First-in-human trial of rhIL-15 and haploidentical natural killer cell therapy for advanced acute myeloid leukemia.

In vivo expansion of haploidentical natural killer (NK) cell infusions with interleukin-2 (IL-2) can induce remission of refractory acute myeloid leukemia, but efficacy may be hampered by concurrent stimulation of host regulatory T cells. To overcome this limitation, we substituted the NK homeostatic factor IL-15 in 2 phase 1/2 trials. Forty-two patients received either intravenous (IV) (NCT01385423) or subcutaneous (SC) (NCT02395822) recombinant human IL-15 (rhIL-15) after lymphodepleting chemotherapy and haploidentical NK cells. Escalating doses of rhIL-15 (0.3-1.0 µg/kg) were given on 12 consecutive days in a phase 1 trial. Of 26 patients, 36% had robust in vivo NK-cell expansion at day 14, and 32% achieved complete remission. Hypothesizing that SC dosing of rhIL-15 would be safer and better tolerated, 16 patients received 10 once per day doses of SC rhIL-15 at 2.0 µg/kg on a phase 2 trial. NK-cell expansion at day 14 was seen in 27% of the patients, and 40% achieved remission. rhIL-15 induced better rates of in vivo NK-cell expansion and remission compared with previous trials with IL-2, but it was associated with previously unreported cytokine release syndrome (CRS) after SC but not IV dosing. CRS was observed in 56% of patients given SC rhIL-15 (with concurrent neurologic toxicity in 5 of 9 patients) and was responsive to steroids and tocilizumab. SC administration was associated with slower pharmacokinetic clearance and higher levels of IL-6 than IV dosing. These novel trials testing the use of IL-15 to potentiate cell therapy suggest that dosing schedules based on pharmacokinetics and pharmacodynamics will preserve the therapeutic benefits of IL-15 and minimize CRS. These trials were registered at www.clinicaltrials.gov as #NCT01385423 and #NCT02395822.

Haploidentical natural killer cells induce remissions in non-Hodgkin lymphoma patients with low levels of immune-suppressor cells.

We report a novel phase 2 clinical trial in patients with poor prognosis refractory non-Hodgkin lymphoma (NHL) testing the efficacy of haploidentical donor natural killer (NK) cell therapy (NK dose 0.5-3.27 × 107 NK cells/kg) with rituximab and IL-2 (clinicaltrials.gov NCT01181258). Therapy was tolerated without graft-versus-host disease, cytokine release syndrome, or neurotoxicity. Of 14 evaluable patients, 4 had objective responses (29%; 95% CI 12-55%) at 2 months: 2 had complete response lasting 3 and 9 months. Circulating donor NK cells persisted for at least 7 days after infusion at the level 0.6-16 donor NK cells/µl or 0.35-90% of total CD56 cells. Responding patients had lower levels of circulating host-derived Tregs (17 ± 4 vs. 307 ± 152 cells/µL; p = 0.008) and myeloid-derived suppressor cells at baseline (6.6 ± 1.4% vs. 13.0 ± 2.7%; p = 0.06) than non-responding patients. Lower circulating Tregs correlated with low serum levels of IL-10 (R 2 = 0.64; p < 0.003; n = 11), suggestive of less immunosuppressive milieu. Low expression of PD-1 on recipient T cells before therapy was associated with response. Endogenous IL-15 levels were higher in responders than non-responding patients at the day of NK cell infusion (mean ± SEM: 30 ± 4; n = 4 vs. 19.0 ± 4.0 pg/ml; n = 8; p = 0.02) and correlated with day 14 NK cytotoxicity as measured by expression of CD107a (R 2 = 0.74; p = 0.0009; n = 12). In summary, our observations support development of donor NK cellular therapies for advanced NHL as a strategy to overcome chemoresistance. Therapeutic efficacy may be further improved through disruption of the immunosuppressive environment and infusion of exogenous IL-15.

Optimization of cGMP purification and expansion of umbilical cord blood-derived T-regulatory cells in support of first-in-human clinical trials.

BACKGROUND AIMS: Thymic-derived regulatory T cells (tTreg) are critical regulators of the immune system. Adoptive tTreg transfer is a curative therapy for murine models of autoimmunity, graft rejection, and graft-versus-host disease (GVHD). We previously completed a "first-in-human" clinical trial using in vitro expanded umbilical cord blood (UCB)-derived tTreg to prevent GVHD in patients undergoing UCB hematopoietic stem cell transplantation (HSCT). tTreg were safe and demonstrated clinical efficacy, but low yield prevented further dose escalation. METHODS: To optimize yield, we investigated the use of KT64/86 artificial antigen presenting cells (aAPCs) to expand tTreg and incorporated a single re-stimulation after day 12 in expansion culture. RESULTS: aAPCs increased UCB tTreg expansion greater than eightfold over CD3/28 stimulation. Re-stimulation with aAPCs increased UCB tTreg expansion an additional 20- to 30-fold. Re-stimulated human UCB tTreg ameliorated GVHD disease in a xenogeneic model. Following current Good Manufacturing Practice (cGMP) validation, a trial was conducted with tTreg. tTreg doses up to >30-fold higher compared with that obtained with anti-CD3/28 mAb coated-bead expansion and Foxp3 expression was stable during in vitro expansion and following transfer to patients. Increased expansion did not result in a senescent phenotype and GVHD was significantly reduced. DISCUSSION: Expansion culture with cGMP aAPCs and re-stimulation reproducibly generates sufficient numbers of UCB tTreg that exceeds the numbers of T effector cells in an UCB graft. The methodology supports future tTreg banking and is adaptable to tTreg expansion from HSC sources. Furthermore, because human leukocyte antigen matching is not required, allogeneic UCB tTreg may be a useful strategy for prevention of organ rejection and autoimmune disease.

Postthaw characterization of umbilical cord blood: markers of storage lesion.

BACKGROUND: The continued growth in the uses of umbilical cord blood (UCB) will require the development of meaningful postthaw quality assays. This study examines both conventional and new measures for assessing UCB quality after long-term storage. STUDY DESIGN AND METHODS: The first arm of the study involved thawing UCB in storage for short (approx. 1 year) and long periods of time (>11 years). Conventional postthaw measures (colony-forming units [CFU], total nucleated cell counts, CD34+45+) were quantified in addition to apoptosis. The second arm of the study involved taking units stored in liquid nitrogen and imposing a storage lesion by storing the units in -80°C for various periods of time. After storage lesion, the units were thawed and assessed. RESULTS: In the first arm of the study, there was little difference in the postthaw measures between UCB stored for short and long periods of time. There was a slight increase in the percentage of CD34+45+ cells with time in storage and a reduction in the number of cells expressing apoptosis markers. When moved from liquid nitrogen to -80°C storage, the nucleated cell count varied little but there was a distinct decrease in frequency of CFUs and increase in percentage of cells expressing both early and late markers of apoptosis. CONCLUSION: Nucleated cell counts do not reflect damage to hematopoietic progenitors during long-term storage. Expression of caspases and other markers of apoptosis provide an early biomarker of damage during storage, which is consistent with other measures such as CFU and percentage of CD34+45+ cells.

Randomized phase II study of IL-2 with or without an allogeneic large multivalent immunogen vaccine for the treatment of stage IV melanoma.

OBJECTIVE: To evaluate the activity of interleukin-2 (IL-2) in combination with allogeneic large multivalent immunogen (LMI) vaccine, prepared by immobilizing SK23-CD80 melanoma cell line plasma membrane on 5-µm-diameter silica beads, in patients with melanoma. METHODS: Twenty-one patients with metastatic melanoma were randomly assigned to an IL-2 alone control group or an IL-2 plus LMI vaccine treatment group. The primary objective was to evaluate the progression-free survival (PFS) of each group. Secondary clinical objectives included median overall survival (OS) and 1- and 2-year rates of OS. RESULTS: Treatment was very well tolerated. Median PFS was no different between the treatment arm (2.20 mo) and control arm (1.95 mo). Median OS was also similar for the treatment arm (11.89 mo) and control arm (9.97 mo). CONCLUSIONS: This study failed to demonstrate that allogeneic LMI vaccine and low-dose IL-2 improved survival in patients with melanoma as compared with low-dose IL-2 alone.

Prevention of graft-versus-host disease by adoptive T regulatory therapy is associated with active repression of peripheral blood Toll-like receptor 5 mRNA expression.

Acute graft-versus-host disease (GVHD) occurs in 40% to 60% of recipients of partially matched umbilical cord blood transplantation (UCBT). In a phase I study, adoptive transfer of expanded CD4(+)CD25(+)Foxp3(+) natural regulatory T cells (nTregs) resulted in a reduced incidence of grade II-IV acute GVHD. To investigate potential mechanisms responsible for the reduced GVHD risk, we analyzed peripheral blood mononuclear cell mRNA expression of a tolerance gene set previously identified in operation- tolerant kidney transplant recipients, comparing healthy controls and patients who received nTregs and those who did not receive nTregs with and without experiencing GVHD. Samples from patients receiving nTregs regardless of GVHD status showed increased expression of Foxp3 expression, as well as B cell-related tolerance marker. This was correlated with early B cell recovery, predominately of naïve B cells, and nearly normal T cell reconstitution. CD8(+) T cells showed reduced signs of activation (HLA-DR(+) expression) compared with conventionally treated patients developing GVHD. In contrast, patients with GVHD had significantly increased TLR5 mRNA expression, whereas nTreg-treated patients without GVHD had reduced TLR5 mRNA expression. We identified Lin(-)HLADR(-)CD33(+)CD16(+) cells and CD14(++)CD16(-) monocytes as the main TLR5 producers, especially in samples of conventionally treated patients developing GVHD. Taken together, these data reveal interesting similarities and differences between tolerant organ and nTreg-treated hematopoietic stem cell transplantation recipients.

The autoimmunity-associated gene PTPN22 potentiates toll-like receptor-driven, type 1 interferon-dependent immunity.

Immune cells sense microbial products through Toll-like receptors (TLR), which trigger host defense responses including type 1 interferons (IFNs) secretion. A coding polymorphism in the protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene is a susceptibility allele for human autoimmune and infectious disease. We report that Ptpn22 selectively regulated type 1 IFN production after TLR engagement in myeloid cells. Ptpn22 promoted host antiviral responses and was critical for TLR agonist-induced, type 1 IFN-dependent suppression of inflammation in colitis and arthritis. PTPN22 directly associated with TNF receptor-associated factor 3 (TRAF3) and promotes TRAF3 lysine 63-linked ubiquitination. The disease-associated PTPN22W variant failed to promote TRAF3 ubiquitination, type 1 IFN upregulation, and type 1 IFN-dependent suppression of arthritis. The findings establish a candidate innate immune mechanism of action for a human autoimmunity "risk" gene in the regulation of host defense and inflammation.

Autocrine IFN-γ promotes naive CD8 T cell differentiation and synergizes with IFN-α to stimulate strong function.

Autocrine IFN-γ signaling is important for CD4 differentiation to Th1 effector cells, but it has been unclear whether it contributes to CD8 T cell differentiation. We show in this paper that naive murine CD8 T cells rapidly and transiently produce low levels of IFN-γ upon stimulation with Ag and B7-1, with production peaking at ∼8 h and declining by 24 h. The autocrine IFN-γ signals for upregulation of expression of T-bet and granzyme B and induces weak cytolytic activity and effector IFN-γ production. IFN-α acts synergistically with IFN-γ to support development of strong effector functions, whereas IL-12 induces high T-bet expression and strong function in the absence of IFN-γ signaling. Thus, IFN-γ is not only an important CD8 T cell effector cytokine, it is an autocrine/paracrine factor whose contributions to differentiation vary depending on whether the response is supported by IL-12 or type I IFN.

Blocking IL-21 signaling ameliorates xenogeneic GVHD induced by human lymphocytes.

In rodent graft-versus-host disease (GVHD) models, anti-IL-21 neutralizing mAb treatment ameliorates lethality and is associated with decreases in Th1 cytokine production and gastrointestinal tract injury. GVHD prevention was dependent on the in vivo generation of donor-inducible regulatory T cells (Tregs). To determine whether the IL-21 pathway might be targeted for GVHD prevention, skin and colon samples obtained from patients with no GVHD or grade 2 to 4 GVHD were analyzed for IL-21 protein expression. By immunohistochemistry staining, IL-21 protein-producing cells were present in all gastrointestinal tract samples and 54% of skin samples obtained from GVHD patients but not GVHD-free controls. In a human xenogeneic GVHD model, human IL-21-secreting cells were present in the colon of GVHD recipients and were associated with elevated serum IL-21 levels. A neutralizing anti-human IL-21 mAb given prophylactically significantly reduced GVHD-associated weight loss and mortality, resulting in a concomitant increase in Tregs and a decrease in T cells secreting IFN-γ or granzyme B. Based on these findings, anti-IL-21 mAb could be considered for GVHD prevention in the clinic.

Inflammatory cytokines as a third signal for T cell activation.

CD8 T cells require a third signal, along with Ag and costimulation, to make a productive response and avoid death and/or tolerance induction. Recent studies indicate that IL-12 and Type I IFN (IFNalpha/beta) are the major sources of signal 3 in a variety of responses, and that the two cytokines stimulate a common regulatory program involving altered expression of about 350 genes. Signal 3-driven chromatin remodeling is likely to play a major role in this regulation. Although less well studied, there is emerging evidence that CD4 T cells may also require a 'third signal' for a productive response and that IL-1 can provide this signal. Signal 3 cytokines can replace adjuvants in supporting in vivo T cell responses to peptide and protein antigens, and a better understanding of their activities and mechanisms should contribute to more rational design of vaccines.

Gene regulation and chromatin remodeling by IL-12 and type I IFN in programming for CD8 T cell effector function and memory.

A third signal that can be provided by IL-12 or type I IFN is required for differentiation of naive CD8 T cells responding to Ag and costimulation. The cytokines program development of function and memory within 3 days of initial stimulation, and we show here that programming involves regulation of a common set of approximately 355 genes including T-bet and eomesodermin. Much of the gene regulation program is initiated in response to Ag and costimulation within 24 h but is then extinguished unless a cytokine signal is available. Histone deacetylase inhibitors mimic the effects of IL-12 or type I IFN signaling, indicating that the cytokines relieve repression and allow continued gene expression by promoting increased histone acetylation. In support of this, increased association of acetylated histones with the promoter loci of granzyme B and eomesodermin is shown to occur in response to IL-12, IFN-alpha, or histone deacetylase inhibitors. Thus, IL-12 and IFN-alpha/beta enforce in common a complex gene regulation program that involves, at least in part, chromatin remodeling to allow sustained expression of a large number of genes critical for CD8 T cell function and memory.

Programming for CD8 T cell memory development requires IL-12 or type I IFN.

Inflammation can have both positive and negative effects on development of CD8 T cell memory, but the relative contributions and cellular targets of the cytokines involved are unclear. Using CD8 T cells lacking receptors for IL-12, type I IFN, or both, we show that these cytokines act directly on CD8 T cells to support memory formation in response to vaccinia virus and Listeria monocytogenes infections. Development of memory to vaccinia is supported predominantly by IL-12, whereas both IL-12 and type I IFN contribute to memory formation in response to Listeria. In contrast to memory formation, the inability to respond to IL-12 or type I IFN had a relatively small impact on the level of primary expansion, with at most a 3-fold reduction in the case of responses to Listeria. We further show that programming for memory development by IL-12 is complete within 3 days of the initial naive CD8 T cell response to Ag. This programming does not result in formation of a population that expresses killer cell lectin-like receptor G1, and the majority of the resulting memory cells have a CD62L(high) phenotype characteristic of central memory cells. Consistent with this, the cells undergo strong expansion upon rechallenge and provide protective immunity. These data demonstrate that IL-12 and type I IFN play an essential early role in determining whether Ag encounter by naive CD8 T cells results in formation of a protective memory population.

Autologous large multivalent immunogen vaccine in patients with metastatic melanoma and renal cell carcinoma.

OBJECTIVE: To evaluate the safety and activity of large multivalent immunogen (LMI), prepared by immobilizing autologous tumor cell plasma membrane on 5-microm diameter silica beads, in patients with melanoma and renal cell carcinoma (RCC). METHODS: Thirty patients with stage IV metastatic melanoma and 31 patients with stage IV RCC were randomly assigned to 1 of 3 trial arms and received monthly treatment with (1) LMI alone, (2) cyclophosphamide followed 8 days later with LMI, or (3) the same treatment as in arm 2 with IL-2 given for 5 days beginning 1 week after LMI administration. RESULTS: No grade 4 toxicities were observed. For patients with melanoma, median overall survival time for all 30 patients was 20.4 months [95% confidence interval (CI): 8.0-not assessable], and median progression-free survival was 2.8 months (95% CI: 1.9-6.3). For patients with RCC, median overall survival exceeded 46.2 months (95% CI: 30.3-not assessable), and median progression-free survival was 12.2 months (95% CI: 4.6-not assessable). Two patients had a partial response to LMI treatment. CONCLUSIONS: Based on our results that demonstrate the safety and tolerability of LMI vaccine, further development of this therapy is warranted to evaluate its clinical efficacy.

Activation-induced non-responsiveness (anergy) limits CD8 T cell responses to tumors.

Naïve CD8 T cells respond to signals provided by Ag, costimulation and cytokines by proliferating and differentiating to develop effector functions. Following initial clonal expansion, however, the cells develop activation-induced non-responsiveness (AINR), a form of anergy characterized by an inability to produce IL-2. Cells in the AINR state can carry out effector functions (cytolysis, IFN-gamma production) but cannot continue to proliferate and expand in the face of persisting Ag. AINR limits the ability of activated CTL to control tumor growth but can be reversed by IL-2, provided either therapeutically or by activated CD4 T helper cells, to allow continued expansion.

The CD8 T cell response to vaccinia virus exhibits site-dependent heterogeneity of functional responses.

CD8 T cell responses to vaccinia virus (VV) and a virus-encoded ovalbumin peptide (OVAP) epitope were examined using adoptively transferred OT-I T cells. The results demonstrate that upon intra-peritoneal challenge with ovalbumin-expressing VV (VV-OVAP), OT-I T cell proliferation occurs initially in lymph nodes and spleens followed by migration of the divided cells to the peritoneal cavity. Massive clonal expansion occurs in response to both the virus and the virus-encoded ovalbumin (OVA) epitope, as demonstrated using low numbers of adoptively transferred cells, and the responding OT-I cells display marked site-dependent functional heterogeneity with respect to IFN-gamma and tumor necrosis factor-alpha (TNF-alpha) production and granzyme B expression. OT-I cells responding to VV-OVAP develop the capacity to produce IFN-gamma in response to antigen as they proliferate and differentiate. In marked contrast, naive OT-I cells rapidly produce TNF-alpha upon antigen recognition, and this capacity declines as the cells proliferate in response to the virus, suggesting that this potent inflammatory cytokine may be important primarily during initiation of the response. At the peak of clonal expansion, a large fraction (30-60%) of the OT-I cells responding to the virus express high IL-7Ralpha levels, and the majority of these cells is subsequently lost. While high IL-7Ralpha expression may be necessary for a CD8 T cell to transition to memory, it is clearly not sufficient. Thus, OT-I cells responding to VV infection exhibit a high degree of heterogeneity within the responding population that differs depending on their anatomical location, despite the specificity and affinity of the TCR being identical on all of the cells.

Signal 3 availability limits the CD8 T cell response to a solid tumor.

CD8 T cells need a third signal, along with Ag and costimulation, for effective survival and development of effector functions, and this can be provided by IL-12 or type I IFN. Adoptively transferred OT-I T cells, specific for H-2K(b) and OVA, encounter Ag in the draining lymph nodes of mice with the OVA-expressing E.G7 tumor growing at a s.c. site. The OT-I cells respond by undergoing limited clonal expansion and development of effector functions (granzyme B expression and IFN-gamma production), and they migrate to the tumor where they persist but fail to control tumor growth. In contrast, OT-I T cells deficient for both the IL-12 and type I IFN receptors expand only transiently and rapidly disappear. These results suggested that some signal 3 cytokine is available, but that it is insufficient to support a CTL response that can control tumor growth. Consistent with this, administration of IL-12 at day 10 of tumor growth resulted in a large and sustained expansion of wild-type OT-I cells with enhanced effector functions, and tumor growth was controlled. This did not occur when the OT-I cells lacked the IL-12 and type I IFN receptors, demonstrating that the therapeutic effect of IL-12 results from direct delivery of signal 3 to the CD8 T cells responding to tumor Ag in the signal 3-deficient environment of the tumor.

Molecular basis for checkpoints in the CD8 T cell response: tolerance versus activation.

CD8 T cells specific for self-antigens are present in the peripheral lymphoid system and can contribute to autoimmunity or transplant rejection. Whether recognition of Ag leads to full activation, or to induction of tolerance, depends upon availability of cytokine at critical stages of the response. Signals provided by IL-12 and/or IFN-alpha/beta are required for activation of naïve CD8 T cells, and IL-2 is needed to sustain and further expand the effector cells if Ag persists. These critical signaling requirements provide new insights into the factors that regulate the CD8 T cell contributions to development of autoimmunity or rejection of transplants.

Signals required for programming effector and memory development by CD8+ T cells.

Stimulation of naïve CD8+ T cells with antigen and costimulation results in proliferation and weak clonal expansion, but the cells fail to develop effector functions and are tolerant long term. Initiation of the program leading to the strong expansion and development of effector functions and memory requires a third signal that can be provided by interleukin-12 (IL-12) or interferon-alpha (IFN-alpha). CD4+ T cells condition dendritic cells (DCs) to effectively present antigen to CD8+ T cells, and this conditioning involves, at least in part, CD40-dependent upregulation of the production of these signal 3 cytokines by the DCs. Upon being fully activated, the cytotoxic T lymphocytes develop activation-induced non-responsiveness (AINR), a form of split anergy characterized by an inability to produce IL-2 to support continued expansion. If antigen remains present, IL-2 provided by CD4+ T cells can reverse AINR to allow further expansion of the effector population and conversion to responsive memory cells following antigen clearance. If IL-2 or potentially other proliferative signals are not available, persistent antigen holds cells in the AINR state and prevents the development of a responsive memory population. Thus, in addition to antigen and costimulation, CD8+ T cells require cytokine signals at distinct stages of the response to be programmed for optimal generation of effector and memory populations.

Signal 3 tolerant CD8 T cells degranulate in response to antigen but lack granzyme B to mediate cytolysis.

Naive CD8 T cells that respond in vivo to Ag and costimulation in the absence of a third signal, such as IL-12, fail to develop cytolytic function and become tolerized. We show in this study that CD8 T cells purified from TCR transgenic mice and stimulated in vitro in the presence or absence of IL-12 form conjugates with specific target cells, increase intracellular Ca2+, and undergo degranulation to comparable extents. Perforin is also expressed at comparable levels in the absence or presence of a third signal, but expression of granzyme B depends upon IL-12. Levels of granzyme B also correlate strongly with the cytolytic activity of cells responding in vivo. In contrast, an increase in CD107a (lysosomal-associated membrane protein 1) expression resulting from degranulation cannot distinguish in vivo generated lytic effector cells from tolerized, noncytolytic cells. Thus, it appears that cells rendered tolerant as a result of stimulation in the absence of a third signal fail to lyse target cells because they are "shooting blanks."

CD4 T cell-dependent conditioning of dendritic cells to produce IL-12 results in CD8-mediated graft rejection and avoidance of tolerance.

Rejection of ectopic heart transplants expressing OVA requires OVA-specific CD4 and CD8 T cells. In the absence of CD4 T cells, OVA-specific CD8 T cells proliferate and migrate to the graft, but fail to develop cytolytic functions. With CD4 T cells present, clonal expansion of the CD8 T cells is only marginally increased but the cells now develop effector functions and mediate rapid graft rejection. In the presence of CD4 T cells, Ag and B7 levels do not increase on dendritic cells but IL-12 production is up-regulated, and this requires CD154 expression on the CD4 T cells. OVA-specific CD8 T cells lacking the IL-12 receptor fail to differentiate or mediate graft rejection even when CD4 T cells are present. Thus, CD4 T cells condition dendritic cells by inducing the production of IL-12, which is needed as the "third signal" for CD8 T cell differentiation and avoidance of tolerance.