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.

Background: Antibiotic use may increase hospital length of stay (LOS) among older patients with advanced cancer who are transitioned to comfort measures. Methods: We studied a cohort of patients with advanced cancer aged ≥65 years who were transitioned to comfort measures during admission from July 1, 2014, through November 30, 2016. We evaluated the association between antibiotic exposure and LOS using a Poisson regression model adjusted for age, gender, cancer type, comorbidities, infection, and intensive care unit admission. Results: Among 461 patients with advanced cancer, median age was 74 years (range: 65-99), 49.0% (n = 226) were female, and 20.6% (n = 95) had liquid tumors. Overall, 82.9% (n = 382) received ≥1 antibiotic and 64.6% (n = 298) had ≥1 infection diagnosis during hospitalization. Infection diagnoses commonly included sepsis (35%, n = 161/461), pneumonia (25%, n = 117/461), and urinary tract infection (14%, n = 66/461). Among those receiving antibiotics, the most common choices included vancomycin (79%, n = 300/382), cephalosporins (63%, n = 241/382), and penicillins (45%, n = 172/382). In a multivariable Poisson regression model, LOS was 34% longer (count ratio = 1.34, [95% confidence interval: 1.20-1.51]) among those exposed versus unexposed to antibiotics. Conclusions: Antibiotic use among patients with advanced cancer who are transitioned to comfort measures is associated with longer LOS. These data illustrate the importance of tradeoffs associated with antibiotic use, such as unintended increased LOS, when striving for goal-concordant care near the end of life.

Neutrophils are vital for antimicrobial defense; however, their role during viral infection is less clear. Furthermore, the molecular regulation of neutrophil fate and function at the viral infected sites is largely elusive. Here we report that BCL6 deficiency in myeloid cells exhibited drastically enhanced host resistance to severe influenza A virus (IAV) infection. In contrast to the notion that BCL6 functions to suppress innate inflammation, we find that myeloid BCL6 deficiency diminished lung inflammation without affecting viral loads. Using a series of Cre-transgenic, reporter, and knockout mouse lines, we demonstrate that BCL6 deficiency in neutrophils, but not in monocytes or lung macrophages, attenuated host inflammation and morbidity following IAV infection. Mechanistically, BCL6 bound to the neutrophil gene loci involved in cellular apoptosis in cells specifically at the site of infection. As such, BCL6 disruption resulted in increased expression of apoptotic genes in neutrophils in the respiratory tract, but not in the circulation or bone marrow. Consequently, BCL6 deficiency promoted tissue neutrophil apoptosis. Partial neutrophil depletion led to diminished pulmonary inflammation and decreased host morbidity. Our results reveal a previously unappreciated role of BCL6 in modulating neutrophil apoptosis at the site of infection for the regulation of host disease development following viral infection. Furthermore, our studies indicate that tissue-specific regulation of neutrophil survival modulates host inflammation and tissue immunopathology during acute respiratory viral infection.

e15688 Background: PNETs are marked by histological heterogeneity and variable clinical outcomes. Other than Ki67 index, reliable circulating or tissue biomarkers for prognosis do not exist. Methods: PubMed was searched through 01/31/2017. Inclusion criteria were: 1) prospective/retrospective cohort with defined source population, boundary dates, and justifications for exclusions; 2) assay of primary tumors; 3) clear descriptions of methods including techniques and controls; 4) use of multivariate proportional hazards modeling adjusted for prognostic factors including but not limited to stage or grade; and 5) reporting adjusted hazard ratios (HR) with 95 % confidence intervals and P values. Studies with < 50 % PNETs were excluded. PNET-specific data was summarized in the table. Results: A total of 2958 manuscripts were identified and 462 manuscripts were reviewed. Only 23 multivariate studies met all inclusion criteria. These altogether analyzed 24 unique targets and 14 were associated with survival. Conclusions: This meta-analysis identified 14 markers associated with survival of PNET patients. Future studies should adhere to the REMARK criteria and incorporate the 2017 WHO grading system for multivariate analysis. 1. I-immunohistochemistry, F-fluorescence in situ hybridization, E-enzyme linked immunosorbent assay, M- methylation specific PCR, P-polymerase chain reaction; 2. O-overall survival, F-disease free survival, S-disease specific survival, P- progression free survival.[Table: see text]

Abstract Background: Invasive lobular carcinoma (ILC) of the breast has distinct histological and molecular variations compared to invasive ductal carcinoma (IDC), including absence of the adhesion protein E-cadherin. Recently, molecular subtypes within ILC have been described, with an analysis from The Cancer Genome Atlas (Ciriello et al) identifying three distinct groups within ILC based on gene expression—reactive-like, immune-related, and proliferative. In this study, we applied this 60-gene classifier to a locally advanced cohort of ILC and mixed ILC/IDC cases from patients screening for the I-SPY 2 neoadjuvant chemotherapy trial. Methods: The I-SPY 2 TRIAL is open to women with more locally advanced, clinically/molecularly (as assessed by MammaPrint) high risk breast cancer. HR+HER2- MammaPrint Low risk patients ineligible for I-SPY 2 randomization are invited to join a MP Low risk registry. 131 ILC and mixed ILC/IDC tumors from these cohorts (I-SPY 2: n=80; low risk registry: n=51) with pre-treatment Agilent microarrays were available for analysis. We used the Classification to Nearest Centroid technique to assign TCGA subtype to our cohort. We assessed association between TCGA subtype, clinical covariates and response to therapy using a chi-square test. We also evaluated the Euclidean distance between each sample and the three subtype centroids. In an exploratory analysis, we used consensus clustering based on the 1000 most varying genes within the HR+HER2- I-SPY ILC cases to generate new unsupervised groupings, and assessed the concordance with the TCGA reactive-like, immune-related and proliferative subtype assignments. Results: Of the 131 patients included, most (79%) were HR+HER2-, 11% were HR+HER2+, 2% were HR-HER2+ and 8% were HR-HER2- for a total of 10% HR-. 66 were pure ILC, while 65 were mixed ILC/IDC. Upon applying the TCGA 60-gene classifier, the distribution of ILC subtypes was as follows: 33 (25%) were classified as reactive-like, 50 (38%) were immune-related, and 48 (37%) were proliferative. 64% of triple negative cases were reactive-like; while the HR+HER2- and HER2+ cases were more likely to be in the proliferative or immune-related subtype (p=0.037). Among the 80 I-SPY 2 cases, the overall pathologic complete response rate was low (16%) but equivalent to the overall HR+HER2- I-SPY2 population (16%). This did not differ across the groups defined by the TCGA ILC subtypes (p=0.79). Interestingly, a subset of cases assigned as reactive-like and immune-related were of similar distance to the proliferative subtype centroid as patients assigned to the proliferative subtype. When we used consensus clustering to identify new subsets within our locally advanced ILC cohort, our unsupervised groupings had only 32% concordance with the TCGA ILC subtype assignments. Conclusion: The low concordance between our consensus cluster groupings and the TCGA subtype groupings may reflect underlying differences within a locally advanced cohort of ILC cases, like I-SPY, that may not be captured in the 60-gene classifier developed from the overall lower stage TCGA cohort. These findings suggest that considerable molecular heterogeneity exists in lobular cancers, which merits further investigation. Citation Format: Zhu Z, Yau C, Chien AJ, Haddad T, Esserman LJ, van't Veer L, Mukhtar RA, I-SPY2 Consortium. Molecular subtypes of invasive lobular breast cancer in the I-SPY2 TRIAL [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD7-06.