Gene fusion involving the insulin‐like growth factor 1 receptor in an ALK ‐negative inflammatory myofibroblastic tumour

Extracellular Interactors of the IGF System: Impact on Cancer Hallmarks and Therapeutic Approaches

Dysregulation of the insulin-like growth factor (IGF) system determines the onset of various pathological conditions, including cancer. Accordingly, therapeutic strategies have been developed to block this system in tumor cells, but the results of clinical trials have been disappointing. After decades of research in the field, it is safe to say that one of the major reasons underlying the poor efficacy of anti-IGF-targeting agents is derived from an underestimation of the molecular complexity of this axis. Genetic, transcriptional, post-transcriptional and functional interactors interfere with the activity of canonical components of this axis, supporting the need for combinatorial approaches to effectively block this system. In addition, cancer cells interface with a multiplicity of factors from the extracellular compartment, which strongly affect cell destiny. In this review, we will cover novel extracellular mechanisms contributing to IGF system dysregulation and the implications of such dangerous liaisons for cancer hallmarks and responses to known and new anti-IGF drugs. A deeper understanding of both the intracellular and extracellular microenvironments might provide new impetus to better decipher the complexity of the IGF axis in cancer and provide new clues for designing novel therapeutic approaches.

Abdominal inflammatory myofibroblastic tumour: Clinicopathological and molecular analysis of 20 cases, highlighting potential therapeutic targets

AIMS

Inflammatory myofibroblastic tumour (IMT) is a rare mesenchymal neoplasm of intermediate malignant potential, occurring at any age and at multiple sites. Epithelioid inflammatory myofibroblastic sarcoma (EIMS) is an aggressive subtype of IMT, typically involving the abdomen. Most IMTs harbour kinase gene fusions, especially involving ALK and ROS1, but 20-30% of IMTs show no detectable translocations. The aim of this study is to further delineate clinicopathological and molecular characteristics of abdominal IMT and discover potential new therapeutic targets.

METHODS AND RESULTS

In 20 IMTs, including four EIMS, RNA fusion analysis was performed, followed by multiplex DNA analysis if no ALK or ROS1 fusion was detected. Fourteen IMTs (70.0%) had an ALK translocation and the fusion partner was identified in 11, including a RRBP1::ALK fusion, not previously described in classical (non-EIMS) IMT. RANBP2::ALK fusion was demonstrated in all EIMS. One IMT had a ROS1 fusion. In all ALK/ROS1 translocation-negative IMTs mutations or fusions - as yet unreported in primary IMT - were found in genes related to the receptor tyrosine kinase (RTK)/PI3K/AKT pathway. Three of four patients with EIMS died of disease [mean survival 8 months (4-15 months)], whereas only one of 14 classical IMT patients succumbed to disease [mean follow-up time 52 months (2-204 months); P < 0.01].

CONCLUSION

This study shows the wide clinical spectrum of abdominal IMTs and affirms the poor prognosis of EIMS, raising discussion about its status as IMT subtype. Furthermore, the newly detected alterations of the RTK/PI3K/AKT pathway expand the molecular landscape of IMTs and provide potential therapeutic targets.

Corticodependent and recurrent inflammatory pseudo tumor. Analysis of cases and review

Inflammatory pseudo tumor (IP) is an infrequent process with benign evolution in most cases whose etiology and pathogenesis are unknown. It usually affects young men and children, in whom the macroscopic lesion can mimic a malignant process, which is ruled out after biopsy. Therefore, the diagnosis of certainty is histological and treatment consists of corticosteroids, leaving resection for cases in which biopsy is not possible or in which it produces local complications. We present a case of an inflammatory pseudo tumor with special corticodependence that began as a long-term periodic fever and splenic focal lesion that required splenectomy for its diagnosis and that, after decreasing the corticosteroid regimen, presented recurrences at the cerebellar and systemic level requiring the association of various immunosuppressants and rituximab to achieve remission. As a result of this case, we have performed an analysis of all the pseudo tumors diagnosed in adults in the hospitals of the province of Malaga, and it has been compared with that described in the bibliography.

Inflammatory myofibroblastic tumor of the submandibular gland Harboring MSN-ALK gene fusion: A case report and literature review

Inflammatory myofibroblastic tumors (IMTs) are rare lesions with distinct clinical, pathological, and molecular characteristics. IMTs typically arise in the abdominal soft tissues, including the mesentery, omentum, and retroperitoneum, followed by the lungs and mediastinum, and usually affect both children and young adults. Herein, we present a rare case of an IMT in the submandibular gland of a 47-year-old male patient. Microscopically, the tumor displayed an infiltrative growth pattern with diffuse glandular tissue destruction. Their backgrounds revealed characteristic spindles and inflammatory cells. Immunohistochemistry revealed positivity for anaplastic lymphoma kinase (ALK), smooth muscle actin, and calponin in neoplastic cells. The inflammatory cells and some neoplastic cells were positive for CD68. In contrast, negative staining for cytokeratin, desmin, and CD30 was observed. Furthermore, fluorescence in situ hybridization revealed ALK gene rearrangements, and next-generation sequencing detected a moesin (MSN)-ALK gene fusion. This case highlights a rare and unique occurrence of IMT originating from the submandibular gland, which exhibited an MSN-ALK gene fusion.

Inflammatory Myofibroblastic Tumor of the Placenta With Subsequent Successful Pregnancy and Benign Hysterectomy: A Case Report With 59-Month Follow-up

Inflammatory myofibroblastic tumors (IMT) are rare neoplasms of intermediate malignant potential which have been described in the gynecologic tract, predominantly in the myometrial wall, but also in association with the placenta. Like those in other organs, IMT of the placenta are characterized by molecular abnormalities, most commonly anaplastic lymphoma kinase gene rearrangements, and are often positive for anaplastic lymphoma kinase immunohistochemically. Although the clinical behavior of placental IMTs has so far proven benign, a successful intrauterine pregnancy with subsequent negative hysterectomy following a placental IMT has not been documented. Herein is presented a case of a 27-yr-old noted to have a 2 cm IMT of the extraplacental membranes at delivery, after which the patient received no further treatment. After 56 mo, the patient experienced a subsequent normal delivery in a pregnancy complicated by gestational diabetes. No longer desiring fertility, the patient elected to have a hysterectomy to confirm the absence of IMT at 59 mo and the uterus was unremarkable. This case provides insight into possible outcomes for patients with a rare tumor who may desire future fertility and may otherwise be advised to undergo hysterectomy in the setting of an unclear clinical course.

TIMP3::ALK fusions characterize a distinctive myxoid fibroblastic tumor of the vocal cords: a report of 7 cases

We report 7 cases of an indolent, variably myxoid tumor of the vocal cords, characterized by overt cellular atypia with large cells containing intranuclear and intracytoplasmic vacuoles, delicate curvilinear vessels, and sparse inflammatory infiltrate. Six patients were male, aged 15 to 65 years, and 1 patient was a 54-year-old female. All tumors were located in the superficial portion of the vocal cord. One patient suffered a recurrence that was completely resected; all patients with available follow-up data currently have no evidence of disease. The tumors contained alternating areas with myxoid stroma and more compacted regions with tumor cells organized in short fascicles, interwoven with delicate curvilinear vasculature. Overt cellular atypia with large cells containing intranuclear and intracytoplasmic vacuoles or resembling ganglion cells was present in all cases but mitoses and necrosis were absent. ALK immunostaining was positive in all cases, while most tumors were negative for smooth muscle actin. Targeted RNA-sequencing revealed an identical TIMP3::ALK fusion with exon 1 of TIMP3 gene being fused with exon 12 of ALK gene in all analyzable cases. For various reasons discussed, it remains unclear whether this tumor represents a mere subtype of IMT or a separate entity. Nevertheless, it is a morphologically distinct and diagnostically challenging lesion that needs to be recognized by surgical pathologists in order to prevent overdiagnosis in this clinically very delicate area.

Clinicopathologic and Genomic Characterization of Inflammatory Myofibroblastic Tumors of the Head and Neck: Highlighting a Novel Fusion and Potential Diagnostic Pitfall

Inflammatory myofibroblastic tumor (IMT) is a distinctive fibroblastic and myofibroblastic spindle cell neoplasm with an accompanying inflammatory cell infiltrate and frequent receptor tyrosine kinase activation at the molecular level. The tumor may recur and rarely metastasizes. IMT is rare in the head and neck region, and limited information is available about its clinicopathologic and molecular characteristics in these subsites. Therefore, we analyzed a cohort of head and neck IMTs through a multi-institutional approach. Fourteen cases were included in the provisional cohort, but 1 was excluded after molecular analysis prompted reclassification. Patients in the final cohort included 7 males and 6 females, with a mean age of 26.5 years. Tumors were located in the larynx (n=7), oral cavity (n=3), pharynx (n=2), and mastoid (n=1). Histologically, all tumors showed neoplastic spindle cells in storiform to fascicular patterns with associated chronic inflammation, but the morphologic spectrum was wide, as is characteristic of IMT in other sites. An underlying fusion gene event was identified in 92% (n=11/12) of cases and an additional case was ALK-positive by IHC but could not be evaluated molecularly. ALK represented the driver in all but 1 case. Rearrangement of ALK, fused with the TIMP3 gene (n=6) was most commonly detected, followed by 1 case each of the following fusion gene partnerships: TPM3-ALK, KIF5B-ALK, CARS-ALK, THBS1-ALK, and a novel alteration, SLC12A2-ROS1. The excluded case was reclassified as spindle cell rhabdomyosarcoma after detection of a FUS-TFCP2 rearrangement and retrospective immunohistochemical confirmation of rhabdomyoblastic differentiation, illustrating an important diagnostic pitfall. Two IMT patients received targeted therapy with crizotinib, with a demonstrated radiographic response. One tumor recurred but none metastasized. These results add to the growing body of evidence that kinase fusions can be identified in the majority of IMTs and that molecular analysis can lead to increased diagnostic accuracy and broadened therapeutic options for patients.

Unraveling the IGF System Interactome in Sarcomas Exploits Novel Therapeutic Options

Aberrant bioactivity of the insulin-like growth factor (IGF) system results in the development and progression of several pathologic conditions including cancer. Preclinical studies have shown promising anti-cancer therapeutic potentials for anti-IGF targeted therapies. However, a clear but limited clinical benefit was observed only in a minority of patients with sarcomas. The molecular complexity of the IGF system, which comprises multiple regulators and interactions with other cancer-related pathways, poses a major limitation in the use of anti-IGF agents and supports the need of combinatorial therapeutic strategies to better tackle this axis. In this review, we will initially highlight multiple mechanisms underlying IGF dysregulation in cancer and then focus on the impact of the IGF system and its complexity in sarcoma development and progression as well as response to anti-IGF therapies. We will also discuss the role of Ephrin receptors, Hippo pathway, BET proteins and CXCR4 signaling, as mediators of sarcoma malignancy and relevant interactors with the IGF system in tumor cells. A deeper understanding of these molecular interactions might provide the rationale for novel and more effective therapeutic combinations to treat sarcomas.

Inflammatory myofibroblastic tumor: molecular landscape, targeted therapeutics, and remaining challenges

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumor of intermediate malignant potential that predominantly affects children, adolescents and young adults. IMT has a predilection for the lung, abdomen, pelvis, and retroperitoneum, however, can affect any part of the body. IMT is typically localized, and multifocal or metastatic disease is uncommon. Complete surgical resection is the treatment of choice when feasible. There is no established standard of care for unresectable and advanced IMT. Approximately half of IMTs harbor anaplastic lymphoma kinase (ALK) gene rearrangements, and fusions involving ROS1, PDGFRβ, RET and NTRK have also been described. Given the molecular landscape of IMT, management of these tumors has evolved to include tyrosine kinase inhibitors and novel targeted therapeutics. This review highlights the molecular characteristics, evolution of targeted therapies and the remaining challenges in the management of IMT.

Calcified chondroid mesenchymal neoplasms with FN1-receptor tyrosine kinase gene fusions including FGFR2, FGFR1, MERTK, NTRK1, and TEK: a molecular and clinicopathologic analysis

Translocations involving FN1 have been described in a variety of neoplasms that share the presence of a cartilage matrix and may also contain a variable extent of calcification. Fusions of FN1 to FGFR1 or FGFR2 have been reported in nine soft tissue chondromas, mostly demonstrated indirectly by FISH analysis. Delineation of FN1 fusions with various partner genes will facilitate our understanding of the pathogenesis and diagnostic classification of these neoplasms. In this study, we present molecular, clinical, and pathologic features of 12 cartilaginous soft tissue neoplasms showing a predilection for the TMJ region and the distal extremities. We analyzed for gene fusions with precise breakpoints using targeted RNA-seq with a 115-gene panel. We detected gene fusions in ten cases, including three novel fusions, FN1-MERTK, FN1-NTRK1, and FN1-TEK, each in one case, recurrent FN1-FGFR2 fusion in five cases, FN1-FGFR1 in one case, and FGFR1-PLAG1 in one case. The breakpoints in the 5' partner gene FN1 ranged from exons 11-48, retaining the domains of a signal peptide, FN1, FN2, and/or FN3, while the 3' partner genes retained the transmembrane domain, tyrosine kinase (TK) domains, and/or Ig domain. The tumors are generally characterized by nodular/lobular growth of polygonal to stellate cells within a chondroid matrix, often accompanied by various patterns of calcification, resembling those described for the chondroblastoma-like variant of soft tissue chondroma. Additional histologic findings include extensive calcium pyrophosphate dihydrate deposition in two cases and features resembling tenosynovial giant cell tumor (TGCT). Overall, while the tumors from our series show significant morphologic overlap with chondroblastoma-like soft tissue chondroma, we describe findings that expand the morphologic spectrum of these neoplasms and therefore refer to them as "calcified chondroid mesenchymal neoplasms." These neoplasms represent a spectrum of chondroid/cartilage matrix-forming tumors harboring FN1-receptor TK fusions that include those classified as soft tissue chondroma as well as chondroid TGCT.

Outstanding Response in a Patient With ROS1-Rearranged Inflammatory Myofibroblastic Tumor of Soft Tissues Treated With Crizotinib: Case Report

Inflammatory myofibroblastic tumor (IMT) is a very rare subtype of sarcoma, which frequently harbor chromosomal rearrangements, including anaplastic lymphoma kinase (ALK) rearrangements (almost 50% of the IMTs) and other kinase fusions such as ROS1. ROS1 fusions are present in about 10% of IMT, almost half of the ALK-negative IMT patients. Apart from radical surgery for resectable tumors, there is no standard-of-care therapy for advanced IMTs. Nonetheless, the use of tyrosine kinase inhibitors has shown promising efficacy in IMT patients with targetable genomic alterations. We report the case of a 24-year-old patient with chemotherapy-refractory metastatic IMT harboring ROS1 kinase fusion, who experienced a significant clinical and pathological response to crizotinib. This clinical case highlights the need to assess all patients with unresectable IMTs for chromosomal abnormalities and gene mutations and address them to targeted agents as well as clinical trials.

Pregnancy-associated Inflammatory Myofibroblastic Tumors of the Uterus Are Clinically Distinct and Highly Enriched for TIMP3-ALK and THBS1-ALK Fusions

As inflammatory myofibroblastic tumors (IMTs) have become more widely recognized in the female genital tract, an intriguing subset of uterine tumors associated with pregnancy has emerged. Whether uterine IMTs occurring in the setting of pregnancy are clinically or biologically distinct from other uterine IMTs is unknown. Furthermore, little is known about the perinatal factors that may influence the development of these tumors. Here, we report the largest case series of 8 pregnancy-associated IMTs. All pregnancy-associated IMTs in this series occurred in association with pregnancy complications, including abnormal implantation (n=1), gestational diabetes (n=2), preeclampsia and/or HELLP syndrome (n=2), antiphospholipid syndrome (n=1), premature rupture of membranes (n=1), and hepatitis B (n=1). Notably, all IMTs were expelled at the time of delivery or immediately postpartum and were either adherent to the placenta or presented as separate, detached tissue. Tumors ranged from 2.0 to 6.0 cm (median, 3.9 cm), were well-circumscribed and showed classic histologic features of IMTs, including myxoid stroma and a lymphoplasmacytic infiltrate. Seven of 8 cases were positive by ALK immunohistochemistry and confirmed to have an ALK gene rearrangement by fluorescent in situ hybridization and RNA sequencing. The ALK-rearranged IMTs were found to be particularly enriched for TIMP3-ALK (n=5) and THBS1-ALK (n=2) fusions. The single case that was negative for an ALK rearrangement exhibited the classic morphology of an IMT. None of the 4 cases with available clinical follow-up recurred. The clinicopathologic features of pregnancy-associated IMTs in this series in conjunction with those reported in the literature suggests that these may be transient tumors that develop during pregnancy and shed at parturition; they appear to have a relatively indolent clinical course and favorable outcome, although studies with a longer duration of follow-up are still required.

Inflammatory myofibroblastic tumor arising from soft tissues of extremities harboring a novel CLIP2-ALK fusion

A 34-year-old Chinese woman found a lump in her left leg for more than 3 weeks without any discomfort. Grossly, the tumor was relatively well delineated with focal infiltration. Histopathologic evaluation showed a compact fascicular spindle cell proliferation with variable myxoid and collagenous stroma and scattered inflammatory infiltrate. Immunohistochemically, the tumor cells showed positive expression of ALKD5F3 and SMA and negative expression of CD34, desmin, and cytokeretin. Fluorescence in situ hybridization analysis of the ALK locus showed break-apart signals in 20% of tumor cells, and DNA sequencing discovered a novel CLIP2-ALK fusion gene. The lesion was diagnosed as an inflammatory myofibroblastic tumor (IMT). To the best of our knowledge, this is the first case with CLIP2-ALK gene fusion in the somatic soft tissue IMTs.

Gene rearrangements in consecutive series of pediatric inflammatory myofibroblastic tumors

BACKGROUND

Inflammatory myofibroblastic tumors (IMTs) are exceptionally rare neoplasms, which are often driven by rearranged tyrosine kinases.

METHODS

This study considered 33 consecutive patients with IMT (median age, 6.6; age range, 0.6-15.8 years). RNA and cDNA were successfully obtained in 29 cases. The molecular analysis included sequential tests for 5'/3'-end unbalanced gene expression, variant-specific PCR, and next-generation sequencing (NGS).

RESULTS

5'/3'-end unbalanced ALK expression was revealed in 15/29 (52%) IMTs. Strikingly, all these tumors demonstrated high amount of ALK protein detected by immunohistochemistry. Variant-specific PCR was capable of identifying the type of ALK rearrangement in 11/15 IMTs with 5'/3'-end unbalanced ALK expression. The remaining four tumors were analyzed by NGS; two known and two novel (CLTC-ins6del84-ALK and EEF1G-ALK) ALK rearrangements were detected. Five IMTs demonstrated 5'/3'-end unbalanced ROS1 expression, and all these tumors carried TFG-ROS1 fusion. Nine tumors, which were negative for 5'/3'-end unbalanced ALK/ROS1 expression, were subjected to further analysis. Variant-specific PCR revealed two additional tumors with gene rearrangements (TFG-ROS1 and ETV6-NTRK3). The remaining seven IMTs were tested by NGS; single instances of TFG-ROS1 and novel SRF-PDGFRb translocations were detected.

CONCLUSIONS

Twenty-four of 29 IMTs (83%) were shown to have druggable rearrangements involving tyrosine kinases, 20 of these 24 gene fusions were detectable by simple and inexpensive PCR assay, which is based on the detection 5'/3'-end unbalanced gene expression.

IGF2/IGF1R Signaling as a Therapeutic Target in MYB-Positive Adenoid Cystic Carcinomas and Other Fusion Gene-Driven Tumors

Chromosome rearrangements resulting in pathogenetically important gene fusions are a common feature of many cancers. They are often potent oncogenic drivers and have key functions in central cellular processes and pathways and encode transcription factors, transcriptional co-regulators, growth factor receptors, tyrosine kinases, and chromatin modifiers. In addition to being useful diagnostic biomarkers, they are also targets for development of new molecularly targeted therapies. Studies in recent decades have shown that several oncogenic gene fusions interact with the insulin-like growth factor (IGF) signaling pathway. For example, the MYB-NFIB fusion in adenoid cystic carcinoma is regulated by IGF1R through an autocrine loop, and IGF1R is a downstream target of the EWSR1-WT1 and PAX3-FKHR fusions in desmoplastic small round cell tumors and alveolar rhabdomyosarcoma, respectively. Here, we will discuss the mechanisms behind the interactions between oncogenic gene fusions and the IGF signaling pathway. We will also discuss the role of therapeutic inhibition of IGF1R in fusion gene driven malignancies.

Identification of candidates for driver oncogenes in scirrhous-type gastric cancer cell lines

Scirrhous‐type gastric cancer (SGC) is one of the most intractable cancer subtypes in humans, and its therapeutic targets have been rarely identified to date. Exploration of somatic mutations in the SGC genome with the next‐generation sequencers has been hampered by markedly increased fibrous tissues. Thus, SGC cell lines may be useful resources for searching for novel oncogenes. Here we have conducted whole exome sequencing and RNA sequencing on 2 SGC cell lines, OCUM‐8 and OCUM‐9. Interestingly, most of the mutations thus identified have not been reported. In OCUM‐8 cells, a novel CD44‐IGF1R fusion gene is discovered, the protein product of which ligates the amino‐terminus of CD44 to the transmembrane and tyrosine‐kinase domains of IGF1R. Furthermore, both CD44 and IGF1R are markedly amplified in the OCUM‐8 genome and abundantly expressed. CD44‐IGF1R has a transforming ability, and the suppression of its kinase activity leads to rapid cell death of OCUM‐8. To the best of our knowledge, this is the first report describing the transforming activity of IGF1R fusion genes. However, OCUM‐9 seems to possess multiple oncogenic events in its genome. In particular, a novel BORCS5‐ETV6 fusion gene is identified in the OCUM‐9 genome. BORCS5‐ETV6 possesses oncogenic activity, and suppression of its message partially inhibits cell growth. Prevalence of these novel fusion genes among SGC awaits further investigation, but we validate the significance of cell lines as appropriate reagents for detailed genomic analyses of SGC.

Calcifying fibrous tumor and inflammatory myofibroblastic tumor are epigenetically related: A comparative genome-wide methylation study

Based on histological findings, calcifying fibrous tumor (CFT) may be a late (burned out) stage of inflammatory myofibroblastic tumor (IMT). This concept, however, has not been proven by molecular means. Five CFTs were analyzed for IMT-related rearrangements in ALK, ROS1 and RET using fluorescence in situ hybridization (FISH). Additionally, genome-wide methylation patterns were investigated and compared with IMT (n = 7), leiomyoma (n = 7), angioleiomyoma (n = 9), myopericytoma (n = 7) and reactive soft tissue lesions (n = 10) using unsupervised hierarchical cluster analysis and t distributed stochastic neighbor embedding. CFT patients, 4 females and 1 male, had a median age of 20 years ranging from 7 to 43 years. Two patients were younger than 18 years old. The tumors originated in the abdomen (n = 4) and axilla (n = 1). Histologically, all lesions were (multi) nodular and hypocellular consisting of bland looking (myo)fibroblasts embedded in a collagenous matrix with calcifications. FISH analysis brought up negative results for ALK, RET and ROS1 rearrangements. However, genome-wide methylation analysis revealed overlapping methylation patterns of CFT and IMT forming a distinct homogeneous methylation cluster with exception of one case clustering with myopericytoma/angioleiomyoma. In conclusion, DNA methylation profiling supports the concept that CFT and IMT represent both ends of a spectrum of one entity with CFT being the burn out stage of IMT.