Journal of Pathology and Translational Medicine

Volume 58(3); May 2024

Review

Interpretation of PD-L1 expression in gastric cancer: summary of a consensus meeting of Korean gastrointestinal pathologists: Soomin Ahn, Yoonjin Kwak, Gui Young Kwon, Kyoung-Mee Kim, Moonsik Kim, Hyunki Kim, Young Soo Park, Hyeon Jeong Oh, Kyoungyul Lee, Sung Hak Lee, Hye Seung Lee; J Pathol Transl Med. 2024;58(3):103-116. Published online April 25, 2024; DOI: https://doi.org/10.4132/jptm.2024.03.15

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2 Crossref

Nivolumab plus chemotherapy in the first-line setting has demonstrated clinical efficacy in patients with human epidermal growth factor receptor 2–negative advanced or metastatic gastric cancer, and is currently indicated as a standard treatment. Programmed death-ligand 1 (PD-L1) expression is an important biomarker for predicting response to anti–programmed death 1/PD-L1 agents in several solid tumors, including gastric cancer. In the CheckMate-649 trial, significant clinical improvements were observed in patients with PD-L1 combined positive score (CPS) ≥ 5, determined using the 28-8 pharmDx assay. Accordingly, an accurate interpretation of PD-L1 CPS, especially at a cutoff of 5, is important. The CPS method evaluates both immune and tumor cells and provides a comprehensive assessment of PD-L1 expression in the tumor microenvironment of gastric cancer. However, CPS evaluation has several limitations, one of which is poor interobserver concordance among pathologists. Despite these limitations, clinical indications relying on PD-L1 CPS are increasing. In response, Korean gastrointestinal pathologists held a consensus meeting for the interpretation of PD-L1 CPS in gastric cancer. Eleven pathologists reviewed 20 PD-L1 slides with a CPS cutoff close to 5, stained with the 28-8 pharmDx assay, and determined the consensus scores. The issues observed in discrepant cases were discussed. In this review, we present cases of gastric cancer with consensus PD-L1 CPS. In addition, we briefly touch upon current practices and clinical issues associated with assays used for the assessment of PD-L1 expression in gastric cancer.

Citations

Citations to this article as recorded by

Adjuvant immunotherapy in patients with resected gastric and oesophagogastric junction cancer following preoperative chemotherapy with high risk for recurrence (ypN+ and/or R1): European Organisation of Research and Treatment of Cancer (EORTC) 1707 VESTIG
F. Lordick, M.E. Mauer, G. Stocker, C.A. Cella, I. Ben-Aharon, G. Piessen, L. Wyrwicz, G. Al-Haidari, T. Fleitas-Kanonnikoff, V. Boige, R. Lordick Obermannová, U.M. Martens, C. Gomez-Martin, P. Thuss-Patience, V. Arrazubi, A. Avallone, K.K. Shiu, P. Artru
Annals of Oncology.2024;[Epub] CrossRef
PD-L1 thresholds predict efficacy of immune checkpoint inhibition in first-line treatment of advanced gastroesophageal adenocarcinoma. A systematic review and meta-analysis of seven phase III randomized trials
V. Formica, C. Morelli, L. Fornaro, S. Riondino, M. Rofei, E. Fontana, E.C. Smyth, M. Roselli, H.-T. Arkenau
ESMO Open.2024; 9(11): 103967. CrossRef

Original Articles

Revisiting the utility of identifying nuclear grooves as unique nuclear changes by an object detector model: Pedro R. F. Rende, Joel Machado Pires, Kátia Sakimi Nakadaira, Sara Lopes, João Vale, Fabio Hecht, Fabyan E. L. Beltrão, Gabriel J. R. Machado, Edna T. Kimura, Catarina Eloy, Helton E. Ramos; J Pathol Transl Med. 2024;58(3):117-126. Published online April 30, 2024; DOI: https://doi.org/10.4132/jptm.2024.03.07

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Abstract PDF: Background
Among other structures, nuclear grooves are vastly found in papillary thyroid carcinoma (PTC). Considering that the application of artificial intelligence in thyroid cytology has potential for diagnostic routine, our goal was to develop a new supervised convolutional neural network capable of identifying nuclear grooves in Diff-Quik stained whole-slide images (WSI) obtained from thyroid fineneedle aspiration.
Methods
We selected 22 Diff-Quik stained cytological slides with cytological diagnosis of PTC and concordant histological diagnosis. Each of the slides was scanned, forming a WSI. Images that contained the region of interest were obtained, followed by pre-formatting, annotation of the nuclear grooves and data augmentation techniques. The final dataset was divided into training and validation groups in a 7:3 ratio.
Results
This is the first artificial intelligence model based on object detection applied to nuclear structures in thyroid cytopathology. A total of 7,255 images were obtained from 22 WSI, totaling 7,242 annotated nuclear grooves. The best model was obtained after it was submitted 15 times with the train dataset (14th epoch), with 67% true positives, 49.8% for sensitivity and 43.1% for predictive positive value.
Conclusions
The model was able to develop a structure predictor rule, indicating that the application of an artificial intelligence model based on object detection in the identification of nuclear grooves is feasible. Associated with a reduction in interobserver variability and in time per slide, this demonstrates that nuclear evaluation constitutes one of the possibilities for refining the diagnosis through computational models.

The spectrum of microvascular patterns in adult diffuse glioma and their correlation with tumor grade: Soni , Vaishali Walke, Deepti Joshi, Tanya Sharma, Adesh Shrivastava, Amit Agrawal; J Pathol Transl Med. 2024;58(3):127-133. Published online May 14, 2024; DOI: https://doi.org/10.4132/jptm.2024.03.11

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Abstract PDF: Background
Primary brain tumors constitute the leading cause of cancer-related mortality. Among them, adult diffuse gliomas are the most common type, affecting the cerebral hemispheres and displaying a diffuse infiltrative pattern of growth in the surrounding neuropil that accounts for about 80% of all primary intracranial tumors. The hallmark feature of gliomas is blood vessel proliferation, which plays an important role in tumor growth, tumor biological behavior, and disease outcome. High-grade gliomas exhibit increased vascularity, the worst prognosis, and lower survival rates. Several angiogenic receptors and factors are upregulated in glioblastomas and stimulate angiogenesis signaling pathways by means of activating oncogenes and/or down-regulating tumor-suppressor genes. Existing literature has emphasized that different microvascular patterns (MVPs) are displayed in different subtypes of adult diffuse gliomas.
Methods
We examined the distribution and biological characteristics of different MVPs in 50 patients with adult diffuse gliomas. Haematoxylin and eosin staining results, along with periodic acid–Schiff and CD34 dual-stained sections, were examined to assess the vascular patterns and correlate with different grades of diffuse glioma.
Results
The present observational study on adult diffuse glioma evaluated tumor grade and MVPs. Microvascular sprouting was the most common pattern, while a bizarre pattern (type 2) was associated with the presence of a high-grade glioma. Vascular mimicry was observed in 6% of cases, all of which were grade 4 gliomas.
Conclusions
This study supplements the role of neo-angiogenesis and aberrant vasculature patterns in the grading and progression of adult diffuse gliomas, which can be future targets for planning treatment strategies.

The importance of histomorphological features and ERG expression in the diagnosis of malignancy in cases with atypical small acinar proliferation: Gizem Teoman, Ayten Livaoglu, Hatice Kucuk, Afs ¸ın Rahman Murtezaoglu; J Pathol Transl Med. 2024;58(3):134-140. Published online May 14, 2024; DOI: https://doi.org/10.4132/jptm.2024.03.18

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Abstract PDF: Background
Atypical small acinar proliferation (ASAP) cases typically require rebiopsy, which are invasive and associated with increased risk of complications. Our aim in this study was to determine the importance of laboratory and histological findings and E-26 transformation-specific-related gene (ERG) expression in the diagnosis of malignancy.
Methods
Between March 2016 and March 2022, 84 patients who were diagnosed with ASAP on biopsy or rebiopsy were included in the study. Clinical-laboratory features of age, serum prostate-specific antigen level, and histopathological features were compared and included multifocality, number of suspicious acini, nuclear enlargement, nucleolar prominence, hyperchromasia, cytoplasmic amphophilia, luminal amorphous acellular secretion, crystalloid presence, infiltrative appearance, inflammation, atrophy, α-methyl acyl-CoA racemase, p63, and/or high molecular weight cytokeratin were analyzed. In addition, ERG expression was evaluated immunohistochemically.
Results
Statistically significant correlation was found between nucleolar prominence, nuclear hyperchromasia, crystalloid presence, infiltrative pattern, and prostate cancer (p < .001). In 19 of 84 cases (22.6%) ERG was positive in the nucleus. Prostate cancer was diagnosed at rebiopsy in 15 of the 19 ERG-positive cases (78.9%). A statistically significant correlation was found between ERG positivity and prostate cancer (p= .002).
Conclusions
Our findings suggest that evaluation of these markers during initial transrectal ultrasound biopsies may decrease and prevent unnecessary prostate rebiopsy.

Case Study

Primary epithelioid inflammatory myofibroblastic sarcoma of the brain with EML4::ALK fusion mimicking intra-axial glioma: a case report and brief literature review: Eric Eunshik Kim, Chul-Kee Park, Koung Mi Kang, Yoonjin Kwak, Sung-Hye Park, Jae-Kyung Won; J Pathol Transl Med. 2024;58(3):141-145. Published online May 14, 2024; DOI: https://doi.org/10.4132/jptm.2024.04.12

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Abstract PDF: An aggressive subtype of inflammatory myofibroblastic tumor, epithelioid inflammatory myofibroblastic sarcoma occurs primarily inside the abdominal cavity, followed by a pulmonary localization. Most harbor anaplastic lymphoma kinase (ALK) gene rearrangements, with RANBP2 and RRBP1 among the well-documented fusion partners. We report the second case of primary epithelioid inflammatory myofibroblastic sarcoma of the brain, with a well-known EML4::ALK fusion. The case is notable for its intra-axial presentation that clinico-radiologically mimicked glioma.

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