Citations

29 Background: CRS-207 is a live, attenuated, double-deleted Listeria monocytogenes (LADD) engineered to stimulate immune response to mesothelin. In a phase I trial of 60 MPM patients, 34% of subjects had tumor reduction (range -1 to -47%) following 2 doses of CRS-207 alone. In KEYNOTE-028 pembro showed activity in PDL1+ (≥1% by IHC) MPM, with an objective response rate (ORR) of 20% (5/25) and stable disease in 52% of subjects who had failed or did not receive chemotherapy. Subsequent studies of pembro have shown similar results in MPM. Results from a pre-clinical murine lung tumor model (CT26hMeso) showed anti-PD-1 enhanced LADD-induced tumor response. The study described here evaluated the efficacy of combination therapy of CRS-207/pembro. Methods: Adults with epithelial/biphasic MPM, ≤2 prior lines, progression on pemetrexed and platinum-based therapy, and no prior immunotherapies were enrolled. CRS-207/pembro were administered IV Q3W for 4 cycles, after which pembro continued Q3W and CRS-207 changed to Q6W. Response was assessed Q6W by modified RECIST for MPM (Byrne and Nowak, 2004). The primary endpoint was ORR; secondary endpoints included DOR, disease control rate (DCR), progression-free survival (PFS) and overall survival. Pre- and on-treatment blood and tumor samples were collected. Shedding and blood clearance of CRS-207 were evaluated. Results: 9/10 subjects were evaluable for response. No responses were observed; DCR was 11% (1/9 with SD) and PFS ranged from 3.4 to 8.9 weeks. Most common treatment related adverse events were chills, pyrexia and nausea. 3/10 subjects evaluated were PDL-1 negative by IHC. Of 6 subjects who underwent clearance and shedding evaluation, CRS-207 was detected in blood in 1 at 18-24 hrs after the first CRS-207 dose and cleared by the next evaluation at Day 4; shedding samples (urine, fecal, and saliva) tested negative. Conclusions: The toxicity profile of CRS-207/pembro combination was consistent with the safety profile of each component alone. No evidence of clinical activity was observed. Based on the results and an overall evaluation of the program, the clinical development of CRS-207 was discontinued. (NCT01675765) (NCT02054806). Clinical trial information: NCT03175172.

Circulating extracellular vesicles (EVs) are a novel and emerging biomarker for nonalcoholic steatohepatitis (NASH). It has been demonstrated that total circulating EVs and hepatocyte‐derived EVs are elevated in male mice with diet‐induced NASH. How hepatocyte‐derived EVs change over time and other cellular sources of EVs in NASH have not been determined. Our objective was to define the quantitative evolution of hepatocyte‐derived, macrophage‐derived, neutrophil‐derived, and platelet‐derived EVs in male and female mice with dietary NASH. Fluorescently labeled antibodies and a nanoscale flow cytometer were used to detect plasma levels of EVs. Asialoglycoprotein receptor 1 (ASGR1) and cytochrome P450 family 2 subfamily E member 1 (CYP2E1) are markers of hepatocyte‐derived EVs; galectin 3 is a marker of macrophage‐derived EVs; common epitope on lymphocyte antigen 6 complex, locus G/C1 (Ly‐6G and Ly‐6C) is a marker of neutrophil‐derived EVs; and clusters of differentiation 61 (CD61) is a marker of platelet‐derived EVs. Nonalcoholic fatty liver disease activity score (NAS) was calculated using hematoxylin and eosin‐stained liver sections, and magnetic resonance imaging (MRI) was used for measurement of the fat fraction and elastography. Hepatocyte‐derived EVs increased in both male and female mice at 12 and 10 weeks of feeding, respectively, and remained elevated at 24 weeks in both male and female mice and at 48 weeks in male mice and 36 weeks in female mice. Macrophage‐ and neutrophil‐derived EVs were significantly elevated at 24 weeks of dietary feeding concomitant with the histologic presence of inflammatory foci in the liver. In fat‐, fructose‐, and cholesterol‐ (FFC) fed male mice, platelet‐derived EVs were elevated at 12, 24, and 48 weeks, whereas in female mice, platelet derived EVs were significantly elevated at 24 weeks. Hepatocyte‐, macrophage‐ and neutrophil‐derived EVs correlated well with the histologic NAS. Conclusion: Circulating cell‐type‐specific EVs may be a novel biomarker for NASH diagnosis and longitudinal follow up.

Abstract Understanding the biological functions of tau variants can illuminate differential etiologies of Alzheimer’s disease (AD) and primary tauopathies. Though the end-stage neuropathological attributes of AD and primary tauopathies are similar, the etiology and behavioral outcomes of these diseases follow unique and divergent trajectories. To study the divergent physiological properties of tau variants on a uniform immunogenetic background, we created somatic transgenesis CNS models of tauopathy utilizing neonatal delivery of adeno-associated viruses expressing wild-type (WT) or mutant tau in non-transgenic mice. We selected four different tau variants—WT tau associated with AD, P301L mutant tau associated with frontotemporal dementia (FTD), S320F mutant tau associated with Pick’s disease and a combinatorial approach using P301L/S320F mutant tau. CNS-targeted expression of WT and P301L mutant tau results in robust tau hyperphosphorylation without tangle pathology, gradually developing age-progressive memory deficits. In contrast, the S320F variant, especially in combination with P301L, produces an AD-type tangle pathology, focal neuroinflammation and memory impairment on an accelerated time scale. Using the doubly mutated P301L/S320F tau variant, we demonstrate that combining different mutations can have an additive effect on neuropathologies and associated co-morbidities, possibly hinting at involvement of unique functional pathways. Importantly, we also show that overexpression of wild-type tau as well as an FTD-associated tau variant can lead to cognitive deficits even in the absence of tangles. Together, our data highlights the synergistic neuropathologies and associated cognitive and synaptic alterations of the combinatorial tau variant leading to a robust model of tauopathy.

AbstractThere is a clear and unmet need for biomarkers in hepatocellular carcinoma (HCC). Circulating cell free deoxyribonucleic acid (cfDNA) is a fragmented DNA subtype, found in the blood circulation. Circulating tumor DNA (ctDNA) is the fraction of total cfDNA, which originates from the primary tumor or metastases in patients with cancer. Earlier studies reported that quantitative measurement cfDNA has diagnostic and prognostic role for HCC. More recently, improvement in next-generation sequencing technology and better understanding of genetic or epigenetic alteration of HCC have allowed comprehensive analysis of mutational and methylation landscape of ctDNA. Hotspot mutation panels and methylation panels have both shown promising performance. None of these tests have yet been validated in longitudinal cohorts for preclinical detection of HCC. In this article, the authors discuss the currently available ctDNA detection technologies, their diagnostic and prognostic performance in HCC, and future research directions.

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: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.