Publications by authors named "James S Economou"

48 Publications

Interleukin 32 expression in human melanoma.

J Transl Med 2019 04 5;17(1):113. Epub 2019 Apr 5.

Department of Surgery, University of California, Los Angeles, 10833 Le Conte Ave, Los Angeles, CA, 90095, USA.

Background: Various proinflammatory cytokines can be detected within the melanoma tumor microenvironment. Interleukin 32 (IL32) is produced by T cells, NK cells and monocytes/macrophages, but also by a subset of melanoma cells. We sought to better understand the biology of IL32 in human melanoma.

Methods: We analyzed RNA sequencing data from 53 in-house established human melanoma cell lines and 479 melanoma tumors from The Cancer Genome Atlas dataset. We evaluated global gene expression patterns associated with IL32 expression. We also evaluated the impact of proinflammatory molecules TNFα and IFNγ on IL32 expression and dedifferentiation in melanoma cell lines in vitro. In order to study the transcriptional regulation of IL32 in these cell lines, we cloned up to 10.5 kb of the 5' upstream region of the human IL32 gene into a luciferase reporter vector.

Results: A significant proportion of established human melanoma cell lines express IL32, with its expression being highly correlated with a dedifferentiation genetic signature (high AXL/low MITF). Non IL32-expressing differentiated melanoma cell lines exposed to TNFα or IFNγ can be induced to express the three predominant isoforms (α, β, γ) of IL32. Cis-acting elements within this 5' upstream region of the human IL32 gene appear to govern both induced and constitutive gene expression. In the tumor microenvironment, IL32 expression is highly correlated with genes related to T cell infiltration, and also positively correlates with high AXL/low MITF dedifferentiated gene signature.

Conclusions: Expression of IL32 in human melanoma can be induced by TNFα or IFNγ and correlates with a treatment-resistant dedifferentiated genetic signature. Constitutive and induced expression are regulated, in part, by cis-acting sequences within the 5' upstream region.
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http://dx.doi.org/10.1186/s12967-019-1862-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449995PMC
April 2019

Immunotherapy Resistance by Inflammation-Induced Dedifferentiation.

Cancer Discov 2018 08 13;8(8):935-943. Epub 2018 Jun 13.

Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California.

A promising arsenal of targeted and immunotherapy treatments for metastatic melanoma has emerged over the last decade. With these therapies, we now face new mechanisms of tumor-acquired resistance. We report here a patient whose metastatic melanoma underwent dedifferentiation as a resistance mechanism to adoptive T-cell transfer therapy (ACT) to the MART1 antigen, a phenomenon that had been observed only in mouse studies to date. After an initial period of tumor regression, the patient presented in relapse with tumors lacking melanocytic antigens (MART1, gp100) and expressing an inflammation-induced neural crest marker (NGFR). We demonstrate using human melanoma cell lines that this resistance phenotype can be induced by treatment with MART1 T cell receptor-expressing T cells or with TNFα, and that the phenotype is reversible with withdrawal of inflammatory stimuli. This supports the hypothesis that acquired resistance to cancer immunotherapy can be mediated by inflammation-induced cancer dedifferentiation. We report a patient whose metastatic melanoma underwent inflammation-induced dedifferentiation as a resistance mechanism to ACT to the MART1 antigen. Our results suggest that future melanoma ACT protocols may benefit from the simultaneous targeting of multiple tumor antigens, modulating the inflammatory response, and inhibition of inflammatory dedifferentiation-inducing signals. .
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http://dx.doi.org/10.1158/2159-8290.CD-17-1178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6076867PMC
August 2018

Characterization of Postinfusion Phenotypic Differences in Fresh Versus Cryopreserved TCR Engineered Adoptive Cell Therapy Products.

J Immunother 2018 Jun;41(5):248-259

Jonsson Comprehensive Cancer Center, Los Angeles.

Adoptive cell therapy (ACT) consisting of genetically engineered T cells expressing tumor antigen-specific T-cell receptors displays robust initial antitumor activity, followed by loss of T-cell activity/persistence and frequent disease relapse. We characterized baseline and longitudinal T-cell phenotype variations resulting from different manufacturing and administration protocols in patients who received ACT. Patients with melanoma who enrolled in the F5-MART-1 clinical trial (NCT00910650) received infusions of MART-1 T-cell receptors transgenic T cells with MART-1 peptide-pulsed dendritic cell vaccination. Patients were divided into cohorts based on several manufacturing changes in the generation and administration of the transgenic T cells: decreasing ex vivo stimulation/expansion time, increased cell dose, and receiving fresh instead of cryopreserved cells. T-cell phenotypes were analyzed by flow cytometry at baseline and longitudinally in peripheral blood. Transgenic T cells with shorter ex vivo culture/expansion periods displayed significantly increased expression of markers associated with less differentiated naive/memory populations, as well as significantly decreased expression of the inhibitory receptor programmed death 1 (PD1). Patients receiving fresh infusions of transgenic cells demonstrated expansion of central memory T cells and delayed acquisition of PD1 expression compared with patients who received cryopreserved products. Freshly infused transgenic T cells showed persistence and expansion of naive and memory T-cell populations and delayed acquisition of PD1 expression, which correlated with this cohort's superior persistence of transgenic cells and response to dendritic cell vaccines. These results may be useful in designing future ACT protocols.
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http://dx.doi.org/10.1097/CJI.0000000000000216DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5959255PMC
June 2018

Cancer Research in the 21st Century.

Ann Surg 2016 10;264(4):555-65

University of California Los Angeles, Los Angeles, California.

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http://dx.doi.org/10.1097/SLA.0000000000001926DOI Listing
October 2016

Gender bias in biomedical research.

Authors:
James S Economou

Surgery 2014 Nov 26;156(5):1061-5. Epub 2014 Sep 26.

Department of Surgery, University of California, Los Angeles, CA. Electronic address:

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http://dx.doi.org/10.1016/j.surg.2014.07.005DOI Listing
November 2014

Alpha fetoprotein DNA prime and adenovirus boost immunization of two hepatocellular cancer patients.

J Transl Med 2014 Apr 5;12:86. Epub 2014 Apr 5.

University of Pittsburgh Cancer Institute, Departments of Medicine, Surgery, and Immunology, University of Pittsburgh, 5117 Centre Avenue, PA, Pittsburgh 15213, USA.

Background: Alpha fetoprotein (AFP) is an oncofetal antigen over-expressed by many hepatocellular cancers (HCC). We previously demonstrated that HLA-A2-restricted epitopes derived from AFP are immunogenic in vitro and in vivo despite high circulating levels of this oncofetal antigen. In order to test a more broadly applicable, HLA-unrestricted, inexpensive, cell-free vaccine platform capable of activating tumor antigen-specific CD8+ and CD4+ T cells, we tested full length AFP in a plasmid DNA construct in combination with an AFP-expressing replication-deficient adenovirus (AdV) in a prime-boost vaccine strategy.

Methods: HCC patients who had an AFP+ tumor and previous treatment for HCC were screened and two patients received vaccination with three plasmid DNA injections followed by a single AdV injection, all delivered intramuscularly (i.m.).

Results: The vaccine was well tolerated and safe. Both patients showed immunologic evidence of immunization. The first patient had a weak AFP-specific T cell response, a strong AdV-specific cellular response and recurred with an AFP-expressing HCC at nine months. The second patient developed a strong AFP-specific CD8+ and CD4+ cellular response and an AdV neutralizing antibody response, and recurred at 18 months without an increase in serum AFP.

Conclusions: The AFP DNA prime-AdV boost vaccine was safe and immunogenic. Circulating anti-AdV neutralizing antibodies at baseline did not prohibit the development of AFP-specific cellular immunity. The patient who developed CD8+ and CD4+ AFP-specific T cell immunity had more favorable progression-free survival. The observations with these two patients support development of this vaccine strategy in a larger clinical trial.

Trial Registration: ClinicalTrials.gov: NCT00093548.
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http://dx.doi.org/10.1186/1479-5876-12-86DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021640PMC
April 2014

Aberrant apoptotic machinery confers melanoma dual resistance to BRAF(V600E) inhibitor and immune effector cells: immunosensitization by a histone deacetylase inhibitor.

Am J Clin Exp Immunol 2014 27;3(1):43-56. Epub 2014 Feb 27.

Department of Surgery, The Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, University of California Los Angeles 90095, USA ; Department of Microbiology, Immunology and Molecular Genetics, The Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, University of California Los Angeles 90095, USA ; Department of Molecular and Medical Pharmacology, The Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, University of California Los Angeles 90095, USA.

BRAF(V600E)-inhibitors (BRAFi; e.g., vemurafenib) and modern immune-based therapies such as PD-1/PD-L1 and CTLA-4 checkpoints blockade and adoptive cell transfer (ACT) have significantly improved the care of melanoma patients. Having these two effective (BRAFi and immunotherapy) therapies raises the question whether there is a rational biological basis for using them in combination. We developed an in vitro model to determine whether tumor resistance mechanisms to a small molecule inhibitor of a driver oncogene, and to cytotoxic T lymphocyte (CTL)- and natural killer (NK) cell-delivered apoptotic death signals were exclusive or intersecting. We generated melanoma sublines resistant to BRAFi vemurafenib and to CTL recognizing the MART-1 melanoma antigen. Vemurafenib-resistant (VemR) sublines were cross-resistant to MART CTL and NK cells indicating that a common apoptotic pathway governing tumor response to both modalities was disrupted. Pretreatment of VemR melanomas with a histone deacetylase inhibitor (HDACi) restored sensitivity to MART CTL and NK apoptosis by skewing the apoptotic gene programs towards a proapoptotic phenotype. Our in vitro findings suggest that during the course of acquisition of BRAFi resistance, melanomas develop cross-resistance to CTL- and NK-killing. Further, aberrant apoptotic pathways, amenable by an FDA-approved chromatin remodeling drug, regulate tumor resistance mechanisms to immune effector cells. These results may provide rational molecular basis for further investigations to combine these therapies clinically.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3960761PMC
March 2014

Histone deacetylase inhibitor sensitizes apoptosis-resistant melanomas to cytotoxic human T lymphocytes through regulation of TRAIL/DR5 pathway.

J Immunol 2014 Apr 17;192(8):3981-9. Epub 2014 Mar 17.

Department of Surgery, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095;

Modern immune therapies (PD-1/PD-L1 and CTLA-4 checkpoints blockade and adoptive cell transfer) have remarkably improved the response rates of metastatic melanoma. These modalities rely on the killing potential of CTL as proximal mediator of antimelanoma responses. Mechanisms of tumor resistance to and the predominant cytotoxic pathway(s) used by melanoma-reactive CTL are important outcome determinants. We hypothesized that downmodulation of death receptors (DRs) in addition to aberrant apoptotic signaling might confer resistance to death signals delivered by CTL. To test these two hypotheses, we used an in vitro model of MART CTL-resistant melanoma sublines. TCR-transgenic and patient-derived CTLs used the TRAIL cytotoxic pathway through DR5. Furthermore, recombinant human TRAIL and drozitumab (anti-DR5 agonistic mAb) were used to explicitly verify the contribution of the DR5/TRAIL pathway in killing melanomas. CTL resistance was due to DR5 downregulation and an inverted ratio of pro- to antiapoptotic molecules, both of which were reversed by the histone deacetylase inhibitor suberoylanilide hydroxanic acid. Apoptosis negative (c-IAP-2 and Bcl-xL) and positive (DR5) regulators were potential incriminators partly regulating CTL sensitivity. These preclinical findings suggest that exposure to this chromatin remodeling drug of immune-resistant melanomas can skew toward an intracellular proapoptotic milieu, increase DR expression, and overcome acquired immune resistance.
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http://dx.doi.org/10.4049/jimmunol.1302532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4136528PMC
April 2014

Adoptive transfer of MART-1 T-cell receptor transgenic lymphocytes and dendritic cell vaccination in patients with metastatic melanoma.

Clin Cancer Res 2014 May 14;20(9):2457-65. Epub 2014 Mar 14.

Authors' Affiliations: Departments of Medicine, Surgery, Pathology and Laboratory Medicine, Microbiology, Immunology and Molecular Genetics, and Molecular and Medical Pharmacology; Jonsson Comprehensive Cancer Center; Department of Ophthalmology, Jules Stein Eye Institute; Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research; Howard Hughes Medical Institute, University of California, Los Angeles (UCLA); The Angeles Clinic Research Institute, Los Angeles; Department of Medicine, University of California San Diego (UCSD) Moores Cancer Center, La Jolla; Divisions of Chemistry and Biology, California Institute of Technology, Pasadena, California; Department of Medical and Molecular Genetics, Indiana University, and the Indiana University Viral Production Facility (IU VPF), Indianapolis, Indiana; Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada; Mayo Clinic Scottsdale, Scottsdale, Arizona; Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut; and Center for Immunology, Roswell Park Cancer Institute, Buffalo, New York.

Purpose: It has been demonstrated that large numbers of tumor-specific T cells for adoptive cell transfer (ACT) can be manufactured by retroviral genetic engineering of autologous peripheral blood lymphocytes and expanding them over several weeks. In mouse models, this therapy is optimized when administered with dendritic cell (DC) vaccination. We developed a short 1-week manufacture protocol to determine the feasibility, safety, and antitumor efficacy of this double cell therapy.

Experimental Design: A clinical trial (NCT00910650) adoptively transferring MART-1 T-cell receptor (TCR) transgenic lymphocytes together with MART-1 peptide-pulsed DC vaccination in HLA-A2.1 patients with metastatic melanoma. Autologous TCR transgenic cells were manufactured in 6 to 7 days using retroviral vector gene transfer, and reinfused with (n = 10) or without (n = 3) prior cryopreservation.

Results: A total of 14 patients with metastatic melanoma were enrolled and 9 of 13 treated patients (69%) showed evidence of tumor regression. Peripheral blood reconstitution with MART-1-specific T cells peaked within 2 weeks of ACT, indicating rapid in vivo expansion. Administration of freshly manufactured TCR transgenic T cells resulted in a higher persistence of MART-1-specific T cells in the blood as compared with cryopreserved. Evidence that DC vaccination could cause further in vivo expansion was only observed with ACT using noncryopreserved T cells.

Conclusion: Double cell therapy with ACT of TCR-engineered T cells with a very short ex vivo manipulation and DC vaccines is feasible and results in antitumor activity, but improvements are needed to maintain tumor responses.
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http://dx.doi.org/10.1158/1078-0432.CCR-13-3017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4070853PMC
May 2014

Multifunctional T-cell analyses to study response and progression in adoptive cell transfer immunotherapy.

Cancer Discov 2013 Apr 21;3(4):418-29. Epub 2013 Mar 21.

NanoSystems Biology Cancer Center, Division of Physics, California Institute of Technology, Pasadena, CA 91125, USA.

Unlabelled: Adoptive cell transfer (ACT) of genetically engineered T cells expressing cancer-specific T-cell receptors (TCR) is a promising cancer treatment. Here, we investigate the in vivo functional activity and dynamics of the transferred cells by analyzing samples from 3 representative patients with melanoma enrolled in a clinical trial of ACT with TCR transgenic T cells targeted against the melanosomal antigen MART-1. The analyses included evaluating 19 secreted proteins from individual cells from phenotypically defined T-cell subpopulations, as well as the enumeration of T cells with TCR antigen specificity for 36 melanoma antigens. These analyses revealed the coordinated functional dynamics of the adoptively transferred, as well as endogenous, T cells, and the importance of highly functional T cells in dominating the antitumor immune response. This study highlights the need to develop approaches to maintaining antitumor T-cell functionality with the aim of increasing the long-term efficacy of TCR-engineered ACT immunotherapy.

Significance: A longitudinal functional study of adoptively transferred TCR–engineered lymphocytes yielded revealing snapshots for understanding the changes of antitumor responses over time in ACT immunotherapy of patients with advanced melanoma.
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http://dx.doi.org/10.1158/2159-8290.CD-12-0383DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3716460PMC
April 2013

Allelic exclusion and peripheral reconstitution by TCR transgenic T cells arising from transduced human hematopoietic stem/progenitor cells.

Mol Ther 2013 May 5;21(5):1044-54. Epub 2013 Feb 5.

Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California, USA.

Transduction and transplantation of human hematopoietic stem/progenitor cells (HSPC) with the genes for a T-cell receptor (TCR) that recognizes a tumor-associated antigen may lead to sustained long-term production of T cells expressing the TCR and confer specific antitumor activity. We evaluated this using a lentiviral vector (CCLc-MND-F5) carrying cDNA for a human TCR specific for an HLA-A*0201-restricted peptide of Melanoma Antigen Recognized by T cells (MART-1). CD34(+) HSPC were transduced with the F5 TCR lentiviral vector or mock transduced and transplanted into neonatal NSG mice or NSG mice transgenic for human HLA-A*0201 (NSG-A2). Human CD8(+) and CD4(+) T cells expressing the human F5 TCR were present in the thymus, spleen, and peripheral blood after 4-5 months. Expression of human HLA-A*0201 in NSG-A2 recipient mice led to significantly increased numbers of human CD8(+) and CD4(+) T cells expressing the F5 TCR, compared with control NSG recipients. Transduction of the human CD34(+) HSPC by the F5 TCR transgene caused a high degree of allelic exclusion, potently suppressing rearrangement of endogenous human TCR-β genes during thymopoiesis. In summary, we demonstrated the feasibility of engineering human HSPC to express a tumor-specific TCR to serve as a long-term source of tumor-targeted mature T cells for immunotherapy of melanoma.
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http://dx.doi.org/10.1038/mt.2013.8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3666644PMC
May 2013

A society in transition: presidential remarks at the 65th Annual SSO Cancer Symposium.

Authors:
James S Economou

Ann Surg Oncol 2012 Oct 18;19(11):3293-7. Epub 2012 Jul 18.

Division of Surgical Oncology, University of California, Los Angeles, CA, USA.

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http://dx.doi.org/10.1245/s10434-012-2443-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3442172PMC
October 2012

T cell receptor (TCR)-transgenic CD8 lymphocytes rendered insensitive to transforming growth factor beta (TGFβ) signaling mediate superior tumor regression in an animal model of adoptive cell therapy.

J Transl Med 2012 Jun 19;10:127. Epub 2012 Jun 19.

Department of Surgery, University of California, Los Angeles, CA 90095, USA.

Tumor antigen-reactive T cells must enter into an immunosuppressive tumor microenvironment, continue to produce cytokine and deliver apoptotic death signals to affect tumor regression. Many tumors produce transforming growth factor beta (TGFβ), which inhibits T cell activation, proliferation and cytotoxicity. In a murine model of adoptive cell therapy, we demonstrate that transgenic Pmel-1 CD8 T cells, rendered insensitive to TGFβ by transduction with a TGFβ dominant negative receptor II (DN), were more effective in mediating regression of established B16 melanoma. Smaller numbers of DN Pmel-1 T cells effectively mediated tumor regression and retained the ability to produce interferon-γ in the tumor microenvironment. These results support efforts to incorporate this DN receptor in clinical trials of adoptive cell therapy for cancer.
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http://dx.doi.org/10.1186/1479-5876-10-127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3507675PMC
June 2012

Proteasome inhibition blocks NF-κB and ERK1/2 pathways, restores antigen expression, and sensitizes resistant human melanoma to TCR-engineered CTLs.

Mol Cancer Ther 2012 Jun 24;11(6):1332-41. Epub 2012 Apr 24.

Department of Surgery and the Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, University of California at Los Angeles, Los Angeles, CA 90095, USA.

Adoptive cell transfer (ACT) of ex vivo engineered autologous lymphocytes encoding high-affinity MART-1/HLA-A*0201-specific T-cell receptor (TCR)α/β chains (F5 CTL), densely infiltrate into sites of metastatic disease, mediating dramatic but partial clinical responses in patients with melanoma. We hypothesized that MART-1 downmodulation in addition to aberrant apoptotic/survival signaling could confer resistance to death signals delivered by transgenic CTLs. To explore this hypothesis, we established an in vitro model of resistant (R) lines from MART-1(+)/HLA-A*0201(+) F5 CTL-sensitive parental (P) lines under serial F5 CTL-selective pressure. We have recently reported that several melanoma R lines, while retaining MART-1 expression, exhibited constitutive NF-κB activation and overexpression of NF-κB-dependent resistance factors. Another established melanoma cell line M244, otherwise sensitive to F5 CTL, yielded R lines after serial F5 CTL-selective pressure, which had both reduced MART-1 expression levels, thus, could not be recognized, and were resistant to CTL-delivered apoptotic death signals. The proteasome inhibitor bortezomib blocked NF-κB activity, decreased phospho-ERK1/2, increased phospho-c-jun-NH(2)-kinase (p-JNK) levels, reduced expression of resistance factors, restored MART-1 expression to sufficient levels, which in combination allowed M244R lines be sensitized to F5 CTL killing. These findings suggest that proteasome inhibition in immune resistant tumors can restore proapoptotic signaling and improve tumor antigen expression.
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http://dx.doi.org/10.1158/1535-7163.MCT-11-0814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3374071PMC
June 2012

T cell receptor transgenic lymphocytes infiltrating murine tumors are not induced to express foxp3.

J Hematol Oncol 2011 Nov 23;4:48. Epub 2011 Nov 23.

Departments of Surgery, University of California, Los Angeles, Los Angeles, CA 90095, USA.

Regulatory T cells (Treg) that express the transcription factor Foxp3 are enriched within a broad range of murine and human solid tumors. The ontogeny of these Foxp3 Tregs - selective accumulation or proliferation of natural thymus-derived Treg (nTreg) or induced Treg (iTreg) converted in the periphery from naïve T cells - is not known. We used several strains of mice in which Foxp3 and EGFP are coordinately expressed to address this issue. We confirmed that Foxp3-positive CD4 T cells are enriched among tumor-infiltrating lymphocytes (TIL) and splenocytes (SPL) in B16 murine melanoma-bearing C57BL/6 Foxp3(EGFP) mice. OT-II Foxp3(EGFP) mice are essentially devoid of nTreg, having transgenic CD4 T cells that recognize a class II-restricted epitope derived from ovalbumin; Foxp3 expression could not be detected in TIL or SPL in these mice when implanted with ovalbumin-transfected B16 tumor (B16-OVA). Likewise, TIL isolated from B16 tumors implanted in Pmel-1 Foxp3(EGFP) mice, whose CD8 T cells recognize a class I-restricted gp100 epitope, were not induced to express Foxp3. All of these T cell populations - wild-type CD4, pmel CD8 and OTII CD4 - could be induced in vitro to express Foxp3 by engagement of their T cell receptor (TCR) and exposure to transforming growth factor β (TGFβ). B16 melanoma produces TGFβ and both pmel CD8 and OTII CD4 express TCR that should be engaged within B16 and B16-OVA respectively. Thus, CD8 and CD4 transgenic T cells in these animal models failed to undergo peripheral induction of Foxp3 in a tumor microenvironment.
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http://dx.doi.org/10.1186/1756-8722-4-48DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3245424PMC
November 2011

Immunomodulation by imiquimod in patients with high-risk primary melanoma.

J Invest Dermatol 2012 Jan 18;132(1):163-9. Epub 2011 Aug 18.

Division of Dermatology, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, California 90502, USA.

Imiquimod is a synthetic Toll-like receptor 7 (TLR7) agonist approved for the topical treatment of actinic keratoses, superficial basal cell carcinoma, and genital warts. Imiquimod leads to an 80-100% cure rate of lentigo maligna; however, studies of invasive melanoma are lacking. We conducted a pilot study to characterize the local, regional, and systemic immune responses induced by imiquimod in patients with high-risk melanoma. After treatment of the primary melanoma biopsy site with placebo or imiquimod cream, we measured immune responses in the treated skin, sentinel lymph nodes (SLNs), and peripheral blood. Treatment of primary melanomas with 5% imiquimod cream was associated with an increase in both CD4+ and CD8+ T cells in the skin, and CD4+ T cells in the SLN. Most of the CD8+ T cells in the skin were CD25 negative. We could not detect any increases in CD8+ T cells specifically recognizing HLA-A(*)0201-restricted melanoma epitopes in the peripheral blood. The findings from this small pilot study demonstrate that topical imiquimod treatment results in enhanced local and regional T-cell numbers in both the skin and SLN. Further research into TLR7 immunomodulating pathways as a basis for effective immunotherapy against melanoma in conjunction with surgery is warranted.
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http://dx.doi.org/10.1038/jid.2011.247DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3229834PMC
January 2012

CTLA4 blockade induces frequent tumor infiltration by activated lymphocytes regardless of clinical responses in humans.

Clin Cancer Res 2011 Jun 10;17(12):4101-9. Epub 2011 May 10.

Division of Hematology-Oncology, 11-934 Factor Building, UCLA Medical Center, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.

Background: CTLA4 blocking monoclonal antibodies provide durable clinical benefit in a subset of patients with advanced melanoma mediated by intratumoral lymphocytic infiltrates. A key question is defining whether the intratumoral infiltration (ITI) is a differentiating factor between patients with and without tumor responses.

Methods: Paired baseline and postdosing tumor biopsy specimens were prospectively collected from 19 patients with metastatic melanoma, including 3 patients with an objective tumor response, receiving the anti-CTLA4 antibody tremelimumab within a clinical trial with primary endpoint of quantitating CD8(+) cytotoxic T-lymphocyte (CTL) infiltration in tumors. Samples were analyzed for cell density by automated imaging capture and further characterized for functional lymphocyte properties by assessing the cell activation markers HLA-DR and CD45RO, the cell proliferation marker Ki67, and the regulatory T-cell marker FOXP3.

Results: There was a highly significant increase in ITI by CD8(+) cells in biopsy samples taken after tremelimumab treatment. This included increases between 1-fold and 100-fold changes in 14 of 18 evaluable cases regardless of clinical tumor response or progression. There was no difference between the absolute number, location, or cell density of infiltrating cells between clinical responders and patients with nonresponding lesions that showed acquired intratumoral infiltrates. There were similar levels of expression of T-cell activation markers (CD45RO, HLA-DR) in both groups and no difference in markers for cell replication (Ki67) or the suppressor cell marker FOXP3.

Conclusion: CTLA4 blockade induces frequent increases in ITI by T cells despite which only a minority of patients have objective tumor responses.
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http://dx.doi.org/10.1158/1078-0432.CCR-11-0407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3117971PMC
June 2011

Molecular mechanism of MART-1+/A*0201+ human melanoma resistance to specific CTL-killing despite functional tumor-CTL interaction.

Cancer Res 2011 Feb 15;71(4):1406-17. Epub 2010 Dec 15.

Department of Surgery, Molecular and Medical Pharmacology, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, California, USA.

Durable responses in metastatic melanoma patients remain generally difficult to achieve. Adoptive cell therapy (ACT) with ex vivo engineered lymphocytes expressing high affinity T-cell receptors (TCRα/β) for the melanoma antigen MART-1₂₇₋₃₅/HLA-A*0201 [recognized by F5 cytotoxic T lymphocytes (F5 CTL)] has been found to benefit certain patients. However, many other patients are inherently unresponsive and/or relapse for unknown reasons. To analyze the basis for the acquired resistance and strategies to reverse it, we established F5 CTL-resistant (R) human melanoma clones from relatively sensitive parental lines under selective F5 CTL pressure. Surface MART-1₂₇₋₃₅/HLA-A*0201 in these clones was unaltered and F5 CTLs recognized and interacted with them similar to the parental lines. Nevertheless, the R clones were resistant to F5 CTL killing, exhibited hyperactivation of the NF-κB survival pathway, and overexpression of the antiapoptotic genes B cell lymphoma protein 2 (Bcl-2), Bcl-2 related gene (long alternatively spliced variant of Bcl-x gene; Bcl-(xL)), and myeloid cell differentiation 1 (Mcl-1). Sensitivity to F5 CTL-killing could be increased by pharmacological inhibition of the NF-κB pathway, Bcl-2 family members, or the proteasome, the latter of which reduced NF-κB activity and diminished antiapoptotic gene expression. Specific gene-silencing (by siRNA) confirmed the protective role of antiapoptotic factors by reversing R clone resistance. Together, our findings suggest that long-term immunotherapy may impose a selection for the development of resistant cells that are unresponsive to highly avid and specific melanoma-reactive CTLs, despite maintaining expression of functional peptide:MHC complexes, due to activation of antiapoptotic signaling pathways. Though unresponsive to CTL, our results argue that resistant cells can be resensitized to immunotherapy with coadministration of targeted inhibitors to antiapoptotic survival pathways.
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http://dx.doi.org/10.1158/0008-5472.CAN-10-1296DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4180868PMC
February 2011

Radiation enhances regulatory T cell representation.

Int J Radiat Oncol Biol Phys 2011 Nov 17;81(4):1128-35. Epub 2010 Nov 17.

Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1714, USA.

Purpose: Immunotherapy could be a useful adjunct to standard cytotoxic therapies such as radiation in patients with micrometastatic disease, although successful integration of immunotherapy into treatment protocols will require further understanding of how standard therapies affect the generation of antitumor immune responses. This study was undertaken to evaluate the impact of radiation therapy (RT) on immunosuppressive T regulatory (Treg) cells.

Methods And Materials: Treg cells were identified as a CD4(+)CD25(hi)Foxp3(+) lymphocyte subset, and their fate was followed in a murine TRAMP C1 model of prostate cancer in mice with and without RT.

Results: CD4(+)CD25(hi)Foxp3(+) Treg cells increased in immune organs after local leg or whole-body radiation. A large part, but not all, of this increase after leg-only irradiation could be ascribed to radiation scatter and Treg cells being intrinsically more radiation resistant than other lymphocyte subpopulations, resulting in their selection. Their functional activity on a per-cell basis was not affected by radiation exposure. Similar findings were made with mice receiving local RT to murine prostate tumors growing in the leg. The importance of the Treg cell population in the response to RT was shown by systemic elimination of Treg cells, which greatly enhanced radiation-induced tumor regression.

Conclusions: We conclude that Treg cells are more resistant to radiation than other lymphocytes, resulting in their preferential increase. Treg cells may form an important homeostatic mechanism for tissues injured by radiation, and in a tumor context, they may assist in immune evasion during therapy. Targeting this population may allow enhancement of radiotherapeutic benefit through immune modulation.
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http://dx.doi.org/10.1016/j.ijrobp.2010.09.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3117954PMC
November 2011

MHC-I-restricted melanoma antigen specific TCR-engineered human CD4+ T cells exhibit multifunctional effector and helper responses, in vitro.

Clin Immunol 2010 Sep 23;136(3):338-47. Epub 2010 May 23.

Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA.

MHC class I-restricted human melanoma epitope MART-1(27-35) specific TCR-engineered CD4+CD25- T cells synthesize Th1 type cytokines and exhibit cytolytic effector function upon cognate stimulation. A detailed characterization of such TCR-engineered CD4+CD25- T cells now reveals that they are multifunctional. For example, they undergo multiple rounds of division, synthesize cytokines (IFN-gamma, TNF-alpha, IL-2, and MIP1ss), lyse target cells, and "help" the expansion of the MART-1(27-35) specific CD8+ T cells when stimulated by the MART-1(27-35) peptide pulsed DC. Multiparametric analyses reveal that a single TCR-engineered CD4+ T cell can perform as many as five different functions. Nearly 100% MART-1(27-35) specific TCR expressing CD4+ T cells can be generated through retroviral vector-based transduction and one round of in vitro stimulation by the peptide pulsed DC. MHC class I-restricted tumor epitope specific TCR transduced CD4+ T cells, therefore, could be useful in immunotherapeutic strategies for melanoma or other human malignancies.
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http://dx.doi.org/10.1016/j.clim.2010.04.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2917536PMC
September 2010

Enhanced antitumor activity induced by adoptive T-cell transfer and adjunctive use of the histone deacetylase inhibitor LAQ824.

Cancer Res 2009 Nov 27;69(22):8693-9. Epub 2009 Oct 27.

Department of Medicine, Division of Hematology/Oncology, Jonsson Comprehensive Cancer Center, University of California-Los Angeles, Los Angeles, California, USA.

Tumors grow in the presence of antigen-specific T cells, suggesting the existence of intrinsic cancer cell escape mechanisms. We hypothesized that a histone deacetylase (HDAC) inhibitor could sensitize tumor cells to immunotherapy because this class of agents has been reported to increase tumor antigen expression and shift gene expression to a proapoptotic milieu in cancer cells. To test this question, we treated B16 murine melanoma with the combination of the HDAC inhibitor LAQ824 and the adoptive transfer of gp100 melanoma antigen-specific pmel-1 T cells. The combined therapy significantly improved antitumor activity through several mechanisms: (a) increase in MHC and tumor-associated antigen expression by tumor cells; (b) decrease in competing endogenous lymphocytes in recipient mice, resulting in a proliferative advantage for the adoptively transferred cells; and (c) improvement in the functional activity of the adoptively transferred lymphocytes. We confirmed the beneficial effects of this HDAC inhibitor as a sensitizer to immunotherapy in a different model of prophylactic prime-boost vaccination with the melanoma antigen tyrosinase-related protein 2, which also showed a significant improvement in antitumor activity against B16 melanoma. In conclusion, the HDAC inhibitor LAQ824 significantly enhances tumor immunotherapy through effects on target tumor cells as well as improving the antitumor activity of tumor antigen-specific lymphocytes.
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http://dx.doi.org/10.1158/0008-5472.CAN-09-1456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2779578PMC
November 2009

Dendritic cell vaccination combined with CTLA4 blockade in patients with metastatic melanoma.

Clin Cancer Res 2009 Oct 29;15(19):6267-76. Epub 2009 Sep 29.

Department of Medicine, Division of Hematology/Oncology, University of California at Los Angeles, Los Angeles, California 90095-1782, USA.

Purpose: Tumor antigen-loaded dendritic cells (DC) are believed to activate antitumor immunity by stimulating T cells, and CTL-associated antigen 4 (CTLA4)-blocking antibodies should release a key negative regulatory pathway on T cells. The combination was tested in a phase I clinical trial in patients with advanced melanoma.

Experimental Design: Autologous DC were pulsed with MART-1(26-35) peptide and administered with a dose escalation of the CTLA4-blocking antibody tremelimumab. Sixteen patients were accrued to five dose levels. Primary end points were safety and immune effects; clinical efficacy was a secondary end point.

Results: Dose-limiting toxicities of grade 3 diarrhea and grade 2 hypophysitis developed in two of three patients receiving tremelimumab at 10 mg/kg monthly. Four patients had an objective tumor response, two partial responses and two complete responses, all melanoma free between 2 and 4 years after study initiation. There was no difference in immune monitoring results between patients with an objective tumor response and those without a response. Exploratory gene expression analysis suggested that immune-related gene signatures, in particular for B-cell function, may be important in predicting response.

Conclusion: The combination of MART-1 peptide-pulsed DC and tremelimumab results in objective and durable tumor responses at the higher range of the expected response rate with either agent alone.
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http://dx.doi.org/10.1158/1078-0432.CCR-09-1254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2765061PMC
October 2009

Intratumoral immune cell infiltrates, FoxP3, and indoleamine 2,3-dioxygenase in patients with melanoma undergoing CTLA4 blockade.

Clin Cancer Res 2009 Jan;15(1):390-9

Division of Hematology/Oncology, Department of Medicine, University of California-Los Angeles, Los Angeles, California 90095-1782, USA.

Purpose: CTL-associated antigen 4 (CTLA4)-blocking monoclonal antibodies induce long-term regression of metastatic melanoma in some patients, but the exact mechanism is unknown. In this study, biopsies of selected accessible tumor lesions from patients treated with tremelimumab were examined to further elucidate the mechanism of its antitumor activity.

Experimental Design: Fifteen tumor biopsies from 7 patients who had been treated with tremelimumab (CP-675,206) were collected. Samples were analyzed for melanoma markers, immune cell subset markers, the presence of the T regulatory-specific transcription factor FoxP3 and the immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO).

Results: Clinically responding lesions had diffuse intratumoral infiltrates of CD8(+) T cells that were markedly increased in cases where comparison with a baseline biopsy was available. Nonregressing lesions had sparse, patchy CD8(+) intratumoral infiltrates. Patients with regressing lesions had an increased frequency of CD8(+) cells with or without a concomitant increase in CD4(+) cells. Two of 3 responding patients with paired samples showed a slight increase in the number of FoxP3(+) cells in the postdosing biopsies. In patients with regressing lesions who had paired samples, the intensity of IDO staining in macrophages and/or melanoma cells showed no clear pattern of change postdosing.

Conclusions: Administration of tremelimumab was associated with massive intratumoral infiltrates of CD8(+) CTLs in patients with regressing tumors but had varying effects on intratumoral infiltrates of CD4(+) and FoxP3(+) cells or intratumoral expression of IDO.
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http://dx.doi.org/10.1158/1078-0432.CCR-08-0783DOI Listing
January 2009

CD4+CD25- T cells transduced to express MHC class I-restricted epitope-specific TCR synthesize Th1 cytokines and exhibit MHC class I-restricted cytolytic effector function in a human melanoma model.

J Immunol 2008 Jul;181(2):1063-70

Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA.

Cytolytic T cell-centric active specific and adoptive immunotherapeutic approaches might benefit from the simultaneous engagement of CD4(+) T cells. Considering the difficulties in simultaneously engaging CD4(+) and CD8(+) T cells in tumor immunotherapy, especially in an Ag-specific manner, redirecting CD4(+) T cells to MHC class I-restricted epitopes through engineered expression of MHC class I-restricted epitope-specific TCRs in CD4(+) T cells has emerged as a strategic consideration. Such TCR-engineered CD4(+) T cells have been shown to be capable of synthesizing cytokines as well as lysing target cells. We have conducted a critical examination of functional characteristics of CD4(+) T cells engineered to express the alpha- and beta-chains of a high functional avidity TCR specific for the melanoma epitope, MART-1(27-35), as a prototypic human tumor Ag system. We found that unpolarized CD4(+)CD25(-) T cells engineered to express the MART-1(27-35) TCR selectively synthesize Th1 cytokines and exhibit a potent Ag-specific lytic granule exocytosis-mediated cytolytic effector function of comparable efficacy to that of CD8(+) CTL. Such TCR engineered CD4(+) T cells, therefore, might be useful in clinical immunotherapy.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2715965PMC
http://dx.doi.org/10.4049/jimmunol.181.2.1063DOI Listing
July 2008

Detailed analysis of immunologic effects of the cytotoxic T lymphocyte-associated antigen 4-blocking monoclonal antibody tremelimumab in peripheral blood of patients with melanoma.

J Transl Med 2008 May 1;6:22. Epub 2008 May 1.

Department of Surgery, Division of Surgical Oncology, University of California Los Angeles, Los Angeles, CA, USA.

Background: CTLA4-blocking antibodies induce tumor regression in a subset of patients with melanoma. Analysis of immune parameters in peripheral blood may help define how responses are mediated.

Methods: Peripheral blood from HLA-A*0201-positive patients with advanced melanoma receiving tremelimumab (formerly CP-675,206) at 10 mg/kg monthly was repeatedly sampled during the first 4 cycles. Samples were analyzed by 1) tetramer and ELISPOT assays for reactivity to CMV, EBV, MART1, gp100, and tyrosinase; 2) activation HLA-DR and memory CD45RO markers on CD4+/CD8+ cells; and 3) real-time quantitative PCR of mRNA for FoxP3 transcription factor, preferentially expressed by T regulatory cells. The primary endpoint was difference in MART1-specific T cells by tetramer assay. Immunological data were explored for significant trends using clustering analysis.

Results: Three of 12 patients eligible for immune monitoring had tumor regression lasting > 2 years without relapse. There was no significant change in percent of MART1-specific T cells by tetramer assay. Additionally, there was no generalized trend toward postdosing changes in other antigen-specific CD8+ cell populations, FoxP3 transcripts, or overall changes in surface expression of T-cell activation or memory markers. Unsupervised hierarchical clustering based on immune monitoring data segregated patients randomly. However, clustering according to T-cell activation or memory markers separated patients with clinical response and most patients with inflammatory toxicity into a common subgroup.

Conclusion: Administration of CTLA4-blocking antibody tremelimumab to patients with advanced melanoma results in a subset of patients with long-lived tumor responses. T-cell activation and memory markers served as the only readout of the pharmacodynamic effects of this antibody in peripheral blood.

Clinical Trial Registration Number: NCT00086489.
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http://dx.doi.org/10.1186/1479-5876-6-22DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2412852PMC
May 2008

Adenovirus MART-1-engineered autologous dendritic cell vaccine for metastatic melanoma.

J Immunother 2008 Apr;31(3):294-309

Department of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA.

We performed a phase 1/2 trial testing the safety, toxicity, and immune response of a vaccine consisting of autologous dendritic cells (DCs) transduced with a replication-defective adenovirus (AdV) encoding the full-length melanoma antigen MART-1/Melan-A (MART-1). This vaccine was designed to activate MART-1-specific CD+8 and CD4+ T cells. Metastatic melanoma patients received 3 injections of 10(6) or 10(7) DCs, delivered intradermally. Cell surface phenotype and cytokine production of the DCs used for the vaccines were tested, and indicated intermediate maturity. CD8+ T-cell responses to MART-1 27-35 were assessed by both major histocompatibility complex class I tetramer and interferon (IFN)-gamma enzyme-linked immunosorbent spot (ELISPOT) before, during, and after each vaccine and CD4+ T-cell responses to MART-1 51-73 were followed by IFN-gamma ELISPOT. We also measured antigen response breadth. Determinant spreading from the immunizing antigen MART-1 to other melanoma antigens [gp100, tyrosinase, human melanoma antigen-A3 (MAGE-A3)] was assessed by IFN-gamma ELISPOT. Twenty-three patients were enrolled and 14 patients received all 3 scheduled DC vaccines. Significant CD8+ and/or CD4+ MART-1-specific T-cell responses were observed in 6/11 and 2/4 patients evaluated, respectively, indicating that the E1-deleted adenovirus encoding the cDNA for MART-1/Melan-A (AdVMART1)/DC vaccine activated both helper and killer T cells in vivo. Responses in CD8+ and CD4+ T cells to additional antigens were noted in 2 patients. The AdVMART1-transduced DC vaccine was safe and immunogenic in patients with metastatic melanoma.
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http://dx.doi.org/10.1097/CJI.0b013e31816a8910DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3651040PMC
April 2008

Spontaneous and vaccine induced AFP-specific T cell phenotypes in subjects with AFP-positive hepatocellular cancer.

Cancer Immunol Immunother 2007 Dec 24;56(12):1931-43. Epub 2007 May 24.

Department of Medicine, Surgery and Immunology University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA 15213, USA.

We are investigating the use of Alpha Fetoprotein (AFP) as a tumor rejection antigen for hepatocellular carcinoma (HCC). We recently completed vaccination of 10 AFP+/HLA-A2.1+ HCC subjects with AFP peptide-pulsed autologous dendritic cells (DC). There were increased frequencies of circulating AFP-specific T cells and of IFNgamma-producing AFP-specific T cells after vaccination. In order to better understand the lack of association between immune response and clinical response, we have examined additional aspects of the AFP immune response in patients. Here, we have characterized the cell surface phenotype of circulating AFP tetramer-positive CD8 T cells and assessed AFP-specific CD4 function. Before vaccination, HCC subjects had increased frequencies of circulating AFP-specific CD8 T cells with a range of naïve, effector, central and effector memory phenotypes. Several patients had up-regulated activation markers. A subset of patients was assessed for phenotypic changes pre- and post-vaccination, and evidence for complete differentiation to effector or memory phenotype was lacking. CD8 phenotypic and cytokine responses did not correlate with level of patient serum AFP antigen (between 74 and 463,040 ng/ml). Assessment of CD4+ T cell responses by ELISPOT and multi-cytokine assay did not identify any spontaneous CD4 T cell responses to this secreted protein. These data indicate that there is an expanded pool of partially differentiated AFP-specific CD8 T cells in many of these HCC subjects, but that these cells are largely non-functional, and that a detectable CD4 T cell response to this secreted oncofetal antigen is lacking.
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http://dx.doi.org/10.1007/s00262-007-0337-9DOI Listing
December 2007

Surveillance of the eye and vision in clinical trials of CP-675,206 for metastatic melanoma.

Am J Ophthalmol 2007 Jun 16;143(6):958-969. Epub 2007 Apr 16.

Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, California 90095, USA.

Purpose: To determine the ocular safety of CP-675,206 (Pfizer, New York, New York, USA), a fully human anti-cytotoxic T lymphocyte-associated antigen 4 monoclonal antibody in clinical trials of immunotherapy of metastatic melanoma.

Design: Prospective, nonrandomized study of the eye and vision in phase I/II clinical trials of CP-675,206 in metastatic melanoma conducted at the University of California, Los Angeles.

Methods: Patients with regional or distant metastatic melanoma were enrolled in phase I/II clinical trials evaluating the safety and antitumor efficacy of CP-675,206 alone or in combination with melanoma antigen peptide-pulsed dendritic cell vaccines. Ophthalmic evaluation was performed at the onset of CP-675,206 immunotherapy (baseline evaluation), two months or more after the onset of CP-675,206 immunotherapy (end-study evaluation), and at two- to three-month intervals thereafter in patients who continued to receive CP-675,206 immunotherapy (poststudy evaluation). Baseline and end-study evaluations included comprehensive ophthalmic examination, psychophysical and electrophysiologic visual function assessment, fundus photography, fluorescein angiography, and visual function assessment.

Results: Twenty patients with metastatic melanoma arising from the skin, mucosa, eye, or unknown site were evaluated. Systemic toxicity attributed to CP-675,206 included dermatologic manifestations, diarrhea, and autoimmune hepatitis with panhypopituitarism. A subset of patients receiving CP-675,206 demonstrated antitumor efficacy with partial response or complete response of metastatic melanoma. Comparison of ophthalmic baseline with end-study evaluations in all 20 patients and limited-term poststudy evaluations showed no adverse effect of CP-675,206 immunotherapy on the eye or vision.

Conclusions: In this study, CP-675,206 immunotherapy for metastatic melanoma did not adversely affect the eye or vision.
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http://dx.doi.org/10.1016/j.ajo.2007.02.035DOI Listing
June 2007

NK and CD4 cells collaborate to protect against melanoma tumor formation in the brain.

J Immunol 2006 Dec;177(12):8448-55

Department of Surgery, Division of Neurosurgery, Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California-Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.

NK cells represent a potent immune effector cell type that have the ability to recognize and lyse tumors. However, the existence and function of NK cells in the traditionally "immune-privileged" CNS is controversial. Furthermore, the cellular interactions involved in NK cell anti-CNS tumor immunity are even less well understood. We administered non-Ag-loaded, immature dendritic cells (DC) to CD8alpha knockout (KO) mice and studied their anti-CNS tumor immune responses. DC administration induced dramatic antitumor immune protection in CD8alpha KO mice that were challenged with B16 melanoma both s.c. and in the brain. The CNS antitumor immunity was dependent on both CD4+ T cells and NK cells. Administration of non-Ag-loaded, immature DC resulted in significant CD4+ T cell and NK cell expansion in the draining lymph nodes at 6 days postvaccination, which persisted for 2 wk. Finally, DC administration in CD8alpha KO mice was associated with robust infiltration of CD4+ T cells and NK cells into the brain tumor parenchyma. These results represent the first demonstration of a potent innate antitumor immune response against CNS tumors in the absence of toxicity. Thus, non-Ag-loaded, immature DC administration, in the setting of CD8 genetically deficient mice, can induce dramatic antitumor immune responses within the CNS that surpass the effects observed in wild-type mice. Our results suggest that a better understanding of the cross-talk between DC and innate immune cells may provide improved methods to vaccinate patients with tumors located both systemically and within the CNS.
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http://dx.doi.org/10.4049/jimmunol.177.12.8448DOI Listing
December 2006

A phase I/II trial testing immunization of hepatocellular carcinoma patients with dendritic cells pulsed with four alpha-fetoprotein peptides.

Clin Cancer Res 2006 May;12(9):2817-25

Department of Medicine, Surgery and Immunology, Hillman Cancer Center, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213, USA.

Alpha-fetoprotein (AFP) is a self protein expressed by fetal liver at high levels, but is transcriptionally repressed at birth. AFP is up-regulated in hepatocellular carcinomas, and patients with active disease could have plasma levels as high as 1 mg/mL. We previously identified four immunodominant HLA-A*0201-restricted peptides [hAFP(137-145) (PLFQVPEPV), hAFP(158-166) (FMNKFIYEI), hAFP(325-334) (GLSPNLNRFL), and hAFP(542-550) (GVALQTMKQ)] derived from human AFP that could stimulate specific T cell responses in healthy donor peripheral blood lymphocytes in vitro. We conducted a phase I/II clinical trial in which HLA-A*0201 patients with AFP-positive hepatocellular carcinoma were immunized with three biweekly intradermal vaccinations of the four AFP peptides pulsed onto autologous dendritic cells (DC). DCs were prepared from adherent peripheral blood mononuclear cells cultured with granulocyte-macrophage colony-stimulating factor and interleukin-4 for 7 days. Sixteen subjects were enrolled and 10 were treated. Peripheral blood lymphocytes were isolated from these patients before, during, and after AFP peptide/DC immunization and were tested ex vivo with MHC tetramer and IFNgamma ELISPOT analysis. Six of 10 subjects expanded statistically significant levels of AFP-specific T cells postvaccine to at least one peptide by MHC tetramer. Also, 6 of 10 subjects increased IFNgamma producing AFP-specific T cell responses to at least one of the peptides postvaccination, by ELISPOT. We conclude that the human T cell repertoire is capable of responding to the AFP self antigen after the administration of AFP peptide-pulsed DC even in an environment of high circulating levels of this oncofetal antigen.
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http://dx.doi.org/10.1158/1078-0432.CCR-05-2856DOI Listing
May 2006