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B-cell malignancies can potentially be cured by CD19 chimeric antigen receptor (CAR) T-cell therapy. Although clinical response rates can be up to 93% in acute lymphoblastic leukemia, treatment-related antigen loss and lack of therapeutic persistence contribute to disease relapse. These shortcomings of current CAR T-cell therapy indicate the need for biologically relevant target selection and for improving the efficacy and persistence of the CAR T cells, which we have addressed by developing a novel B-cell activating factor receptor (BAFF-R) CAR T-cell therapy with improved therapeutic persistence. BAFF-R is a B-cell survival receptor and highly expressed in B-cell malignancies. We developed a prototype CAR T cell that efficiently and specifically eliminated BAFF-R expressing human B-cell tumors in several xenogeneic mouse models, including models of CD19 antigen loss. We proceeded with translational development and validation of BAFF-R CAR T cells produced under current good manufacturing practices (cGMP). cGMP-grade BAFF-R CAR T cells underwent in vitro and in vivo validation in established models to confirm that the potency and efficacy of our original research modeling was replicated. Food and Drug Administration required release testing was performed to ensure our BAFF-R CAR T cells meet specifications for new drug products. Completing and exceeding these requirements, the data fully support the initiation of a first-in-human Phase 1 trial for BAFF-R-positive relapsed/refractory (r/r) B-ALL. [ABSTRACT FROM AUTHOR]

T-cell tolerance is a major obstacle to successful cancer immunotherapy; thus, developing strategies to break immune tolerance is a high priority. Here we show that expression of the E3 ubiquitin ligase Grail is upregulated in CD8+ T cells that have infiltrated into transplanted lymphoma tumours, and Grail deficiency confers long-term tumour control. Importantly, therapeutic transfer of Grail-deficient CD8+ T cells is sufficient to repress established tumours. Mechanistically, loss of Grail enhances anti-tumour reactivity and functionality of CD8+ T cells. In addition, Grail-deficient CD8+ T cells have increased IL-21 receptor (IL-21R) expression and hyperresponsiveness to IL-21 signalling as Grail promotes IL-21R ubiquitination and degradation. Moreover, CD8+ T cells isolated from lymphoma patients express higher levels of Grail and lower levels of IL-21R, compared with CD8+ T cells from normal donors. Our data demonstrate that Grail is a crucial factor controlling CD8+ T-cell function and is a potential target to improve cytotoxic T-cell activity. [ABSTRACT FROM AUTHOR]

A phase II study was performed to evaluate the efficacy of hyper-fractionated cyclophosphamide, vincristine, pegylated liposomal doxorubicin and dexamethasone alternating with methotrexate/cytarabine ( HCVIDD/ MA) in patients with newly diagnosed peripheral T-cell lymphoma ( PTCL), excluding ALK-positive anaplastic large cell lymphoma. Fifty-three patients were enrolled. Treatment was planned for up to 8 cycles but only 9% of patients received more than 6 cycles due primarily to disease progression ( n = 13) or prolonged thrombocytopenia ( n = 12). The overall response rate was 66% with a complete response rate of 57%. Median progression-free survival ( PFS) was 7·5 months. With a median follow-up of 7·6 years, 5-year PFS and overall survival ( OS) were 21% and 48%, respectively. The patients with extranodal Natural Killer-cell lymphoma had a shorter PFS (median, 2·4 months) than other subtypes. Grade 3/4 anaemia, neutropenia and thrombocytopenia were observed in 66%, 74% and 79% of patients, respectively. Of note, 23% of patients discontinued therapy due to prolonged thrombocytopenia. In conclusion, HCVIDD/ MA for the first-line treatment of PTCL patients is associated with significant myelosuppression leading to poor treatment adherence, and the response and survival outcomes with this regimen are similar to standard CHOP. This study was registered at as # NCT00290433. [ABSTRACT FROM AUTHOR]

The role of B cells in T-cell priming is unclear, and the effects of B-cell depletion on immune responses to cancer vaccines are unknown. Although results from some mouse models suggest that B cells may inhibit induction of T cell–dependent immunity by competing with antigen-presenting cells for antigens, skewing T helper response toward a T helper 2 profile and/or inducing T-cell tolerance, results from others suggest that B cells are necessary for priming as well as generation of T-cell memory. We assessed immune responses to a well-characterized idiotype vaccine in individuals with severe B-cell depletion but normal T cells after CD20-specific antibody–based chemotherapy of mantle cell lymphoma in first remission. Humoral antigen- and tumor-specific responses were detectable but delayed, and they correlated with peripheral blood B-cell recovery. In contrast, vigorous CD4+ and CD8+ antitumor type I T-cell cytokine responses were induced in most individuals in the absence of circulating B cells. Analysis of relapsing tumors showed no mutations or change in expression of target antigen to explain escape from therapy. These results show that severe B-cell depletion does not impair T-cell priming in humans. Based on these results, it is justifiable to administer vaccines in the setting of B-cell depletion; however, vaccine boosts after B-cell recovery may be necessary for optimal humoral responses. [ABSTRACT FROM AUTHOR]

Background: The desired outcome of cancer vaccination is to induce a potent T cell response which can specifically recognize and eliminate autologous tumor cells in vivo. Accordingly, immunological assays that demonstrate recognition of native tumor cells (tumor-specific) may be more clinically relevant than assays that demonstrate recognition of tumor protein or peptide (antigen-specific). Methods: Towards this goal, we adapted the IFN-? ELISPOT assay to measure immune responses against autologous primary tumor cells in vaccinated cancer patients. As a model system to develop the assay, we utilized peripheral blood mononuclear cells (PBMC) directly isolated from follicular lymphoma patients vaccinated with tumor-derived idiotype protein. Results: After optimizing several variables, we demonstrated that the modified IFN-γ ELISPOT assay could be used to reliably and reproducibly determine the tumor-reactive T cell frequency in the PBMC of these patients. The precursor frequency of tumor-reactive T cells was significantly higher in the postvaccine PBMC, compared with prevaccine samples in all patients tested. Furthermore, the specificity of these T cells was established by the lack of reactivity against autologous normal B cells. Conclusions: These results demonstrate the feasibility of quantitating tumor-specific T cell responses when autologous, primary tumor cells are available as targets. [ABSTRACT FROM AUTHOR]

In vitro priming of T cells with dendritic cells (DC) pulsed with clinically relevant, but weak antigens such as tumor idiotype (Id), is an attractive strategy to generate tumor-specific T lymphocytes. In order to enhance the specific antitumor effect of allogeneic stem cell grafts, we investigated whether induction of tumor specific T cells using autologous DC pulsed with patient's myeloma Id could be maintained and potentiated by in vitro priming. For induction of T cells, DC (5 × 10[sup 5]/well) were cultured with autologous nonadherent cells (DONA) (5 × 10[sup 6]/well) and antigen (TT10 ug/ml, KLH 100 ug/ml and Id 100 ug/ml). The T cells were restimulated every 8-10 days with the corresponding antigen and autologous DC. After 2-4 cycles of in vitro priming, the T cells were compared with nonadherent cells obtained after 2 h attachment on day 0 (DoNA) for antigen-specific cytokine production. In vitro primed T cells (2-4 cycles of stimulation with Ag and DC) showed significant antigen-specific cytokine responses (IFN-γ, TNF-α, GM-CSF) to TT. Similarly, in vitro priming of T cells to Id-pulsed DC resulted in marked increases in cytokine production for both myeloma Id proteins tested. These data suggest that multiple in vitro immunization using DC could be beneficial in generating tumor specific T cells from normal donor PBMC, which may be used for adoptive immunotherapy (e.g. "tumor-specific" donor lymphocyte infusion) of B cell malignancies. In vitro immunization may also offer an alternative to immunization of healthy stem cell transplant donors with tumor antigen. [ABSTRACT FROM AUTHOR]

B-cell malignancy-derived Ig may be considered a model tumor antigen for vaccine development. However, as a non-immunogenic self antigen, it must also be first rendered immunogenic by chemical or genetic fusion to carriers which enable the induction of protective antitumor immunity in murine tumor models. Our group has demonstrated that active immunizations of human patients with idiotypic vaccines elicited antigen-specific CD8[sup+] T-cell responses and antitumor effects. Several alternative preclinical strategies to develop vaccines have been previously reported, including fusion of tumor idiotype-derived single chain Fv with cytokines and immunogenic peptides. On the other hand, we have recently explored a different approach in which the model antigen is rendered immunogenic in mice by genetically fusing it to a chemokine moiety. Administration of these vaccines as fusion proteins or naked DNA vaccines may allow efficient targeting of antigen-presenting cells in vivo. Potent antitumor immunity was dependent on the generation of specific anti-idiotypic antibodies and both CD4[sup+] and CD8[sup+] effector T cells. We propose that chemoline fusion may represent a novel, general strategy for formulating existing or newly identified tumor and HIV antigens into vaccines for cancer and AIDS, respectively, which elicit potent CD8[sup+] T-cell immunity. [ABSTRACT FROM AUTHOR]

The authors comment on the results of a multicenter phase II study wherein patients with castration-resistant metastatic prostate cancer received the standard three doses of sipuleucel to determine changes in immune cell infiltrates in the paired tumor tissues. They describe the amount of infiltrating T cells found and the limitations of the study. They also discuss the implications of the study for the mechanism of action of sipuleucel-T.

Optimal expansion protocols for adoptive human T-cell therapy often include interleukin (IL)-15; however, the mechanism by which IL-15 improves thein vivoantitumor effect of T cells remains to be elucidated. Using human T cells generated from HLA-A2+ donors against novel T-cell epitopes derived from the human U266 myeloma cell line Ig light chain V-region (idiotype) as a model, we found that T cells cultured with IL-15 provided superior resistance to tumor growthin vivo, compared with IL-2, after adoptive transfer into immunodeficient hosts. This effect of IL-15 was associated with delayed/reversed senescence in tumor antigen-specific memory CD8+T cells mediated through downregulation of P21WAF1, P16INK4a, and P53 expression. Compared to IL-2, IL-15 stimulation dramatically activated JAK3-STAT5 signaling and inhibited the expression of DNA damage genes. Thus, our study elucidates a new mechanism for IL-15 in the regulation of STAT signaling pathways and CD8+T-cell senescence. [ABSTRACT FROM AUTHOR]

The B-cell receptor (BCR) expressed by a clonal B cell tumor is a tumor specific antigen (idiotype). However, the T-cell epitopes within human BCRs which stimulate protective immunity still lack detailed characterization. In this study, we identified 17 BCR peptide-specific CD4+T-cell epitopes derived from BCR heavy and light chain variable region sequences. Detailed analysis revealed these CD4+T-cell epitopes stimulated normal donors' and patients' Th1 CD4+T cells to directly recognize the autologous tumors by secretion of IFNγ, indicating the epitopes are processed and presented by tumor cells. One BCR peptide-specific CD4+T cell line was also cytotoxic and lysed autologous tumor cells through the perforin pathway. Sequence analysis of the epitopes revealed that 10 were shared by multiple primary patients' tumors, and 16 had the capacity to bind to more than one HLA DRB1 allele. T cells stimulated by shared epitopes recognized primary tumors expressing the same sequences on multiple HLA DRB1 alleles. In conclusion, we identified 17 BCR-derived CD4+T-cell epitopes with promiscuous HLA DRB1 binding affinity that are shared by up to 36% of patients, suggesting a strategy to overcome the requirement for individual preparation of therapeutic agents targeting idiotype. [ABSTRACT FROM AUTHOR]

The clonotypic surface Ig receptor expressed by malignant B cells,idiotype,is a tumor-specific antigen and an attractive target for active immunotherapy.While Ab's specific for tumor idiotype have been well described in patients with B cell malignancies,the precise antigenic epitopes in human idiotype recognized by autologous T cells remain largely unknown.We report here that T cell lines generated from lymphoma patients actively immunized with idiotype protein specifically recognized multiple,unique immunodominant epitopes in autologous tumor idiotype.Synthetic peptides corresponding to hypervariable,but not frame- work,regions of Ig heavy chain specifically stimulated CD4 +and CD8 +T cells to proliferate and secrete proinf lammatory cytokines in an MHC-associated manner.Detailed analysis revealed a minimal determi- nant of an immunodominant epitope,comprising critical residues at the amino terminus that may be a prod- uct of somatic hypermutation.Association of idiotype-specific T cell responses with previously documented molecular remissions in idiotype-vaccinated patients suggests that the newly identified T cell epitopes may be clinically relevant.Such antigenic epitopes may serve as candidates for novel peptide-vaccine strategies,and as tools to selectively expand tumor antigen --specific T cells for adoptive immunotherapy and for monitoring T cell immunity in vaccinated patients. [ABSTRACT FROM AUTHOR]

Abstract: Success of an immunotherapy for cancer often depends on the critical balance of T helper 1 (Th1) and T helper 2 (Th2) responses driven by antigen presenting cells, specifically dendritic cells (DCs). Th1-driven cytotoxic T cell (CTL) responses are key to eliminating tumor cells. It is well established that CpG oligonucleotides (ODN), a widely studied Toll-like receptor 9 (TLR9) agonist, used to enhance Th1 response, also induces high levels of the anti-inflammatory, Th2-promoting cytokine IL10, which could dampen the resulting Th1 response. Biomaterials-based immunomodulatory strategies that can reduce IL10 production while maintaining IL12 levels during CpG delivery could further enhance the Th1/Th2 cytokine balance and improve anti-tumor immune response. Here we report that dual-delivery of IL10-silencing siRNA along with CpG ODN to the same DCs using pathogen-mimicking microparticles (PMPs), significantly enhances their Th1/Th2 cytokine ratio through concurrent inhibition of CpG-induced IL10 production. Co-delivery of poly(I:C), a TLR3 agonist had only minor effects on IL10 levels. Further, simultaneous immunotherapy with CpG ODN and IL10 siRNA enhanced immune protection of an idiotype DNA vaccine in a prophylactic murine model of B cell lymphoma whereas co-delivery of poly(I:C) and CpG did not enhance protection. These results suggest that PMPs can be used to precisely modulate TLR ligand-mediated immune-stimulation in DCs, through co-delivery of cytokine-silencing siRNAs and thereby boost antitumor immunity. [Copyright &y& Elsevier]

Current cancer vaccines induce tumor-specific T cell responses without sustained tumor regression because immunosuppressive elements within the tumor induce exhaustion of effector T cells and infiltration of immune-suppressive regulatory T cells (Tregs). Therefore, much effort has been made to generate agonistic Abs targeting members of the TNFR superfamily, such as OX40, 4-1BB, and GITR, expressed on effector T cells and Tregs, to reinvigorate T cell effector function and block Treg-suppressive function. In this article, we describe the development of a panel of anti-human OX40 agonistic mouse mAbs that could promote effector CD4+ and CD8+ T cell proliferation, inhibit the induction of CD4+ IL-10 -producing type 1 regulatory T cells, inhibit the expansion of ICOS+IL-10+ Tregs, inhibit TGF-β-induced FOXP3 expression on naive CD4+ T cells, and block natural Treg-suppressive function. We humanized two anti-human OX40 mAb clones, and they retained the potency of their parental clones. These Abs should provide broad opportunities for potential combination therapy to treat a wide realm of cancers and preventative vaccines against infectious diseases. [ABSTRACT FROM AUTHOR]

Dickkopf-1 (DKK1), broadly expressed in myeloma cells but highly restricted in normal tissues, together with its functional roles as an osteoblast formation inhibitor, may be an ideal target for immunotherapy in myeloma. Our previous studies have shown that DKK1 (peptide)-specific CTLs can effectively lyse primary myeloma cells in vitro. The goal of this study was to examine whether DKK1 can be used as a tumor vaccine to elicit DKK1-specific immunity that can control myeloma growth or even eradicate established myeloma in vivo. We used DKK1-DNA vaccine in the murine MOPC-21 myeloma model, and the results clearly showed that active vaccination using the DKK1 vaccine not only was able to protect mice from developing myeloma, but it was also therapeutic against established myeloma. Furthermore, the addition of CpG as an adjuvant, or injection of B7H1-blocking or OX40-agonist Abs, further enhanced the therapeutic effects of the vaccine. Mechanistic studies revealed that DKK1 vaccine elicited a strong DKK1- and tumor-specific CD4+ and CD8+ immune responses, and treatment with B7H1 or OX40 Abs significantly reduced the numbers of IL-10-expressing and Foxp3+ regulatory T cells in vaccinated mice. Thus, our studies provide strong rationale for targeting DKK1 for immunotherapy of myeloma patients. [ABSTRACT FROM AUTHOR]

Abstract: Patients with malignant non-Hodgkin''s lymphomas (NHL) of B-cell lineages relapse despite initial anti-tumor response to chemotherapy or antibody treatments. Failure to eliminate the tumor is often because of inadequate priming, low cell numbers and suboptimal phenotype of effector T cells. Here we describe a new biomaterial-based controlled-release paradigm to treat weakly immunogenic NHLs by in-situ amplifying the number of functional, antigen-specific T-helper 1 (Th1) cells following immunotherapy. An injectable, synthetic immune priming center (sIPC) consisting of an in-situ crosslinking, chemokine-carrying hydrogel and both DNA- and siRNA dual-loaded microparticles, is reported. This sIPC chemo attracts a large number of immature dendritic cells (DCs) at the site of administration and efficiently co-delivers both DNA antigens and interleukin-10 (IL10)-silencing siRNA to those cells. Using a murine model of A20 B cell lymphoma, we demonstrate that combination of DNA-antigen delivery and IL10 silencing, synergistically activate recruited immature DCs and cause a strong shift towards Th1 response while suppressing Th2 and Th17 cytokines. sIPC-based immunotherapy showed 45% more CD8+ cytotoxic T cell (CTL) response and 53% stronger CD4+ CTL activity compared to naked DNA vaccine. In addition, in-vivo sIPC immunization induced significant protection (p <0.01) against subsequent tumor challenge. Such a multi-modal, injectable system that simultaneously delivers chemokines, siRNA and DNA antigens to DCs marks a new approach to in-situ priming and modulation during immunotherapy and could provide effective vaccination strategies against cancers and infectious diseases. [Copyright &y& Elsevier]

Abstract: Adoptive therapy with antigen-specific T cells is a promising approach for the treatment of infectious diseases and cancer. However, cloning of antigen-specific T cells by the traditional approach of limiting dilution is a time-consuming, laborious, and inefficient process. Here, we describe a novel flow cytometric strategy for rapid isolation of human tumor antigen-specific T-cell clones by using T-cell receptor (TCR) Vβ antibodies in combination with carboxyfluorescein succinimidyl ester (CFSE)-based proliferation assay. The CFSE dilution following antigen stimulation identified proliferating antigen-specific T cells, and the TCRVβ antibodies allowed distinguishing T cells at the clonal level from a heterogeneous T-cell population. This method of TCRVβ/CFSE dilution was used for the isolation of four different human lymphoma and melanoma-specific CD4+ and CD8+ T-cell clones reactive against defined and undefined tumor antigens. Isolated tumor-specific T-cell clones could be expanded to large numbers ex vivo while maintaining phenotype, function, and tumor antigen specificity. The method was simple, efficient, and reproducible, and may have potential application for the development of adoptive immunotherapeutic strategies. [Copyright &y& Elsevier]