A novel targeting signal for proximal clustering of the Kv2.1 K+ channel in hippocampal neurons

The discrete localization of ion channels is a critical determinant of neuronal excitability. We show here that the dendritic K+ channels Kv2.1 and Kv2.2 were differentially targeted in cultured hippocampal neurons. Kv2.1 was found in high-density clusters on the soma and proximal dendrites, while Kv2.2 was uniformly distributed throughout the soma and dendrites. Chimeras revealed a proximal restriction and clustering domain on the cytoplasmic tail of Kv2.1. Truncations and internal deletions revealed a 26-amino acid targeting signal within which four residues were critical for localization. This signal is not related to other known sequences for neuronal and epithelial membrane protein targeting and represents a novel cytoplasmic signal responsible for proximal restriction and clustering.

Janus kinase 3-activating mutations identified in natural killer/T-cell lymphoma

The molecular pathogenesis of natural killer/T-cell lymphoma (NKTCL) is not well understood. We conducted whole-exome sequencing and identified Janus kinase 3 (JAK3) somatic-activating mutations (A572V and A573V) in 2 of 4 patients with NKTCLs. Further validation of the prevalence of JAK3 mutations was determined by Sanger sequencing and high-resolution melt (HRM) analysis in an additional 61 cases. In total, 23 of 65 (35.4%) cases harbored JAK3 mutations. Functional characterization of the JAK3 mutations support its involvement in cytokine-independent JAK/STAT constitutive activation leading to increased cell growth. Moreover, treatment of both JAK3-mutant and wild-type NKTCL cell lines with a novel pan-JAK inhibitor, CP-690550, resulted in dose-dependent reduction of phosphorylated STAT5, reduced cell viability, and increased apoptosis. Hence, targeting the deregulated JAK/STAT pathway could be a promising therapy for patients with NKTCLs.

SIGNIFICANCE

Gene mutations causing NKTCL have not been fully identified. Through exome sequencing, we identified activating mutations of JAK3 that may play a significant role in the pathogenesis of NKTCLs. Our findings have important implications for the management of patients with NKTCLs.

Preparation and evaluation of the in vitro drug release properties and mucoadhesion of novel microspheres of hyaluronic acid and chitosan

Rapid mucociliary clearance of intranasally administered drugs is often a key factor in determining the bioavailability of such therapeutic agents. The use of mucoadhesive microparticles provide a potential strategy for improving retention of drugs within the nasal cavity, and thereby improve the resultant pharmacokinetic profile. This study describes the comparison of a number of novel, potentially mucoadhesive microspheres, prepared by solvent evaporation, composed of hyaluronic acid (HA), chitosan glutamate (CH) and a combination of the two with microcapsules of HA and gelatin prepared by complex coacervation. The microspheres had a mean particle size of 19.91+/-1.57 microm (HA), 28.60+/-1.34 microm (HA/CH), 29.47+/-3.58 microm (CH). The incorporation of a model drug, gentamicin sulphate (%) was 46.90+/-0.53 (HA), 28.04+/-1.21 (HA/CH) and 13.32+/-1.04 (CH). The in vitro release profiles of microsphere formulations prepared by solvent evaporation were determined. The release of gentamicin from HA and HA/CH was 50% longer than CH and was best modelled as a release from a matrix. The degree of mucoadhesion of each formulation was investigated by determining the mucociliary transport rate (MTR) of the microparticles across an isolated frog palate. Acacia/gelatin microcapsules were used as a positive control. The rank order of mucoadhesion for the microspheres and the microparticles was HA=HA/CH>CH>HA/gelatin>CHins. The entrapment of gentamicin did not affect the mucoadhesive properties (P>0.05, Mann--Whitney U-test). The combination of HA with chitosan may afford additional advantages in combining the mucoadhesive potential of HA with the penetration enhancing effect of chitosan.

Coadministration of angiopoietin-1 and vascular endothelial growth factor enhances collateral vascularization

Using growth factors to induce vasculogenesis is a promising approach in the treatment of ischemic legs and myocardium. Because the vasculogenesis requires a cascade of growth factors, their receptors, and intracellular signals, such therapies may require the application of more than a single growth factor. We examined the effect of 2 endothelial cell-specific growth factors, angiopoietin-1 (Ang1) and vascular endothelial growth factor (VEGF), on primary cultured porcine coronary artery endothelial cells. VEGF, but not Ang1, increased DNA synthesis and cell number. Ang1 or VEGF induced migration and sprouting activity, increased plasmin and matrix metalloproteinase-2 secretion, and decreased tissue inhibitors of metalloproteinase type 2 secretion. A combination of the submaximal doses of Ang1 and VEGF enhanced these effects and was more potent than the maximal dose of either alone. In a rabbit ischemic hindlimb model, a combination of Ang1 and VEGF gene delivery produced an enhanced effect on resting and maximal blood flow and capillary formation that was greater than that of either factor alone. Angiographic analyses revealed that larger blood vessels were formed after gene delivery of Ang1 or Ang1 plus VEGF than after VEGF gene delivery. These results suggest that combined treatment of Ang1 and VEGF could be used to produce therapeutic vascularization.

Syndecan-4 proteoglycan cytoplasmic domain and phosphatidylinositol 4,5-bisphosphate coordinately regulate protein kinase C activity

Phosphatidylinositol 4,5-bisphosphate (PIP2) is involved in the organization of the actin cytoskeleton by regulating actin-associated proteins. The transmembrane heparan sulfate proteoglycan syndecan-4 also plays a critical role in protein kinase C (PKC) signaling in the formation of focal adhesions and actin stress fibers. The cytoplasmic domain of syndecan-4 core protein directly interacts with and potentiates PKCalpha activity, and it can directly interact with the phos- phoinositide PIP2. We, therefore, investigated whether the interaction of inositol phosphates and inositol phospholipids with syndecan-4 could regulate PKC activity. Data from in vitro kinase assays using purified PKCalpha beta gamma show that in the absence of phosphatidylserine and diolein, PIP2 increased the extent of autophosphorylation of PKCalpha beta gamma and partially activated it to phosphorylate both histone III-S and an epidermal growth factor receptor peptide. This activity was dose-dependent, and its calcium dependence varied with PKC isotype/source. Addition of the cytoplasmic syndecan-4 peptide, but not equivalent syndecan-1 or syndecan-2 peptides, potentiated the partial activation of PKCalpha beta gamma by PIP2, resulting in activity greater than that observed with phosphatidylserine, diolein, and calcium. This study indicates that syndecan-4 cytoplasmic domain may bind both PIP2 and PKCalpha, localize them to forming focal adhesions, and potentiate PKCalpha activity there.

Structural characterization of beta-D-(1 --> 3, 1 --> 6)-linked glucans using NMR spectroscopy

Nondestructive structural analysis of a series of beta-D-(1 --> 3, 1 --> 6)-linked glucans (laminaran, curdlan, yeast glucan, scleroglucan, etc.) was performed using two-dimensional NMR spectroscopy. The relative ratios of H-1 at different AGUs provided the information about DPn and DB. The alpha-, and beta-anomeric protons on reducing terminals were assigned at 5.02 to approximately 5.03 ppm (J 3.6 to approximately 3.7 Hz), and 4.42 to approximately 4.43 ppm (J 7.6 to approximately 7.9 Hz), respectively, whereas the H-1 protons of internal AGUs and beta-(1 --> 6)-branched AGUs appeared at 4.56 to approximately 4.59 ppm (J 7.6 to approximately 7.8 Hz), and 4.26 to approximately 4.28 ppm (J 7.6 to approximately 10.6 Hz), respectively, in a mixed solvent of 6:1 Me2SO-d6-D2O at 80 degrees C. In the solvent, the OH peaks were eliminated from the spectra allowing the H-1 protons to appear clearly. In addition, the nonreducing terminal H-1 and H-1 at the AGU next to reducing terminal could be assigned at 4.45 to approximately 4.46 ppm (J 7.8 to approximately 7.9 Hz), and 4.51 to approximately 4.53 ppm (J 7.8 Hz), respectively. The DPn of the laminaran was 33 (polydispersity 1.12) and the DB was 0.07. The number of glucosyl units in the side chain of laminaran is more than one. The DPn and DB of the water-insoluble yeast glucan were 228 and 0.003, respectively. However the DPn of water soluble yeast glucan phosphate and curdlan was changed upon the number of freeze-drying processes and the content of water in the mixed solvent, respectively. And the DB of those were calculated as 0.02 and 0, respectively. The DB of scleroglucan was precisely calculated as 0.33, compared with the previously reported data. The H-1s at different AGUs of the various beta-D-(1 --> 3, 1 --> 6)-linked glucans having different DB can be exactly assigned by their chemical shifts in the mixed solvent system. This NMR analysis can be effectively used to determine the DP and DB of polysaccharides in a simple and non-destructive manner.

AIDS-Related Burkitt's Lymphoma Versus Diffuse Large-Cell Lymphoma in the Pre–Highly Active Antiretroviral Therapy (HAART) and HAART Eras: Significant Differences in Survival With Standard Chemotherapy

Purpose

To compare outcomes of patients with HIV-Burkitt's lymphoma (HIV-BL) and HIV-diffuse large-cell lymphoma (HIV-DLCL) after treatment with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) or M-BACOD (methotrexate, bleomycin, cyclophosphamide, etoposide) in pre–highly active antiretroviral therapy (HAART) versus HAART eras.

Patients and Methods

Three hundred sixty-three patients with AIDS-related lymphoma diagnosed from 1982 to 2003 were reviewed retrospectively, including 262 in the pre-HAART (HIV-BL, 117; HIV-DLCL, 145) and 101 in the HAART era (HIV-BL, 18; HIV-DLCL, 83). Pre-HAART included those who did not receive HAART, and HAART era included those diagnosed after January 1997 who received HAART.

Results

There were no significant differences between groups in terms of age, sex, history of injection drug use, prior AIDS, lactate dehydrogenase level, and disease stage at diagnosis. Compared with HIV-BL, HIV-DLCL was associated with significantly lower CD4 counts in the pre-HAART but not the HAART era. Although the overall median survival was similar for both groups in the pre-HAART era (HIV-BL, 6.4 months v HIV-DLCL, 8.3 months; P = .43), survival was significantly worse in patients with HIV-BL in the HAART era (HIV-BL, 5.7 months v HIV-DLCL, 43.2 months; P = .0003). Failure to attain complete remission and CD4 count less than 100 cells/mm3 independently predicted for poor survival in the pre-HAART era. In comparison, histology of HIV-BL and no attainment of complete remission were independent poor prognostic factors in the HAART era.

Conclusion

Survival of patients with HIV-DLCL has improved in the HAART era, along with CD4 count, whereas survival of similarly treated patients with HIV-BL remained poor. The current practice of using the same regimen for both groups of patients should be re-evaluated.

Antisense oligonucleotide-mediated MDM4 exon 6 skipping impairs tumor growth

MDM4 is a promising target for cancer therapy, as it is undetectable in most normal adult tissues but often upregulated in cancer cells to dampen p53 tumor-suppressor function. The mechanisms that underlie MDM4 upregulation in cancer cells are largely unknown. Here, we have shown that this key oncogenic event mainly depends on a specific alternative splicing switch. We determined that while a nonsense-mediated, decay-targeted isoform of MDM4 (MDM4-S) is produced in normal adult tissues as a result of exon 6 skipping, enhanced exon 6 inclusion leads to expression of full-length MDM4 in a large number of human cancers. Although this alternative splicing event is likely regulated by multiple splicing factors, we identified the SRSF3 oncoprotein as a key enhancer of exon 6 inclusion. In multiple human melanoma cell lines and in melanoma patient-derived xenograft (PDX) mouse models, antisense oligonucleotide-mediated (ASO-mediated) skipping of exon 6 decreased MDM4 abundance, inhibited melanoma growth, and enhanced sensitivity to MAPK-targeting therapeutics. Additionally, ASO-based MDM4 targeting reduced diffuse large B cell lymphoma PDX growth. As full-length MDM4 is enhanced in multiple human tumors, our data indicate that this strategy is applicable to a wide range of tumor types. We conclude that enhanced MDM4 exon 6 inclusion is a common oncogenic event and has potential as a clinically compatible therapeutic target.

Romidepsin Plus CHOP Versus CHOP in Patients With Previously Untreated Peripheral T-Cell Lymphoma: Results of the Ro-CHOP Phase III Study (Conducted by LYSA)

PURPOSE

Romidepsin, a histone deacetylase inhibitor, has demonstrated activity in relapsed or refractory peripheral T-cell lymphoma (PTCL) as a single agent. Cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) therapy is widely used as first-line treatment of PTCL; however, it has limited efficacy. Results from a phase Ib and II study showed the feasibility of combining romidepsin with CHOP (Ro-CHOP).

METHODS

This study is a randomized phase III study of Ro-CHOP versus CHOP in adult patients with previously untreated PTCL. All patients received CHOP in 3-week cycles for six cycles. Romidepsin, 12 mg/m2, was administered intravenously over a 4-hour period on days 1 and 8 of each 3-week cycle for six cycles. The primary end point was progression-free survival (PFS) according to International Working Group 1999 criteria.

RESULTS

Between January 2013 and December 2017, 421 patients were enrolled (Ro-CHOP, n = 211; CHOP, n = 210). The median PFS for Ro-CHOP versus CHOP was 12.0 months (95% CI, 9.0 to 25.8) versus 10.2 months (95% CI, 7.4 to 13.2) with a hazard ratio of 0.81 (P = .096). In the Ro-CHOP versus CHOP arms, the median overall survival was 51.8 versus 42.9 months and the objective response rate was 63% versus 60% with complete response plus unconfirmed complete response rates of 41% versus 37% (P > .1 in all comparisons), respectively. Grade 3 or 4 treatment-emergent adverse events occurring in ≥ 30% of patients in the Ro-CHOP arm included thrombocytopenia (50% v 10% in the Ro-CHOP v CHOP arms, respectively), neutropenia (49% v 33%), anemia (47% v 17%), and leukopenia (32% v 20%).

CONCLUSION

The addition of romidepsin to CHOP did not improve PFS, response rates, nor overall survival and increased the frequency for grade ≥ 3 treatment-emergent adverse events. Ro-CHOP does not represent a significant advance in the standard of care for patients with previously untreated PTCL.

Simultaneous Inhibition of PI3Kδ and PI3Kα Induces ABC-DLBCL Regression by Blocking BCR-Dependent and -Independent Activation of NF-κB and AKT

Compared with follicular lymphoma, high PI3Kα expression was more prevalent in diffuse large B cell lymphoma (DLBCL), although both tumor types expressed substantial PI3Kδ. Simultaneous inhibition of PI3Kα and PI3Kδ dramatically enhanced the anti-tumor profile in ABC-DLBCL models compared with selective inhibition of PI3Kδ, PI3Kα, or BTK. The anti-tumor activity was associated with suppression of p-AKT and a mechanism of blocking nuclear factor-κB activation driven by CD79^mut, CARD11^mut, TNFAIP3^mut, or MYD88^mut. Inhibition of PI3Kα/δ resulted in tumor regression in an ibrutinib-resistant CD79B^WT/MYD88^mut patient-derived ABC-DLBCL model. Furthermore, rebound activation of BTK and AKT was identified as a mechanism limiting CD79B^mut-ABC-DLBCL to show a robust response to PI3K and BTK inhibitor monotherapies. A combination of ibrutinib with the PI3Kα/δ inhibitor copanlisib produced a sustained complete response in vivo in CD79B^mut/MYD88^mut ABC-DLBCL models.

JAK-STAT and G-protein-coupled receptor signaling pathways are frequently altered in epitheliotropic intestinal T-cell lymphoma

Epitheliotropic intestinal T-cell lymphoma (EITL, also known as type II enteropathy-associated T-cell lymphoma) is an aggressive intestinal disease with poor prognosis and its molecular alterations have not been comprehensively characterized. We aimed to identify actionable easy-to-screen alterations that would allow better diagnostics and/or treatment of this deadly disease. By performing whole-exome sequencing of four EITL tumor-normal pairs, followed by amplicon deep sequencing of 42 tumor samples, frequent alterations of the JAK-STAT and G-protein-coupled receptor (GPCR) signaling pathways were discovered in a large portion of samples. Specifically, STAT5B was mutated in a remarkable 63% of cases, JAK3 in 35% and GNAI2 in 24%, with the majority occurring at known activating hotspots in key functional domains. Moreover, STAT5B locus carried copy-neutral loss of heterozygosity resulting in the duplication of the mutant copy, suggesting the importance of mutant STAT5B dosage for the development of EITL. Dysregulation of the JAK-STAT and GPCR pathways was also supported by gene expression profiling and further verified in patient tumor samples. In vitro overexpression of GNAI2 mutants led to the upregulation of pERK1/2, a member of MEK-ERK pathway. Notably, inhibitors of both JAK-STAT and MEK-ERK pathways effectively reduced viability of patient-derived primary EITL cells, indicating potential therapeutic strategies for this neoplasm with no effective treatment currently available.

Reproducing the molecular subclassification of peripheral T-cell lymphoma-NOS by immunohistochemistry

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of mature T-cell malignancies; approximately one-third of cases are designated as PTCL-not otherwise specified (PTCL-NOS). Using gene-expression profiling (GEP), we have previously defined 2 major molecular subtypes of PTCL-NOS, PTCL-GATA3 and PTCL-TBX21, which have distinct biological differences in oncogenic pathways and prognosis. In the current study, we generated an immunohistochemistry (IHC) algorithm to identify the 2 subtypes in paraffin tissue using antibodies to key transcriptional factors (GATA3 and TBX21) and their target proteins (CCR4 and CXCR3). In a training cohort of 49 cases of PTCL-NOS with corresponding GEP data, the 2 subtypes identified by the IHC algorithm matched the GEP results with high sensitivity (85%) and showed a significant difference in overall survival (OS) (P = .03). The IHC algorithm classification showed high interobserver reproducibility among pathologists and was validated in a second PTCL-NOS cohort (n = 124), where a significant difference in OS between the PTCL-GATA3 and PTCL-TBX21 subtypes was confirmed (P = .003). In multivariate analysis, a high International Prognostic Index score (3-5) and the PTCL-GATA3 subtype identified by IHC were independent adverse predictors of OS (P = .0015). Additionally, the 2 IHC-defined subtypes were significantly associated with distinct morphological features (P < .001), and there was a significant enrichment of an activated CD8+ cytotoxic phenotype in the PTCL-TBX21 subtype (P = .03). The IHC algorithm will aid in identifying the 2 subtypes in clinical practice, which will aid the future clinical management of patients and facilitate risk stratification in clinical trials.

Total parenteral nutrition versus gastrostomy in the preoperative preparation of patients with carcinoma of the oesophagus

Gastrostomy feeding has been a well established form of nutritional support for patients presenting with total dysphagia for carcinoma of the oesophagus. More recently, total parenteral nutrition has proved to be efficient and safe, offering an alternative to gastrostomy feeding. Twenty-four patients were randomly selected into two groups to compare the efficacy of total parenteral nutrition and gastrostomy feeding with respect to nitrogen balance and weight gain. Total parenteral nutrition was found to be superior to gastrostomy feeding in achieving an earlier positive nitrogen balance and greater weight gain during a 4-week period. However, gastrostomy feeding is still preferred as it is cheap, simple and safe, and allows patients to be active, mobile and self dependent. Total parenteral nutrition is reserved for those patients in whom an earlier operation is advisable.

Dynamic localization and clustering of dendritic Kv2.1 voltage-dependent potassium channels in developing hippocampal neurons

Dendritic excitability is modulated by the highly variable spatial and temporal expression pattern of voltage-dependent potassium channels. Somatodendritic Kv2.1 channels contribute a major component of delayed rectifier potassium current in cultured hippocampal neurons, where Kv2.1 is localized to large clusters on the soma and proximal dendrites. Here we found that dramatic differences exist in the clustering of endogenous Kv2.1 in cultured rat hippocampal GABAergic interneurons and glutamatergic pyramidal neurons. Studies on neurons developing in culture revealed that while a similar sequence of Kv2.1 localization and clustering occurred in both cell types, the process was temporally delayed in pyramidal cells. Localization and clustering of recombinant green fluorescent protein-tagged Kv2.1 occurred by the same sequence of events, and imaging of GFP-Kv2.1 clustering in living neurons revealed dynamic fusion events that underlie cluster formation. Overexpression of GFP-Kv2.1 accelerated the clustering program in pyramidal neurons such that the observed differences in Kv2.1 clustering in pyramidal neurons and interneurons were eliminated. Confocal imaging showed a preferential association of Kv2.1 with the basal membrane in cultured neurons, and electrophysiological recordings from neurons cultured on transistors revealed that Kv2.1 contributed the bulk of a previously described adherens junction delayed rectifier potassium conductance. Finally, Kv2.1 clusters were found spatially associated with ryanodine receptor intracellular Ca(2+) ([Ca(2+)](i)) release channels. These findings reveal a stepwise assembly of Kv2.1 potassium channels into membrane clusters during development, and an association of these clusters with Ca(2+) signaling apparatus. Together these data suggest that the restricted localization of Kv2.1 may play an important role in the previously observed contribution of this potassium channel in regulating dendritic [Ca(2+)](i) transients.

High SUV uptake on FDG-PET/CT predicts for an aggressive B-cell lymphoma in a prospective study of primary FDG-PET/CT staging in lymphoma

BACKGROUND

Data assessing the role of positron emission tomography (PET)/computed tomography (CT) imaging in lymphoma staging is still being accumulated and current staging is based primarily on CT. This study aims to compare the value of PET/CT over conventional CT and bone marrow biopsy (BMB) in the initial evaluation of patients with lymphoma.

METHODS

Data on 122 patients with PET/CT scans as part of their initial staging were prospectively collected and reviewed. All patients had complete staging, including BMB.

RESULTS

Among the 122 patients, 101 had non-Hodgkin's lymphoma (NHL) and 21 had Hodgkin's lymphoma (HL). Compared with conventional CT, PET/CT upstaged 21 (17%) cases [B-cell non-Hodgkin's lymphoma (B-NHL), 12; T-cell non-Hodgkin's lymphoma (T-NHL), 3; HL, 6]. Of significance, in 13 patients with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG)-avid splenic lesions, four had normal CT findings. A maximum FDG uptake of >10 standardized uptake value (SUV) seems to significantly correlate with an aggressive B-cell lineage (odds ratio 2.47, 95% confidence interval 2.23-2.70). Overall, PET scan was concordant with BMB results in 108 (89%) and discordant in 14 (11%) cases. In HL, our data show that PET scan and marrow results agreed in 19 of the cases (90%), being concordantly negative in 18 cases and concordantly positive in one, giving a negative predictive value (NPV) of 100%, sensitivity of 100% and specificity of 90%. Of note, all 13 with early-stage HL had negative PET/CT scan and BMB. In NHL, all 17 cases of T-NHL had concordant PET and BMB results. In patients with aggressive B-NHL, BMB and PET/CT agreed in 58 patients (92%) and disagreed in five (8%), while the corresponding rates in indolent B-cell lymphoma were 14 (67%) and seven patients (33%), respectively. All seven were falsely negative.

CONCLUSIONS

PET/CT upstages 17% of cases and detects occult splenic involvement. This may have potential therapeutic and prognostic implications. SUV >10 may predict for an aggressive histology. Except for indolent B-NHL, our data show that PET scans have a good overall NPV in excluding lymphomatous bone marrow involvement. This is particularly true of early-stage HL, suggesting that BMB may be safely omitted in this group.

Central nervous system (CNS) relapse in diffuse large B cell lymphoma (DLBCL): pre- and post-rituximab

Central nervous system (CNS)-directed prophylactic intrathecal (IT) therapy is indicated in patients with Burkitt and acute lymphoblastic lymphoma. Its role in diffuse large B cell lymphoma (DLBCL), a heterogeneous subtype, is less well defined. While addition of rituximab to standard cyclophosphamide-hydroxydaunorubicin-oncovin-prednisone (CHOP) chemotherapy (R-CHOP) has improved the outcomes of DLBCL patients, its role in reducing CNS relapse is unclear. We aim to (1) evaluate the clinical risk factors predictive of CNS relapse, (2) the role of rituximab in influencing CNS relapse, and (3) role of intrathecal prophylaxis. Four hundred ninety-nine patients with DLBCL from 2000 to 2008 were included (CHOP 179 vs. R-CHOP 320). IT prophylaxis was administered to 82 patients based on our institution's guidelines. Baseline characteristics between CHOP- and R-CHOP-treated patients were similar. Although R-CHOP significantly increased the complete remission rate from 71% to 81% (P < 0.01), CNS relapse rates remained unchanged (R-CHOP 6% vs. CHOP 5.1%). On multivariate analysis, poor performance status (Eastern Cooperative Oncology Group >1; hazard ratio (HR) = 2.01, 95% confidence interval (CI) 1.29-3.14), failure to attain remission (non-complete response (CR) vs. CR: HR = 2.39, 95% CI = 1.03 to 5.51), testicular (HR = 6.67, 95% CI = 1.62 to 27.53), kidney (HR = 20.14, 95% CI = 5.23 to 77.46), and breast involvement (HR = 6.14, 95% CI = 1.61 to 23.37) were each independently predictive of CNS relapse. Use of IT prophylaxis did not appear to decrease CNS relapse. Median survival after CNS relapse was 3.2 months. CNS relapse, a fatal event, remains a challenge in R-CHOP-treated patients. IT prophylaxis may not be sufficient to reduce CNS relapse, and strategies including systemic agents with high CNS penetration should be evaluated in high-risk patients identified in this study.

Recurrence after Successful Percutaneous Endoscopic Lumbar Discectomy

The purpose of this study is to investigate the risk factors for recurrence after successful percutaneous endoscopic lumbar discectomy (PELD). Recently, PELD has become the most common surgical technique. However, there are only a few studies on the factors causing the reappearance of the symptoms. Between January 2002 and December 2004, 42 patients with recurrent disc herniation after successful PELD were classified as a recurrent group and 42 patients who underwent PELD with a satisfactory result were randomly selected for a non-recurrent group. For all the patients, we analyzed the medical records and radiological studies retrospectively. The patients' mean age was 47.4 years (range: 18-76) in the recurrent group, while the mean age of the non-recurrent group was 34.4 years (range: 17-66) (p=0.001). The body mass index was 24.9 in the recurrent group and 22.9 in the non-recurrent group (p=0.006). On the radiological studies, the protrusion (p=0.013) and the presence of Modic change (p=0.003) were more frequent in the recurrent group. For the successful PELD, it is desirable for the surgeon to consider the above risk factors carefully.

Risk of hepatitis B virus (HBV) reactivation in hepatitis B surface antigen negative/hepatitis B core antibody positive patients receiving rituximab-containing combination chemotherapy without routine antiviral prophylaxis

The use of rituximab has been associated with increased risk of hepatitis B virus (HBV) reactivation in patients who are hepatitis B surface antigen (HBsAg) negative and antihepatitis B core antibody (anti-HBc) positive. We aim to determine the rate of HBV reactivation in this group of patients who received rituximab-containing combination chemotherapy without concomitant antiviral prophylaxis and to identify potential risk factors for reactivation. Sixty-two HBsAg negative/anti-HBc positive patients with B-cell lymphoma treated with rituximab-based immunochemotherapy from 2006 to 2009 were included. None of the patients received concomitant antiviral prophylaxis. In this cohort, 48 (77%) patients received rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), eight (13%) received rituximab with cyclophosphamide, vincristine and prednisolone, and six (10%) received other chemotherapy regimens. Two patients suffered HBV reactivation; both were above 70 years of age, received R-CHOP chemotherapy and were negative for antihepatitis B surface antibody (anti-HBs) at baseline. One of the two patients reactivated shortly after completion of R-CHOP chemotherapy while the other reactivated during rituximab maintenance treatment. Thus, the overall reactivation rate in this cohort of patients is 3% (2/62), 4% (2/48), and 25% (1/4) in patients who received R-CHOP chemotherapy and who received rituximab maintenance, respectively. The rate of HBV reactivation is low in patients who are HBsAg negative/anti-HBc positive receiving rituximab-based combination chemotherapy without concomitant antiviral prophylaxis. However, elderly patients, particularly those without anti-HBs, seemed particularly at risk.

Regulation of hydrogen utilisation in Rhizobium japonicum by cyclic AMP

Utilisation (uptake) of hydrogen gas by whole cells of Rhizobium japonicum was found to be influenced by the carbon source(s) present in the growth medium, with activity being highest in a medium containing sugars. Tricarboxylic acid cycle intermediates, such as malate, significantly reduced H2 utilisation. No reduction in the hydrogenase activity is observed when the enzyme is assayed directly by the tritium exchange method, indicating that the decrease in hydrogen uptake activity is not due to repression of hydrogenase biosynthesis. Cyclic AMP was found to alleviate the inhibition of H2 uptake by malate, and this requires new protein synthesis. Addition of chloramphenicol or rifampicin simultaneously with cyclic AMP eliminated the stimulation of H2 uptake in the malate medium. These results show that in R. japonicum cyclic AMP plays a major role in the regulation of H2 metabolism.

Genetic risk of extranodal natural killer T-cell lymphoma: a genome-wide association study

BACKGROUND

Extranodal natural killer T-cell lymphoma (NKTCL), nasal type, is a rare and aggressive malignancy that occurs predominantly in Asian and Latin American populations. Although Epstein-Barr virus infection is a known risk factor, other risk factors and the pathogenesis of NKTCL are not well understood. We aimed to identify common genetic variants affecting individual risk of NKTCL.

METHODS

We did a genome-wide association study of 189 patients with extranodal NKTCL, nasal type (WHO classification criteria; cases) and 957 controls from Guangdong province, southern China. We validated our findings in four independent case-control series, including 75 cases from Guangdong province and 296 controls from Hong Kong, 65 cases and 983 controls from Guangdong province, 125 cases and 1110 controls from Beijing (northern China), and 60 cases and 2476 controls from Singapore. We used imputation and conditional logistic regression analyses to fine-map the associations. We also did a meta-analysis of the replication series and of the entire dataset.

FINDINGS

Associations exceeding the genome-wide significance threshold (p<5 × 10(-8)) were seen at 51 single-nucleotide polymorphisms (SNPs) mapping to the class II MHC region on chromosome 6, with rs9277378 (located in HLA-DPB1) having the strongest association with NKTCL susceptibility (p=4·21 × 10(-19), odds ratio [OR] 1·84 [95% CI 1·61-2·11] in meta-analysis of entire dataset). Imputation-based fine-mapping across the class II MHC region suggests that four aminoacid residues (Gly84-Gly85-Pro86-Met87) in near-complete linkage disequilibrium at the edge of the peptide-binding groove of HLA-DPB1 could account for most of the association between the rs9277378*A risk allele and NKTCL susceptibility (OR 2·38, p value for haplotype 2·32 × 10(-14)). This association is distinct from MHC associations with Epstein-Barr virus infection.

INTERPRETATION

To our knowledge, this is the first time that a genetic variant conferring an NKTCL risk is noted at genome-wide significance. This finding underlines the importance of HLA-DP antigen presentation in the pathogenesis of NKTCL.

FUNDING

Top-Notch Young Talents Program of China, Special Support Program of Guangdong, Specialized Research Fund for the Doctoral Program of Higher Education (20110171120099), Program for New Century Excellent Talents in University (NCET-11-0529), National Medical Research Council of Singapore (TCR12DEC005), Tanoto Foundation Professorship in Medical Oncology, New Century Foundation Limited, Ling Foundation, Singapore National Cancer Centre Research Fund, and the US National Institutes of Health (1R01AR062886, 5U01GM092691-04, and 1R01AR063759-01A1).

Understanding the Psychological Impact of COVID-19 Pandemic on Patients With Cancer, Their Caregivers, and Health Care Workers in Singapore

PURPOSE

The coronavirus disease 2019 (COVID-19) pandemic has had a global impact, and Singapore has seen 33,000 confirmed cases. Patients with cancer, their caregivers, and health care workers (HCWs) need to balance the challenges associated with COVID-19 while ensuring that cancer care is not compromised. This study aimed to evaluate the psychological effect of COVID-19 on these groups and the prevalence of burnout among HCWs.

METHODS

A cross-sectional survey of patients, caregivers, and HCWs at the National Cancer Centre Singapore was performed over 17 days during the lockdown. The Generalized Anxiety Disorder-7 and Maslach Burnout Inventory were used to assess for anxiety and burnout, respectively. Self-reported fears related to COVID-19 were collected.

RESULTS

A total of 624 patients, 408 caregivers, and 421 HCWs participated in the study, with a response rate of 84%, 88%, and 92% respectively. Sixty-six percent of patients, 72.8% of caregivers, and 41.6% of HCWs reported a high level of fear from COVID-19. The top concern of patients was the wide community spread of COVID-19. Caregivers were primarily worried about patients dying alone. HCWs were most worried about the relatively mild symptoms of COVID-19. The prevalence of anxiety was 19.1%, 22.5%, and 14.0% for patients, caregivers, and HCWs, respectively. Patients who were nongraduates and married, and caregivers who were married were more anxious. The prevalence of burnout in HCWs was 43.5%, with more anxious and fearful HCWs reporting higher burnout rates.

CONCLUSION

Fears and anxiety related to COVID-19 are high. Burnout among HCWs is similar to rates reported prepandemic. An individualized approach to target the specific fears of each group will be crucial to maintain the well-being of these vulnerable groups and prevent burnout of HCWs.

What constitutes a normal seminal analysis? Semen parameters of 243 fertile men

A cross-sectional study was conducted to determine the semen parameters (i.e. volume, concentration, motility, viability and normal morphology) of proven fertile males in Singapore and compare it with the World Health Organization (WHO) recommended normal values and to examine some factors that may affect spermatogenesis. A total of 243 men, whose wives were pregnant at the time of collection of semen, provided a semen sample each after sexual abstinence for 3 days. A questionnaire was used to elicit occupational exposure, alcoholic consumption, smoking history and past significant medical history. Most subjects had normal sperm volume (56.4%), concentration (79.8%), motility (69.5%) and viability (53.5%) based on WHO criteria. However, fertile men had a low mean percentage of normal sperm morphology (20.0%), although they were normally distributed. Cigarette smoking was associated with significantly lower semen volumes even after adjusting for alcohol consumption. The sperm parameters (i.e. volume, density, motility, viability and normal morphology) were not significantly associated with ethnic differences. The WHO criterion for normal sperm morphology is too stringent, and should be adopted with caution. Normal sperm morphology is but one of many parameters for assessment of fertility. Social alcohol consumption, cigarette smoking, and 'recent fever' did not appear to affect sperm quality in this group of fertile men.

Beyond first-line non-anthracycline-based chemotherapy for extranodal NK/T-cell lymphoma: clinical outcome and current perspectives on salvage therapy for patients after first relapse and progression of disease

Background

Current standard treatment, including non-anthracycline-based chemotherapy and optimal combining of radiotherapy, has dramatically improved outcomes of patients with extranodal natural killer/T-cell lymphoma (ENKTL) during the last decade. This study was conducted to investigate the clinical outcome of ENKTL patients with relapsed or progressive disease after initial current standard therapy.

Patients and methods

We retrospectively reviewed patients diagnosed with ENKTL at six centers in four countries (China, France, Singapore, and South Korea) from 1997 to 2015 and analyzed 179 patients who had relapsed or progressed after initial current standard therapy.

Results

After a median follow-up of 58.6 months (range 27.9-89.2), the median second progression-free survival (PFS) was 4.1 months [95% confidence interval (CI) 3.04-5.16] and overall survival (OS) was 6.4 months (95% CI 4.36-8.51). Multivariate Cox-regression analysis revealed that elevated lactate dehydrogenase, multiple extranodal sites (≥2), and presence of B symptoms were associated with inferior OS (P < 0.05). OS and PFS were significantly different according to both prognostic index of natural killer lymphoma (PINK) and PINK-E (Epstein-Barr virus) models. Salvage chemotherapy with l-asparaginase (l-Asp)-based regimens showed a significantly better clinical benefit to response rate and PFS, although it did not lead to OS improvement. First use of l-Asp in the salvage setting and l-Asp rechallenge at least 6 months after initial treatment were the best candidates for salvage l-Asp containing chemotherapy.

Conclusions

Most patients with relapsed or refractory ENKTL had poor prognosis with short survival. Further studies are warranted to determine the optimal treatment of patients with relapsed or refractory ENKTL.