IL-13 is produced by tumor cells in breast implant-associated anaplastic large cell lymphoma: implications for pathogenesis

More than 500 women worldwide have developed a CD30+ T-cell lymphoma around breast implants, strongly suggesting a cause-and-effect relationship, and designated as breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). The mechanism of lymphomagenesis is unknown. Recently, a bacterial biofilm containing gram-negative bacilli was discovered on the surface of breast implants associated with ALCL. We and others have described overexpression of the proto-oncogene JUNB and mutations of JAK1/2, TP53 and STAT3 in BIA-ALCL. Here we report that BIA-ALCL cell lines and anaplastic lymphoma cells in clinical specimens produce IL-13, the signature cytokine of allergic inflammation. Supporting the link of BIA-ALCL to allergic inflammation, lymphoma cells were often surrounded by eosinophils and mast cells, features typically absent in systemic ALCL. Because of the link of IL-13 to allergy, we looked for IgE and found it decorating the surface of mast cells and antigen-presenting follicular dendritic cells in capsules and lymph nodes infiltrated by anaplastic lymphoma cells, but not uninvolved capsules. Plasma cells within capsules and regional lymph nodes were identified as a possible source of IgE. Together, these findings suggest the hypothesis that an amplified immune response with features of a chronic allergic reaction in a susceptible patient underlies the pathogenesis of BIA-ALCL.

OX40 signaling Induces Canonical Antigen Presentation-independent Proliferation of Human and Murine Thymic Regulatory T-cells

Regulatory T-cells (Tregs) play a pivotal role in immune-tolerance, and loss of their function can lead to autoimmunity. Natural Tregs generated in the thymus contribute substantially to the Treg pool in the periphery where they suppress self-reactive Teff responses. Recently, we showed that OX40L (TNFSF4) can drive selective proliferation of peripheral Tregs independent of canonical antigen presentation (CAP-independent) in the presence of low dose IL-2. Therefore, we reasoned that OX40 signaling might be integral to the TCR-independent phase of murine and human thymic Treg (tTreg) development. Thymic Treg development is a two-step process: Strong T-cell receptor (TCR) signals combined with co-signals from the TNF receptor Super Family (TNFRSF) members facilitate tTreg precursor selection, followed by a TCR-independent phase of tTreg development when their maturation is driven by IL-2. Therefore, we investigated whether OX40 signaling can also play a critical role in the TCR-independent phase of tTreg development. OX40−/− mice had significantly reduced numbers of CD25−Foxp3low tTreg precursors and CD25+Foxp3+ matured tTregs, while OX40L treatment of WT mice induced significant proliferation of these cell subsets. Relative to tTeffs cells, OX40 was expressed at higher levels in both murine and human tTreg precursors and matured tTregs. In ex vivo cultures, OX40L increased tTreg maturation and induced CAP-independent proliferation of both murine and human tTregs which was mediated through the activation of AKT-mTOR signaling. These novel findings show an evolutionarily conserved role for OX40 signaling in tTreg development.

Treatment of a Patient with b Cell Lymphoma by 1-131 Lym-1 Monoclonal Antibodies

A patient with Richter's syndrome, a malignant lymphomatous transformation of chronic lymphocytic leukemia, had become moribund with rapidly enlarging masses, granulocytopenia and thrombocytopenia despite the use of conventional chemotherapy and radiotherapy. Greater than ten percent of a test dose of I-131 Lym-1, a murine monoclonal antibody produced against Burkitt's African B cell lymphoma, was accumulated by her tumor. The patient was subsequently treated with a series of injections of I-131 Lym-1 with dramatic clinical response, reduction of tumor volume by x-ray computerized tomography and progression of circulating cellular elements toward normality. Her course over the next ten months was not like that to be expected for Richter's syndrome, which has an average survival of four months. This mode of treatment appears promising.

Critical role of OX40 signaling in the TCR-independent phase of human and murine thymic Treg generation

Regulatory T cells (Tregs) play a pivotal role in immune-tolerance, and loss of Treg function can lead to the development of autoimmunity. Natural Tregs generated in the thymus substantially contribute to the Treg pool in the periphery, where they suppress self-reactive effector T cells (Teff) responses. Recently, we showed that OX40L (TNFSF4) is able to drive selective proliferation of peripheral Tregs independent of canonical antigen presentation (CAP-independent) in the presence of low-dose IL-2. Therefore, we hypothesized that OX40 signaling might be integral to the TCR-independent phase of murine and human thymic Treg (tTreg) development. Development of tTregs is a two-step process: Strong T-cell receptor (TCR) signals in combination with co-signals from the TNFRSF members facilitate tTreg precursor selection, followed by a TCR-independent phase of tTreg development in which their maturation is driven by IL-2. Therefore, we investigated whether OX40 signaling could also play a critical role in the TCR-independent phase of tTreg development. OX40^-/- mice had significantly reduced numbers of CD25^-Foxp3^low tTreg precursors and CD25⁺Foxp3⁺ mature tTregs, while OX40L treatment of WT mice induced significant proliferation of these cell subsets. Relative to tTeff cells, OX40 was expressed at higher levels in both murine and human tTreg precursors and mature tTregs. In ex vivo cultures, OX40L increased tTreg maturation and induced CAP-independent proliferation of both murine and human tTregs, which was mediated through the activation of AKT-mTOR signaling. These novel findings show an evolutionarily conserved role for OX40 signaling in tTreg development and proliferation, and might enable the development of novel strategies to increase Tregs and suppress autoimmunity.

Relationship between neutrophil lymphocyte ratio (NLR) and MDSC concentration in localized and metastatic castration resistant prostate cancer (mCRPC) patients

338

Background: Human Myeloid Derived Suppressor Cells (MDSCs) have gained recognition as a significant population of cells that arise in cancer patients to mediate immune tolerance. MDSCs have been validated as a prognostic factor in several tumor types. The Neutrophil-Lymphocyte Ratio (NLR) is an easily obtained marker of inflammation that has also been validated as a prognostic marker in tumors including prostate cancer. We measured and compared MDSC concentrations and NLR in a cohort of patients with prostate cancer and also examined thier relationship with PSA Progression, a validated marker of overall survival. Methods: Blood was collected from patients with localized prostate cancer (n = 14) and mCRPC (n = 44) at 0 and 6 months. The percent CD33+ HLA-DRlow HIF1a+, CD33+ HLADRlow C/EBPb+, CD11b+ HLA-DRlow HIF1a+, and CD11b+ HLA-DRlow C/EBPb+cells as a fraction of PBMC were determined and reported. NLRs were obtained within 4 weeks of MDSC measurements. Patients were followed for a period of 2 years; PSA-Progression (PSA-P) was defined as a PSA doubling time of < 3 months in association with an increase of at least > 5ng/mL from PSA nadir Results: Higher Gleason scores were statistically associated with a NLR of greater than 2 (r = 0.07, p = 0.02, 95% CI [0.01-0.14]). Increasing MDSC% did not correlate with increasing Gleason scores (r = 0.13, p = 0.31) or predict PSA-P at 6 months (p = 0.16). MDSC% in patients with mCRPC (4.25%, 95% CI[3.34-5.17]) were significantly higher than localized prostate cancer (1.7%, 95% CI[1.02-2.37]) . There was a highly statistically significant relationship between the percentage of MDSC in PBMC with the neutrophil lymphocyte ratio (r = 0.68, p = 0.001, 95% CI [0.31-1.05]). Conclusions: MDSC concentrations in metastatic prostate cancer patients are significantly higher than those with localized disease and are associated with an increased neutrophil lymphocyte ratio. Although a trend was detected towards MDSC% predicting PSA-P, in this limited sample it was not statistically significant.

MDSC clinical assay for cancer detection and monitoring in renal cell carcinoma

TPS713

Background: Human Myeloid Derived Suppressor Cells (MDSCs) have gained recognition as a significant population of cells that arise in cancer patients to mediate immune tolerance. Some studies have shown MDSC concentrations to be associated with overall survival and response to therapy in renal cell carcinoma. MDSCs comprise a heterogenous population that are yet to be fully characterized. We have identified a set of biomarkers uniquely expressed by the suppressive human MDSC phenotype and have developed an assay targeted to these markers. MDSCs are potentially a relatively cheap and easily performed screening and monitoring tool in cancers. This study will examine how a proprietary clinical assay works in detecting and monitoring MDSCs in blood and urine samples from patients with localized or metastatic renal cell cancer. Methods: The pilot research trial will enroll 63 subjects in a 1:1:1 ratio in three groups, normal controls over age 40 without evidence of any malignancy, patients with metastatic disease and localized renal cell carcinoma prior to nephrectomy. This sample size provides 80% power to detect a 1SD difference in MDSC concentrations in these groups on an F test. Blood and urine samples will be drawn at baseline and at 4 months for comparison. The percent CD33+ HLA-DRlow HIF1a+, CD33+ HLADRlow C/EBPb+, CD11b+ HLA-DRlow HIF1a+, and CD11b+ HLA-DRlow C/EBPb+cells as a fraction of PBMC will be determined. Primary Outcome Measures will be 1. Change in MDSC levels in patients with known localized renal cell carcinoma who undergo surgical treatment. 2. Change in MDSC level in patients with known metastatic renal cell carcinoma who initiate systemic treatment and 3. The direction and magnitude of the changes compared with radiographically assessed tumor burden. Secondary outcome measures are to assess MDSC level measurements in urine cytology analysis at baseline and after treatment to determine whether the two tests correlate in any of the 3 groups of patients defined in this study. Conclusion: This pilot study will examine if a MDSC clinical assay works in detecting and monitoring MDSCs. Recruitment is open to patients at the USC Cancer center and LAC+USC medical center. Clinical trial information: NCT02664883.

MDSC clinical assay for cancer detection and monitoring in urothelial carcinoma

TPS110

Background: Human Myeloid Derived Suppressor Cells (MDSCs) have gained recognition as a significant population of cells that arise in cancer patients to mediate immune tolerance. Some studies have shown MDSC concentrations to be associated with overall survival and response to therapy in urothelial carcinoma. MDSCs comprise a heterogenous population that are yet to be fully characterized. We have identified a set of biomarkers uniquely expressed by the suppressive human MDSC phenotype and have developed an assay targeted to these markers. MDSCs are potentially a relatively cheap and easily performed screening and monitoring tool in cancers. This study will examine how a proprietary clinical assay works in detecting and monitoring MDSCs in blood and urine samples from patients with or without localized or metastatic bladder cancer. Methods: The pilot research trial will enroll 63 subjects in a 1:1:1 ratio in three groups, normal controls over age 40 without evidence of any malignancy, patients with metastatic disease and localized muscle invasive disease prior to cystectomy. This sample size provides 80% power to detect a 1SD difference in MDSC concentrations in these groups on an F test. Blood and urine samples will be drawn at baseline and at 4 months for comparison. The percent CD33+ HLA-DRlow HIF1a+, CD33+ HLADRlow C/EBPb+, CD11b+ HLA-DRlow HIF1a+, and CD11b+ HLA-DRlow C/EBPb+cells as a fraction of PBMC will be determined. Primary Outcome Measures will be 1. Change in MDSC levels in patients with known localized, muscle-invasive bladder cancer who undergo neoadjuvant and surgical treatment. 2. Change in MDSC level in patients with known metastatic bladder cancer who undergo systemic treatment and 3. The direction and magnitude of the changes compared with radiographically assessed tumor burden. Secondary outcome measures are to assess MDSC level measurements in urine cytology analysis at baseline and after treatment to determine whether the two tests correlate in any of the 3 groups of patients defined in this study. Conclusion: This pilot study will examine if a MDSC clinical assay works in detecting and monitoring MDSCs. Recruitment is open to patients at the USC Cancer center and LAC+USC medical center. Clinical trial information: NCT02735512.

Lym-1 Chimeric Antigen Receptor T Cells Exhibit Potent Anti-Tumor Effects against B-Cell Lymphoma

T cells expressing chimeric antigen receptors (CARs) recognizing CD19 epitopes have produced remarkable anti-tumor effects in patients with B-cell malignancies. However, cancer cells lacking recognized epitopes can emerge, leading to relapse and death. Thus, CAR T cells targeting different epitopes on different antigens could improve immunotherapy. The Lym-1 antibody targets a conformational epitope of Human Leukocyte Antigen-antigen D Related (HLA-DR) on the surface of human B-cell lymphomas. Lym-1 CAR T cells were thus generated for evaluation of cytotoxic activity towards lymphoma cells in vitro and in vivo. Human T cells from healthy donors were transduced to express a Lym-1 CAR, and assessed for epitope-driven function in culture and towards Raji xenografts in NOD-scidIL2Rgamma^null (NSG) mice. Lym-1 CAR T cells exhibited epitope-driven activation and lytic function against human B-cell lymphoma cell lines in culture and mediated complete regression of Raji/Luciferase-Green fluorescent protein (Raji/Luc-GFP) in NSG mice with similar or better reactivity than CD19 CAR T cells. Lym-1 CAR transduction of T cells is a promising immunotherapy for patients with Lym-1 epitope positive B-cell malignancies.

PKC-ѳ is dispensable for OX40L-induced TCR-independent Treg proliferation but contributes by enabling IL-2 production from effector T-cells

We have previously shown that OX40L/OX40 interaction is critical for TCR-independent selective proliferation of Foxp3⁺ Tregs, but not Foxp3^- effector T-cells (Teff), when CD4⁺ T-cells are co-cultured with GM-CSF derived bone marrow dendritic cells (G-BMDCs). Events downstream of OX40L/OX40 interaction in Tregs responsible for this novel mechanism are not understood. Earlier, OX40L/OX40 interaction has been shown to stimulate CD4⁺ T-cells through the formation of a signalosome involving TRAF2/PKC-Ѳ leading to NF-kB activation. In this study, using CD4⁺ T-cells from WT and OX40^-/- mice we first established that OX40 mediated activation of NF-kB was critical for this Treg proliferation. Although CD4⁺ T-cells from PKC-Ѳ^-/- mice were also defective in G-BMDC induced Treg proliferation ex vivo, this defect could be readily corrected by adding exogenous IL-2 to the co-cultures. Furthermore, by treating WT, OX40^-/-, and PKC-Ѳ^-/- mice with soluble OX40L we established that OX40L/OX40 interaction was required and sufficient to induce Treg proliferation in vivo independent of PKC-Ѳ status. Although PKC-Ѳ is dispensable for TCR-independent Treg proliferation per se, it is essential for optimum IL-2 production by Teff cells. Finally, our findings suggest that OX40L binding to OX40 likely results in recruitment of TRAF1 for downstream signalling.

PKC-θ is dispensable for OX40L-induced TCR-independent Treg proliferation

Previously, we have shown that GM-CSF-induced Bone marrow-derived dendritic cells (G-BMDCs), upon co-culture with splenic CD4+ T cells, have the capability to induce preferential proliferation of regulatory T cells (Tregs) in TCR-independent and OX40L/OX40 dependent manner. In this study we investigated the signaling involved in this Treg proliferation induced by G-BMDCs. Firstly, using splenic CD4+ T cells from OX40 deficient mice and G-BMDCs from WT mice, we confirmed the important role of OX40L/OX40 interaction in Treg expansion. Since OX40 stimulation in the absence of TCR engagement has been reported to induce the assembly of a signalosome involving PKC-θ, we investigated the requirement of PKC-θ in our Treg proliferation mechanism. Interestingly, PKC-θ deficient-CD4+ T cells showed impaired Treg proliferation upon co-culture with WT G-BMDCs. However, this defect in proliferation could be rescued upon IL-2 addition suggesting that PKC-θ was dispensable for Treg proliferation. We further demonstrated that PKC-θ was essential for T-effectors to provide IL-2, which was required for OX40L/OX40-induced Treg proliferation. Furthermore, injecting WT, OX40- deficient, and PKC-θ-deficient mice with soluble OX40L, we established that OX40L/OX40 signaling was sufficient to induce in vivo expansion of Tregs in WT and PKC- deficient mice, but not in OX40-deficient mice. Finally, our data suggested a possible involvement of TRAF1 in Tregs, downstream of OX40 activation.

Critical role for OX40 signaling in Thymic and Peripheral Treg Expansion

Regulatory T-cells (Treg) play a pivotal role in suppressing self-reactive effector T-cells (Teff) and help maintain the critical balance between self-tolerance and autoimmunity. Restoration of homeostatic balance between Teff/Treg cells has been shown to ameliorate many autoimmune diseases including type-1 diabetes. Recently, we have reported a novel strategy for the selective expansion of Tregs using OX40L (a TNF-superfamily ligand) and Jagged (JAG)-1 (a Notch family ligand) treatment independent of canonical TCR-signaling, but mediated through specific interaction between OX40L-OX40 and JAG1-Notch3 preferentially expressed on Tregs. OX40L-JAG1 treatment of NOD mice with soluble OX40L and JAG1 increased proliferation of peripheral Tregs and delayed the onset of diabetes. In the present study, we show that OX40L treatment significantly increased Tregs in the thymus by inducing proliferation of thymic Tregs independent of TCR-stimulation upon addition of exogenous IL-2. OX40−/− mice had reduced numbers of thymic Tregs compared to wild type (WT) controls. The reduction in thymic Treg numbers likely due to impaired ability of proliferation in response to OX40L. However, we did not observe any change in IL-2 sensitivity of thymocytes in OX40−/− mice. Mechanistic studies suggested that OX40L-IL-2 induced thymic Treg proliferation was mediated through NF-kB and AKT-mTOR-S6 signaling. Further, phenotypic characterization studies revealed a significant decrease in TIGIT+Treg population, often associated with Treg activation, in both thymus and spleen of OX40−/− mice compared to WT controls. Taken together, these results suggest a critical role for OX40L/OX40 signaling in the development as well as function of Tregs.

Soluble OX40L and JAG1 Induce Selective Proliferation of Functional Regulatory T-Cells Independent of canonical TCR signaling

Regulatory T-cells (Tregs) play a pivotal role in maintaining peripheral tolerance. Increasing Treg numbers/functions has been shown to ameliorate autoimmune diseases. However, common Treg expansion approaches use T-Cell Receptor (TCR)-mediated stimulation which also causes proliferation of effector T-cells (Teff). To overcome this limitation, purified patient-specific Tregs are expanded ex vivo and transfused. Although promising, this approach is not suitable for routine clinical use. Therefore, an alternative approach to selectively expand functional Tregs in vivo is highly desired. We report a novel TCR-independent strategy for the selective proliferation of Foxp3+Tregs (without Teff proliferation), by co-culturing CD4+ T-cells with OX40 L+Jagged(JAG)-1+ bone marrow-derived DCs differentiated with GM-CSF or treating them with soluble OX40 L and JAG1 in the presence of exogenous IL-2. Tregs expanded using soluble OX40 L and JAG1 were of suppressive phenotype and delayed the onset of diabetes in NOD mice. Ligation of OX40 L and JAG1 with their cognate-receptors OX40 and Notch3, preferentially expressed on Tregs but not on Teff cells, was required for selective Treg proliferation. Soluble OX40L-JAG1-induced NF-κB activation as well as IL-2-induced STAT5 activation were essential for the proliferation of Tregs with sustained Foxp3 expression. Altogether, these findings demonstrate the utility of soluble OX40 L and JAG1 to induce TCR-independent Treg proliferation.

Biomarkers Provide Clues to Early Events in the Pathogenesis of Breast Implant-Associated Anaplastic Large Cell Lymphoma

Almost 200 women worldwide have been diagnosed with breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). The unique location and specific lymphoma type strongly suggest an etio-pathologic link between breast implants and BIA-ALCL. It is postulated that chronic inflammation via bacterial infection may be an etiological factor. BIA-ALCL resembles primary cutaneous ALCL (pcALCL) in morphology, activated T-cell phenotype, and indolent clinical course. Gene expression array analysis, flow cytometry, and immunohistochemistry were used to study pcALCL and BIA-ALCL cell lines. Clinical samples were also studied to characterize transcription factor and cytokine profiles of tumor cells and surrounding lymphocytes. BIA-ALCL and pcALCL were found to have common expression of transcription factors SOCS3, JunB, SATB1, and a cytokine profile suggestive of a Th1 phenotype. Similar patterns were observed in a CD30+ cutaneous lymphoproliferative disorder (LPD). The patterns of cytokine and transcription factor expression suggest that BIA-ALCL is likely to arise from chronic bacterial antigen stimulation of T-cells. Further analysis of cytokine and transcription factor profiles may allow early detection and treatment of BIA-ALCL leading to better prognosis and survival. LEVEL OF EVIDENCE 5: Risk.

Age-dependent divergent effects of OX40L treatment on the development of diabetes in NOD mice

Earlier, we have shown that GM-CSF derived bone marrow (BM) dendritic cells (G-BMDCs) can expand Foxp3(+) regulatory T-cells (Tregs) through a TCR-independent, but IL-2 dependent mechanism that required OX40L/OX40 interaction. While some reports have shown suppression of autoimmunity upon treatment with an OX40 agonist, others have shown exacerbation of autoimmune disease instead. To better understand the basis for these differing outcomes, we compared the effects of OX40L treatment in 6-week-old pre-diabetic and 12-week-old near diabetic NOD mice. Upon treatment with OX40L, 6-week-old NOD mice remained normoglycemic and showed a significant increase in Tregs in their spleen and lymph nodes, while 12-week-old NOD mice very rapidly developed hyperglycemia and failed to show Treg increase in spleen or LN. Interestingly, OX40L treatment increased Tregs in the thymus of both age groups. However, it induced Foxp3(+)CD103(+)CD38(-) stable-phenotype Tregs in the thymus and reduced the frequency of autoreactive Teff cells in 6-week-old mice; while it induced Foxp3(+)CD103(-)CD38(+) labile-phenotype Tregs in the thymus and increased autoreactive CD4(+) T cells in the periphery of 12-week-old mice. This increase in autoreactive CD4(+) T cells was likely due to either a poor suppressive function or conversion of labile Tregs into Teff cells. Using ex vivo cultures, we found that the reduction in Treg numbers in 12-week-old mice was likely due to IL-2 deficit, and their numbers could be increased upon addition of exogenous IL-2. The observed divergent effects of OX40L treatment were likely due to differences in the ability of 6- and 12-week-old NOD mice to produce IL-2.

Systemic delivery of chTNT-3/CpG immunoconjugates for immunotherapy in murine solid tumor models

CpG oligodeoxynucleotides (CpG) potently activate the immune system by mimicking microbial DNA. Conjugation of CpG to chTNT-3, an antibody targeting the necrotic centers of tumors, enabled CpG to accumulate in tumors after systemic delivery, where it can activate the immune system in the presence of tumor antigens. CpG chemically conjugated to chTNT-3 (chTNT-3/CpG) were compared to free CpG in their ability to stimulate the immune system in vitro and reduce tumor burden in vivo. In subcutaneous Colon 26 adenocarcinoma and B16-F10 melanoma models in BALB/c and C57BL/6 mice, respectively, chTNT-3/CpG, free CpG, or several different control constructs were administered systemically. Intraperitoneal injections of chTNT-3/CpG delayed tumor growth and improved survival and were comparable to intratumorally administered CpG. Compared to saline-treated mice, chTNT-3/CpG-treated mice had smaller average tumor volumes by as much as 72% in Colon 26-bearing mice and 79% in B16-bearing mice. Systemically delivered free CpG and CpG conjugated to an isotype control antibody did not reduce tumor burden or improve survival. In this study, chTNT-3/CpG retained immunostimulatory activity of the CpG moiety and enabled delivery to tumors. Because systemically administered CpG rapidly clear the body and do not accumulate into tumors, chTNT-3/CpG provide a solution to the limitations observed in preclinical and clinical trials.

Circulating Myeloid-Derived Suppressor Cells Predict Differentiated Thyroid Cancer Diagnosis and Extent

BACKGROUND

Establishing the preoperative diagnosis and long-term prognosis of differentiated thyroid cancer (DTC) remain challenging in some patients. Myeloid-derived suppressor cells (MDSC) are tumor-induced cells mediating immune tolerance that are detectable in the peripheral blood of cancer patients. The authors previously developed a novel clinical assay to detect the phenotypes of two human MDSC subsets in peripheral blood, and hypothesize that higher MDSC levels measured by this assay correlate positively with both malignancy and worse patient outcomes.

METHODS

A prospective observational pilot study was performed of patients undergoing thyroidectomy for a solitary thyroid nodule. The presence of a thyroid nodule >1 cm was confirmed sonographically, and fine-needle aspiration biopsy performed prior to surgery in all cases. Peripheral blood collected preoperatively was analyzed using a novel flow cytometry-based immunoassay to detect and quantify two subsets of human MDSC. Circulating MDSC levels were compared by histopathologic diagnosis, stage, and presence of persistent disease after treatment.

RESULTS

Of 50 patients included in this study, MDSC measurement was successful in 47 (94%). One patient was found to have a concurrent cancer, leaving 46 patients for primary analysis. The cytologic diagnoses were benign in five (10.8%), atypia or follicular lesion of undetermined significance in five (10.8%), suspicious for follicular neoplasm in five (10.8%), suspicious for malignant in three (6.5%), and malignant in 28 (60.1%) of the 46 nodules. Final histopathology was benign in 11 (24%) and DTC in 35 (76%), encompassing 34 PTC cases and one follicular thyroid carcinoma. Mean percentages of CD11b(+)HLA-DR(low)HIF1a(+) MDSC (CD11b(+)MDSC) were 14.0 ± 6.2% and 7.9 ± 3.6% in DTC versus benign nodules, respectively (p < 0.005). A cutoff of 12% yielded a specificity of 0.91, a sensitivity of 0.72, and a likelihood ratio of 7.9. Mean CD11b(+)MDSC levels increased linearly with higher TNM stage (p < 0.01), and were 19.4 ± 5.4 in patients with persistent cancer after surgery compared with 13.2 ± 6.8 in those without evidence of disease (p < 0.05).

CONCLUSION

MDSC measurement using this flow cytometry-based assay represents a novel approach for preoperatively assessing malignancy risk and cancer extent in patients with thyroid nodules. While further validation is needed, these data suggest that MDSC assessment may serve as a useful adjunct when cytology is indeterminate, and predict tumor stage and recurrence risk in cases of thyroid cancer.

Monomeric annexin A2 is an oxygen-regulated toll-like receptor 2 ligand and adjuvant

BACKGROUND

Annexin A2 (ANXA2) is a pleiotropic, calcium-dependent, phospholipid-binding protein with a broad tissue distribution. It can be intracellular, membrane-bound, or secreted, and it exists as a monomer or heterotetramer. The secreted ANXA2 heterotetramer signals human and murine macrophages to produce IL-1, IL-6, and TNF-α through TLR4/MyD88- and TRIF-dependent pathways.

METHODS

GL261 glioma cells were cultured in 5 % or 20 % O2. Monomeric ANXA2 (ANXA2m) was identified as a TLR2-binding protein enriched in 5 % O2 by mass spectrometry. Purified ANXA2m and ANXA2-derived peptides were added to TLR2-expressing reporter cells and immature dendritic cells (DCs) cells in vitro. ANXA2m was then mixed with chicken ovalbumin (OVA) for vaccination of TLR2 (+/+) and TLR2 (-/-) mice for subsequent quantification of antigen-specific CD8(+) T cell responses. The TLR2-binding region of ANXA2m was determined using various peptides derived from the ANXA2 amino terminus on TLR2 reporter cells and in vaccinated mice.

RESULTS

ANXA2m is overexpressed by murine glioblastoma GL261 cells grown under 5 % O2, but not atmospheric 20 % O2, and acts as an adjuvant by inducing murine and human DC maturation through TLR2. ANXA2m upregulates CD80 and CD86 expression, enhances antigen cross-presentation, and induces the secretion of IL-12p70, TNF-α, and IFN-γ. The amino-terminal 15 amino acids of ANXA2m are necessary and sufficient for TLR2 binding and DC activation.

CONCLUSION

This novel finding adds to the known functions of ANXA2 and suggests ways to exploit it as a vaccine adjuvant. ANXA2-antigen fusion peptides could be developed for patients as "off-the-shelf" agents containing common tumor antigens. Alternatively, they could be "personalized" and synthesized after tumor sequencing to identify immunogenic tumor-specific neo-antigens. As the amino terminal 15 amino acids of ANXA2 are required to stimulate TLR2 activity, a fusion peptide could be as short as 30 amino acids if one or two CD8 T cell epitopes are fused to the ANXA2 amino terminal portion. Future work will address the efficacy of ANXA2 peptide fusions alone and in combination with established TLR agonists to induce synergy in preclinical models of glioma as observed in other vaccines.

Phase 1 Dose-Escalation Study with LEC/chTNT-3 and Toceranib Phosphate (Palladia®) in Dogs with Spontaneous Malignancies

OBJECTIVES

LEC chemokine promotes TH1 responses and recruits immune cells to inflammatory sites. By linking LEC to an antibody targeting tumor necrosis, LEC/chTNT-3 can be used for the immunotherapeutic treatment of tumors. The primary objective of this study was to determine the safety profile of LEC/chTNT-3 and toceranib phosphate (Palladia^®) combination therapy in dogs with spontaneous malignancies. Secondary purpose was to determine objective responses to treatment.

METHODS

Twenty-three dogs with cancer were enrolled, covering nine different malignancies. In this dose escalation study, dogs received LEC/chTNT-3 for five days, and toceranib every 48 hours for the remainder of the study. Dogs received physical exams, chemistry panel, urinalysis, and complete blood counts on days 0, 10, 28 of the study, and every 6-8 weeks thereafter.

RESULTS

Lethargy was noted in 13% dogs. There were no statistical differences in the prevalence of anorexia, diarrhea, thrombocytopenia, renal toxicity, or hepatic toxicity before or during the study. There were trends in increases in the prevalence of vomiting, lymphopenia, and neutropenia (all grade 2 or lower, p=0.07) over the initial 28 days of the study. By day 28, 10% of dogs had partial responses, 58% had stable disease, and 32% had progressive disease.

CONCLUSIONS

LEC/chTNT-3 and toceranib were well tolerated. This combination therapy showed some biological activity against a variety of cancers at a low dose and short duration of LEC/chTNT-3 administration.

MHC class I loss is a frequent mechanism of immune escape in papillary thyroid cancer that is reversed by interferon and selumetinib treatment in vitro

PURPOSE

To evaluate MHC class I expression on papillary thyroid cancer (PTC) and analyze changes in MHC expression and associated immune activation with current and experimental treatments for thyroid cancer using in vitro PTC cell lines.

EXPERIMENTAL DESIGN

MHC class I expression and assessment of tumor-infiltrating leukocyte populations were evaluated by immunohistochemistry. PTC cell lines were analyzed for HLA-ABC expression by flow cytometry following tyrosine kinase inhibitor, IFNα or IFNγ, or radiation treatment. Functional changes in antigenicity were assessed by coculture of allogeneic donor peripheral blood leukocytes (PBL) with pretreated or untreated PTC cell lines and measurement of T-cell activation and cytokine production.

RESULTS

Both MHC class I and β2-microglobulin expression was reduced or absent in 76% of PTC specimens and was associated with reduced tumor-infiltrating immune cells, including effector (CD3(+), CD8(+), CD16(+)) and suppressor (FoxP3(+)) populations. Treatment of PTC cell lines with the MEK1/2 inhibitor selumetinib or IFN increased HLA-ABC expression. This phenotypic change was associated with increased T-cell activation (%CD25(+) of CD3(+)) and IL2 production by PBL cocultured with treated PTC cell lines. Additive effects were seen with combination selumetinib and IFN treatment.

CONCLUSIONS

MHC class I expression loss is frequent in human PTC specimens and represents a significant mechanism of immune escape. Increased antigenicity following selumetinib and IFN treatment warrants further study for immunotherapy of progressive PTC.

BRAF V600E in papillary thyroid carcinoma is associated with increased programmed death ligand 1 expression and suppressive immune cell infiltration

BACKGROUND

There remain a small number of patients with papillary thyroid cancer (PTC) who suffer recurrence, metastases, or death. While mutation of the BRAF gene, corresponding to the constitutively active BRAF(V600E) protein, has been associated with worse clinical outcomes in thyroid cancer, the reasons underlying this observation are presently unknown. Disruption of endogenous host immune surveillance and promotion of tumor immune escape is one mechanism by which BRAF(V600E) tumors may achieve more aggressive behavior. This study evaluated the relationship between BRAF(V600E) status and known strategies of tumor-mediated immune suppression.

METHODS

Tissue sections of PTC tumors from 33 patients were evaluated by immunohistochemistry for tumor-expressed suppressive ligands and enzymes and effector and suppressor populations of tumor-infiltrating immune cells. Presence of BRAF(V600E) was evaluated by direct DNA sequencing of PTC specimens and the results correlated with tumor-expressed molecules and tumor-infiltrating immune cell populations, as well as patient characteristics and pathologic findings.

RESULTS

BRAF(V600E) tumors more often express high levels of immunosuppressive ligands programmed death ligand 1 (53% vs. 12.5%) and human leukocyte antigen G (41% vs. 12.5%) compared to BRAF wild-type tumors. There was no association between indoleamine 2,3-dioxygenase 1 expression and BRAF(V600E) status. Furthermore, BRAF(V600E) tumors demonstrate both lower CD8(+) effector to FoxP3(+) regulatory T cell, and CD68(+) pan-macrophage to CD163(+) M2 macrophage ratios, indicating relative increases in suppressive T cell and macrophage components, respectively.

CONCLUSIONS

Overall, BRAF(V600E) PTC tumors display a broadly immunosuppressive profile and evidence of disturbed host tumor immune surveillance that may contribute to the poorer outcomes observed in this subset of patients with thyroid cancer.

Treatment of experimental pancreatic cancer with 213-Bismuth-labeled chimeric antibody to single-strand DNA

BACKGROUND

Novel approaches to treatment of pancreatic cancer (PCa) are urgently needed. A chimeric monoclonal antibody (mAb) chTNT3 binds to single-strand DNA (ssDNA) and RNA released from the non-viable cells in fast growing tumors. Here the authors investigated whether radioimmunotherapy (RIT) using chTNT3 mAb radiolabeled with 213-Bismuth ((213)Bi) could be effective in treatment of experimental PCa.

METHODS

Two human PCa cell lines, Panc1 and MiaPaCa-2, were used for in vitro experiments. The xenografts in mice were established using MiaPaCa-2 cells. Therapy compared (213)Bi-chTNT3 (700 μCi) to gemcitabine or cisplatin, untreated controls and 'cold' chTNT3.

RESULTS

RIT abrogated the tumors growth while tumors in control groups grew aggressively. Chemotherapy was less effective than RIT and toxic to mice while RIT did not have any side effects.

CONCLUSIONS

RIT with (213)Bi-chTNT3 was safe and effective in the treatment of experimental PCa in comparison with chemotherapy. This makes α-RIT targeting ssDNA a promising modality for further development.

A hybrid protein-polymer nanoworm potentiates apoptosis better than a monoclonal antibody

B-cell lymphomas continue to occur with a high incidence. The chimeric antibody known as Rituximab (Rituxan) has become a vital therapy for these patients. Rituximab induces cell death via binding and clustering of the CD20 receptor by Fcγ expressing effector cells. Because of the limited mobility of effector cells, it may be advantageous to cluster CD20 directly using multivalent nanostructures. To explore this strategy, this manuscript introduces a nanoparticle that assembles from a fusion between a single chain antibody and a soluble protein polymer. These hybrid proteins express in Escherichia coli and do not require bioconjugation between the antibody and a substrate. Surprisingly a fusion between an anti-CD20 single chain antibody and a soluble protein polymer assemble worm-like nanostructures, which were characterized using light scattering and cryogenic transmission electron microscopy. These nanoworms competitively bind CD20 on two B-cell lymphoma cell lines, exhibit concentration-dependent induction of apoptosis, and induce apoptosis better than Rituximab alone. Similar activity was observed in vivo using a non-Hodgkin lymphoma xenograft model. In comparison to Rituximab, systemic nanoworms significantly slowed tumor growth. These findings suggest that hybrid nanoworms targeted at CD20 may be useful treatments for B-cell related malignancies. Because of the ubiquity of antibody therapeutics, related nanoworms may have uses against other molecular targets.