Oncolytic Virotherapy Promotes Intratumoral T Cell Infiltration and Improves Anti-PD-1 Immunotherapy.

Here we report a phase 1b clinical trial testing the impact of oncolytic virotherapy with talimogene laherparepvec on cytotoxic T cell infiltration and therapeutic efficacy of the anti-PD-1 antibody pembrolizumab. Twenty-one patients with advanced melanoma were treated with talimogene laherparepvec followed by combination therapy with pembrolizumab. Therapy was generally well tolerated, with fatigue, fevers, and chills as the most common adverse events. No dose-limiting toxicities occurred. Confirmed objective response rate was 62%, with a complete response rate of 33% per immune-related response criteria. Patients who responded to combination therapy had increased CD8+ T cells, elevated PD-L1 protein expression, as well as IFN-γ gene expression on several cell subsets in tumors after talimogene laherparepvec treatment. Response to combination therapy did not appear to be associated with baseline CD8+ T cell infiltration or baseline IFN-γ signature. These findings suggest that oncolytic virotherapy may improve the efficacy of anti-PD-1 therapy by changing the tumor microenvironment. VIDEO ABSTRACT.

Effects of an anti-TSLP antibody on allergen-induced asthmatic responses.

BACKGROUND: Thymic stromal lymphopoietin (TSLP) is an epithelial-cell-derived cytokine that may be important in initiating allergic inflammation. AMG 157 is a human anti-TSLP monoclonal immunoglobulin G2λ that binds human TSLP and prevents receptor interaction. METHODS: In this double-blind, placebo-controlled study, we randomly assigned 31 patients with mild allergic asthma to receive three monthly doses of AMG 157 (700 mg) or placebo intravenously. We conducted allergen challenges on days 42 and 84 to evaluate the effect of AMG 157 in reducing the maximum percentage decrease in the forced expiratory volume in 1 second (FEV1). We also measured the fraction of nitric oxide in exhaled air, blood and sputum eosinophils, and airway hyperresponsiveness. The primary end point was the late asthmatic response, as measured 3 to 7 hours after the allergen challenge. RESULTS: AMG 157 attenuated most measures of allergen-induced early and late asthmatic responses. The maximum percentage decrease in the FEV1 during the late response was 34.0% smaller in the AMG-157 group than in the placebo group on day 42 (P=0.09) and 45.9% smaller on day 84 (P=0.02). In addition, patients receiving AMG 157 had significant decreases in levels of blood and sputum eosinophils before and after the allergen challenge and in the fraction of exhaled nitric oxide. There were 15 adverse events in the AMG-157 group, as compared with 12 in the placebo group; there were no serious adverse events. CONCLUSIONS: Treatment with AMG 157 reduced allergen-induced bronchoconstriction and indexes of airway inflammation before and after allergen challenge. These findings are consistent with a key role for TSLP in allergen-induced airway responses and persistent airway inflammation in patients with allergic asthma. Whether anti-TSLP therapeutics will have clinical value cannot be determined from these data. (Funded by Amgen; ClinicalTrials.gov number, NCT01405963.).

Homeostasis of human NK cells is not IL-15 dependent.

IL-15 is a proinflammatory cytokine that plays an important role in the development and activation of NK cells and is a potential target for inflammatory disease therapy. Studies conducted in IL-15- and IL-15R knockout mice identified IL-15 as an important cytokine for NK cell homeostasis. Consistent with this information derived from genetically modified mice, we demonstrated that neutralizing IL-15 with a mouse anti-mouse IL-15 mAb (M96) depletes C57BL/6 mouse NK cells. An mAb directed against macaque IL-15 (Hu714MuXHu) was manufactured and demonstrated to block IL-15-induced activation of nonhuman primate (NHP) NK cells in vitro. Neutralization of macaque IL-15 by parenteral administration of Hu714MuXHu reduces (>95%) circulating NK cell counts in NHPs. A blocking mAb directed against human IL-15 (huIL-15; AMG 714) was manufactured. Unexpectedly, when human subjects were treated with the blocking anti-IL-15 Ab AMG 714 in clinical trials, no reductions in circulating NK cell counts were observed despite achieving significantly higher exposures than the levels of Hu714MuXHu needed to cause NK cell count reductions in NHPs in vivo. Both AMG 714 and Hu714MuXHu are able to block huIL-15 activity in a human T cell blast proliferation and IFN-γ production assay. Both Abs block huIL-15-mediated Stat5 activation and CD69 expression in human NK cells. Collectively, these results demonstrate that NK cell homeostasis is obligatorily dependent upon IL-15 in both mice and NHPs, but that IL-15 is dispensable for maintenance of circulating human NK cells.

Inhibition of activation-induced death of dendritic cells and enhancement of vaccine efficacy via blockade of MINOR.

Activation of dendritic cells (DCs) leads to cell maturation, which is accompanied by a regulated pattern of gene expression changes. Two significant and contradictory consequences of DC activation are that, although activation is necessary for maximal T-cell stimulation, it also leads to the initiation of gene expression that results ultimately in cell death. We have identified a gene, MINOR (mitogen-inducible nuclear orphan receptor), that becomes highly up-regulated on activation and whose expression leads to apoptosis in mature DCs. MINOR is a member of the Nur77 family of nuclear orphan receptors, which includes Nur77 and Nurr1. Although Nur77 and Nurr1 are expressed in macrophages and DCs, their expression levels do not change on DC activation. We thus tested the hypothesis that induction of MINOR would lead to an activation-induced cell death in DCs and that its inhibition would increase the lifespan of DCs and improve their vaccine efficacy. To block natural expression of MINOR by DCs, we generated a lentiviral vector that expresses a small interfering RNA. Our results indicate that blockade of MINOR expression dramatically decreases apoptosis in DCs and suggest that this approach may be a novel means to improve the potency of ex vivo-generated DC vaccines.

Talimogene laherparepvec upregulates immune-cell populations in non-injected lesions: findings from a phase II, multicenter, open-label study in patients with stage IIIB-IVM1c melanoma.

BACKGROUND: Talimogene laherparepvec (T-VEC), an oncolytic virus, was designed to selectively replicate in and lyse tumor cells, releasing tumor-derived antigen to stimulate a tumor-specific immune response. METHODS: In this phase II study in patients with unresectable stage IIIB-IV melanoma, we evaluated non-injected lesions to establish whether baseline or change in intratumoral CD8+ T-cell density (determined using immunohistochemistry) correlated with T-VEC clinical response. RESULTS: Of 112 enrolled patients, 111 received ≥1 dose of T-VEC. After a median follow-up of 108.0 weeks, objective/complete response rates were 28%/14% in the overall population and 32%/18% in patients with stage IIIB-IVM1a disease. No unexpected toxicity occurred. Baseline and week 6 change from baseline CD8+ T-cell density results were available for 91 and 65 patients, respectively. Neither baseline nor change in CD8+ T-cell density correlated with objective response rate, changes in tumor burden, duration of response or durable response rate. However, a 2.4-fold median increase in CD8+ T-cell density in non-injected lesions from baseline to week 6 was observed. In exploratory analyses, multiparameter immunofluorescence showed that after treatment there was an increase in the proportion of infiltrating CD8+ T-cells expressing granzyme B and checkpoint markers (programmed death-1, programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte antigen-4) in non-injected lesions, together with an increase in helper T-cells. Consistent with T-cell infiltrate, we observed an increase in the adaptive resistance marker PD-L1 in non-injected lesions. CONCLUSIONS: This study indicates that T-VEC induces systemic immune activity and alters the tumor microenvironment in a way that will likely enhance the effects of other immunotherapy agents in combination therapy. TRIAL REGISTRATION NUMBER: NCT02366195.

NK1.1+ cells mediate the antitumor effects of a dual Toll-like receptor 7/8 agonist in the disseminated B16-F10 melanoma model.

Innate immune stimulation with Toll-like receptor (TLR) agonists is a proposed modality for immunotherapy of melanoma. Here, a TLR7/8 agonist, 3M-011, was used effectively as a single systemic agent against disseminated mouse B16-F10 melanoma. The investigation of the mechanism of antitumor action revealed that the agonist had no direct cytotoxic effects on tumor cells tested in vitro. In addition, 3M-011 retained its effectiveness in scid/B6 mice and scid/NOD mice, eliminating the requirement for T and B cells, but lost its activity in beige (bg/bg) and NK1.1-immunodepleted mice, suggesting a critical role for natural killer (NK) cells in the antitumor response. NK cytotoxicity was enhanced in vivo by the TLR7/8 agonist; this activation was long lasting, as determined by sustained expression of the activation marker CD69. Also, in human in vitro studies, 3M-011 potentiated NK cytotoxicity. TLR7/8-mediated NK-dependent antitumor activity was retained in IFN-alpha/beta receptor-deficient as well as perforin-deficient mice, while depletion of IFN-gamma significantly decreased the ability of 3M-011 to delay tumor growth. Thus, IFN-gamma-dependent functions of NK cell populations appear essential for cancer immunotherapy with TLR7/8 agonists.

First in human phase I trial of 852A, a novel systemic toll-like receptor 7 agonist, to activate innate immune responses in patients with advanced cancer.

PURPOSE: Recent advances in the understanding of innate immunity suggest that an orchestrated sequence of events is required to elicit a productive immune response against cancer. We studied the systemic administration of the Toll-like receptor 7 agonist 852A, a small-molecule imidazoquinoline, in patients with advanced cancer. Preclinical studies showed that 852A stimulates plasmacytoid dendritic cells to produce multiple cytokines, such as IFN-alpha, interleukin-1 receptor antagonist, and IFN-inducible protein-10. Our goal was to define the tolerated dose, pharmacokinetics, pharmacodynamics, and immunologic effects of 852A in humans. EXPERIMENTAL DESIGN: Eligible adult patients with refractory solid organ tumors received i.v. 852A thrice weekly for 2 weeks. Patients who had responses or stable disease were eligible for additional cycles. RESULTS: Twenty-five patients (median age, 55.0 years; 72% male) were enrolled in six cohorts at dose levels of 0.15 to 2.0 mg/m(2). Serum drug levels showed dose proportionality and no evidence of drug accumulation. The maximum tolerated dose was 1.2 mg/m(2); higher doses were limited by fatigue and constitutional symptoms. Increases in IFN-alpha, interleukin-1 receptor antagonist, and IFN-inducible protein-10, immunologic activity, and clinical symptoms were observed in all patients receiving dose levels > or =0.6 mg/m(2). Significant correlations were found between pharmacodynamic biomarkers and pharmacokinetic variables, and an objective clinical response was seen. CONCLUSIONS: 852A was safely administered i.v. at doses up to 1.2 mg/m(2) thrice weekly for 2 weeks with transient or reversible adverse effects. This novel Toll-like receptor 7 agonist is biologically active and holds promise for stimulating innate immune responses. Future trials are warranted to assess its therapeutic role in patients with cancer.

Talimogene Laherparepvec in Combination With Ipilimumab in Previously Untreated, Unresectable Stage IIIB-IV Melanoma.

PURPOSE: Combining immunotherapeutic agents with different mechanisms of action may enhance efficacy. We describe the safety and efficacy of talimogene laherparepvec (T-VEC; an oncolytic virus) in combination with ipilimumab (a cytotoxic T-lymphocyte-associated antigen 4 checkpoint inhibitor) in patients with advanced melanoma. METHODS: In this open-label, multicenter, phase Ib trial of T-VEC in combination with ipilimumab, T-VEC was administered intratumorally in week 1 (10(6) plaque-forming units/mL), then in week 4 and every 2 weeks thereafter (10(8) plaque-forming units/mL). Ipilimumab (3 mg/kg) was administered intravenously every 3 weeks for four infusions, beginning in week 6. The primary end point was incidence of dose-limiting toxicities. Secondary end points were objective response rate by immune-related response criteria and safety. RESULTS: Median duration of treatment with T-VEC was 13.3 weeks (range, 2.0 to 95.4 weeks). Median follow-up time for survival analysis was 20.0 months (1.0 to 25.4 months). Nineteen patients were included in the safety analysis. No dose-limiting toxicities occurred, and no new safety signals were detected. Grade 3/4 treatment-related adverse events (AEs) were seen in 26.3% of patients; 15.8% had AEs attributed to T-VEC, and 21.1% had AEs attributed to ipilimumab. The objective response rate was 50%, and 44% of patients had a durable response lasting ≥ 6 months. Eighteen-month progression-free survival was 50%; 18-month overall survival was 67%. CONCLUSION: T-VEC with ipilimumab had a tolerable safety profile, and the combination appeared to have greater efficacy than either T-VEC or ipilimumab monotherapy.

A set of genes selectively expressed in murine dendritic cells: utility of related cis-acting sequences for lentiviral gene transfer.

Professional antigen presenting cells such as dendritic cells (DC) and macrophages (Mphi) share similar characteristics; however, they differ in their ability to initiate an immune response. DCs are much more potent in priming and stimulating nai;ve T-cells. Thus, DCs are good targets for the expression of foreign genes to elicit and specifically modify immune responses. To identify DC markers cDNA subtraction was performed using murine MHC class II(high), B7(high) bone marrow derived DCs as tester and interferon-gamma/E. coli lipopolysaccaride (LPS) treated bone marrow derived macrophages as driver. Analysis of 114 resulting clones revealed a diverse pattern of DC selective (DC(DeltaMphi)) gene expression including known genes whose expression in DCs had not been previously demonstrated as well as multiple novel genes. For several identified DC(DeltaMphi) genes, proximal promoter elements were isolated and incorporated into self-inactivating lentiviral GFP reporter vectors. Promoter activity was measured in bone marrow derived macrophages or dendritic cells. Of the promoters analyzed those for B7-DC and CCL17 drove strong GFP expression in DCs but not in resting or activated macrophages. The CCL17 promoter offered the highest level of expression in DCs and was further activated by culture with LPS or interleukin-4 (IL-4). In contrast, the B7-DC promoter was induced by IL-4 but not by LPS. Endogenous CCL17 and B7-DC mRNAs were increased similarly in IL-4 cultured DCs but only CCL17 was induced by LPS. Additionally, IL-4 increased cell surface expression of B7-DC in both immature and mature DCs.

Phase I, pharmacokinetic, and pharmacodynamic study of AMG 479, a fully human monoclonal antibody to insulin-like growth factor receptor 1.

PURPOSE: To determine the maximum-tolerated dose (MTD) and to assess the safety, pharmacokinetics, and evidence of antitumor activity of AMG 479, a fully human monoclonal antibody to insulin-like growth factor receptor 1 (IGF-1R). PATIENTS AND METHODS: Patients with advanced solid malignancies or non-Hodgkin's lymphoma received escalating doses of AMG 479 intravenously (IV) every 2 weeks (Q2W). Blood samples were assayed to determine pharmacokinetic parameters and IGF-1R occupancy on neutrophils; fluorodeoxyglucose-positron emission tomography scans were used to assess tumor metabolic effects. RESULTS: Fifty-three patients received 312 infusions of AMG 479 Q2W. Overall, the most common grades 1 to 2 toxicities were fatigue, thrombocytopenia, fever, rash, chills, and anorexia. One dose-limiting toxicity (ie, grade 3 thrombocytopenia) occurred in a patient at 20 mg/kg during course 1; grade 3 thrombocytopenia (n = 8) and grade 3 transaminitis elevations (n = 1) also were reported but not in the escalation phase. The maximum-planned dose of 20 mg/kg was safely administered; thus, an MTD was not reached. High levels of neutrophil IGF-1R binding and increases from baseline in serum IGF-1 levels were observed in the 12- and 20-mg/kg cohorts. Tumor responses included one durable complete response (CR) and one unconfirmed partial response (PR) in two patients with Ewing/primitive neuroectodermal tumors and included one PR and one minor response in two patients with neuroendocrine tumors. The patients with Ewing/PNET who had a CR have remained disease free on therapy after 28 months. CONCLUSION: AMG 479 can be administered safely at 20 mg/kg IV Q2W. The absence of severe toxicities, attainment of serum concentrations associated with high levels of IGF-1R binding on neutrophils, and provocative antitumor activity warrant additional studies of this agent.

Distinct indirect pathways govern human NK-cell activation by TLR-7 and TLR-8 agonists.

NK cells limit the emergence of cancers and viral infections by surveillance of 'missing-self' and 'induced-self' ligands, and by direct recognition of pathogen-associated molecules. We examined individual roles for Toll-like receptors (TLRs)-7 and -8 in human NK-cell activation using synthetic, small molecule agonists of either TLR-7 (imiquimod and 3M-001), TLR-8 (3M-002) or both TLR-7/8 (3M-003 and R-848) for comparison with known ligands of TLR-2 to -9. Tracking cytokine production in PBMC initially revealed that a subset of TLR agonists including polyinosinic-polycytidylic acid (poly I:C), 3M-002, 3M-003, R-848 and single-stranded RNA trigger relatively high levels of IFN-gamma expression by NK cells. Isolated NK cells did not express TLR-7 or TLR-8. Unlike MALP-2 and poly I:C, 3M-001-3 did not induce expression of either CD69 or IFN-gamma by purified NK cells suggesting indirect activation. IL-18 and IL-12p70 were primarily required for induction of IFN-gamma by both synthetic and natural TLR-8 ligands, while type I IFN was required for induction of CD69 on NK cells by the TLR-7 agonist 3M-001. In addition to expression of IFN-gamma and CD69, relative induction of NK-cell cytotoxicity by TLR-7 and TLR-8 agonists was compared. Immune response modifiers (IRMs) with a TLR-8 agonist component (3M-002 and 3M-003) stimulated greater levels of K562 cytolysis than achieved with 3M-001 or IL-2 (1000 units ml(-1)). In vivo NK-cell cytotoxicity was also enhanced by R-848, but not in type I IFNR-deficient mice. We conclude that IRMs can modulate NK-cell function both in vitro and in vivo and that distinct indirect pathways control human NK-cell activation by TLR-7 and TLR-8 agonists.

Synthetic TLR agonists reveal functional differences between human TLR7 and TLR8.

Although TLR7 and TLR8 are phylogenetically and structurally related, their relative functions are largely unknown. The role of TLR7 has been established using TLR7-deficient mice and small molecule TLR7 agonists. The absence of TLR8-selective agonists has hampered our understanding of the role of TLR8. In this study TLR agonists selective for TLR7 or TLR8 were used to determine the repertoire of human innate immune cells that are activated through these TLRs. We found that TLR7 agonists directly activated purified plasmacytoid dendritic cells and, to a lesser extent, monocytes. Conversely, TLR8 agonists directly activated purified myeloid dendritic cells, monocytes, and monocyte-derived dendritic cells (GM-CSF/IL-4/TGF-beta). Accordingly, TLR7-selective agonists were more effective than TLR8-selective agonists at inducing IFN-alpha- and IFN-regulated chemokines such as IFN-inducible protein and IFN-inducible T cell alpha chemoattractant from human PBMC. In contrast, TLR8 agonists were more effective than TLR7 agonists at inducing proinflammatory cytokines and chemokines, such as TNF-alpha, IL-12, and MIP-1alpha. Thus, this study demonstrated that TLR7 and TLR8 agonists differ in their target cell selectivity and cytokine induction profile.

Transduction of donor hematopoietic stem-progenitor cells with Fas ligand enhanced short-term engraftment in a murine model of allogeneic bone marrow transplantation.

Fas-mediated apoptosis is a major physiologic mechanism by which activated T cells are eliminated after antigen-stimulated clonal expansion generates a specific cellular immune response. Because activated T cells are the major effectors of allograft rejection, we hypothesized that genetically modifying allogeneic bone marrow (BM) cells prior to transplantation could provide some protection from host T-cell attack, thus enhancing donor cell engraftment in bone marrow transplantation (BMT). We undertook studies to determine the outcome of lentiviral vector-mediated transduction of Fas ligand (FasL) into lineage antigen-negative (lin(-)) mouse BM cells (lin(-) BMs), in an allogeneic BMT model. FasL-modified lin(-) BMs killed Fas-expressing T cells in vitro. Mice that received transplants of allogeneic FasL(+) lin(-) BMs had enhanced short-term engraftment, after nonmyeloablative conditioning, as compared to controls. We observed no major hepatic toxicity or hematopoietic or immune impairment in recipient mice at these time points. These results suggest potential therapeutic approaches by manipulating lymphohematopoietic stem-progenitor cells to express FasL or other immune-modulating genes in the context of BMT.

Cutting edge: Expression of functional CD137 receptor by dendritic cells.

Interaction between dendritic cells (DCs) and T cells is a prerequisite for the initiation of a T cell response. The molecular nature of this interaction remains to be fully characterized. We report in this work that freshly isolated mouse splenic DCs and bone marrow-derived DCs express CD137 on the cell surface and in soluble form. Triggering CD137 increased the secretion of IL-6 and IL-12 from DCs. More importantly, infusion of an agonistic mAb to CD137 into naive mice enhanced the ability of DCs to stimulate T cell proliferation in response to both alloantigens and a nominal Ag in vitro. This enhancement of DC function is not mediated through activation of T cells, because the effect was also observed in RAG-1 knockout mice that lack T cells. Our findings implicate CD137 as an important receptor involved in the modulation of DC function.