Claudin-18 as a Promising Surrogate Marker for Endocervical Gastric-type Carcinoma

Gastric-type glandular lesions of the female genital tract excluding the cervix: emerging pathological entities

In the last two decades or so, a spectrum of benign, premalignant and malignant cervical glandular lesions exhibiting gastric differentiation has been described, with gastric-type adenocarcinoma representing the most common human papillomavirus (HPV)-independent cervical adenocarcinoma. More recently, limited literature has reported a variety of gastric-type glandular lesions at other sites within the female genital tract and, as in the cervix (the most common site for these lesions), a spectrum of benign, premalignant and malignant lesions has been proposed. We provide an update and review of the emerging spectrum of gastric-type glandular lesions at female genital tract sites other than the cervix. In the endometrium, putative gastric-type glandular lesions include mucinous metaplasia of gastric-type, atypical mucinous proliferation of gastric-type and gastric-type adenocarcinoma. Similarly in the vagina, gastric-type adenosis, atypical adenosis and adenocarcinoma have been described. There have also been occasional reports of gastric-type lesions involving the ovary and fallopian tube. We provide guidance on how to recognise gastric-type lesions morphologically and immunophenotypically and stress that sometimes these lesions occur at more than one site within the female genital tract (synchronous/multifocal gastric-type lesions of the female genital tract), sometimes in association with Peutz-Jeghers syndrome.

Progress of Clinical Studies Targeting Claudin18.2 for the Treatment of Gastric Cancer

Claudin18.2 is a tight junction protein, highly selective, generally expressed only in normal gastric mucosal epithelial cells, which can effectively maintain the polarity of epithelial and endothelial cells, thus effectively regulating the permeability and conductance of the paracellular pathway. Abnormal expression of Claudin18.2 can occur in various primary malignant tumors, especially gastrointestinal tumors, and even in metastatic foci. It regulates its expression by activating the aPKC/MAPK/AP-1 pathway, and therefore, the Claudin18.2 protein is a pan-cancer target expressed in primary and metastatic lesions in human cancer types. Zolbetuximab (IMAB362), an antibody specific for Claudin18.2, has been successfully tested in a phase III clinical trial, and the results of the study showed that combining Zolbetuximab with chemotherapy notably extends patients' survival and is expected to be a potential first-line treatment for patients with Claudin18.2(+)/HER-2(-) gastric cancer. Here, we systematically describe the biological properties and oncogenic effects of Claudin18.2, centering on its clinical-pathological aspects and the progress of drug studies in gastric cancer, which can help to further explore its clinical value.

Gastric-type adenocarcinoma of the uterine cervix: clinical features and future directions

The concept of gastric-type mucinous carcinoma of the uterine cervix (GAS) has been accepted worldwide because of its aggressive clinical behaviour and the absence of high-risk human papilloma virus infection. The World Health Organization (WHO) 2020 classification divides cervical tumours into two categories: human papilloma virus-associated and human papilloma virus-independent. Hence, GAS is now classified as an human papilloma virus-independent gastric type. Because clinical studies have reported that GAS is refractory to conventional treatments such as chemotherapy and radiotherapy, especially at an advanced stage, and has aggressive features with widespread dissemination to unusual sites, such as the omentum, peritoneum and distant organs, it is urgent to establish new treatment strategies by comparing the molecular profiles of human papilloma virus-associated adenocarcinomas. A series of genetic mutations characteristic to GAS encourage the development of future treatment strategies such as targeted therapy and immunotherapy.

Gastric Type Endocervical Adenocarcinoma With Concurrent High-Grade Squamous Intraepithelial Lesion: A Clinicopathologic Study of Three Patients

OBJECTIVE

We investigate gastric-type endocervical adenocarcinoma (ECA), a prominent HPV-independent adenocarcinoma, and its coexistence with high-grade squamous intraepithelial lesion (HSIL) through the examination of three such tumors.

METHODS

In this study, we conducted an in-depth review of three patients with gastric-type ECA, each associated with high-risk HPV infection as detected on Pap smears. We detailed the clinical and pathological features of each patient and utilized RNAscope for high-risk HPV testing to ascertain HPV status in both gastric-type ECA and HSIL components. Immunohistochemistry with p16, p53, and other biomarkers was also applied.

RESULTS

The gastric-type ECA component, characterized by well-differentiated glands with abundant, clear to eosinophilic cytoplasm, distinct cellular borders, and pale nuclei with conspicuous nucleoli, tested negative for both p16 and high-risk HPV, unlike the concurrent HSIL components which were positive. Additionally, two tumors showed aberrant p53 protein expression in the gastric-type ECA areas, and elevated carbohydrate antigen19-9 levels were noted in two patients. Treatment consisted of total abdominal hysterectomy and bilateral salpingo-oophorectomy, supplemented by chemotherapy and/or radiation, with disease-free intervals of 24, 12, and 40 months post-treatment, respectively.

CONCLUSION

This study highlights the critical need for meticulous diagnostic protocols that combine morphological examination, immunohistochemistry, and HPV RNA in situ hybridization. The rarity of gastric-type ECA coexisting with HPV infection underscores the necessity for continuous research and vigilant monitoring in the field of gynecological oncology.

Current status and molecular biology of human papillomavirus-independent gastric-type adenocarcinoma of the cervix

This article reviews the findings of clinical studies on gastric-type adenocarcinoma of the cervix to date, outline the molecular biological features identified in recent studies, and discusses the future therapeutic strategies. Gastric-type adenocarcinoma of the cervix is a new classification in the World Health Organization 2014 classification. The World Health Organization 2020 classification further divides cervical tumors into two categories: human papillomavirus-associated and human papillomavirus-independent. Thus, gastric-type adenocarcinoma of the cervix is now classified as a human papillomavirus-independent gastric type. Clinical studies have reported that gastric adenocarcinoma of the cervix is refractory to conventional chemotherapy and radiotherapy, and it is desirable to elucidate its molecular biological mechanism. A series of gene mutations characteristic to the gastric-type adenocarcinoma of the cervix encourage the development of future treatment strategies.

Claudin18.2 as a potential therapeutic target for primary ovarian mucinous carcinomas and metastatic ovarian mucinous carcinomas from upper gastrointestinal primary tumours

BACKGROUND

The vast majority of ovarian mucinous carcinomas are metastatic tumours derived from nonovarian primary cancers, typically gastrointestinal neoplasms. Therapy targeting claudin18.2 might be used in gastric, gastroesophageal junction and pancreatic cancers with high expression of claudin18.2. In this study, we aimed to profile the expression of claudin18.2 in primary ovarian mucinous carcinoma (POMC) and metastatic gastrointestinal mucinous carcinoma (MGMC).

METHODS

Immunohistochemistry was used to detect claudin 18.2 expression in whole tissue sections of ovarian mucinous carcinomas, including 32 POMCs and 44 MGMCs, 23 of which were derived from upper gastrointestinal primary tumours and 21 of which were derived from lower gastrointestinal primary tumours. Immunohistochemical studies for claudin18.2, SATB2, PAX8, CK7 and CK20 were performed in all 76 cases.

RESULTS

Among 76 primary and metastatic mucinous carcinomas, claudin18.2 was expressed in 56.6% (43/76) of cases. MGMCs from the upper gastrointestinal tract, including 22 derived from primary stomach tumours and one derived from a pancreas tumour, were positive for claudin 18.2 in 69.5% (16/23) of cases. MGMCs from the lower gastrointestinal tract, including 10 derived from primary appendiceal cancer and 11 derived from colorectal cancers, showed no claudin18.2 expression (0/21). The expression rate of claudin18.2 in primary ovarian mucinous neoplasms, including 22 primary ovarian mucinous carcinomas and 10 primary ovarian borderline mucinous tumours, was 84.4% (27/32). The common immunophenotypic characteristics of POMCs, upper gastrointestinal tract-derived MGMCs, and lower gastrointestinal tract-derived MGMCs were claudin18.2 + /PAX8 + /SATB2- (17/32), claudin18.2 + /PAX8-/SATB2- (16/23) and claudin18.2-/PAX8-/SATB2 + (19/21), respectively.

CONCLUSION

Claudin18.2 is highly expressed in POMCs and MGMCs derived from upper gastrointestinal tract primary tumours; therefore, claudin18.2-targeted therapy might serve as a potential therapeutic strategy for POMCs and MGMCs from the upper gastrointestinal tract.

The role and mechanism of claudins in cancer

Claudins are a tetraspan membrane protein multigene family that plays a structural and functional role in constructing tight junctions. Claudins perform crucial roles in maintaining cell polarity in epithelial and endothelial cell sheets and controlling paracellular permeability. In the last two decades, increasing evidence indicates that claudin proteins play a major role in controlling paracellular permeability and signaling inside cells. Several types of claudins are dysregulated in various cancers. Depending on where the tumor originated, claudin overexpression or underexpression has been shown to regulate cell proliferation, cell growth, metabolism, metastasis and cell stemness. Epithelial-to-mesenchymal transition is one of the most important functions of claudin proteins in disease progression. However, the exact molecular mechanisms and signaling pathways that explain why claudin proteins are so important to tumorigenesis and progression have not been determined. In addition, claudins are currently being investigated as possible diagnostic and treatment targets. Here, we discuss how claudin-related signaling pathways affect tumorigenesis, tumor progression, and treatment sensitivity.

Mucinous Proliferations of the Uterine Corpus: Comprehensive Appraisal of an Evolving Spectrum of Neoplasms

A variety of endometrial lesions may contain mucinous cells. Herein, the author reviews the literature on the classification and clinicopathologic significance of uterine corpus proliferations with a significant mucinous component, assesses the 2020 World Health Organization classification of such lesions, and presents a diagnostic framework. The key epithelial mucinous lesions include mucinous metaplasia, atypical mucinous glandular proliferation and mucinous carcinoma. Each of these categories are classifiable into "usual" and gastrointestinal subtypes, the latter being indicative of intestinal (presence of goblet cells) and/or gastric-type (abundant, pale eosinophilic or clear cytoplasm and well-defined cell borders) morphology. It has been proposed that at least focal expression of gastrointestinal immunohistochemical markers be required for all gastrointestinal type lesions, and for gastrointestinal type atypical mucinous glandular proliferation and carcinoma, minimality or absence of estrogen receptor expression, and the absence of an endometrioid component. Mucinous carcinomas of the usual type, in which >50% of the tumor is comprised of a mucinous component, are the most common. Morphologic subtypes include mucinous carcinoma with microglandular features and mucinous carcinoma with signet rings (signet ring carcinoma). Endometrioid carcinomas with a less than a 50% mucinous component are classified as endometrioid carcinoma with mucinous differentiation. Several studies have directly compared endometrioid and mucinous carcinomas, the latter presumably of the usual type, with respect to patient outcomes after treatment. All have found no difference in overall and disease free survival between these groups. However, three major studies have found mucinous carcinomas to be associated with a higher risk of lymph node metastases. Nineteen cases of mucinous carcinoma of the gastrointestinal type have been reported, and the limited data on their follow-up after primary treatment suggests that this subtype is more clinically aggressive and should accordingly be classified separately from mucinous carcinomas of the usual type. The morphologic spectrum of mucinous carcinoma of the gastrointestinal type is unclear and continues to evolve. Mucinous change, which may sometimes be extensive, may also be associated with papillary proliferation of the endometrium, adenomyoma of the endocervical type, atypical, and typical adenomyomas. In a curettage or biopsy, intestinal type mucinous epithelium may be indicative of any of the gastrointestinal lesions mentioned above, but may also represent samplings of uterine teratomas, yolk sac tumors, genital and extragenital adenocarcinomas with intestinal differentiation, or low-grade appendiceal mucinous neoplasms that secondarily involve the endometrium.

Membranous and nuclear staining of CLDN18 in HPV-independent and HPV-associated endocervical adenocarcinomas

OBJECTIVES

A classification system for endocervical adenocarcinoma (ECA) based on high-risk human papillomavirus (HPV) status has been established; however, the immunohistochemical markers distinguishing HPV-independent and HPV-associated ECAs have not been fully described. Here, we aimed to characterize ECA immunopathological features.

METHODS

We evaluated the immunohistochemical profile of CLDN18, CDX2, PAX8, p16, p53, and CEA in 60 ECAs comprising 10 HPV-independent ECAs and 50 HPV-associated ECAs. Both the membranous and nuclear expression levels of CLDN18 were analyzed.

RESULTS

Membranous CLDN18 (CLDN18 [M]) was found to be expressed in the mucinous epithelium of all HPV-independent ECAs, including eight gastric-type ECAs (G-ECAs), one endometrioid ECA, and one clear cell ECA, but no nuclear CLDN18 (CLDN18 [N]) expression was detected in HPV-independent ECAs. Among HPV-associated ECAs, CLDN18 (M) expression levels in intestinal-type (I-ECAs) and usual-type ECAs (U-ECAs) were significantly different from those in invasive stratified mucin-producing (iSMILE) carcinomas (p = 0.036). Positive CLDN18 (M) staining was present in 55.6% (5/9) of intestinal-type and 39.4% (13/33) of usual-type ECAs and was not present in iSMILE ECAs. Silva pattern C cancers expressed higher levels of CLDN18 (M) than Silva pattern A and B cancers (p = 0.004), whereas the CLDN18 (N) expression levels in cancers showing Silva pattern A were significantly higher than those in cancers exhibiting Silva patterns B and C (p < 0.001).

CONCLUSION

Membranous CLDN18 is expressed in ECAs and is particularly frequently expressed in HPV-independent ECAs, and membranous CLDN18 expression has potential as a therapeutic target. Nuclear staining of CLDN18 is a new immunohistochemical marker for diagnosing Silva pattern A HPV-associated ECAs and is associated with a good prognosis. Further studies should investigate the therapeutic and prognostic significance of membranous and nuclear CLDN18 expression and develop a related test that can be implemented in the clinical evaluation of ECAs.