Faculty Bibliography

BACKGROUND:Endovascular aortic aneurysm repair (EVAR) is utilized to treat abdominal aortic aneurysms, while patients with short infrarenal necks can undergo fenestrated EVAR (FEVAR). Previous studies have demonstrated decreased aortic neck dilation for FEVAR compared to EVAR. Sac regression is a marker of success after EVAR; however, little is known regarding changes in sac volumetrics. This study compares aortic sac regression after EVAR versus FEVAR using volumetric analysis. METHODS:A retrospective review of prospectively collected data from 120 patients who underwent EVAR was performed. Thirty patients underwent FEVAR (Cook Medical Inc, Bloomington, IN) and 90 patients underwent EVAR (30 each with Endurant [Medtronic, Dublin, Ireland], Excluder [Gore, Flagstaff, AZ], and Zenith [Cook]). Demographic data were analyzed. Using 3-dimensional reconstruction software, preoperative and postoperative aneurysm sac volumes were measured, in addition to aneurysm characteristics. RESULTS:, P = 0.005). EVAR patients had greater number of lumbar arteries (7.26 ± 1.68 vs. 5.31 ± 1.93, P < 0.000001). On postoperative follow-up, FEVAR cases had greater sac regression compared to standard EVAR (-22.75 ± 25.7% vs. -5.98 ± 19.66%, P = 0.00031). The percentage of sac regression was greater when measured by volume compared to maximum diameter for FEVAR (-22.75 ± 25.7% vs. -13.90 ± 15.4%, P = 0.01) but not EVAR (-5.98 ± 19.7% vs. -4.51 ± 15.2%, P = 0.246). Those in the top tertile of percent volume of thrombus (>48.5%) were more likely to experience greater than 10% sac regression by volume (55% vs. 33.3%, P = 0.015). On multivariate analysis, FEVAR was associated with sac regression greater than 10% by volume (odds ratio [OR] 4.325, 95% confidence interval [CI] 1.346-13.901, P = 0.014), while endoleak (OR 0.162, 95% CI 0.055-0.479, P < 0.001) and 2 patent hypogastric arteries (OR 0.066, 95% CI 0.005-0.904, P = 0.042) were predictive against. CONCLUSIONS:Fenestrated EVAR is associated with greater sac regression compared to EVAR on volumetric analysis. This difference may be attributable to decreased endotension within the aneurysm resulting from less aortic neck dilatation, while the greater proportion of thrombus may be a protective factor from growth. Patients being evaluated for EVAR with borderline neck anatomy should be considered for FEVAR given increased sac regression.

BACKGROUND:Dickkopf-related protein 1 (DKK1) is a Wingless-related integrate site (Wnt) signaling modulator that is upregulated in prostate cancers (PCa) with low androgen receptor expression. DKN-01, an IgG4 that neutralizes DKK1, delays PCa growth in pre-clinical DKK1-expressing models. These data provided the rationale for a clinical trial testing DKN-01 in patients with metastatic castration-resistant PCa (mCRPC). METHODS:(combination) for men with mCRPC who progressed on ≥1 AR signaling inhibitors. DKK1 status was determined by RNA in-situ expression. The primary endpoint of the phase 1 dose escalation cohorts was the determination of the recommended phase 2 dose (RP2D). The primary endpoint of the phase 2 expansion cohorts was objective response rate by iRECIST criteria in patients treated with the combination. RESULTS:18 pts were enrolled into the study-10 patients in the monotherapy cohorts and 8 patients in the combination cohorts. No DLTs were observed and DKN-01 600 mg was determined as the RP2D. A best overall response of stable disease occurred in two out of seven (29%) evaluable patients in the monotherapy cohort. In the combination cohort, five out of seven (71%) evaluable patients had a partial response (PR). A median rPFS of 5.7 months was observed in the combination cohort. In the combination cohort, the median tumoral DKK1 expression H-score was 0.75 and the rPFS observed was similar between patients with DKK1 H-score ≥1 versus H-score = 0. CONCLUSION/CONCLUSIONS:DKN-01 600 mg was well tolerated. DKK1 blockade has modest anti-tumor activity as a monotherapy for mCRPC. Anti-tumor activity was observed in the combination cohorts, but the response duration was limited. DKK1 expression in the majority of mCRPC is low and did not clearly correlate with anti-tumor activity of DKN-01 plus docetaxel.

BACKGROUND:Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy associated with a high risk of ventricular arrhythmia (VA). Several animal models have been used to postulate a therapeutic role of the inhibition of the ryanodine 2 receptor via the use of flecainide for this disease. Clinical data describing its use are scarce, however, especially in patients without implantable cardioverter-defibrillators or with left ventricular (LV) involvement. OBJECTIVES/OBJECTIVE:This study sought to report safety and effectiveness long-term, multicenter data on the impact of flecainide therapy on arrhythmic outcomes in patients with a definite diagnosis of ARVC. METHODS:Patients with definite ARVC receiving flecainide at 12 academic institutions were enrolled in the study. Baseline was defined as the time of flecainide initiation. Premature ventricular complex burdens, nonsustained ventricular tachycardia (NSVT) rates, and sustained VA yearly/rates were collected and compared while on and off flecainide. Side effects and flecainide discontinuation were tracked. Analyses were performed in the overall cohort as well as stratifying for genotype (gene positive vs negative; plakohpillin-2 [PKP-2] vs non PKP-2) and for LV involvement. RESULTS:; LV ejection fraction 55.9 ± 7.3%; right ventricular ejection fraction 44.5 ± 10.5% at baseline) were enrolled, with 66 patients (34.6%) showing LV involvement. The median dose of flecainide was 200 mg/d [150-200 mg/d], with 166 patients (86.9%) also taking a beta-blocker. The median follow-up time on flecainide was 4.2 years [1.9-6.3 years]. Flecainide was well tolerated, with a low (7.9%) discontinuation rate. After flecainide initiation, a significant reduction in the 24-hour premature ventricular complex burden and in the rate of nonsustained ventricular tachycardia was observed (2,190 vs 418; P < 0.001; 35.1% vs 21.5%; P = 0.003). For patients with prior VA events, a significant reduction in the amount of VA episodes/y (1.1 [0.4-1.6] episodes/y vs 0 [0-0.3] episodes/y; P < 0.001) was observed. These safety and effectiveness findings were consistent across genotype subgroups, as well as in patients with and without LV involvement. CONCLUSIONS:Flecainide use had a favorable safety profile and was associated with an observed to a significant reduction in arrhythmic burden in patients with ARVC, irrespective of the underlying genotype or LV involvement.

Epilepsy is a chronic condition characterized by unpredictable and recurrent spontaneous seizures. In a previous study, we reported that pharmacological inhibition of calpain prevented epileptogenesis in the rat pilocarpine model. In this study, we demonstrate that transgenic overexpression of calpastatin, the endogenous inhibitor of calpain, reduces calpain activation and lessens seizure burden in the mouse intrahippocampal kainate model. Blockade of calpain activation was evidenced by a reduction in the generation of spectrin breakdown products, a hallmark of calpain activation. CAST overexpression was associated with a significant reduction in seizure burden, further supporting the idea that blocking calpain overactivation prevents epilepsy. Moreover, a reduction in seizure burden was accompanied by a decrease in inflammatory markers but not cell death. Together, these observations corroborate the role of calpain overactivation in epileptogenesis and provide further support for the use of calpain inhibitors as a viable strategy to prevent epilepsy. PLAIN LANGUAGE SUMMARY: The mechanisms by which brain alterations lead to spontaneous seizures are not well understood. Acquired epilepsy often follows brain trauma. After a brain injury, the activation of the protease calpain has been associated with the development of spontaneous seizures. Our observations indicate that transgenic overexpression of calpastatin, an endogenous inhibitor of calpain, impacts epileptogenesis and reduces seizure burden. This suggests that inhibiting calpain could be a viable strategy to prevent epilepsy.

Uncontrolled activation of the rat sarcoma (RAS)-extracellular signal-regulated kinase (ERK) pathway drives tumor growth, often because of oncogenic BRAF mutations. BRAF regulation, involving monomeric autoinhibition and activation by dimerization, has been intensely scrutinized, but mechanisms enabling oncogenic mutants to evade regulation remain unclear. By using cryo-electron microscopy, we solved the three-dimensional structures of the three oncogenic BRAF mutant classes, including the common V600E variant. These mutations disrupted wild-type BRAF's autoinhibited state, mediated by interactions between the cysteine-rich domain and kinase domain, thereby shifting the kinase domain into a preactivated conformation. This structural change likely results from helix αC displacement. PLX8394, a BRAF inhibitor that stabilizes helix αC in an inactive conformation, restored the autoinhibited conformation of oncogenic BRAF, explaining the properties of this class of compounds.

Heart failure (HF) often coexists with cancer. Beyond the known cardiotoxicity of some cancer treatments, HF itself has been associated with increased cancer incidence. The 2 conditions share common risk factors, mechanisms, and interactions that can worsen patient outcomes. The bidirectional relationship between HF and cancer presents a complex interplay of factors that are not fully understood. Recent preclinical evidence suggests that HF may promote tumor growth via the release of protumorigenic factors from the injured heart, revealing HF as a potentially protumorigenic condition. Our review discusses the biological crosstalk between HF and cancer, emphasizing the impact of HF on tumor growth, with inflammation, and modulating the immune system as central mechanisms. We further explore the clinical implications of this connection and propose future research directions. Understanding the mechanistic overlap and interactions between HF and cancer could lead to new biomarkers and therapies, addressing the growing prevalence of both conditions and enhancing approaches to diagnosis, prevention, and treatment.

Angiopoietin-like 3 (ANGPTL3) inhibits lipases that hydrolyze triglycerides (TGs) in TG-rich lipoproteins (TRLs). We evaluated TRL-TGs, TRL particle (apolipoprotein B), palmitate, and glucose kinetics during a mixed-meal test that included intravenous and oral tracer administrations in people with extremely rare compound heterozygous ANGTPL3 loss-of-function mutations (ANGPTL3^-/- group, n = 3) and matched control participants (n = 7). Multi-organ (liver, muscle, and adipose tissue) insulin sensitivity was evaluated with a two-step hyperinsulinemic-euglycemic clamp procedure and glucose and palmitate tracer infusions. We find that plasma TG and TRL particle concentrations are more than 10-fold lower in the ANGPTL3^-/- than in the control group due to both markedly reduced liver-derived TRL particle and TG secretion rates combined with increased plasma clearance of both liver- and gut-derived TRLs. Palmitate and glucose kinetics during the meal test are not different between the groups. We conclude that the biological function of ANGPTL3 reaches beyond inhibiting intravascular lipase activity.

Huntington's disease (HD) is caused by the expansion of the polyglutamine stretch in huntingtin protein (HTT) resulting in hallmark aggresomes/inclusion bodies (IBs) composed of mutant huntingtin protein (mHTT) and its fragments. Stimulating autophagy to enhance mHTT clearance is considered a potential therapeutic strategy for HD. Our recent evaluation of the autophagic-lysosomal pathway (ALP) in human HD brain reveals upregulated lysosomal biogenesis and relatively normal autophagy flux in early Vonsattel grade brains, but impaired autolysosome clearance in late grade brains, suggesting that autophagy stimulation could have therapeutic benefits as an early clinical intervention. Here, we tested this hypothesis by crossing the Q175 HD knock-in model with our autophagy reporter mouse TRGL (Thy-1-RFP-GFP-LC3) to investigate in vivo neuronal ALP dynamics. In the Q175 and/or TRGL/Q175 mice, mHTT was detected in autophagic vacuoles and also exhibited a high level of colocalization with autophagy receptors p62/SQSTM1 and ubiquitin in the IBs. Compared to the robust lysosomal pathology in late-stage human HD striatum, ALP alterations in Q175 models are also late-onset but milder, that included a lowered phospho-p70S6K level, lysosome depletion, and autolysosome elevation including more poorly acidified autolysosomes and larger-sized lipofuscin granules, reflecting impaired autophagic flux. Administration of a mTOR inhibitor to 6-mo-old TRGL/Q175 normalized lysosome number, ameliorated aggresome pathology while reducing mHTT-, p62-, and ubiquitin-immunoreactivities, suggesting the beneficial potential of autophagy modulation at early stages of disease progression.

Cardiolipin (CL), the signature phospholipid of mitochondria, carries four fatty acids that are remodeled after de novo synthesis. In yeast, remodeling is accomplished by the joint action of Cld1, a lipase that removes a fatty acid from CL, and Taz1, a transacylase that transfers a fatty acid from another phospholipid to monolyso-CL. While taz1 homologues have been identified in all eukaryotes, cld1 homologues have remained obscure. Here we demonstrate that ABHD18, a highly conserved protein of plants, animals, and humans, is functionally homologous to Cld1. Knockdown of Abhd18 decreased the concentration of monolyso-CL in murine, Taz-knockout myoblasts. Inactivation of Abhd18 in Drosophila substantially increased the abundance of CL. Abhd18 inactivation also reversed the increase in the rate of CL degradation, as measured with ¹³C isotopes, and the accumulation of deacylated CLs, such as monolyso-CL and dilyso-CL, in TAZ-deficient flies. CL species with more than 5 double bonds were resistant to ABHD18. Our data demonstrate that ABHD18 is the elusive lipase that hydrolyzes CL in mice and flies and presumably in other organisms. Rather than removing just one fatty acid, we show that ABHD18 deacylates CL further. Thus, ABHD18 catalyzes the breakdown of CL whereas TAZ protects CL from degradation.