Graham, Rondell P.

AimsAdenomatoid tumours are mesothelial‐derived benign neoplasms with a predilection for the genital tract. Extragenital sites are rare and can cause significant diagnostic challenges. Herein, we describe the clinicopathological features of a cohort of adenomatoid tumours involving the gastrointestinal tract and liver in order to more clearly characterise their histological findings and aid in diagnosis.Methods and resultsThe pathology databases at four institutions were searched for adenomatoid tumours involving the gastrointestinal tract or liver, yielding eight cases. Available clinicoradiological and follow‐up data were collected from the medical records. Six tumours were incidentally discovered during imaging studies or at the time of surgical exploration for unrelated conditions; presenting symptoms were unknown in two patients. Histologically, the tumours were well‐circumscribed, although focal ill‐defined borders were present in four cases. No infiltration of adjacent structures was identified. Architectural heterogeneity was noted in five (63%) tumours; an adenoid pattern often predominated. The neoplastic cells were flattened to cuboidal with eosinophilic cytoplasm. Cytoplasmic vacuoles mimicking signet ring‐like cells were present in five (63%) cases. Three (38%) cases showed involvement of the mesothelium with reactive mesothelial hyperplasia. Cytological atypia or increased mitotic activity was not identified. The surrounding stroma ranged from oedematous/myxoid to densely hyalinised. Immunohistochemistry confirmed mesothelial origin in all cases evaluated. No patients developed recurrence of disease.ConclusionsThe current study evaluates the clinicopathological findings in a collective series of gastrointestinal and hepatic adenomatoid tumours, correlating with those described in individually reported cases. We highlight common histological features and emphasise variable findings that could mimic a malignant neoplasm.

Objectives This study sought to better characterize patient characteristics, treatment options, and outcomes for osteoclast-like giant cell carcinoma of the pancreas, a rare subtype of pancreatic adenocarcinoma. Methods This is a retrospective study of all patients with osteoclast-like giant cell carcinoma of pancreatic origin treated at Mayo Clinic from 2000 to present. Baseline patient characteristics, treatment modalities utilized, and outcomes were compiled. Overall survival (OS) and progression-free survival were assessed using Kaplan-Meier analysis with a significance level of P ≤ 0.05. Results Fifteen patients met criteria for inclusion. Four patients had distant metastases at diagnosis, the remaining 11 with locoregional disease. Median OS for the entire cohort was 11 months. Metastatic disease was associated with significantly shorter OS (3.5 vs 14.1 months; P = 0.005). Three patients had no evidence of disease at time of analysis; all 3 were treated with complete resection followed by adjuvant chemotherapy. Conclusions Osteoclast-like giant cell carcinoma of the pancreas is an aggressive malignancy with poor prognosis. For patients with locoregional disease, surgical resection followed by adjuvant chemoradiation may play a role in extended disease-free survival. Metastatic disease presents a challenging entity to treat with little data to support any effective chemotherapy regimens.

Abstract Background and Objectives Pancreatic neuroendocrine tumors (pNETs) in patients with hereditary cancer syndromes are typically multifocal. In contrast, sporadic pNETs are usually unifocal and the incidence of multifocal sporadic pNETs is unknown. The primary aim of this study was to investigate the incidence of multifocality in sporadic pNETs and any associated effect on recurrence risk and survival. Methods Patients who underwent resection of pNETs at Mayo Clinic from 2000 to 2019 were identified and clinical data were obtained from medical records. Syndromic disease was defined as pNETs arising in the setting of a hereditary cancer syndrome. Statistical comparisons were made using χ 2 , Fisher's exact, and Kruskal–Wallis tests and survival was assessed using the Kaplan–Meier method. Results Six hundred and sixty‐one patients with sporadic pNETs and fifty‐nine with syndromic pNETs were identified. Multifocal disease was present in 4.8% of sporadic patients and 84.7% of syndromic patients ( p < .001). Within patients with sporadic pNETs, clinicopathologic features and recurrence‐free and overall survival were similar between patients with unifocal and multifocal disease. Conclusions Multifocal sporadic pNETs are rare and multifocality is not associated with worse survival or increased recurrence risk. Patients with multifocal sporadic pNETs can likely be safely managed with a combination of resection and observation as indicated for each tumor.

Pancreatic ductal adenocarcinoma is a recalcitrant tumor with minimal response to conventional chemotherapeutic approaches. Oncogenic signaling by activated tyrosine kinases has been implicated in cancers resulting in activation of diverse effector signaling pathways. Thus, the discovery of aberrantly activated tyrosine kinases is of great interest in developing novel therapeutic strategies in the treatment and management of pancreatic cancer. Patient-derived tumor xenografts (PDXs) in mice serve as potentially valuable preclinical models as they maintain the histological and molecular heterogeneity of the original human tumor. Here, we employed high-resolution mass spectrometry combined with immunoaffinity purification using anti-phosphotyrosine antibodies to profile tyrosine phosphoproteome across 13 pancreatic ductal adenocarcinoma PDX models. This analysis resulted in the identification of 1199 tyrosine-phosphorylated sites mapping to 704 proteins. The mass spectrometric analysis revealed widespread and heterogeneous activation of both receptor and non-receptor tyrosine kinases. Preclinical studies confirmed ephrin type-B receptor 4 (EphB4) as a potential therapeutic target based on the efficacy of human serum albumin-conjugated soluble EphB4 in mice bearing orthotopic xenografts. Immunohistochemistry-based validation using tissue microarrays from 346 patients with PDAC showed significant expression of EphB4 in >70% of patients. In summary, we present a comprehensive landscape of tyrosine phosphoproteome with EphB4 as a promising therapeutic target in pancreatic ductal adenocarcinoma.

Abstract Background: Mixed acinar neuroendocrine carcinoma (MANEC) of the pancreas is an extremely rare histopathologic subtype. MANEC is an amphicrine malignancy composed of at least 25% of acinar cell carcinoma (PACC) and neuroendocrine carcinoma (pNET). No standard systemic treatment is available for MANEC and current recommendations are derived from standard of care for PACC or pNET. Platinum based regimens have been approved for PACC while targeted agents (sunitinib and everolimus) are approved for pNET. This study aimed to investigate the antitumor effect and toxicities of both platinum based and targeted agents on a successfully first described patient derived xenograft (PDX) of metastatic MANEC of the pancreas. Methods: Several generations of PDX from a surgically resected metastatic MANEC of the pancreas was histologically validated. PDX-MANEC tumors were heterotopically implanted into NOD/SCID mice and randomized into 6 groups (4 mice each) as in table 1. The study continued for 3 weeks. Antitumor efficacy was determined based on change in the tumor volume. Toxicity was assessed change in mice weights. Results: Table 1 shows the changes in tumor volume and mouse weight in all study arms compared to controls end point. Only FOLFIRINOX and gemcitabine/cisplatin arms revealed overall decrease in tumor volume lower than starting volume in controls. All arms other than sunitinib, led to decrease in overall tumor volume compared to control tumor volumes over time. All treatment arms led to lower trending mouse weights (toxicities) except sunitinib, however only the everolimus arm had statistical significance. Conclusion: Both platinum-based regimens and everolimus revealed significant tumor control. No synergistic effect observed in sunitinib/everolimus. Preclinical studies are undergoing to investigate other effective and less toxic therapeutics for MANEC. Table 1.Delta in tumor volumes of PDX-MANEC-P after multiple platinum-based chemotherapy regimens and targeted therapeutics from the standard of care for other pancreatic cancer subtypes including PACC and pNET.ControlFOLFIRINOXGemcitabine and CisplatinSunitinibEverolimusSunitinib and EverolimusDelta in tumor volume in mm3 at the study end (mean ± standard deviation)3225 ± 2054-609.3 ± 351.8-654.7 ± 92.561583 ± 950.3-178.1 ± 61.58-160.8 ± 86.55P value (column group vs. control)&lt;0.0010.0030.0950.0010.001Delta in mice weight in grams at the study end (mean ± standard deviation)0.84 ± 1.68-1.26 ± 0.84-8.5 ± 1.630.86 ± 1.22-2.2 ± 1.61-1.42 ± 1.27P value (column group vs. control)0.058&lt;0.0010.9810.0070.050 Citation Format: Amro M. Abdelrahman, Jennifer A. Yonkus, Roberto Alva-Ruiz, Jennifer L. Leiting, Nellie A. Campbell, Lewis R. Roberts, Michael L. Kendrick, David M. Nagorney, Sean P. Cleary, Travis E. Grotz, Gregory J. Gores, Jun Yin, Rondell P. Graham, Thorvardur R. Halfdanarson, Rory L. Smoot, Mark J. Truty. Preclinical efficacy of platinum based chemotherapy regimens and targeted therapeutics in the first successful described patient derived xenograft model of mixed acinar neuroendocrine carcinoma of the pancreas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 413.

AimsThe diagnosis of focal nodular hyperplasia (FNH) and the interpretation of glutamine synthetase (GS) staining can be challenging on biopsies. We aimed to evaluate the reproducibility of needle biopsy diagnosis of FNH, the effect of GS immunohistochemistry on FNH diagnosis, and which histological features are most useful for the diagnosis of FNH.Methods and resultsThe study included virtual needle biopsies generated from 75 resection specimens (30 FNHs, 15 hepatocellular adenomas, 15 hepatocellular carcinomas, and 15 non‐lesional liver specimens). Pathologists were reasonably accurate (83.1%) in the diagnosis of FNH with haematoxylin and eosin alone. Ductular reaction and nodularity had the highest sensitivity for a diagnosis of FNH (88.1% and 82.2%, respectively), whereas central scar was the most specific feature (90.6%). The presence of two or more of the classic histological features had 89.6% sensitivity and 86.2% specificity for a diagnosis of FNH. Diagnostic accuracy was significantly higher with the addition of a GS stain. A map‐like GS staining pattern was highly specific (99.3%) for FNH. However, GS staining was interpreted as non‐map‐like in 14.4% of reviews of true FNH cases, and overall interobserver agreement for interpretation of the GS staining pattern was only moderate (kappa = 0.42).ConclusionsPathologists are reasonably accurate in the diagnosis of FNH on virtual biopsies, and GS staining improves accuracy. However, a subset of FNH cases remain challenging. Steatosis and a pseudo‐map‐like GS staining pattern were associated with increased difficulty. Therefore, although a map‐like GS staining pattern is useful for confirmation of a diagnosis, the lack of a map‐like GS staining pattern on needle biopsy does not necessarily exclude a diagnosis of FNH.

5526 Background: HR-HPV DNA testing, with or without cervical cytology, provides excellent sensitivity for detection of cervical cancer (CC) and its precursors; negative test results indicate that risk of disease is extremely low and enable women to undergo reduced screening with safety. However, management of women who screen positive remains challenging as many will prove to have self-limited HR-HPV infections. DNA methylation is an early event in carcinogenesis that could enhance CC screening specificity. Methods: For discovery, DNA from 70 FFPE CC (36 squamous, 34 adenocarcinoma) tissues that were reviewed microscopically, 18 fresh frozen benign cervicovaginal (BCV) tissues collected at the time of benign hysterectomy, and 18 buffy coats from cancer-free women underwent reduced representation bisulfite sequencing (RRBS) to identify MDMs associated with CC. Candidate MDM selection was based on area under the receiver operating characteristic curve (AUC) discrimination, methylation fold change, and low background methylation among benign controls. Candidate MDMs were re-tested using methylation-specific PCR (MSP) to confirm performance. Blinded biological validation was performed using MSP on DNA extracted from independent FFPE CC (38 squamous, 43 adenocarcinoma) and BCV (40) tissues. The performance of CC MDMs was also tested in DNA extracted from cervical dysplasia (36 adenocarcinoma in situ (AIS), 32 cervical intraepithelial neoplasia (CIN) 2/3, 11 CIN 1) FFPE tissues. Results: From RRBS discovery and technical validation via MSP, 30 candidate MDMs showed marked methylation fold changes (10 to >1000) across both CC histologies compared to BCV tissue from cancer-free women. Each of the 30 MDMs highly discriminated CC from BCV tissue with 9 MDMs having an AUC >0.90 (Table). CC MDMs also highly discriminated AIS from BCV but did not perform well in CIN 2/3 and CIN 1 (Table). Conclusions: Whole methylome sequencing, stringent filtering criteria, and biological validation have yielded outstanding candidate MDMs for CC that highly discriminate CC from BCV, notably with high specificity. Performance in cervical dysplasias varied with higher positivity rates in AIS than in CIN 2/3 and CIN 1. Translation to testing these novel MDMs in lower genital tract biospecimens and the addition of HR-HPV to the CC panel are warranted.[Table: see text]

Abstract Purpose: Small-bowel adenocarcinoma (SBA) is rare, and no standard of care exists for metastatic disease beyond first-line FOLFOX/CAPOX. SBA has higher rates of microsatellite instability (MSI-H) and T-lymphocyte infiltration than other gastrointestinal cancers. We hypothesize that pembrolizumab, a PD-1 inhibitor, will induce antitumor response. Patients and Methods: Patients with previously treated advanced SBA received pembrolizumab 200 mg i.v. every 3 weeks until disease progression (PD), toxicity, or 35 doses maximum. Primary endpoint was confirmed overall response rate (ORR) with secondary progression-free survival (PFS), overall survival (OS), and toxicity assessment endpoints. Outcomes were stratified by tumor location, microsatellite stability (MSS) or instability (MSI-H), and PD-L1 level. Results: Forty patients were treated for a median duration of four cycles (range, 1–35). All patients are off study treatment due to PD (75%), death (10%), 35 cycles completed (8%), refusal (3%), and adverse effects (AEs, 5%). Three confirmed partial responses [PRs; 8%; 95% confidence interval (CI), 2–20] did not meet predefined success criteria of ORR 30%. Median OS (7.1 months; 95% CI, 5.1–17.1) and median PFS (2.8 months; 95% CI, 2.7–4.2) were similar across primary tumor sites. One confirmed PR (3%) was seen in patients with low MSS/MSI tumors and correlated with high tumor mutation burden (TMB). Fifty percent of patients with MSI-H tumors achieved PR and remain alive without progression. Twenty-five patients (63%) had grade ≥3 AEs and 11 patients (28%) had grade 4/5 AEs. Conclusions: In the largest study of SBA to date, pembrolizumab did not induce the hypothesized response rate; however, we did identify responses in key biomarker-selected cohorts.

AbstractThrough our involvement in KEYNOTE‐059, we unexpectedly observed durable responses in two patients with metastatic gastroesophageal adenocarcinoma (mGEA) who received ramucirumab (anti‐VEGFR‐2)/paclitaxel after immune checkpoint inhibition (ICI). To assess the reproducibility of this observation, we piloted an approach to administer ramucirumab/paclitaxel after ICI in more patients, and explored changes in the immune microenvironment. Nineteen consecutive patients with mGEA received ICI followed by ramucirumab/paclitaxel. Most (95%) did not respond to ICI, yet after irRECIST‐defined progression on ICI, all patients experienced tumor size reduction on ramucirumab/paclitaxel. The objective response rate (ORR) and progression‐free survival (PFS) on ramucirumab/paclitaxel after ICI were higher than on the last chemotherapy before ICI in the same group of patients (ORR, 58.8% vs 11.8%; PFS 12.2 vs 3.0 months; respectively). Paired tumor biopsies examined by imaging mass cytometry showed a median 5.5‐fold (range 4‐121) lower frequency of immunosuppressive forkhead box P3+ regulatory T cells with relatively preserved CD8+ T cells, post‐treatment versus pre‐treatment (n = 5 pairs). We then compared the outcomes of these 19 patients with a separate group who received ramucirumab/paclitaxel without preceding ICI (n = 68). Median overall survival on ramucirumab/paclitaxel was longer with (vs without) immediately preceding ICI (14.8 vs 7.4 months) including after multivariate analysis, as was PFS. In our small clinical series, outcomes appeared improved on anti‐VEGFR‐2/paclitaxel treatment when preceded by ICI, in association with alterations in the immune microenvironment. However, further investigation is needed to determine the generalizability of these data. Prospective clinical trials to evaluate sequential treatment with ICI followed by anti‐VEGF(R)/taxane are underway.