Deciphering the mitophagy receptor network identifies a crucial role for OPTN (optineurin) in acute myeloid leukemia.

The selective autophagic degradation of mitochondria via mitophagy is essential for preserving mitochondrial homeostasis and, thereby, disease maintenance and progression in acute myeloid leukemia (AML). Mitophagy is orchestrated by a variety of mitophagy receptors whose interplay is not well understood. Here, we established a pairwise multiplexed CRISPR screen targeting mitophagy receptors to elucidate redundancies and gain a deeper understanding of the functional interactome governing mitophagy in AML. We identified OPTN (optineurin) as sole non-redundant mitophagy receptor and characterized its unique role in AML. Knockdown and overexpression experiments demonstrated that OPTN expression is rate-limiting for AML cell proliferation. In a MN1-driven murine transplantation model, loss of OPTN prolonged overall median survival by 7 days (+21%). Mechanistically, we found broadly impaired mitochondrial respiration and function with increased mitochondrial ROS, that most likely caused the proliferation defect. Our results decipher the intertwined network of mitophagy receptors in AML for both ubiquitin-dependent and receptor-mediated mitophagy, identify OPTN as a non-redundant tool to study mitophagy in the context of leukemia and suggest OPTN inhibition as an attractive therapeutic strategy.Abbreviations: AML: acute myeloid leukemia; CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats; CTRL: control; DFP: deferiprone; GI: genetic interaction; KD: knockdown; KO: knockout; ldMBM, lineage-depleted murine bone marrow; LFC: log2 fold change; LIR: LC3-interacting region; LSC: leukemic stem cell; MAGeCK: Model-based Analysis of Genome-wide CRISPR-Cas9 Knockout; MDIVI-1: mitochondrial division inhibitor 1; MOI: multiplicity of infection; MOM: mitochondrial outer membrane; NAC: N-acetyl-L-cysteine; OA: oligomycin-antimycin A; OCR: oxygen consumption rate; OE: overexpression; OPTN: optineurin; PINK1: PTEN induced putative kinase 1; ROS: reactive oxygen species; SEM: standard error of the mean; TCGA: The Cancer Genome Atlas; TEM: transmission electron microscopy; UBD: ubiquitin-binding domain; WT: wild type.

Evolution of treatment patterns and survival outcomes in patients with advanced non-small cell lung cancer treated at Frankfurt University Hospital in 2012-2018.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have improved outcomes for patients with advanced non-small cell lung cancer (NSCLC) versus chemotherapy in clinical trials. In Germany, ICIs have been used clinically since 2015 for patients with advanced/metastatic NSCLC without epidermal growth factor receptor (EGFR)/anaplastic lymphoma kinase (ALK) aberrations. As part of I-O Optimise, a multinational research program utilizing real-world data on thoracic malignancies, we describe real-world treatment patterns and survival following reimbursement of ICIs for advanced NSCLC in Germany. METHODS: This retrospective cohort study included patients with locally advanced/metastatic NSCLC without known EGFR/ALK aberrations who received a first line of therapy at Frankfurt University Hospital between January 2012 and December 2018, with follow-up to December 2019 or death, whichever occurred first. Using electronic medical records, treatment patterns and survival outcomes were described by histology (squamous cell [SQ]; non-squamous cell [NSQ]/other) and time period (pre- and post-ICI approval). RESULTS: Among eligible patients who started first-line treatment, 136 (pre-ICI) and 126 (post-ICI) had NSQ/other histology, and 32 (pre-ICI) and 38 (post-ICI) had SQ histology. Use of an ICI in the NSQ/other cohort increased from 5.9% (all second- or third-line) in the pre-ICI period to 57.1% (22.2% in first-line, including 13.5% as monotherapy and 8.7% combined with chemotherapy) in the post-ICI period. This was paralleled by a significant (P < 0.0001) prolongation of median (95% CI) OS from 9.4 (7.1-11.1) to 14.8 (12.7-20.5) months between the pre-ICI and post-ICI periods. A similar increase in the uptake of ICI was observed for the SQ cohort (from 3.1% pre-ICI [fourth-line] to 52.6% post-ICI [28.9% as first-line, including 15.8% as monotherapy and 13.2% combined with chemotherapy]); however, analysis of survival outcomes was limited by small group sizes. CONCLUSION: These real-world data complement clinical trial evidence on the effectiveness of ICIs in patients with advanced NSCLC and NSQ/other histology in Germany.

Early-onset venous thromboembolisms in newly diagnosed non-promyelocytic acute myeloid leukemia patients undergoing intensive induction chemotherapy.

OBJECTIVES AND METHODS: Venous thromboembolic (VTE) events are emerging as frequent complications in acute myeloid leukemia (AML); however, there is insufficient data regarding epidemiology, risk factors, and impact on outcomes. The optimal approach to balance risks of thrombosis and hemorrhage remains unclear. This retrospective single-center study in AML patients undergoing induction chemotherapy between 2007 and 2018 assessed incidence, risk factors, features, and outcomes of early-onset VTE. RESULTS: 423 patients (median age 59 years) were enrolled. VTE was diagnosed in 31 patients (7.3%) within 3 months of admission. The median time to VTE was 3 days. Non-central venous catheter (CVC)-related VTE occurred in 19 patients (61%). Main risk factor for VTE was leukocytosis at admission, independent of platelet counts/INR. Four patients (13%) exhibited VTE recurrence. No deaths directly related to VTE or major bleeding events associated with platelet-adjusted anticoagulation in patients with VTE were recorded. There was no clear impact of VTE on 1-year overall survival; however, non-CVC-related VTE may be associated with adverse outcomes. CONCLUSIONS: Early-onset VTE is a common complication in newly diagnosed AML patients admitted for induction chemotherapy. Leukocytosis is an independent VTE risk factor. The potentially adverse impact of non-CVC-related VTE merits further study.

Translatome proteomics identifies autophagy as a resistance mechanism to on-target FLT3 inhibitors in acute myeloid leukemia.

Internal tandem duplications (ITD) in the receptor tyrosine kinase FLT3 occur in 25 % of acute myeloid leukemia (AML) patients, drive leukemia progression and confer a poor prognosis. Primary resistance to FLT3 kinase inhibitors (FLT3i) quizartinib, crenolanib and gilteritinib is a frequent clinical challenge and occurs in the absence of identifiable genetic causes. This suggests that adaptive cellular mechanisms mediate primary resistance to on-target FLT3i therapy. Here, we systematically investigated acute cellular responses to on-target therapy with multiple FLT3i in FLT3-ITD + AML using recently developed functional translatome proteomics (measuring changes in the nascent proteome) with phosphoproteomics. This pinpointed AKT-mTORC1-ULK1-dependent autophagy as a dominant resistance mechanism to on-target FLT3i therapy. FLT3i induced autophagy in a concentration- and time-dependent manner specifically in FLT3-ITD + cells in vitro and in primary human AML cells ex vivo. Pharmacological or genetic inhibition of autophagy increased the sensitivity to FLT3-targeted therapy in cell lines, patient-derived xenografts and primary AML cells ex vivo. In mice xenografted with FLT3-ITD + AML cells, co-treatment with oral FLT3 and autophagy inhibitors synergistically impaired leukemia progression and extended overall survival. Our findings identify a molecular mechanism responsible for primary FLT3i treatment resistance and demonstrate the pre-clinical efficacy of a rational combination treatment strategy targeting both FLT3 and autophagy induction.

Metabolic Rewiring Is Essential for AML Cell Survival to Overcome Autophagy Inhibition by Loss of ATG3.

Autophagy is an important survival mechanism that allows recycling of nutrients and removal of damaged organelles and has been shown to contribute to the proliferation of acute myeloid leukemia (AML) cells. However, little is known about the mechanism by which autophagy- dependent AML cells can overcome dysfunctional autophagy. In our study we identified autophagy related protein 3 (ATG3) as a crucial autophagy gene for AML cell proliferation by conducting a CRISPR/Cas9 dropout screen with a library targeting around 200 autophagy-related genes. shRNA-mediated loss of ATG3 impaired autophagy function in AML cells and increased their mitochondrial activity and energy metabolism, as shown by elevated mitochondrial ROS generation and mitochondrial respiration. Using tracer-based NMR metabolomics analysis we further demonstrate that the loss of ATG3 resulted in an upregulation of glycolysis, lactate production, and oxidative phosphorylation. Additionally, loss of ATG3 strongly sensitized AML cells to the inhibition of mitochondrial metabolism. These findings highlight the metabolic vulnerabilities that AML cells acquire from autophagy inhibition and support further exploration of combination therapies targeting autophagy and mitochondrial metabolism in AML.

Colonization with multi-drug-resistant organisms negatively impacts survival in patients with non-small cell lung cancer.

OBJECTIVES: Multidrug-resistant organisms (MDRO) are considered an emerging threat worldwide. Data covering the clinical impact of MDRO colonization in patients with solid malignancies, however, is widely missing. We sought to determine the impact of MDRO colonization in patients who have been diagnosed with Non-small cell lung cancer (NSCLC) who are at known high-risk for invasive infections. MATERIALS AND METHODS: Patients who were screened for MDRO colonization within a 90-day period after NSCLC diagnosis of all stages were included in this single-center retrospective study. RESULTS: Two hundred and ninety-five patients were included of whom 24 patients (8.1%) were screened positive for MDRO colonization (MDROpos) at first diagnosis. Enterobacterales were by far the most frequent MDRO detected with a proportion of 79.2% (19/24). MDRO colonization was present across all disease stages and more present in patients with concomitant diabetes mellitus. Median overall survival was significantly inferior in the MDROpos study group with a median OS of 7.8 months (95% CI, 0.0-19.9 months) compared to a median OS of 23.9 months (95% CI, 17.6-30.1 months) in the MDROneg group in univariate (p = 0.036) and multivariate analysis (P = 0.02). Exploratory analyses suggest a higher rate of non-cancer-related-mortality in MDROpos patients compared to MDROneg patients (p = 0.002) with an increased rate of fatal infections in MDROpos patients (p = 0.0002). CONCLUSIONS: MDRO colonization is an independent risk factor for inferior OS in patients diagnosed with NSCLC due to a higher rate of fatal infections. Empirical antibiotic treatment approaches should cover formerly detected MDR commensals in cases of (suspected) invasive infections.

Activation of Epidermal Growth Factor Receptor Sensitizes Glioblastoma Cells to Hypoxia-Induced Cell Death.

BACKGROUND: The epidermal growth factor receptor (EGFR) signaling pathway is genetically activated in approximately 50% of glioblastomas (GBs). Its inhibition has been explored clinically but produced disappointing results, potentially due to metabolic effects that protect GB cells against nutrient deprivation and hypoxia. Here, we hypothesized that EGFR activation could disable metabolic adaptation and define a GB cell population sensitive to starvation. METHODS: Using genetically engineered GB cells to model different types of EGFR activation, we analyzed changes in metabolism and cell survival under conditions of the tumor microenvironment. RESULTS: We found that expression of mutant EGFRvIII as well as EGF stimulation of EGFR-overexpressing cells impaired physiological adaptation to starvation and rendered cells sensitive to hypoxia-induced cell death. This was preceded by adenosine triphosphate (ATP) depletion and an increase in glycolysis. Furthermore, EGFRvIII mutant cells had higher levels of mitochondrial superoxides potentially due to decreased metabolic flux into the serine synthesis pathway which was associated with a decrease in the NADPH/NADP+ ratio. CONCLUSIONS: The finding that EGFR activation renders GB cells susceptible to starvation could help to identify a subgroup of patients more likely to benefit from starvation-inducing therapies.

Low-dose melphalan in elderly patients with relapsed or refractory acute myeloid leukemia: A well-tolerated and effective treatment after hypomethylating-agent failure.

Relapsed or refractory (R/R) disease remains challenging in acute myeloid leukemia (AML), especially in elderly patients not considered eligible for intensive treatment options. We retrospectively evaluated the safety and efficacy of low-dose melphalan (LD-Mel) in a multicenter analysis in patients over 65 years with R/R AML, who previously had received ≥1 non-curative treatment line. The study included 31 patients (median age 77 years) with 1-4 previous treatment lines. Three patients (9.7%) achieved a complete remission. Two patients (6.5%) achieved a partial remission, nine patients (29.0%) had disease stabilization with reduction of peripheral or bone marrow blast burden, resulting in an overall response rate of 16.1% and 45.2% achieved clinical benefit. Responders showed a significantly longer median overall survival than non-responders (16.3 vs. 2.3 months, p < 0.001). Multivariate analysis identified complex karyotype as the only risk factor associated with inferior survival (p < 0.001), whereas prior treatment with hypomethylating agents (HMAs) in 25 of 31 patients was associated with superior OS, regardless of prior response to HMAs (p = 0.03). LD-Mel was well tolerated, with mild myelosuppressive side effects. Conclusively, LD-Mel is an effective treatment option in elderly patients with R/R AML, particularly after HMA therapy and in the absence of a complex karyotype.

Conservation of structure, function and inhibitor binding in UNC-51-like kinase 1 and 2 (ULK1/2).

Autophagy is essential for cellular homeostasis and when deregulated this survival mechanism has been associated with disease development. Inhibition of autophagy initiation by inhibiting the kinase ULK1 (Unc-51-like autophagy activating kinase 1) has been proposed as a potential cancer therapy. While inhibitors and crystal structures of ULK1 have been reported, little is known about the other closely related kinase ULK2 (Unc-51-like autophagy activating kinase 2). Here, we present the crystal structure of ULK2 in complex with ATP competitive inhibitors. Surprisingly, the ULK2 structure revealed a dimeric assembly reminiscent of dimeric arrangements of auto-activating kinases suggesting a role for this association in ULK activation. Screening of a kinase focused library of pre-clinical and clinical compounds revealed several potent ULK1/2 inhibitors and good correlation of inhibitor-binding behavior with both ULK kinases. Aurora A was identified as a major off-target of currently used ULK1 inhibitors. Autophagic flux assays demonstrated that this off-target activity by strongly inducing autophagy in different cellular systems conferred an additional layer of complexity in the interpretation of cellular data. The data presented here provide structural models and chemical starting points for the development of ULK1/2 dual inhibitors with improved selectivity for future exploitation of autophagy inhibition.

Loss of the selective autophagy receptor p62 impairs murine myeloid leukemia progression and mitophagy.

Autophagy maintains hematopoietic stem cell integrity and prevents malignant transformation. In addition to bulk degradation, selective autophagy serves as an intracellular quality control mechanism and requires autophagy receptors, such as p62 (SQSTM1), to specifically bridge the ubiquitinated cargos into autophagosomes. Here, we investigated the function of p62 in acute myeloid leukemia (AML) in vitro and in murine in vivo models of AML. Loss of p62 impaired expansion and colony-forming ability of leukemia cells and prolonged latency of leukemia development in mice. High p62 expression was associated with poor prognosis in human AML. Using quantitative mass spectrometry, we identified enrichment of mitochondrial proteins upon immunoprecipitation of p62. Loss of p62 significantly delayed removal of dysfunctional mitochondria, increased mitochondrial superoxide levels, and impaired mitochondrial respiration. Moreover, we demonstrated that the autophagy-dependent function of p62 is essential for cell growth and effective mitochondrial degradation by mitophagy. Our results highlight the prominent role of selective autophagy in leukemia progression, and specifically, the importance of mitophagy to maintain mitochondrial integrity.

Survey and analysis of the efficacy and prescription pattern of sorafenib in patients with acute myeloid leukemia.

Sorafenib is a multi-kinase inhibitor with activity against several intracellular kinases which may play a role in the pathogenesis of acute myeloid leukemia (AML). In vitro data and results from early clinical trials suggest that sorafenib might be an effective drug for the treatment of AML. However, clinical data are still sparse, and there are only a few reported cases of monotherapy. The aim of the present research was to collect clinical data on efficacy and safety in a systematic way by conducting a survey on clinical experience with sorafenib. Thirty institutions were asked to document all patients treated with sorafenib diagnosed with AML. Of all 29 evaluable patients, six (21%) responded to sorafenib containing treatment by achieving a complete remission (CR, n = 2) or complete remission with incomplete platelet recovery (CRi, n = 4). In 23 patients receiving sorafenib as monotherapy, the CRi rate amounted to 13% and no CRs were documented. Of the 18 FLT-ITD positive patients with sorafenib monotherapy, two patients achieved a CRi (11%). In five FLT3-ITD negative cases, one CRi was documented (20%). Our results suggest the potential ability of the drug to induce remissions in refractory or relapsed AML even when given as monotherapy.

Pore-forming Staphylococcus aureus alpha-toxin triggers epidermal growth factor receptor-dependent proliferation.

Staphylococcal alpha-toxin is an archetypal killer protein that homo-oligomerizes in target cells to create small transmembrane pores. The membrane-perforating beta-barrel motif is a conserved attack element of cytolysins of Gram-positive and Gram-negative bacteria. Following the recognition that nucleated cells can survive membrane permeabilization, a profile of abundant transcripts was obtained in transiently perforated keratinocytes. Several immediate early genes were found to be upregulated, reminiscent of the cellular response to growth factors. Cell cycle analyses revealed doubling of S + G2/M phase cells 26 h post toxin treatment. Determination of cell counts uncovered that after an initial drop, numbers increased to exceed the controls after 2 days. A non-lytic alpha-toxin mutant remained without effect. The alpha-toxin pore is too small to allow egress of cytosolic growth factors, and evidence was instead obtained for growth signalling via the epidermal growth factor receptor (EGFR). Inhibition of the EGFR or of EGFR-proligand-processing blocked the mitogenic effect of alpha-toxin. Western blots with phospho-specific antibodies revealed activation of the EGFR, and of the adapter protein Shc. Immediate early response and proliferation upon transient plasma membrane pore formation by bacterial toxins may represent a novel facet of the complex interaction between pathogen and host.