Orally Bioavailable Small-Molecule CD73 Inhibitor (OP-5244) Reverses Immunosuppression through Blockade of Adenosine Production

The adenosinergic pathway represents an attractive new therapeutic approach in cancer immunotherapy. In this pathway, ecto-5-nucleotidase CD73 has the unique function of regulating production of immunosuppressive adenosine (ADO) through the hydrolysis of AMP. CD73 is overexpressed in many cancers, resulting in elevated levels of ADO that correspond to poor patient prognosis. Therefore, reducing the level of ADO via inhibition of CD73 is a potential strategy for treating cancers. Based on the binding mode of adenosine 5'-(α,β-methylene)diphosphate (AOPCP) with human CD73, we designed a series of novel monophosphonate small-molecule CD73 inhibitors. Among them, OP-5244 (35) proved to be a highly potent and orally bioavailable CD73 inhibitor. In preclinical studies, 35 completely inhibited ADO production in both human cancer cells and CD8⁺ T cells. Furthermore, 35 lowered the ratio of ADO/AMP significantly and reversed immunosuppression in mouse models, indicating its potential as an in vivo tool compound for further development.

Abstract LB-115: An orally bioavailable inhibitor of CD73 reverts intratumoral immunosuppression and promotes anti-tumor responses

The 5' ecto-nucleotidase CD73 is dynamically expressed in distinct biological contexts as a means to increase the adenosine metabolite, which functions to limit immune activation and prevent excessive inflammation. CD73 activity is required for the final step of adenosine production. In the context of tumors, excessive CD73-mediated adenosine generation impairs anti-tumor immune responses. Here, we show that an orally bioavailable small molecule inhibitor of CD73 can prevent adenosine generation, relieve adenosine-driven immunosuppression within the tumor in vivo and generate anti-tumor efficacy.

In vitro analysis confirmed the substantial suppressive effects of adenosine on murine CD8+ T cells, cross-presenting dendritic cells, and macrophages. NECA, a stable analog of adenosine, impaired immature bone-marrow precursor differentiation into CD103+ dendritic cells, a subset which is critical for tumor-derived antigen presentation to naïve T cells. Interestingly, NECA also inhibited the ability of macrophages to upregulate the M1 marker, CD80, in both the presence and absence of additional polarizing stimuli. Furthermore, OR-558, a CD73 small molecule inhibitor, could fully inhibit CD73-mediated adenosine production and completely restore T cell activation at sub-nanomolar concentrations.

Prior work in CD73 germline knock-out animals has shown that EG7 syngeneic tumor growth is highly dependent on CD73. Building on this knowledge, we next we sought to evaluate CD73 inhibition on AMP to adenosine conversion ex vivo in EG7 syngeneic tumor extracts and indeed observed that OR-558 treatment could significantly impair adenosine production within the tumor milieu. This finding translated to the in vivo tumor setting, where single agent anti-tumor efficacy was observed with continuous OR-558 treatment. Anti-tumor efficacy coincided with significantly decreased intra-tumoral adenosine levels and immune modulation, such as increased intratumoral T cell activation, dendritic cell maturation, and M1 macrophage polarization. Lastly, we determined the bioavailability of orally dosed OR-558 in EG7 tumor-bearing mice and found that significant single agent anti-tumor efficacy was also achievable with once-daily oral dosing of OR-558. Taken together, these data demonstrate that adenosine has pleiotropic immunosuppressive effects and inhibition of CD73-mediated adenosine production in vivo is sufficient to reverse these immune effects and enhance anti-tumor immunity. These results support clinical development of orally bioavailable CD73 small molecule inhibitors.

Citation Format: Todd Metzger, Brian Blank, Brenda Chan, Chelsea Chen, Yuping Chen, Xiaohui Du, Frank Duong, Lori Friedman, Melissa Junttila, Hiro Kawai, Wayne Kong, Jared Moore, Johnny Pham, Yosup Rew, Daqing Sun, Jessica Sun, Dena Sutimantanapi, Kejia Wu, Chien-Hung Yeh, Natalie Yuen, Tatiana Zavorotinskaya. An orally bioavailable inhibitor of CD73 reverts intratumoral immunosuppression and promotes anti-tumor responses [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-115.

Abstract 1037: Orally available small molecule CD73 inhibitor reverses immunosuppression through blocking of adenosine production

CD73 has emerged as an attractive target for cancer immunotherapy. CD73 (ecto-5-nucleotidase) is a glycosyl phosphatidyl inositol (GPI)-anchored cell surface protein and catalyzes the hydrolysis of AMP into immunosuppressive adenosine and inorganic phosphate. CD73 is widely overexpressed in tumor microenvironments (TME) of many cancers, resulting in elevated levels of extra cellular adenosine (ADO). ADO plays a critical role in tumor progression through immune suppression, chemotherapy resistance, metastasis and angiogenesis. Therefore, reducing the level of adenosine via inhibition of CD73 has become a potential strategy for treating cancers. Here we report our medicinal chemistry efforts in developing orally available small molecule CD73 inhibitors. Based on the binding mode of adenosine 5'-(α,β-methylene)diphosphate (APCP) with CD73, we designed a novel series of monophosphate CD73 inhibitors, which are highly potent and orally bioavailable. In preclinical studies, OP-5244 inhibited ADO production completely in human cancer cells and CD8+ T cells. It also showed dose-dependent inhibitory effects on CD73 activity in various tumors ex vivo. Furthermore, OP-5244 showed PK/PD efficacy through lowering of ADO/AMP ratio and reversal of immunosuppression in vivo.

Citation Format: Xiaohui Du, Brian Blank, Brenda Chan, Xi Chen, Yuping Chen, Frank Duong, Lori Friedman, Tom Huang, Melissa R. Junttila, Wayne Kong, Todd Metzger, Jared Moore, Daqing Sun, Jessica Sun, Dena Sutimantanapi, Natalie Yuen, Tatiana Zavorotinskaya. Orally available small molecule CD73 inhibitor reverses immunosuppression through blocking of adenosine production [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1037.

Abstract 1023: CD73 inhibition with a novel orally bioavailable small molecule blocks adenosine production and rescues T-cells activation

Adenosine has emerged as a key immunosuppressive metabolite within the tumor microenvironment (TME). A persistently elevated concentration of adenosine in TME can impair immune control of tumor growth by diminishing cytotoxic T-cell responses and function of natural killer cells while augmenting the suppressive activity of myeloid and regulatory T-cells. The ectonucleotidase, CD73 mediates the final dephosphorylation step in the conversion of extracellular ATP to adenosine. Overexpression of CD73 is observed in many solid tumors and correlates with unfavorable clinical outcome. We aimed to overcome adenosine-driven immunosuppression by developing an orally bioavailable, best-in-class, small molecule inhibitor of CD73. Here, we show superior potency of our selective AMP-competitive CD73 inhibitor in blocking adenosine generation by multiple cell types. CD73 inhibitor activity was assessed by directly measuring the generation of adenosine from AMP by LC-MS/MS. In CD73 expressing cells, potent and complete inhibition of CD73 ectonucleotidase activity was observed. To test the functional consequence of CD73 inhibition, we interrogated the effects of CD73 inhibitors on CD8+ T-cell function upon exposure to AMP. CD73 expressed on T-cells is sufficient to drive adenosine generation from AMP resulting in severely suppressed proliferation, diminished production of inflammatory cytokines and reduced expression of activation markers. Our inhibitors successfully counteracted the effects of AMP and completely rescued all aspects of CD8+ T-cell activation. Interestingly, we found that the concentration of AMP in tumors may vary from micromolar to millimolar levels, underscoring the necessity of AMP-competitive CD73 inhibitors to be efficacious in a high AMP environment. We demonstrated that nanomolar concentrations of our CD73 inhibitors can efficiently rescue T-cell function in the presence of millimolar AMP concentrations. We are currently conducting biophysical studies to better understand this unique property of our inhibitors. We next aimed to identify an adenosine responsive gene signature in cytotoxic T-cells. RNA sequencing analysis of primary anti-CD3/28/2 activated CD8+ T-cells from human peripheral blood mononuclear cells revealed a unique set of genes persistently and similarly altered in response to both adenosine and AMP. Finally, we demonstrated that CD73 inhibitors can completely block gene expression changes of this AMP/adenosine-response signature. Discovery of an AMP/adenosine-response gene signature may help identify patients whose tumors harbor elevated adenosine signaling and would benefit from an orally bioavailable small molecule inhibitor of CD73 to reverse immunosuppression.

Citation Format: Tatiana Zavorotinskaya, Brian Blank, Brenda Chan, Chelsea Chen, Yuping Chen, Xiaohui Du, Frank Duong, Lori Friedman, Tom Huang, Melissa R. Junttila, Wayne Kong, Todd C. Metzger, Jared T. Moore, Daqing Sun, Jessica Sun, Dena Sutimantanapi, Natalie Yuen. CD73 inhibition with a novel orally bioavailable small molecule blocks adenosine production and rescues T-cells activation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1023.

LncRNA SNHG12 accelerates the progression of ovarian cancer via absorbing miRNA-129 to upregulate SOX4

OBJECTIVE

To clarify whether long non-coding RNA (lncRNA) SNHG12 could regulate the proliferative and migratory abilities of ovarian cancer (OC) cells through mediating microRNA-129 (miRNA-129), thus influencing the progression of OC.

PATIENTS AND METHODS

The expression patterns of SNHG12 and miRNA-129 in OC tissues and adjacent normal tissues were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Meanwhile, their expression levels in OC cell lines were also examined. Regulatory effects of SNHG12 and miRNA-129 on the proliferative and migratory abilities of OC cells were evaluated by cell counting kit-8 (CCK-8) and transwell assay, respectively. Through the dual-luciferase reporter gene assay, we explored the binding between miRNA-129 with SNHG12 and SOX4. A series of rescue experiments were conducted to clarify the role of SNHG12/miRNA-129/SOX4 regulatory loop in the progression of OC.

RESULTS

SNHG12 was upregulated in OC tissues relative to adjacent normal ones. Patients with metastatic OC or those in stage III-IV had a higher level of SNHG12 compared with non-metastatic or stage I-II patients. The 5-year survival was markedly worse in OC patients with high-level SNHG12 than those in the low-level group. Similarly, SNHG12 was highly expressed in OC cell lines. Overexpression of SNHG12 accelerated A2780 and HO8910 cells to proliferate and migrate. We observed the binding between SNHG12 and miRNA-129, and the latter was lowly expressed in OC. The miRNA-129 overexpression partially reversed the promotive effects of SNHG12 on proliferative and migratory abilities of OC cells. Subsequently, SOX4 was proved to be the target gene of miRNA-129. The SOX4 overexpression was further confirmed to reverse the inhibitory effects of miRNA-129 on proliferative and migratory abilities of OC cells.

CONCLUSIONS

SNHG12 accelerates the proliferative and migratory abilities of OC cells via sponging miRNA-129 to upregulate SOX4.

Rapamycin repairs damaged nerve cells and neurological function in rats with spinal cord injury through ERK signaling pathway

The object of this study was to explore the effect of rapamycin regulating the proliferation of Schwann cells through activating the extracellular signal-regulated kinase (ERK) signaling pathway on rats with spinal cord injury (SCI). The rat Schwann cells were cultured and divided into solvent (DMSO) group, rapamycin (Rapa) group (1.5 nM, 3.0 nM, 6.0 nM, 12.0 nM, 24.0 nM and 48.0 nM), and Rapa + ERK inhibitor (PD98059) group (40 mM). The proliferation of Schwann cells was detected by MTS. Western blot was used to evaluate the expression of ERK and p-ERK protein. Moreover, the spinal cord compression injury rat model was established, and the rats were divided into normal control group, SCI group and Schwann cell transplantation group. The animal experiment ended 7 weeks after Schwann cells had been injected every day into the injured rats. In the second animal experiment, the rats were divided into DMSO group, Rapa group and Rapa + PD98059 group. The motor recovery of rats was evaluated using the Basso-Beattie-Bresnahan (BBB) score every week, and the proliferation of Schwann cells at the site of SCI was detected using immunohistochemistry. It was verified that lowdose rapamycin (1.5 nM) could significantly promote the proliferation of Schwann cells cultured in vitro (P<0.001), most significantly at 48 h. Rapamycin could activate the ERK signaling pathway. The results of the first animal experiment showed that the BBB score in Schwann cell transplantation group rose with time compared with that in SCI group (P<0.05). The BBB score was obviously increased in Rapa group compared with that in DMSO group and Rapa + PD98059 group (P<0.05). According to the results of Ki67 immunohistochemistry, the proliferation ability of Schwann cells at the site of SCI was remarkably stronger than that in the other two groups. Rapamycin regulates the proliferation of Schwann cells through the ERK signaling pathway. The proliferation of Schwann cells can effectively repair the damaged nerve cells and neurological function in SCI rats.

Cdc14a has a role in spermatogenesis, sperm maturation and male fertility

Cdc14a is an evolutionarily conserved dual-specific protein phosphatase, and it plays different roles in different organisms. Cdc14a mutations in human have been reported to cause male infertility, while the specific role of Cdc14a in regulation of the male reproductive system remains elusive. In the present study, we established a knockout mouse model to study the function of Cdc14a in male reproductive system. Cdc14a^-/- male mice were subfertile and they could only produce very few offspring. The number of sperm was decreased, the sperm motility was impaired, and the proportion of sperm with abnormal morphology was elevated in Cdc14a^-/- mice. When we mated Cdc14a^-/- male mice with wild-type (WT) female mice, fertilized eggs could be found in female fallopian tubes, however, the majority of these embryos died during development. Some empty spaces were observed in seminiferous tubule of Cdc14a^-/- testes. Compared with WT male mice, the proportions of pachytene spermatocytes were increased and germ cells stained with γH2ax were decreased in Cdc14a^-/- male mice, indicating that knockout of Cdc14a inhibited meiotic initiation. Subsequently, we analyzed the expression levels of some substrate proteins of Cdc14a, including Cdc25a, Wee1, and PR-Set7, and compared those with WT testes, in which the expression levels of these proteins were significantly increased in Cdc14a^-/- testes. Our results revealed that Cdc14a^-/- male mice are highly subfertile, and Cdc14a is essential for normal spermatogenesis and sperm function.

[Application of intestinal stent in prevention of anastomotic leakage after rectal cancer operation]

Objective: To observe preventive effect of intestinal stent against anastomotic leakage after rectal cancer operation. Methods: A retrospective cohort study was carried out. Clinical data of 107 patients with low rectal cancer undergoing laparoscopic radical resection from January 2015 to August 2019 were retrospectively analyzed. Intestinal stent was placed intraoperatively in 48 cases and was not placed in 59 cases. Postoperative Wexner score for anal function and incidence of anastomotic leakage were compared between patients with and without intstinal stent. Results: There was no significant differences in age, distance between tumor and the anal verge, operative time and postoperative Wexner score for anal function between the two groups (all P>0.05). After a month of follow-up, the incidence of anastomotic leakage was 16.9% (10/59) in the non-stent group, while no anastomotic leakage was found in the stent group (P=0.002). Conclusion: Placement of intestinal stent can effectively prevent anastomotic leakage after low rectal cancer surgery.

[Characteristics and clinical significance of pulmonary function test and KL-6 in ASSD-ILD and IPF]

Objective: To study the characteristics and clinical significance of pulmonary function test and kerbs von den lungen 6 (KL-6) in anti-synthetase syndrome related interstitial lung disease (ASSD-ILD) and idiopathic pulmonary fibrosis (IPF). Methods: The clinical data of 43 patients with ASSD-ILD (ASSD-ILD group) from May 2015 to May 2017 were collected retrospectively, including 12 males and 31 females, and 34 patients with IPF (IPF group) treated in the First Affiliated Hospital of Zhengzhou University during the same period, including 28 males and 6 females, were also included. The basic information, and the value of pulmonary function test [pulmonary function parameters included the forced vital capacity expressed as percent predicted (FVC%pred), the forced expiratory volume in 1 second expressed as percent predicted (FEV(1)%pred), the ratio of FVC to FEV(1) (FVC/FEV(1)), the peak expiratory flow expressed as percent predicted (PEF%pred), the forced expiratory flow at 25%, 50%, 75% of FVC as percent predicted (FEF(25)%pred, FEF(50)%pred, and FEF(75)%pred), the maximum mid-expiratory flow as percent predicted (MMEF% pred), and the diffusing capacity for carbon monoxide as percent predicted (DLCO% pred)], and serum KL-6 level in ASSD-ILD and IPF were compared. Results: The FEV(1)%pred, FEF(50)%pred, FEF(75)%pred, and MMEF%pred values in ASSD-ILD group were significantly lower than those in IPF group (all P<0.05), while the FVC% pred, FVC/FEV(1), PEF% pred, FEF(25)%pred, and DLCO% pred values in ASSD-ILD group had no significant difference compared with IPF group (all P>0.05). There was no significant difference in serum KL-6 level between ASSD-ILD group and IPF group [(1 169±911) vs (1 210±908) U/ml, t=0.62, P=0.463]. Follow-up analysis showed that the serum KL-6 level of ASSD-ILD patients who died within two years was significantly higher than that of survivors [(2 060±1 168) vs (1 042±858) U/ml, t=2.93, P=0.041]. The serum KL-6 level of patients who died within two years of IPF patients was also significantly higher than that of patients who survived [(1 767±865) vs (1 089±894) U/ml, t=2.53, P=0.026]. The serum KL-6 level in ASSD-ILD group was negatively correlated with FVC%pred (r=-0.43, P=0.004), FEV(1)%pred (r=-0.39, P=0.010) and DLCO% pred (r=-0.41, P=0.006). There was no correlation between serum KL-6 level and pulmonary function test indexes in IPF group (all P>0.05). Conclusions: There is difference in pulmonary function test between ASSD-ILD patients and IPF patients. High serum KL-6 level will be predictive of poor prognosis.

The analysis of dissolved inorganic carbon in liquid using a microfluidic conductivity sensor with membrane separation of CO2

Autonomous continuous analysis of oceanic dissolved inorganic carbon (DIC) concentration with depth is of great significance with regard to ocean acidification and climate change. However, miniaturisation of in situ analysis systems is hampered by the size, cost and power requirements of traditional optical instrumentation. Here, we report a low-cost microfluidic alternative based on CO₂ separation and conductance measurements that could lead to integrated lab-on-chip systems for ocean float deployment, or for moored or autonomous surface vehicle applications. Conductimetric determination of concentration, in the seawater range of 1000-3000 µmol kg^-1, has been achieved using a microfluidic thin-film electrode conductivity cell and a membrane-based gas exchange cell. Sample acidification released CO₂ through the membrane, reacting in a NaOH carrier, later drawn through a sub-µL conductivity cell, for impedance versus time measurements. Precision values (relative standard deviations) were ~ 0.2% for peak height measurements at 2000 µmol kg^-1. Comparable precision values of ~ 0.25% were obtained using a C4D electrophoresis headstage with similar measurement volume. The required total sample and reagent volumes were ~ 500 µL for the low volume planar membrane gas exchange cell. In contrast, previous conductivity-based DIC analysis systems required total volumes between 5000 and 10,000 µL. Long membrane tubes and macroscopic wire electrodes were avoided by incorporating a planar membrane (PDMS) in the gas exchange cell, and by sputter deposition of Ti/Au electrodes directly onto a thermoplastic (PMMA) manifold. Future performance improvements will address membrane chemical and mechanical stability, further volume reduction, and component integration into a single manifold.

Identification of genetic effects and potential causal polymorphisms of CPM gene impacting milk fatty acid traits in Chinese Holstein

Our previous GWAS revealed 83 significant SNPs and 20 promising candidate genes associated with milk fatty acid traits in dairy cattle. Out of them, the carboxypeptidase M (CPM) gene contains a genome-wide significant SNP, Hapmap49848-BTA-106779, which is strongly associated with myristic acid (C14:0; P = 0.0064). Herein, we aimed to confirm the genetic effects of CPM on milk fatty acids in Chinese Holstein. Seven SNPs were detected by re-sequencing the sequences of entire exons and 3000 bp of up-/downstream flanking regions of the CPM gene, of which three were in 5' flanking region, one in the 3' UTR and three were in the 3' flanking region. Using the Haploview 4.1, we estimated the LD among the identified SNPs and found two haplotype blocks. With the animal model, we performed the SNP- and haplotype-based association analyses, and observed that these SNPs and haplotype blocks mainly had strong genetic associations with medium-chain saturated fatty acids (caproic acid, C6:0; caprylic acid, C8:0; capric acid, C10:0; and lauric acid, C12:0) (P < 0.0001-0.0257). In addition, using the Genomatix software, we predicted that three SNPs in the 5' flanking region of CPM (g.45079507A>G, g.45080228C>A and g.45080335C>G) changed the transcription factor binding sites for PREF (progesterone receptor biding site), ZBRK1 (transcription factor with eight central zinc fingers and an N-terminal KRAB domain), SOX9 (sex-determining region Y-box 9, dimeric binding sites), SOX6 (sex-determining region Y-box 6) and FOXP1-ES (alternative splicing variant of FOXP1, activated in ESCs). Further, the dual-luciferase reporter assay showed these three SNPs altered the transcriptional activity of CPM gene (P ≤ 0.0006). In summary, using the post-GWAS strategy, we first confirmed the significant genetic effects of CPM with milk fatty acids in dairy cattle, and identified three potential causal mutations.

Detection of Hole Pockets in the Candidate Type-II Weyl Semimetal MoTe_{2} from Shubnikov-de Haas Quantum Oscillations

The bulk electronic structure of T_{d}-MoTe_{2} features large hole Fermi pockets at the Brillouin zone center (Γ) and two electron Fermi surfaces along the Γ-X direction. However, the large hole pockets, whose existence has important implications for the Weyl physics of T_{d}-MoTe_{2}, has never been conclusively detected in quantum oscillations. This raises doubt about the realizability of Majorana states in T_{d}-MoTe_{2}, because these exotic states rely on the existence of Weyl points, which originated from the same band structure predicted by density functional theory (DFT). Here, we report an unambiguous detection of these elusive hole pockets via Shubnikov-de Haas (SdH) quantum oscillations. At ambient pressure, the quantum oscillation frequencies for these pockets are 988 and 1513 T, when the magnetic field is applied along the c axis. The quasiparticle effective masses m^{*} associated with these frequencies are 1.50 and 2.77 m_{e}, respectively, indicating the importance of Coulomb interactions in this system. We further measure the SdH oscillations under pressure. At 13 kbar, we detected a peak at 1798 T with m^{*}=2.86m_{e}. Relative to the oscillation data at a lower pressure, the amplitude of this peak experienced an enhancement, which can be attributed to the reduced curvature of the hole pockets under pressure. Combining our experimental data with DFT+U calculations, where U is the Hubbard parameter, our results shed light on why these important hole pockets have not been detected until now.

[Clinical phenotypes of epilepsy associated with GABRA1 gene variants]

Objective: To summarize the clinical phenotypes of epilepsy in patients with GABRA1 gene variants. Methods: A total of 11 epileptic patients (4 boys and 7 girls) who were treated in the Department of Pediatrics, Peking University First Hospital from March 2016 to July 2019 and detected with GABRA1 gene heterozygous pathogenic variants by targeted next-generation sequencing were enrolled. The features of clinical manifestations, electroencephalogram (EEG), and neuroimaging were analyzed retrospectively. Results: A total of 11 epileptic patients carried GABRA1 gene pathogenic variants, of whom 10 were de novo variants and the other one was inherited from the patient's mother. Two patients had the same variants. Six variants were novel. Ages at seizure onset ranged from 3 to 14 months, and the median age was 8 months. The seizure was first observed within 1 year in 10 patients and beyond 1 year of age in 1 patient. Multiple seizure types were observed, including focal seizures in 10 patients, generalized tonic clonic seizures (GTCS) in 3 patients, myoclonic seizures in 3 patients, and epileptic spasm in 2 patients. There were 5 patients with multiple seizure types. Sensitivity to fever was observed in 9 patients, among whom 6 patients had a history of status epilepticus. Two patients had photoparoxysmal response. Five patients had abnormal EEG background, and 6 patients had abnormal discharges in EEG during interictal phase. Brain magnetic resonance imaging (MRI) was normal in all patients. Developmental delay in various degrees was present in 9 patients. Among the 11 patients, Dravet syndrome was diagnosed in 5 patients, West syndrome in 2 patients, undiagnosed early-onset epileptic encephalopathy in 1 patient, and focal epilepsy in the other 3 patients. The ages at the last follow-up ranged from 8 months to 12 years. During follow-up, 8 patients were seizure-free for 6 months to 8 years, and 1 patient had discontinuation of medication. Conclusions: In epilepsy associated with GABRA1 gene variants, de novo pathogenic variants are more common than inherited. Most epilepsy caused by GABRA1 gene variants occurs in infancy. Most patients have multiple seizures and focal seizures are common. Most patients have a comparatively favorable prognosis, but they may still have varied degrees of developmental delay.

Precise annotation of human, chimpanzee, rhesus macaque and mouse mitochondrial genomes leads to insight into mitochondrial transcription in mammals

In the present study, we applied our 'precise annotation' to the mitochondrial (mt) genomes of human, chimpanzee, rhesus macaque and mouse using 5' and 3' end small RNAs. Our new annotations updated previous annotations. In particular, our new annotations led to two important novel findings: (1) the identification of five Conserved Sequence Blocks (CSB1, CSB2, CSB3, LSP and HSP) in the control regions; and (2) the annotation of Transcription Initiation and novel Transcription Termination Sites. Based on these annotations, we proposed a novel model of mt transcription which can account for the mt transcription and its regulation in mammals. According to our model, Transcription Termination Sites function as switches to regulate the production of short, long primary transcripts and uninterrupted transcription, rather than simply terminate the mt transcription. Moreover, the expression levels of mitochondrial transcription termination factors control the proportions of rRNAs, mRNAs and lncRNAs in total mt RNA. Our findings point to the existence of many other, as yet unidentified, Transcription Termination Sites in mammals.

Abstract LB-A19: Intratumoral immunosuppression is reversed by blocking adenosine production with an oral inhibitor of CD73

Introduction: CD73 mediates the final dephosphorylation in the conversion of extracellular ATP to adenosine, a metabolite which signals through the A2 family of receptors. Like PD-1, adenosine appears to be part of a negative feedback loop to limit immune activation and prevent excessive inflammation in the context of tissue damage. However, intratumoral hypoxia likely drives excessive CD73-mediated adenosine generation and prevents optimal anti-tumor immune responses. We show that intratumoral adenosine levels are sufficient to drive pervasive suppression of multiple immune subsets in vitro and an orally bioavailable small molecule can prevent adenosine generation in vitro and within the tumor in vivo. Methods We examined the effects of adenosine signaling on multiple immune cell subsets through in vitro functional assays. We interrogated T cell activation, proliferation, and cytolytic activity, as well as NK cell function in vitro. Furthermore, we investigated and identified functional targets of adenosine signaling within T cells using transcriptomic and protein expression analyses. In addition, we performed in vitro myeloid differentiation assays to determine the effect of adenosine signaling on myeloid lineage maturation. Finally, we explored the activity of a novel, orally bioavailable inhibitor of CD73 in vitro and assessed its ability to rescue T cell activation and suppress AMP conversion to adenosine within the tumor microenvironment. Results and Conclusions We found that T cell-expressed CD73 was sufficient to drive adenosine generation from AMP in vitro, resulting in suppression of anti-CD3/CD28-induced T cell activation and proliferation and a reduced capacity to kill cognate antigen-expressing tumor cells. Adenosine-exposed T cells displayed decreased induction of markers associated with activation at both the mRNA and protein level, including Ki67, ICOS, and PD-1, while showing higher expression of naïve-associated CD73. Interestingly, we also observed a third subset of markers which were uniquely induced by adenosine. In addition to its activity on T cells, adenosine signaling caused functional suppression of NK cells in the presence of target Yac-1 cells. In the myeloid compartment, NECA, a stable analog of adenosine, prevented in vitro differentiation of CD103+ cross-presenting dendritic cells, a population which provides a critical stimulus to tumor-infiltrating T cells. Additionally, NECA impaired macrophage expression of CD80, a canonical M1 marker and mediator of T cell costimulation, in both the presence and absence of M1-polarizing IFNγ and LPS. Finally, we showed that a novel, orally bioavailable CD73 inhibitor was able to effectively inhibit AMP to adenosine conversion both in vitro and in vivo, while an anti-CD73 antibody had incomplete effects. Taken together, an orally bioavailable small molecule inhibitor of CD73 represents a potential therapeutic approach to reverse immunosuppression within the tumor microenvironment.

Citation Format: Todd C Metzger, Brian R Blank, Brenda Chan, Chelsea Chen, Yuping Chen, Xiaohui Du, Frank L Duong, Valeria R. Fantin, Lori S Friedman, Jared T Moore, Daqing Sun, Jessica Sun, Dena Sutimantanapi, Qiuping Ye, Natalie Yuen, Tatiana Zavorotinskaya. Intratumoral immunosuppression is reversed by blocking adenosine production with an oral inhibitor of CD73 [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr LB-A19. doi:10.1158/1535-7163.TARG-19-LB-A19

Retirement planning: the perceptions of pre-retirement nurses within different hospitals in China

AIM

This study explored the perceptions of senior Chinese nurses working in different hospital types, about retirement planning; and compared the results from two hospitals.

BACKGROUND

A recent review indicates that nurses with inadequate retirement planning could be faced with a retirement crisis. In China, hospitals are classified into different levels, and salaries, job satisfaction and the turnover of nurses varies among these levels. These factors may also influence nurses' perceptions of retirement planning.

METHODS

In a descriptive, qualitative design, 27 semi-structured individual interviews were conducted with nurses who were between 50 and 60 years old and recruited from two hospitals in China from April to September 2018. The interviews were transcribed and analysed thematically.

FINDINGS

Four main themes emerged from the interviews, namely, the understanding of pre-retirement nurses of retirement planning, the attitudes of pre-retirement nurses towards retirement planning, factors influencing nurses' retirement planning and the retirement planning activity of nurses. Most nurses participating in this study did not know much about retirement planning, but they all agreed on its importance. We identified the influencing factors of retirement planning and several differences regarding the perceptions of nurses about retirement planning in different hospitals.

CONCLUSION

In this cohort of nurses, planning for a good retirement was thought to be important; however, their readiness for retirement and the influences around planning for retirement were varied in type and scope.

IMPLICATIONS FOR POLICY

Governments and employing hospitals should develop reasonable measures and policies to support nurses in their understanding of the benefits of retirement planning and help them to prepare for retirement. Information about retirement planning should be made available and options for planning explained. Any systematic hurdles to retirement planning should be mitigated or eliminated.

Combining multi-population datasets for joint genome-wide association and meta-analyses: The case of bovine milk fat composition traits

In genome-wide association studies (GWAS), sample size is the most important factor affecting statistical power that is under control of the investigator, posing a major challenge in understanding the genetics underlying difficult-to-measure traits. Combining data sets available from different populations for joint or meta-analysis is a promising alternative to increasing sample sizes available for GWAS. Simulation studies indicate statistical advantages from combining raw data or GWAS summaries in enhancing quantitative trait loci (QTL) detection power. However, the complexity of genetics underlying most quantitative traits, which itself is not fully understood, is difficult to fully capture in simulated data sets. In this study, population-specific and combined-population GWAS as well as a meta-analysis of the population-specific GWAS summaries were carried out with the objective of assessing the advantages and challenges of different data-combining strategies in enhancing detection power of GWAS using milk fatty acid (FA) traits as examples. Gas chromatography (GC) quantified milk FA samples and high-density (HD) genotypes were available from 1,566 Dutch, 614 Danish, and 700 Chinese Holstein Friesian cows. Using the joint GWAS, 28 additional genomic regions were detected, with significant associations to at least 1 FA, compared with the population-specific analyses. Some of these additional regions were also detected using the implemented meta-analysis. Furthermore, using the frequently reported variants of the diacylglycerol acyltransferase 1 (DGAT1) and stearoyl-CoA desaturase (SCD1) genes, we show that significant associations were established with more FA traits in the joint GWAS than the remaining scenarios. However, there were few regions detected in the population-specific analyses that were not detected using the joint GWAS or the meta-analyses. Our results show that combining multi-population data set can be a powerful tool to enhance detection power in GWAS for seldom-recorded traits. Detection of a higher number of regions using the meta-analysis, compared with any of the population-specific analyses also emphasizes the utility of these methods in the absence of raw multi-population data sets to undertake joint GWAS.

Identification of genetic associations of ECHS1 gene with milk fatty acid traits in dairy cattle

Our previous genome-wide association study identified 83 genome-wide significant SNPs and 20 novel promising candidate genes for milk fatty acids in Chinese Holstein. Among them, the enoyl-CoA hydratase, short chain 1 (ECHS1) and enoyl-CoA hydratase and 3-hydroxyacyl CoA dehydrogenase (EHHADH) genes were located near two SNPs and one SNP respectively, and they play important roles in fatty acid metabolism pathways. We herein validated whether the two genes have genetic effects on milk fatty acid traits in dairy cattle. By re-sequencing the full-length coding region, partially adjacent introns and 3000 bp up/downstream flanking sequences, we identified 12 SNPs in ECHS1: two in exons, four in the 3' flanking region and six in introns. The g.25858322C>T SNP results in an amino acid replacement from leucine to phenylalanine and changes the secondary structure of the ECHS1 protein, and single-locus association analysis showed that it was significantly associated with three milk fatty acids (P = 0.0002-0.0013). The remaining 11 SNPs were found to be significantly associated with at least one milk fatty acid (P = <0.0001-0.0040). Also, we found that two haplotype blocks, consisting of nine and two SNPs respectively, were significantly associated with eight milk fatty acids (P = <0.0001-0.0125). However, none of polymorphisms was observed in the EHHADH gene. In conclusion, our findings are the first to indicate that the ECHS1 gene has a significant genetic impact on long-chain unsaturated and medium-chain saturated fatty acid traits in dairy cattle, although the biological mechanism is still undetermined and requires further in-depth validation.