Abstract 4018: Long-term response to Trastuzumab in patients with advanced gastric or gastroesophageal adenocarcinoma - A retrospective study

Since 2010, Trastuzumab combined with chemotherapy is the standard treatment for patients with HER2 (ERBB2) positive advanced or metastatic gastric and gastroesophageal junction cancer (GGEJ). While few patients show long-term response to the treatment, most suffer from rapid disease progression. Several studies revealed that genomic alterations, gene expression changes and altered HER2 signaling activity contribute to impaired therapy response. However, the underlying mechanism remains unclear. The aim of this research project is to analyze differences between patients with long and short progression-free survival by utilizing combined genetic, histologic, clinical and gene expression data. We collected a retrospective German patient cohort (n=20) including patients with HER2 positive advanced GGEJ who received Trastuzumab combined with chemotherapy. Using archival samples that were obtained prior to Trastuzumab treatment, we created a dataset including clinical information, histologic assessment, immunostaining, target amplicon sequencing (TAS; 409 gene panel) and human transcriptome data using the Affymetrix platform. To analyze the TAS sequencing data, we generated an automated analysis pipeline, which detects single nucleotide variants (SNV) and copy number alterations (CNA). Information about genomic alteration will be correlated with pathway and gene set enrichment analysis (GSEA) from the Affymetrix data. Furthermore, the data will be supported by investigating the functional status of HER2 in patient samples via electron microscopy. The results of this study could give insights on how genetic and transcriptomic alterations are connected to long-term Trastuzumab therapy response in HER2 positive GGEJ patients. This could potentially support therapy decision in personalized medicine.

Citation Format: Isabel Porth, Philip Weidner, Sylvie Lorenzen, Wilko Weichert, Thorsten Oliver Götze, Sven Perner, Kim Luley, Daniela Hirsch, Ralf-Dieter Hofheinz, Diana B. Peckys, Zahra Mostajeran, Niels de Jonge, Timo Gaiser. Long-term response to Trastuzumab in patients with advanced gastric or gastroesophageal adenocarcinoma - A retrospective study [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 4018.

Correlative Fluorescence- and Electron Microscopy of Whole Breast Cancer Cells Reveals Different Distribution of ErbB2 Dependent on Underlying Actin

Epidermal growth factor receptor 2 (ErbB2) is found overexpressed in several cancers, such as gastric, and breast cancer, and is, therefore, an important therapeutic target. ErbB2 plays a central role in cancer cell invasiveness, and is associated with cytoskeletal reorganization. In order to study the spatial correlation of single ErbB2 proteins and actin filaments, we applied correlative fluorescence microscopy (FM), and scanning transmission electron microscopy (STEM) to image specifically labeled SKBR3 breast cancer cells. The breast cancer cells were grown on microchips, transformed to express an actin-green fluorescent protein (GFP) fusion protein, and labeled with quantum dot (QD) nanoparticles attached to specific anti-ErbB2 Affibodies. FM was performed to identify cellular regions with spatially correlated actin and ErbB2 expression. For STEM of the intact plasma membrane of whole cells, the cells were fixed and covered with graphene. Spatial distribution patterns of ErbB2 in the actin rich ruffled membrane regions were examined, and compared to adjacent actin-low regions of the same cell, revealing an association of putative signaling active ErbB2 homodimers with actin-rich regions. ErbB2 homodimers were found absent from actin-low membrane regions, as well as after treatment of cells with Cytochalasin D, which breaks up larger actin filaments. In both latter data sets, a significant inter-label distance of 36 nm was identified, possibly indicating an indirect attachment to helical actin filaments via the formation of heterodimers of ErbB2 with epidermal growth factor receptor (EGFR). The possible attachment to actin filaments was further explored by identifying linear QD-chains in actin-rich regions, which also showed an inter-label distance of 36 nm.

Effect of Implants on Maximum Bite Force in Edentulous Patients

One of the main goals of prosthetic dentistry is to reconstruct the masticatory system. Replacing missing teeth by complete or partial denture is associated with decreased bite force and patient satisfaction. The aim of the present study was to measure the maximum bite force (MBF) and to evaluate patients' satisfaction from their conventional complete dentures and their mandibular implant-supported overdentures opposed by complete denture. In this cross sectional analytical descriptive study, seventy-five 45- to 65-year-old patients were divided into 3 groups wearing: (1) conventional complete dentures for up to 6 months; (2) conventional complete dentures for 10 years or more; and (3) complete maxillary dentures opposing mandibular implant-supported overdentures. Bite force was measured by means of electronic bite force measuring device with strain gauges. Three measurements were made on each side on the first molar region and the mean values were recorded. Patient satisfaction was also recorded using questionnaires. Results were analyzed by analysis of variance (ANOVA), t test, chi-square, and Pearson correlation test. The mean MBF for the first, the second, and the third group was, respectively, 5.65 ± 1.46 kgf, 7.01 ± 2.1 kgf, and 12.22 ± 27 kgf. The difference between MBF in patients with overdentures and in patients with conventional complete dentures was statistically significant (P  =  .001). Patient satisfaction with mandibular implant-supported overdentures was recorded as “great.” Results indicated MBF in the patients with mandibular implant-supported overdentures was significantly higher than that of patients with conventional complete dentures. This difference may indicate the important role of dental implants in the improvement of bite force and chewing efficiency and therefore patients' satisfaction.