Oesophageal cell collection device and biomarker testing to identify high-risk Barrett's patients requiring endoscopic investigation.

BACKGROUND: Barrett's oesophagus surveillance places significant burden on endoscopy services yet is vital to detect early cancerous change. Oesophageal cell collection device (OCCD) testing was introduced across Scotland for Barrett's surveillance in response to the COVID-19 pandemic. This national pragmatic retrospective study presents the CytoSCOT programme results and evaluates whether OCCD testing is successfully identifying high-risk Barrett's patients requiring urgent endoscopy. METHODS: All patients undergoing OCCD testing for Barrett's surveillance across 11 Scottish health boards over a 32-month period were identified. Patients who underwent endoscopy within 12 months of OCCD test were included. Individual patient records were interrogated to record clinical information and OCCD test result to categorize patients into risk groups. Endoscopic histopathology results were analysed according to risk group and segment length. Patients were deemed high risk if the OCCD test demonstrated atypia and/or p53 positivity. RESULTS: 4204 OCCD tests were performed in 3745 patients: 608 patients underwent endoscopy within 12 months and were included in this analysis. Patients with longer Barrett's segments were significantly more likely to have an abnormal OCCD test. 50/608 patients (8.2%) had high-grade dysplasia or cancer on endoscopic biopsies: this equates to 1.3% of the total group (50/3745). 46/50 patients (92.0%) were deemed high risk, triggering urgent endoscopy: this rose to 100% with insufficient tests removed. There were no cancers diagnosed within 12 months post-OCCD in the low-risk group. CONCLUSION: OCCD testing is an effective triage tool to identify high-risk patients with Barrett's oesophagus requiring further investigation with endoscopy within the real-world setting.

KIT ATP-Binding Pocket/Activation Loop Mutations in GI Stromal Tumor: Emerging Mechanisms of Kinase Inhibitor Escape.

PURPOSE: Imatinib resistance in GI stromal tumors (GISTs) is primarily caused by secondary KIT mutations, and clonal heterogeneity of these secondary mutations represents a major treatment obstacle. KIT inhibitors used after imatinib have clinical activity, albeit with limited benefit. Ripretinib is a potent inhibitor of secondary KIT mutations in the activation loop (AL). However, clinical benefit in fourth line remains limited and the molecular mechanisms of ripretinib resistance are largely unknown. PATIENTS AND METHODS: Progressing lesions of 25 patients with GISTs refractory to ripretinib were sequenced for KIT resistance mutations. Resistant genotypes were validated and characterized using novel cell line models and in silico modeling. RESULTS: GISTs progressing on ripretinib were enriched for secondary mutations in the ATP-binding pocket (AP), which frequently occur in cis with preexisting AL mutations, resulting in highly resistant AP/AL genotypes. AP/AL mutations were rarely observed in a cohort of progressing GIST samples from the preripretinib era but represented 50% of secondary KIT mutations in patients with tumors resistant to ripretinib. In GIST cell lines harboring secondary KIT AL mutations, the sole genomic escape mechanisms during ripretinib drug selection were AP/AL mutations. Ripretinib and sunitinib synergize against mixed clones with secondary AP or AL mutants but do not suppress clones with AP/AL genotypes. CONCLUSION: Our findings underscore that KIT remains the central oncogenic driver even in late lines of GIST therapy. KIT-inhibitor combinations may suppress resistance because of secondary KIT mutations. However, the emergence of KIT AP/AL mutations after ripretinib treatment calls for new strategies in the development of next-generation KIT inhibitors.

National adoption of an esophageal cell collection device for Barrett's esophagus surveillance: impact on delay to investigation and pathological findings.

High quality Barrett's esophagus surveillance is crucial to detect early neoplastic changes. An esophageal cell collection device (OCCD) was introduced as a triage tool for Barrett's surveillance. This study aims to evaluate whether the Scottish OCCD program (CytoSCOT) has reduced delays to Barrett's surveillance, and whether delayed surveillance negatively impacts endoscopic pathology. All patients undergoing OCCD testing for Barrett's surveillance across 11 Scottish health boards between 14/9/2020 and 13/9/2022 were identified. Patients were dichotomised into two groups (Year 1 vs. Year 2), with individual records interrogated to record demographics, recommended surveillance interval, time from last endoscopy to OCCD test, and OCCD result. Patients were deemed high-risk if the OCCD demonstrated atypia and/or p53 positivity. Further analysis was performed on patients who underwent endoscopy within 12 months of OCCD testing. A total of 3223 OCCD tests were included in the analysis (1478 in Year 1; 1745 in Year 2). In Year 1 versus Year 2, there was a longer median delay to surveillance (9 vs. 5 months; P < 0.001), increased proportion of patients with delayed surveillance (72.6% vs. 57.0%; P < 0.001), and more high-risk patients (12.0% vs. 5.3%; P < 0.001). 425/3223 patients (13.2%) were further investigated with upper gastrointestinal endoscopy, 57.9% of which were high-risk. As surveillance delay increased beyond 24 months, high-risk patients were significantly more likely to develop dysplasia or malignancy (P = 0.004). Delayed Barrett's esophagus surveillance beyond 24 months is associated with increased risk of pre-cancerous pathology. The CytoSCOT program has reduced delays in surveillance, promoting earlier detection of dysplasia and reducing burden on endoscopy services.