Citations

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.

Cellular senescence defines an irreversible cell growth arrest state linked to loss of tissue function and aging in mammals. This transition from proliferation to senescence is typically characterized by increased expression of the cell-cycle inhibitor p16 INK4a and formation of senescence-associated heterochromatin foci (SAHF). SAHF formation depends on HIRA-mediated nucleosome assembly of histone H3.3, which is regulated by the serine/threonine protein kinase Pak2. However, it is unknown if Pak2 contributes to cellular senescence. Here, we show that depletion of Pak2 delayed oncogene-induced senescence in IMR90 human fibroblasts and oxidative stress–induced senescence of mouse embryonic fibroblasts (MEFs), whereas overexpression of Pak2 accelerated senescence of IMR90 cells. Importantly, depletion of Pak2 in BubR1 progeroid mice attenuated the onset of aging-associated phenotypes and extended life span. Pak2 is required for expression of genes involved in cellular senescence and regulated the deposition of newly synthesized H3.3 onto chromatin in senescent cells. Together, our results demonstrate that Pak2 is an important regulator of cellular senescence and organismal aging, in part through the regulation of gene expression and H3.3 nucleosome assembly.

AbstractObjectiveThis study assesses the attitudes and preferences of Chinese clinicians toward their involvement in shared decision making (SDM).MethodsFrom May 2014 to May 2015, 200 Chinese clinicians from two hospitals were enrolled to complete a survey on their attitude towards SDM. We conducted the survey via face‐to‐face interviews before and after an educational intervention on SDM among young Chinese clinicians. The clinicians were asked to give the extent of agreement to SDM. They also gave the extent of difficulty in using decision aids (DAs) during the SDM process. The variation in the range of responses to each question before and after the SDM intervention was recorded. The frequency of changed responses was analyzed by using JMP 6.0 software. Data were statistically analyzed using Chi‐square and Mann–Whitney U tests, as appropriate to the data type. Multiple logistic regressions were used to test for those factors significantly and independently associated with preference for an approach for each scenario.ResultsOf the 200 young Chinese clinicians sampled, 59.0% indicated a preference for SDM and a desire to participate in SDM before receiving education or seeing the DA, and this number increased to 69.0% after seeing the DA with the sample video of the SDM process on Statin Choice. However, 28.5% of the respondents still reported that, in their current practice, they make clinical decisions on behalf of their patients. The clinicians who denied a desire to use the DA stated that the main barriers to implement SDM or DA use in China are lack of time and knowledge of SDM.ConclusionsMost young Chinese clinicians want to participate in SDM. However, they state the main barriers to perform SDM are lack of experience and time. The educational intervention about SDM that exposes clinicians to DAs was found to increase their receptivity.

Background:Mutations in isocitrate dehydrogenase 1 (IDH1) occur in ∼4% of patients with myelodysplastic syndrome (MDS) and have been linked with increased transformation to acute myeloid leukemia (AML). Ivosidenib (IVO; AG‐120) is an oral, potent, targeted inhibitor of the mutant IDH1 protein (mIDH1) that is approved for the treatment of adults with mIDH1 relapsed or refractory (R/R) AML. Through inhibition of mIDH1, IVO suppresses production of the oncometabolite 2‐hydroxyglutarate, leading to clinical responses via differentiation of malignant cells.Aims:To report safety and efficacy data from patients with R/R MDS enrolled in the first‐in‐human, phase 1, dose escalation and expansion study of IVO in patients with mIDH1 advanced hematologic malignancies (NCT02074839).Methods:This ongoing study is evaluating the safety, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and clinical activity of IVO. Enrollment was completed on May 8, 2017. In dose escalation, patients received single‐agent IVO orally (dose range, 200–1200 mg daily) in 28‐day cycles. The MTD was not reached and 500 mg QD was selected as the dose for expansion. The overall response rate (ORR) for MDS was defined as complete remission (CR) + partial remission + marrow CR (mCR) according to International Working Group 2006 criteria for MDS. Exploratory biomarker assessments included baseline co‐occurring mutations (next‐generation sequencing panel for hematologic malignancies) and mIDH1 variant allele frequency (VAF) in bone marrow mononuclear cells (BEAMing Digital PCR; lower limit of detection for mIDH1, 0.02–0.04%).Results:Baseline characteristics of the 12 patients with R/R MDS who received 500 mg IVO once daily were: 9 men/3 women; median age 72.5 years (range 52–78), and 42% were ≥75 years of age; median number of prior therapies 1 (range 1–3). As of Nov 2, 2018, 3 of 12 (25.0%) patients remained on treatment; 9 (75.0%) had discontinued (one for allogeneic stem cell transplantation). Median duration of exposure to IVO was 11.4 months (range 3.3–42.5). Adverse events (AEs) of any grade, irrespective of causality, occurring in ≥20% of the 12 patients were diarrhea, fatigue, back pain, rash (n = 4 each, 33.3%), anemia, urinary tract infection, decreased appetite, hypokalemia, arthralgia, dyspnea, pruritus, and hypotension (n = 3 each, 25.0%). No AEs led to permanent discontinuation of treatment. IDH differentiation syndrome was observed in 1 of 12 (8.3%) patients (grade 2). Electrocardiogram QT prolonged was reported in 2 of 12 patients (17%; grade 1 in 1 patient and grade 2 in 1 patient). Five of 12 patients achieved CR (41.7%; 95% CI 15.2%, 72.3%), 1 achieved PR (8.3%), and 5 achieved mCR (41.7%), resulting in an ORR of 91.7% (95% CI 61.5%, 99.8%). The median duration of CR was not estimable (NE) at the time of datacutoff and the median duration of response was 21.4 months (95% CI 2.3, NE). At 12 months, 60.0% of patients remained in CR. Among 5 patients who were transfusion dependent at baseline, 4 became transfusion independent for ≥56 consecutive days on treatment. Baseline co‐occurring mutations and changes in mIDH1 VAF levels will be presented.Summary/Conclusion:In patients with mIDH1 R/R MDS, IVO monotherapy was well tolerated and induced durable remissions and transfusion independence. These findings support the role of IVO as an effective, oral, targeted treatment for patients with mIDH1 R/R MDS.

Background:Lenalidomide plus rituximab (R2) has established efficacy and a tolerable safety profile in patients with previously untreated and relapsed/refractory (R/R) indolent NHL. This includes patients with marginal zone lymphoma (MZL) who are generally treated in a similar manner to follicular lymphoma (FL).Aims:Primary results for the AUGMENT study in R/R FL grade 1–3a and MZL showed significantly improved progression‐free survival (PFS) for R2 over R/placebo in the overall population and in the subgroup analyses, with the exception of the MZL subgroup. Given the small sample size for MZL patients, post hoc analyses of baseline characteristics and univariate/multivariate analyses of PFS were conducted to examine possible explanations for these results.Methods:The phase III AUGMENT study randomized patients 1:1 to R2 (lenalidomide PO 20 mg/day (d), d1–21/28 X12 cycles plus rituximab IV 375 mg/m2 weekly in cycle 1 and d1 of cycles 2–5) or rituximab‐placebo (R/placebo; same dosing schedule). PFS by 2007 IWG (without PET) was the primary endpoint. Post hoc Cox regression models were used for univariate analysis of one risk factor and multivariate analyses including treatment arm and significant risk factors (P < 0.05) from the univariate analyses.Results:A total of 63/358 (18%) MZL patients were part of the overall study population, including n = 14/16 MALT, n = 9/6 splenic, and n = 8/10 nodal MZL subtypes for respective R2 and R/placebo arms. Numerical differences between treatment arms for baseline demographics and disease characteristics for MZL patients favoring the R/placebo arm were: fewer R2 patients had an ECOG score of 0 (55% R2 vs 72% R/placebo), and more R2 (vs R/placebo) patients were older (≥65 y: 68% vs 59%; ≥70 y: 42% vs 38%), were refractory to the last prior regimen (13% vs 3%), had Ann Arbor stage IV disease at enrollment (65% vs 41%), high‐risk MALT‐IPI score (50% vs 19%), elevated LDH (29% vs 19%), B symptoms (13% vs 3%), and high tumor burden per GELF criteria (65% vs 56%). The most common grade 3/4 AEs for MZL patients receiving R2 vs R/placebo, respectively, were neutropenia (47% vs 16%), pneumonia (3% vs 13%), and leukopenia (10% vs 0). A total of 5 deaths occurred in the R2 arm (most associated with progression of disease; 2 deaths occurred early at 3 and 13 days after randomization [one prior to receiving R2 and one 2 days after treatment initiation]) and 2 in the R/placebo arm. Despite worse prognostic features, best response was improved with R2 (vs R/placebo) with ORR = 65% vs 44% (P = 0.13) and CR = 29% vs 13% (P = 0.13), although neither were statistically significant. Improved response rates did not translate into a survival advantage for R2. Median PFS for MZL patients was 20.2 mo R2 vs 25.2 mo R/placebo (HR = 1.00; 95% CI, 0.47–2.13; P = 1.0). Univariate analyses showed that several baseline factors were prognostic for MZL patients (P < 0.05): Ann Arbor stage IV, elevated LDH, and unfit for chemotherapy (Table). Multivariate analyses adjusting for the imbalance in these 3 significant prognostic factors showed an adjusted PFS HR of 0.51 (95% CI, 0.20–1.28) favoring the R2 arm, similar to the PFS HR in the overall population (HR = 0.46; 95% CI, 0.34–0.63). The univariate and multivariate analyses suggested that the imbalance in baseline prognostic factors impacted PFS results for MZL patients.Summary/Conclusion:Overall, these findings suggest that the PFS results in MZL patients were negatively impacted by the imbalance in baseline prognostic factors and more aggressive disease in the R2 over the R/placebo arm.image

Exhausted-like CD8 + resident memory T cells in the lung limit immune activation–driven fibrosis.

Abstract HLA-haploidentical hematopoietic cell transplantation (Haplo-HCT) using posttransplantation cyclophosphamide (PT-Cy) has improved donor availability. However, a matched sibling donor (MSD) is still considered the optimal donor. Using the Center for International Blood and Marrow Transplant Research database, we compared outcomes after Haplo-HCT vs MSD in patients with acute myeloid leukemia (AML) in first complete remission (CR1). Data from 1205 adult CR1 AML patients (2008-2015) were analyzed. A total of 336 patients underwent PT-Cy–based Haplo-HCT and 869 underwent MSD using calcineurin inhibitor–based graft-versus-host disease (GVHD) prophylaxis. The Haplo-HCT group included more reduced-intensity conditioning (65% vs 30%) and bone marrow grafts (62% vs 7%), consistent with current practice. In multivariable analysis, Haplo-HCT and MSD groups were not different with regard to overall survival (P = .15), leukemia-free survival (P = .50), nonrelapse mortality (P = .16), relapse (P = .90), or grade II-IV acute GVHD (P = .98). However, the Haplo-HCT group had a significantly lower rate of chronic GVHD (hazard ratio, 0.38; 95% confidence interval, 0.30-0.48; P &lt; .001). Results of subgroup analyses by conditioning intensity and graft source suggested that the reduced incidence of chronic GVHD in Haplo-HCT is not limited to a specific graft source or conditioning intensity. Center effect and minimal residual disease–donor type interaction were not predictors of outcome. Our results indicate a lower rate of chronic GVHD after PT-Cy–based Haplo-HCT vs MSD using calcineurin inhibitor–based GVHD prophylaxis, but similar other outcomes, in patients with AML in CR1. Haplo-HCT is a viable alternative to MSD in these patients.

Objectives Re-rupture is common after primary flexor tendon repair. Characterization of the biological changes in the ruptured tendon stumps would be helpful, not only to understand the biological responses to the failed tendon repair, but also to investigate if the tendon stumps could be used as a recycling biomaterial for tendon regeneration in the secondary grafting surgery. Methods A canine flexor tendon repair and failure model was used. Following six weeks of repair failure, the tendon stumps were analyzed and characterized as isolated tendon-derived stem cells (TDSCs). Results Failed-repair stump tissue showed cellular accumulation of crumpled and disoriented collagen fibres. Compared with normal tendon, stump tissue had significantly higher gene expression of collagens I and III, matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and insulin-like growth factor (IGF). The stump TDSCs presented both mesenchymal stem and haematopoietic cell markers with significantly increased expression of CD34, CD44, and CD90 markers. Stump TDSCs exhibited similar migration but a lower proliferation rate, as well as similar osteogenic differentiation but a lower chondrogenic/adipogenic differentiation capability, compared with normal TDSCs. Stump TDSCs also showed increasing levels of SRY-box 2 (Sox2), octamer-binding transcription factor 4 (Oct4), tenomodulin (TNMD), and scleraxis (Scx) protein and gene expression. Conclusion We found that a failed repair stump had increased cellularity that preserved both mesenchymal and haematopoietic stem cell characteristics, with higher collagen synthesis, MMP, and growth factor gene expression. This study provides evidence that tendon stump tissue has regenerative potential. Cite this article: C-C. Lu, T. Zhang, R. L. Reisdorf, P. C. Amadio, K-N. An, S. L. Moran, A. Gingery, C. Zhao. Biological analysis of flexor tendon repair-failure stump tissue: A potential recycling of tissue for tendon regeneration. Bone Joint Res 2019;8:232–245. DOI: 10.1302/2046-3758.86.BJR-2018-0239.R1.

AbstractIntroductionAutonomic modulation has been used as a therapy to control recurrent ventricular arrhythmia (VA). This study was to explore stellate ganglion block (SGB) effect on cardiac electrophysiologic properties and evaluate the long‐term outcome of cardiac sympathetic denervation (CSD) for patients with recurrent VA and structural heart disease (SHD).Materials and MethodsPatients who had recurrent VA due to SHD were enrolled prospectively. Electrophysiologic study and ventricular tachycardia (VT) induction were performed before and after left and right SGB. VA burden and long‐term outcomes were assessed for a separate patient group who underwent left or bilateral CSD for drug‐refractory VA due to SHD.ResultsElectrophysiologic study of nine patients showed that baseline mean (SD) corrected sinus node recovery time (cSNRT) increased from 320.4 (73.3) ms to 402.9 (114.2) ms after left and 482.4 (95.7) ms after bilateral SGB (P = .03). SGB did not significantly change P‐R, QRS, and Q‐T intervals and ventricular effective refractory period, nor did the inducibility of VA. Nineteen patients underwent left (n = 14) or bilateral (n = 5) CSD. CSD reduced VA burden and appropriate ICD therapies from a median (interquartile range) of 2.5 (0.4‐11.6) episodes weekly to 0.1 (0.0‐2.4) episodes weekly at 6‐month follow‐up (P = .002). Three‐year freedom from orthotopic heart transplant (OHT) and death was 52.6%. New York Heart Association functional class III/IV and VT rate less than 160 beats per minute were predictors of recurrent VA, OHT, and death.ConclusionSGB increased cSNRT without changing heart rate. CSD was more beneficial for patients with mild‐to‐moderate heart failure and faster VA.