Mammary Analogue Secretory Carcinoma of Salivary Glands: Molecular Analysis of 25 ETV6 Gene Rearranged Tumors With Lack of Detection of Classical ETV6-NTRK3 Fusion Transcript by Standard RT-PCR: Report of 4 Cases Harboring ETV6-X Gene Fusion

ETV6 Molecular Heterogeneity in Salivary Secretory Carcinoma: A Case Series Report and Literature Review

BACKGROUND

ETV6 gene rearrangement is the molecular hallmark of secretory carcinoma (SC), however; the nature, frequency, and clinical implications of atypical ETV6 signal patterns by fluorescence in situ hybridization (FISH) has not yet been systematically evaluated in salivary gland neoplasms.

METHODS

The clinical, histopathologic, immunohistochemical and molecular features of seven salivary SCs, including four cases with atypical ETV6 FISH patterns, were retrospectively analyzed along with a critical appraisal of the literature on unbalanced ETV6 break-apart in SCs.

RESULTS

The patients were four males and three females (31-70 years-old). Five presented with a painless neck mass and two patients with recurrent disease had a history of a previously diagnosed acinic cell carcinoma of the buccal mucosa. Histologically, there were varied combinations of microcystic, papillary, tubular, and solid patterns. All tumors were diffusely positive for S100 and/or SOX10, while 2 cases also showed luminal DOG1 staining. Rearrangement of the ETV6 locus was confirmed in 5/7 cases, of which 3 cases showed classic break-apart signals, 1 case further demonstrated duplication of the ETV6 5`end and the other loss of one copy of ETV6. Two cases harbored ETV6 deletion without rearrangement. Two of the 4 cases with atypical ETV6 FISH patterns represented recurrent tumors, one with widespread skeletal muscle involvement, bone and lymphovascular invasion. Surgical treatment resulted in gross-total resection in all 7 cases, with a median follow up of 9.5 months post-surgery for primary (n = 3) and recurrent disease (n = 1).

CONCLUSION

Duplication of the distal/telomeric ETV6 probe represented the most common (26/40; 65%) variant ETV6 break-apart FISH pattern in salivary SC reported in the literature and appears indicative of an aggressive clinical course.

Microsecretory adenocarcinoma of the hard palate: a case report and literature review

Microsecretory adenocarcinoma (MSA) is a new type of salivary gland neoplasm identified in the 2022 World Health Organization Classification of Head and Neck Tumour (Skalova et al., Head Neck Pathol 16:40-53, 2022) and is characterized by a unique set of histomorphologic and immunohistochemical features and a recurrent MEF2C::SS18 fusion. MSA was initially misdiagnosed as another salivary gland tumour due to its similar morphology; until recently, only fewer than 50 cases were reported. We present a case of MSA of the hard palate with diverse architectural growth patterns, bland cytological features, abundant basophilic intraluminal secretions and fibromyxoid stroma. The tumour cells were positive for the SOX10, S100, and p63 protein and negative for the p40 protein according to immunohistochemistry. SS18 gene rearrangement was demonstrated via break-apart fluorescence in situ hybridization. We also provided a comprehensive literature review and integrated the clinicopathological features, immunophenotype, and molecular alterations of the disease. A comprehensive understanding of MSA enables us to accurately distinguish and categorize MSA from other salivary gland tumours with analogous morphologies.

Non Indigenous Mammary Secretory Carcinoma of Parotid Gland - An Unusual Presentation

Mammary analog secretory carcinoma (MASC) is a relatively rare, low-grade tumor affecting the salivary glands. We report a 62-year-old female who was diagnosed with MASC of the left parotid gland and underwent left Total conservative parotidectomy with condylectomy and reconstruction with right anterolateral free flap and left facial nerve (frontal branch) reconstruction with a cable graft. As there is no standard treatment protocol developed for the management of MASC, this report focuses on the various management options that have been followed to date.

Characterization of a Molecularly Distinct Subset of Oncocytic Pleomorphic Adenomas/Myoepitheliomas Harboring Recurrent ZBTB47-AS1::PLAG1 Gene Fusion

Recurrent gene fusions are common in salivary gland tumors including benign tumors, such as pleomorphic adenoma (PA) and myoepithelioma (ME). In cases where chromosomal rearrangement is identified in the pleomorphic adenoma gene 1 (PLAG1) gene, different gene partners are found. Oncocytic metaplasia, characterized by oncocytes with abundant eosinophilic granular cytoplasm and hyperchromatic nuclei, is a well-known phenomenon in salivary gland neoplasms. However, the pure oncocytic variant of PA/ME showed PLAG1 gene rearrangements involving various gene partners at the molecular level, without any recurrent fusion being found. Our study includes 20 cases of PA/ME, with 11 females and 9 males. The age of patients ranged from 37 to 96 years, with a median age of 62.8 years. Most tumors originate from the parotid gland. The median size of the tumor was 26.5 mm (range: 13 to 60 mm). Among the 20 cases, 14 were a pure oncocytic variant of PA/ME, whereas 6 cases showed focal oncocytic or oncocytic-like aspects. Molecular studies on 20 cases of PA/ME were conducted. A novel recurrent ZBTB47-AS1::PLAG1 fusion was identified in 6 of 12 cases with pure oncocytic metaplasia, whereas the other cases had PLAG1 gene fusion with different gene partners. The transcriptomic analysis of the cases harboring ZBTB47-AS1::PLAG1 fusion demonstrated that these tumors have a distinct molecular profile from conventional PA/ME. This study reveals a unique subset in the oncocytic PA/ME spectrum characterized by pure oncocytic morphology with larger oncocytic cells and recurrent ZBTB47-AS1::PLAG1 fusion. It also highlights the transcriptomic distinctness of salivary gland adenomas with pure oncocytic metaplasia in the spectrum of salivary gland neoplasms. Further studies are needed to better understand the oncocytic variant of PA/ME and to determine the true nature of oncocytic cells in PA/ME.

Salivary Gland Secretory Carcinoma; Review of 13 Years World-Wide Experience and Meta-Analysis

OBJECTIVES

Secretory Carcinoma is a malignant salivary gland tumor, initially described in 2010. This rare tumor is associated with the translocation t(12;15) (p13;q25), resulting in the fusion gene ETV6-NTRK3. Since this tumor is quite rare, most publications describe only small cohorts of patients. We aimed to investigate the clinical, pathological, and prognostic features of this newly defined malignant entity.

DATA SOURCES

Pubmed, Google Scholar, and Web of Science databases.

REVIEW METHODS

All published articles between 2010 and 2023 were reviewed. Search terms included the terms "Mammary Analogue Secretory Carcinoma" and "Secretory Carcinoma". All articles published in English reporting on Secretory Carcinoma of salivary glands were retrieved.

RESULTS

One-hundred and 12 retrospective articles reporting a total of 674 patients were included, with 52% males and a mean age of 44.9 ± 18.9. The event rate for patients with advanced-stage disease (Stage 3/4) at presentation was 24.1% (95% CI 17.6%-31.9%, I2  = 9.2%), 14.6% for regional metastases (95% CI 10.5%-20%, I2  = 12%), and the event rate of distant metastasis was 8.4% (95% CI 5.5%-12.7%, I2  = 4.2%). Adjuvant radiotherapy was administered for 30.3% of patients (95% CI 24.1%-37.2%, I2  = 21.5%). The recurrence rate was 19% (95% CI 15.1%-23.8%, I2  = 5%). Survival outcomes showed a 17.2% death of disease rate for Secretory Carcinoma patients (95% CI 13.5%-21.8%, I2  = 7.3%).

CONCLUSIONS

Secretory Carcinoma is a rare and relatively newly defined entity arising in the parotid gland most commonly. Characterized as a low-grade tumor, the majority of patients are diagnosed at an early stage, without regional or distant disease, and the prognosis is relatively good.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:1716-1724, 2024.

NTRK Therapy among Different Types of Cancers, Review and Future Perspectives

Neurotrophic tyrosine receptor kinase (NTRK) has been a remarkable therapeutic target for treating different malignancies, playing an essential role in oncogenic signaling pathways. Groundbreaking trials like NAVIGATE led to the approval of NTRK inhibitors by the Food and Drug Administration (FDA) to treat different malignancies, significantly impacting current oncology treatment. Accurate detection of NTRK gene fusion becomes very important for possible targeted therapy. Various methods to detect NTRK gene fusion have been applied widely based on sensitivity, specificity, and accessibility. The utility of different tests in clinical practice is discussed in this study by providing insights into their effectiveness in targeting patients who may benefit from therapy. Widespread use of NTRK inhibitors in different malignancies could remain limited due to resistance mechanisms that cause challenges to medication efficacy in addition to common side effects of the medications. This review provides a succinct overview of the application of NTRK inhibitors in various types of cancer by emphasizing the critical clinical significance of NTRK fusion gene detection. The discussion also provides a solid foundation for understanding the current challenges and potential changes for improving the efficacy of NTRK inhibitor therapy to treat different malignancies.

Diagnostic Utility of Expression Pattern of S100/Mammaglobin/SOX10/DOG 1 Immunohistochemistry in Differentiation of Secretory and Acinic Cell Carcinoma: A Systematic Review and Meta-Analysis

Secretory carcinoma (SC) is a relatively new disease entity, separate from acinic cell carcinoma (AciCC), which frequently displays ETV6-NTRK3 gene fusion. However, the differences between SC and AciCC remain ambiguous. Genetic diversity makes its diagnosis complicated. In this regard combined expression of immunohistochemistry markers S100/Mammaglobin/SOX10 and DOG1 is need of the hour as alternative methodology. The current systematic review was to investigate the diagnostic utility of combined immunohistochemical expression of S100/Mammaglobin/SOX10/DOG1 in distinction of SC from AciCC histologically. An electronic search of databases was carried out using MEDLINE by PubMed, Google scholar, Scopus and Web of science. Articles inclusive of SC and AciCC were assessed with S100/Mammaglobin/SOX10/DOG1 immunohistochemistry and their predominant expression pattern, predictive values, sensitivity and specificity were gathered. Fourteen eligible articles were analysed, which revealed predominant immunostaining pattern of S100 + /Mammaglobin + /SOX10 + /DOG1- by nearly all ETV6::NTRK3 fusion prevalent SCs alongside with other gene fusions like RET, MET and MAML3 with 98.4% sensitivity as well as 86.1% specificity. The evidence supports that S100/Mammaglobin/SOX10/DOG1 combined immunostaining can serve as a reliable diagnostic method to differentiate secretory from acinic cell carcinoma.

The genetic and immune features of salivary gland secretory carcinoma with high-grade transformation

OBJECTIVES

To compare the clinicopathological, molecular, and immune features of conventional and high-grade transformation (HGT) secretory carcinoma (SC) in salivary glands.

MATERIALS AND METHODS

The clinicopathological data of 88 cases including 74 conventional SCs and 14 SCs with HGT were reviewed. Targeted next-generation sequencing was performed in 11 SCs with HGT and 7 conventional SCs. The level of PD-L1 and CD8+ TILs was determined by immunohistochemistry.

RESULTS

Compared with the conventional group, the rates of nodal metastasis, local recurrence, distant metastasis and mortality were significantly higher in the HGT cohort. Mutations of ARID1A/B, KMT2A, HOXD13, NRG1 and ETV6 genes were identified in HGT SCs. A recurrent E307G mutation in GATA6 gene was also observed in two cases. Two deceased HGT patients with distant metastasis harboured NOTCH3 mutations. ETV6-RET translocation was prone to occur in the HGT SCs. Additionally, PD-L1 expression was low, and CD8+ TILs were sparse in most HGT cases.

CONCLUSION

Our findings reveal novel gene alterations involved in the progression of HGT in SCs. Most HGT SCs patients cannot benefit from PD-L1 blocking and may be approached with a distinct treatment strategy including the lymph node dissection and application of molecular target drugs in precision oncology.

Phase separation underlies signaling activation of oncogenic NTRK fusions

NTRK (neurotrophic tyrosine receptor kinase) gene fusions that encode chimeric proteins exhibiting constitutive activity of tropomyosin receptor kinases (TRK), are oncogenic drivers in multiple cancer types. However, the underlying mechanisms in oncogenesis that involve various N-terminal fusion partners of NTRK fusions remain elusive. Here, we show that NTRK fusion proteins form liquid-like condensates driven by their N-terminal fusion partners. The kinase reactions are accelerated in these condensates where the complexes for downstream signaling activation are also concentrated. Our work demonstrates that the phase separation driven by NTRK fusions is not only critical for TRK activation, but the condensates formed through phase separation serve as organizational hubs for oncogenic signaling.

Prevalence and clinico-genomic characteristics of patients with TRK fusion cancer in China

Neurotrophic tyrosine kinase (NTRK) fusions involving NTRK1, NTRK2, and NTRK3 were found in a broad range of solid tumors as driver gene variants. However, the prevalence of NTRK fusions in Chinese solid tumor patients is rarely reported. Based on the next-generation sequencing data from 10,194 Chinese solid tumor patients, we identified approximately 0.4% (40/10,194) of Chinese solid tumor patients with NTRK fusion. NTRK fusions were most frequently detected in soft tissue sarcoma (3.0%), especially in the fibrosarcoma subtype (12.7%). A total of 29 NTRK fusion patterns were identified, of which 11 were rarely reported. NTRK fusion mostly co-occurred with TP53 (38%), CDKN2A (23%), and ACVR2A (18%) and rarely with NTRK amplification (5.0%) and single nucleotide variants (2.5%). DNA-based NTRK fusion sequencing exhibited a higher detection rate than pan-TRK immunohistochemistry (100% vs. 87.5%). Two patients with NTRK fusions showed clinical responses to larotrectinib, supporting the effective response of NTRK fusion patients to TRK inhibitors.

Case Report: A case of complete response to entrectinib in NTRK fusion gene-positive parotid gland cancer

Introduction

Expression of the NTRK gene is rare in solid tumors but is highly prevalent in salivary gland secretory carcinomas. Here, we report a case of a complete response to entrectinib in a patient with NTRK fusion gene-positive parotid carcinoma.

Case description

The patient was a 44-year-old man who underwent total left parotidectomy and left cervical lymph node dissection for a left parotid tumor at 24 years of age. The histopathological diagnosis was mammary analog secretory carcinoma. Postoperatively, the patient received only radiation therapy. Sixteen years after the surgery, the patient became aware of a mass in the left parotid region. A close examination revealed local recurrence and multiple cervical lymph node metastases. S-1 monotherapy was started as chemotherapy but was discontinued 3 years later because of disease progression. As there was no standard treatment, a comprehensive genomic profiling test using a next-generation sequencer was performed, and the ETV6-NTRK3 fusion gene was identified. Entrectinib, an NTRK inhibitor, was immediately administered at a dose of 600 mg/day. The local recurrence rapidly shrank grossly from the beginning of treatment, and a complete response was observed 6 months later. However, creatinine levels exhibited an increase at week 68 of treatment; consequently, entrectinib dosage was lowered to 400 mg/day, leading to an immediate improvement in creatinine levels. Entrectinib was associated with additional side effects, including dysgeusia, fatigue, dizziness, and weight gain, all of which were also alleviated by the reduction in entrectinib dose. Thirty months after treatment initiation, the patient maintained a complete response and continued to receive entrectinib.

Conclusion

The NTRK fusion gene should always be checked in the presence of salivary gland secretory carcinoma.

Identification of Chimeric NTRK3 Genes in Papillary Thyroid Cancer Cells by Analyzing the Imbalance of the Expression of 5' and 3' mRNA Fragments

The standard for detecting chimeric genes of neurotrophic receptor tyrosine kinases (NTRK) is next generation sequencing (NGS). However, this analysis is expensive and takes several days. As a rapid screening method for the detection of NTRK3-dependent papillary thyroid cancer, an analysis of the expression imbalance between 5' and 3' NTRK3 mRNA fragments was used (5'/3' RT-PCR). The reference method for detection of NTRK3 rearrangements was fluorescent in situ hybridization (FISH), and the most frequent rearrangements in papillary thyroid cancer were tested using reverse transcription PCR (RT-PCR). Using 5'/3' RT-PCR, 18 samples of papillary thyroid cancer carrying chimeric transcripts of NTRK3 mRNA were detected. The sensitivity of the developed technique was 88.9% and specificity was 99.3%. Thus, a fast and cost-effective method of screening samples of papillary thyroid cancer in paraffin blocks is proposed with acceptable sensitivity and specificity.

Salivary Gland Secretory Carcinoma: Clinicopathologic and Genetic Characteristics of 215 Cases and Proposal for a Grading System

Salivary gland secretory carcinoma (SC), previously mammary analog SC, is a low-grade malignancy characterized by well-defined morphology and an immunohistochemical and genetic profile identical to SC of the breast. Translocation t(12;15)(p13;q25) resulting in the ETV6 :: NTRK3 gene fusion is a characteristic feature of SC along with S100 protein and mammaglobin immunopositivity. The spectrum of genetic alterations for SC continues to evolve. The aim of this retrospective study was to collect data of salivary gland SCs and to correlate their histologic, immunohistochemical, and molecular genetic data with clinical behavior and long-term follow-up. In this large retrospective study, we aimed to establish a histologic grading scheme and scoring system. A total of 215 cases of salivary gland SCs diagnosed between 1994 and 2021 were obtained from the tumor registries of the authors. Eighty cases were originally diagnosed as something other than SC, most frequently acinic cell carcinoma. Lymph node metastases were identified in 17.1% (20/117 cases with available data), with distant metastasis in 5.1% (6/117). Disease recurrence was seen in 15% (n=17/113 cases with available data). The molecular genetic profile showed ETV6 :: NTRK3 gene fusion in 95.4%, including 1 case with a dual fusion of ETV6 :: NTRK3 and MYB :: SMR3B . Less frequent fusion transcripts included ETV6 :: RET (n=12) and VIM :: RET (n=1). A 3-tiered grading scheme using 6 pathologic parameters (prevailing architecture, pleomorphism, tumor necrosis, perineural invasion (PNI), lymphovascular invasion (LVI), and mitotic count and/or Ki-67 labeling index) was applied. Grade 1 histology was observed in 44.7% (n=96), grade 2 in 41.9% (n=90), and grade 3 in 13.5% (n=29) of cases. Compared with low-grade and intermediate-grade SC, high-grade tumors were associated with a solid architecture, more prominent hyalinization, infiltrative tumor borders, nuclear pleomorphism, presence of PNI and/or LVI, and Ki-67 proliferative index >30%. High-grade transformation, a subset of grade 2 or 3 tumors, seen in 8.8% (n=19), was defined as an abrupt transformation of conventional SC into high-grade morphology, sheet-like growth, and a tumor lacking distinctive features of SC. Both overall survival and disease-free survival (5 and 10 y) were negatively affected by tumor grade, stage, and TNM status (each P <0.0001). SC is a low-grade malignancy with predominantly solid-microcystic growth patterns, driven by a gene fusion, most commonly ETV6 :: NTRK3 . There is a low risk for local recurrence and a good overall long-term survival, with a low risk for distant metastasis but a higher risk for locoregional lymph node metastasis. The presence of tumor necrosis, hyalinization, PNI and/or LVI, and positive resection margins correlate with higher tumor grade, less favorable prognosis, and increased mortality. The statistical results allowed us to design a 3-tiered grading system for salivary SC.

NTRK fusions in solid tumours: what every pathologist needs to know

Fusions involving the Neurotrophic tropomyosin receptor kinase (NTRK) gene family (NTRK1, NTRK2 and NTRK3) are targetable oncogenic alterations that are found in a diverse range of tumours. There is an increasing demand to identify tumours which harbour these fusions to enable treatment with selective tyrosine kinase inhibitors such as larotrectinib and entrectinib. NTRK fusions occur in a wide range of tumours including rare tumours such as infantile fibrosarcoma and secretory carcinomas of the salivary gland and breast, as well as at low frequencies in more common tumours including melanoma, colorectal, thyroid and lung carcinomas. Identifying NTRK fusions is a challenging task given the different genetic mechanisms underlying NTRK fusions, their varying frequency across different tumour types, complicated by other factors such as tissue availability, optimal detection methods, accessibility and costs of testing methods. Pathologists play a key role in navigating through these complexities by determining optimal approaches to NTRK testing which has important therapeutic and prognostic implications. This review provides an overview of tumours harbouring NTRK fusions, the importance of identifying these fusions, available testing methods including advantages and limitations, and generalised and tumour-specific approaches to testing.

Secretory carcinoma of minor salivary glands of buccal mucosa: A case report and review of the literature

INTRODUCTION AND IMPORTANCE

Secretory carcinoma (SC) is an uncommon salivary gland neoplasm of the oral cavity that microscopically may mimic acinic cell carcinoma (ACC) and mucoepidermoid carcinoma (MEC). Secretory carcinoma (SC) of the salivary gland has been recently added in fourth edition of the head and neck world health organization. Most of these tumors are located on the parotid gland with very few cases reported in the minor salivary glands of the buccal mucosa. This work has been reported in line with the SCARE criteria.

PRESENTATION OF CASE

A 42 years old hypertensive male, shop keeper by occupation, with no prior addiction history, no dental extraction or trauma, presented with complaint of nodular lesion on left buccal mucosa for five years. On Clinical examination, adequate mouth opening, dentulous patient with 2.4 × 2 cm well circumscribed, nodular, non-tender, benign looking lesion was observed on left buccal mucosa near upper alveolus. Overlying mucosa appeared normal with no clinically palpable cervical lymphadenopathy. Histopathology revealed salivary gland neoplasm favoring secretory carcinoma. MRI scan showed lobulated enhancing nodular lesion arising from left buccal mucosa of size 2.3 ∗ 1.3 ∗ 1.7 cm, close to left superior alveolus without involving any cortical areas of marrow infiltration, with bilateral symmetrical level IIa reactive cervical nodes. Wide local excision and ipsilateral selective neck dissection [level 1, 2, 3] was done. Post-operative period was smooth with no complain of paresthesia observed. The final histopathology report showed secretory carcinoma. Two out of six lymph nodes from level I were positive for metastatic carcinoma with no extra nodal extension. Final stage of the tumor was pT1N2bMx. Patient underwent post-operative adjuvant radiotherapy for period of 6 weeks, received total 30 fractions and total dose of 6000 centigray.

CLINICAL DISCUSSION

SC behaved clinically an indolent being painless and having long duration of symptoms with normal overlying mucosa. But histopathologically there was cervical node metastasis. That changed final staging and added adjuvant treatment for this patient. The discrepancy in clinical and pathological diagnosis might be due to the indolent clinical behavior of SC arising in the minor salivary gland of buccal mucosa. In the present case, the absence of zymogen granules and presence of microcytic pattern with eosinophilic cytoplasm and eosinophilic secretory material were suggestive of SC.

CONCLUSION

This case report represents a rare case of SC of minor salivary glands of buccal mucosa, which was indolent as per clinical presentation but on final histopathological report it had cervical nodal metastasis that changed the final stage of the disease, for which adjuvant radiotherapy was needed. Although Secretory carcinomas are generally considered having a favorable prognosis and are regarded as low- grade carcinomas with limited number of recurrence and cervical nodal metastasis, but sometimes they do metastasize to cervical nodes for which accurate and timely intervention in the form of neck dissection may be performed to establish final staging and start additional treatment modality if required for better outcome of the disease.

Japanese Society of Medical Oncology/Japan Society of Clinical Oncology/Japanese Society of Pediatric Hematology/Oncology-led clinical recommendations on the diagnosis and use of tropomyosin receptor kinase inhibitors in adult and pediatric patients with neurotrophic receptor tyrosine kinase fusion-positive advanced solid tumors

BACKGROUND

Clinical trials have reported the efficacy of tropomyosin receptor kinase (TRK) inhibitors against neurotrophic receptor tyrosine kinase (NTRK) fusion gene-positive advanced solid tumors. The accumulated evidence of tumor-agnostic agent has made since TRK inhibitors were approved and used in clinical practice. Therefore, we have revised the 'Japan Society of Clinical Oncology (JSCO)/Japanese Society of Medical Oncology (JSMO)-led clinical recommendations on the diagnosis and use of tropomyosin receptor kinase inhibitors in adult and pediatric patients with neurotrophic receptor tyrosine kinase fusion-positive advanced solid tumors, cooperated by the Japanese Society of Pediatric Hematology/Oncology (JSPHO)'.

METHODS

Clinical questions regarding medical care were formulated for patients with NTRK fusion-positive advanced solid tumors. Relevant publications were searched by PubMed and Cochrane Database. Critical publications and conference reports were added manually. Systematic reviews were performed for each clinical question for the purpose of developing clinical recommendations. The committee members identified by JSCO, JSMO, and JSPHO voted to determine the level of each recommendation considering the strength of evidence, expected risks and benefits to patients, and other related factors. Thereafter, a peer review by experts nominated from JSCO, JSMO, and JSPHO, and the public comments among all societies' members was done.

RESULTS

The current guideline describes 3 clinical questions and 14 recommendations for whom, when, and how NTRK fusion should be tested, and what is recommended for patients with NTRK fusion-positive advanced solid tumors.

CONCLUSION

The committee proposed 14 recommendations for performing NTRK testing properly to select patients who are likely to benefit from TRK inhibitors.

A Parotid Gland Mammary Analogue Secretory Carcinoma in a 4-Year-Old Boy: Case Report and Literature Review

Background: Mammary analogue secretory carcinoma (MASC) is characterized by similar histologic, immunohistochemical, and molecular features with breast secretory carcinoma. MASC usually occurs in adults. Case report: A 4-year-old boy presented with a right infra-auricular mass. Features of the tumor include solid, tubular, and papillary growth patterns, with homogenous eosinophilic secretions inside microcystic structures. Immunohistochemical stains showed strong, diffuse staining for CK7, S100, pan-TRK protein. P63 was positive in a peripheral pattern. Fluorescence in situ hybridization (FISH) analysis showed the characteristic ETV6-NTRK3 gene fusion. Conclusion: Typical histological, immunohistochemical, and molecular features are present in MASC occurring early in childhood.

Molecular identification of an ETV6-RET fusion in a secretory carcinoma associated with a pleomorphic adenoma

Pleomorphic adenoma (PA) is the most common neoplasm of the salivary glands. Although several carcinomas have been reported to arise from PA, only 1 case of salivary gland secretory carcinoma (SC) ex pleomorphic adenoma has been previously reported. SC is a newly described salivary gland tumor harboring an ETV6-NTRK3 translocation, which is classically observed in secretory carcinoma of the breast, although other translocations have recently been observed. We report the first case of the molecular identification of a rare ETV6-RET translocation in an SC arising from a PA in the submandibular salivary gland (SC ex PA). Our results add to the diversity of tumors that are associated with PA and contribute to the molecular characterization of SC, which will have implications on its diagnosis, prognosis, and treatment.

Advancement of secretory breast carcinoma: a narrative review

BACKGROUND AND OBJECTIVE

Secretory breast carcinoma (SBC) is a rare breast malignancy. Most available studies on SBC are case reports or small case series, and the few large-sample studies available lack critical information due to database limitations. To improve the understanding of SBC and provide a reference for clinical practice, we systematically reviewed the demographic, clinical, pathologic, and genetic characteristics of SBC, as well as its treatment and prognosis.

METHODS

We conducted a PubMed search with the keywords "secretory breast carcinoma" or "juvenile breast carcinoma". Relevant English-language publications published from January 1966 to February 2022 were screened manually at 3 levels-title, abstract, and full text-to identify the articles that presented the demographic, clinical, pathologic, and genetic characteristics of SBC, as well as its treatment and prognosis.

KEY CONTENT AND FINDINGS

SBC lacks specific clinical manifestations and has typical pathological and molecular characteristics, including intracellular and extracellular eosinophilic secretions, immune spectrum similar to hormone receptor-positive tumors, and the ETV6-NTRK3 fusion gene. Surgery remains the primary treatment for SBC. Postoperative radiotherapy is recommended by most researchers for adult SBC but not for pediatric patients. The evidence of chemotherapy and endocrine therapy is insufficient, and targeted therapy of the ETV6-NTRK3 fusion gene shows a good response. Most patients with SBC have a good prognosis except for a few patients who experience distant metastases. Future studies will be focused on the molecular characteristics of those patients with SBC who have a poor prognosis.

CONCLUSIONS

The development of histopathology and molecular genetics has promoted the progress of the clinical diagnosis of SBC. The purpose of this review is to serve as a guide for the better clinical treatment of SBC, particularly in the areas of disease identification and prognosis classification for patients.

Secretory carcinoma of the salivary gland: a multi-institutional clinicopathologic study of 90 cases with emphasis on grading and prognostic factors

Secretory carcinoma (SC) is a rare form of salivary carcinoma that was first described in 2010 and is characterized by ETV6::NTRK3 fusion in most cases. In this large retrospective study, we aimed to identify adverse clinicopathologic factors and propose a prognostically relevant grading scheme for SC.

METHODS

A detailed clinicopathologic review was conducted on 90 SCs from the major and minor salivary glands.

RESULTS

The median age at presentation was 50 years (range: 7-93). Sixty-nine (77%) tumours originated from major salivary glands, whereas the remaining 21 involved minor salivary glands.Six cases (7%) had cervical nodal metastasis. Only lymphovascular invasion (LVI) was associated with a risk of nodal metastasis (P < 0.05). The 5-year disease-specific survival and disease-free survival (DFS) were 98% and 87%, respectively. On univariate survival analysis, adverse prognostic factors associated with decreased DFS included minor salivary gland origin, atypical mitosis, high mitotic index, high-grade transformation (HGT), necrosis, nuclear pleomorphism, infiltrative tumour border, fibrosis at the invasive front, LVI, positive margin, and advanced pT stage (P < 0.05). When adjusted for pT stage and margin status, mitotic index, LVI, nuclear pleomorphism, and HGT remained as independent prognostic factors.

CONCLUSION

We therefore propose a two-tiered grading system for SC. The low-grade SC is defined as those with <5 mitoses /10 high-power fields and no tumour necrosis, and high-grade SC as those with ≥5 mitoses /10 high-power fields and/or necrosis. This proposed grading system can be useful to risk stratify patients with SC for appropriate clinical management.

Treatment Patterns of Real-World Patients with TRK Fusion Cancer Treated by US Community Oncologists

BACKGROUND

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are present across various tumor types with an estimated overall prevalence of less than 1%. Tropomyosin receptor kinase inhibitors (TRKis) block the constitutively activated tyrosine receptor kinase (TRK) fusion protein produced in cancers with NTRK gene fusions (NTRK+) from downstream signaling. Many treatment guidelines now include TRKis as first-line (1L) or subsequent treatment options for TRK fusion cancer.

OBJECTIVE

This study aimed to assess treatment patterns subsequent to a finding of NTRK+ status among patients with TRK fusion cancer.

PATIENTS AND METHODS

This was a one-time, retrospective, multi-site patient chart abstraction by oncology practices in the USA from June to September 2020. US medical oncologists from the Oncology Provider Extended Network (OPEN) who had treated patients with NTRK+ advanced/metastatic solid tumors abstracted information into electronic case report forms (eCRFs) for adult patients with advanced/metastatic solid tumors and a NTRK+ tumor test result with a known fusion partner. Data abstracted into eCRFs by oncologists included demographic, clinical, and treatment characteristics of patients with advanced/metastatic TRK fusion solid tumors. Responses were summarized using descriptive statistics. Median treatment durations across the lines of therapy were estimated by Kaplan-Meier time to discontinuation.

RESULTS

A total of 19 medical oncologists abstracted data from 110 patient charts. Median patient age at advanced/metastatic diagnosis was 62 years. The majority of patients were male (58.2%) and White (79.1%). Solid tumor types reported in at least 10% of the study cohort were lung (24.5%), cholangiocarcinoma (13.6%), pancreatic (10.9%), and colorectal (10.0%). Results for patients with hepatobiliary cancers (i.e., cholangiocarcinoma, pancreatic cancer, hepatocellular carcinoma) and colorectal cancer, and appendiceal cancer are also included. Median duration of 1L TRKi therapy was 16.8 months across all solid tumor types, whereas median duration of 1L was 5.6 months among patients receiving non-TRKi therapies (p = 0.017). Among the solid tumor types represented by at least 10% of the study population, median duration of 1L TRKi therapy was only reached in patients with pancreatic cancer (3.3 months). Median duration of TRKi in the second-line (2L) setting was 7.9 months overall, relative to 5.3 months among patients receiving non-TRKi therapies (p = 0.003). Across lung, cholangiocarcinoma, pancreatic, and colorectal cancers, the median durations of 2L TRKi therapy were 14.1, 6.0, 6.1, and 4.1 months, respectively.

CONCLUSION AND RELEVANCE

Among patients with advanced/metastatic TRK fusion solid tumors, medical oncologists reported that approximately two-thirds initiated a TRKi during the study period. Treatment with a TRKi was longer in duration compared to non-TRKi treatment in 1L and 2L therapy. Additional research is needed to gain insight into the association between early TRKi therapy initiation and clinical outcomes in the real-world setting.

Secretory Carcinoma of the Salivary Gland: A Rarity in Children

Originally described as mammary analog secretory carcinoma (SC), SC of the salivary gland is a rare malignancy with morphologic and molecular similarities to SC of the breast. We present 2 children with salivary gland SC with the classic ETV6-NTRK3 gene fusion, including 1 with lymph node metastases. Both patients underwent surgical resection and were in remission 24 months postsurgery. One patient was additionally found to have synchronous papillary thyroid carcinoma with a TFG-MET fusion. A review of published cases highlights the expanding molecular profile and confirms the favorable course of salivary gland SC after surgical resection.

NTRK Fusion in Non-Small Cell Lung Cancer: Diagnosis, Therapy, and TRK Inhibitor Resistance

Neurotrophic tropomyosin receptor kinase (NTRK) gene fusion has been identified as an oncogenic driver of various solid tumors, and it is rare in non-smalll cell lung cancer (NSCLC) with a frequency of approximately less than 1%. Next-generation sequencing (NGS) is of priority for detecting NTRK fusions, especially RNA-based NGS. Currently, the tropomyosin receptor kinase (TRK) inhibitors have shown promising efficacy and well tolerance in patients with NTRK fusion-positive solid tumors, regardless of tumor histology. The first-generation TRK inhibitors (larotrectinib and entrectinib) are recommended as the first-line treatment for locally advanced or metastatic NSCLC patients with positive NTRK fusion. However, TRK inhibitor resistance can eventually occur due to on-target or off-target mechanisms. Further studies are under investigation to overcome resistance and improve survival. Interestingly, NTRK fusion might be the mechanism of resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKI) in NSCLC patients with EGFR mutation. Regarding immunotherapy, the efficacy of immune checkpoint inhibitors in NSCLC patients harboring NTRK fusion has yet to be well described. In this review, we elucidate the function of NTRK genes, summarize the diagnostic techniques for NTRK fusions, and present clinical data for TRK inhibitors; we also discuss potential mechanisms of resistance to TRK inhibitors.

The evolving role of molecular pathology in the diagnosis of salivary gland tumours with potential pitfalls

Salivary gland tumors are diagnostically challenging owing to the morphological diversity within any tumor type and overlapping histomorphology and immunohistochemistry amongst different tumours. In past two decades, rapid progress has been made in the field of understanding the pathogenesis of these tumours with the discovery of many tumour specific translocations and rearrangements. This includes CRTC1-MAML2 and CRTC-MAML2 in mucoepidermoid carcinoma, MYBNFIB and MYBL1-NFIB fusions in adenoid cystic carcinoma, PLAG1 and HMGA2 in pleomorphic adenoma, ETV6-NTRK3 in secretory carcinoma, NR4A3 rearrangements in acinic cell carcinoma, PRKD1 mutations in polymorphous adenocarcinoma and EWSR1-ATF1 in clear cell carcinoma. This review is a lens for progress made till date in the molecular pathology of salivary gland tumours with a special focus on their role as diagnostic tools and implications on clinical management of the patient as prognostic and predictive markers.

Prognostic factors in mammary analogue secretory carcinomas of the parotid gland: Systematic review and meta-analysis

Mammary analogue secretory carcinomas (MASCs) of the parotid gland are considered as low-grade malignancies with good clinical outcome but lacking data regarding prognostic factors. We performed meta-analysis assessing prognostic factors for disease-free survival (DFS) and overall survival (OS) in 256 patients with MASCs of the parotid gland. A total of 73 studies have met the inclusion criteria and 76.3% of patients were seen with T1 and T2 tumors and negative neck nodes. Lymph node metastasis (57.4%) and distant recurrences (46.2%) were particularly found in T4 tumors (p < 0.001). DFS at 5 and 10 years was 77.9% and 47.2% compared to 88.1% and 77.2% for OS at the same time points. Male sex, T3-T4 tumors, and recurrent disease represented independent worse prognosticators for survival outcome. Altogether, parotid gland MASCs show good long-term outcome, but T4 tumors behave significantly more aggressive and require extended treatment strategies along with close follow-ups.

Diagnosis and treatment of secretory carcinoma arising from the oral minor salivary gland: Two case reports

INTRODUCTION

Secretory carcinoma (SC) is a malignancy of the salivary glands, which is similar to SC of the breast regarding its association with neurotrophic tyrosine receptor kinase fusion-positive gene. SC is a recently described salivary gland tumor, and there are a few reports describing oral minor salivary gland-derived SC. We reported two cases of SC in the oral cavity and reviewed the literature.

PATIENT CONCERNS

The patients included a 65-year-old Japanese woman who presented with a mass of the upper lip and an 84-year-old Japanese man who presented with a mass on the buccal mucosa.

DIAGNOSIS

Diagnosis was based on histomorphological and immunohistochemical findings and identification of a specific translocation of the ETS variant 6-neurotrophic receptor tyrosine kinase 3 gene fusion. Case 1 was finally diagnosed using reverse transcription-polymerase chain reaction with formalin-fixed paraffin-embedded tissue samples, while case 2 was diagnosed using fluorescence in situ hybridization analysis.

INTERVENTIONS AND OUTCOMES

In case 1, excisional biopsy was done and there was no recurrence observed in five-year follow-up. In case 2, tumor resection was done and there was no recurrence observed in two-year follow-up.

CONCLUSION

It is highly likely for many cases of SC to be initially diagnosed as acinic cell carcinoma (AciCC) owing to their similar histological findings. The treatment strategy for minor salivary gland-originated SC is similar to that of AciCC; however, SC is often highly malignant and involves a high risk of cervical lymph node metastasis. Thus, establishing an accurate diagnosis together with pathologists and confirming the presence of the ETS variant 6-neurotrophic receptor tyrosine kinase 3 fusion gene using genetic analysis is important.

NTRK-Rearranged soft tissue neoplasms: A review of evolving diagnostic entities and algorithmic detection methods

The spectrum of tumors with NTRK1/2/3 rearrangements has expanded with widespread use of next generation sequencing (NGS) technology. For many years it was known that a majority of infantile fibrosarcomas (IFS), and their counterpart in the kidney, cellular congenital mesoblastic nephroma, contain the recurrent ETV6-NTRK3 fusion. Sequencing RNA transcripts from IFS and their morphologically similar counterparts in older children and adults has shown rearrangements with other 5' partners combined with NTRK1, NTRK2, and NTRK3 can also occur. For those tumors occurring outside of the infant age group, this has resulted in a proposed new diagnostic entity of "NTRK-rearranged spindle cell neoplasm." The clinical behavior of NTRK rearranged soft tissue tumors varies, though most show localized disease with rare metastases. The pathology of NTRK rearranged tumors exists on a spectrum, with overlapping features of classic infantile fibrosarcoma, lipofibromatosis, and malignant peripheral nerve sheath tumor. In this tumor spectrum, clinical and pathologic predictive factors are largely still to be determined, with no clear association between histologic grade and severity of disease. Of critical importance is detection of the NTRK rearrangement in order to guide treatment in patients with unresectable and metastatic disease. While resection is the definitive treatment, these tumors do show response to targeted TRK kinase inhibitors. Multiple detection methods are available, including immunohistochemistry, FISH, and next generation sequencing, which each have their merits and potential pitfalls. We aim to review the clinical characteristics and histomorphology of mesenchymal tumors with NTRK rearrangements as well as discuss molecular detection methods and diagnostic algorithms specific for soft tissue tumors.

A systematic review of secretory carcinoma of the salivary gland: where are we?

OBJECTIVE

The aim of this systematic review was to describe the epidemiology, diagnostic criteria, differential diagnosis, treatment, prognostic factors, and treatment outcomes of secretory carcinoma.

STUDY DESIGN

A comprehensive search of Lilacs, PubMed, Science Direct, and Web of Science databases was conducted to identify all case reports, letter to the editor, and histopathologic reclassifications regarding salivary gland secretory carcinoma published in English, Spanish, French, and Portuguese.

RESULTS

The final analysis included 119 studies, which totaled 642 secretory carcinoma diagnoses, with 239 case reports and 403 diagnostic reclassifications, mostly in the United States. The age range was 5 to 87 years, and cases were predominantly in males (58.7%) and mostly affecting the parotid glands (73.7%). The disease usually presents as a slow-growing, painless mass. The main differential diagnosis is acinic cell carcinoma, and the tumor is usually treated with surgery. The prognosis is considered favorable, although there have been reports of local recurrences, distant metastases, and deaths.

CONCLUSIONS

It is important that clinicians become aware of this salivary gland neoplasm and report clinical data, clinical course, management and long-term follow-up. There is an urgent need to conduct more clinical trials, especially on tropomyosin receptor kinase (TRK) inhibitors and other potential target therapy modalities.

[Multidisciplinary consensus on optimizing the detection of NTRK gene alterations in tumours]

The recent identification of rearrangements of neurotrophic tyrosine receptor kinase (NTRK) genes and the development of specific fusion protein inhibitors, such as larotrectinib and entrectinib, have revolutionized the diagnostic and clinical management of patients presenting with tumours with these alterations. Tumours that harbour NTRK fusions are found in both adults and children and are either rare tumours with common NTRK fusions that may be diagnostic, or more common tumours with rare NTRK fusions. To assess the currently available evidence, 3key Spanish medical societies (the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Pathology (SEAP) and the Spanish Society of Paediatric Haematology and Oncology (SEHOP) have brought together a group of experts to develop a consensus document that includes guidelines on the diagnostic, clinical and therapeutic aspects of NTRK-fusion tumours. It also discusses the challenges related to the routine detection of these genetic alterations in a mostly public health care system.

Secretory Carcinoma of the Salivary Gland - Systematic Review of the Literature and Report of 2 Cases

PURPOSE

Secretory carcinoma (SC) of the salivary gland, formerly known as mammary analogue secretory carcinoma, is an uncommon and fairly newly described low grade malignant neoplasm of the salivary gland. Given the small number of cases reported in the literature to date, treatment guidelines are scarce. This study aimed to describe the clinical characteristics of SC, discuss prior management strategies, and provide recommendations for future treatment.

METHODS

We performed a systematic review of all the cases of SC reported in the literature since it was first recognized in 2010. Using Pubmed, Crossref, and Google Scholar, we identified all articles reporting cases of SC.

RESULTS

We identified 657 cases of SC in 109 articles. In addition, we provided 2 new cases, for a total of 659 cases in 110 articles. To our knowledge, this is the largest review of cases of SC in the literature to date. We summarized the clinical characteristics of SC, as well as the nodal status, clinical management, recurrence rate, and death rate.

CONCLUSIONS

SC occurs on average in middle age (with a large age range), presents most often initially as localized disease without metastasis, and has a low but not insignificant recurrence rate. Deaths have been reported. The generalized recommendations for treatment of SC are in line with those of other low-grade salivary gland malignancies.

Clinicopathologic and Molecular Characterization of Four Cases of Pediatric Salivary Secretory Carcinoma (SSC), One with ETV6-RET Fusion

Salivary gland secretory carcinoma (SSC) is a neoplasm with characteristic histologic features, similar to those of secretory carcinoma of the breast. Only a few pediatric SSC cases have been reported, all with ETV6-NTRK3 fusion. We present four new pediatric SSC examples, one with a novel ETV6-RET fusion. Four cases of SSC were diagnosed between 2010 and 2020: 2 boys, 7 and 9 year-old with parotid tumors (1.5 and 1.3 cm, respectively); and two 14 year-old girls: one with a submandibular tumor (2.1 cm), and one with a parotid lesion (1.2 cm). Histologically, all tumors were similar: well-circumscribed lesions composed by mid-size, monotonous cells with eosinophilic and sometimes vacuolated cytoplasm. The nuclei are oval to round with open chromatin and a single nucleolus. There are duct-like structures and microcysts with colloid-like material. Immunohistochemically, tumor cells are positive for S100, CK7, mammaglobin and GATA3. A classic ETV6-NTRK3 translocation was confirmed in the three parotid tumors; an ETV6-RET fusion was demonstrated in the submandibular lesion. All patients underwent complete surgical resection and are alive without tumor recurrence after a follow-up time ranging from one to 4 years. Pediatric SSC is extremely rare but their characteristic morphology and immunohphenotype facilitate their diagnosis. We describe the first pediatric case with the recently reported ETV6-RET fusion. Similar to adult cases, this tumor is morphologically undistinguishable from those carrying the classic ETV6-NTRK3 translocation. Thus, in pediatric cases with morphology suggestive of SSC and negative ETV6-NTRK3 by RT-PCR, other possible fusions should be investigated.

A case of "ETV6-FISH-negative" secretory carcinoma of the parotid gland: immunohistochemical study

Secretory carcinoma of the salivary glands is a relatively new disease concept, and is characterized by "morphological resemblance to mammary secretory carcinoma and ETV6-NTRK3 gene fusion." Herein we describe a confusing case and briefly discuss practical diagnostic problems. The patient was a 71-year-old Japanese man who had a tumor consistent with secretory carcinoma at the microscopic and immunohistochemical levels. Immunohistochemically, EMA and S100 protein were noted to be positive along with various cytokeratins as well as mammaglobin and pSTAT5. Moreover, vimentin was focally positive. Smooth muscle actin, p63, p40, and androgen receptor were negative. However, a search using fluorescence in situ hybridization did not reveal a definite split signal for the ETV6 gene. It is presumed that confirming the diagnosis of secretory carcinoma without genetic retrieval will be accepted as a diagnostic method, and we hope that worldwide general recognition may earlier reach "gradual acceptance."

The potential targeted drugs for fusion genes including NRG1 in pancreatic cancer

Pancreatic cancer (PC) remains an incurable disease with few treatment options Recently, promising targets have been identified and novel therapeutic drugs are currently under development in KRAS wild-type PC. It has been reported that KRAS wild-type PC has the genomic alterations such as oncogenic derivers and kinase fusions. NRG1 fusion, which encodes the neuregulin 1 and is the main ligands for ERRB3, has been identified in approximately half of younger patients with PC with KRAS wild-type tumors by RNA sequencing. There are several promising targeted therapies for NRG1 fusion-positive tumors, such as EGFR-tyrosine kinase inhibitor, HER3, HER2 antibodies. BRAF, NTRK, and ALK fusion are also potentially actionable alterations in KRAS wild-type PC and novel therapies targeting certain aberrations have shown activity in clinical trials.

Characterization of an ETV6-NTRK3 rearrangement with unusual, but highly significant FISH signal pattern in a secretory carcinoma of the salivary gland: a case report

BACKGROUND

Fusions of neurotrophic tropomyosin receptor kinase genes NTRK1, NTRK2 and NTRK3 with various partner genes occur in both common and rare tumours and are of paramount predictive value due to the availability of very effective pan-Trk inhibitors like Larotrectinib and Entrectinib. Detection of NTRK fusions is mainly performed by fluorescence in situ hybridization (FISH) and next generation sequencing (NGS). The case described here showed a very unusual, but highly significant FISH signal pattern with an NTRK3 break apart probe, indicative of a functional NTRK3 rearrangement.

CASE PRESENTATION

We describe here the case of a male patient who was originally diagnosed with an adenocarcinoma of the parotid gland without evidence of metastases. After the development of multiple lung metastases, an extensive immunohistochemical and molecular examination of archived tumour tissue including analysis of NTRK was performed. NTRK expression was detected by immunohistochemistry (IHC) and then comprehensively analysed further by FISH, quantitative reverse transcription PCR (RT-qPCR), and NGS. NTRK3 break apart FISH showed multiple and very faint single 3' signals in addition to fusion signals. Quantitative reverse transcription PCR and NGS confirmed an ETV6:exon5-NTRK3:exon15 fusion. Diagnosis was therefore revised to metastatic secretory carcinoma of the salivary gland, and the patient subsequently treated with Larotrectinib, resulting in persisting partial remission.

CONCLUSIONS

Our findings underline the importance to be aware of non-canonical signal patterns during FISH analysis for detection of NTRK rearrangements. Very faint single 3' signals can indicate a functional NTRK rearrangement and therefore be of high predictive value.

The Tumor-Agnostic Treatment For Patients with Solid Tumors: a Position Paper on behalf of the AIOM- SIAPEC/IAP-SIBIOC-SIF Italian Scientific Societies

The personalized medicine is in a rapidly evolving scenario. The identification of actionable mutations is revolutionizing the therapeutic landscape of tumors. The morphological and histological tumor features are enriched by the extensive genomic profiling, and the first tumor-agnostic drugs have been approved regardless of tumor histology, guided by predictive and druggable genetic alterations. This new paradigm of "mutational oncology", presents a great potential to change the oncologic therapeutic scenario, but also some critical aspects need to be underlined. A process governance is mandatory to ensure the genomic testing accuracy and homogeneity, the economic sustainability, and the regulatory issues, ultimately granting the possibility of translating this model in the "real world". In this position paper, based on experts' opinion, the AIOM-SIAPEC-IAP-SIBIOC-SIF Italian Scientific Societies revised the new agnostic biomarkers, the diagnostic technologies available, the current availability of agnostic drugs and their present indication.

Multidisciplinary consensus on optimising the detection of NTRK gene alterations in tumours

The recent identification of rearrangements of neurotrophic tyrosine receptor kinase (NTRK) genes and the development of specific fusion protein inhibitors, such as larotrectinib and entrectinib, have revolutionised the diagnostic and clinical management of patients presenting with tumours with these alterations. Tumours that harbour NTRK fusions are found in both adults and children; and they are either rare tumours with common NTRK fusions that may be diagnostic, or more prevalent tumours with rare NTRK fusions. To assess currently available evidence on this matter, three key Spanish medical societies (the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Pathological Anatomy (SEAP), and the Spanish Society of Paediatric Haematology and Oncology (SEHOP) have brought together a group of experts to develop a consensus document that includes guidelines on the diagnostic, clinical, and therapeutic aspects of NTRK-fusion tumours. This document also discusses the challenges related to the routine detection of these genetic alterations in a mostly public Health Care System.

Impact of Endoscopic Ultrasound-Guided Tissue Acquisition on Decision-Making in Precision Medicine for Pancreatic Cancer: Beyond Diagnosis

Precision medicine in cancer treatment refers to targeted therapy based on the evaluation of biomarkers. Although precision medicine for pancreatic cancer (PC) remains challenging, novel biomarker-based therapies, such as pembrolizumab, olaparib, and entrectinib, have been emerging. Most commonly, endoscopic ultrasound-guided tissue acquisition (EUS-TA) had been used for the diagnosis of PC until now. However, advances in EUS-TA devices and biomarker testing, especially next-generation sequencing, have opened up the possibility of sequencing of various genes even in limited amounts of tissue samples obtained by EUS-TA, and identifying potential genetic alterations as therapeutic targets. Precision medicine benefits only a small population of patients with PC, but biomarker-based therapy has shown promising results in patients who once had no treatment options. Now, the role of EUS-TA has extended beyond diagnosis into decision-making regarding the treatment of PC. In this review, we mainly discuss tissue sampling by EUS-TA for biomarker testing and the current status of precision medicine for PC.

High-grade Transformation/Dedifferentiation in Salivary Gland Carcinomas: Occurrence Across Subtypes and Clinical Significance

High-grade transformation (HGT) or dedifferentiation has been described in a variety of salivary gland carcinomas, including acinic cell carcinoma, secretory carcinoma, adenoid cystic carcinoma, epithelial-myoepithelial carcinoma, polymorphous adenocarcinoma, low-grade mucoepidermoid carcinoma, and hyalinizing clear cell carcinoma. High-grade (HG) transformed tumors are composed of a conventional low-grade component characterized by specific microscopic and immunohistochemical features for the given entity, intermingled with or juxtaposed to areas of HG morphology. This is usually either poorly differentiated adenocarcinoma, carcinoma not otherwise specified, or undifferentiated carcinoma, in which the original line of differentiation is lost. The HG component is composed of solid nests of anaplastic cells with large vesicular pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. Frequent mitoses and extensive necrosis may be present. The Ki-67 labeling index is consistently higher in the HG component. The molecular genetic mechanisms responsible for HGT of salivary gland carcinomas are largely unknown, though p53 inactivation and human epidermal growth factor receptor 2 overexpression and/or gene amplification have been demonstrated in the HG component in a few examples, the frequency varies for each histologic type. Salivary gland carcinomas with HGT are more aggressive than conventional carcinomas, with a higher local recurrence rate and a poorer prognosis. They have a high propensity for cervical lymph node metastasis suggesting a need for a wider resection and neck dissection. HGT of salivary gland carcinoma can occur either at initial presentation or less commonly at the time of recurrence, sometimes following postoperative radiotherapy. The potential for HGT in almost any type of salivary gland carcinoma warrants a thorough sampling of all salivary gland malignancies to prevent oversight of a HG component.

MLH1/PMS2 Expression Could Tell Classical NTRK Fusion in Fluorescence In Situ Hybridization Positive Colorectal Carcinomas

To gain insight into the clinicopathologic profile of colorectal carcinomas harboring oncogenic NTRK fusions based on eastern populations as well as make the best testing algorithm for the screen, we use pan-Trk immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) respectively to screen NTRK fusions in a large, unselected cohort of 819 colon cancers; either IHC or FISH positive cases were further detected by next-generation sequencing (NGS). IHC staining was observed in ten (1.22%) cases. FISH positive was observed in 13 (1.59%) cases, and finally, a total of 18 cases were under both a DNA-based and an RNA-based NGS assay. RNA-based NGS was positive in 13 of 18 cases, whereas DNA-based NGS was only positive in three of 18 cases. In total 13 RNA-based NGS NTRK fusion-positive cases, only six cases were pan-TRK IHC positive versus 12 were FISH positive. More important, in 13 RNA-based NGS cases only five cases contain the full length of NTRK tyrosine kinase (TK) domain and form the classical fusion chimeras, other six cases only maintain parts of the TK domain and form the sub-classical fusion chimeras, two cases totally miss the TK domain and form the non-classical fusions. For clinicopathologic characteristics, besides the MMR (mismatch repair) status (p = 0.001), there is no difference between the NTRK fusion-positive and negative cases. Nevertheless, classical fusion cases prefer low differentiation (p = 0.001) and different patterns of growth (p < 0.001). Besides, we found all five classical NTRK fusion cases, and only one sub-classical case was harboring MLH1/PMS2 deficiency. When combining FISH and MMR (Mismatch Repair) status, besides one sub-classical case, all five classical fusions were detected, which means MLH1/PMS2 expression could further narrow the classical fusions in FISH NTRK fusion positive cases. Given the low sensitivity and specificity of the pan-Trk antibody, it would be useless to use IHC to screen NTRK fusion-positive CRCs. Combining FISH and MLH1/PMS2 IHC would be a good testing algorithm for the screen effective NTRK fusions. Finally, if patients are going to undergo TRK-based targeted therapy, only RNA-based NGS for detection of the specific fusion could tell the precise rearrangement information.

[How to test for NTRK gene fusions: A practical approach for pathologists]

The recent availability of targeted anti-TRK therapies represents a new opportunity to treat patients with advanced cancers harboring NTRK gene fusions. In this article, we present an update on the practical modalities of implementing a "NTRK testing" to search for these fusions in view of the performances and availability of the different testing methods and the epidemiological characteristics of the tumors liable to present the NTRK1, NTRK2 or NTRK3 gene fusions.

Secretory Carcinoma of the Oral Cavity: A Retrospective Case Series with Review of Literature

Secretory carcinoma (SC) is an uncommon salivary gland neoplasm of the oral cavity that microscopically may mimic acinic cell carcinoma (ACC) and mucoepidermoid carcinoma (MEC). This study describes a series of SC in minor glands with a literature review. We performed a retrospective search for oral SC, within the archives of the University of Florida, Oral Pathology and Surgical Pathology Biopsy services from 2010 to 2018. A total of 10 SCs were identified in the oral and maxillofacial region, four of which were in the minor salivary glands. The demographic, clinical, histological, and molecular findings were aggregated for all 4 cases. Patient age varied from 30 to 60 years, with an average of 45 years. Two cases each were in female and male patients. Two cases presented on the labial mucosa, and one each on the hard and soft palate. Immunohistochemical (IHC) staining showed mammaglobin positivity in all cases, GATA3 positivity in two cases, S100 positivity in three cases, and SOX10 positivity in only one case. Fluorescence in situ hybridization demonstrated positivity for ETV6-NTRK3 fusion in 4 cases. Although oral SC is rare, pathologists should be aware of the histologic overlap between the SC and other salivary gland neoplasms such as ACC and MEC. A judicious application of IHC staining would aid in diagnosis. SC should be considered in the differential diagnosis for intraoral salivary gland tumors.

Genomic Analysis of Salivary Gland Cancer and Treatment of Salivary Gland Cancers

Salivary gland cancer is a heterogenous group of tumors that presents challenges with both diagnosis and therapy. Recent advances in the classification of salivary gland cancers have led to distinct histologic and genomic criteria that successfully differentiate between cancers with similar clinical behavior and appearance. Genomic abnormalities have led to the emergence of targeted therapies being used in their therapy with drastic improvements in outcomes as well as reductions in treatment-related toxicity. Dramatic results seen with molecular targets, such as HER2, TRK, and others, indicate that this approach has the potential to yield even better treatments for the future.

Molecular Pathology of Salivary Gland Neoplasms: Diagnostic, Prognostic, and Predictive Perspective

Salivary gland neoplasms are an uncommon and widely heterogeneous group of tumors. In recent years, there has been considerable progress in efforts to reveal the molecular landscape of these tumors, although it is still limited and appears to be only the tip of the iceberg. Genomic aberrations, especially specific chromosomal rearrangements including CRTC1-MAML2 and CRTC3-MAML2 in mucoepidermoid carcinoma, MYB-NFIB and MYBL1-NFIB fusions in adenoid cystic carcinoma, PLAG1 and HMGA2 alterations in pleomorphic adenoma and carcinoma ex pleomorphic adenoma, ETV6-NTRK3 and ETV6-RET in secretory carcinoma, EWSR1-ATF1 and EWSR1-CREM in clear cell carcinoma, provide new insights into the molecular pathogenesis of various salivary gland neoplasms and help to better classify them. These genetic aberrations primarily serve as diagnostic tools in salivary gland tumor diagnosis; however, some also have promise as prognostic or predictive biomarkers. This review summarizes the latest developments in molecular pathology of salivary gland tumors with a focus on distinctive molecular characteristics.

Secretory carcinoma of salivary glands at the National Cancer Institute: A 20-year retrospective clinical, pathological, immunohistochemical and molecular study

OBJECTIVES

This study aim was to review cases of acinic cell carcinoma (the main differential diagnosis of secretory carcinoma) that were diagnosed and treated at the National Cancer Institute of Brazil (INCA) between 1996 and 2016. The primary objective was to identify underdiagnosed cases of secretory carcinoma via a clinical, immunopathological and molecular reassessment.

MATERIALS AND METHODS

This is a cross sectional study, with retrospective data collection from medical records and histological specimen review, with staining for periodic acid-Schiff (PAS) and PAS with diastase, immunohistochemistry for S-100, mammaglobin, and DOG-1, and droplet digital RT-PCR for ETV6-NTRK3. The Research Ethics Committee approved this study, and the patients allowed their participation through informed consent.

RESULTS

Eighty-three cases of acinic cell carcinoma were diagnosed and treated in the specified period at INCA, of which, seven had their diagnosis changed to secretory carcinoma.

CONCLUSION

The present study adds seven cases of secretory carcinoma to the literature, contributing to a better understanding of the epidemiological, histological, immunohistochemical and molecular characteristics of this recently described tumor. Also, the use of a comprehensive diagnostic approach, including immunohistochemical and molecular methods, along with classical morphological studies, allowed the reclassification of acinic cell carcinoma to secretory carcinoma.

Development of small-molecule tropomyosin receptor kinase (TRK) inhibitors for NTRK fusion cancers

Tropomyosin receptor kinase A, B and C (TRKA, TRKB and TRKC), which are well-known members of the cell surface receptor tyrosine kinase (RTK) family, are encoded by the neurotrophic receptor tyrosine kinase 1, 2 and 3 (NTRK1, NTRK2 and NTRK3) genes, respectively. TRKs can regulate cell proliferation, differentiation and even apoptosis through the RAS/MAPKs, PI3K/AKT and PLCγ pathways. Gene fusions involving NTRK act as oncogenic drivers of a broad diversity of adult and pediatric tumors, and TRKs have become promising antitumor targets. Therefore, achieving a comprehensive understanding of TRKs and relevant TRK inhibitors should be urgently pursued for the further development of novel TRK inhibitors for potential clinical applications. This review focuses on summarizing the biological functions of TRKs and NTRK fusion proteins, the development of small-molecule TRK inhibitors with different chemotypes and their activity and selectivity, and the potential therapeutic applications of these inhibitors for future cancer drug discovery efforts.