Tropomyosin receptor kinases in sarcomas - of joy and despair.

PURPOSE OF REVIEW: The relatively recent discovery of neurotrophic tropomyosin receptor kinase (NTRK) gene arrangements as pan-tumor predictive biomarkers has led to impressive novel treatments for patients with TRK fusions. Although the number of patients who qualify for treatment is vanishingly small for cancer patients in general, a few histological subsets of sarcomas exhibit NTRK fusions more commonly leading to large expectations within the sarcoma community. RECENT FINDINGS: Larotrectenib and entrectenib have recently been approved based on durable responses in TRK positive cancers with nonresectable or metastatic disease, including many sarcomas. Identification of resistance mutations to TRKi has led to the development of novel salvage therapies which may soon further expand the armamentarium of treatments. The greatest barrier and frustration to date is the actual identification of patients who harbor the fusion. The dimension of rarity in sarcomas remains difficult to comprehend for both patients and caregivers. Diagnosis of NTRK fusions is complex, particularly in the context of sarcomas and can involve immunohistochemistry as a screening tool but frequently requires fluorescence-in-situ hybridization or next-generation sequencing (NGS) to confirm the diagnosis. SUMMARY: The growing evidence on subtype-specific incidence of NTRK fusions will help to improve strategic prioritization or exclusion of subtypes to reduce the burden of negative testing. Next-generation inhibitors provide potential salvage treatment options for patients failing first-line therapy.

The observational EURACAN prospective clinical registry dedicated to epithelioid hemangioendothelioma: The protocol of an international and collaborative effort on an ultra-rare entity.

INTRODUCTION: Epithelioid hemangioendothelioma (EHE) is an ultra-rare sarcoma, marked by distinctive molecular and pathological features and with a variable clinical behavior. Its natural history is still partially understood, reliable prognostic and predictive factors are lacking and many questions are still open on the optimal management. In the context of EURACAN, a prospective registry specifically dedicated to EHE was developed and launched with the aim of providing, through high-quality prospective data collection, a better understanding of this disease. STUDY DESIGN: Registry-based cohort study including only new cases of patients with a pathological and molecularly confirmed diagnosis of EHE. OBJECTIVES: To improve the understanding of EHE natural history, validate and identify new prognostic and predictive factors, clarify the activity and efficacy of currently available treatment options, describe treatment pattern. METHODS: Settings and participantsIt is an hospital-based registry established in centers with expertise in EHE including adult patients with a new pathological and molecularly confirmed diagnosis of EHE starting from the 1st December 2023. The characteristics of each patient in the facility who meets the above-mentioned inclusion criteria will be collected prospectively and longitudinally with follow-up at cancer progression and / or cancer relapse or patient death. It is a secondary use of data which will be collected from the clinical records. The data collected for the registry will not entail further examinations or admissions to the facility and/or additional appointments to those normally provided for routine patient follow-up. VariablesFull details on patients and disease features, treatment and outcome will be collected, according to common clinical practice guidelines developed and shared with all the contributing centers. In addition, data on potential confounders (e.g. comorbidity; functional status etc.) will also be collected. Statistical methodsThe data analyses will include descriptive statistics and analytical analyses. Multivariable Cox's proportional hazards model and Hazard ratios (HR) for all-cause or cause-specific mortality will be used to determine independent predictors of overall survival, recurrence and progression. RESULTS: The registry has been joined by 21 sarcoma reference centers across EU and UK, covering 10 countries. Patients' recruitment started in December 2023. The estimated completion date is December 2033 upon agreement on the achievement of all the registry objectives. The already established collaboration and participation of EHE patient's associations involved in the project will help in promoting the registry and fostering accrual.

Plasma Sequencing for Patients with GIST-Limitations and Opportunities in an Academic Setting.

Circulating tumor DNA (ctDNA) from circulating free DNA (cfDNA) in GIST is of interest for the detection of heterogeneous resistance mutations and treatment monitoring. However, methodologies for use in a local setting are not standardized and are error-prone and difficult to interpret. We established a workflow to evaluate routine tumor tissue NGS (Illumina-based next generation sequencing) panels and pipelines for ctDNA sequencing in an academic setting. Regular blood collection (Sarstedt) EDTA tubes were sufficient for direct processing whereas specialized tubes (STRECK) were better for transportation. Mutation detection rate was higher in automatically extracted (AE) than manually extracted (ME) samples. Sensitivity and specificity for specific mutation detection was higher using digital droplet (dd)PCR compared to NGS. In a retrospective analysis of NGS and clinical data (133 samples from 38 patients), cfDNA concentration correlated with tumor load and mutation detection. A clinical routine pipeline and a novel research pipeline yielded different results, but known and resistance-mediating mutations were detected by both and correlated with the resistance spectrum of TKIs used. In conclusion, NGS routine panel analysis was not sensitive and specific enough to replace solid biopsies in GIST. However, more precise methods (hybridization capture NGS, ddPCR) may comprise important research tools to investigate resistance. Future clinical trials need to compare methodology and protocols.