John D. Dingell VA Medical Center

BackgroundObstructive sleep apnea (OSA) pathogenesis, clinical manifestations, and consequences vary markedly among patients. Yet OSA heterogeneity goes largely unaddressed in current management pathways, which are characterized by high treatment failure rates of ∼50%. Growing knowledge of OSA pathogenesis has stimulated new lines of investigation for therapies targeted to specific underlying mechanisms or “endotypes.” OSA endotypes include the primary anatomic predisposition to pharyngeal collapse, as well as “nonanatomic” mechanisms of low arousal threshold, unstable control of breathing (high loop gain), and impaired pharyngeal dilator muscle function. Identification of interindividual differences in OSA endotypes and disease expression, or “OSA phenotypes,” offers promise for a more targeted approach to OSA management in which appropriate treatments are tailored to individual needs. However, these concepts have largely been limited to the research setting, and more evidence is needed to support clinical translation.GoalsTo outline the rationale for clinical use, challenges, and key research priorities required to translate OSA endophenotyping for delivery of a more tailored approach to improve patient care and outcomes.MethodsAn international multidisciplinary working group with expertise in OSA epidemiology, pathophysiology, diagnostics, and treatments was convened. The group met at the American Thoracic Society 2024 International Conference to discuss the current state of OSA endophenotyping and required research objectives. This research statement, authored with input from all members, summarizes the group discussion, identified key areas, and research priorities.ResultsThe working group identified research priorities that cover the spectrum from discovery to translation/implementation, including technical standards, validation, establishment of clinical cutoffs and minimal clinically important differences, generalizability across diverse populations, stability and reproducibility of measurement, prospective study design and conduct, clinical utility, and impact analysis.ConclusionsThis research statement provides a road map of the opportunities and key steps required to generate the evidence necessary to translate OSA endophenotyping concepts into clinical care at scale.

Persons with spinal cord injuries often suffer from autonomic dysfunction, sleep disordered breathing, and impaired mitochondrial capacity. Current treatment options for these individuals are limited and often have significant side effects. Thus, new interventions that target multiple physiological systems and circumvent physical limitations would be a significant development for persons with spinal cord injury (pwSCI). One potential intervention is daily mild intermittent hypoxia (MIH) which has been shown to improve blood pressure control and upper airway function during sleep. Four individuals with chronic motor incomplete SCI underwent 8 days of MIH (ClinicalTrials.Gov ID #NCT05351827, https://clinicaltrials.gov/study/NCT05351827). The MIH protocol was administered each morning during wakefulness with end-tidal oxygen maintained at 55–60 mmHg. End-tidal carbon dioxide was maintained at + 3 mmHg above baseline during the MIH. Autonomic dysfunction (autonomic dysreflexia and orthostatic hypotension), sleep quality, upper airway function, mitochondrial capacity, and microvascular function were tested before, the day after, and 2 weeks following the MIH protocol. Systolic autonomic dysreflexia improved by 46% ± 14% and orthostatic hypotension improved by 160% ± 63% after MIH. Reductions in the apnea hypopnea index were observed, alongside a concurrent reduction in arousals during sleep. Upper airway function improved and mitochondrial capacity increased following 8 days of MIH. These preliminary data from four participants in an ongoing clinical trial suggest that 8 days of MIH may improve autonomic dysfunction, sleep quality, and mitochondrial capacity in pwSCI. The recruitment of additional participants is required to support these preliminary findings.Clinical trial registrationhttps://clinicaltrials.gov/study/NCT05351827, identifier NCT05351827.

Background/Aims:Post-translational prenylation of G proteins is implicated in physiological insulin secretion. It has been reported recently that GGTase-III participates in the functional regulation of Ykt6, a synaptobrevin homolog, via geranylgeranylation. However, potential localization and putative regulatory roles of GGTase-III in insulin secretion remains unknown. The current study is aimed at determining the expression and contributory roles of GGTase-III in glucose- and KCl-induced insulin secretion from pancreatic β-cells.Methods:Mouse islets were isolated by the collagenase digestion method. Human islets were from Prodo Laboratories. INS-1 832/13 cells were transfected with either control (scrambled) or siRNA-PTAR1 (the α-subunit of GGTase-III) using lipofectamine RNAiMax. Insulin released into the medium was quantified using a commercially available Insulin ELISA kit. Expression of GGTase-III subunits and ykt6 was determined by Western blotting and quantified by densitometry.Results:Western blotting revealed that both subunits of GGTase-III (PTAR1 and RabGGTB) are expressed in human islets, mouse islets and INS-1 832/13 cells. Transfection of INS-1 832/13 cells with siRNA-PTAR1 resulted in significant reduction (~50%) in the expression of PTAR1. siRNA-mediated knockdown of PTAR1 significantly attenuated (~60%) glucose-stimulated insulin secretion (GSIS) in INS-1 832/13 cells. Furthermore, insulin secretion elicited via KCl-induced membrane depolarization was markedly reduced (~69%) in INS-1 832/13 cells following PTAR1 depletion. Lastly, immunoblotting data suggested expression of Ykt6, a known substrate for GGTase-III, in human islets, rodent islets, and INS-1 832/13 cells.Conclusion:A GGTase-III-dependent signaling step is necessary for glucose- and KCl-induced insulin secretion.

Carbapenem-resistant Enterobacterales (CRE) and Pseudomonas aeruginosa (CR-PA) continue to pose a significant threat to human health. Furthermore, the prevalence of metallo-β-lactamase (MBL)-producing CRE and CR-PA is increasing, which are capable of hydrolyzing nearly all β-lactam antibiotics. Cefepime-taniborbactam (FTB) is a novel bicyclic boronate β-lactam-β-lactamase inhibitor combination with direct inhibitory activity against MBLs (Ambler Class B), in addition to Ambler Class A, C, and D serine-β-lactamases. FTB has demonstrated high invitro activity against CRE and CR-PA, including isolates producing NDM, VIM, KPC, AmpC, OXA-48, and extended-spectrum β-lactamases (ESBLs). Furthermore, FTB has demonstrated invitro activity against Stenotrophomonas maltophilia and Burkholderia cepacia complex. Resistance to FTB is observed in isolates producing IMP, as well as MBL variants NDM-9, NDM-30, and VIM-83. FTB remains susceptible to non-β-lactamase resistance mechanisms, including penicillin-binding protein 3 (PBP3) target mutations. The pharmacodynamic driver of taniborbactam efficacy is the ratio of the area under the curve to the minimum inhibitory concentration (AUC/MIC), and the study dose of FTB 2 g/0.5 g every 8 h infused over 2 h achieves sufficient serum and tissue exposures to maintain therapeutic efficacy. Both components are primarily renally eliminated as unchanged drug; therefore, dose adjustments for renal impairment are required. The clinical efficacy of FTB was demonstrated in the phase III Cefepime Rescue with Taniborbactam in Complicated Urinary Tract Infection (CERTAIN-1) trial, where it demonstrated both non-inferiority and superiority (prespecified analysis) to meropenem in the composite of clinical and microbiologic success at the test of cure for the treatment of complicated urinary tract infection. The safety of FTB was demonstrated throughout its clinical development. Thirteen percent of patients experienced a treatment-related adverse drug event in the phase III clinical trial, with 3% of patients requiring discontinuation of the study agent. Cefepime-taniborbactam appears to be a promising addition to the antibiotic arsenal, particularly as the prevalence of infections caused by MBL-producing organisms continues to rise.

Abstract RATIONALE: Central sleep apnea (CSA) is characterized by recurrent cycles of apnea/hypopnea alternating with hyperpnea. Brief arousals following apnea/hypopnea are postulated to perpetuate CSA via hypocapnia below the apneic threshold. METHODS: We hypothesized that apnea or hypopnea would follow hyperventilation due to induced-respiratory arousals. Participants diagnosed with mild to severe sleep-disordered breathing (AHI: 10-64 events per hour) were enrolled. We studied 5 patients with CSA who were otherwise healthy (4 male, 1 female, age: 62-72 years, BMI: 25.6-37.2 kg/m2). During the overnight polysomnography (PSG), participants were initially stabilized with PAP therapy set to the pressure level required to maintain airway patency (holding pressure). We used PAP withdrawal for three breaths to induce upper airway obstruction in patients receiving optimal PAP therapy- with stable sleep, respiration, and oxygenation. RESULTS: Induced respiratory arousal was associated with increased minute ventilation (VE) from 8.1 L/min +/- 5.0 L/min to 19.5 L/min +/- 5.9 L/min (p<0.05). Post-arousal ventilation also showed an increase in VE at 13.9 L/min +/- 4.6 L/min (p<0.05). Nadir ventilation was 94.6% of baseline. Figure 1 displays the change in VE over time marked at each breath. CONCLUSIONS: 1) Induced respiratory arousal resulted in a brief hyperpnea and a return to baseline respiration, but no apnea or hypopnea occurred. 2) Possible explanations include: a) short duration of hyperventilation is insufficient to induce sufficient medullary hypocapnia, b) recurrent events following CSA may be due to an additive effect of hypoxia and arousals, and c) the lack of post-arousal hypopnea may explain the lack effect of suppressing arousals on CSA severity. Figure 1: Change in Minute Ventilation (VE) over Time Marked at Each Breath Values are split into pre-arousal (before pap withdrawal), arousal (on the second line of PAP withdrawal), and post-arousal (after the PAP withdrawal). We see a statistically significant increase (p<0.05) of 11.5 L/min in VE for arousal compared to pre-arousal, as well as for post-arousal breath 1 compared to pre-arousal with an increase of 5.7 L/min (p<0.05). Subsequent post-arousal breath comparisons did not show statistically significant differences compared to pre-arousal.[asterisk]p<0.05

IntroductionRare events data have proven difficult to explain and predict. Standard statistical procedures can sharply underestimate the probability of rare events, such as intravenous immune globulin therapy (IVIg) for bullous pemphigoid.MethodsThis retrospective cross-sectional study used Department of Defense TRICARE data to determine factors associated with IVIg therapy among bullous pemphigoid patients. We used prior and weighted correction methods for logit regression to solve rare event bias.ResultsWe identified 2,720 individuals diagnosed with bullous pemphigoid from 2019 to 2022, of which 14 were treated with IVIg. Patients who received IVIg therapy were younger (65.07 vs. 75.85, P =.0016) and more likely to be female (13 vs. 1, P =.0036). The underestimation with the standard regression model for event probabilities ranged from 11% to 102% using the prior correction method and from 15% to 107% using the weighted correction method.ConclusionRare events are low-frequency, high-severity problems that can have significant consequences. Rare diseases and rare therapies are individually unique but collectively contribute to substantial health and social needs. Therefore, correct estimation of the events is the first step toward assessing the burden of rare diseases and the pricing of their therapies.

Lung cancer remains the most common cancer worldwide, with a limited prognosis despite personalized treatment regimens. Low-dose computed tomography (CT) scanning as a means of early diagnosis has been disappointing due to the high false positive rate. Other non-invasive means of testing need to be developed that offer both timely diagnosis and predict prognosis. Methods: In the course of stool testing in large-scale testing of 2922 patients at increased risk of CRC, we were able to ascertain 112 patients documented to have prospectively been diagnosed with lung cancer. Stool and colonic effluents were tested for p87 with anti-adenoma antibody (Adnab-9) reactivity by ELISA and Western blot. Survival data were obtained where available. Results: Of 112 cancers, approximately 27.6% were squamous (SSC), 17.9% were adenocarcinoma, 8% were small, 6.25% were large cell, 3.57% were designated non-small cell cancer (NSCLC), 0.89% were indeterminate, 0.89% were lepidic spread, 3.57% had metastasis, and in 31.25%, data were unavailable. In total, 49.1% of the lung cancer patients had fecal Adnab-9 testing. Overall, 60% had positive testing compared to 38%, which was significant (OR2.19 [1.06-4.53]; p = 0.045). Cancers with higher lethality were less likely to test positive (approximately 8.5% each for both small and large cell lung cancers) and higher, with 56% for SCC and 25% for adenocarcinoma (0% NSCLC). In the larger groups, overall survival was worse in those testing positive: 474 testing positives versus 844 days in SCC and 54 testing positive versus 749 days in adenocarcinoma patients. Most importantly, the time from a positive test to the clinical diagnosis ranged from 2.72 years for small cell, 3.13 for adenocarcinoma, 5.07 for NSCLC, 6.07 for SSC, and 6.24 for large cell cancer. In excluded cases where cancer in the lung was believed to be metastatic, 83.3% of cancers were positive. Conclusions: At a projected real-world sensitivity of 0.60 and specificity of 0.60, and the ability to predate diagnosis by up to 4.7 years overall, this test could help direct lung cancer screening. In addition, the Adnab-9 testing selectively detects worse tumor types (87.5%) and those with worse prognoses amongst the more common, favorable phenotypes, thus making early diagnosis possible in those patients who stand to benefit most from this strategy. Metastatic lung cancer, also detected by the test, should be identified by the follow-up imaging studies and, therefore, would not be considered to be a major pitfall.

The present study was designed to explore whether the depletion of serotonin (5-HT) in the central nervous system (CNS5-HT) leads to systolic and diastolic dysfunction and whether this dysfunction is exacerbated by sex, age and spinal cord injury. Echocardiographic assessment of systolic and diastolic function was completed in young and old male and female tryptophan hydroxylase 2 knockout (TPH2-/-) and wild-type (TPH2+/+) mice with intact spinal cords, as well as in C2 spinal cord hemisected young TPH2-/- and TPH2+/+ mice. In addition, lumbar sympathetic nervous system activity was recorded in elderly male and female intact TPH2-/- and TPH2+/+ mice. Systolic and diastolic dysfunction was evident in young TPH2-/- mice, including a higher left ventricular mass (P<0.001), left ventricular outflow parameters (e.g. peak velocity) and E/A (P<0.001). Reductions in ejection fraction and fractional shortening were also evident (P<0.001), although stroke volume and cardiac output were maintained. The assessed dysfunction was exacerbated by age and spinal cord injury, resulting in reductions in cardiac output (P≤0.01). The dysfunction was accompanied by increases in sympathetic burst height (P=0.038) and incidence (P=0.001). Reductions in CNS5-HT are coupled to systolic and diastolic dysfunction, which is exacerbated by age and spinal cord injury. This dysfunction is coupled to increases in sympathetic nervous system activity in elderly mice. Our findings are an initial step toward determining whether reductions in CNS5-HT are a unifying mechanism that links central sleep apnoea, sympathoexcitation and heart failure in intact and spinal cord injured individuals. KEY POINTS: Reductions in central nervous system serotonin (CNS5-HT) may contribute to systolic and diastolic dysfunction. This dysfunction may be linked to increases in sympathetic nervous system activity and exacerbated by sex, age and spinal cord injury. Echocardiographic assessment of systolic and diastolic function was completed in young and old male and female intact TPH2+/+ and TPH2-/- mice, as well as in C2spinal cord hemisected young mice. Lumbar sympathetic nervous system activity was also recorded in elderly male and female intact TPH2+/+ and TPH2-/- mice. Systolic and diastolic dysfunction was evident in young TPH2-/- mice. This dysfunction was exacerbated by age and spinal cord injury. The cardiac dysfunction was accompanied by increases in lumbar sympathetic nervous system activity. Our findings are an initial step toward determining whether reductions in CNS5-HT is a unifying mechanism that links central sleep apnoea, sympathoexcitation and heart failure in intact and spinal cord injured individuals.

840 Background: ICIs offer modest response rates (~20%) in mUC and there remains a critical need for validated biomarkers to predict patient benefit. Hyperprogressive disease (HPD), characterized by rapid tumor progression following ICI initiation, is a poorly understood phenomenon in mUC. No robust biomarkers currently exist to identify patients at risk for HPD, a condition that leads to unnecessary treatment and exacerbated toxicity. While patient factors associated with HPD have been studied, little is known about the tumor’s immune-genomic landscape in these cases. We investigate the immune-genomic features of mUC tumors associated with HPD to better understand and predict this response to ICI. Methods: We retrospectively analyzed 132 pts with mUC treated with atezolizumab or pembrolizumab between 2015-2023. All patients received at least 2 ICI cycles, and archival FFPE tumor samples were available for immune-genomic analysis. Pts were classified as responders (N=75, defined as complete/partial response or stable disease) or non-responders (N=57, progressive disease). HPD was defined as progression per RECIST within 14 weeks of ICI initiation. RNA was extracted from macrodissected FFPE samples, and transcriptomic profiling was performed using the Nanostring PanCancer IO 360 panel. Data were processed using nSolver 4.0 and nanostring data analysis service analyzed for differential gene expression. Receiver operator characteristic (ROC) analysis was conducted to assess the predictive power of immune signatures for HPD. Results: Of the 132 pts, 48 (36%) were classified as having HPD. Compared to non-responders without HPD, HPD tumors exhibited significant downregulation of immune signatures, including IFN Gamma, PD-L1, myeloid cells, and tumor inflammation signatures (TIS). Key chemokines and IFN downstream signaling were also downregulated (p-adj = 0.041). Single-gene analysis highlighted downregulation of CCL4 (logFC = -0.947, p = 0.00012), GBP1 (logFC = -0.8105, p = 0.00017), and NECTIN2 (logFC = -0.4792, p = 0.00032) in HPD tumors, though statistical significance was not reached after adjustment. ROC analysis demonstrated modest predictive power for HPD with AUCs of 0.66 for TIS and IFN Gamma, and 0.658 for the immunoproteasome. Conclusions: Our findings reveal a distinct immune-genomic profile in mUC tumors associated with HPD following ICI treatment, including reduced IFN Gamma, TIS, and myeloid cell signaling. These immune signatures may serve as potential biomarkers to identify pts at risk of HPD, warranting further validation in prospective trials. Ongoing analyses will continue to explore the genomic underpinnings of HPD and therapeutic resistance in mUC.