Proteomic and Metabolomic Profiles of T Cell-Derived Exosomes Isolated from Human Plasma

Exosomes that are released by T cells are key messengers involved in immune regulation. However, the molecular profiling of these vesicles, which is necessary for understanding their functions, requires their isolation from a very heterogeneous mixture of extracellular vesicles that are present in the human plasma. It has been shown that exosomes that are produced by T cells could be isolated from plasma by immune capture using antibodies that target the CD3 antigen, which is a key component of the TCR complex that is present in all T lymphocytes. Here, we demonstrate that CD3(+) exosomes that are isolated from plasma can be used for high-throughput molecular profiling using proteomics and metabolomics tools. This profiling allowed for the identification of proteins and metabolites that differentiated the CD3(+) from the CD3(-) exosome fractions that were present in the plasma of healthy donors. Importantly, the proteins and metabolites that accumulated in the CD3(+) vesicles reflected the known molecular features of T lymphocytes. Hence, CD3(+) exosomes that are isolated from human plasma by immune capture could serve as a "T cell biopsy".

Real world risk of infusion reactions and effectiveness of front-line obinutuzumab plus chlorambucil compared with other frontline treatments for chronic lymphocytic leukemia

Background

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in North America. Previous studies have shown improved progression free survival (PFS) and response rates in unfit patients treated with obinutuzumab compared to other regimens. The aim of this study was to evaluate the obinutuzumab-chlorambucil regimen in the context of historical treatments and first-dose infusion reactions at CancerCare Manitoba (CCMB).

Methods

A retrospective chart review was conducted for patients treated with obinutuzumab from January 1, 2014 to December 31, 2017 at CCMB. A minimum data set was extracted for patients treated with other front-line therapies. Descriptive statistics were used to evaluate patient demographics, toxicity, duration and dosing of obinutuzumab treatment. Kaplan–Meier curves were used to evaluate time-to-next-treatment (TTNT), overall survival (OS) and PFS for patients treated with obinutuzumab. A multivariable logistic regression model was used to investigate associations between infusion related reactions (IRRs) and age at treatment, pre-treatment lymphocyte count, cumulative illness rating scale (CIRS) and receipt of prior chemotherapy.

Results

Forty seven percent of patients receiving frontline therapy received chlorambucil and obinutuzumab. Sixty-seven patients were treated with obinutuzumab and consisted of 36 males (53.7%) and 31 females (46.3%) with 29 patients (43.3%) over age 75 years. Rates of grade 3 and 4 obinutuzumab IRRs were lower (6%) compared to the CLL11 clinical trial (20%) due to local practices including slower infusion rates and using chlorambucil before starting obinutuzumab treatment. Many patients had difficulty tolerating the full dosage of chlorambucil. Only 26 patients (38.8%) had their dose of chlorambucil escalated to the full dose of 0.5 mg/kg. In addition, only 18 patients (26.9%) received all doses of obinutuzumab and all 12 doses of chlorambucil.

Conclusions

In summary, first dose infusion reactions with obinutuzumab can be markedly reduced by using chlorambucil to decrease the lymphocyte count before obinutuzumab and by using a very slow initial obinutuzumab infusion rate. Modifications in chlorambucil dosing and obinutuzumab administration can improve tolerance without significant loss in efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09256-2.

Signaling of Tumor-Derived sEV Impacts Melanoma Progression

Small extracellular vesicles (sEV or exosomes) are nanovesicles (30–150 nm) released both in vivo and in vitro by most cell types. Tumor cells produce sEV called TEX and disperse them throughout all body fluids. TEX contain a cargo of proteins, lipids, and RNA that is similar but not identical to that of the “parent” producer cell (i.e., the cargo of exosomes released by melanoma cells is similar but not identical to exosomes released by melanocytes), possibly due to selective endosomal packaging. TEX and their role in cancer biology have been intensively investigated largely due to the possibility that TEX might serve as key component of a “liquid tumor biopsy.” TEX are also involved in the crosstalk between cancer and immune cells and play a key role in the suppression of anti-tumor immune responses, thus contributing to the tumor progression. Most of the available information about the TEX molecular composition and functions has been gained using sEV isolated from supernatants of cancer cell lines. However, newer data linking plasma levels of TEX with cancer progression have focused attention on TEX in the patients’ peripheral circulation as potential biomarkers of cancer diagnosis, development, activity, and response to therapy. Here, we consider the molecular cargo and functions of TEX as potential biomarkers of one of the most fatal malignancies—melanoma. Studies of TEX in plasma of patients with melanoma offer the possibility of an in-depth understanding of the melanoma biology and response to immune therapies. This review features melanoma cell-derived exosomes (MTEX) with special emphasis on exosome-mediated signaling between melanoma cells and the host immune system.

Abstract B58: Detection of ESR1 gene fusions in breast cancer cell-derived exosomal RNA

Background: Estrogen receptor-positive (ER+) breast cancer is often intractable due to endocrine therapy resistance. Although ER basepair hotspot mutations have been well characterized in ~20-30% of endocrine-resistant disease, accumulating evidence from our group and others suggests that other genetic alterations such as ER fusions (e.g., ESR1-DAB2) could also play a role. As an important component of liquid biopsies, exosomes have recently gained much attention in the field of clinical oncology. It is well established that some species of RNA, typically microRNA and mRNA, are packaged into these small membrane-enclosed structures, which could potentially serve as a noninvasive biomarker to constantly and comprehensively monitor tumor progression and tumor cell evolution. We tested whether ESR1 fusions could be detected in exosomal RNA (exoRNA) produced by breast cancer cell lines.

Methods: Multiple methods were used to characterize exosomes isolated from cell culture media: 1) Nanoparticle tracking analysis (NTA) confirmed concentration and size of exosomes, 2) immunoblotting identified protein markers that are enriched or lacking in exosomes, 3) transmission electron microscopy validated the size and shape of exosomes. During exoRNA extraction, DNA contamination was removed by DNase treatment. Fusion-specific regions in exoRNA were amplified by standard PCR.

Results: We used breast cancer cell lines stably infected with cDNA encoding ESR1 fusions ESR1-DAB2 and ESR1-SOX9. NTA shows that our isolated exosomes had a size ranging from 30-150 nm, with the peak at 80 nm. Immunoblotting showed TSG101 and CD81 as positive markers of our exosomes, while Grp94 was negative. By RT-PCR, we identified a fusion-specific region amplified for both ESR1-SOX9 and ESR1-LPP from exoRNA for the fusion cell lines.

Conclusions: Collectively, these data indicate that multiple ESR1 fusions are detectable in breast cancer cell line-derived exoRNA.

Citation Format: Tiantong Liu, Jagmohan Hooda, Nils Ludwig, Theresa Whiteside, Jennifer M. Atkinson, Steffi Oesterreich, Adrian Lee. Detection of ESR1 gene fusions in breast cancer cell-derived exosomal RNA [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B58.

Isolation and characterization of exosomes from IDH mutant gliomas

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Background: Mutations in the metabolic enzyme isocitrate dehydrogenase 1 (IDH1) are found in > 70% of intermediate grade gliomas. Gain-of-function mutations in IDH1 promote diffuse glioma formation through epigenetic reprogramming of a number of genes, including immune-related genes. Tumor-derived exosomes (TEX) accumulate in the tumor microenvironment (TME) and in body fluids of patients. TEX serve as a communication system between tumor and normal cells. Circulating TEX carry a complex molecular and genetic cargo and interfere with functions of immune cells. This study characterizes TEX produced by IDH mutant glioma spheres and TEX from plasma of patients with IDH mutant gliomas. Methods: TEX produced by patient-derived IDH1(mut) or IDH1(wt) glioma spheres or TEX in patient’s plasma were isolated by mini size exclusion chromatography (mini-SEC). TEX morphology, size, numbers and molecular profile were characterized and the crossing of the blood-brain barrier (BBB) and biodistribution was investigated by in vivo imaging of TEX. Interactions of TEX with endothelial cells, astrocytes and immune cells were demonstrated by confocal microscopy. Results: TEX isolated from supernatants of IDH1(mut) or IDH1(wt) glioma spheres by mini-SEC carried TSG101 and showed the typical size and vesicular morphology of exosomes. BCA protein assays and qNano analysis revealed an elevated exosome production by IDH mutant cells ( p< 0.01). TEX carried immunosuppressive proteins (FasL, CTLA-4 and TRAIL) and IDH mutant exosomes carried higher levels of these proteins and of adenosine pathway components CD39 and CD73. Labeled TEX injected in the white matter of mice crossed the BBB and were detectable in distant organs 24h after injection. TEX were rapidly internalized by endothelial cells and astrocytes, but not by T cells, which interacted with TEX by surface signaling. These results were confirmed by investigating TEX isolated from glioma patient’s plasma. Conclusions: The data suggest that TEX play an important role in IDH mutant gliomas and drive tumor progression in part by inducing suppression of immune cells. Future efforts will focus on characterizing immunosuppressive effects of TEX derived from IDH mutant cells vs gliomas without IDH mutations.

Clinical significance of PD-L1 levels in plasma-derived exosomes in head and neck cancer

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Background: Despite the broad spectrum of available therapies, HNSCC patients have poor outcome due to locoregional recurrence. Mechanisms responsible for immune suppression include activities of checkpoint receptors/ligands. HNSCCs with high expression levels of PD-L1 have especially poor outcome. Thus, PD-1 and PD-L1 inhibitors show potential as anticancer strategies. However, many patients with PD-L1+ HNSCC don’t benefit from checkpoint inhibitor therapy, suggesting that PDL-1 expression on tumors is not the only factor predictive of response. Tumor derived exosomes carry numerous immunosuppressive molecules and deliver them to recipient immune cells. We have demonstrated that elevated levels of circulating immunosuppressive exosomes play a key role in immune suppression and disease progression. Here, we show that surface PD-L1 on exosomes is responsible for these effects. Methods: Exosomes were isolated from plasma of 40 HNSCC patients by mini size exclusion chromatography, captured on beads using anti-CD63 Abs, stained for PD-1 and PD-L1 and analyzed by flow cytometry. Percentages of PD-L1+ and PD-1+ exosome/bead complexes were correlated with clinicopathological data. PD-L1high or PD-L1low exosomes were incubated with activated human CD8 T-cells ± PD-1 inhibitor and CD69 expression levels on T-cells were measured. Patients’ plasma was tested for soluble PD-L1 by ELISA. Results: The PD-L1 surface expression on exosomes correlated with patient’s disease activity, UICC stage and lymph node status with p values ranging from 0.0008-0.013. In contrast, plasma PD-L1 levels didn't correlate with any parameters. Exosome PD-1 levels were not informative. T-cell activation was inhibited (p < 0.03) by co-incubation with PD-L1high but not PD-L1low exosomes. This inhibition was reversed by adding a PD-1 inhibitor to T-cells prior to their incubation with exosomes. Conclusions: We show that PD-L1 levels on exosomes, but not plasma levels, correlated with clinicopathological data in HNSCC patients. Blocking of PD-L1+ exosomes signaling to PD-1+ T-cells with anti-PD-1 Ab attenuated immune suppression. Altogether, PD-L1+ exosomes serve as useful metrics of disease and immune activity in HNSCC patients.

Isolation of Exosomes for the Purpose of Protein Cargo Analysis with the Use of Mass Spectrometry

Exosomes are intercellular messengers with a high potential for diagnostic and therapeutic utility. It is believed that exosomes present in body fluids are responsible for providing signals which inhibit immune cells, interfere with antitumor immunity, and thus influence the response to treatment and its effect. One of the most interesting issues in exosome studies is proper addressing of their cargo composed of nucleic acids and proteins. Effective and selective isolation of extracellular vesicles and identification of proteins present in exosomes has turned out to be a challenging aspect of their exploration. Here we propose a novel approach that is based on isolation of exosomes by mini-size-exclusion chromatography which allows efficient, rapid, and reliable isolation of morphologically intact and functionally active exosomes without the need of ultracentrifugation. The purpose of this chapter is to describe a simple and high-throughput method to isolate, purify, and identify exosomal proteins using a mass spectrometry approach. The proposed protocol compiles the expertise of two research groups specialized in exosome research and in mass spectrometry-based proteomics. The protocol combines differential centrifugation followed by ultrafiltration, centrifugation-based filtration, and gel filtration on Sepharose 2B in order to obtain exosomal fractions characterized by only low contamination with albumin.

Expression and clinical significance of MAGE and NY-ESO-1 cancer-testis antigens in adenoid cystic carcinoma of the head and neck

BACKGROUND

Adenoid cystic carcinoma (ACC) of the head and neck is a rare but highly malignant tumor. Cancer-testis antigens (CTAs) represent an immunogenic family of cancer-specific proteins and thus represent an attractive target for immunotherapy.

METHODS

Eighty-four cases of ACC were identified, the CTAs pan-Melanoma antigen (pan-MAGE; M3H67) and New York esophageal squamous cell carcinoma (NY-ESO-1; E978) were detected immunohistochemically (IHC) and correlated with clinical data.

RESULTS

Expression of NY-ESO-1 was found in 48 of 84 patients (57.1%) and of pan-MAGE in 28 of 84 patients (31.2%). Median overall survival (OS) in NY-ESO-1 positive versus negative patients was 130.8 and 282.0 months (p = .223), respectively. OS in pan-MAGE positive versus negative patients was 105.3 and 190.5 months, respectively (p = .096). Patients expressing both NY-ESO-1 and pan-MAGE simultaneously had significantly reduced OS with a median of 90.5 months compared with 282.0 months in negative patients (p = .047).

CONCLUSION

A significant fraction of patients with ACC show expression of the CTAs NY-ESO-1 and/or pan-MAGE with promising immunotherapeutic implications. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1008-1016, 2016.

Expression of Submaxillary Gland Androgen-regulated Protein 3A (SMR3A) in Adenoid Cystic Carcinoma of the Head and Neck

BACKGROUND

Adenoid cystic carcinoma of the head and neck (ACC) is a rare tumor entity which originates from the salivary glands. The prognosis remains poor, as the tumor tends to exhibit perineural invasion and frequently develops distant metastases. The submaxillary gland androgen-regulated protein 3A (SMR3A) belongs to a gene family producing opiorphin homologs and is physiologically secreted by salivary glands. Expression of SMR3A has been identified as an unfavorable risk factor in survival of patients with squamous cell carcinoma in the head and neck, but its value as a prognostic biomarker for ACC has not been addressed.

MATERIALS AND METHODS

Tissue sections from primary ACC (n=86) and healthy glandular tissue as reference, were stained by immunohistochemistry. SMR3A expression levels were correlated with clinical and pathological features, including overall survival.

RESULTS

All patients had undergone surgery and 67 received adjuvant radiotherapy. The median disease-free survival (DFS) was 37 months and the median overall survival (OS) was 75 months. Prominent SMR3A expression in tumor cells was found in 24 of 86 patients (27,9%), and was inversely correlated with a male gender (p=0.009). There was no significant correlation between SMR3A expression and DFS, metastasis-free survival or OS.

CONCLUSION

Our data demonstrate for the first time decreased levels of SMR3A in ACC compared to normal glandular tissue. These data suggest a context-dependent regulation of SMR3A expression in the pathogenesis of distinct subtypes of head and neck tumors, and support the assumption that detection of SMR3A expression serves as a surrogate for aberrant differentiation into mucosal- or glandular-like cells in ACC and head and neck squamous cell carcinoma.

Tumor-derived exosomes differentially modulate the adenosine pathway in human resting vs activated regulatory T cells (Treg) (TUM4P.927)

Tumor-derived exosomes (TEX) suppress functions of human immune cells, while up-regulating functions of others. Here, we show that TEX isolated from supernatants of human cultured tumor cells or plasma of cancer patients differentially modify gene and protein expression of CD39, CD73 and adenosine receptors (ADORs) in Treg, influencing production of suppressive nucleosides. Resting or pre-activated (anti-CD3/CD28 Abs) CD4+CD39+ Treg were co-incubated overnight with TEX. Cellular mRNA was analyzed by qRT-PCR for expression of CD39, CD73, A1R, A2aR, A2bR and A3R genes. Protein expression was studied by flow cytometry and western blots. Nucleoside production by Treg ± TEX in the presence of 20µM ATP was measured by mass spectrometry. In resting Treg + TEX, mRNA expression of CD39/CD73 and ADORs was reduced relative to no TEX baseline (&gt;1 log) except for A1R mRNA expression which was elevated (&gt; 3 logs). CD39 protein expression was up-regulated, suggesting enhanced translation and signaling via A1R. Treg + TEX + ATP produced inosine only (7900ng/mL) and no 5’-AMP or ADO. In activated Treg +TEX, CD39/CD73 mRNA expression and protein levels were elevated (p&lt; 0.05) as was mRNA expression for all ADORs, especially A2aR, and ADO was produced. Thus, TEX differentially regulated gene expression and protein levels of the ADO pathway components in resting vs activated Treg. The TEX-induced shift from inosine to ADO production implies changes in Treg-mediated immunosuppression.

Plasma-derived exosomes mediate immune suppression and serve as a biomarker of response to chemotherapy in Acute Myeloid Leukaemia (AML) (TUM7P.945)

Exosomes are virus-sized (30-100nm) vesicles formed within endocytic compartment and released into extracellular space. While all cells are capable of releasing exosomes under physiologic conditions, tumor cells are avid exosome producers. We have previously shown that plasma of AML patients at diagnosis contain high levels of exosomes relative to normal controls’ plasma (NC). AML exosomes carry various immunosuppressive molecules, including TGF-β1 related to NK-cell dysfunction in AML. Here we show that molecular content of exosomes isolated from patients’ plasma before, during and after chemotherapy (CT) reflects disease status. Thus, exosomes present in patients’ circulation carry biomarkers that can be useful in evaluating responses to therapy. AML exosomes carry different forms of TGF-β1 (pro-peptide, latency-associated peptide or active form) in different proportions. Only TGF-β1 pro-peptide was seen in exosomes obtained from NC or patients in remission. While TGF-β1 levels tracked protein levels in exosomes, elevated TGF-β1 levels discriminated better between patients receiving CT whose leukemia was likely to recur. In addition, co-incubation of normal NK cells with exosomes carrying active TGF-β1 resulted in down-regulation of NKG2D expression. In conclusion, elevations in exosomal protein and/or TGF-β1 levels during CT may reflect an incomplete response to CT and suggest the presence of residual disease in patients considered to have achieved complete remission.

CTLA-4+ regulatory T cells are increased in cetuximab treated head and neck cancer patients, suppress NK cell cytotoxicity and correlate with poor prognosis (TUM2P.916)

The EGFR-targeted antibody, cetuximab, is clinically effective against head and neck cancer (HNC) but only in 15 - 20% of patients. We hypothesized that regulatory T cells may have functional and clinical impact antitumor immunity induced in cetuximab-treated patients. Indeed, Treg frequency and expression of CTLA-4, CD39, and surface TGF-β were significantly increased after cetuximab-based therapy. These Treg were inversely associated with functional activity of intratumoral NK cells and with clinical outcome in cetuximab-treated HNC patients. Importantly, NK cells selectively eliminated intratumoral Treg in the presence of anti-CTLA mAb (ipilimumab), which overcame the Treg suppressive activity on cetuximab-mediated ADCC. These results suggest that differences in Treg-mediated suppression may play a role in the clinical response to cetuximab therapy, and that efficacy of cetuximab therapy could be enhanced by adding ipilimumab to eliminate Treg, thus promoting anti-tumor immunity.

Pathologic and gene expression features of metastatic melanomas to the brain

BACKGROUND

The prognosis of metastatic melanomas to the brain (MBM) is variable with prolonged survival in a subset. It is unclear whether MBM differ from extracranial metastases (EcM) and primary melanomas (PrM).

METHODS

To study the biology of MBM, histopathologic analysis of tumor blocks from patients' craniotomy samples and whole-genome expression profiling (WGEP) with confirmatory immunohistochemistry were performed.

RESULTS

High mononuclear infiltrate and low intratumoral hemorrhage were associated with prolonged overall survival (OS). Pathway analysis of WGEP data from 29 such craniotomy tumor blocks demonstrated that several immune-related BioCarta gene sets were associated with prolonged OS. WGEP analysis of MBM in comparison with same-patient EcM and PrM showed that MBM and EcM were similar, but both differ significantly from PrM. Immunohistochemical analysis revealed that peritumoral CD3⁺ and CD8⁺ cells were associated with prolonged OS.

CONCLUSIONS

MBMs are more similar to EcM compared with PrM. Immune infiltrate is a favorable prognostic factor for MBM.

Association of high T-cell immune infiltrate and low hemorrhage in melanoma brain metastases (MBMs) with prolonged survival

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Background: Despite the poor prognosis of patients (pts) with MBM several pts have prolonged survival. We hypothesized that the heterogeneity of BrMM is determined by differences in melanoma biology and its brain microenvironment. Methods: We identified pts who have undergone craniotomy for MBMs. Evaluation entailed complete clinical information, acquisition of archived melanoma brain metastases, histopathologic analysis of hematoxylin and eosin-stained sections (n=101), whole genome expression profiling (WGEP, Illumina DASL) in 29 archived tissues. Results were validated by immunohistochemistry (IHC) or in situ hybridization (ISH). Results: In univariate analysis (log-rank) factors significantly associated with prolonged survival were high immune infiltrate (HII) plus low hemorrhage (hazard ratio, HR, 2.71, p<0.001), present melanin (1.67, p=0.03), and recursive partitioning analysis (RPA) class 1 (0.37, p<0.0001). No association between HII and use of immunotherapy prior to craniotomy was noted. Only RPA class 1 (p=0.029) and HII plus low hemorrhage (p=0.002) remained significant in Cox proportional hazards model analysis. Gene set analysis of WGEP data confirmed that Encarta pathways related with T-cell activation and differentiation were significantly associated with prolonged survival whereas Y branching of actin filaments, presenilin action in Notch and Wnt signaling, G-protein signaling through tubby protein, lissencephaly gene in neuronal migration and development are among the gene categories associated with worse survival. IHC and ISH analysis of tumor sections for various markers (n=40) showed that high peritumoral CD3+ (3.31, p=0.009), high peritumoral CD4+ (4.41, p=0.014), and high peritumoral CD8+ (3.02, p=0.030) are associated with prolonged survival whereas neither CD14+ nor FoxP3+ infiltrate, nor high melanoma expression of antigen presentation molecules are associated with survival. Conclusions: Our study is the first to document that high peritumoral T-cell infiltrates are associated with prolonged survival. High tumor hemorrhage, an adverse prognostic sign, reflects aggressive melanoma cells that migrate and invade in the brain.

Reverse correlation between CD39+CD25+ Treg and activated CD8+ T cells / NK cells in HIV-1- patients with low CD4 cell counts (105.48)

The role of regulatory T cells (Treg) in HIV has been studied intensely but remains unclear regarding their effect on cellular immune activation. Frequencies of CD4 and CD8 T cells, CD39+CD25+ Treg, Th17 cells, MDSC, B cells, NK cells and the activation status of T cells (CD38+HLADR+) were determined by flow cytometry in 10 healthy controls and 32 HIV-1+ patients. Immunosuppressive functions of single-cell sorted Treg were determined in the CFSE proliferation assay. Cytokine production (IL1b, 2, 4, 5, 6, 8, 10, INFg, TNFa, GM-CSF), C-reactive protein and soluble CD14 were measured in patients’ plasma by Luminex and ELISA. The absolute number of CD39+CD25+ Treg was significantly decreased in HIV-patients compared to normal controls (p=0.001). However, the frequency of Treg (p=0.04) and HLADR+CD38+CD8+ T cells (p=0.05) was increased only in patients with anti-retroviral therapy (ART). HIV+ patients with ART and low CD4+ cell count had the highest level of immune activation (p=0.04), and in this group we observed a significant negative correlation between CD39+CD25+ Treg and activated T cells (r2=0.5) as well as increased numbers of NK-cells. In ART-treated HIV+ patients with CD4+ T cell recovery, the frequency of Treg, NK cells and CD8+ T cell activation normalized. ART restores the frequency of Treg and activated T cells to normal levels. However, in patients whose CD4+ T cell count did not recover during ART, Treg frequency negatively correlated with T cell immune activation.

Two functionally-distinct subsets of CD4+CD39+ Treg in patients with HIV-1 infection (154.36)

Ectonucleotidases CD39 and CD73 are expressed on the surface of regulatory T cells (Treg) and cleave ATP to immunosuppressive adenosine. CD39 could potentially serve as a new functional marker for Treg isolation. The frequency and absolute numbers of CD4+CD39+ T cells were determined in 32 HIV+ patients and in 10 healthy donors (HD). CD4+ T cells were negatively selected by magnetic beads PBMC. CD39+ Treg cells were then isolated by biotin-conjugated anti-CD39 Abs and anti-biotin magnetic beads. T cells were phenotyped by flow cytometry for CD39+, CD73+, FOXP3+, CCR4+, CD127neg, CD49dneg, and CD121a+. CFSE-based proliferation assays and ATP hydrolysis were used to measure Treg functions. Cytokine expression in CD4+CD39+ T cells was determined by Luminex. HIV-patients on and off anti-retroviral regimen had a significantly lower absolute number of CD39+CD25+ Treg and CD39+CD25neg T cells (p&lt;0.05) than HD. The CD4+CD39+ T cell populations isolated on immunobeads contained two cell subsets: FOXP3+CD25+ Treg hydrolyzed exogenous ATP and suppressed CD4+ T cell proliferation, which was reversed by blocking ectonucleotidase activity. In contrast, the FOXP3negCD25neg T cells were CD127+CD49d+ and expressed IFNg, TNFa, and IL-10. The presence of two distinct CD4+CD39+ cell subsets in PBMC is a general phenomenon seen in normal donors, as well as patients with HIV and cancer. This suggests that phenotypic and functional plasticity characterizes the human Treg subset.

IRX-2, a novel immunotherapeutic, enhances NK cell function and protects NK cells from TGFβ-mediated inhibition. (156.14)

Background: IRX-2 is a primary biologic which has been used for therapy of head and neck cancer with promising clinical results. Since NK cell function is compromised in head and neck cancer (HNC) patients, we tested the effects of IRX-2 on human NK cells in vitro. Methods: PBMC were isolated 10 HNC patients and 10 healthy donors (HD). NK cell phenotype and function were compared before and after culture ± IRX-2 or 50 IU/ml IL-2. NK cell phenotype, signaling, cytotoxicity and cytokine production were studied by flow cytometry. Results: Cytotoxicity was impaired in HNC patients (614 LU20 vs. 2760 LU20, p&lt;0.01). Mean expression of NKG2D, NKp30 and NKp46 was significantly lower in HNC patients than in HD (p&lt;0.05). Patients’ NK cells treated with IRX-2 expressed higher levels of these receptors than those treated with IL-2 (p&lt;0.05) and showed higher cytotoxicity (3000 LU20 vs. 1300 LU20, p&lt;0.01). In the presence of TGF-β, IL-2 did not increase the expression of activating NK cell receptors while IRX-2 still upregulated NKG2D and NKp30 (p&lt;0.05). More importantly, IRX-2 protected NK cells from TGF-β- mediated impairment of cytotoxicity (p&lt;0.05), while IL-2 did not. Conclusions: IRX-2 is more effective in enhancing and protecting NK cell function of HNC patients in vitro than IL-2 alone. Our data suggest that clinical responses previously observed in HNC patients treated with IRX-2 could be, at least in part, attributed to restored NK cell function.

Developments in clinical cell therapy

Immunotherapy has become an important part of hematopoietic stem cell (HSC) transplantation and cancer therapy. Regenerative and reparative properties of somatic cell-based therapies hold tremendous promise for repairing injured tissue, preventing and reversing damage to organs, and restoring balance to compromised immune systems. The principles and practices of the diverse aspects of immune therapy for cancer, HSC transplantation and regenerative medicine have many commonalities. This meeting report summarizes a workshop sponsored by the National Heart, Lung and Blood Institute (NHLBI) and Production Assistance for Cellular Therapies (PACT), held on 23-24 April 2009 at the National Institutes of Health (NIH, USA). A series of scientific sessions and speakers highlighted key aspects of the latest scientific, clinical and technologic developments in cell therapy, involving a unique set of cell products with a special emphasis on converging concepts in these fields.

Continuous Intra-Lymphatic Dendritic Cell Infusion in Patients with Advanced Melanoma (41.51)

Continuous intralymphatic delivery of dendritic cells (DCs), using implantable lymphatic cannulas, allows to efficiently deliver "non-exhausted" DCs to draining lymph nodes without the disruption of nodal structures, and to recreate the physiologic kinetics of DC accumulation observed during physiologic immune responses.

We have completed initial feasibility and safety evaluation of semi-continuous intralymphatic infusions of antigen-loaded DCs (a total of 300,000 DCs over 4 days) in six patients with stage IIIb-IV melanoma in clinical trial UPCI 03-118. Four of the initial six patients received two four-day-long courses of the intralymphatic DC infusions, completing the protocol. Two patients did not complete the treatment for reasons unrelated to the protocol.

Already at this ultra-low dose of DCs, we have observed evidence of clinical efficacy of DC infusions in 3 of 4 patients with stage IV melanoma who completed both courses of treatment. We observed one near-complete response (currently &gt;20 months), and two disease stabilizations (10 months; and &gt; 7 months), with only one patient progressing. We have recently initiated the evaluation of "high-dose" intralymphatic infusions (total of 3 million DCs over 4 days).

Our data demonstrate the feasibility of prolonged intralymphatic delivery of biotherapeutic agents and provide preliminary indication that DCs can be clinically effective in patients with advanced cancer at the doses 100-fold lower than previously considered to be necessary.

Immunogenicity and antitumor effects of vaccination with peptide vaccine+/-granulocyte-monocyte colony-stimulating factor and/or IFN-alpha2b in advanced metastatic melanoma: Eastern Cooperative Oncology Group Phase II Trial E1696

PURPOSE

No therapy has ever shown prolongation of survival in stage IV metastatic melanoma. The association of cytokine-induced autoimmunity with improved prognosis led us to investigate the effect of multi-epitope melanoma vaccines alone and in combination with cytokines in this Eastern Cooperative Oncology Group multicenter phase II trial.

EXPERIMENTAL DESIGN

Eligible patients were required to have failed prior therapies and to be HLA-A2 positive. Three HLA class I-restricted lineage antigen epitopes were administered in a factorial 2x2 design. Peptide vaccine alone (arm A), or combined with granulocyte-monocyte colony-stimulating factor (GM-CSF; Immunex) 250 microg/d subcutaneously for 14 of 28 days each month (arm B), or combined with IFN-alpha2b (Intron A; Schering-Plough) 10 million units/m2 three times a week (arm C), or combined with both IFN-alpha2b and GM-CSF (arm D). The primary endpoint was immune response measured by enzyme-linked immunospot assay; secondary endpoints were clinical antitumor response, disease-free survival, and overall survival.

RESULTS

One hundred twenty patients enrolled and 115 patients were analyzed. Immune responses to at least one melanoma antigen were observed in 26 of 75 (35%) patients with serial samples. Neither IFN-alpha2b nor GM-CSF significantly improved immune responses. Six objective clinical responses were documented. At a median follow-up of 25.4 months, the median overall survival of patients with vaccine immune response was significantly longer than that of patients with no immune response (21.3 versus 13.4 months; P=0.046).

CONCLUSION

Immune response to vaccination correlates with prolonged survival in patients with metastatic melanoma and is not enhanced by immunomodulatory cytokines as tested in this trial.

MVA-MUC1-IL2 vaccine immunotherapy (TG4010) improves PSA doubling time in patients with prostate cancer with biochemical failure

PURPOSE

TG4010 is a recombinant MVA vector expressing the tumor-associated antigen MUC1 and IL2. We explored the effect two schedules of TG4010 on PSA in men with PSA progression.

PATIENTS AND METHODS

A randomized phase II trial was conducted in 40 patients with PSA progression. Patients had PSA doubling times less than 10 months, with no overt evidence of disease. Patients received either weekly subcutaneous injection (sc) of TG4010 10(8) pfu for 6 weeks, then one injection every 3 weeks or sc injection of TG4010 10(8) pfu every 3 weeks.

RESULTS

The primary endpoint of a 50% decrease in PSA values from baseline was not observed. Nevertheless, 13 of 40 patients had a more than two fold improvement in PSA doubling time. Ten patients had their PSA stabilized for over 8 months. Therapy was well tolerated.

CONCLUSIONS

Although the primary endpoint was not achieved, there is evidence of biologic activity of TG4010 in patients with PSA progression, further investigation in prostate cancer is warranted.

A phase I/II study of a MUC1 peptide pulsed autologous dendritic cell vaccine as adjuvant therapy in patients with resected pancreatic and biliary tumors

Pancreatic and biliary cancers are relatively resistant to chemotherapy and radiation and may therefore provide an opportunity for testing the potential of immunotherapy. MUC1 is an epithelial cell glycoprotein that is highly overexpressed and aberrantly glycosylated in many adenocarcinomas, including pancreatic tumors, providing a tumor specific antigen and target. We performed a Phase I/II clinical trial of a MUC1 peptide-loaded DC vaccine in 12 pancreatic and biliary cancer patients following resection of their primary tumors. The primary endpoints were vaccine toxicity and immunogenicity and the secondary endpoint was clinical outcome. The vaccine was well tolerated and no toxicity was observed. Three patients had pre-existing MUC1 antibody responses that remained stable post vaccination. MUC1-specific T cell responses were difficult to evaluate due to increases in activity of all CD8 and CD4 T cells following each vaccination. Prior to vaccination, patients entered onto this trial had a significantly higher percentage of FoxP3+CD4+ T cells compared to age matched healthy controls. The percentage of these cells also increased transiently following each injection, returning to baseline or below before the next injection. Vaccinated patients have been followed for over four years and four of the twelve patients are alive, all without evidence of recurrence. Study of the immune parameters in long-term survivors several years after vaccination may yield the sought after immune correlates of clinical responses that analysis of immune responses shortly after vaccination has not revealed.

Dendritic cells for active immunotherapy: optimizing design and manufacture in order to develop commercially and clinically viable products

Dendritic cell (DC) active immunotherapy is potentially efficacious in a broad array of malignant disease settings. However, challenges remain in optimizing DC-based therapy for maximum clinical efficacy within manufacturing processes that permit quality control and scale-up of consistent products. In this review we discuss the critical issues that must be addressed in order to optimize DC-based product design and manufacture, and highlight the DC based platforms currently addressing these issues. Variables in DC-based product design include the type of antigenic payload used, DC maturation steps and activation processes, and functional assays. Issues to consider in development include: (a) minimizing the invasiveness of patient biological material collection; (b) minimizing handling and manipulations of tissue at the clinical site; (c) centralized product manufacturing and standardized processing and capacity for commercial-scale production; (d) rapid product release turnaround time; (e) the ability to manufacture sufficient product from limited starting material; and (f) standardized release criteria for DC phenotype and function. Improvements in the design and manufacture of DC products have resulted in a handful of promising leads currently in clinical development.

Stress-associated changes in the steady-state expression of latent Epstein-Barr virus: implications for chronic fatigue syndrome and cancer

Antibodies to several Epstein-Barr virus (EBV)-encoded enzymes are observed in patients with different EBV-associated diseases. The reason for these antibody patterns and the role these proteins might play in the pathophysiology of disease, separate from their role in virus replication, is unknown. In this series of studies, we found that purified EBV deoxyuridine triphosphate nucleotidohydrolase (dUTPase) can inhibit the replication of human peripheral blood mononuclear cells in vitro and upregulate the production of TNF-alpha, IL-1beta, IL-6, IL-8, and IL-10. It also enhanced the ability of natural killer cells to lyse target cells. The EBV dUTPase also significantly inhibited the replication of mitogen-stimulated lymphocytes and the synthesis of IFN-gamma by cells isolated from lymph nodes and spleens obtained from mice inoculated with the protein. It also produced sickness behaviors known to be induced by some of the cytokines that were studied in the in vitro experiments. These symptoms include an increase in body temperature, a decrease in body mass and in physical activity. The data provide a new perspective on how an early nonstructural EBV-encoded protein can cause immune dysregulation and produce clinical symptoms observed in patients with chronic fatigue syndrome (CFS) separate from its role in virus replication and may serve as a new approach to help identify one of the etiological agents for CFS. The data also provide additional insight into the pathophysiology of EBV infection, inflammation, and cancer.

Phase I study of a MUC1 vaccine composed of different doses of MUC1 peptide with SB-AS2 adjuvant in resected and locally advanced pancreatic cancer

MUC1 is a glycoprotein overexpressed in tumors as a hypoglycosylated form. A vaccine composed of a 100-amino acid peptide corresponding to five 20-amino acid long repeats, and SB-AS2 adjuvant, was tested in a phase I study for safety, toxicity, and ability to elicit or boost MUC1-specific immune responses. Patients with resected or locally advanced pancreatic cancer without prior chemotherapy or radiotherapy were eligible. Escalating doses of the peptide (100, 300, 1,000, and 3,000 mug) were admixed with SB-AS2 and administered intramuscularly every 3 weeks for three doses, in cohorts of four patients. Sixteen patients were enrolled. Common adverse effects were grade 1 flu-like symptoms, tenderness, and erythema at the injection site. Delayed-type hypersensitivity (DTH) sites showed few or no T cells prevaccination (Pre V), but increased T-cell infiltration postvaccination (Post V). There was an increase in the percentage of CD8(+) T cells in the peripheral blood Post V. An increase in total MUC1-specific antibody was seen in some patients, and several patients developed IgG antibody. Two of 15 resected pancreatic cancer patients are alive and disease free at follow-up of 32 and 61 months. MUC1 100mer peptide with SB-AS2 adjuvant is a safe vaccine that induces low but detectable mucin-specific humoral and T-cell responses in some patients. No difference was seen between different peptide doses. Further evaluation is warranted to examine the effect on disease-free survival and overall survival, especially in early disease and in the absence of immunosuppressive standard therapy.

The relationship between chronic pain, immune function, depression, and health behaviors

The objectives of this study were 1) to determine the relationships between pain perceptions, immune function, depression and health behaviors and 2) to examine the effects of chronic pain on immune function using depression and health behaviors as covariates. A nonexperimental cross-sectional design was used to compare 24 chronic back pain patients with 33 asymptomatic no-pain healthy subjects. Immune function measures using natural killer (NK) cell activity, percent and numbers of NK cells, and T-cell lymphocyte proliferation with mitogens concanavalin A (ConA) and pytohemagglutinin (PHA) as well as self-report measures for depression and health behaviors were collected on all subjects. Pain perceptions showed positive significant correlations with depression (P = 0.01) and total percent of NK cells (P = 0.04). Depression and health behaviors were negatively correlated (P = 0.01). Positive associations were observed for depression and 2 PHA mitogen levels (P < 0.05). Comparison of group means, controlling for depression and health behaviors, showed that chronic pain patients' immune function, as measured by the combined NK effector to target (E:T) cell ratio levels, was significantly higher than the no-pain comparison group. Pain perceptions may have a deleterious effect on enumerative NK cell measures and depression levels. However, people with chronic pain may not experience attenuation in functional immune parameters.

A phase I trial of immunotherapy with intratumoral adenovirus-interferon-gamma (TG1041) in patients with malignant melanoma

AIMS

Interferon-gamma (IFN-gamma) has been shown to upregulate MHC class I and II expression, and to promote generation of specific antitumor immune responses. We hypothesized that intratumoral administration of an IFN-gamma gene transfer vector facilitates its enhanced local production and may activate effector cells locally. We conducted a phase I dose-escalation study of a replication-deficient adenovirus-interferon-gamma construct (TG1041) to determine safety and tolerability of intratumoral administration, in advanced or locally recurrent melanoma.

METHODS

Patients were enrolled at four successive dose levels: 10(7) infectious units (iu) (n=3), 10(8) iu (n=3), 10(9) iu (n=3), and 10(10) iu (n=2) per injection per week for 3 weeks. TG1041 was injected in the same tumor nodule weekly in each patient. Safety, toxicity, local and distant tumor responses and biologic correlates were evaluated.

RESULTS

A total of 11 patients were enrolled and received the planned three injections per cycle. One patient with stable disease received a second cycle of treatment. A maximum tolerated dose was not reached in this study. No grade 4 toxicities were observed. Two grade 3 toxicities, fever and deep venous thrombosis were observed in one patient. The most frequently reported toxicities were grade 1 pain and redness at the injected site (n=8), and grade 1 fatigue (n=5) patients. Clinical changes observed at the local injected tumor site included erythema (n=5), a minor decrease in size of the injected lesion (n=5) and significant central necrosis by histopathology (n=1). Systemic effects included stable disease in one patient. Correlative studies did not reveal evidence of immunologic activity.

CONCLUSION

Weekly intratumoral administration of TG1041 appears to be safe and well tolerated in patients with advanced melanoma.

Posttransplant adoptive immunotherapy with activated natural killer cells in patients with metastatic breast cancer

Relapse after high-dose chemotherapy is the main cause of therapeutic failure in patients with metastatic breast cancer. Adoptive immunotherapy with interleukin-2 (IL-2) plus activated natural killer cells may eliminate residual disease without excessive toxicity. The authors sought to determine if immunotherapy immediately after transplantation would affect engraftment and the toxicity associated with transplantation. Fifteen consecutive patients with metastatic breast cancer were allocated to three cohorts. Cohort 1 (five patients) received high-dose cyclophosphamide, thiotepa, and carboplatin (CTCb) followed by peripheral blood stem cell infusion and granulocyte colony-stimulating factor at 10 micrograms/kg. Cohort 2 (five patients) received in addition rhIL-2 (2 x 10(6) IU/m2/day) for 4 days intravenously via continuous infusion after peripheral blood stem cell infusion. In cohort 3 (five patients), peripheral blood stem cell transplant was followed by infusion of autologous activated NK cells and rhIL-2 (2 x 10(6) IU/m2/day) for 4 days (via continuous intravenous infusion). Generation of activated NK cells was possible in all patients in cohort 3. All patients has successful engraftment. Median time to absolute neutrophil count more than 0.5 x 10(9)/L was 8 days (range, 8 to 11 days) in cohort 1, 9 days (range, 7 to 11 days) in cohort 2, and 9 days (range, 8 to 9 days) in cohort 3. Median time until the platelet count was more than 20 x 10(9)/L was 14 days (range, 9 to 22 days) in cohort 1, 11 days (range, 6 to 14 days) in cohort 2, and 12 days (range, 11 to 21 days) in cohort 3. All patients developed neutropenic fevers, but the overall toxicity associated with the infusion of IL-2 (cohort 2) or IL-2 plus activated NK cells (cohort 3) did not differ from that observed in cohort 1. Complete responses were achieved in one patient in cohort 1, in two patients in cohort 2, and in one patient in cohort 3. In conclusion, post-transplant adoptive immunotherapy with activated NK cells plus IL-2 is feasible, well tolerated, and does not adversely affect engraftment.

Evaluation of a new EMS asthma protocol in New York City: a preliminary report

BACKGROUND

In July 1996, the New York City (NYC) regional EMS implemented a new protocol whereby EMS personnel in the prehospital setting could administer 125 mg of intravenous methyl prednisolone to asthma patients as one of their medical options following telephone consultation with a medical control physician.

OBJECTIVE

To determine whether this protocol had any effect on hospital admission rates or the emergency department (ED) length of stay.

METHODS

This retrospective chart review focused on the 219 (of 603 total) patients who arrived to the ED by ambulance over a two-year period whose ED diagnosis was asthma. There were 81 patient encounters in year 1, and 138 in year 2. Eleven of the year 2 group received prehospital steroids. The study took place at an urban 911 receiving, Level 2 ED.

RESULTS

Of the group who received prehospital steroids, none resulted in hospital admission. Due to the small sample size in the steroid-receiving group, the differences in these admission rates are not yet significant. No differences were detected in the ED length of stay between the two patient groups (157 vs. 160 minutes in year 2, p = 0.9).

CONCLUSION

The differences in admission rates suggested by this study suggest a simple yet potentially powerful tool for improving patient outcome in the treatment of asthma.

Suppression of cytokine-mediated beta2-integrin activation on circulating neutrophils in critically ill patients

The beta2 integrin CD11b plays a central role in inflammation and the systemic inflammatory response syndrome (SIRS). The CD11b molecule activates in two ways: the density of membrane-bound CD11b up-regulates and the molecule undergoes a conformational change that confers adhesiveness to counter-receptors. We studied the kinetics of CD11b activation in patients with SIRS. We found a significantly diminished CD11b activation in response to tumor necrosis factor alpha (TNF-alpha). This affected all circulating polymorphonuclear neutrophils (PMN) and was an intrinsic property of the cells and not due to antagonism by soluble TNF-alpha receptors or loss of cellular receptors for TNF-alpha. Diminished responsiveness correlated with the severity of organ failure and lasted for months in some patients but had no impact on mortality. We speculate that reduced CD11b responsiveness in SIRS contributes to the high risk of recurrent infection, but that it may also be protective against excessive PMN activation within the vascular space.

Cytokine production and bone mineral density at the lumbar spine and femoral neck in premenopausal women

Cytokines such as interleukin-1 (IL-1beta), interleukin-6 (IL-6) and tumor necrosis factor (TNF-alpha) can influence both bone resorption and bone formation. The objective of this cross-sectional study was to examine the relationship between cytokine production by peripheral blood mononuclear cells (PBMC) and bone mineral density (BMD); the annual rate of change in BMD was examined. Subjects participating in a randomized clinical trial entitled the Women's Healthy Lifestyle Project in Allegheny County, Pennsylvania were used. They included 50 healthy premenopausal women, aged 45-52 years, who had regular menses within the past 3 months and were not on replacement estrogens. Dual-energy X-ray absorptiometry measurements at the AP lumbar spine and femoral neck were made at baseline and at the first annual exam using a Hologic QDR 2000 densitometer. Cytokine production of IL-1beta, IL-6, and TNF-alpha by PBMC was measured at the annual exam. The median values for stimulated cytokine production by PBMC were 3.92 ng/ml, 31.3 ng/ml, and 1.05 ng/ml, for IL-1beta, IL-6, and TNF-alpha, respectively. There were modest correlations between cytokine production and cross-sectional BMD, ranging from r = -0.30 to r = -0.13. Trends of greater spinal bone loss were observed in women with "high" (>/=75th percentile) cytokine production of stimulated IL-1beta and IL-6 (IL-1beta: "high" = -1.56% +/- 0.70 versus "low" (<75th percentile) = -0.56% +/- 0.35, P = 0.21). In contrast, greater annual gains in femoral neck BMD were observed in those with high cytokine production of IL-1beta and IL-6 (IL-1beta: high = 3.39% +/- 1.16 versus low = -0. 85 +/- 0.58, P = 0.002). There was no association between stimulated TNF production and annual change in BMD. In this population of healthy premenopausal women, the relationship between cytokine production by PBMC and the rate of change in BMD was significantly different for the lumbar spine and femoral neck, possibly reflecting differences in the proportion of trabecular and cortical bone at these sites.

Differentiation and programmed cell death-related intermediate biomarkers for the development of non-small cell lung cancer: a pilot study

Fifty samples of lung tissue from patients with non-small cell lung cancer were analyzed for the expression and localization of biomarkers related to squamous differentiation and programmed cell death. These markers include tissue transglutaminase (tTG), keratinocyte transglutaminase (kTG), involucrin, loricrin, and Bcl-2. We found that all of these markers are overexpressed in tumors as compared with histologically normal lung epithelium, where expression is minimal. Expression of the oncoprotein, Bcl-2, increased starting in squamous metaplasia and remained elevated in all lesions, including frank carcinoma. In contrast, expression of the other markers was elevated in the histologically abnormal noninvasive lesions but was decreased somewhat in invasive malignancy. In addition, we found that tTG, kTG, and Bcl-2, when expressed, were detected in mutually exclusive areas. These findings suggest that (1) these markers may prove useful, with more extensive testing and clinical correlation, in predicting risk for the development of lung cancer; and (2) pulmonary carcinogenesis may result from the failure of differentiation and programmed cell death mechanisms in the presence of oncogene overexpression rather than through oncogene/tumor suppressor gene abnormalities alone.

Increased interleukin-6 levels in nasal lavage samples following experimental influenza A virus infection

Interleukin-6 (IL-6) is a pleotropic cytokine implicated in the pathogenesis of local inflammation during viral upper respiratory infections. This study determined if experimental influenza A virus infection causes local IL-6 production. Seventeen healthy, adult subjects were intranasally inoculated, by course drops, with a safety-tested strain of influenza A/Kawasaki/86 (H1N1) virus. Nasal lavage samples were collected, symptoms were recorded, and expelled nasal secretions were weighed once before and then daily for 8 days after the virus inoculation. Lavage samples were submitted for virus culture and were examined for IL-6 and IL-4 by enzyme-linked immunosorbent assay. The IL-6, but not IL-4, levels were significantly increased in the nasal lavage samples of the 12 subjects who shed virus but not in those of the 5 subjects who did not shed virus. Moreover, the elevations in IL-6 levels were related temporally to the development of nasal symptoms and secretions but not to systemic symptoms. These results suggest a role for locally produced IL-6 in the pathogenesis and expressed symptomatology of influenza A virus infection.

The role of interleukin-2, interleukin-12, and dendritic cells in cancer therapy

PURPOSE

Recombinant interleukin-2 (rIL-2) administration can mediate regression of solid tumors in patients with melanoma and renal cell carcinoma. A better understanding of the mechanisms of rIL-2-mediated antitumor effects has led to the investigation of novel immunotherapeutic approaches. Two approaches that appear promising include administration of antigen-pulsed dendritic cells (DC) and administration of DC or genetically engineered fibroblasts expressing human interleukin-12 (IL-12). The rationale for these immunotherapeutic approaches and preliminary clinical studies are presented.

PATIENTS AND METHODS

We have conducted a pilot study to evaluate the feasibility of treating melanoma patients with peptide-pulsed DC. Six melanoma patients received 1 to 3 x 10(6) DC pulsed with synthetic melanoma antigenic peptides. The peptide-pulsed DC were infused weekly for 4 weeks. We have also treated 32 patients in a phase I/II trial with IL-12-producing fibroblasts. Patients received escalating doses of cells weekly for 4 weeks, which produced quantities of IL-12 ranging from 10 ng to 9 micrograms/24 hours.

RESULTS

Infusion of melanoma peptide-pulsed DC produced a complete response in one patient, and significant T-cell and DC infiltration of melanoma lesions was observed. Lesional and regional responses have been observed in patients with melanoma, head and neck carcinoma, and breast cancer who received intralesional injections of IL-12-producing fibroblasts. Phase II studies of this approach are planned and will be initiated in the next few months.

CONCLUSIONS

These studies confirm the feasibility of these novel immunotherapeutic approaches and demonstrate their potential antitumor activity. These approaches may be effective in patients with metastatic melanoma and other solid tumors, and they may ultimately be used to improve the efficacy of rIL-2-based immunotherapy.