Tyrosine kinase altered spindle cell neoplasms with EGFR internal tandem duplications

EGFR-KDD Myofibroblastic Neoplasm or Congenital Peribronchial Myofibroblastic Tumor (CPMT)? Report of a Congenital Myofibroblastic Neoplasm With Unusual Histologic Features

EGFR-kinase-domain duplication (KDD) has been reported in Infantile fibrosarcoma-like myofibroblastic tumors and cellular mesoblastic nephroma. We report a pulmonary neoplasm with EGFR-(KDD) and infantile fibrosarcoma-like histologic features in a female infant with an unusual clinical and histologic evolution, characterized by persistent disease with morphologic features of Congenital Peribronchial Myofibroblastic Tumor (CPMT) after chemotherapy and targeted therapy. The CPMT morphology with EGFR-KDD in the post-therapy specimen might be an evolution induced by the treatment, which suggests the hypothesis that CPMT is part of the morphologic spectrum of infantile fibrosarcoma/cellular mesoblastic nephroma.

Congenital Peribronchial Myofibroblastic Tumors Harbor a Recurrent EGFR Kinase Domain Duplication

Congenital peribronchial myofibroblastic tumor (CPMT) is a rare benign infantile pulmonary neoplasm that presents prenatally, or early in infancy, and exhibits distinctive histologic features characterized by the presence of cartilaginous islands intermixed with bland spindle cells, not uncommonly displaying prominent mitoses. Despite its benign nature, CPMT can lead to fetal demise, postnatal respiratory distress, or complications from perinatal surgical resection. Although the morphologic and clinical features of CPMT are well described, its molecular features and oncogenesis remain elusive. Following the detection of EGFR kinase domain duplication (KDD) of exons 18 to 25 in an index case, we identified 3 additional cases of morphologically classic and clinically well-characterized CPMTs from the archives and performed targeted RNA- and DNA-based profiling via next-generation sequencing for detection of rearrangements, sequence variants, and copy number variants on all cases. Two cases were detected prenatally, 1 patient presented at birth, and 1 at 8 weeks of life. All tumors were resected, with a follow-up period ranging from 0 days to 10 years. One patient died shortly after surgical resection, and the other 3 had no recurrences. In all cases, EGFR KDD was detected. In 2 out of 4 cases, gains of select whole chromosomes were noted. Our findings establish EGFR KDD as a recurrent oncogenic driver of CPMT. Notably, this alteration is also found in classical congenital mesoblastic nephromas, infantile kidney tumors with which CPMTs share striking morphologic and clinical similarities. This strongly suggests that CPMTs and classical congenital mesoblastic nephromas share common oncogenesis, and represent the same tumor in different locations. EGFR KDDs have also been reported in neonatal soft tissue tumors with infantile fibrosarcoma-like histology and cartilaginous differentiation, raising questions about their relationship. EGFR KDD emerges as a diagnostic marker, a potential therapeutic target, and a window into the oncogenesis of a distinct subset of infantile mesenchymal tumors.

Pediatric Fibromatosis Lacks the Internal Tandem Duplication of EGFR Seen in Congenital Mesoblastic Nephroma

Classical and mixed congenital mesoblastic nephroma (CMN) are characterized by an internal tandem duplication (ITD) of the EGFR gene, in contrast to cellular CMN that usually harbors an ETV6::NTRK3 gene fusion. This same fusion occurs in infantile fibrosarcoma, and this tumor can be considered as the soft tissue equivalent of cellular CMN. A soft tissue equivalent of classic/mixed CMN remains undefined at the genetic level. Since classical CMN resembles fibromatosis of soft tissue histologically, we asked whether fibromatosis in children might show EGFR ITD. ITD was investigated using the polymerase chain reaction and primers for exons 18 and 25 of the EGFR gene. Seven of the eight cases of classical or mixed CMN were positive by this approach, but none of the five cellular CMNs. Of 11 cases of fibromatosis (six plantar, two digital, and three desmoid), none were positive for EGFR ITD. Within the limits of this small study, we conclude that pediatric fibromatosis is likely not characterized by EGFR ITD. There are isolated reports of pediatric soft tissue tumors that harbor EGFR ITD, but these have the appearance of infantile fibrosarcoma or mixed CMN rather than fibromatosis. We did not find any such cases, since all 14 cases of infantile fibrosarcoma in our study had an ETV6::NTRK3 fusion. The soft tissue tumors with EGFR ITD are not a morphologic match for the low-grade histology of classical CMN. Whether they have a similar favorable biology or behave more like fibrosarcoma with an ETV6::NTRK3 fusion or an alternative fusion involving other kinases remains to be determined.

The emerging role of noncoding RNAs in the EGFR signaling pathway in lung cancer

Noncoding ribonucleic acids (ncRNAs) have surfaced as essential orchestrators within the intricate system of neoplastic biology. Specifically, the epidermal growth factor receptor (EGFR) signalling cascade shows a central role in the etiological underpinnings of pulmonary carcinoma. Pulmonary malignancy persists as a preeminent contributor to worldwide mortality attributable to malignant neoplasms, with non-small cell lung carcinoma (NSCLC) emerging as the most predominant histopathological subcategory. EGFR is a key driver of NSCLC, and its dysregulation is frequently associated with tumorigenesis, metastasis, and resistance to therapy. Over the past decade, researchers have unveiled a complex network of ncRNAs, encompassing microRNAs, long noncoding RNAs, and circular RNAs, which intricately regulate EGFR signalling. MicroRNAs, as versatile post-transcriptional regulators, have been shown to target various components of the EGFR pathway, influencing cancer cell proliferation, migration, and apoptosis. Additionally, ncRNAs have emerged as critical modulators of EGFR signalling, with their potential to act as scaffolds, decoys, or guides for EGFR-related proteins. Circular RNAs, a relatively recent addition to the ncRNA family, have also been implicated in EGFR signalling regulation. The clinical implications of ncRNAs in EGFR-driven lung cancer are substantial. These molecules exhibit diagnostic potential as robust biomarkers for early cancer detection and personalized treatment. Furthermore, their predictive value extends to predicting disease progression and therapeutic outcomes. Targeting ncRNAs in the EGFR pathway represents a novel therapeutic approach with promising results in preclinical and early clinical studies. This review explores the increasing evidence supporting the significant role of ncRNAs in modulating EGFR signalling in lung cancer, shedding light on their potential diagnostic, prognostic, and therapeutic implications.

Expanding the Clinical Utility of Targeted RNA Sequencing Panels beyond Gene Fusions to Complex, Intragenic Structural Rearrangements

Gene fusions are a form of structural rearrangement well established as driver events in pediatric and adult cancers. The identification of such events holds clinical significance in the refinement, prognostication, and provision of treatment in cancer. Structural rearrangements also extend beyond fusions to include intragenic rearrangements, such as internal tandem duplications (ITDs) or exon-level deletions. These intragenic events have been increasingly implicated as cancer-promoting events. However, the detection of intragenic rearrangements may be challenging to resolve bioinformatically with short-read sequencing technologies and therefore may not be routinely assessed in panel-based testing. Within an academic clinical laboratory, over three years, a total of 608 disease-involved samples (522 hematologic malignancy, 86 solid tumors) underwent clinical testing using Anchored Multiplex PCR (AMP)-based RNA sequencing. Hematologic malignancies were evaluated using a custom Pan-Heme 154 gene panel, while solid tumors were assessed using a custom Pan-Solid 115 gene panel. Gene fusions, ITDs, and intragenic deletions were assessed for diagnostic, prognostic, or therapeutic significance. When considering gene fusions alone, we report an overall diagnostic yield of 36% (37% hematologic malignancy, 41% solid tumors). When including intragenic structural rearrangements, the overall diagnostic yield increased to 48% (48% hematologic malignancy, 45% solid tumor). We demonstrate the clinical utility of reporting structural rearrangements, including gene fusions and intragenic structural rearrangements, using an AMP-based RNA sequencing panel.