Venetoclax therapy and emerging resistance mechanisms in acute myeloid leukaemia.

Acute myeloid leukaemia (AML) is a highly aggressive and devastating malignancy of the bone marrow and blood. For decades, intensive chemotherapy has been the frontline treatment for AML but has yielded only poor patient outcomes as exemplified by a 5-year survival rate of < 30%, even in younger adults. As knowledge of the molecular underpinnings of AML has advanced, so too has the development new strategies with potential to improve the treatment of AML patients. To date the most promising of these targeted agents is the BH3-mimetic venetoclax which in combination with standard of care therapies, has manageable non-haematological toxicity and exhibits impressive efficacy. However, approximately 30% of AML patients fail to respond to venetoclax-based regimens and almost all treatment responders eventually relapse. Here, we review the emerging mechanisms of intrinsic and acquired venetoclax resistance in AML and highlight recent efforts to identify novel strategies to overcome resistance to venetoclax.

Use of Dulaglutide, Semaglutide, and Tirzepatide in Diabetes and Weight Management.

PURPOSE: Glucagon-like peptide 1 receptor agonists (GLP1-RA) are effective therapies in lowering glycosylated hemoglobin (HbA1c), providing cardioprotective benefits, and lowering weight. The use of GLP1-RA solely for weight-loss has become commonplace in many practices, which in turn has made it difficult in some areas for those with type 2 diabetes (T2DM) to obtain these much-needed medications. METHODS: Using recent published literature, along with clinical experience, it has become apparent that many GLP1-RAs have become difficult to obtain for patients with diabetes. FINDINGS: Many clinicians started to prescribe the brand Ozempic® (semaglutide*) and dulaglutide for weight loss despite neither of them being Food and Drug Administration (FDA) approved for this indication. Ozempic, having outperformed dulaglutide in in both HbA1c reduction and weight loss, along with FDA approval of semaglutide for weight loss, has quickly become widely used off-label for weight loss. This off-label use may have increased, despite the approval of semaglutide,† because many insurances will not cover semaglutide solely for weight management. Most recently, Eli Lilly was able to develop tirzepatide,‡ which was FDA approved in May of 2022, and they are seeking fast-track FDA approval for weight loss and are projected to gain this approval within 2023. IMPLICATIONS: Insurance coverage for weight management remains sparse, and obtaining these therapies for diabetes has now become more burdensome, with insurance companies requiring a prior authorization proving FDA-approved diagnosis of T2DM. Hopefully, should more GLP1-Ras receive approval for weight loss, along with an increase in insurance coverage, the burden on patients with diabetes will be lessened as they are able to quickly obtain this highly effective therapy.

Partnering for Better Health: Using Continuous Glucose Monitoring and Clinical Pharmacist Collaboration to Improve Glycemic Control in Underserved Patients With Type 2 Diabetes.

PURPOSE: The purpose of this study was to examine the effect of initiating use of a continuous glucose monitor (CGM) in patients being treated for type 2 diabetes mellitus, specifically those who face barriers to obtaining this device because of its cost. METHODS: This retrospective medical record review compared diabetes control of patients before and after use of a CGM device within a single primary care office. Patient medical records were reviewed 18 months after initial CGM was provided, and only those who received a CGM directly from the clinic were included in the review. Statistical analysis comparing the difference in mean baseline glycosylated hemoglobin (HbA1c) level with the first HbA1c level after CGM placement was completed using the paired t test for the primary outcome. FINDINGS: A total of 41 patients who obtained at least 1 CGM reader and a minimum of a 30-day supply of sensors from the clinic were included in the review. The primary outcome resulted in a significant reduction in the mean (SD) first HbA1c level after CGM placements of -1.9% (2.5%) (P < .001) with a total of 10 and 22 patients with an HbA1c level <7% and 8%, respectively. This mean (SD) reduction in HbA1c level was also seen in both insulin-treated patients (-1.8% [2.8%], n = 30) and non-insulin-treated patients (-2% [2.8%], n=11). The largest reduction in the first HbA1c level after CGM placement was seen in those patients provided a CGM along with collaborative care with a clinical pharmacist. These patients saw a mean (SD) decrease of -2.5% [2.7%] (n = 26) in their HbA1c level with a mean (SD) decrease of -0.8% (1.6%) (n = 15) for those not comanaged by the clinical pharmacist. IMPLICATIONS: The results of this study suggest that the use of CGM in the underserved population can lead to a significant improvement in glycemic control in patients with diabetes, regardless of treatment therapies used. Involving a multidisciplinary team in diabetes management, including clinical pharmacists, may further improve outcomes. Access to these devices in the underserved population may be crucial in reducing the risk of developing complications related to uncontrolled diabetes.

An orthotopic syngeneic mouse model of bortezomib-resistant multiple myeloma.

While bortezomib has significant benefits in multiple myeloma (MM) therapy, the disease remains incurable due to the invariable development of bortezomib resistance. This emphasises the need for advanced models for preclinical evaluation of new therapeutic approaches for bortezomib-resistant MM. Here, we describe the development of an orthotopic syngeneic bortezomib-resistant MM mouse model based on the most well-characterised syngeneic MM mouse model derived from spontaneous MM-forming C57BL/KaLwRij mice. Using bortezomib-resistant 5TGM1 cells, we report and characterise a robust syngeneic mouse model of bortezomib-resistant MM that is well suited to the evaluation of new therapeutic approaches for proteasome inhibitor-resistant MM.

A systematic review of antimicrobial therapy in children with tracheostomies.

Tracheostomies are indicated in children to facilitate long-term ventilatory support, aid in the management of secretions, or manage upper airway obstruction. Children with tracheostomies often experience ongoing airway complications, of which respiratory tract infections are common. They subsequently receive frequent courses of broad-spectrum antimicrobials for the prevention or treatment of respiratory tract infections. However, there is little consensus in practice with regard to the indication for treatment/prophylactic antimicrobial use, choice of antimicrobial, route of administration, or duration of treatment between different centers. Routine antibiotic use is associated with adverse effects and an increased risk of antimicrobial resistance. Tracheal cultures are commonly obtained from pediatric tracheostomy patients, with the aim of helping guide antimicrobial therapy choice. However, a positive culture alone is not diagnostic of infection and the role of routine surveillance cultures remains contentious. Inhaled antimicrobial use is also widespread in the management of tracheostomy-associated infections; this is largely based on the theoretical benefits of higher airway antibiotic concentrations. The role of prophylactic inhaled antimicrobial use for tracheostomy-associated infections remains largely unproven. This systematic review summarizes the current evidence base for antimicrobial selection, duration, and administration route in pediatric tracheostomy-associated infections. It also highlights significant variation in practice between centers and the urgent need for further prospective evidence to guide the management of these vulnerable patients.

Genome-wide transcription factor-binding maps reveal cell-specific changes in the regulatory architecture of human HSPCs.

Hematopoietic stem and progenitor cells (HSPCs) rely on a complex interplay among transcription factors (TFs) to regulate differentiation into mature blood cells. A heptad of TFs (FLI1, ERG, GATA2, RUNX1, TAL1, LYL1, LMO2) bind regulatory elements in bulk CD34+ HSPCs. However, whether specific heptad-TF combinations have distinct roles in regulating hematopoietic differentiation remains unknown. We mapped genome-wide chromatin contacts (HiC, H3K27ac, HiChIP), chromatin modifications (H3K4me3, H3K27ac, H3K27me3) and 10 TF binding profiles (heptad, PU.1, CTCF, STAG2) in HSPC subsets (stem/multipotent progenitors plus common myeloid, granulocyte macrophage, and megakaryocyte erythrocyte progenitors) and found TF occupancy and enhancer-promoter interactions varied significantly across cell types and were associated with cell-type-specific gene expression. Distinct regulatory elements were enriched with specific heptad-TF combinations, including stem-cell-specific elements with ERG, and myeloid- and erythroid-specific elements with combinations of FLI1, RUNX1, GATA2, TAL1, LYL1, and LMO2. Furthermore, heptad-occupied regions in HSPCs were subsequently bound by lineage-defining TFs, including PU.1 and GATA1, suggesting that heptad factors may prime regulatory elements for use in mature cell types. We also found that enhancers with cell-type-specific heptad occupancy shared a common grammar with respect to TF binding motifs, suggesting that combinatorial binding of TF complexes was at least partially regulated by features encoded in DNA sequence motifs. Taken together, this study comprehensively characterizes the gene regulatory landscape in rare subpopulations of human HSPCs. The accompanying data sets should serve as a valuable resource for understanding adult hematopoiesis and a framework for analyzing aberrant regulatory networks in leukemic cells.

Circular RNAs drive oncogenic chromosomal translocations within the MLL recombinome in leukemia.

The first step of oncogenesis is the acquisition of a repertoire of genetic mutations to initiate and sustain the malignancy. An important example of this initiation phase in acute leukemias is the formation of a potent oncogene by chromosomal translocations between the mixed lineage leukemia (MLL) gene and one of 100 translocation partners, known as the MLL recombinome. Here, we show that circular RNAs (circRNAs)-a family of covalently closed, alternatively spliced RNA molecules-are enriched within the MLL recombinome and can bind DNA, forming circRNA:DNA hybrids (circR loops) at their cognate loci. These circR loops promote transcriptional pausing, proteasome inhibition, chromatin re-organization, and DNA breakage. Importantly, overexpressing circRNAs in mouse leukemia xenograft models results in co-localization of genomic loci, de novo generation of clinically relevant chromosomal translocations mimicking the MLL recombinome, and hastening of disease onset. Our findings provide fundamental insight into the acquisition of chromosomal translocations by endogenous RNA carcinogens in leukemia.

Idiopathic subglottic stenosis arises at the epithelial interface of host and pathogen.

Background: Idiopathic subglottic stenosis (iSGS) is a rare fibrotic disease of the proximal airway affecting adult Caucasian women nearly exclusively. Life-threatening ventilatory obstruction occurs secondary to pernicious subglottic mucosal scar. Disease rarity and wide geographic patient distribution has previously limited substantive mechanistic investigation into iSGS pathogenesis. Result: By harnessing pathogenic mucosa from an international iSGS patient cohort and single-cell RNA sequencing, we unbiasedly characterize the cell subsets in the proximal airway scar and detail their molecular phenotypes. Results show that the airway epithelium in iSGS patients is depleted of basal progenitor cells, and the residual epithelial cells acquire a mesenchymal phenotype. Observed displacement of bacteria beneath the lamina propria provides functional support for the molecular evidence of epithelial dysfunction. Matched tissue microbiomes support displacement of the native microbiome into the lamina propria of iSGS patients rather than disrupted bacterial community structure. However, animal models confirm that bacteria are necessary for pathologic proximal airway fibrosis and suggest an equally essential role for host adaptive immunity. Human samples from iSGS airway scar demonstrate adaptive immune activation in response to the proximal airway microbiome of both matched iSGS patients and healthy controls. Clinical outcome data from iSGS patients suggests surgical extirpation of airway scar and reconstitution with unaffected tracheal mucosa halts the progressive fibrosis. Conclusion: Our data support an iSGS disease model where epithelial alterations facilitate microbiome displacement, dysregulated immune activation, and localized fibrosis. These results refine our understanding of iSGS and implicate shared pathogenic mechanisms with distal airway fibrotic diseases.

Tracheostomy in children is associated with neutrophilic airway inflammation.

BACKGROUND: Tracheostomies in children are associated with significant morbidity, poor quality of life, excess healthcare costs and excess mortality. The underlying mechanisms facilitating adverse respiratory outcomes in tracheostomised children are poorly understood. We aimed to characterise airway host defence in tracheostomised children using serial molecular analyses. METHODS: Tracheal aspirates, tracheal cytology brushings and nasal swabs were prospectively collected from children with a tracheostomy and controls. Transcriptomic, proteomic and metabolomic methods were applied to characterise the impact of tracheostomy on host immune response and the airway microbiome. RESULTS: Children followed up serially from the time of tracheostomy up to 3 months postprocedure (n=9) were studied. A further cohort of children with a long-term tracheostomy were also enrolled (n=24). Controls (n=13) comprised children without a tracheostomy undergoing bronchoscopy. Long-term tracheostomy was associated with airway neutrophilic inflammation, superoxide production and evidence of proteolysis when compared with controls. Reduced airway microbial diversity was established pre-tracheostomy and sustained thereafter. CONCLUSIONS: Long-term childhood tracheostomy is associated with a inflammatory tracheal phenotype characterised by neutrophilic inflammation and the ongoing presence of potential respiratory pathogens. These findings suggest neutrophil recruitment and activation as potential exploratory targets in seeking to prevent recurrent airway complications in this vulnerable group of patients.

Providing care for children with tracheostomies: a qualitative interview study with parents and health professionals.

OBJECTIVES: To explore the experience of caring for children with tracheostomies from the perspectives of parents and health professional caregivers. DESIGN: Qualitative semistructured interview study. SETTING: One region in England covered by a tertiary care centre that includes urban and remote rural areas and has a high level of deprivation. PARTICIPANTS: A purposive sample of health professionals and parents who care for children who have, or have had, tracheostomies and who received care at the tertiary care centre. INTERVENTION: Interviews undertaken by telephone or video link. PRIMARY AND SECONDARY OUTCOME MEASURES: Qualitative reflexive thematic analysis with QSR Nvivo 12. RESULTS: This paper outlines key determinants and mediators of the experiences of caregiving and the impact on psychological and physical health and quality of life of parents and their families, confidence of healthcare providers and perceived quality of care. For parents, access to care packages and respite care at home as well as communication and relationships with healthcare providers are key mediators of their experience of caregiving, whereas for health professionals, an essential influence is multidisciplinary team working and support. We also highlight a range of challenges focused on the shared care space, including: a lack of standardisation in access to different support teams, care packages and respite care, irregular training and updates, and differences in health provider expertise and experiences across departments and shift patterns, exacerbated in some settings by limited contact with children with tracheostomies. CONCLUSIONS: Understanding the experiences of caregiving can help inform measures to support caregivers and improve quality standards. Our findings suggest there is a need to facilitate further standardisation of care and support available for parent caregivers and that this may be transferable to other regions. Potential solutions to be explored could include the development of a paediatric tracheostomy service specification, increasing use of paediatric tracheostomy specialist nurse roles, and addressing the emotional and psychological support needs of caregivers.

The utility of a symptom model to predict the risk of oesophageal cancer.

OBJECTIVE: To assess whether extra-oesophageal symptoms are predictive of oesophageal malignancy. METHODS: A prospective, single-centre cross-sectional questionnaire study at a tertiary referral unit for oesophageal cancer using the Comprehensive Reflux Symptoms Scale (CReSS) questionnaire tool. Respondents with oesophageal malignancy were compared with historical cohorts undergoing airway examination or upper gastrointestinal endoscopy and found to have benign diagnoses. We developed a model for predicting oesophageal cancer using linear discriminant analysis and logistic regression, assessed by Monte Carlo cross validation. RESULTS: Respondents with oesophageal malignancy (n = 146; mean age 70.5; male: female, 71:29) were compared with those undergoing airway examination (n = 177) and upper gastrointestinal endoscopy (n = 351), found to have benign diagnoses. No single questionnaire item, or group of co-varying items (factors), reliably discriminated oesophageal cancer from other diagnoses. Individual items which suggested higher risk of oesophageal malignancy included dysphagia (area under the curve (AUC) 0.68), low appetite (AUC 0.66), and early satiety (AUC 0.58). Conversely, throat pain (AUC 0.38), bloating (AUC 0.38) and heartburn (AUC 0.37) were inversely related to cancer risk. A forward stepwise regression analysis including a subset of 12 CReSS questionnaire items together with age and sex derived a model predictive of oesophageal malignancy in this cohort (AUC 0.89). CONCLUSION: We demonstrate a model comprised of 12 questionnaire items and 2 demographic parameters as a potential predictive tool for oesophageal malignancy diagnosis in this study population. Translating this model for predicting oesophageal malignancy in the general population is a valuable topic for future research.

Targeting the integrated stress response in hematologic malignancies.

While numerous targeted therapies have been recently adopted to improve the treatment of hematologic malignancies, acquired or intrinsic resistance poses a significant obstacle to their efficacy. Thus, there is increasing need to identify novel, targetable pathways to further improve therapy for these diseases. The integrated stress response is a signaling pathway activated in cancer cells in response to both dysregulated growth and metabolism, and also following exposure to many therapies that appears one such targetable pathway for improved treatment of these diseases. In this review, we discuss the role of the integrated stress response in the biology of hematologic malignancies, its critical involvement in the mechanism of action of targeted therapies, and as a target for pharmacologic modulation as a novel strategy for the treatment of hematologic malignancies.

A human model of bilateral pulmonary vein sampling to assess the effects of one-lung ventilation on neutrophil function.

BACKGROUND: Neutrophil activation drives lung complications after cardiopulmonary bypass (CPB). Evidence suggests the healthy, ventilated lung may beneficially re-condition pro-inflammatory neutrophils. However, evidence in humans is lacking, due to a paucity of good models. CPB with simultaneous central venous and bilateral pulmonary vein sampling provides an opportunity to model effects of one-lung ventilation. The study's primary objectives were to establish a model of intra-operative, bilateral pulmonary vein sampling and to determine whether neutrophil function differed after passing through inflated or deflated lungs. METHODS: Seventeen patients having "on pump" coronary artery bypass grafting (CABG) with one-lung ventilation (in two cohorts with tidal volume 2ml kg-1 and FiO2 0.21, or tidal volume 4 ml kg-1 and FiO2 0.5 respectively) were recruited. Cohort 1 consisted of 9 patients (7 male, median age 62.0 years) and Cohort 2 consisted of 8 male patients (median age 65.5 years). Recruitment was via prospective screening of scheduled elective and non-elective CABG procedures with cardiopulmonary bypass. Each patient had five blood samples taken-central venous blood pre-operatively; central venous blood pre-CPB; central venous blood post-CPB; pulmonary venous blood draining the ventilated lung post-CPB; and pulmonary venous blood draining the deflated lung post-CPB. Neutrophil phagocytosis and priming status were quantified. Plasma cytokines were measured. RESULTS: Phagocytosis and priming were not significantly different in neutrophils returning from the ventilated lung as compared to the non-ventilated lung. Plasma IL-6, IL-8 and IL-10 were significantly elevated by CPB. CONCLUSIONS: The intra-operative, bilateral pulmonary vein sampling model provides unique opportunities to assess biological effects of interventions to one lung, with the other lung acting as an internal control. Single-lung ventilation during CPB had no significant effects on neutrophil function.

Clinical Reasoning: A 65-Year-Old Woman With Cancer History and Wrist Drop.

Wrist drop is a common presentation in neurology. To localize the lesion, clinicians can focus on testing finger extension, elbow flexion with semipronated forearm, and elbow extension among other muscle groups and identifying dermatomes of numbness. Once the lesion is localized, electrophysiology or imaging can guide to an underlying etiology. Here, we describe a case that illustrates the importance of using a stepwise approach to diagnose the etiology of wrist drop in a patient with a cancer history. A 65-year-old woman with diffuse large B-cell lymphoma in remission presented with new onset wrist drop, severe pain, numbness, and tingling concerning for peripheral nerve injury. Imaging findings from PET, venous ultrasound, nerve conduction velocity study, and MRI were conflicting favoring deep venous thrombosis, cancer recurrence, or peripheral nerve sheath tumor. A biopsy was ultimately required to confirm the diagnosis.

Germline mutations in mitochondrial complex I reveal genetic and targetable vulnerability in IDH1-mutant acute myeloid leukaemia.

The interaction of germline variation and somatic cancer driver mutations is under-investigated. Here we describe the genomic mitochondrial landscape in adult acute myeloid leukaemia (AML) and show that rare variants affecting the nuclear- and mitochondrially-encoded complex I genes show near-mutual exclusivity with somatic driver mutations affecting isocitrate dehydrogenase 1 (IDH1), but not IDH2 suggesting a unique epistatic relationship. Whereas AML cells with rare complex I variants or mutations in IDH1 or IDH2 all display attenuated mitochondrial respiration, heightened sensitivity to complex I inhibitors including the clinical-grade inhibitor, IACS-010759, is observed only for IDH1-mutant AML. Furthermore, IDH1 mutant blasts that are resistant to the IDH1-mutant inhibitor, ivosidenib, retain sensitivity to complex I inhibition. We propose that the IDH1 mutation limits the flexibility for citrate utilization in the presence of impaired complex I activity to a degree that is not apparent in IDH2 mutant cells, exposing a mutation-specific metabolic vulnerability. This reduced metabolic plasticity explains the epistatic relationship between the germline complex I variants and oncogenic IDH1 mutation underscoring the utility of genomic data in revealing metabolic vulnerabilities with implications for therapy.

Ceramide-induced integrated stress response overcomes Bcl-2 inhibitor resistance in acute myeloid leukemia.

Inducing cell death by the sphingolipid ceramide is a potential anticancer strategy, but the underlying mechanisms remain poorly defined. In this study, triggering an accumulation of ceramide in acute myeloid leukemia (AML) cells by inhibition of sphingosine kinase induced an apoptotic integrated stress response (ISR) through protein kinase R-mediated activation of the master transcription factor ATF4. This effect led to transcription of the BH3-only protein Noxa and degradation of the prosurvival Mcl-1 protein on which AML cells are highly dependent for survival. Targeting this novel ISR pathway, in combination with the Bcl-2 inhibitor venetoclax, synergistically killed primary AML blasts, including those with venetoclax-resistant mutations, as well as immunophenotypic leukemic stem cells, and reduced leukemic engraftment in patient-derived AML xenografts. Collectively, these findings provide mechanistic insight into the anticancer effects of ceramide and preclinical evidence for new approaches to augment Bcl-2 inhibition in the therapy of AML and other cancers with high Mcl-1 dependency.