Case Report: An NTRK1 fusion-positive embryonal rhabdomyosarcoma: clinical presentations, pathological characteristics and genotypic analyses

Rhabdomyosarcoma (RMS) is a prevalent form of soft tissue sarcoma that primarily affects children. Pediatric RMS is characterized by two distinct histological variants: embryonal (ERMS) and alveolar (ARMS). ERMS is a malignant tumor with primitive characteristics resembling the phenotypic and biological features of embryonic skeletal muscles. With the widespread and growing application of advanced molecular biological technologies, such as next-generation sequencing (NGS), it has been possible to determine the oncogenic activation alterations of many tumors. Specifically for soft tissue sarcomas, the determination of tyrosine kinase gene and protein related changes can be used as diagnostic aids and may be used as predictive markers for targeted tyrosine kinase inhibition therapy. Our study reports a rare and exceptional case of an 11-year-old patient diagnosed with ERMS, who tested positive for MEF2D-NTRK1 fusion. The case report presents a comprehensive overview of the clinical, radiographic, histopathological, immunohistochemical, and genetic characteristics of a palpebral ERMS. Furthermore, this study sheds light on an uncommon occurrence of NTRK1 fusion-positive ERMS, which may provide theoretical basis for therapy and prognosis.

Case report: NTRK1-rearranged cervical sarcoma with fibrosarcoma like morphology presenting in a 13-year-old managed with a neo-adjuvant TRK-inhibitor and surgical excision

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NTRK fusion-positive fibrosarcoma like tumour of the cervix in a paediatric patient.

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Fertility sparing surgery achieved with the use of a neo-adjuvant TKi.

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Identifying NTRK fusions may afford conservative treatment options in these tumours.

This case report reviews the case of a 13-year-old patient who presented with a 9 cm NTRK1-rearranged cervical sarcoma with fibrosarcoma like morphology. At presentation the lesion filled her vagina and pelvis and any attempt at surgical removal would have been morbid and led to loss of fertility. These neoplasms are extremely rare with 18 cases of the uterine cervix reported in the literature, none of which have occurred in a paediatric patient, and none of whom have received neo-adjuvant therapy prior to excision. Based upon evidence that has shown good tolerability and responses of paediatric NTRK fusion-positive solid tumours to TRK inhibitors, both in the neo-adjuvant and upfront setting, this patient was managed with neo-adjuvant entrectinib. Following a dramatic reduction in tumour size confirmed by imaging, she underwent conservative fertility sparing surgery with final histopathology showing no residual disease.

Evidence of NTRK1 Fusion as Resistance Mechanism to EGFR TKI in EGFR+ NSCLC: Results From a Large-Scale Survey of NTRK1 Fusions in Chinese Patients With Lung Cancer

BACKGROUND

Neurotrophin receptor kinase (NTRK) gene fusions (NTRK+) are rare but actionable oncogenic drivers present in a wide variety of solid tumors. However, the clinicopathologic characteristics of NTRK1 fusion-positive non-small-cell lung cancer are largely unknown.

MATERIALS AND METHODS

Lung cancer tissue specimens and/or circulating cell-free DNA from patients with lung cancer who had undergone molecular profiling at a Clinical Laboratory Improvement Amendments (CLIA)-certified genomics laboratory in China were retrospectively reviewed. The laboratory performed NTRK1 fusion detection using hybridization-based targeted next-generation sequencing. The patients' clinical characteristics and treatment history were retrieved from the database for further evaluation.

RESULTS

A total of 21,155 Chinese lung cancer cases had undergone molecular profiling from April 2016 to March 2019, including 13,630 adenocarcinoma cases. Of these cases, 12 were positive for NTRK1 fusion, including 10 cases of adenocarcinoma (0.073%), 1 primary sarcomatoid carcinoma, and 1 with an unknown histologic classification. Seven fusion partners (CD74, interferon regulatory factor 2 binding protein 2 [IRF2BP2], lamin A/C [LMNA], PHD finger protein 20 [PHF20], sequestosome 1 [SQSTM1], tropomyosin 3 [TPM3], TPR) were identified. Additionally, 1 unique rearrangement occurred upstream of the transcription start site of BCL9 fused to exon 12 of NTRK1 (intragenic region, BCL9-NTRK1). Of the 12 cases of NTRK1+ lung cancer, 6 had had concurrent activating EGFR mutations and/or had received previous treatment with EGFR tyrosine kinase inhibitors (TKIs), with 2 having concurrent EGFR T790M and 1 additional EGFR C797S.

CONCLUSIONS

NTRK1+ lung cancer cases are extremely rare with multiple fusion partners. Additionally, emergence of NTRK1+ fusion might act as a resistance mechanism to EGFR TKIs. When performing comprehensive analysis of acquired resistance to EGFR TKIs, the ability to detect NTRK1 fusions will be important.

Molecular genetic characterization reveals linear tumor evolution in a pulmonary sarcomatoid carcinomas patient with a novel PHF20-NTRK1 fusion: a case report

BACKGROUND

Pulmonary sarcomatoid carcinoma (SC) consists of both carcinomatous and sarcomatous tumors with high degree of malignancy, rapid progression, and poor prognosis. However, little is known regarding how pulmonary SC develops and progresses.

CASE PRESENTATION

A 66-year-old male was initially diagnosed with stage IIIa lung cancer containing both adenocarcinoma (ADC) and SC. Adjuvant chemotherapy was administrated post-surgery, however, recurrence with SC only soon followed. Mutation profiling of the patient's microdissected ADC and SC components of the primary lesion and recurrent tumor was performed by targeted next-generation sequencing (NGS) of 416 cancer-relevant genes. Our data showed that primary SC/ADC and the recurrent SC shared multiple gene mutations including EGFR, NF1, TP53, CDKN2B, and SMARCA4, while both primary and recurrent SCs had a unique TP53 exon 4 splicing mutation frequently observed in sarcoma. Interestingly, a novel PHF20-NTRK1 fusion was acquired in the recurrent SC, which may be a potential driver for SC recurrence.

CONCLUSIONS

The molecular genetic characteristics of tumor tissues at different stages reveals a linear tumor evolution model in this case, and support that the primary SC derived from the original lung ADC during the evolution of the tumor. We also identified a novel PHF20-NTRK1 fusion, which may contribute to the disease recurrence, and that can be potentially targeted with NTRK1 inhibitors for treatment.

NTRK1 fusions for the therapeutic intervention of Korean patients with colon cancer

The identification and clinical validation of cancer driver genes are essential to accelerate the translational transition of cancer genomics, as well as to find clinically confident targets for the therapeutic intervention of cancers. Here we identified recurrent LMNA-NTRK1 and TPM3-NTRK1 fusions in Korean patients with colon cancer (3 out of 147, 2%) through next-generation RNA sequencing (RNA-seq). NTRK1 fusions were mutually exclusive oncogenic drivers of colon cancer that were accompanied with in vitro potential of colony formation and in vivo tumorigenicity comparable to KM12, a human colon cancer cell line harboring TPM3-NTRK1 fusion. NTRK1-encoded TrkA protein was prevalent in 11 out of 216 Korean (5.1%) and 28 out of 472 Chinese patients (5.9%) from independent cohorts, respectively. The expression level of TrkA was significantly correlated with NTRK1 fusion (p = 0.0192), which was verified by a fluorescence in situ hybridization (FISH). Korean patients with TrkA-positive colon cancer had a marginal but significant shorter overall survival time than TrkA-negative colon cancer [hazard ratio (HR) = 0.5346, 95% confidential interval (CI) = 0.2548-0.9722, p = 0.0411]. In addition, KM12 cell line was sensitive to selective TrkA inhibitors. These results demonstrate that NTRK1 fusion is granted as a clinically relevant target for therapeutic intervention of colon cancer.