Abstract 5716: Using copper chelating agents to simultaneously target epigenetic mechanisms and receptor tyrosine kinase (RTK) signaling in diffuse intrinsic pontine glioma (DIPG)

DIPG is an incurable and inoperable pediatric brain cancer in the ventral pons characterized by its complex mutational profile. Epigenetic mutations to H3K27M are seen in up to 81% of patients, resulting in the global loss of the repressive H3K27 trimethylation marker, increasing chromatin accessibility and deregulating gene expression. However, these epigenetic changes are often partnered by secondary mutations, with activating mutations and copy number gains observed in a wide variety of RTK genes and their associated signaling pathways. The combination of these two mutational paradigms results in the broad alteration of cellular and metabolic mechanisms, complicating the search for effective targeted therapeutic strategies. Copper, a metal ion essential for normal cellular function is known to be highly expressed in the pons, and influence ERK and PI3K/AKT signaling. Importantly, excess copper accumulation has been implicated in the pathogenesis of multiple neurological diseases and cancers. Copper chelation therapy is a clinically approved strategy for pediatric patients with Wilson’s Disease, known to improve their neurological symptoms, and is under investigation for use in a number of cancers. Therefore, we hypothesized copper chelation may be an effective therapeutic strategy for DIPG. Cytotoxicity assays using copper chelator tetraethylenepentamine (TEPA) demonstrated millimolar efficacy and synergized with mTOR inhibitor everolimus in a panel of DIPG cell lines, with H3-K27M mutant cell lines found to be more sensitive. Western blots were used to identify copper integrated pathways, with DIPG cell lines stimulated with sub-lethal copper concentrations demonstrating increased phosphorylated expression of ERK1/2, ERK5, AKT and p70SK61. TEPA reduced the phosphorylation of these markers compared to controls. Importantly, epigenetic mechanisms were sensitive to copper, as both copper stimulation and TEPA modulated H3K27 trimethylation, and TEPA decreased pro-expression H3K27 acetylation. In further blots examining epigenetic regulators, TEPA reduced the expression of EZH2, DNMT3B and DNMT1. RNA-sequencing analysis revealed TEPA downregulated genes involved in S-adenosylmethionine production metabolism, DNA regulation, cell cycle and mTORC signaling and specifically, EZH2, DNMT3B and DNMT1 expression. In vivo investigations demonstrated TEPA’s ability to improve survival in an orthotopic xenograft model, and via xenogen luminescence imaging complete tumor regression in 25% of treated mice. This study indicates copper directly impacts epigenetic and RTK mechanisms, and that their targeting through copper chelation agents represents a potential therapeutic strategy for DIPG, both as a single agent and in combination.

Citation Format: Filip Michniewicz, Federica Saletta, Tayla Watkinson, Daniele Mercatelli, Federico M. Giorgi, Jessica Bell, Maria Tsoli, David Ziegler, Orazio Vittorio. Using copper chelating agents to simultaneously target epigenetic mechanisms and receptor tyrosine kinase (RTK) signaling in diffuse intrinsic pontine glioma (DIPG) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5716.

DIPG-20. Copper chelation therapy targets S-adenosylmethionine (SAM) metabolism and epigenetic regulators in diffuse intrinsic pontine glioma (DIPG)

DIPG is an incurable pediatric brain cancer of the ventral pons characterized by its complex epigenetic profile. Up to 81% of patients present with mutation H3K27M, resulting in the global reduction of H3K27 trimethylation and increased H3K27 acetylation, deregulating gene expression through an aberrant pattern of epigenetic modification. These alterations affect many cellular and metabolic mechanisms, complicating the search for effective targeted therapeutic strategies. Copper is highly abundant in the pons and is essential for normal brain function and development. However, excess copper accumulation is implicated in several neurological diseases and cancers. Incidentally, recent investigations have indicated the H3-H4 dimer can interact with copper acting as a reductase enzyme. Copper chelation therapy is clinically approved for pediatric patients with Wilson’s Disease, improving their neurological symptoms, and is being trialed in several cancers. We therefore hypothesized copper chelation may represent an effective therapeutic strategy for DIPG. Copper chelator tetraethylenepentamine (TEPA) decreased cell growth and induced apoptosis in DIPG cell lines. To understand these results, unbiased RNA-seq and metabolomics analyses were performed, revealing downregulation of EZH2, DNMT1 and DNMT3B, upregulation of KDM6B and the disruption of key enzymes in the S-adenosylmethionine (SAM)-cycle. Importantly, TEPA downregulated SAM, which donates methyl groups for methylation, S-adenosylhomocysteine, its post-methylation product and α-ketoglutarate, a co-factor for KDM6B. Western blots confirmed the reduced expression of EZH2, DNMT1 and DNMT3B, with further blots examining the chromatin cell fraction revealing modulation of H3K27 trimethylation through copper or TEPA stimulation, and reduction of H3K27 acetylation by TEPA. Importantly, in vitro combinations with Panobinostat were synergistic, while in vivo investigations demonstrated TEPA improved survival in an orthotopic patient derived xenograft (PDX) model, showing complete tumor regression in 25% of treated mice. This study indicates a novel use for copper chelators as epigenetic drugs, and their potential as therapeutics for DIPG.

1466 Closed Incision Negative Pressure Wound Therapy reduces Surgical Site Infection following Emergency Laparotomy: A Propensity Matched NELA Registry Study

Background

Surgical site infection (SSI) contributes to a significant proportion of post-operative morbidity in people undergoing emergency surgery. Prophylactic closed incision negative pressure therapy (CINPT) has been shown to reduce SSI rates in patients undergoing elective laparotomy however there is limited evidence for their use in the emergency setting. This study aimed to determine whether prophylactic CINPT provides comparable SSI rate to SSD for midline incision following emergency laparotomy.

Method

A registry-based, prospective cohort study was undertaken using data from National Emergency Laparotomy Audit (NELA) database at our centre. The primary outcome measure was SSI as defined by the Centers for Disease Control (CDC) criteria. Secondary outcomes included 30-day post-operative morbidity and grade using Clavien-Dindo (CD) classification and the Comprehensive Complication Index, length of stay, 30-day mortality and readmission rates. CINPT and standard surgical dressing group were compared with respect to peri-operative characteristics and post-operative outcomes. A propensity- score matching (PSM) was performed to mitigate for selection bias.

Results

A total of 1484 patients were identified. Following PSM, a matched cohort of 474 patients were identified with 237 patients in each arm. SSI rate in CINPT cohort was found to be significantly lower compared to the SSD cohort (16.9% vs. 33.8%, p < 0.001). The rate of superficial and deep infections was higher in the standard dressing arm compared to the CINPWT, p < 0.001. There were no overall differences in 30-day morbidity and grade of post-operative complications.

Conclusions

Prophylactic CINPT in the emergency laparotomy is associated with reduced SSI rates.

A description of normal relaxed standing postures

A technique for the measurement of relaxed standing postures, called the Posturegram, is described. The method is inexpensive, non-invasive and is suited for clinical use. Recording is done by photography. The present study examines features of standing that were exhibited by 42 normal subjects, based upon the disposition of landmarks in the coronal and sagittal planes. Degrees of assymetry that would merit clinical attention were tentatively identified. Repeat observations, 1 week apart, of the disposition of landmarks were strongly correlated, although the lowest correlations applied to the region of the pelvis and lower trunk. Many highly significant correlations were found between the various tilts and deviations, suggesting that the analysis of postures will finally depend upon considering variables in groups rather than singly.