Histamine dihydrochloride and low-dose interleukin-2 as post-consolidation immunotherapy in acute myeloid leukemia

Can histamine cause an enhancement of the cellular uptake and cytotoxicity of doxorubicin-loaded polylactide nanoparticles?

Histamine (His) in humans is physiologically involved in neurotransmission and increases vascular permeability during the development of inflammatory response and immunity. It could be used to enhance drug-loaded nanoparticles (NPs) distribution. However, it cannot be freely delivered due to the risk of His-dose-dependent deleterious effects. His can be attached to the polymeric backbone during polymerization to overcome this limitation. In this study, His was used as an initiator of lactide polymerization, and the obtained macromolecules were subsequently used to prepare doxorubicin (DOX)-loaded NPs by nanoprecipitation and microfluidics for examination of anti-cancer properties. Notably, the in vitro activity towards gastric cancer cells (AGS) of the NPs composed of histamine-functionalized polylactides (PLAs) was greatly enhanced compared to control NPs built from hydroxy‑functionalized PLAs. Furthermore, Zonula occludens-1 (ZO-1) tight junction protein production was significantly diminished after treating cells with DOX-loaded NPs assembled with PLAs with histamine residues. These results demonstrate the synergistic effect in cytotoxicity towards gastric cancer cells of DOX and the histamine that are carried by NPs. It is believed that His-DOX NPs strategy may lead to effective, targeted, and low-toxic delivery of drugs into cancer cells.

Histamine in cancer immunology and immunotherapy. Current status and new perspectives

Cancer is the second leading cause of death globally and its incidence and mortality are rapidly increasing worldwide. The dynamic interaction of immune cells and tumor cells determines the clinical outcome of cancer. Immunotherapy comes to the forefront of cancer treatments, resulting in impressive and durable responses but only in a fraction of patients. Thus, understanding the characteristics and profiles of immune cells in the tumor microenvironment (TME) is a necessary step to move forward in the design of new immunomodulatory strategies that can boost the immune system to fight cancer. Histamine produces a complex and fine-tuned regulation of the phenotype and functions of the different immune cells, participating in multiple regulatory responses of the innate and adaptive immunity. Considering the important actions of histamine-producing immune cells in the TME, in this review we first address the most important immunomodulatory roles of histamine and histamine receptors in the context of cancer development and progression. In addition, this review highlights the current progress and foundational developments in the field of cancer immunotherapy in combination with histamine and pharmacological compounds targeting histamine receptors.

Pathogenic and therapeutic roles of cytokines in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease with high mortality that accounts for the most common acute leukemia in adults. Despite all progress in the therapeutic strategies and increased rate of complete remission, many patients will eventually relapse and die from the disease. Cytokines as molecular messengers play a pivotal role in the immune system. The imbalance release of cytokine has been shown to exert a significant influence on the progression of hematopoietic malignancies including acute myeloid leukemia. This article aimed to summarize current knowledge about cytokines and their critical roles in the pathogenesis, treatment, and survival of AML patients.

MRP4/ABCC4 expression is regulated by histamine in acute myeloid leukemia cells, determining cAMP efflux

Intracellular cAMP (i-cAMP) levels play an important role in acute myeloid leukemia (AML) cell proliferation and differentiation. Its levels are the result of cAMP production, degradation, and exclusion. We have previously described histamine H₂ receptors and MRP4/ABCC4 as two potential targets for AML therapy. Acting through histamine H₂ receptors, histamine increases cAMP production/synthesis, while MRP4/ABCC4 is responsible for the exclusion of this cyclic nucleotide. In this study, we show that histamine treatment induces MRP4/ABCC4 expression, augmenting cAMP efflux, and that histamine, in combination with MRP inhibitors, is able to reduce AML cell proliferation. Histamine, through histamine H₂ receptor, increases i-cAMP levels and induces MRP4 transcript and protein levels in U937, KG1a, and HL-60 cells. Moreover, histamine induces MRP4 promoter activity in HEK293T cells transfected with histamine H₂ receptor (HEK293T-H₂ R). Our results support that the cAMP/Epac-PKA pathway, and not MEK/ERK nor PI3K/AKT signaling cascades, is involved in histamine-mediated upregulation of MRP4 levels. Finally, the addition of histamine potentiates the inhibition of U937, KG1a, and HL-60 cell proliferation induced by MRP4 inhibitors. Our data highlight that the use of a poly-pharmacological approach aimed at different molecular targets would be beneficial in AML treatment.

Anti-Leukemic Properties of Histamine in Monocytic Leukemia: The Role of NOX2

In patients with acute myeloid leukemia (AML), treatment with histamine dihydrochloride (HDC) and low-dose IL-2 (HDC/IL-2) in the post-chemotherapy phase has been shown to reduce the incidence of leukemic relapse. The clinical benefit of HDC/IL-2 is pronounced in monocytic forms of AML, where the leukemic cells express histamine type 2 receptors (H2R) and the NAPDH oxidase-2 (NOX2). HDC ligates to H2Rs to inhibit NOX2-derived formation of reactive oxygen species, but details regarding the anti-leukemic actions of HDC remain to be elucidated. Here, we report that human NOX2+ myelomonocytic/monocytic AML cell lines showed increased expression of maturation markers along with reduced leukemic cell proliferation after exposure to HDC in vitro. These effects of HDC were absent in corresponding leukemic cells genetically depleted of NOX2 (NOX2-/-). We also observed that exposure to HDC altered the expression of genes involved in differentiation and cell cycle progression in AML cells and that these effects required the presence of NOX2. HDC promoted the differentiation also of primary monocytic, but not non-monocytic, AML cells in vitro. In a xenograft model, immunodeficient NOG mice were inoculated with wild-type or NOX2-/- human monocytic AML cells and treated with HDC in vivo. The administration of HDC reduced the in vivo expansion of NOX2+/+, but not of NOX2-/- human monocytic AML cells. We propose that NOX2 may be a conceivable target in the treatment of monocytic AML.

Natural killer cells in acute myeloid leukemia patients: from phenotype to transcriptomic analysis

Chemotherapies allow complete remission in more than 50 % of patients with acute myeloid leukemia (AML), however, with frequent relapse. This suggests that residual leukemic cells may escape to chemotherapy and immune system. Natural killer (NK) cells from AML patients (AML-NK) have a weaker natural cytotoxicity-activating receptors (NCRs) expression than NK cells from healthy donors (HD-NK). Coding genes for NCR1/NKp46, NCR2/NKp44 and NCR3/NKp30 are located at different loci on two different chromosomes; however, their expression is tightly coordinated. Most NK cells express either high (NCR^bright) or low levels (NCR^dull) of all three NCRs. This suggests the existence of negative/positive regulation factor(s) common to the three receptors. In order to find transcription factor(s) or pathway(s) involved in NCRs co-regulation, this study compared the transcriptomic signature of HD-NK and AML-NK cells, before and after in vitro NK cells culture. Microarrays analysis revealed a specific NK cells transcriptomic signature in patients with AML. However, in vitro NK cells expansion erased this signature and up-regulated expression of central molecules of NK functions, such as NCR, NKG2D and also ETS-1, regardless of their origin, i.e., AML-NK vs HD-NK. ETS-1 transcription factor was shown to bind to a specific and common region in the NCRs promoters, thus appearing as a good candidate to explain the coordinated regulation of three NCRs. Such results are encouraging regarding in vitro AML-NK cytotoxicity restoration and provide a new conceptual support for innovative cellular therapy based on in vitro NK cells expansion before their reinfusion in AML patients.

Impact of killer-immunoglobulin-like receptor and human leukocyte antigen genotypes on the efficacy of immunotherapy in acute myeloid leukemia

Interactions between killer-immunoglobulin-like receptors (KIRs) and their HLA class I ligands are instrumental in natural killer (NK) cell regulation and protect normal tissue from NK cell attack. Human KIR haplotypes comprise genes encoding mainly inhibitory receptors (KIR A) or activating and inhibitory receptors (KIR B). A substantial fraction of humans lack ligands for inhibitory KIRs (iKIRs), that is, a ‘missing ligand’ genotype. KIR B/x and missing ligand genotypes may thus give rise to potentially autoreactive, unlicensed NK cells. Little is known regarding the impact of such genotypes in untransplanted acute myeloid leukemia (AML). For this study, NK cell phenotypes and KIR/HLA genotypes were determined in 81 AML patients who received immunotherapy with histamine dihydrochloride and low-dose IL-2 for relapse prevention (NCT01347996). We observed that presence of unlicensed NK cells impacted favorably on clinical outcome, in particular among patients harboring functional NK cells reflected by high expression of the natural cytotoxicity receptor (NCR) NKp46. Genotype analyses suggested that the clinical benefit of high NCR expression was restricted to patients with a missing ligand genotype and/or a KIR B/x genotype. These data imply that functional NK cells are significant anti-leukemic effector cells in patients with KIR/HLA genotypes that favor NK cell autoreactivity.

Dynamics of cytotoxic T cell subsets during immunotherapy predicts outcome in acute myeloid leukemia

Preventing relapse after chemotherapy remains a challenge in acute myeloid leukemia (AML). Eighty-four non-transplanted AML patients in first complete remission received relapse-preventive immunotherapy with histamine dihydrochloride and low-dose interleukin-2 in an international phase IV trial (ClinicalTrials.gov; NCT01347996). Blood samples were drawn during cycles of immunotherapy and analyzed for CD8+ (cytotoxic) T cell phenotypes in blood. During the first cycle of therapy, a re-distribution of cytotoxic T cells was observed comprising a reduction of T effector memory cells and a concomitant increase of T effector cells. The dynamics of T cell subtypes during immunotherapy prognosticated relapse and survival, in particular among older patients and remained significantly predictive of clinical outcome after correction for potential confounders. Presence of CD8+ T cells with specificity for leukemia-associated antigens identified patients with low relapse risk. Our results point to novel aspects of T cell-mediated immunosurveillance in AML and provide conceivable biomarkers in relapse-preventive immunotherapy.

Interleukin-2 as maintenance therapy for children and adults with acute myeloid leukaemia in first complete remission

BACKGROUND

Acute myeloid leukaemia (AML) is a malignant cancer of hematopoietic stem cells. The treatment of AML consists of two treatment phases: the remission induction phase to achieve a rapid, complete remission (CR) and the consolidation phase to achieve a durable molecular remission. People in CR are at risk of AML relapse, and people with relapsed AML have poor survival prospects. Thus, there is a continuous need for treatments to further improve prognosis. Interleukin-2 (IL-2), an immune-stimulatory cytokine, is an alternative to standard treatment for people with AML to maintain the efficacy after consolidation therapy. Maintenance therapy is not an integral part of the standard treatment for AML. Studies have been conducted to evaluate the efficacy of IL-2 as maintenance therapy for people with AML in first CR, but the effect of IL-2 is not yet fully established.

OBJECTIVES

To evaluate the efficacy and safety of IL-2 as maintenance therapy for children and adults with AML who have achieved first CR and have not relapsed.

SEARCH METHODS

We systematically searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library 2015, Issue 8), MEDLINE (1950 to August 2015), EMBASE (1950 to August 2015), LILACS (1982 to August 2015), CBM (1978 to August 2015), relevant conference proceedings (2000 to 2015), and metaRegister of Controlled Trials (since inception to August 2015) of ongoing and unpublished trials. In addition, we screened the reference lists of relevant trials and reviews.

SELECTION CRITERIA

Eligible studies were randomised controlled trials (RCTs) comparing IL-2 with no treatment in people with AML who had achieved first CR and had not relapsed. We did not identify studies comparing IL-2 versus best supportive care or maintenance chemotherapy or studies comparing IL-2 plus maintenance chemotherapy versus maintenance chemotherapy alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies, extracted data with a predefined extraction form, and assessed risk of bias of included studies. We extracted data on the following outcomes: disease-free survival, overall survival, event-free survival, treatment-related mortality, adverse events, and quality of life. We measured the treatment effect on time-to-event outcomes and dichotomous outcomes with hazard ratio (HR) and risk ratio, respectively. We used inverse-variance method to combine HRs with fixed-effect model unless there was significant between-study heterogeneity.

MAIN RESULTS

We included nine RCTs with a total of 1665 participants, comparing IL-2 with no treatment. Six studies included adult participants, and three studies included both adults and children. However, the latter three studies did not report data for children, thus we were unable to conduct subgroup analysis of children. One Chinese study did not report any outcomes of interest for this review. We included six trials involving 1426 participants in the meta-analysis on disease-free survival, and included five trials involving 1355 participants in the meta-analysis on overall survival. There is no evidence for difference between IL-2 group and no-treatment group regarding disease-free survival (HR 0.95; 95% CI 0.86 to 1.06, P = 0.37; quality of evidence: low) or overall survival (HR 1.05; 95% CI 0.95 to 1.16, P = 0.35; quality of evidence: moderate). Based on one trial of 161 participants, IL-2 exerted no effect on event-free survival (HR 1.02; 95% CI 0.79 to 1.32, P = 0.88; quality of evidence: low). Adverse events (including thrombocytopenia, neutropenia, malaise/fatigue, and infection/fever) were more frequent in participants receiving IL-2, according to one trial of 308 participants. No mortality due to adverse events was reported. None of the included studies reported treatment-related mortality or quality of life.

AUTHORS' CONCLUSIONS

There is no evidence for a difference between IL-2 maintenance therapy and no treatment with respect to disease-free survival or overall survival of people with AML in first CR; however, the quality of the evidence is moderate or low, and further research is likely or very likely to have an important impact on the estimate or our confidence in the estimate. Adverse events seem to be more frequent in participants treated with IL-2, but the quality of the evidence is very low and our confidence in the estimates is very uncertain. Thus, further prospective randomised trials are needed before definitive conclusions can be drawn on these issues.

High constitutive Akt2 activity in U937 promonocytes: effective reduction of Akt2 phosphorylation by the histamine H2-receptor and the β2-adrenergic receptor

Histamine (HA) is approved for the treatment of acute myeloid leukemia (AML). Its antileukemic activity is related to histamine H2-receptor (H2R)-mediated inhibition of reactive oxygen species (ROS) production in myeloid cells facilitating survival of antineoplastic lymphocytes. The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, which plays a crucial role in cell survival and proliferation, is constitutively activated in leukemic cells of most AML patients resulting in poor survival prognosis. In a proof-of-principle experiment using a human phosphorylated mitogen-activated protein kinase (MAPK) array, we found high phosphorylation levels of Akt2 in U937 promonocytes that was abrogated by HA or selective H2R agonists. The H2R and the β2-adrenergic receptor (β2AR) are Gs-protein-coupled receptors. Stimulation results in adenylyl cyclase activation followed by generation of the second messenger adenosine 3′,5′-cyclic monophosphate (cAMP). In our present study, we evaluated the pharmacological profile of the H2R and the β2AR regarding Akt2 phosphorylation at Ser474 via western blot analysis and ELISA and cAMP accumulation via HPLC-MS/MS in U937 promonocytes. H2R and β2AR agonists concentration-dependently decreased Akt2 phosphorylation at Ser474. Deviations of potencies and efficacies of agonists in Akt2 phosphorylation and cAMP accumulation assays indicated participation of cAMP-independent signaling in GPCR-induced reduction of Akt2 phosphorylation. Accordingly, our study supports the concept of functional selectivity of the H2R and the β2AR in U937 promonocytes. In summary, we extended the antileukemic mechanism of HA via H2R and revealed the potential of β2AR agonists, which are already approved in the treatment of bronchial asthma and chronic obstructive pulmonary disease, as antileukemic drugs.

Pharmacokinetic properties and safety profile of histamine dihydrochloride injection in Chinese healthy volunteers: a phase I, single-center, open-label, randomized study

PURPOSE

Histamine dihydrochloride (HDC) injection has been approved in Europe for the treatment of adults with acute myeloid leukemia, used in combination therapy with the T-cell-derived cytokine interleukin-2. Despite years of clinical applications of HDC in Europe, no data are available on its tolerability and pharmacokinetic properties in Chinese patients. The objective of this study was to determine the safety profile and pharmacokinetic properties of HDC in Chinese healthy volunteers (HVs).

METHODS

In this Phase I, single-center, open-label, randomized study, 20 Chinese HVs were randomized to receive a single dose of 0.5 or 1.0 mg HDC via a 10-minute subcutaneous injection. Whole-blood and urine samples were collected at designated time points after dosing. Plasma and urine concentrations of histamine and metabolite N-methyl histamine were measured using a validated HPLC-MS/MS method. Pharmacokinetic parameters were estimated through noncompartmental procedures based on concentration-time data. Adverse events and evaluation of clinical laboratory tests were used to assess the safety profile. The pharmacokinetic profile for a single-dose of 1.0 mg HDC in Chinese HVs was compared with that in Western HVs.

FINDINGS

No severe adverse events occurred in this study, and the severity of all adverse events was grade I according to the Common Terminology Criteria for Adverse Events, version 4.0. For the pharmacokinetic parameters of histamine at the 0.5-mg and 1.0-mg dose levels, t½ was 0.50 and 1.02 hours; Tmax was 0.15 and 0.14 hours; mean Cmax was 26.59 and 71.01 nmol/L; AUC0-t was 8.35 and 20.43 nmol/h/L; AUC0-∞ was 9.61 and 22.69 nmol/h/L; accumulated amount excreted in urine within 24 hours was 125.93 and 145.52 nmol; and maximum urine excretion rates were 21.85 and 38.94 nmol/h, respectively. For N-methyl histamine at the 0.5-mg and 1.0-mg dose levels, t½ was 0.58 and 0.66 hours; Tmax was 0.28 and 0.26 hours; mean Cmax was 17.01 and 23.54 nmol/L; AUC0-t was 7.72 and 17.08 nmol/h/L; AUC0-∞ was 9.01 and 19.62 nmol/h/L; accumulated amount excreted in urine within 24 hours was 331.7 and 583.21 nmol; and maximum urine excretion rates were 53.29 and 133.53 nmol/h, respectively.

IMPLICATIONS

Both single-dose 0.5 mg and 1.0 mg HDC were well tolerated in Chinese HVs, and the pharmacokinetic profile of HDC in Chinese HVs was characterized in this study. A single dose of 1.0 mg HDC had a more rapid but similar extent of absorption, a wider distribution, and a little more rapid elimination in Chinese HVs compared with Western HVs. Findings from this study support additional clinical trials for HDC using in Chinese patients. Chinese Clinical Trial Registry identifier: ChiCTR-ONC-13003954.

Optimal therapy for adult patients with acute myeloid leukemia in first complete remission

Although it is absolutely clear that postremission therapy is currently necessary to obtain disease-free long-term survivorship for patients with acute myeloid leukemia (AML) in first complete remission (CR), it is not entirely clear what form that treatment should take. High-dose cytarabine is clearly effective and there definitely is a dose-response relationship for cytarabine and remission duration. High-dose cytarabine is effective for younger patients but not elderly patients. It is effective for patients with favorable cytogenetics but it is not clear whether it is effective for patients with intermediate or unfavorable cytogenetics. Furthermore, it is not clear what the most effective and least toxic dose and schedule of high-dose cytarabine is.

Immunotherapeutic strategies for relapse control in acute myeloid leukemia

Despite that the initial phases of chemotherapy induce disappearance of leukemic cells in many patients with acute myeloid leukemia (AML), the prevention of life-threatening relapses in the post-remission phase remains a significant clinical challenge. Allogeneic bone marrow transplantation, which is available for a minority of patients, efficiently prevents recurrences of leukemia by inducing immune-mediated elimination of leukemic cells, and over the past decades, numerous immunotherapeutic protocols have been developed aiming to mimic the graft-versus-leukemia reaction for the prevention of relapse. Here we review past and present strategies for relapse control with focus on overcoming leukemia-related immunosuppression in AML. We envisage future treatment protocols, in which systemic immune activators, such as vaccines, dendritic cell-based therapies, engineered variants of IL-2, or IL-15, are combined with agents that counter immunosuppression mediated by, e.g., the PD/PDL interaction, CTLA-4, CD200, reactive oxygen species, IDO expression, CXCR4, or the KIR/class I interaction, based on characteristics of the prevailing malignant clone. This combinatorial approach may pave the way for individualized immunotherapy in AML.

Regulation of the immune response and inflammation by histamine and histamine receptors

Histamine is a biogenic amine with extensive effects on many cell types, including important immunologic cells, such as antigen-presenting cells, natural killer cells, epithelial cells, and T and B lymphocytes. Histamine and its 4 receptors represent a complex system of immunoregulation with distinct effects dependent on receptor subtypes and their differential expression. These are influenced by the stage of cell differentiation, as well as microenvironmental influences, leading to the selective recruitment of effector cells into tissue sites accompanied by effects on cellular maturation, activation, polarization, and effector functions, which lead to tolerogenic or proinflammatory responses. In this review we discuss the regulation of histamine secretion, receptor expression, and differential activation of cells within both the innate and adaptive immune responses. It is clear that the effects of histamine on immune homeostasis are dependent on the expression and activity of the 4 currently known histamine receptors, and we also recognize that 100 years after the original identification of this biogenic amine, we still do not fully understand the complex regulatory interactions between histamine and the host immune response to everyday microbial and environmental challenges.

Clinical evaluation of cellular immunotherapy in acute myeloid leukaemia

Immunotherapy is currently under active investigation as an adjuvant therapy to improve the overall survival of patients with acute myeloid leukaemia (AML) by eliminating residual leukaemic cells following standard therapy. The graft-versus-leukaemia effect observed following allogeneic haematopoietic stem cell transplantation has already demonstrated the significant role of immune cells in controlling AML, paving the way to further exploitation of this effect in optimized immunotherapy protocols. In this review, we discuss the current state of cellular immunotherapy as adjuvant therapy for AML, with a particular focus on new strategies and recently published results of preclinical and clinical studies. Therapeutic vaccines that are being tested in AML include whole tumour cells as an autologous source of multiple leukaemia-associated antigens (LAA) and autologous dendritic cells loaded with LAA as effective antigen-presenting cells. Furthermore, adoptive transfer of cytotoxic T cells or natural killer cells is under active investigation. Results from phase I and II trials are promising and support further investigation into the potential of cellular immunotherapeutic strategies to prevent or fight relapse in AML patients.