Therapeutic options in inoperable ROS1-rearranged inflammatory myofibroblastic tumor of the tongue in a child: a case report and literature review

Methotrexate resistance and its regulatory mechanisms in pediatric tumors and beyond

Methotrexate (MTX) is a critical antimetabolite drug in treating various pediatric diseases, including acute lymphoblastic leukemia (ALL), non-Hodgkin lymphoma (NHL), brain tumors, osteosarcoma, inflammatory myofibroblastic tumor (IMT), juvenile scleroderma (JS), and juvenile idiopathic arthritis (JIA). MTX acts as a folate antagonist by inhibiting dihydrofolate reductase (DHFR), an enzyme essential for the synthesis of tetrahydrofolate. This disruption impairs DNA synthesis, repair, and cellular replication, particularly affecting rapidly dividing cells. Despite its efficacy, MTX resistance poses significant challenges, particularly in pediatric oncology, where it undermines the ability to achieve sustained therapeutic effects, resulting in reduced therapeutic efficacy and poor prognosis. The mechanisms of MTX resistance encompassed reduced enzyme activity pivotal for MTX metabolism, enhanced expression of efflux transporters, genetic variations, and alterations in signaling pathways. Multifaceted strategies have been explored to overcome MTX resistance. Combination therapies with ginger extract, gold nanoparticles, and arsenic trioxide (ATO) have been investigated to augment MTX's cytotoxic effects. Synergies with mTOR inhibitors and MDM2 inhibitors have demonstrated enhanced outcomes in ALL. In JIA, targeting ATP-binding cassette (ABC) transporters and modulating transforming growth factor‑β (TGF-β) signaling pathways have emerged as promising approaches. For osteosarcoma, emphasis on autophagy pathways and non-coding RNAs influencing chemotherapy sensitivity could enhance MTX effectiveness. This review delineates MTX's therapeutic roles, elucidates its resistance mechanisms, and discusses current and potential strategies for managing MTX resistance to bolster treatment effectiveness in pediatric tumors and other diseases. This knowledge base could underpin further research and development of personalized treatments to optimize MTX's clinical benefits.

Chinese Expert Consensus on the Diagnosis and Treatment of Inflammatory Myofibroblastic Tumor

Inflammatory myofibroblastic tumor (IMT) is a rare spindle-cell neoplasm. IMT currently suffers from a paucity of standardized diagnostic and therapeutic guidelines. The Chinese expert consensus committee on the diagnosis and treatment of IMT formed an "Expert consensus on the diagnosis and treatment of inflammatory myofibroblastic tumor". This consensus was developed through a comprehensive synthesis of expert opinions, an extensive review of the literature, and a series of offline and online deliberations. The committee aspires that this consensus will enhance the therapeutic outcomes and prognosis for patients with IMT in the future.

Reclassification of a spindle cell sarcoma after identification of a TFG-ROS1 fusion: A case demonstrating the clinical benefit of next-generation sequencing in sarcoma

BACKGROUND

Inflammatory myofibroblastic tumors (IMTs) are rare mesenchymal soft tissue sarcomas that often present diagnostic challenges due to their wide and varied morphology. A subset of IMTs have fusions involving ALK or ROS1. The role of next-generation sequencing (NGS) for classification of unselected sarcomas remains controversial.

METHODS AND RESULTS

We report a case of a metastatic sarcoma in a 34-year-old female originally diagnosed as an unclassified spindle cell sarcoma with myofibroblastic differentiation and later reclassified as IMT after NGS revealed a TFG-ROS1 rearrangement. Histologically, the neoplasm had spindle cell morphology with a lobulated to focally infiltrative growth pattern with scant inflammatory cell infiltrate. Immunohistochemistry demonstrated focal desmin and variable smooth muscle actin staining but was negative for SOX10, S100, and CD34. Fluorescence in situ hybridization was negative for USP6 or ALK gene rearrangements. NGS revealed a TFG-ROS1 rearrangement and the patient was treated with crizotinib with clinical benefit.

CONCLUSIONS

We discuss the role of NGS as well as its potential benefit in patients with unresectable, ALK-negative metastatic disease. Considering this case and previous literature, we support the use of NGS for patients requiring systemic treatment.

Individualized targeted treatment in a case of a rare TFG::ROS1 fusion positive inflammatory myofibroblastic tumor (IMT)

BACKGROUND

Inflammatory myofibroblastic tumor (IMTs) are rare mesenchymal neoplasms with slow growth. Resection is considered as therapeutic standard, with chemotherapy being insufficiently effective in advanced disease. ALK translocations are present in 50% of cases, ROS1 fusions (YWHAE::ROS1, TFG::ROS1) are extremely rare. Here, we present a case with TFG::ROS1 fusion and highlight the significance of molecular tumor boards (MTBs) in clinical precision oncology for post-last-line therapy.

CASE PRESENTATION

A 32-year-old woman presented with IMT diagnosed at age 27 for biopsy and treatment evaluation. Previous treatments included multiple resections and systemic therapy with vinblastine, cyclophosphamide, and methotrexate. A computed tomography scan showed extensive tumor infiltration of the psoas muscles and the posterior abdomen. Next generation sequencing revealed an actionable ROS1 fusion (TFG::ROS1) with breakpoints at exon 4/35 including the kinase domain and activating the RAS-pathway. TFG, the Trk-fused gene, exerts functions such as intracellular trafficking and exhibits high sequence homology between species. Based on single reports about efficacy of ROS1-targeting in ROS1 translocation positive IMTs the patient was started on crizotinib, an ATP-competitive small molecule c-MET, ALK and ROS1-inhibitor. With a follow-up of more than 9 months, the patient continues to show a profound response with major tumor regression, improved quality of life and no evidence for severe adverse events.

CONCLUSION

This case underscores the importance of the availability of modern molecular diagnostics and interdisciplinarity in precision oncology to identify rare, disease-defining genotypes that make an otherwise difficult-to-treat disease targetable.

Inflammatory myofibroblastic tumors: recent progress and future of targeted therapy

An inflammatory myofibroblastic tumor is a rare component of bone and soft-tissue sarcomas that has distinct pathological features as a lymphoplasmacytic inflammatory infiltrate. As is the case for other non-small round cell sarcomas, surgical resection remains the standard treatment strategy for inflammatory myofibroblastic tumors, but recurrence is possible. Concerning systemic therapy, the available data for conventional chemotherapy (such as those of doxorubicin-based regimens) are limited, and case reports of anti-inflammatory inflammatory myofibroblastic tumor treatments describe some degree of symptom relief and efficacy against tumor progression. However, as more information about cancer genomics accumulates, the potential for molecularly targeted therapies for inflammatory myofibroblastic tumors has become more promising. Approximately half of inflammatory myofibroblastic tumors harbor anaplastic lymphoma kinase (ALK) fusion genes, and the other half could have potentially targetable fusion genes or mutations such as ROS1, NTRK and RET; case reports demonstrating the clinical efficacy of treatments targeted to inflammatory myofibroblastic tumor have been published, as have several prospective clinical trials. Few drugs are approved for the treatment of inflammatory myofibroblastic tumor, and most of them were approved for tumor-agnostic indications. Drugs that could be used for pediatric indications and dosing in inflammatory myofibroblastic tumor have also not been established. To provide effective targeted therapy for rare diseases such as inflammatory myofibroblastic tumor, it is necessary to obtain clinical evidence by designing and performing clinical trials and to find a path toward regulatory approval.