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1.  A fully human chimeric antigen receptor with potent activity against cancer cells but reduced risk for off-tumor toxicity 
Oncotarget  2015;6(25):21533-21546.
Chimeric antigen receptors (CARs) can redirect T cells against antigen-expressing tumors in an HLA-independent manner. To date, various CARs have been constructed using mouse single chain antibody variable fragments (scFvs) of high affinity that are immunogenic in humans and have the potential to mediate “on-target” toxicity. Here, we developed and evaluated a fully human CAR comprised of the human C4 folate receptor-alpha (αFR)-specific scFv coupled to intracellular T cell signaling domains. Human T cells transduced to express the C4 CAR specifically secreted proinflammatory cytokine and exerted cytolytic functions when cultured with αFR-expressing tumors in vitro. Adoptive transfer of C4 CAR T cells mediated the regression of large, established human ovarian cancer in a xenogeneic mouse model. Relative to a murine MOv19 scFv-based αFR CAR, C4 CAR T cells mediated comparable cytotoxic tumor activity in vitro and in vivo but had lower affinity for αFR protein and exhibited reduced recognition of normal cells expressing low levels of αFR. Thus, T cells expressing a fully human CAR of intermediate affinity can efficiently kill antigen-expressing tumors in vitro and in vivo and may overcome issues of transgene immunogenicity and “on-target off-tumor” toxicity that plague trials utilizing CARs containing mouse-derived, high affinity scFvs.
PMCID: PMC4673284  PMID: 26101914
folate receptor alpha; chimeric antigen receptor; adoptive immunotherapy; ovarian cancer; T cells
2.  CD137 accurately identifies and enriches for naturally-occurring tumor-reactive T cells in tumor 
Up-regulation of CD137 (4-1BB) on recently activated CD8+ T-cells has been used to identify rare viral or tumor antigen-specific T-cells from peripheral blood. Here, we evaluated the immunobiology of CD137 in human cancer and the utility of a CD137-positive separation methodology for the identification and enrichment of fresh tumor-reactive tumor-infiltrating lymphocytes (TILs) or tumor-associated lymphocytes (TAL) from ascites for use in adoptive immunotherapy.
Experimental Design
TILs from resected ovarian cancer or melanoma were measured for surface CD137expression directly or after overnight incubation in the presence of tumor cells and homeostatic cytokines. CD137pos TILs were sorted and evaluated for anti-tumor activity in vitro and in vivo.
Fresh ovarian TILs and TALs naturally expressed higher levels of CD137 than circulating T-cells. An HLA-dependent increase in CD137 expression was observed following incubation of fresh enzyme-digested tumor or ascites in IL-7 and IL-15 cytokines, but not IL-2. Enriched CD137pos TILs, but not PD-1pos or PD-1neg CD137neg cells, possessed autologous tumor-reactivity in vitro and in vivo. In melanoma studies, all MART-1-specific CD8+ TILs up-regulated CD137 expression after incubation with HLA-matched, MART-expressing cancer cells and antigen-specific effector function was restricted to the CD137pos subset in vitro. CD137pos TILs also mediated superior anti-tumor effects in vivo, compared to CD137neg TILs.
Our findings reveal a role for the TNFR-family member CD137 in the immunobiology of human cancer where it is preferentially expressed on tumor-reactive subset of TILs, thus rationalizing its agonistic engagement in vivo and its use in TIL selection for adoptive immunotherapy trials.
PMCID: PMC3947326  PMID: 24045181
Tumor infiltrating lymphocyte (TIL); CD137 (4-1BB); Adoptive Immunotherapy; Tumor antigen; Enrichment
3.  In vivo persistence, tumor localization and anti-tumor activity of CAR engineered T cells is enhanced by costimulatory signaling through CD137 (4-1BB) 
Cancer research  2011;71(13):4617-4627.
Human T cells engineered to express a chimeric antigen receptor (CAR) specific for folate receptor-alpha (FRα) have shown robust anti-tumor activity against epithelial cancers in vitro but not in the clinic due to their inability to persist and home to tumor in vivo. In this study, CARs were constructed containing a FRα-specific scFv (MOv19) coupled to the T cell receptor CD3ζ chain signaling module alone (MOv19-ζ) or in combination with the CD137 (4-1BB) costimulatory motif in tandem (MOv19-BBζ). Primary human T cells transduced to express conventional MOv19-ζ or costimulated MOv19-BBζ CARs secreted various proinflammatory cytokines and exerted cytotoxic function when cocultured with FRα+ tumor cells in vitro. However, only transfer of human T cells expressing the costimulated MOv19-BBζ CAR mediated tumor regression in immunodeficient mice bearing large, established FRα+ human cancer. MOv19-BBζ CAR T cell infusion mediated tumor regression in models of metastatic intraperitoneal, subcutaneous, and lung-involved human ovarian cancer. Importantly, tumor response was associated with the selective survival and tumor localization of human T cells in vivo and was only observed in mice receiving costimulated MOv19-BBζ CAR T cells. T cell persistence and anti-tumor activity were primarily antigen-driven; however, antigen-independent CD137 signaling by CAR did improve T cell persistence but not anti-tumor activity in vivo. Our results show that anti-FRα CAR outfitted with CD137 costimulatory signaling in tandem overcome issues of T cell persistence and tumor localization that limit the conventional FRα T cell targeting strategy to provide potent antitumor activity in vivo.
PMCID: PMC4140173  PMID: 21546571
4.  Chimeric NKG2D CAR-Expressing T Cell-Mediated Attack of Human Ovarian Cancer Is Enhanced by Histone Deacetylase Inhibition 
Human Gene Therapy  2013;24(3):295-305.
NKG2D ligands (NKG2DLs) are widely expressed on ovarian cancers to various degrees, making them attractive targets for immunotherapy. Here, we applied a chimeric antigen receptor (CAR) approach for the targeting of NKG2DLs expressed on human ovarian cancer cells and evaluated the impact of pharmacological upregulation of NKG2DLs on immune recognition. Various NKG2DLs, including MICA/B and ULBP-1, -2, -3, and -4, were expressed at various levels on the surface of all established ovarian cancer cell lines and primary ovarian cancer samples tested. To redirect human T cells against NKG2DLs, an NKG2DL-specific CAR was generated by fusing the extracellular domain of the NKG2D receptor to the 4-1BB costimulatory and CD3-ζ chain signaling domains. In vitro expansion of chimeric NKG2D CAR T cells was delayed compared with untransduced T cells and control CAR T cells; the likely result of fratricide among activated T cells expressing NKG2DLs. However, NKG2D CAR T cells did expand and were selectively enriched during prolonged culture. In coculture, CD4+ and CD8+ NKG2D CAR T cells specifically recognized and killed NKG2DL-expressing ovarian cancer cell lines but not NKG2DL-negative cells. Notably, pretreatment of ovarian cancer cells expressing moderate to low levels of NKG2DLs with the histone deacetylase inhibitor sodium valproate (VPA) upregulated NKG2DL cell surface expression and consequently enhanced their immune recognition by chimeric NKG2D CAR T cells. Our results demonstrate that VPA-induced upregulation of NKG2DL expression enhances the immune recognition of ovarian cancer cells by engineered NKG2D CAR T cells, and rationalizes the use of VPA in combination with NKG2DL-targeted immunotherapy in ovarian cancer.
Song and colleagues target NKG2D ligands (NGK2DLs) expressed on various human ovarian cancer cells, using a chimeric antigen receptor (CAR) approach. NGK2DL-specific CAR T cells selectively kill NKG2DL-expressing cells, and this immune recognition is enhanced by increasing surface NGK2DL expression, using a histone deacetylase inhibitor.
PMCID: PMC3609608  PMID: 23297870
5.  Finding a needle in a haystack 
Oncoimmunology  2013;2(12):e27184.
We have recently identified tumor necrosis factor receptor superfamily, member 9 (TNFRSF9, best known as CD137 or 4–1BB) as a biomarker of tumor-reactive T cells naturally occurring in cancer patients, and developed a rapid, accurate system to comprehensively isolate lymphocytes with tumor-rejecting properties from human biopsies. Our findings reveal a previously unappreciated role for CD137, a co-stimulatory TNFR family member, in the immunobiology of human cancer.
PMCID: PMC3914380  PMID: 24501691
4-1BB; CD137, adoptive immunotherapy, enrichment, tumor-associated antigens, tumor-infiltrating lymphocytes
6.  Optimizing parameters for clinical-scale production of high IL-12 secreting dendritic cells pulsed with oxidized whole tumor cell lysate 
Dendritic cells (DCs) are the most potent antigen-presenting cell population for activating tumor-specific T cells. Due to the wide range of methods for generating DCs, there is no common protocol or defined set of criteria to validate the immunogenicity and function of DC vaccines.
Monocyte-derived DCs were generated during 4 days of culture with recombinant granulocyte-macrophage colony stimulating factor and interleukin-4, and pulsed with tumor lysate produced by hypochlorous acid oxidation of tumor cells. Different culture parameters for clinical-scale DC preparation were investigated, including: 1) culture media; 2) culture surface; 3) duration of activating DCs with lipopolysaccharide (LPS) and interferon (IFN)-gamma; 4) method of DC harvest; and 5) cryomedia and final DC product formulation.
DCs cultured in CellGenix DC media containing 2% human AB serum expressed higher levels of maturation markers following lysate-loading and maturation compared to culturing with serum-free CellGenix DC media or AIM-V media, or 2% AB serum supplemented AIM-V media. Nunclon™Δ surface, but not Corning® tissue-culture treated surface and Corning® ultra-low attachment surface, were suitable for generating an optimal DC phenotype. Recombinant trypsin resulted in reduced major histocompatibility complex (MHC) Class I and II expression on mature lysate-loaded DCs, however presentation of MHC Class I peptides by DCs was not impaired and cell viability was higher compared to cell scraping. Preservation of DCs with an infusible cryomedia containing Plasma-Lyte A, dextrose, sodium chloride injection, human serum albumin, and DMSO yielded higher cell viability compared to using human AB serum containing 10% DMSO. Finally, activating DCs for 16 hours with LPS and IFN-γ stimulated robust mixed leukocyte reactions (MLRs), and high IL-12p70 production in vitro that continued for 24 hours after the cryopreserved DCs were thawed and replated in fresh media.
This study examined criteria including DC phenotype, viability, IL-12p70 production and the ability to stimulate MLR as metrics of whole oxidized tumor lysate-pulsed DC immunogenicity and functionality. Development and optimization of this unique method is now being tested in a clinical trial of autologous oxidized tumor lysate-pulsed DC in clinical-scale in recurrent ovarian, primary peritoneal or fallopian tube cancer (NCT01132014).
PMCID: PMC3283529  PMID: 22082029
7.  Engineered artificial antigen presenting cells facilitate direct and efficient expansion of tumor infiltrating lymphocytes 
Development of a standardized platform for the rapid expansion of tumor-infiltrating lymphocytes (TILs) with anti-tumor function from patients with limited TIL numbers or tumor tissues challenges their clinical application.
To facilitate adoptive immunotherapy, we applied genetically-engineered K562 cell-based artificial antigen presenting cells (aAPCs) for the direct and rapid expansion of TILs isolated from primary cancer specimens.
TILs outgrown in IL-2 undergo rapid, CD28-independent expansion in response to aAPC stimulation that requires provision of exogenous IL-2 cytokine support. aAPCs induce numerical expansion of TILs that is statistically similar to an established rapid expansion method at a 100-fold lower feeder cell to TIL ratio, and greater than those achievable using anti-CD3/CD28 activation beads or extended IL-2 culture. aAPC-expanded TILs undergo numerical expansion of tumor antigen-specific cells, remain amenable to secondary aAPC-based expansion, and have low CD4/CD8 ratios and FOXP3+ CD4+ cell frequencies. TILs can also be expanded directly from fresh enzyme-digested tumor specimens when pulsed with aAPCs. These "young" TILs are tumor-reactive, positively skewed in CD8+ lymphocyte composition, CD28 and CD27 expression, and contain fewer FOXP3+ T cells compared to parallel IL-2 cultures.
Genetically-enhanced aAPCs represent a standardized, "off-the-shelf" platform for the direct ex vivo expansion of TILs of suitable number, phenotype and function for use in adoptive immunotherapy.
PMCID: PMC3162913  PMID: 21827675
8.  Distinct Expression Levels and Patterns of Stem Cell Marker, Aldehyde Dehydrogenase Isoform 1 (ALDH1), in Human Epithelial Cancers 
PLoS ONE  2010;5(4):e10277.
Aldehyde dehydrogenase isoform 1 (ALDH1) has been proved useful for the identification of cancer stem cells. However, our knowledge of the expression and activity of ALDH1 in common epithelial cancers and their corresponding normal tissues is still largely absent. Therefore, we characterized ALDH1 expression in 24 types of normal tissues and a large collection of epithelial tumor specimens (six cancer types, n = 792) by immunohistochemical staining. Using the ALDEFUOR assay, ALDH1 activity was also examined in 16 primary tumor specimens and 43 established epithelial cancer cell lines. In addition, an ovarian cancer transgenic mouse model and 7 murine ovarian cancer cell lines were analyzed. We found that the expression levels and patterns of ALDH1 in epithelial cancers are remarkably distinct, and they correlate with their corresponding normal tissues. ALDH1 protein expression levels are positively correlated with ALDH1 enzymatic activity measured by ALDEFLUOR assay. Long-term in vitro culture doesn't significantly affect ALDH1 activity in epithelial tumor cells. Consistent with research on other cancers, we found that high ALDH1 expression is significantly associated with poor clinical outcomes in serous ovarian cancer patients (n = 439, p = 0.0036). Finally, ALDHbr tumor cells exhibit cancer stem cell properties and are resistant to chemotherapy. As a novel cancer stem cell marker, ALDH1 can be used for tumors whose corresponding normal tissues express ALDH1 in relatively restricted or limited levels such as breast, lung, ovarian or colon cancer.
PMCID: PMC2858084  PMID: 20422001
9.  T Cell Costimulation through CD28 Depends on Induction of the Bcl-xγ Isoform 
The molecular basis of CD28-dependent costimulation of T cells is poorly understood. Bcl-xγ is a member of the Bcl-x family whose expression is restricted to activated T cells and requires CD28-dependent ligation for full expression. We report that Bcl-xγ–deficient (Bcl-xγ−/−) T cells display defective proliferative and cytokine responses to CD28-dependent costimulatory signals, impaired memory responses to proteolipid protein peptide (PLP), and do not develop PLP-induced experimental autoimmune encephalomyelitis (EAE). In contrast, enforced expression of Bcl-xγ largely replaces the requirement for B7-dependent ligation of CD28. These findings identify the Bcl-xγ cytosolic protein as an essential downstream link in the CD28-dependent signaling pathway that underlies T cell costimulation.
PMCID: PMC2194014  PMID: 12093873
Bcl-xγ; CD28; T cell; costimulation; EAE
10.  Modulation of LIGHT-HVEM Costimulation Prolongs Cardiac Allograft Survival 
LIGHT (TNFSF14), a tumor necrosis factor superfamily member expressed by activated T cells, binds to herpes virus entry mediator (HVEM) which is constitutively expressed by T cells and costimulates T cell activation in a CD28-independent manner. Given interest in regulating the effector functions of T cells in vivo, we examined the role of LIGHT-HVEM costimulation in a murine cardiac allograft rejection model. Normal hearts lacked LIGHT or HVEM mRNA expression, but allografts showed strong expression of both genes from day 3 after transplant, and in situ hybridization and immunohistology-localized LIGHT and HVEM to infiltrating leukocytes. To test the importance of LIGHT expression on allograft survival, we generated LIGHT−/− mice by homologous recombination. The mean survival of fully major histocompatibility complex–mismatched vascularized cardiac allografts in LIGHT−/− mice (10 days, P < 0.05) or cyclosporine A (CsA)-treated LIGHT+/+ mice (10 days, P < 0.05) was only slightly prolonged compared with LIGHT+/+ mice (7 days). However, mean allograft survival in CsA-treated LIGHT−/− allograft recipients (30 days) was considerably enhanced (P < 0.001) compared with the 10 days of mean survival in either untreated LIGHT−/− mice or CsA-treated LIGHT+/+ controls. Molecular analyzes showed that the beneficial effects of targeting of LIGHT in CsA-treated recipients were accompanied by decreased intragraft expression of interferon (IFN)-γ, plus IFN-γ–induced chemokine, inducible protein-10, and its receptor, CXCR3. Treatment of LIGHT+/+ allograft recipients with HVEM-Ig plus CsA also enhanced mean allograft survival (21 days) versus wild-type controls receiving HVEM-Ig (mean of 7 days) or CsA alone (P < 0.001). Our data suggest that T cell to T cell–mediated LIGHT/HVEM-dependent costimulation is a significant component of the host response leading to cardiac allograft rejection.
PMCID: PMC2193745  PMID: 11901205
transplantation; allograft rejection; T cell activation; costimulation; TNF superfamily

Results 1-10 (10)