Improved Tumor Immunity Research Articles

B2AR Deletion from T-Cells Enhances Tumor Immunity in a Tumor Metastasis Model

Abstract Previous studies suggest that Beta-2-adrenergic receptor (β2-AR) signaling plays a role in dampening anti-tumor immune response. Given that B2AR is expressed in innate and adaptive immune cells, , it remains to be determined how B2AR signaling affects the activity of specific types of immune cells in the setting of tumor immunity. Therefore, we have developed T cell-specific deletion of B2AR by crossing LCK-Cre mice with B2AR Floxed mice, and used the resultant T cell-specific B2AR knockout (LCRCre-B2ARFL) mice to study tumor metastasis. We utilized the B16-F10 melanoma model via intravenous injection and examined metastatic tumor nests in the lungs 2-3 weeks after tumor injection. Our findings indicate that (LCRCre-B2ARFL) mice showed significantly lower burden of metastatic tumor nests in the lungs compared to control groups (LCKCre mice and B2ARFL mice). These results indicate that endogenous B2AR signaling in T cells plays an immune checkpoint role, restraining their anti-tumor activity, while selective deletion of β2AR from T cells enhances their anti-tumor function, resulting in significant reduction of tumor metastasis. Therefore, this study provides an important rationale for blocking B2AR signaling to improve tumor immunity and disabling B2AR in adoptive T cell therapy for cancer patients.

Fibroblast activation protein-targeted near-infrared photoimmunotherapy depletes immunosuppressive cancer-associated fibroblasts and remodels local tumor immunity.

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME) play a critical role in tumor immunosuppression. However, targeted depletion of CAFs is difficult due to their diverse cells of origin and the resulting lack of specific surface markers. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer treatment that leads to rapid cell membrane damage. In this study, we used anti-mouse fibroblast activation protein (FAP) antibody to target FAP+ CAFs (FAP-targeted NIR-PIT) and investigated whether this therapy could suppress tumor progression and improve tumor immunity. FAP-targeted NIR-PIT induced specific cell death in CAFs without damaging adjacent normal cells. Furthermore, FAP-targeted NIR-PIT treated mice showed significant tumor regression in the CAF-rich tumor model accompanied by an increase in CD8+ tumor infiltrating lymphocytes (TILs). Moreover, treated tumors showed increased levels of IFN-γ, TNF-α, and IL-2 in CD8+ TILs compared with non-treated tumors, suggesting enhanced antitumor immunity. Cancers with FAP-positive CAFs in their TME grow rapidly and FAP-targeted NIR-PIT not only suppresses their growth but improves tumor immunosuppression. Thus, FAP-targeted NIR-PIT is a potential therapeutic strategy for selectively targeting the TME of CAF+ tumors.

Molecular and Clinicopathological Characteristics of Lung Cancer Concomitant Chronic Obstructive Pulmonary Disease (COPD).

IntroductionChronic obstructive pulmonary disease (COPD) and lung cancer often coexist, but its pathophysiology and genomics features are still unclear.MethodsIn this study, we retrospectively collected lung cancer concomitant COPD (COPD-LC) and non-COPD lung cancer (non-COPD-LC) patients, who performed next generation sequencing (NGS) and had clinicopathological information simultaneously. The COPD-LC data from the TCGA cohort were collected to conduct further analysis.ResultsA total of 51 COPD-LC patients and 88 non-COPD-LC patients were included in the study. Clinicopathological analysis showed that proportion of male gender, older age, and smoking patients were all substantially higher in COPD-LC group than in non-COPD-LC group (all P<0.01). Comparing the genomic data of the two groups in our cohort, COPD-LC had higher mutation frequency of LRP1B (43% vs 9%, P = 0.001), EPHA5 (24% vs 1%, P = 0.002), PRKDC (14% vs 1%, P = 0.039), PREX2 (14% vs 0%, P = 0.012), and FAT1 (14% vs 0%, P = 0.012), which had a relationship with improved tumor immunity. Immunotherapy biomarker of PD-L1 positive expression (62.5% vs 52.0%, P = 0.397) and tumor mutation burden (TMB, median TMB: 7.09 vs 2.94, P = 0.004) also were higher in COPD-LC. In addition, RNA data from TCGA further indicated tumor immunity increased in COPD-LC. Whereas, COPD-LC had lower frequency of EGFR mutation (19% vs 50%, P = 0.013) and EGFR mutant COPD-LC treated with EGFR-TKI had worse progression-free survival (PFS) (HR = 3.52, 95% CI: 1.27–9.80, P = 0.01).ConclusionIn this retrospective study, we first explored molecular features of COPD-LC in a Chinese population. Although COPD-LC had lower EGFR mutant frequency and worse PFS with target treatment, high PD-L1 expression and TMB indicated these patients may benefit from immunotherapy.

Clinical and genomic characteristics of lung cancer concomitant chronic obstructive pulmonary disease (COPD).

e15131 Background: Lung cancer and chronic obstructive pulmonary disease (COPD) often coexist. Lots of clinical and genomic descriptions related lung cancer have been investigated. However, the clinical and genomics characteristics of lung cancer coexisting COPD are still unclear. Herein, we explored the clinical characteristics and somatic mutational landscape of lung cancer coexisting COPD (COPD-LC) and compared with non-COPD Lung cancer (non-COPD-LC). Methods: We retrospectively collected total COPD-LC and non-COPD-LC patients who performed next generation sequencing (NGS) simultaneously from The Traditional Chinese Medicine Hospital Affiliated to Xinjiang Medical University during December 2018 to August 2021. And collected COPD-LC data from TCGA to further analysis. COPD was defined as incompletely reversible airflow obstruction associated with post-bronchodilator forced expiratory volume in one second (FEV1) and its ratio to forced vital capacity (FEV1/FVC) &lt; 0.7. Results: Of the 139 patients enrolled in the study, 51 were categorized as COPD and 88 as non-COPD. In our clinical cohort, compared with non-COPD-LC, amount of male gender, older age and smoking patients were significantly higher than non-COPD in term of clinical data (all P &lt; 0.01). As for somatic mutation in our cohort, compared with non-COPD-LC, COPD-LC had higher mutation frequency of LRP1B (43% vs 9%, P = 0.001), EPHA5 (24% vs 1%, P = 0.002), PRKDC (14% vs 1%, P = 0.039) and PREX2 (14% vs 0%, P = 0.012), which had relationship with improved tumor immunity. Immunotherapy biomarker of PD-L1 positive expression (62.5% vs 52.0%, P = 0.397) and TMB (P = 0.004) also were higher in COPD group. Whereas, COPD-LC had lower frequency of EGFR (19% vs 50%, P = 0.013). And survival analysis showed in EGFR mutant patients with targeted therapy, COPD-LC had worse PFS than non-COPD-LC (HR = 3.52, 95%CI: 1.27-9.80, P = 0.01). TCGA cohort mutation data differed from the results of our cohort. In addition, RNA data from TCGA indicated COPD-LC increased tumor immunity. Conclusions: In our research, COPD-LC had unique clinical and molecular features. High PD-L1 expression and TMB indicated these patients may benefit from immunotherapy. Notably, mutation difference between Chinese and TCGA cohort and COPD-LC immunotherapy efficacy need prospective further study.

Multi-material basis and multi-mechanisms of the Dahuang Zhechong pill for regulating Treg/Th1 balance in hepatocellular carcinoma

BackgroundDahuang Zhechong pill (DHZCP) improves the inhibitory immune status of mice with hepatocellular carcinoma (HCC) by regulating Treg/Th1 balance. Hypothesis/PurposeTo study the multi-material basis and multi-mechanisms of DHZCP against HCC by regulating Treg/Th1 balance in vitro and in vivo. MethodsUPLC-MS/MS was used to detect the dynamic changes in 29 characteristic components of different polar parts of DHZCP. H&E and TUNEL were used to check pathological condition in HCC mice. The number of CD4+T, CD8+T, Treg, Th1, and Th1-like Treg cells was counted by flow cytometry. TGF-β, IL-10, IFN-γ, and TNF-α content were detected by ELISA. α-Ketoglutarate and glutamine levels were detected by Trace1310/TSQ8000 GC-MS/MS. p-Smad2, and p-Smad3 protein levels were detected by WB, mRNA expression of Smad2, alanine-serine-cysteine transporter-2, glutaminase, and glutamate dehydrogenase were detected by RT-PCR. Simca-p multivariate data analysis software was used to evaluate the relationship between the different polar parts of DHZCP and the proportion of Treg cells. ResultsWater-soluble (PW) and ethyl acetate (PE) polar parts of DHZCP affected the HCC immune system by inhibiting the differentiation of Tregs, reversing the balance of Treg/Th1, and significantly reduced the tumor volume and weight. However, petroleum ether and n-butanol polar parts had no above actions. The changes in emodin, chrysophanol, aloe vera emodin, emodin-8-O-β-D-glycoside, gallic acid, naringenin, baicalein, wogonin, norwogonin, apigenin, chrysin, glycyrrhizin, formononetin, and palmitic acid were closely related to the changes of Treg cells, which is the main material basis of DHZCP inhibition of Treg differentiation. Additionally, PW mainly inhibit the differentiation of Treg cells by affecting the metabolism of hepatoma cells, improving tumor microenvironment acidity, and glutamine depletion. However, PE inhibited the differentiation of Treg cells mainly by regulating the TGF-β/Smad pathway. ConclusionIn this study, accurate analysis of multi-component was combined with pharmacodynamic evaluations to identify the pharmacodynamic substances of DHZCP in regulating Treg/Th1 balance, and clarified the multi-target mechanism of DHZCP to improve tumor immunity. The study style offers a novel approach for pharmacological research on TCM.

B cells imprint adoptively transferred CD8+ T cells with enhanced tumor immunity

BackgroundAdoptive T cell transfer (ACT) therapy improves outcomes in patients with advanced malignancies, yet many individuals relapse due to the infusion of T cells with poor function or persistence. Toll-like...

Immunogenic tumor cell death promotes dendritic cell migration and inhibits tumor growth via enhanced T cell immunity

SummaryImmunogenic tumor cell death enhances anti-tumor immunity. However, the mechanisms underlying this effect are incompletely understood. We established a system to induce tumor cell death in situ and investigated its effect on dendritic cell (DC) migration and T cell responses using intravital photolabeling in mice expressing KikGR photoconvertible protein. We demonstrate that tumor cell death induces phagocytosis of tumor cells by tumor-infiltrating (Ti)-DCs, and HMGB1-TLR4 and ATP-P2X7 receptor signaling-dependent Ti-DC emigration to draining lymph nodes (dLNs). This led to an increase in anti-tumor CD8+ T cells of memory precursor effector phenotype and secondary tumor growth inhibition in a CD103+ DC-dependent manner. However, combining tumor cell death induction with lipopolysaccharide treatment stimulated Ti-DC maturation and emigration to dLNs but did not improve tumor immunity. Thus, immunogenic tumor cell death enhances tumor immunity by increasing Ti-DC migration to dLNs where they promote anti-tumor T cell responses and tumor growth inhibition.

Neutralization of TGFβ Improves Tumor Immunity and Reduces Tumor Progression in Ovarian Carcinoma.

The immunosuppressive effects of TGFβ promotes tumor progression and diminishes response to therapy. In this study, we used ID8-p53-/- tumors as a murine model of high-grade serous ovarian cancer. An mAb targeting all three TGFβ ligands was used to neutralize TGFβ. Ascites and omentum were collected and changes in T-cell response were measured using flow. Treatment with anti-TGFβ therapy every other day following injection of tumor cells resulted in decreased ascites volume (4.1 mL vs. 0.7 mL; P < 0.001) and improved the CD8:Treg ratio (0.37 vs. 2.5; P = 0.02) compared with untreated mice. A single dose of therapy prior to tumor challenge resulted in a similar reduction of ascites volume (2.7 vs. 0.67 mL; P = 0.002) and increased CD8:Tregs ratio (0.36 vs. 1.49; P = 0.007), while also significantly reducing omental weight (114.9 mg vs. 93.4 mg; P = 0.017). Beginning treatment before inoculation with tumor cells and continuing for 6 weeks, we observe similar changes and prolonged overall survival (median 70 days vs. 57.5 days). TGFβ neutralization results in favorable changes to the T-cell response within the tumor microenvironment, leading to decreased tumor progression in ovarian cancer. The utilization of anti-TGFβ therapy may be an option for management in patients with ovarian cancer to improve clinical outcomes and warrants further investigation.

The GM-CSF-IRF5 signaling axis in eosinophils promotes antitumor immunity through activation of type 1 T cell responses.

The depletion of eosinophils represents an efficient strategy to alleviate allergic asthma, but the consequences of prolonged eosinophil deficiency for human health remain poorly understood. We show here that the ablation of eosinophils severely compromises antitumor immunity in syngeneic and genetic models of colorectal cancer (CRC), which can be attributed to defective Th1 and CD8+ T cell responses. The specific loss of GM-CSF signaling or IRF5 expression in the eosinophil compartment phenocopies the loss of the entire lineage. GM-CSF activates IRF5 in vitro and in vivo and can be administered recombinantly to improve tumor immunity. IL-10 counterregulates IRF5 activation by GM-CSF. CRC patients whose tumors are infiltrated by large numbers of eosinophils also exhibit robust CD8 T cell infiltrates and have a better prognosis than patients with eosinophillow tumors. The combined results demonstrate a critical role of eosinophils in tumor control in CRC and introduce the GM-CSF-IRF5 axis as a critical driver of the antitumor activities of this versatile cell type.

A novel combination of chemotherapy and immunotherapy controls tumor growth in mice with a human immune system

ABSTRACTMice reconstituted with a human immune system and bearing human tumors represent a promising model for developing novel cancer immunotherapies. Here, we used mass cytometry and multi-parametric flow cytometry to characterize human leukocytes infiltrating a human breast cancer tumor model in immunocompromised NOD.SCID.γc-null mice reconstituted with a human immune system and compared it to samples of breast cancer patients. We observed highly activated human CD4+ and CD8+ T cells in the tumor, as well as minor subsets of innate immune cells in both settings. We also report that ICOS+ CD4+ regulatory T cells (Treg) were enriched in the tumor relative to the periphery in humanized mice and patients, providing a target to affect Treg and tumor growth. Indeed, administration of a neutralizing mAb to human ICOS reduced Treg proportions and numbers and improved CD4 + T cell proliferation in humanized mice. Moreover, a combination of the anti-ICOS mAb with cyclophosphamide reduced tumor growth, and that was associated with an improved CD8 to Treg ratio. Depletion of human CD8+ T cells or of murine myeloid cells marginally affected the effect of the combination therapy. Altogether, our results indicate that a combination of anti-ICOS mAb and chemotherapy controls tumor growth in humanized mice, opening new perspectives for the treatment of breast cancer.One sentence summary: Targeting ICOS in combination with chemotherapy is a promising strategy to improve tumor immunity in humans.

C-106 Tumor targeting antibodies to improve tumor immunity: The role of microbiota

Tumor cells express a panel of surface molecules to promote their growth and evade immune responses, such as oncogenic receptors, PD-L1, andCD47. Tumor targeting antibodies have been designed to kill tumor cells. Several mechanisms have been proposed, including stress-induced apoptosis, antibody-dependent cytotoxicity, complement dependent cytotoxicity, and increased phagocytosis. We have now observed that anti-Her2/neu-mediated tumor regression depends on MyD88, interferon, CD4+ or CD8+ T cells. Anti-CD20 mediated tumor eradication depends on IFN and CD8. CD47 is highly expressed stem-like cancer cells that are more resistant to conventional treatment. Using xenograft and in vitro models, anti-CD47antibody (Ab) that blocks SIRP signaling by CD47 is thought to enhance “eat me” signaling to kill tumor cells by macrophage-mediated phagocytosis. Our study is revealing that local anti-CD47 antibody regresses tumor cells depending on cGAS/STING but not MyD88, IFN, and CD8+ T cells. Therefore, our studies have now revealed a distinct mechanism for antibody-mediated tumor regression that include different innate sensing and adaptive pathways and open new avenues for combinational therapies with other conventional drugs andimmunotherapy. We have further observed that the anti-tumor efficacy of anti-CD47 antibody blockade relies on the gut microbiota. Gut microbiota are generally hypothesized to influence anti-tumor responses by initiating gut immunity. However, we observed the primary site of enhancing anti-tumor immunity is inside tumor by microbiota. Furthermore, intratumoral administration of a microbiota isolated from tumor tissues restore anti-tumor immunity in non-responder of anti-CD47 treatment. Together, our study has identified gut microbiota colonized in the tumor sites facilitates CD47-based immunotherapy by STING signaling and has applicability to improve anti-CD47 immunotherapy.

Abstract B02: Targeting CSK kinase activity to enhance antitumor immunity

Abstract To mount an effective tumor immune response, a T cell receptor (TCR) must first recognize a cognate antigen presented by the malignant cells. This antigen-TCR engagement at the cell surface initiates an intracellular signaling cascade that leads to the upregulation of pro-inflammatory and cytolytic cytokines. Successful effector T cell activation in turn results in the elimination of antigen-presenting diseased cells. A key regulator of this signaling cascade is the C-terminal Src (CSK) kinase. In lymphocytes CSK inhibits T cell activation by phosphorylating the SRC kinase family member LCK at tyrosine 505 and thereby terminates the signaling cascade. To assess whether relieving an intracellular blockade of TCR signaling will lead to a more robust T cell response, and hence improved tumor immunity, we developed both genetic and pharmacologic approaches to inhibit CSK activity. A tamoxifen-inducible transgenic CSK knock-out mice was engineered to bypass the embryonic lethality observed with constitutive systemic CSK depletion. As expected loss of CSK enhanced cytokine production and increased anti-tumor immune response in the MC38 syngeneic tumor mouse model. Potent and selective CSK small molecule inhibitors, in the presence of TCR stimulation, similarly activated the proximal TCR signaling pathway and increased cytokine production and proliferation. In an in vivo efficacy study, however, the CSK inhibitor as monotherapy or in combination with aPD1 did not improve anti-tumor immune response at the dose levels tested. This seemingly discrepant finding in tumor response observed in the tamoxifen-inducible KO mice and mice treated with the CSK inhibitor may reflect the need for further optimization in target coverage and dosing regimen. In this poster, we will present our findings on the role of CSK inhibition in tumor immunity. Citation Format: Cindy Wang, Carolyn Cao, Lisa Berman-Booty, Ruki Eraslan, Miguel Sanjuan, Gregory Vite, Jack Hunt, Brian Fink, Susan Wee. Targeting CSK kinase activity to enhance antitumor immunity [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr B02.

Abstract B198: Targeting CSK kinase activity to enhance antitumor immunity

Abstract To mount an effective immune response, a T-cell receptor (TCR) must first recognize a cognate antigen presented by malignant cells. Successful effector T-cell activation initiates an intracellular signaling cascade that results in the release of cytotoxins and proinflammatory cytokines that ultimately result in the elimination of antigen-presenting diseased cells. A key regulator of this signaling cascade is the C-terminal Src (CSK) kinase. In lymphocytes CSK inhibits T-cell activation by phosphorylating the SRC kinase family member LCK at tyrosine 505 and thereby terminates the signaling cascade. To assess whether relieving an intracellular blockade of TCR signaling will lead to a more robust T-cell response, and hence improved tumor immunity, we developed both genetic and pharmacologic approaches to inhibit CSK activity. A tamoxifen-inducible transgenic CSK knockout mouse was engineered to bypass the embryonic lethality observed with constitutive systemic CSK depletion. As expected, loss of CSK enhanced cytokine production and increased antitumor immune response in the MC38 syngeneic tumor mouse model. Potent and selective CSK small-molecule inhibitors, in the presence of TCR stimulation, similarly activated the proximal TCR signaling pathway and increased cytokine production and proliferation. In an in vivo efficacy study, however, the CSK inhibitor as monotherapy or in combination with aPD1 did not improve antitumor immune response at the dose levels tested. This seemingly discrepant finding in tumor response observed in the tamoxifen-inducible KO mice and mice treated with the CSK inhibitor may reflect the need for a more optimized dosing regimen and target coverage. In this poster, we will present our findings on the role of CSK inhibition in tumor immunity. Citation Format: Cindy Wang, Carolyn Cao, Lisa Berman-Booty, Jesse Swanson, Rukiye Eraslan, Miguel Sanjuan, Gregory Vite, Lan-Ying Qin, John Hunt, Brian Fink, Susan Wee. Targeting CSK kinase activity to enhance antitumor immunity [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B198.

330 Deficiency of Bach2 results in improved tumor immunity by enhancing effector function in CD8 T cells

330 Deficiency of Bach2 results in improved tumor immunity by enhancing effector function in CD8 T cells

Deficiency of Bach2 results in improved tumor immunity by enhancing effector function in CD8+ T cells

Deficiency of Bach2 results in improved tumor immunity by enhancing effector function in CD8+ T cells

Manipulation of IL-2 signals by IL-2/antibody complex and CD25 blockade improves tumor immunity, reprograms regulatory T cells, and augments CD8+ central memory in an ovarian cancer model

Abstract We used a defined IL-2/αIL-2 complex that directs IL-2 to stimulate only intermediate-affinity IL-2 receptor (CD122/132) to promote tumor rejection and avoid regulatory T cell (Treg) expansion. However, it is unknown if IL-2/αIL-2 alters Treg function, as Tregs also express CD122/132. After challenge with ID8agg ovarian cancer (OC) cells, IL-2/αIL-2 greatly reduced tumor burden, and increased IFN-γ, TNF-α, CD44, and CD25 in CD4+ non-Tregs and CD8+ T cells, as expected. IL-2/αIL-2 was clinically effective, yet it lowered the ascites CD8+/FoxP3+ Treg ratio and increased per cell FoxP3 levels in Tregs, suggesting a change in Treg function. IL-2/αIL-2 decreased the ratio of CD62L+ central Tregs to CD44+ effector Tregs in ID8agg ascites, indicating modulation of Treg differentiation. Surprisingly, ascites Tregs produced IFN-γ, IL-2, and TNF-α in control-treated OC mice, which was abolished by IL-2/αIL-2, suggesting further alteration of Treg differentiation and function. CD25 (high-affinity IL-2 receptor subunit) expression on Tregs was reduced by IL-2/αIL-2, which could lower Treg IL-2 sequestration and increase IL-2 available to antitumor T cells. CD25 blockade with αCD25 during IL-2/αIL-2 treatment reduced clinical efficacy but greatly increased central memory (CM; CD62L+CD44+) CD8+ T cells in blood and mesenteric (tumor-draining) lymph nodes. Thus, reduction of tumor burden by IL-2/αIL-2 is associated with reprogramming of Treg differentiation and function in an OC model. CD25 blockade after IL-2/αIL-2 could improve response durability by boosting CM CD8+ formation. These data demonstrate novel effects of IL-2-modulating drugs on Tregs and CD8+ memory and will aid development of more effective anticancer immunotherapy.

Targeting CD8+ T-cell tolerance for cancer immunotherapy.

In the final issue of Science in 2013, the American Association of Science recognized progress in the field of cancer immunotherapy as the 'Breakthrough of the Year.' The achievements were actually twofold, owing to the early success of genetically engineered chimeric antigen receptors (CAR) and to the mounting clinical triumphs achieved with checkpoint blockade antibodies. While fundamentally very different, the common thread of these independent strategies is the ability to prevent or overcome mechanisms of CD8(+) T-cell tolerance for improved tumor immunity. Here we discuss how circumventing T-cell tolerance has provided experimental insights that have guided the field of clinical cancer immunotherapy to a place where real breakthroughs can finally be claimed.

Augmenting Antitumor T-Cell Responses to Mimotope Vaccination by Boosting with Native Tumor Antigens

Vaccination with antigens expressed by tumors is one strategy for stimulating enhanced T-cell responses against tumors. However, these peptide vaccines rarely result in efficient expansion of tumor-specific T cells or responses that protect against tumor growth. Mimotopes, or peptide mimics of tumor antigens, elicit increased numbers of T cells that crossreact with the native tumor antigen, resulting in potent antitumor responses. Unfortunately, mimotopes may also elicit cells that do not crossreact or have low affinity for tumor antigen. We previously showed that one such mimotope of the dominant MHC class I tumor antigen of a mouse colon carcinoma cell line stimulates a tumor-specific T-cell clone and elicits antigen-specific cells in vivo, yet protects poorly against tumor growth. We hypothesized that boosting the mimotope vaccine with the native tumor antigen would focus the T-cell response elicited by the mimotope toward high affinity, tumor-specific T cells. We show that priming T cells with the mimotope, followed by a native tumor-antigen boost, improves tumor immunity compared with T cells elicited by the same prime with a mimotope boost. Our data suggest that the improved tumor immunity results from the expansion of mimotope-elicited tumor-specific T cells that have increased avidity for the tumor antigen. The enhanced T cells are phenotypically distinct and enriched for T-cell receptors previously correlated with improved antitumor immunity. These results suggest that incorporation of native antigen into clinical mimotope vaccine regimens may improve the efficacy of antitumor T-cell responses.

Abstract 4742: Anti-tyrosinase related protein 1 (TRP1) antibody combined with cyclophosphamide induces adaptive immunity against melanoma

Abstract Monoclonal antibodies targeting tumor antigens are an effective anti-cancer immunotherapy, with well established benefit against multiple tumor types. They are most potent when given in combination with chemotherapy. The mechanisms underlying the efficacy of combination therapy, however, are poorly understood.1 Tyrosinase-related protein 1 (TRP1) is a protein implicated in pigment formation. TRP1 is found primarily in the melanosome, but surface expression can be detected in vivo. An antibody targeting TRP1 is currently in clinical testing. In mice, anti-TRP1 prophylaxis controls subsequent growth of B16 melanoma, but has minimal activity as a single agent against established disease.2 We have previously shown that anti-TRP1 enhances T cell responses induced by DNA vaccination.3 We now report that anti-TRP1 enhances the cytotoxic effect of cyclophosphamide chemotherapy in the treatment of established cutaneous B16 melanoma. We find considerable efficacy when anti-TRP1 is combined with cyclophosphamide chemotherapy with treatment initiated at timepoints up to day 7 when tumors are palpable with long term disease control observed in some animals. Treatment is ineffective in mice deficient in the Fc receptor common γ chain. Combination therapy is associated with increased infiltration of tumors by CD8+ T lymphocytes visualized by immunofluorescence (IF) and flow cytometry. Mice receiving combination therapy have increased infiltration by CD4+foxp3- T cells, but not by CD4+foxp3+ T cells. Therapeutic efficacy was decreased but not abrogated in animals depleted of CD8+ T cells through injection of anti-CD8 IgG. Surprisingly, although B16 is a non-immunogenic tumor, surviving mice treated with cyclophosphamide and ‘passive’ immunization with anti-TRP1 displayed resistance to repeat inoculation with B16 melanoma. These data strongly implicate a role for adaptive immunity in the therapeutic efficacy of anti-tumor antibodies combined with chemotherapy and has implications for design of future clinical trials using these agents and for the development of novel strategies to induce adaptive anti-tumor immunity. 1. Ferris RL, Jaffee EM, Ferrone S. Tumor antigen-targeted, monoclonal antibody-based immunotherapy: clinical response, cellular immunity, and immunoescape. J Clin Oncol 2010;28:4390-9. 2. Hara I, Takechi Y, Houghton AN. Implicating a role for immune recognition of self in tumor rejection: passive immunization against the brown locus protein. J Exp Med 1995;182:1609-14. 3. Saenger YM, Li Y, Chiou KC, et al. Improved tumor immunity using anti-tyrosinase related protein-1 monoclonal antibody combined with DNA vaccines in murine melanoma. Cancer Res 2008;68:9884-91. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4742. doi:10.1158/1538-7445.AM2011-4742

UV Exposure Boosts Transcutaneous Immunization and Improves Tumor Immunity: Cytotoxic T-Cell Priming through the Skin

Immunologic approaches to combat cancer aim at the induction of tumor-reactive immune responses to achieve long-term protection. In this context, we recently developed a transcutaneous immunization (TCI) method using the Toll-like receptor (TLR) 7 agonist imiquimod and a peptide epitope. Application onto intact skin induces potent cytotoxic T lymphocyte (CTL) responses and protection against transplanted tumors. The purpose of this study was to explore the effects of UV irradiation on imiquimod-based TCI. Here we show that skin exposure to low-dose UV light before TCI with imiquimod strongly boosts specific CTL responses leading to memory formation and enhanced tumor protection. Toward the mechanisms, we show that the activation of bone-marrow-derived dermal dendritic cells (DCs), but not Langerin-expressing DCs, is responsible for enhanced CTL activation. We describe an optimized TCI method that mediates enhanced CTL and antitumor responses by a DC- and TLR-dependent mechanism. These data may provide the basis for the future development of advanced vaccination protocols against tumors and persistent virus infections.