Replicative stress in gastroesophageal cancer is associated with chromosomal instability and sensitivity to DNA damage response inhibitors

Gastroesophageal adenocarcinoma (GEA) is an aggressive malignancy with chromosomal instability (CIN). To understand adaptive responses enabling DNA damage response (DDR) and CIN, we analyzed matched normal, premalignant, and malignant gastric lesions from human specimens and a carcinogen-induced mouse model, observing activation of replication stress, DDR, and p21 in neoplastic progression. In GEA cell lines, expression of DDR markers correlated with ploidy abnormalities, such as number of high-level focal amplifications and whole-genome duplication (WGD). Integrating TP53 status, ploidy abnormalities, and DDR markers into a compositive score helped predict GEA cell lines with enhanced sensitivity to Chk1/2 and Wee1 inhibition, either alone or combined with irinotecan (SN38). We demonstrate that Chk1/2 or Wee1 inhibition combined with SN38/irinotecan shows greater anti-tumor activity in human gastric cancer organoids and an in vivo xenograft mouse model. These findings indicate that specific DDR biomarkers and ploidy abnormalities may predict premalignant progression and response to DDR pathway inhibitors.

Replicative stress in gastroesophageal adenocarcinoma is associated with chromosomal instability and sensitivity to DNA damage response inhibitors

Gastroesophageal adenocarcinoma (GEA) is an aggressive, often lethal, malignancy that displays marked chromosomal instability (CIN). To understand adaptive responses that enable CIN, we analyzed paired normal, premalignant, and malignant gastric lesions from human specimens and a carcinogen-induced mouse model, observing activation of replication stress, DNA damage response (DDR), and cell cycle regulator p21 in neoplastic progression. In GEA cell lines, expression of DDR markers correlated with ploidy abnormalities, including high-level focal amplifications and whole-genome duplication (WGD). Moreover, high expression of DNA damage marker H2AX correlated with CIN, WGD, and inferior patient survival. By developing and implementing a composite diagnostic score that incorporates TP53 mutation status, ploidy abnormalities, and H2AX expression, among other genomic information, we can identify GEA cell lines with enhanced sensitivity to DDR pathway inhibitors targeting Chk1/2 and Wee1. Anti-tumor properties were further augmented in combination with irinotecan (SN38) but not gemcitabine chemotherapy. These results implicate specific DDR biomarkers and ploidy abnormalities as diagnostic proxy that may predict premalignant progression and response to DDR pathway inhibitors.

Circulating tumor DNA as a marker of recurrence risk in locoregional esophagogastric cancers with pathologic complete response

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Background: Following neoadjuvant therapy and definitive surgery, up to one-third of patients (pts) with esophageal (E), gastroesophageal junction (GEJ), and gastric (G) adenocarcinoma with a pathologic complete response (pCR) (tumor regression grade 0 [TRG0]) will experience disease recurrence, while up to one-half of pts with a near-pCR (TRG1) experience disease recurrence. Our study aims to provide real-world evidence that postoperative circulating tumor DNA (ctDNA) is prognostic of recurrence in pts with pCR or near-pCR after curative-intent neoadjuvant treatment and surgery. Methods: We identified pts from 11 institutions with stages I-III esophagogastric cancers who completed neoadjuvant therapy and had TRG0 or TRG1 scores at the time of curative-intent surgery. Postoperative plasma samples were collected for ctDNA analysis within a 16-week molecular residual disease (MRD) window after definitive surgery and serially during routine clinical follow-up from 9/19/19 to 2/21/22. MRD by ctDNA was assessed using a personalized, tumor-informed ctDNA assay (bespoke Signatera mPCR-NGS assay). The primary outcome was recurrence-free survival (RFS), measured from the date of surgery to the first documented sign of radiographic recurrence. Survival analysis was performed using the maximum likelihood bias reduction method for Cox regression in R (version 4.1) package survival. Results: We obtained 250 blood samples from 42 pts with E (n=18), GEJ (n=16), and G (n=8) adenocarcinomas who received either neoadjuvant chemoradiation or chemotherapy. 11 pts had a pCR (TRG0), and 31 pts had a near-pCR (TRG1). For pts analyzed in the post-operative, 16-week MRD window (n=21), the presence of ctDNA correlated with a higher recurrence rate (66.7%; 2/3) compared to the absence of ctDNA (11.1%; 2/18). Detectable ctDNA was associated with a significantly shorter RFS (HR 23.0, 95% CI 2.0 – 268.1; p = 0.012). 38 pts had ctDNA analyzed at any post-MRD time point (>16 weeks after surgery) over a median follow-up of 22.3 months. With additional routine ctDNA testing at any post-MRD time point, the recurrence rate was 90.0% (9/10) in ctDNA-positive pts compared to 10.7% (3/28) in ctDNA-negative pts, exhibiting a further reduction in RFS (HR 44.4; 95% CI 5.4-366.3; p<0.001). The sensitivity and specificity of the ctDNA assay at any post-operative time point was 87.5% and 96.2%, respectively. Out of 10 ctDNA-positive pts, two (20%) converted from ctDNA-positive to ctDNA-negative with subsequent treatment. Conclusions: Within the subgroup of pts with favorable pathologic responses after neoadjuvant therapy (TRG 0-1), the presence of post-operative ctDNA identified pts with elevated recurrence risk. If validated in larger cohorts this approach may be used to select pts at risk for recurrence following neoadjuvant therapy, with potential implications for direction of adjuvant therapy.

Circulating tumor DNA (ctDNA) informs clinical practice in patients with recurrent/metastatic gastroesophageal cancers

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Background: Gastric and esophageal cancers (GECs) together account for a significant global burden in terms of new diagnoses and deaths. Over the last several years, the utility of ctDNA has ranged from estimating tumor burden and characterizing the genomic landscape of tumor biology and response to therapy in the metastatic setting to detection of minimal residual disease (MRD) and cancer surveillance in the locally advanced setting. We have previously studied the role of a commercial ctDNA assay for MRD detection and surveillance in locally advanced GECs. Herein, we present our experience with the same ctDNA assay in advanced stage settings for GECs. Methods: In this retrospective analysis of real-world data obtained from commercial circulating tumor DNA (ctDNA) testing, 53 patients with recurrent/ metastatic esophageal cancer were analyzed. A total of 216 plasma samples were collected between 10/29/2008 and 08/23/2022. The patients were divided into 3 cohorts: Cohort A (N=30) included patients with stage II/III disease who had confirmed clinical recurrence (R). Cohort B (N=25) included recurrent and Stage IV patients who achieved a state of no evidence of disease (NED) on imaging. Cohort C (N=5) included recurrent and Stage IV patients who transiently achieved NED on imaging. A personalized, tumor-informed multiplex PCR-based next-generation sequencing assay (Signatera) was used to quantify ctDNA either postoperatively, on adjuvant or palliative therapy, or during active surveillance. Results: Of 53 patients, 30 patients with recurrent stage II/III esophageal cancer had ctDNA status available postoperatively within 150 days of confirmed clinical recurrence. Cohort A: Among these cases, 25 patients were ctDNA-positive ahead of clinical recurrence (sensitivity 83.3%) with a median of 31 days (range: 1-147 days). Cohort B: Next, we explored the correlation between ctDNA status and imaging, wherein, 96% (24/25) of patients showed a significant correlation between ctDNA status (positive or negative) and disease status by imaging (Fisher exact test p=0.0001). Of the 23 patients, 17 patients were ctDNA-negative and showed NED on imaging (negative predictive value of 100%; 17/17). Cohort C: 100% of patients (N=6) who demonstrated recurrent disease on imaging after NED were ctDNA-positive prior to imaging (positive predictive value of 100%). Conclusions: Our data demonstrate the utility of ctDNA in accurately predicting disease progression and support the potential use of ctDNA to inform treatment decisions or prompt early radiographic imaging. ctDNA may ultimately supersede traditional radiographic surveillance with the advantage of being minimally invasive and cost-effective in monitoring patients during/post-treatment.

Opportunities for Utilization of DNA Repair Inhibitors in Homologous Recombination Repair-Deficient and Proficient Pancreatic Adenocarcinoma

Pancreatic cancer is rapidly progressive and notoriously difficult to treat with cytotoxic chemotherapy and targeted agents. Recent demonstration of the efficacy of maintenance PARP inhibition in germline BRCA mutated pancreatic cancer has raised hopes that increased understanding of the DNA damage response pathway will lead to new therapies in both homologous recombination (HR) repair-deficient and proficient pancreatic cancer. Here, we review the potential mechanisms of exploiting HR deficiency, replicative stress, and DNA damage-mediated immune activation through targeted inhibition of DNA repair regulatory proteins.

0883 Impact of Implementation of a Comprehensive Positive Airway Pressure Program

Introduction

The American Academy of Sleep Medicine (AASM) guidelines for treatment of Obstructive Sleep Apnea (OSA) with Positive Airway Pressure (PAP) state good practice standards involve adequate follow up with a clinician tele-monitoring efficacy through objective usage data to ensure acceptable treatment and compliance is met, and provide education, behavioral and/or troubleshooting interventions. In 2016, Dayton Children’s Hospital’s pap compliance was 29% due to limited staff support.

Methods

To efficiently implement the AASM guidelines, one dedicated Respiratory Therapist (RT) was assigned to help manage OSA patients at Dayton Children’s Sleep Medicine. The RT responsibilities include, PAP therapy education, arranging home PAP system, and a follow-up call within 7 days of setup. Through the tele-monitoring system, the RT assesses compliance and addresses equipment issues and mask fitting at the 4 to 6 week clinic visit. To enhance compliance, a welcome postcard and gift card were implemented. Monthly clinic visits occur until compliance is met, wearing device greater than 4 hours 60% of the time, then appointments are scheduled every 6 months to 1 year.

Results

Since 2016, compliance rate increased from 29% to 58%. There was a year over year growth of number of patients starting therapy from 2017 to 2019, 86 patients were added to the PAP program. In 2019, 60% of 6 to 12 years old met compliance and 51% of 13 to 18 years old.

Conclusion

A comprehensive PAP program resulted in improved compliance and substantial growth. Referring providers and families are more likely to accept PAP therapy when made aware of extensive education and follow up by RT staff. To further improve compliance, especially in the 13 to 18 age range, a desensitization program has recently been implemented.

Support

No support provided.

Gastrointestinal Bleeding Secondary to Iliac Artery Pseudoaneurysm in a Patient With Remote Pancreas Transplant: A Case Report

BACKGROUND

Vascular complications represent the most common cause of early graft failure after pancreatic transplantation (PT). Pseudoaneurysms are uncommon vascular complications that usually present within the first year post transplantation.

CASE REPORT

A 49-year-old man with history of type 1 diabetes mellitus presented for evaluation with a 2-day history of painless hematochezia. He had undergone PT 4 years prior to presentation, which failed due to acute cellular rejection after 1 year. Both extended upper endoscopy and colonoscopy did not identify an active bleeding source. After an episode of massive hematochezia, he became hemodynamically unstable with peritoneal signs noted on physical examination. An abdominal angiogram was unable to identify active hemorrhage, and the patient was transferred to the operating room for open laparotomy. Exploration revealed a right common iliac artery pseudoaneurysm eroding into the pancreatic-ileal anastomosis, which required initial digital compression for initial hemostasis. After combined endovascular procedure with ballooning and stenting of the right iliac artery, optimal hemostasis was achieved without further episodes of hematochezia.

DISCUSSION

Gastrointestinal bleeding (GIB) has been reported to occur in 11% of enteric-drained PT. Even though infectious causes have been reported, culprits are more commonly associated with vascular or enteric surgical anastomosis and usually occur within the early postoperative course. Here we report an uncommon cause of GIB, a late complication of PT, and review important points associated with the management of GIB, anatomy of PT, and potential etiologies for early and late GIB in the setting of PT.