Preclinical Development and First-in-Human Study of KA2507, a Selective and Potent Inhibitor of Histone Deacetylase 6, for Patients with Refractory Solid Tumors.

PURPOSE: Inhibition of histone deacetylase 6 (HDAC6) is predicted to deliver both direct antitumor activity and modulation of the antitumor immune response. This study describes the development of a novel HDAC6 inhibitor. PATIENTS AND METHODS: KA2507 was characterized in HDAC biochemical and cellular target engagement assays and in preclinical efficacy models of melanoma and colorectal cancer. In a phase I study, KA2507 was administered orally using a 3+3 dose-escalation design (NCT03008018). RESULTS: KA2507 is a potent and selective inhibitor of HDAC6 (biochemical IC50 = 2.5 nmol/L). Preclinical models demonstrated antitumor efficacy in syngeneic tumor-bearing mice, with translational studies highlighting modulation of the antitumor immune response. Twenty patients were treated in a phase I study. KA2507 was well tolerated; dose-limiting toxicity was not observed up to the maximum dose administered. Pharmacokinetic profiling supported twice-daily oral dosing. Pharmacodynamic analysis demonstrated selective HDAC6 target engagement in peripheral blood cells, free from off-target class I HDAC activity. Stable disease was the best clinical response (7 patients). Three of these patients (adenoid cystic carcinoma, n = 2; rectal adenocarcinoma, n = 1) had prolonged disease stabilization that lasted for 16.4, 12.6, and 9.0 months, respectively. CONCLUSIONS: KA2507 is a potent and selective inhibitor of HDAC6 showing antitumor efficacy and immune modulatory effects in preclinical models. In a phase I study, KA2507 showed selective target engagement, no significant toxicities, and prolonged disease stabilization in a subset of patients. Further clinical studies of KA2507 are warranted, as a single agent or, preferably, combined with other immuno-oncology drugs.

The Histone Deacetylase Inhibitor Entinostat/Syndax 275 in Osteosarcoma.

The prognosis for metastatic osteosarcoma (OS) is poor and has not changed in several decades. Therapeutic paradigms that target and exploit novel molecular pathways are desperately needed. Recent preclinical data suggests that modulation of the Fas/FasL pathway may offer benefit in the treatment of refractory osteosarcoma. Fas and FasL are complimentary receptor-ligand proteins. Fas is expressed in multiple tissues, whereas FasL is restricted to privilege organs, such as the lung. Fas expression has been shown to inversely correlate with the metastatic potential of OS cells; tumor cells which express high levels of Fas have decreased metastatic potential and the ones that reach the lung undergo cell death upon interaction with constitutive FasL in the lung. Agents such as gemcitabine and the HDAC inhibitor, entinostat/Syndax 275, have been shown to upregulate Fas expression on OS cells, potentially leading to decreased OS pulmonary metastasis and improved outcome. Clinical trials are in development to evaluate this combination as a potential treatment option for patients with refractory OS.

Correction to: Monitoring of intracerebellarly-administered natural killer cells with fluorine-19 MRI.

There was a typo in author Andrew Wahba's name in the initial online publication. The original article has been corrected.

Monitoring of intracerebellarly-administered natural killer cells with fluorine-19 MRI.

PURPOSE: Medulloblastoma (MB) is the most common malignant brain tumor in children. Recent studies have shown the ability of natural killer (NK) cells to lyse MB cell lines in vitro, but in vivo successes remain elusive and the efficacy and fate of NK cells in vivo remain unknown. METHODS: To address these questions, we injected MB cells into the cerebellum of immunodeficient mice and examined tumor growth at various days after tumor establishment via bioluminescence imaging. NK cells were labeled with a fluorine-19 (19F) MRI probe and subsequently injected either intratumorally or contralaterally to the tumor in the cerebellum and effect on tumor growth was monitored. RESULTS: The 19F probe efficiently labeled the NK cells and exhibited little cytotoxicity. Fluorine-19 MRI confirmed the successful and accurate delivery of the labeled NK cells to the cerebellum of the mice. Administration of 19F-labeled NK cells suppressed MB growth, with the same efficacy as unlabeled cells. Immunohistochemistry confirmed the presence of NK cells within the tumor, which was associated with induction of apoptosis in tumor cells. NK cell migration to the tumor from a distal location as well as activation of apoptosis was also demonstrated by immunohstochemistry. CONCLUSIONS: Our results show that NK cells present a novel opportunity for new strategies in MB treatment. Further, 19F-labeled NK cells can suppress MB growth while enabling 19F MRI to provide imaging feedback that can facilitate study and optimization of therapeutic paradigms.

Effect of entinostat on NK cell-mediated cytotoxicity against osteosarcoma cells and osteosarcoma lung metastasis.

There is a crucial need for a new therapeutic approach for osteosarcoma (OS) lung metastasis since this disease remains the main cause of mortality in OS. We previously demonstrated that natural killer (NK) cell therapy has minimal efficacy against OS metastasis. This study determined whether the histone deacetylase inhibitor entinostat could immunosensitize OS cells to NK cell lysis and increases the efficacy of NK cell therapy for OS lung metastasis. Entinostat upregulated ligands for NK cell-activating receptors (major histocompatibility complex [MHC] class I polypeptide-related chain A [MICA] and B [MICB]; UL16 binding proteins 1, 2, 5, and 6; and CD155) on OS cells both in vitro and in vivo and led to more susceptibility to NK cell-mediated cytotoxicity in vitro. Importantly, entinostat did not change NK cell viability, receptor expression, or function within the 24-h treatment. We also demonstrated two potential mechanisms by which entinostat enhanced expression of MICA and MICB on OS cells. Although entinostat upregulated ligands for the NK cell activating receptor on OS lung metastasis, it failed to augment the efficacy of NK cell therapy in our nude mouse human OS lung metastasis model. This can be partly explained by our finding that although the infused NK cells were active and functional and could penetrate into the lungs, they failed to infiltrate into the lung nodules. These challenges regarding cellular immunotherapy against solid tumors may be overcome by combination therapy, such as adding a NK cell-activating cytokine (IL-2 or IL-21).

Aerosol Delivery of Interleukin-2 in Combination with Adoptive Transfer of Natural Killer Cells for the Treatment of Lung Metastasis: Methodology and Effect.

Natural killer (NK) cells are a subtype of lymphocytes with a major role as a host defense mechanism against tumor cells. Allogeneic NK cell therapy is being used as an alternative promising therapy for many different cancers. Interleukin-2 (IL-2) is a critical cytokine for NK cell proliferation, survival, and effector functions. Cytokine support is essential to activate, expand, and increase the life span of NK cells. Aerosol delivery of IL-2 in combination with adoptive transfer of NK cells offers a reasonable approach for the treatment of lung metastases as it avoids the deleterious side effects of systemic IL-2. Using a human OS mouse model, we demonstrated the efficacy of this approach. Combination therapy of aerosol IL-2 with NK cells resulted in a better therapeutic effect against OS lung metastases as compared with each therapy alone. Aerosol IL-2 selectively increased infiltration, retention, and proliferation of infused NK cells in the lung, and there was no local inflammation or toxicity in the lungs or any other organ. Our results demonstrate that delivery of IL-2 via the aerosol route offers a feasible and innovative approach to enhance the immunotherapeutic effect of NK cells against pulmonary metastases. In the following chapter, we describe the methodology and effect of this innovative therapeutic approach.

The narrow-spectrum HDAC inhibitor entinostat enhances NKG2D expression without NK cell toxicity, leading to enhanced recognition of cancer cells.

PURPOSE: Natural killer (NK) cell cytotoxicity correlates with the ligation of activating receptors (e.g., NKG2D) by their ligands (e.g., MHC class I-related chains [MIC] A and B) on target cells. Histone deacetylase inhibitors (HDACi) at high concentrations inhibit tumor growth and can increase NKG2D ligand expression on tumor targets, but are widely regarded as toxic to NK cells. METHODS: We investigated the mechanism of entinostat, a benzamide-derivative narrow-spectrum HDACi, in augmenting the cytotoxicity of NK cells against human colon carcinoma and sarcoma by assessing gene and protein expression, histone acetylation, and cytotoxicity in in vitro and murine models. RESULTS: We observed that entinostat dose- and time-dependent increase in MIC expression in tumor targets and NKG2D in primary human NK cells, both correlating with increased acetylated histone 3 (AcH3) binding to associated promoters. Entinostat pretreatment of colon carcinoma and sarcoma cells, NK cells, or both led to enhanced overall cytotoxicity in vitro, which was reversed by NKG2D blockade, and inhibited growth of tumor xenografts. Lastly, we showed decreased expression of MICA and ULBP2 transcription in primary human osteosarcoma. CONCLUSIONS: Entinostat enhances NK cell killing of cancer cells through upregulation of both NKG2D and its ligands, suggesting an attractive approach for augmenting NK cell immunotherapy of solid tumors such as colon carcinoma and sarcomas.

New immunological investigations on Helicobacter pylori-induced gastric ulcer in patients.

Although Helicobacter pylori (Hp) plays an important role in the pathogenesis of chronic gastritis and gastric ulcer, little is known about the probable mechanisms of these types of gastrointestinal damage. To determine the precise mechanisms involved in ulcer formation, immune responses in patients with gastric ulcer (GUP) caused by Hp infection (Hp(+)) were compared with those of other gastritis patients (GP). The sensitivity and proliferation of peripheral blood mononuclear cells (PBMNCs) obtained from patients were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against exposure with complex Hp crude antigen (HPCA) and mitogen (phytohemagglutinin, PHA). Production of inflammatory cytokines, including interleukin (IL)-1ß and IL-8, in serum and supernatants of PBMNCs were then measured by ELISA. It was found that, after stimulation with PHA, both IL-8 and IL-1ß concentrations in sera and supernatants as well as proliferation and sensitivity were statistically greater in GUP Hp(+) than GP Hp(-) . Furthermore, HPCA inhibited the proliferation of PBMNCs dose-dependently; however, it stimulated IL-8 and IL-1ß production in supernatants of mononuclear cells. Therefore, the up-regulated concentrations of IL-8 and IL-1ß may have been caused by increase in the size of mononuclear cell subpopulations or in their cytokine secretory activity, indicating the greatest cell responsiveness in GUP Hp(+) patients. These results suggest that tissue damage and ulcers occur in patients who produce more IL-8 and IL-1ß than patients who do not develop ulcers; the former consequently have more activated immune cells at the site of infection. Therefore, both host responses and Hp virulence factors may be involved in the development of gastric ulcers.

The role of IL15 gene variants in visceral leishmaniasis among Iranian patients.

The role of IL-15 in the protection against Leishmania (L) parasites has been clarified in previous studies, in which IL-15 similar to IFN-γ induces IL-12 production and stimulates the leishmaniacidal activity of the macrophages infected with L. infantum. Furthermore, the increased level of IL-15 in acute visceral leishmaniasis patients (VL) can suppress Th2 cytokines such as IL-4. Since different single nucleotide polymorphisms (SNPs) in the IL15 gene have been described, this study aimed to investigate the association of the SNPs at the positions 267, 367, 13,687 and 14,035 with VL. The IL15 gene variants were compared between two groups consisting of 117 VL patients and 146 healthy individuals using polymerase chain reaction-restriction fragment length polymorphism. The results showed that the frequencies of the alleles 267C (83.9 vs. 73.5%, P=0.0035), 13687A (22.4 vs. 12.8%, P=0.032), genotype 267CC (68.5 vs. 55.6%, P=0.031), haplotypes CGCA (16 vs. 8.3%, P=0.02) and TACA (11.2 vs. 4.8%, P=0.02) were significantly higher in the controls than those in the patients, while the genotypes 267TT (8.5 vs. 0.7%, P=0.0016), 13687CC (78.6 vs. 65.5%, P=0.015), the haplotypes TGCT (10 vs. 2.5%, P=0.00002) and TGCA (5.7 vs. 0.35%, P=0.000001) were significantly more frequent in the patients. In conclusion, it may be speculated that these gene variants with probable effects on the IL-15 production can serve as the factors influencing VL among Iranian population. However, to clarify the association of these variants with the level of IL-15, further studies are recommended.

Interleukin-17A genetic variants can confer resistance to brucellosis in Iranian population.

On the subject of brucellosis, it seems that Th1/Th2 cytokines balance may be involved in the resistance or susceptibility to Brucella infection. In this respect, Th1 cytokines confer resistance, while Th2 cytokines predispose brucellosis. It is also clarified that IL-17 is required for the induction of IFN-γ and IL-12 in macrophages and dendritic cells. Then, it seems that IL-17 can affect the induction of Th1 immunity which is necessary for controlling Brucella. In the present study, we tried to investigate probable relationship between IL-17A genetic variants and susceptibility to the human brucellosis. One hundred and seventy six patients with brucellosis and 84 healthy animal husbandmen, who consumed contaminated raw milk and dairy products from animals with brucellosis, were included in this study. All individuals were genotyped for 9 single nucleotide polymorphisms (SNPs) (rs4711998AG, rs8193036CT, rs3819024AG, rs2275913AG, rs3819025AG, rs8193038AG, rs3804513AT, rs1974226AG and rs3748067AG) being selected by using NCBI SNP database and literature using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The distribution of IL-17 rs4711998, rs8193038, rs3748067 AA genotypes and AAGAA haplotype were significantly more frequent in the patients than in the controls (P=0.008, 0.0019, 0.003 and 0.002, respectively) while IL-17 genotypes rs3819024GG and rs3819025AA were more frequent in the controls than the patients (P=0.001 and 0.0035, respectively). Based on the results, IL-17 rs4711998, rs8193038, rs3748067 AA genotypes and AAGAA haplotype could be considered as susceptibility factors for brucellosis while the inheritance of IL-17 rs3819024GG and rs3819025AA genotypes might be resistance factors against the disease.

Toll-like receptor 4 (TLR4) polymorphisms in Iranian patients with visceral leishmaniasis.

The role of Toll-like receptor (TLR) 4 in visceral leishmaniasis (VL), a disease caused by an obligate intracellular protozoan parasites belonging to the genus Leishmania, has been shown in the recent leishmaniasis experimental studies. As genetic host factors play an important role in the susceptibility and/or resistance to VL, the association between TLR4 gene mutations [A896G and C1196T single nucleotide polymorphisms (SNPs)] and VL was investigated. Genotyping of A896G (Asp299Gly) and C1196T (Thr399Ile) SNPs was performed in the patients with VL (N = 122) and ethnically matched controls (N = 155) using polymerase chain reaction-restriction fragment length polymorphism method. When VL patients and the controls were compared, no statistically significant differences were observed in A896G and C1196T alleles and genotypes (P > 0.05). The TLR4 A896G and C1196T were in moderate linkage disequilibrium in the controls and patients (r (2) = 0.497, 0.548 and D' = 0.705, 0.808, respectively), and haplotypes reconstructed from these SNPs were not significantly different between the aforementioned study groups. In conclusion, based on the results, TLR4 gene polymorphisms at the positions 896 and 1196 cannot be regarded as the major contributors to VL susceptibility among the Iranian population.

IL-1ß (-511T/C) gene polymorphism not IL-1ß (+3953T/C) and LT-α (+252A/G) gene variants confers susceptibility to visceral leishmaniasis.

Lymphotoxin-α (LT-α) and interleukin-1beta (IL-1ß) are proinflammatory cytokines playing important roles in immunity against Leishmania infection and the outcome of the disease. As cytokine productions are under the genetic control, this study tried to find any probable relationship between these cytokine gene polymorphisms and the susceptibility to visceral leishmaniasis in Iranian pediatric patients. Ninety-five pediatric patients involved with visceral leishmaniasis and 128 non-relative healthy people, from the same area as the patients, were genotyped for LT-α (+252A/G) and IL-1ß (+3953T/C and -511T/C) gene polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). There was not found any significant differences in allele and genotype frequencies of LT-α (+252A/G) and IL-1ß (+3953) among the study groups. However, the frequency of IL-1ß -511TT genotype was higher in the controls (P = 0.0004) while the frequency of IL-1ß -511CC genotype and C allele were higher in the patients (P = 0.008 and P = 0.00006, respectively). Furthermore, IL-1ß CC (-511/+3953) haplotype was more frequent in VL patients compared with the controls (P = 0.0002) and the distribution of TT haplotype was higher in the controls compared with the patients (P = 0.003). In conclusion, based on the results, IL-1ß -511C allele, CC genotype and CC (-511/+3953) haplotype could be considered as the susceptibility factors for visceral leishmaniasis while IL-1ß -511TT genotype, T allele and TT haplotype (-511/+3953) might be counted as the influential factors for resistance to the disease.

Interleukin-18 single nucleotide polymorphisms contribute to the susceptibility to brucellosis in Iranian patients.

It seems that IL-18 has a crucial role in immunity against Brucella infection. Since the expression of IL-18 can be affected by polymorphisms in its gene, we decided to investigate any probable relationship between the six different IL-18 gene polymorphisms and brucellosis. A total of 193 patients with brucellosis and 83 healthy farmers who consumed contaminated raw milk and dairy products from the animals with brucellosis, were included in this study. All the individuals were genotyped for six IL-18 polymorphisms at positions -656, -607, -137, +113, +127 and codon 35/3, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The distributions of alleles for IL-18 polymorphisms at positions -137G/+113T/+127C/codon 35/3A (correlated with higher production of IL-18) were significantly higher in healthy controls than in patients (P=0.012, 0.012, 0.012 and 0.0018, respectively). It could be suggested that individuals who inherited the aforementioned genotypes/alleles are able to produce higher levels of IL-18 at the onset of infection, and it leads to more IFN-gamma production and control Brucella infection before the emerging brucellosis.

Expression of recombinant heat-shock protein 70 of MCAN/IR/96/LON-49, a tool for diagnosis and future vaccine research.

BACKGROUND: Heat shock protein 70 (HSP70) is present in all organisms studied so far, and is a major immunogen in infections caused by pathogens including Leishmania spp. OBJECTIVE: The aim of this study was to clone and express HSP70 from L. infantum strain MCAN/IR/96/LON-49 and evaluate antibody response against HSP70 in visceral leishmaniasis (VL). METHODS: The L. infantum HSP70 gene segment was amplified by specific primers. It was cloned into pTZ57R vector and subcloned into pET32a (+) expression vector. The new construct was transformed in the E.coli Rosetta strain, and HSP70 protein was expressed in the presence of 1 mM IPTG and purified using a HiTrap chelating column. Antibody responses against HSP70 were determined by ELISA in 37 patients with visceral leishmaniasis and 63 healthy controls. RESULTS: Expression of HSP70 protein was confirmed using SDS-PAGE electrophoresis and dot blot with an anti-His tag antibody. There was no difference between the sequence of nucleotides of the HSP70 gene in the present study and other reported sequences. The ELISA results indicated that the sera of 81.1% (30/37) of the patients and 6.3% (5/63) of controls reacted to L. infantum HSP70. CONCLUSION: The conservative nature of the HSP70 molecule is an advantage in vaccine studies, because of minor differences (6%) between the nucleotide sequences and consequently the similarity in amino acid sequences in various strains of L. infantum. It could therefore be used in vaccine research against leishmaniasis and also as a tool for serodiagnosis.

Interleukin-10 gene polymorphisms and susceptibility to brucellosis in Iranian patients.

BACKGROUND: Interleukin-10 (IL-10) is a Th2-type cytokine that inhibits macrophage activation. It is known that production of IL-10 is affected by its gene promoter polymorphisms. OBJECTIVE: To investigate the relationship between IL-10 gene promoter polymorphisms and susceptibility to brucellosis. METHODS: One hundred and ninety patients with brucellosis and 81 healthy animal husbandmen who owned infected animals and consumed their contaminated dairy products were included in this study. All individuals were genotyped for three bi-allelic IL-10 gene promoter polymorphisms at positions -1082(G/A), -819(T/C), and -592(A/C) using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: The distribution of C alleles at positions -592 and -819 of IL-10 were significantly higher in patients than in the healthy animal husbandmen (p=0.034 and p=0.0086, respectively). IL-10 ATA single and double haplotypes were significantly higher in controls, compared to the patients (p= 0.0278 and p=0.013, respectively). CONCLUSION: According to the results higher frequency of C alleles at positions -592 and -819 of IL-10 in patients may be considered as genetic factors for susceptibility to brucellosis.

Association of interferon-gamma and interleukin-4 gene polymorphisms with susceptibility to brucellosis in Iranian patients.

Activation of macrophages and their antimicrobial activities by interferon-gamma (IFN-gamma) plays a crucial role in controlling Brucella infection. Interleukin-4 (IL-4) antagonizes the macrophage activity effects of IFN-gamma and thus inhibits cell-mediated immune reactions. Given that the production of IFN-gamma and IL-4 are under genetic control, we investigated the relationship between these two cytokine gene polymorphisms and the susceptibility to brucellosis. Hundred and ninety-five patients with brucellosis and 91 healthy animal husbandmen who owned infected animals and consumed their contaminated dairy products were selected to participate in this study. All individuals were genotyped for IFN-gamma and IL-4 gene polymorphisms at positions +874 and -590, respectively. Results showed that IFN-gammaAA genotype was significantly more prevalent (P =0.03) and IL-4CC genotype was significantly less frequent (P =0.034) in the patient group compared to the control group. Also, the frequency of IFN-gamma/IL-4 combination of genotype (IFN-gammaTT/IL-4CC) and allele (IFN-gammaT/IL-4C) were significantly higher in the controls than in the patients (P =0.033 and P =0.0035, respectively). Data suggest that individuals who have IFN-gammaAA genotype are more susceptible, and those who carry IL-4CC genotype are more resistant to brucellosis. We also suggest that individuals who carry IFN-gammaT/IL-4C or IFN-gammaTT/IL-4CC can be more resistant to Brucella infection.

Association study of IL-10 and IFN-gamma gene polymorphisms in Iranian women with preeclampsia.

Preeclampsia (PE) is one of the most serious disorders of human pregnancy and Th1/Th2 imbalance may play a role in its etiology. Considering that cytokine production is under genetic control, in this study we have investigated IFN-gamma+874 (T/A) and three bi-allelic IL-10 promoter polymorphisms in a total of 134 preeclamptic women compared to 164 healthy women. It was shown that the IL-10 -1082 G allele frequency increases significantly in patients compared to the control group (P=0.045). No significant differences were found in any other genotype or allele frequencies of IL-10 and IFN-gamma genes between the two groups. In addition, the frequencies of three common IL-10 haplotypes (GCC, ACC, ATA) did not show any significant difference between the study groups. Since the presence of G nucleotide at position -1082 of IL-10 gene is associated with reduced cytokine production, therefore, the higher frequency of IL-10 -1082 G allele in preeclamptic patients compared to controls may be considered as a genetic susceptibility factor for the development of PE.