Citations

Abstract Fibroproliferative diseases are a leading cause of morbidity and mortality featuring localized and systematic tissue/organ fibrosis, which account for nearly 45% of all deaths in the developed world, with an unknown etiology and no effective treatment. Transforming growth factor beta (TGF-β) is a ubiquitous cytokine that contributes to fibroblast activation, myofibroblast differentiation, collagen overproduction and pathological tissue fibrosis. In that mounting evidence indicate that altered glutamine metabolism has critical roles in regulating signaling pathways, maintaining redox balance and macromolecular biosynthesis, we wished to test the general hypothesis that intervention of these metabolic processes could provide novel approaches to developing anti-fibrotic therapies. To that end, in the current work we provide a framework integrating glutamine dysregulation with profibrotic TGF-β signaling. We found that Glutaminase 1 (GLS1), which converts glutamine to glutamate, is induced by TGF-β and is also elevated in (i) fibroblasts isolated from Idiopathic Pulmonary Fibrosis (IPF) patients; and (ii) the murine bleomycin (i.e., TGF-β driven) model of lung fibrosis. While phosphorylation of Smad2 and Smad3 occurs independently of GLS1, TGF-β stimulated expression of profibrotic targets (i.e., Collagen I, PAI-1, CTGF, α-SMA and fibronectin) as well as biological actions (i.e., cell migration and anchorage independent growth) require GLS1 activity. Moreover, knockdown of Smad2 or Smad3 as well as inhibition of MAPK, PI3K, Akt or mTOR abrogates the induction of GLS1 by TGF-β; documenting that TGF-β regulates GLS1 expression via both Smad and non-Smad signaling. As GLS1 represents a critical component mediating the fibroproliferative actions of TGF-β, in order to identify the operative molecular mechanism(s) we focused on (i) a group of histone deacetylases called sirtuins (SIRT) which are known to elicit antifibrotic effects; and (ii) the Forkhead box protein O4 (FOXO4) transcription factor which has been shown to bind the GLS1 promoter. We found that there is not only a decrease in SIRT7 and FOXO4 coincident with the induction of GLS1 by TGF-β, but TGF-β inhibits SIRT7 deacetylation activity which in turn prevents FOXO4 deacetylation and inhibition of GLS1 expression. Last, consistent with SIRT7 and FOXO4 being negative regulators of profibrotic TGF-β signaling, their levels were also decreased in IPF fibroblasts and bleomycin-induced lung fibrosis. These studies point to an exciting, novel and unexplored connection between sirtuins, FOXOs and glutamine metabolism by elucidating the mechanism(s) by which epigenetic and transcriptional processes cooperate to regulate glutamine metabolism and fibrotic development in a TGF-β dependent manner. Citation Format: Malay Choudhury, Xueqian Yin, Jeong-Han Kang, Mahefatiana Andrianifahanana, Edward B. Leof. Cooperativity between glutaminase 1 and histone deacetylase SIRT7 regulates TGF-β mediated lung fibrosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1847.

Rewarming the intact heart after a period of hypothermia is associated with reduced myocardial contractility, decreased Ca2+ sensitivity, and increased cardiac troponin-I (cTnI) phosphorylation. We hypothesized that hypothermia/rewarming (H/R) induces left ventricular (LV) contractile dysfunction due to phosphorylation of cTnI at Ser23/24. To test this hypothesis, the response of wild-type mice ( n = 7) to H/R was compared with transgenic (TG) mice expressing slow skeletal TnI (TG-ssTnI; n = 7) that lacks the Ser23/24 phosphorylation sites. Hypothermia was induced by surface cooling and maintained at 23–25°C for 3 h. Subsequently, the animals were rewarmed to 37°C. LV systolic and diastolic function was assessed using a 1.4 F pressure-volume Millar catheter introduced via the right carotid artery. At baseline conditions, there were no significant differences in LV systolic function between wild-type and TG-ssTnI mice, whereas measurements of diastolic function [isovolumic relaxation constant (τ) and end-diastolic pressure-volume relationship (EDPVR)] were significantly ( P < 0.05) reduced in TG-ssTnI animals. Immediately after rewarming, significant differences between groups were found in cardiac output (CO; wild-type 6.6 ± 0.7 vs. TG-ssTnI 8.8 ± 0.7 mL/min), stroke work (SW; wild-type 796 ± 112 vs. TG-ssTnI 1208 ± 67 mmHg/μL), and the preload recruited stroke work (PRSW; wild-type 38.3 ± 4.9 vs. TG-ssTnI 68.8 ± 8.2 mmHg). However, EDPVR and τ returned to control levels within 1 h in both groups. We conclude that H/R-induced LV systolic dysfunction results from phosphorylation of cTnI at Ser23/24. NEW & NOTEWORTHY Rewarming following a period of accidental hypothermia leads to a form of acute cardiac failure (rewarming shock), which is in part due to reduced sensitivity to Ca2+ activation of myocardial contraction. The results of the present study support the hypothesis that rewarming shock is due to phosphorylation of cardiac troponin I.

Background and Purpose— Hypertrophic cardiomyopathy patients with atrial fibrillation are at increased risk of stroke, and anticoagulation is strongly recommended. However, limited data are available regarding the safety and effectiveness of non–vitamin K antagonist oral anticoagulants (NOACs) for primary prevention of stroke. Methods— Using the Korean Health Insurance Review and Assessment Service database, we identified 2397 patients with hypertrophic cardiomyopathy and nonvalvular atrial fibrillation on oral anticoagulation from 2013 to 2016 without history of ischemic stroke, intracranial hemorrhage (ICH), or gastrointestinal bleeding (992 on warfarin and 1405 on NOACs). Inverse probability of treatment weighting with propensity scores was used to balance covariates between treatment groups. Risk for ischemic stroke, ICH, gastrointestinal bleeding, death, and their composite outcome associated with NOAC use was assessed with warfarin use as the reference. Results— During a mean follow-up of 1.6 years, the incidence rates of ischemic stroke, ICH, gastrointestinal bleeding, death, and composite outcome were all significantly lower in the NOAC than in the warfarin group (stroke, 2.8 versus 5.0; ICH, 0.5 versus 1.3; gastrointestinal bleeding, 2.3 versus 3.0; death, 3.0 versus 5.1; composite, 7.5 versus 12.5 events per 100 person-years). NOACs were associated with significantly lower risks of ischemic stroke (hazard ratio [HR], 0.47; 95% CI, 0.32–0.68), ICH (HR, 0.31; 95% CI, 0.14–0.69), gastrointestinal bleeding (HR, 0.62; 95% CI, 0.40–0.96), death (HR, 0.45; 95% CI, 0.31–0.65), and the composite outcome (HR, 0.48; 95% CI, 0.38–0.61) than warfarin. The same trend was observed regardless of the NOAC dose and across various high-risk subgroups. In analysis of individual NOACs, all NOACs were associated with lower risks of ischemic stroke and composite outcome. Conclusions— NOACs showed superior effectiveness and safety versus warfarin in the primary prevention of stroke versus warfarin in real-world Asian hypertrophic cardiomyopathy with atrial fibrillation.

Abstract Zanubrutinib is a potent and highly selective inhibitor of Bruton tyrosine kinase (BTK). In this first-in-human, open-label, multicenter, phase 1 study, patients in part 1 (3 + 3 dose escalation) had relapsed/refractory B-cell malignancies and received zanubrutinib 40, 80, 160, or 320 mg once daily or 160 mg twice daily. Part 2 (expansion) consisted of disease-specific cohorts, including treatment-naive or relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). The primary end points were safety and tolerability, and definition of the maximum tolerated dose (part 1). Additional end points included pharmacokinetics/pharmacodynamics and preliminary efficacy. Reported herein are results from 144 patients enrolled in the dose-finding and CLL/SLL cohorts. No dose-limiting toxicities occurred in dose escalation. Median BTK occupancy in peripheral blood mononuclear cells was &gt;95% at all doses. Sustained complete (&gt;95%) BTK occupancy in lymph node biopsy specimens was more frequent with 160 mg twice daily than 320 mg once daily (89% vs 50%; P = .0342). Consequently, 160 mg twice daily was selected for further investigation. With median follow-up of 13.7 months (range, 0.4-30.5 months), 89 CLL/SLL patients (94.7%) remain on study. Most toxicities were grade 1/2; neutropenia was the only grade 3/4 toxicity observed in &gt;2 patients. One patient experienced a grade 3 subcutaneous hemorrhage. Among 78 efficacy-evaluable CLL/SLL patients, the overall response rate was 96.2% (95% confidence interval, 89.2-99.2). Estimated progression-free survival at 12 months was 100%. Zanubrutinib demonstrated encouraging activity in CLL/SLL patients, with a low incidence of major toxicities. This trial was registered at www.clinicaltrials.gov as #NCT02343120.

Purpose The Next Accreditation System requires training programs to demonstrate competence among trainees. Within gastroenterology (GI), there are limited data describing learning curves and structured assessment of competence in esophagogastroduodenoscopy (EGD) and colonoscopy. In this study, the authors aimed to demonstrate the feasibility of a centralized feedback system to assess endoscopy learning curves among GI trainees in EGD and colonoscopy. Method During academic year 2016–2017, the authors performed a prospective multicenter cohort study, inviting participants from multiple GI training programs. Trainee technical and cognitive skills were assessed using a validated competence assessment tool. An integrated, comprehensive data collection and reporting system was created to apply cumulative sum analysis to generate learning curves that were shared with program directors and trainees on a quarterly basis. Results Out of 183 fellowships invited, 129 trainees from 12 GI fellowships participated, with an overall trainee participation rate of 72.1% (93/129); the highest participation level was among first-year trainees (90.9%; 80/88), and the lowest was among third-year trainees (51.2%; 27/53). In all, 1,385 EGDs and 1,293 colonoscopies were assessed. On aggregate learning curve analysis, third-year trainees achieved competence in overall technical and cognitive skills, while first- and second-year trainees demonstrated the need for ongoing supervision and training in the majority of technical and cognitive skills. Conclusions This study demonstrated the feasibility of using a centralized feedback system for the evaluation and documentation of trainee performance in EGD and colonoscopy. Furthermore, third-year trainees achieved competence in both endoscopic procedures, validating the effectiveness of current training programs.

Abstract The presence of FMS-like receptor tyrosine kinase-3 internal tandem duplication (FLT3-ITD) mutations in patients with acute myeloid leukemia (AML) is associated with poor clinical outcome. FLT3 tyrosine kinase inhibitors (TKIs), although effective in kinase ablation, do not eliminate primitive FLT3-ITD+ leukemia cells, which are potential sources of relapse. Thus, understanding the mechanisms underlying FLT3-ITD+ AML cell persistence is essential to devise future AML therapies. Here, we show that expression of protein arginine methyltransferase 1 (PRMT1), the primary type I arginine methyltransferase, is increased significantly in AML cells relative to normal hematopoietic cells. Genome-wide analysis, coimmunoprecipitation assay, and PRMT1-knockout mouse studies indicate that PRMT1 preferentially cooperates with FLT3-ITD, contributing to AML maintenance. Genetic or pharmacological inhibition of PRMT1 markedly blocked FLT3-ITD+ AML cell maintenance. Mechanistically, PRMT1 catalyzed FLT3-ITD protein methylation at arginine 972/973, and PRMT1 promoted leukemia cell growth in an FLT3 methylation–dependent manner. Moreover, the effects of FLT3-ITD methylation in AML cells were partially due to cross talk with FLT3-ITD phosphorylation at tyrosine 969. Importantly, FLT3 methylation persisted in FLT3-ITD+ AML cells following kinase inhibition, indicating that methylation occurs independently of kinase activity. Finally, in patient-derived xenograft and murine AML models, combined administration of AC220 with a type I PRMT inhibitor (MS023) enhanced elimination of FLT3-ITD+ AML cells relative to AC220 treatment alone. Our study demonstrates that PRMT1-mediated FLT3 methylation promotes AML maintenance and suggests that combining PRMT1 inhibition with FLT3 TKI treatment could be a promising approach to eliminate FLT3-ITD+ AML cells.

Background:Despite advances in the treatment of lymphoma in recent years, unmet medical needs remain, particularly for patients with R/R disease and rarer subtypes of non‐Hodgkin lymphoma (NHL). The alkylating deacetylase inhibitor tinostamustine (EDO‐S101) is a novel multi‐action therapy that is designed to improve drug access to DNA strands, and at the same time induce DNA damage and counteract its repair in cancer cells.Aims:Here we report findings from the dose‐escalation stage of a Phase I first‐in‐human study to evaluate the safety and pharmacokinetics, and to determine the maximum tolerated dose (MTD) and recommended Phase II dose (RP2D), of tinostamustine in patients with R/R lymphoid malignancies (NCT02576496).Methods:Patients were recruited using a standard 3+3 design, with the first cohort receiving 20 mg/m2 tinostamustine administered iv over 60 minutes, with six ascending cohorts, to a maximum dose of 120 mg/m2. Dose‐limiting toxicities (DLT) were defined as: any Grade (G) 3 or 4 non‐haematological toxicity (excluding alopecia and easily correctable electrolyte abnormalities); nausea, vomiting or diarrhoea ≥10 days despite aggressive symptomatic treatment; G4 neutropenia or thrombocytopenia for ≥7 days; any G2 or more toxicity for >3 weeks; any toxicity resulting in a delay of the next dose administration (Cycle 2 Day 1 ≥14).Results:A total of 27 patients with lymphoid malignancies were enrolled into the study, 10 of these patients were diagnosed with R/R Hodgkin lymphoma (HL) and 17 with NHL, including peripheral T‐cell lymphoma and diffuse large B‐cell lymphoma. The MTD of tinostamustine was determined to be 100 mg/m2; shorter infusion times were evaluated in three cohorts of patients, but the recommended infusion time was confirmed as 60 minutes. Safety findings for each dose cohort for HL and NHL patients were mainly haematological toxicities: G3/4 thrombocytopenia, neutropenia and leucopenia, with incidence increasing with increasing dose. One patient experienced a G3 allergic reaction. Signals of efficacy were observed among the 27 patients with lymphoma (overall response rate [ORR] 41% [11 patients]; clinical benefit rate [CBR] 67% [18 patients]). The best response, as determined by the Investigator, was complete response (CR; 3/27 patients [11%]), which was observed in one patient with HL and two with NHL; partial response (PR; 8/27 patients [30%]) and stable disease (SD; 7/27 patients [26%]) were also observed. Nine of the 27 patients (33%) had disease progression.Summary/Conclusion:Administration of tinostamustine on Day 1 of a 21‐day cycle was well tolerated with signals of efficacy in patients with both HL and NHL, including rare forms of NHL such as peripheral T‐cell lymphoma. The RP2D for tinostamustine in lymphoid malignancies, depending on patient platelet count at treatment initiation, was determined as 80 mg/m2 for those with >100 x 109/l platelets, and 100 mg/m2 for those with ≥200 x 109/l platelets. This will be applied in the second phase of this study, where patients will be recruited into one of five different cohorts.