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Purpose:Rocapuldencel-T is an autologous immunotherapy prepared from mature monocyte-derived dendritic cells (DC), coelectroporated with amplified tumor RNA plus CD40L RNA. This pivotal phase III trial was initiated to investigate the safety and efficacy of a combination therapy dosing regimen of Rocapuldencel-T plus sunitinib in patients with metastatic renal cell carcinoma (mRCC).Patients and Methods:Patients received either Rocapuldencel-T plus standard of care (SOC) or SOC treatment alone. The primary objective compared overall survival (OS) between groups. Secondary objectives included safety assessments, progression-free survival (PFS), and tumor responses based on RECIST 1.1 criteria. Exploratory analyses included immunologic assessments and correlates with OS.Results:Between 2013 and 2016, 462 patients were randomized 2:1, 307 to the combination group and 155 to the SOC group. Median OS in the combination group was 27.7 months [95% confidence interval (CI) 23.0–35.9] and 32.4 months (95% CI, 22.5–) in the SOC group HR of 1.10 (95% CI, 0.83–1.40). PFS was 6.0 months and 7.83 months for the combination and SOC groups, respectively [HR = 1.15 (95% CI, 0.92–1.44)]. The ORR was 42.7% (95% CI, 37.1–48.4) for the combination group and 39.4% (95% CI, 31.6–47.5) for the SOC group. Median follow up was 29 months (0.4–47.7 months). On the basis of the lack of clinical efficacy, the ADAPT trial was terminated on February 17, 2017. Immune responses were detected in 70% of patients treated with Rocapuldencel-T, and the magnitude of the immune response positively correlated with OS. In addition, we report the survival-predictive value of measuring IL-12 produced by the DC vaccine and the observation that high baseline numbers of T regulatory cells are associated with improved outcomes in DC-treated patients, but are associated with poor outcomes in patients receiving SOC treatment. No serious adverse events attributed to the study medication have been reported to date.Conclusions:Rocapuldencel-T did not improve OS in patients treated with combination therapy, although the induced immune response correlated with OS. Moreover, we identified two potential survival-predictive biomarkers for patients receiving DC based immunotherapy, IL-12 produced by the DC vaccine and higher numbers of T regulatory cells present in the peripheral blood of patients with advanced RCC.

subsequent standard of care treaments

Consort diagram

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ADAPT study group and participating centers

AGS-004 consists of matured autologous dendritic cells co-electroporated with in vitro transcribed RNA encoding autologous HIV antigens. In an open-label, single arm sub-study of AGS-004-003, AGS-004 was administered monthly to suppressed participants who started antiretroviral therapy (ART) during acute HIV infection. HIV-1 specific T cell responses were measured by multicolor flow cytometry after 3–4 doses. The frequency of resting CD4+ T-cell infection (RCI) was measured by quantitative viral outgrowth assay. Participants demonstrating increased immune response postvaccination were eligible for analytic treatment interruption (ATI). AGS-004 induced a positive immune response defined as ≥2-fold increase from baseline in the number of multifunctional HIV-1 specific CD28+/CD45RA− CD8+ effector/memory cytoxic T-lymphocytes (CTLs) in all six participants. All participants underwent ATI with rebound viremia at a median of 29 days. Immune correlates between time to viral rebound and the induction of effector CTLs were determined. Baseline RCI was low in most participants (0.043–0.767 IUPM). One participant had a >2-fold decrease (0.179–0.067 infectious units per million [IUPM]) in RCI at week 10. One participant with the lowest RCI had the longest ATI. AGS-004 dendritic cell administration increased multifunctional HIV-specific CD28+/CD45RA− CD8+ memory T cell responses in all participants, but did not permit sustained ART interruption. However, greater expansion of CD28−/CCR7−/CD45RA− CD8+ effector T cell responses correlated with a longer time to viral rebound. AGS-004 may be a useful tool to augment immune responses in the setting of latency reversal and eradication strategies.

The transmembrane protein CD83, expressed on APCs, B cells, and T cells, can be expressed as a soluble form generated by alternative splice variants and/or by shedding. Soluble CD83 (sCD83) was shown to be involved in negatively regulating the immune response. sCD83 inhibits T cell proliferation in vitro, supports allograft survival in vivo, prevents corneal transplant rejection, and attenuates the progression and severity of autoimmune diseases and experimental colitis. Although sCD83 binds to human PBMCs, the specific molecules that bind sCD83 have not been identified. In this article, we identify myeloid differentiation factor-2 (MD-2), the coreceptor within the TLR4/MD-2 receptor complex, as the high-affinity sCD83 binding partner. TLR4/MD-2 mediates proinflammatory signal delivery following recognition of bacterial LPSs. However, altering TLR4 signaling can attenuate the proinflammatory cascade, leading to LPS tolerance. Our data show that binding of sCD83 to MD-2 alters this signaling cascade by rapidly degrading IL-1R–associated kinase-1, leading to induction of the anti-inflammatory mediators IDO, IL-10, and PGE2 in a COX-2–dependent manner. sCD83 inhibited T cell proliferation, blocked IL-2 secretion, and rendered T cells unresponsive to further downstream differentiation signals mediated by IL-2. Therefore, we propose the tolerogenic mechanism of action of sCD83 to be dependent on initial interaction with APCs, altering early cytokine signal pathways and leading to T cell unresponsiveness.

Purpose: Rocapuldencel-T is an autologous immunotherapy prepared from mature monocyte-derived dendritic cells (DC), coelectroporated with amplified tumor RNA plus CD40L RNA. This pivotal phase III trial was initiated to investigate the safety and efficacy of a combination therapy dosing regimen of Rocapuldencel-T plus sunitinib in patients with metastatic renal cell carcinoma (mRCC). Patients and Methods: Patients received either Rocapuldencel-T plus standard of care (SOC) or SOC treatment alone. The primary objective compared overall survival (OS) between groups. Secondary objectives included safety assessments, progression-free survival (PFS), and tumor responses based on RECIST 1.1 criteria. Exploratory analyses included immunologic assessments and correlates with OS. Results: Between 2013 and 2016, 462 patients were randomized 2:1, 307 to the combination group and 155 to the SOC group. Median OS in the combination group was 27.7 months [95% confidence interval (CI) 23.0–35.9] and 32.4 months (95% CI, 22.5–) in the SOC group HR of 1.10 (95% CI, 0.83–1.40). PFS was 6.0 months and 7.83 months for the combination and SOC groups, respectively [HR = 1.15 (95% CI, 0.92–1.44)]. The ORR was 42.7% (95% CI, 37.1–48.4) for the combination group and 39.4% (95% CI, 31.6–47.5) for the SOC group. Median follow up was 29 months (0.4–47.7 months). On the basis of the lack of clinical efficacy, the ADAPT trial was terminated on February 17, 2017. Immune responses were detected in 70% of patients treated with Rocapuldencel-T, and the magnitude of the immune response positively correlated with OS. In addition, we report the survival-predictive value of measuring IL-12 produced by the DC vaccine and the observation that high baseline numbers of T regulatory cells are associated with improved outcomes in DC-treated patients, but are associated with poor outcomes in patients receiving SOC treatment. No serious adverse events attributed to the study medication have been reported to date. Conclusions: Rocapuldencel-T did not improve OS in patients treated with combination therapy, although the induced immune response correlated with OS. Moreover, we identified two potential survival-predictive biomarkers for patients receiving DC based immunotherapy, IL-12 produced by the DC vaccine and higher numbers of T regulatory cells present in the peripheral blood of patients with advanced RCC.

Approaches to deplete persistent HIV infection are needed. We investigated the combined impact of the latency reversing agent vorinostat (VOR) and AGS-004, an autologous dendritic cell immunotherapeutic, on the HIV reservoir. HIV+, stably treated participants in whom resting CD4+ T cell-associated HIV RNA (rca-RNA) increased after VOR exposure ex vivo and in vivo received 4 doses of AGS-004 every 3 weeks, followed by VOR every 72 hours for 30 days, and then the cycle repeated. Change in VOR-responsive host gene expression, HIV-specific T cell responses, low-level HIV viremia, rca-RNA, and the frequency of resting CD4+ T-cell infection (RCI) was measured at baseline and after each cycle. No serious treatment-related adverse events were observed among five participants. As predicted, VOR-responsive host genes responded uniformly to VOR dosing. Following cycles of AGS-004 and VOR, rca-RNA decreased significantly in only two participants, with a significant decrease in SCA observed in one of these participants. However, unlike other cohorts dosed with AGS-004, no uniform increase in HIV-specific immune responses following vaccination was observed. Finally, no reproducible decline of RCI, defined as a decrease of >50%, was observed. AGS-004 and VOR were safe and well-tolerated, but no substantial impact on RCI was measured. In contrast to previous clinical data, AGS-004 did not induce HIV-specific immune responses greater than those measured at baseline. More efficacious antiviral immune interventions, perhaps paired with more effective latency reversal, must be developed to clear persistent HIV infection.

Pathogenic human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) infection of humans and rhesus macaques (RMs) induces persistently high production of type I interferon (IFN-I), which is thought to contribute to disease progression. To elucidate the specific role of interferon alpha (IFN-α) in SIV pathogenesis, 12 RMs were treated prior to intravenous (i.v.) SIV mac239 infection with a high or a low dose of an antibody (AGS-009) that neutralizes most IFN-α subtypes and were compared with six mock-infused, SIV-infected controls. Plasma viremia was measured postinfection to assess the effect of IFN-α blockade on virus replication, and peripheral blood and lymphoid tissue samples were analyzed by immunophenotypic staining. Consistent with the known antiviral effect of IFN-I, high-dose AGS-009 treatment induced a modest increase in acute-phase viral loads versus controls. Four out of 6 RMs receiving a high dose of AGS-009 also experienced an early decline in CD4 + T cell counts that was associated with progression to AIDS. Interestingly, 50% of the animals treated with AGS-009 (6/12) developed AIDS within 1 year of infection compared with 17% (1/6) of untreated controls. Finally, blockade of IFN-α decreased the levels of activated CD4 + and CD8 + T cells, as well as B cells, as measured by PD-1 and/or Ki67 expression. The lower levels of activated lymphocytes in IFN-α-blockaded animals supports the hypothesis that IFN-α signaling contributes to lymphocyte activation during SIV infection and suggests that this signaling pathway is involved in controlling virus replication during acute infection. The potential anti-inflammatory effect of IFN-α blockade should be explored as a strategy to reduce immune activation in HIV-infected individuals. IMPORTANCE Interferon alpha (IFN-α) is a member of a family of molecules (type I interferons) that prevent or limit virus infections in mammals. However, IFN-α production may contribute to the chronic immune activation that is thought to be the primary cause of immune decline and AIDS in HIV-infected patients. The study presented here attempts to understand the contribution of IFN-α to the natural history and progression of SIV infection of rhesus macaques, the primary nonhuman primate model system for testing hypotheses about HIV infection in humans. Here, we show that blockade of IFN-α action promotes lower chronic immune activation but higher early viral loads, with a trend toward faster disease progression. This study has significant implications for new treatments designed to impact the type I interferon system.

The physiological balance between pro- and anti-inflammatory processes is dysregulated in inflammatory bowel diseases (IBD) as in Crohn's disease and ulcerative colitis. Conventional therapy uses anti-inflammatory and immunosuppressive corticosteroids to treat acute-phase symptoms. However, low remission rate and strong side effects of these therapies are not satisfying. Thus, there is a high medical need for new therapeutic strategies. Soluble CD83, the extracellular domain of the transmembrane CD83 molecule, has been reported to have interesting therapeutic and immunosuppressive properties by suppressing dendritic cell (DC)-mediated T-cell activation and inducing tolerogenic DCs. However, the expression and function of CD83 in IBD is still unknown. Here, we show that CD83 expression is upregulated by different leukocyte populations in a chemical-induced murine colitis model. Furthermore, in this study the potential of sCD83 to modulate colitis using an experimental murine colitis model was investigated. Strikingly, sCD83 ameliorated the clinical disease symptoms, drastically reduced mortality, and strongly decreased inflammatory cytokine expression in mesenteric lymph nodes and colon. The infiltration of macrophages and granulocytes into colonic tissues was vigorously inhibited. Mechanistically, we could show that sCD83-induced expression of indolamine 2,3-dioxygenase is essential for its protective effects.

Modulation of immune responses is one of the main research aims in transplant immunology. In this study, we investigate the local immunomodulatory properties of soluble CD83 (sCD83) at the graft-host interface using the high-risk corneal transplantation model. In this model, which mimics the inflammatory status and the preexisting vascularization of high-risk patients undergoing corneal transplantation, allogeneic donor corneas are transplanted onto sCD83-treated recipient animals. This model allows the direct and precise application of the immune modulator at the transplantation side. Interestingly, sCD83 was able to prolong graft survival after systemic application as well as after topical application, which is therapeutically more relevant. The therapeutic effect was accompanied by an increase in the frequency of regulatory T cells and was mediated by the immune-regulatory enzyme IDO and TGF-β. In vitro, sCD83 induced long-term IDO expression in both conventional and plasmacytoid dendritic cells via autocrine or paracrine production of TGF-β, a cytokine previously shown to be an essential mediator of IDO-dependent, long-term tolerance. These findings open new treatment avenues for local immune modulation after organ and tissue transplantation.

Ribonucleic acid (RNA) is gaining utility as a key component of immunotherapeutics to transiently express antigens or to modulate endogenous gene expression for clinical applications. As a key ancillary component of clinical grade products, RNA requires a robust method for quality control. Here we evaluated the microfluidics based platform and slab electrophoresis for determination of integrity, concentration and size of four in vitro-transcribed RNA products with sizes of 1611, 808, 475 and 290 nucleotides (nts). Our data demonstrate that the Bioanalyzer can determine both size and integrity of the RNA, but the analysis suffers from a strong well position effect. For the RNAs tested, the integrity values obtained by the Bioanalyzer demonstrate a reverse correlation with the size of the molecule and are lower than those obtained using slab electrophoresis. Agarose gel electrophoresis produced the information on size of the RNA molecule with good precision, accuracy and reproducibility. We highlight observations which need to be taken into account when developing and qualifying a method of choice for assessment of in vitro-transcribed RNA using either approach.

Although analytical treatment interruption is used as a strategy to test immunotherapeutic agents in HIV-infection, it may pose a risk for study participants. The potential risks of short-term interruption of antiretroviral therapy (ART) during treatment with an autologous dendritic cell immune-based therapy (AGS-004-001) were assessed using data from a subgroup of subjects in the strategies for management of antiretroviral therapy (SMART) study with matched eligibility criteria. A retrospective subgroup analysis of the SMART study population using the eligibility criteria and treatment stopping rules of AGS-004-001 study was analyzed. Key inclusion criteria for AGS-004-001 study were applied to the data collected from participants of the SMART study. There were 440 of 2,720 on the drug conservation arm and 436 of 2,752 on the viral suppression arm that matched the AGS-004-001 inclusion criteria and were used in the SMART subgroup analysis. In the first 16 weeks following randomization into the SMART study there were no deaths in either subgroup. There were two AIDS-related events in the drug conservation subgroup and one in the viral suppression subgroup, making the overall risk of AIDS-related events 2 per 100 person years (0.005%) and 1 per 100 person years (0.002%) in the two subgroups, respectively. There were 6/440 subjects (1.4%) in the drug conservation subgroup and 4/436 subjects (0.92%) in the viral suppression subgroup who experienced Grade 2 adverse events. These results demonstrated that analytical treatment interruption within the context of highly selective, closely monitored studies assessing the antiviral activity of immune-based agents should be an acceptable strategy for at least 16 weeks.

Background. Tolerogenic dendritic cells (Tol-DCs) play a critical role in inducing and maintaining tolerance. Recognizing that both T-cell inactivation and activation are contingent on signals provided by DCs and that graft-specific activated T cells are major mediators of transplant rejection, we aimed to create an environment favoring Tol-DCs with a novel reagent, human soluble CD83 (hsCD83). Methods. Life-supporting orthotopic kidney transplantation was performed in a C57BL/6-to-BALB/c mouse model. The study group was treated with hsCD83 (100 μg/mouse/day, postoperative days -1 to +7, intravenously) and compared with untreated controls. Results. Treatment with hsCD83 achieved kidney allograft tolerance (> 100 days), with negligible antidonor antibody detected. In contrast, kidney grafts in untreated recipients demonstrated severe rejection after 35 days, characterized by cellular infiltration, interstitial hemorrhage and edema, and glomerular and tubular necrosis, as well as high antidonor antibody titers. In addition, splenic DCs of tolerant recipients exhibited significantly decreased levels of surface major histocompatibility complex class II, CD40, CD80, and intracellular interleukin-12, as well as reduced allogeneic stimulatory capacity. Adoptive transfer of CD11c + DCs from tolerant hsCD83-treated animals induced kidney allograft tolerance in syngeneic recipients. Blocking indoleamine 2,3-dioxygenase with 1-methyl-tryptophan (15 mg/mouse/ day; gavage) prevented the immunosuppressive effect of hsCD83, abrogating hsCD83-induced Tol-DCs and graft tolerance, and leading to acute kidney graft rejection in 22 days. Conclusion. hsCD83 alone was capable of inducing kidney allograft tolerance through a mechanism involving Tol-DC generation and, at least in part, indoleamine 2,3-dioxygenase activity. Because sCD83 is of human origin, the therapeutic approach used in our mouse transplant model holds significant promise for clinical transplantation.

Background. Recombinant human soluble CD83 had previously exhibited significant immunosuppressive properties that involved interference with dendritic cell maturation in both mouse and humans, inhibition of autoimmunity in mice, and induction of antigen-specific mouse cardiac allograft tolerance when used in combination with other immunosuppressive drugs. Our current research focus turned to examining the effects of peritransplant soluble CD83 (sCD83) administration on prevention of chronic renal allograft rejection. Methods. Fisher344-to-Lewis orthotopic rat renal transplants were performed with sequential recipient killing on postoperative days (PODs) 2, 14, and 140 to examine both the acute and chronic effects of peritransplant sCD83 treatment in rat recipients. Results. Recipients treated with sCD83 exhibited a marked decrease in IgM and IgG deposition in the graft and antidonor antibody levels in the circulation, as early as POD14 and persisting until POD140. sCD83 treatment also reduced the infiltration ofT cells and monocytes into the graft tissue and inhibited intragraft expression ofMyD88 and inflammatory cytokine levels during the observation period. sCD83-treated grafts demonstrated normal histology beyond POD140, including dramatic reductions in tubular atrophy and interstitial fibrosis compared with untreated recipients. Conclusion. We have demonstrated that peritransplant treatment with recombinant sCD83 attenuates both innate and adaptive immune responses and leads to prevention of chronic rejection in a rat renal transplant model. Because sCD83 is of human origin, the therapeutic approach used in our rodent transplant model holds significant promise for clinical transplantation.

Background. Dendritic cells (DCs) are crucial regulators of immunity and important in inducing and maintaining tolerance. Here, we investigated the potential of a novel DC-immunomodulating agent, soluble CD83 (sCD83), in inducing transplant tolerance. Methods. We used the C3H-to-C57BL/6 mouse cardiac transplantation model that exhibits a combination of severe cell-mediated rejection and moderate antibody-mediated rejection and investigated whether sCD83 could augment a combination therapy consisting of Rapamycin (Rapa) and anti-CD45RB monoclonal antibody (α-CD45) to prolong allograft survival. Results. Monotherapies consisting of Rapa and α-CD45 were incapable of preventing rejection. However, all treatments involving sCD83 were capable of (1) down-modulating expression of various DC surface molecules, such as major histocompatibility complex class II and costimulatory molecules, (2) reducing the allogeneic stimulatory capacity of the DCs, and (3) significantly inhibiting antidonor antibody responses. Most striking results were observed in the triple therapy-treated group, sCD83+Rapa+α-CD45, where cell-mediated rejection and antibody-mediated rejection were abrogated for over 100 days. Donor-specific tolerance was achieved in long-term surviving recipients, because donor skin transplants were readily accepted for an additional 100 days, whereas third-party skin grafts were rejected. Success of triple therapy treatment was accompanied by enhancement of tolerogenic-DCs that conferred antigen-specific protection on adoptive transfer to recipients of an allogeneic heart graft. Conclusions. Our study revealed that sCD83 is capable of attenuating DC maturation and function, and inducing donor-specific allograft tolerance, in the absence of toxicity. Thus, sCD83 seems to be a safe and valuable counterpart to current DC-modulating agents.

Bone marrow-derived dendritic cells (DCs) are cells of the immune system that have been used as a tool to boost, modulate, or dampen immune responses. In the context of autoimmunity, DCs can be modified to express immunoregulatory products encoded by transgenes, and used therapeutically in adoptive cellular therapy. DCs that were lentivirally transduced (lt) to express interleukin 4 (IL-4) can significantly delay or prevent the onset of autoimmune diabetes in nonobese diabetic (NOD) mice. However, modifying cells using viral vectors carries the dual risk of oncogenicity or immunogenicity. This study demonstrates that NOD DCs, electroporated with "translationally enhanced" IL-4 mRNA (eDC/IL-4), can be equally efficient therapeutically, despite the reduced amount and shorter duration of IL-4 secretion. Moreover, a single injection of eDC/IL-4 in NOD mice shortly after the onset of hyperglycemia was able to maintain stable glycemia for up to several months in a significant fraction of treated mice. Treatment with eDC/IL-4 boosted regulatory T (Tregs) cell functions and modulated T helper responses to reduce pathogenicity. Thus, treatment with DCs, electroporated with modified IL-4 mRNA to express IL-4 for up to 24 hours, constitutes a viable cellular therapy approach for the regulation of autoimmune diabetes, as a preferred alternative to the use of viral vectors.

The formation of aberrant disulfide bonds is a structural consideration for the manufacturing of the extracellular domain of human CD83 (hCD83ext), a potential therapeutic protein. In certain instances, hCD83ext protein products, even when stored frozen, tended to dimerize or even multimerize through the formation of aberrant intermolecular disulfide bonds. Herein, we discovered an analytical inconsistency and applied a modified sample preparation protocol for proper structural analysis of hCD83ext products which are heterologously expressed in Escherichia coli and subsequently purified. In addition, a mutant derivative with the Cys100Ser mutation was identified as an improved version which did not form dimers or multimers. The identification of this mutant variant as a more potent therapeutic protein than other hCD83ext species demonstrated that the structural variation associated with disulfide bond formation can be a critical issue for rigorous control of the quality and bioactivity of therapeutic proteins. The application of this mutant variant for protein therapeutics is currently under exploration.

Antiretroviral therapy represents a major breakthrough for the management of HIV-infected patients; however, it is not without side effects and is a life-long commitment. Thus, the development of novel strategies to enhance immune response and control viral replication are needed in order to limit exposure to antiretroviral therapy. To date, immunotherapies consisting of monocyte-derived dendritic cells expressing HIV antigens have elicited only limited immunogenicity and/or viral control. Thus, taking into consideration the variability of HIV, an investigational immunotherapeutic product (AGS-004, Argos Therapeutics Inc., NC, USA) that consists of autologous dendritic cells co-electroporated with in vitro transcribed RNA encoding four of the patient’s own HIV antigens was developed. Based on the encouraging immunogenicity and tolerance observed in a Phase I study, a Phase II study has been initiated with good tolerance and partial viral control. A second Phase II placebo-controlled study is about to initiate.

4557Background: The Phase 3 ADAPT trial evaluates overall survival (OS) of Rocapuldencel-T (Roca) in combination (combo) with standard-of-care (SoC) for the treatment of newly diagnosed mRCC compar...

31 Background: AGS-003 is an immunotherapy consisting of autologous dendritic cells electroporated with amplified total tumor RNA plus synthetic CD40L RNA and is currently being tested in combination with standard of care to extend survival of newly diagnosed metastatic renal cell carcinoma (RCC) patients in the Phase 3 ADAPT clinical trial. We set out to establish a model system based on the Renca mouse model to more thoroughly study the AGS-003 mechanism of action and identify optimal combination therapies, including with a PD1 checkpoint inhibitor (aPD1 CPI). Methods: Mouse DC precursors were processed in a similar manner to how human monocytes are processed to manufacture AGS-003. Mature DCs were injected s.c. to treat BALB/c mice in an orthotopic syngeneic RCC model. This model system was utilized to test the efficacy and mechanism of action of the AGS-003-like homologous mouse DCs in combination with a murine monoclonal antibody PD1 CPI (anti-mPD1). Results: Murine DCs with similar properties to AGS-003 in combination with anti-mPD1 and sunitinib, resulted in recruitment and migration of lymphocytes into the tumor microenvironment and an increase in peripheral blood CD8+CD28+CD45RA- memory T cells in vivo. Multiple combination dosing strategies were tested and only one dosing regimen (DCs administered prophylactically followed by aPD1 mAb administered therapeutically) showed a substantial synergistic effect (67 days median OS) while all other DC/aPD1 dosing combinations did not exceed the efficacy of DC monotherapy treatment (44.5-48 days median OS). Control animals treated with PBS had a median OS of 29 days. Conclusions: These data demonstrate the importance of the administration sequence for active immunotherapy and aPD1 CPI combination therapy. Our data suggest that the cellular immune response must be initiated and established prior to administration of the aPD1 CPI/sunitinib combination therapy in order to observe synergy in this RCC mouse model. This model may be useful to explore additional combination therapies and effective treatment regimens with other therapeutic agents to guide future clinical development.

Dendritic cell (DC)-based immunotherapeutics must induce robust CTL capable of killing tumor or virally infected cells in vivo. In this study, we show that RNA electroporated post maturation and coelectroporated with CD40L mRNA (post maturation electroporation (PME)-CD40L DC) generate high-avidity CTL in vitro that lyse naturally processed and presented tumor Ag. Unlike cytokine mixture-matured DC which induce predominantly nonproliferative effector memory CD45RA+ CTL, PME-CD40L DC prime a novel subset of Ag-specific CTL that can be expanded to large numbers upon sequential DC stimulation in vitro. We have defined these cells as rapidly expanding high-avidity (REHA) CTL based on: 1) the maintenance of CD28 expression, 2) production of high levels of IFN-γ and IL-2 in response to Ag, and 3) the demonstration of high-avidity TCR that exhibit strong cytolytic activity toward limiting amounts of native Ag. We demonstrate that induction of REHA CTL is dependent at least in part on the production of IL-12. Interestingly, neutralization of IL-12 did not effect cytolytic activity of REHA CTL when Ag is not limiting, but did result in lower TCR avidity of Ag-reactive CTL. These results suggest that PME-CD40L DC are uniquely capable of delivering the complex array of signals needed to generate stable CD28+ REHA CTL, which if generated in vivo may have significant clinical benefit for the treatment of infectious disease and cancer.

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

Identification of antibody targets associated with malignant disease is indispensable to developing passive and active antibody-based therapeutics or diagnostic agents. We have developed a novel technique combining Western blotting, genetic profiling, and mass spectroscopy that allows for the rapid and unambiguous identification of such antigens in a high-throughput manner. Herein, we demonstrate this technique, designated Ab SCAN, by deducing the known target of a monoclonal antibody and by identifying a new antigen that was observed to be the frequent target of humoral immune responses in prostate cancer patients. In both instances, a specific antigen emerged as the sole protein candidate. The newly identified antigen, mannose-6-phosphate/IGF II receptor, may be an important naturally immunogenic antigen involved in prostate cancer. The Ab SCAN technique is uniquely suited to the analysis of longitudinal serum samples from clinical studies and could be a powerful tool to correlate humoral immune responses directed against discreet antigens with clinical events.

The history of tumor biomarker discovery has been one of limited success. Population based screens are few and of limited clinical usefulness. Biomarkers that are able to segregate patients by diagnosis, prognosis and appropriate therapeutic selection are in great need and will be the basis of the clinical management in the future. This review sets out the challenges inherent in the field of tumor biomarker discovery and the tools that we are using to meet that challenge. It is now possible, using this suite of technologies, to discuss novel tumor biomarkers in terms of a pipeline rather than single unique events in research. The future of clinical oncology management will use markers such as those being identified via these techniques to improve patient care through better diagnosis and hopefully to achieve greater success in treatment by exploiting tumor markers as therapeutic targets.

402 Background: AGS-003 is an autologous tumor RNA-loaded dendritic cell-based immunotherapy being tested in advanced renal cell carcinoma (RCC) patients. The immunologic specificity for the patient’s own tumor is achieved using amplified tumor RNA electroporated into monocyte derived dendritic cells. To produce AGS-003 for RCC patients the RNA is amplified from a 100 mg primary tumor sample obtained via nephrectomy. In this non treatment study we evaluated the feasibility of RNA amplification from MIBC tissue acquired by transurethral resection of bladder tumor (TURBT). Methods: MIBC tissue was obtained via TURBT. Following draining of the irrigant used during the TURBT procedure, tissue was placed into an RNA preservative solution to prevent RNA degradation until processing. Methods developed for the amplification of RCC tumor RNA and RNA quality testing were applied to the RNA extracted from the MIBC specimens. Results: This work demonstrated that the methods developed for the amplification and testing of RNA from RCC can be successfully employed for the amplification of RNA from MIBC specimens collected by TURBT. Results demonstrated that the total RNA yields obtained from bladder tissue exceed that of similar masses of primary RCC tumors. This finding enabled the reduction in the amount of starting material from 100 mg to 50 mg of bladder tissue. The amount of amplified RNA produced from the lower bladder cancer masses were sufficient to support the production of immunotherapy at full scale (17 doses average). Conclusions: These data demonstrate the feasibility of RNA extraction and amplification from muscle invasive bladder cancer tissue and supports our planned phase II clinical study. [Table: see text]

Cytomegalovirus (CMV) infection is a serious complication of allogeneic bone marrow transplantation (BMT). CMV disease can usually be prevented by passive immunization with donor-derived CMV-pp65-specific T-cell clones if provided early post-BMT. The classic method of generating CMV-specific T-cell clones requires donor-derived fibroblast lines infected with CMV as stimulators, thus limiting the availability of CMV immunotherapy to those patients for whom a donor skin biopsy can be obtained 6 to 8 weeks pretransplantation. To overcome this limitation we have used monocyte-derived dendritic cells (DCs) to induce donor anti-CMV cytotoxic T lymphocytes (CTLs). Matured, adeno-pp65-infected DCs were added at day 0 and at day 7 of a 2-week culture of donor peripheral blood mononuclear cells. DC-primed cultures were compared with cultures stimulated in an identical fashion with CMV-infected fibroblasts or with adeno-pp65-infected freshly isolated blood monocytes. Specific killing of CMV-infected fibroblasts was detected in all except the culture stimulated with pp65-infected monocytes. DCs infected after maturation elicited greater CTL activity than did DCs matured after infection. A series of 5 CD8+ clones from a fibroblast-stimulated culture and 7 CD8+ clones from a mature-DC-stimulated culture derived from a single HLA-A*0201+ individual were characterized. All 12 clones lysed autologous CMV-infected fibroblasts. All except 1 clone from the CMV-infected fibroblast arm (fibroblast arm) lysed vaccinia-pp65-infected B-lymphoblastoid cell lines (BLCLs); none lysed vaccinia-pp150-infected or noninfected BLCLs. Ten of 10 CD8+ clones tested were restricted by HLA-A*0201. Seven of the 12 clones were Vbeta6+ (2 from the fibroblast arm and 5 from the DC arm) with an identical Vbeta6.1-J1.4 sequence. Three clones from the fibroblast arm and 5 clones from the DC arm recognized the pp65 peptide NLVPMVATV (amino acids [aa], 495-503). These data show that CMV-specific T-cell clones with similar restriction patterns, T cell-receptor usage, and specificity can be generated using monocyte-derived pp65-infected-DC or CMV-infected-fibroblast stimulators. This approach should broaden the applicability of CMV-specific T-cell immunotherapy to a wider spectrum of patients by reducing the time required to generate CMV-specific T-cell clones. (Biol Blood Marrow Transplant 2001;7(5):247-56.) Biol Blood Marrow Transplant 2001;7(5):247-56.

Studies from several laboratories have shown that administration of E1-deleted Ad vectors results only in transient transgene expression in the lungs of immunocompetent animals. This is due, at least in part, to destruction of vector-transduced cells by host cellular immune responses (predominantly CD8(+) CTLs) directed against viral proteins and/or immunogenic transgene products. We have previously demonstrated that E1-deleted Ad vectors can lead to persistent expression of human cystic fibrosis transmembrane conductance regulator (hCFTR) in the lungs of several strains of immunocompetent mice, despite the presence of Ad-specific CTLs. However, we found that these same vectors gave rise only to transient hCFTR expression in the lungs of rhesus monkeys. We have constructed new Ad vectors that coexpress both hCFTR and the ICP47 gene from herpes simplex virus. ICP47 has been shown to inhibit the transporter associated with antigen presentation, thus blocking major histocompatibility antigen I (MHC class I)-mediated antigen presentation to CD8(+) T cells. The Ad/hCFTR/ICP47 vector decreased levels of cell-surface MHC class I molecules on infected monkey and human cell lines. Similar results were obtained with primary human cells and primary monkey airway epithelial cells. In vitro studies showed that the Ad/hCFTR/ICP47 vector decreased cytolysis by both monkey and human CTLs. When Ad/hCFTR/ICP47 was administered to the lungs of rhesus monkeys, it inhibited the generation of Ad-specific CTLs. However, natural killer cell activity was enhanced in monkeys treated with the Ad/hCFTR/ICP47 vector.

Dendritic cells (DCs) transfected with total amplified tumor cell RNA have the potential to induce broad antitumor immune responses. However, analytical methods required for quantitatively assessing the integrity, fidelity, and functionality of the amplified RNA are lacking. We have developed a series of assays including gel electrophoresis, northern blot, capping efficiency, and microarray analysis to determine integrity and fidelity and a model system to assess functionality after transfection into human DCs. We employed these tools to demonstrate that modifications to our previously reported total cellular RNA amplification process including the use of the Fast Start High Fidelity (FSHF) PCR enzyme, T7 Powerswitch primer, post-transcriptional capping and incorporation of a type 1 cap result in amplification of longer transcripts, greater translational competence, and a higher fidelity representation of the starting total RNA population. To study the properties of amplified RNA after transfection into human DCs, we measured protein expression levels of defined antigens coamplified with the starting total RNA populations and measured antigen-specific T cell expansion in autologous DC-T cell co-cultured in vitro. We conclude from these analyses that the improved RNA amplification process results in superior protein expression levels and a greater capacity of the transfected DCs to induce multifunctional antigen-specific memory T cells.Molecular Therapy-Nucleic Acids (2013) 2, e91; doi:10.1038/mtna.2013.18; published online 7 May 2013.

e14532Background: AGS-003 is an immunotherapy consisting of autologous dendritic cells electroporated with amplified total tumor RNA plus synthetic CD40L RNA and is currently being tested in combin...

Electroporation of mature dendritic cells (DC) with RNA-encoding CD40L greatly enhances the production of interleukin (IL)-12, a proinflammatory cytokine necessary for the induction of T-cell immunity. Results presented herein reveal a correlation between the priming of CD28(+) antigen-reactive effector memory cytotoxic T lymphocytes (CTL) displaying 3 or 4 simultaneous effector functions and the quantity of IL-12 produced by postmaturation electroporation-CD40L DC. By using multiparameter flow cytometry, the quantities of IL-12 needed to prime naive antigen-reactive T cells to simultaneously produce interferon-γ and tumor necrosis factor-α in the presence or absence of IL-2 secretion in conjunction with lytic activity defined by CD107a expression can be used to determine the overall potency of a DC product. In the presence of IL-12, CTL differentiation toward lytic function is not accompanied by a reduction in the secretion of interferon-γ and tumor necrosis factor-α. Therefore, by measuring the availability of IL-12 one can predict the potency of a DC immunotherapeutics in relation to its ability to drive distinct effector memory CTL subsets with multifunctional activities.

Immunogenicity, manufacturing feasibility, and safety of a novel, autologous dendritic cell (DC)-based immunotherapy (AGS-004) was evaluated in ten human immunodeficiency virus type 1 (HIV-1)-infected adults successfully treated with antiretroviral therapy (ART). Personalized AGS-004 was produced from autologous monocyte-derived DCs electroporated with RNA encoding CD40L and HIV antigens (Gag, Vpr, Rev, and Nef) derived from each subjects' pre-ART plasma. Patients received monthly injections of AGS-004 in combination with ART. AGS-004 was produced within a mean of 6 weeks and yielded 4-12 doses/subject Full or partial HIV-specific proliferative immune responses occurred in 7 of 9 evaluable subjects. Responses were specific for the AGS-004 presented HIV antigens and preferentially targeted CD8(+) T cells. Mild adverse events included flu-like symptoms, fatigue, and injection site reactions. No evidence of autoimmunity, changes in viral load, or significant changes in absolute CD4(+) and CD8(+) T cell counts were observed. This pilot study supports the further clinical investigation of AGS-004.

Dendritic cells (DC) for the immunotherapy of cancer and infectious disease require the appropriate maturation and activation signals to effectively present antigen to drive a proinflammatory response. Here we present a comparison of 4 different maturation protocols for antigen-encoded mRNA electroporated DC. Two protocols rely on cytokine-induced maturation given either preelectroporation or postelectroporation. In addition to the cytokine treatment, 2 further maturation protocols use coelectroporation of CD40L mRNA, with antigen-encoding RNA, to deliver CD40 signals. There were no significant differences in expression of costimulatory molecules such as CD80, CD83, and CD86 or the levels of expression of major histocompatibility complexes. However, results indicate that delivery of an inflammatory signal that includes interferon-gamma before the CD40 signal results in high levels of expression of interleukin-12 that was not seen in the absence of CD40L mRNA. All 4 preparations could induce expansion of primary MART-1-specific CD8+ T cells from healthy donors in vitro, but only the 2 processes receiving CD40L could induce interferon-gamma expression by those responder cells. Only DC electroporated with CD40L RNA after delivery of the inflammatory signal (PME-CD40L DC), could drive the long-term expansion of MART-1-reactive cells that displayed a CD28+/CD45RA- effector/memory phenotype with strong cytolytic activity.

Self tolerance to MHC class I-restricted nonmutated self Ags is a significant hurdle to effective cancer immunotherapy. Compelling evidence is emerging that altered peptide ligands can be far more immunogenic than their corresponding native epitopes; however, there is no way to reliably predict which modifications will lead to enhanced native epitope-specific immune responses. We reasoned that this limitation could be overcome by devising an empirical screen in which the nearly complete combinatorial spectrum of peptides of optimal length can be rapidly assayed for reactivity with a MHC class I-restricted cytotoxic T cell clone. This method, solid-phase epitope recovery, quantitatively ranks all reactive peptides in the library and allows selection of altered peptide ligands having desirable immunogenic properties of interest. In contrast to rationally designed MHC anchor-modified peptides, peptides identified by the present method are highly substituted in predicted TCR contact residues and can reliably activate and expand effector cell populations in vitro which lyse target cells presenting the wild-type epitope. We demonstrate that solid-phase epitope recovery peptides corresponding to a poorly immunogenic epitope of the melanoma Ag, gp100, can reliably induce wild-type peptide-specific CTL using normal donor T cells in vitro. Furthermore, these peptides can complement one another to induce these responses in an overwhelming majority of normal individuals in vitro. These data provide a rationale for the design of superior vaccines comprising a mixture of structurally diverse yet functionally convergent peptides.

4524^ Background: Treatment for metastatic renal cell carcinoma (mRCC) has evolved significantly over the last decade due to enhanced understanding of the biology of RCC resulting in availability o...

Replication-deficient recombinant adenovirus (Ad) encoding human gp100 or MART-1 melanoma Ag was used to transduce human dendritic cells (DC) ex vivo as a model system for cancer vaccine therapy. A second generation E1/E4 region deleted Ad which harbors the CMV immediate-early promoter/enhancer and a unique E4-ORF6/pIX chimeric gene was employed as the backbone vector. We demonstrate that human monocyte-derived DC are permissive to Ad infection at multiplicity of infection between 100 and 500 and occurs independent of the coxsackie Ad receptor. Fluorescent-labeled Ad was used to assess the kinetics and distribution of viral vector within DC. Ad-transduced DC show peak transgene expression at 24–48 h and expression remains detectable for at least 7 days. DC transduced with replication-deficient Ad do not exhibit any unusual phenotypic characteristics or cytopathic effects. DC transduced with Ad2/gp100v2 can elicit tumor-specific CTL in vitro from patients bearing gp100+ metastatic melanoma. Using a panel of gp100-derived synthetic peptides, we show that Ad2/gp100v2-transduced DC elicit Ag-specific CTL that recognize only the G209 and G280 epitopes, both of which display relatively short half-lives (∼7–8 h) on the surface of HLA-A*0201+ cells. Thus, patients with metastatic melanoma are not tolerant to gp100 Ag based on the detection of CD8+ T cells specific for multiple HLA-A*0201-restricted, gp100-derived epitopes.

Background Unabated Type I interferon expression is implicated in the pathogenesis of systemic lupus erythematosus (SLE). A monoclonal anti-IFN-α antibody, AGS-009, which neutralizes a broad range of IFN-α subtypes was developed and humanized for use as a therapeutic treatment for SLE. This is the first human clinical trial using this antibody. Objectives To evaluate safety, pharmacokinetics (PK) and IFN-α neutralizing capacity of a single intravenous (i.v) infusion of AGS-009 in adults with mild to moderate SLE. IFN-a neutralization was assessed by monitoring IFN-α-inducible gene transcription levels. Methods We conducted a phase Ia multicenter, randomized, double blind, placebo-controlled single dose escalation study. Subjects included in the study had mild to moderate SLE based on their disease activity index and clinical laboratory test results but were not screened for elevated IFN-a activity at baseline. Subjects were randomized in 3:1 ratio within each cohort to receive a single i.v. infusion of AGS-009 at 0.01, 0.1, 0.6, 3, 10 and 30 mg/kg or placebo. There were 25 subjects in total (4 subjects per dose level with one replacement subject) and all subjects received AGS-009 or placebo in combination with standard of care. Subjects were monitored for safety based on adverse events (AEs), physical exam and clinical laboratory tests. Serum samples were collected longitudinally before and after drug administration for a period of 85 days to evaluate pharmacokinetics (PK) using a validated ELISA assay. Longitudinal whole blood samples were collected before and after treatment as well and changes in expression levels of 27 IFN-α-inducible genes (IFN-α signature) were evaluated by RT-PCR in five cohorts ≥0.1 mg/kg dose level. Results AGS-009 was safe and well tolerated at each dose level with no AGS-009-related SAEs or dose-limiting toxicities observed. Pharmacokinetic analysis showed that peak serum concentration of AGS-009 increased proportionally to the dose administered ranging from 1.59×102-6.82×105 ng/mL. Mean terminal half-life ranged from 270 to 489 hours across the dosing groups and was consistent with prior results obtained in non-human primates. Prior to AGS-009 treatment, the IFN-α-inducible gene signature was elevated in 17 of 21 subjects evaluated, compared to an average across 8 healthy individuals. At AGS-009 dose levels above 0.6 mg/kg, subjects with elevated baseline IFN-a signatures demonstrated marked decreases in median expression levels which was not observed in placebo subjects. The degree of reduction in post-treatment IFN-α gene expression suggests a trend with the dose level administered. IFN-a signatures in the 4 subjects without elevated levels at baseline were not modulated. Conclusions AGS-009 was shown to be safe and well tolerated at all dose levels. Peak blood levels of AGS-009 following a single i.v. dose were proportional to the doses administered and the half-life remained relatively constant at 11-20 days across the dose groups. AGS-009 treatment at doses >0.6 mg/kg resulted in significant neutralization of IFN-a signatures, consistent with the proposed mechanism of action. Cumulative data from this study warrants continuation of clinical development of AGS-009 and establishing inclusion criteria based on elevated baseline IFN-a levels. Disclosure of Interest I. Tcherepanova Employee of: Argos Therapeutics, M. Curtis Employee of: Argos Therapeutics, M. Sale Consultant for: Argos Therapeutics, F. Miesowicz Shareholder of: Argos Therapeutics, Employee of: Argos Therapeutics, C. Nicolette Shareholder of: Argos Therapeutics, Employee of: Argos Therapeutics

357 Background: During the past decade, VEGF targeted therapies have become standard treatment for advanced RCC. While targeted therapies have yielded improved efficacy, durable remissions are rare, particularly in unfavorable risk subjects. In a pivotal trial, treatment with sunitinib yielded a median OS of 5.3 months for poor risk and 20.7 months for intermediate risk subjects. Similarly, the validation dataset for the Heng risk model (ASCO 2011) revealed a median OS of 8 months for poor risk and 21 months for intermediate risk patients treated with VEGF targeted therapies. Durable responses have been elicited by immunotherapy in RCC. We report an update on patients with mRCC treated with combined VEGF TKI (sunitinib) plus autologous immunotherapy (AGS-003). Methods: In this phase II study, subjects with unfavorable prognosis mRCC (poor and intermediate risk) were treated with sunitinib plus autologous dendritic cell immunotherapy (AGS-003). Treatment consisted of standard 6-week cycles of sunitinib plus AGS-003 (once every 3 weeks x5 doses, then every 12 weeks until PD). Tumor response was assessed per RECIST and subjects were followed for PFS and OS. Immune monitoring samples were taken at screening, baseline and after the third and fifth doses of AGS-003 and analyzed by multiparametric flow cytometry. Results: 21 subjects were treated. As previously reported, the median overall PFS was 11.2 months and the final median OS was 30.2 months. When analyzed by baseline Heng risk status, the median PFS was 19.4 months for intermediate (n=11) and 5.8 months for subjects with poor risk features (n=10) at baseline. The median OS is 39.5+ months for intermediate and 9.1 months for subjects with poor risk. Conclusions: The results from this single-arm phase II study represent a near doubling of expected PFS and OS for unfavorable risk subjects treated with AGS-003 plus sunitinib. Updated survival and immunologic findings will be presented, as 8 of 21 subjects are still alive and continue to be followed. These results support the ongoing phase III ADAPT study, which is designed to validate these encouraging clinical and immunologic findings. Clinical trial information: NCT00678119.

80 Background: AGS-003 is an autologous dendritic cell (DC) immunotherapy prepared from matured monocyte-derived DC co-electroporated with the subject’s own amplified tumor RNA and synthetic CD40L RNA. The mechanism of action (MOA) of AGS-003 was evaluated in combination with sunitinib for treatment of advanced renal cell carcinoma (RCC) in AGS-003-006, an open label phase II trial including subjects with newly diagnosed, unfavorable-risk, metastatic clear cell RCC. The goal of the immune monitoring platform is to identify unique cytotoxic T-cell (CTL) signatures that correlate with clinical outcome in subjects receiving AGS-003 in combination with sunitinib. Methods: Multiparametric flow cytometry was used to identify tumor-reactive CTL subsets induced by AGS-003 based on combinatorial expression patterns of surface markers CD28, CD45RA, CD27 and CCR7. Moreover, further partitioning of each CTL subset identified combinatorial expression patterns of Markers of Immune Function (MIFs) defined as cytokines (IFN-γ TNF-α, IL-2), cytolytic markers (Granzyme b, CD107) and proliferation. Correlates of CTL signatures with clinical outcome were analyzed using an adaptation of a binary tree-structured vector quantization (BTSVQ) approach, originally developed to cluster and visualize large microarray data sets. The BTSVQ approach implements a two-way unsupervised clustering that allows a subject’s CTL signature to be mapped based on both surface marker and MIFs expression patterns to identify unique clustering patterns linked to clinical outcome. Results: Data analysis identified a unique CTL signature (CD28+/CCR7+/CD45RA- phenotype) displaying a broad MIFs profile as a statistically significant correlate to PFS and OS in patients treated with AGS-003. Conclusions: These results support the intended MOA of AGS-003 in vivo, as the induction of anti-tumor central and effector memory CTL responses. These data warrant further immunological evaluation of AGS-003 in the randomized phase III ADAPT study using AGS-003 in combination with standard treatment in RCC subjects.

2532 Background: Dendritic cells (DC) are a powerful tool for stimulating cell-mediated immunity through the effects of CD4+ and CD8+ T cells. This phase II study investigated AGS-003, an autologou...

4588 Background: AGS-003 is an autologous immunotherapy prepared from matured monocyte-derived dendritic cells co-electroporated with the subject's own amplified tumor and synthetic CD40L RNA. Base...

e13006 Background: AGS-003 is an autologous immunotherapy prepared from matured monocyte-derived dendritic cells (DCs) co- electroporated with the subject's own amplified total tumor and synthetic ...