression of chemokines CCL2-5, CXCL9-10, and CXCL12 by flow cytometric analysis. The following TLR agonists were tested: MALP-2 and FSL-1 (TLR2/6), poly-ICLC (TLR3), LPS (TLR4), CpG (TLR9), Resiquimod (TLR7/8), Imiquimod (TLR7). Our studies found that melanoma express TLRs 2, 3, 4, 6, 7, and 9, but that without exogenous stimulation, melanoma cells produce few immune cell attracting chemokines. Furthermore, stimulation of melanoma with the TLR agonists alone induced little chemokine production. However, TLR2/6 treatment of melanoma cells (MALP-2 or FSL-1) given in combination with IFNγ resulted in significant increases in CXCL10 and CCL3 chemokine production by melanoma. We found that TLR2 and TLR6 are widely expressed on human melanoma cells. Furthermore, stimulation of fresh patient melanoma specimens with TLR2/6 agonists plus IFNγ induces CXCL10 production from melanoma cells, endothelial cells and, to a lesser extent, several immune cell subsets including dendritic, monocytic, macrophage, and B-cell. Finally, ex vivo migration assays demonstrated that stimulation of melanoma cells with TLR2/6 agonists plus IFNγ increases CD4+ and CD8+ T-cell migration toward melanoma cells. CXCL10 has been implicated as a critical chemokine supporting T-cell infiltration into the tumor microenvironment. Collectively, these data identify TLR2/6 agonists and IFNγ as key inducers of CXCL10 production by melanoma cells and suggest that for tumors lacking immune cell infiltrates, systemic immune therapies may be improved by combination with intralesional therapy using TLR2/6 agonists plus IFNγ.

A major obstacle to cancer rejection is the failure of T cells to infiltrate and function within the tumor microenvironment (TME). Direct modulation of the TME to promote T cell homing and activation may enhance tumor control. Two pilot clinical trials were conducted to test the hypotheses that either intratumoral interferon-gamma (IFN-γ, Trial A, NCT00977145), or application of a TLR7 agonist, imiquimod (Trial B, NCT01264731) would induce favorable immune signatures and infiltration of CD8+ T cells into the TME.