Recommended testing algorithms for NTRK gene fusions in pediatric and selected adult cancers: Consensus of a Singapore Task Force

NTRK gene fusion testing and management in lung cancer

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are recurrent oncogenic drivers found in a variety of solid tumours, including lung cancer. Several tropomyosin receptor kinase (TRK) inhibitors have been developed to treat tumours with NTRK gene fusions. Larotrectinib and entrectinib are first-generation TRK inhibitors that have demonstrated efficacy in patients with TRK fusion lung cancers. Genomic testing is recommended for all patients with metastatic non-small cell lung cancer for optimal drug therapy selection. Multiple testing methods can be employed to identify NTRK gene fusions in the clinic and each has its own advantages and limitations. Among these assays, RNA-based next-generation sequencing (NGS) can be considered a gold standard for detecting NTRK gene fusions; however, several alternatives with minimally acceptable sensitivity and specificity are also available in areas where widespread access to NGS is unfeasible. This review highlights the importance of testing for NTRK gene fusions in lung cancer, ideally using the gold-standard method of RNA-based NGS, the various assays that are available, and treatment algorithms for patients.

Beyond Clinical Trials: Understanding Neurotrophic Tropomyosin Receptor Kinase Inhibitor Challenges and Efficacy in Real-World Pediatric Oncology

PURPOSE

Our study aimed to explore real-world treatment scenarios for children and adolescents with neurotrophic tropomyosin receptor kinase (NTRK)-fused tumors, emphasizing access, responses, side effects, and outcomes.

PATIENTS AND METHODS

Pooled clinical data from 17 pediatric cases (11 soft-tissue sarcomas, five brain tumors, and one neuroblastoma) treated with larotrectinib and radiologic images for 14 patients were centrally reviewed. Testing for gene fusions was prompted by poor response to treatment, tumor progression, or aggressiveness.

RESULTS

Six different NTRK fusion subtypes were detected, and various payment sources for testing and medication were reported. Radiologic review revealed objective tumor responses (OR) in 11 of 14 patients: Complete responses: two; partial responses: nine; and stable disease: three cases. Grades 1 or 2 Common Terminology Criteria for Adverse Events adverse effects were reported in five patients. Regarding the entire cohort's clinical information, 15 of 17 patients remain alive (median observation time: 25 months): four with no evidence of disease and 11 alive with disease (10 without progression). One patient developed resistance to the NTRK inhibitor and died from disease progression while another patient died due to an unrelated cause.

CONCLUSION

This real-world study confirms favorable agnostic tumor OR rates to larotrectinib in children with NTRK-fused tumors. Better coordination to facilitate access to medication remains a challenge, particularly in middle-income countries like Brazil.

The significance of tissue-agnostic biomarkers in solid tumors: the more the merrier?

INTRODUCTION

To date, several emerging biomarkers have gained considerable interest in the field of predictive molecular oncology. The advent of precision medicine has led to the development of innovative drugs targeting rare molecular pathways independently from histology, defined as tissue-agnostic drugs.

AREAS COVERED

Although there is a lot of promise for this new tissue-agnostic model in the oncological scenario, crucial issues from both the diagnostic and therapeutic standpoint are emerging. This review aims to critically examine the role of tissue-agnostic biomarkers in different solid tumors, focusing on the prevalence and methods of detection of agnostic biomarkers together with drug approvals to guide clinicians in this evolving landscape.

EXPERT OPINION

To strengthen the framework for tissue-agnostic approvals, the dialogue between regulatory, industrial, and academic parties should be intensified. Critical questions include the development of an efficient network system that can overcome the heterogeneity of patients' inclusion criteria along with the increasingly difficult interpretation of next-generation sequencing (NGS) profiling technologies. Cost-effectiveness and risk-benefit studies are needed in the national context considering the modalities of access to diagnostic tests and reimbursement of treatments.

NTRK fusions in solid tumours: what every pathologist needs to know

Fusions involving the Neurotrophic tropomyosin receptor kinase (NTRK) gene family (NTRK1, NTRK2 and NTRK3) are targetable oncogenic alterations that are found in a diverse range of tumours. There is an increasing demand to identify tumours which harbour these fusions to enable treatment with selective tyrosine kinase inhibitors such as larotrectinib and entrectinib. NTRK fusions occur in a wide range of tumours including rare tumours such as infantile fibrosarcoma and secretory carcinomas of the salivary gland and breast, as well as at low frequencies in more common tumours including melanoma, colorectal, thyroid and lung carcinomas. Identifying NTRK fusions is a challenging task given the different genetic mechanisms underlying NTRK fusions, their varying frequency across different tumour types, complicated by other factors such as tissue availability, optimal detection methods, accessibility and costs of testing methods. Pathologists play a key role in navigating through these complexities by determining optimal approaches to NTRK testing which has important therapeutic and prognostic implications. This review provides an overview of tumours harbouring NTRK fusions, the importance of identifying these fusions, available testing methods including advantages and limitations, and generalised and tumour-specific approaches to testing.

Brazilian Expert Consensus for NTRK Gene Fusion Testing in Solid Tumors

Oncogenic neurotrophic tropomyosin receptor kinase gene fusions occur in less than 1% of common cancers. These mutations have emerged as new biomarkers in cancer genomic profiling with the approval of selective drugs against tropomyosin receptor kinase fusion proteins. Nevertheless, the optimal pathways and diagnostic platforms for this biomarker's screening and genomic profiling have not been defined and remain a subject of debate. A panel of national experts in molecular cancer diagnosis and treatment was convened by videoconference and suggested topics to be addressed in the literature review. The authors proposed a testing algorithm for oncogenic neurotrophic tropomyosin receptor kinase gene fusion screening and diagnosis for the Brazilian health system. This review aims to discuss the latest literature evidence and international consensus on neurotrophic tropomyosin receptor kinase gene fusion diagnosis to devise clinical guidelines for testing this biomarker. We propose an algorithm in which testing for this biomarker should be requested to diagnose advanced metastatic tumors without known driver mutations. In this strategy, Immunohistochemistry should be used as a screening test followed by confirmatory next-generation sequencing in immunohistochemistry-positive cases.

Prevalence of NTRK Fusions in Canadian Solid Tumour Cancer Patients

INTRODUCTION

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions occur in ~ 0.3% of all solid tumours but are enriched in some rare tumour types. Tropomyosin receptor kinase (TRK) inhibitors larotrectinib and entrectinib are approved as tumour-agnostic therapies for solid tumours harbouring NTRK fusions.

METHODS

This study investigated the prevalence of NTRK fusions in Canadian patients and also aimed to help guide NTRK testing paradigms through analysis of data reported from a national clinical diagnostic testing program between September 2019 and July 2021.

RESULTS

Of 1,687 patients included in the final analysis, NTRK fusions were detected in 0.71% (n = 12) of patients representing salivary gland carcinoma (n = 3), soft tissue sarcoma (n = 3), CNS (n = 3), and one in each of melanoma, lung, and colorectal cancer. All three salivary gland carcinomas contained ETV6-NTRK3 fusions. Thirteen (0.77%) clinically actionable incidental findings were also detected. Two of the 13 samples containing incidental findings were NTRK fusion-positive (GFOD1-NTRK2, FGFR3-TACC3 in a glioblastoma and AFAP1-NTRK2, BRAF c.1799T>A in a glioma). The testing algorithm screened most patient samples via pan-TRK immunohistochemistry (IHC), whereas samples from the central nervous system (CNS), pathognomonic cancers, and confirmed/ putative NTRK fusion-positive samples identified under research protocols were reflexed straight to next-generation sequencing (NGS).

CONCLUSION

These findings highlight the benefit and practicality of a diagnostic testing program to identify patients suitable for tumour-agnostic TRK inhibitor therapies, as well as other targeted therapies, due to clinically actionable incidental findings identified. Collectively, these findings may inform future guidance on selecting the appropriate testing approach per tumour type and on optimal NTRK testing algorithms.

Biomarkers in the development of individualized treatment regimens for colorectal cancer

Introduction

Colorectal cancer (CRC) is the third most common and second most deadly malignancy in the world with an estimated 1. 9 million cases and 0.9 million deaths in 2020. The 5-year overall survival for stage I disease is 92% compared to a dismal 11% in stage IV disease. At initial presentation, up to 35% of patients have metastatic colorectal cancer (mCRC), and 20–50% of stage II and III patients eventually progress to mCRC. These statistics imply both that there is a proportion of early stage patients who are not receiving adequate treatment and that we are not adequately treating mCRC patients.

Body

Targeted therapies directed at CRC biomarkers are now commonly used in select mCRC patients. In addition to acting as direct targets, these biomarkers also could help stratify which patients receive adjuvant therapies and what types. This review discusses the role of RAS, microsatellite instability, HER2, consensus molecular subtypes and ctDNA/CTC in targeted therapy and adjuvant chemotherapy.

Discussion

Given the relatively high recurrence rate in early stage CRC patients as well as the continued poor survival in mCRC patients, additional work needs to be done beyond surgical management to limit recurrence and improve survival. Biomarkers offer both a potential target and a predictive method of stratifying patients to determine those who could benefit from adjuvant treatment.

Overview of predictive and prognostic biomarkers and their importance in developing a clinical pharmacology treatment plan in colorectal cancer patients

INTRODUCTION

Colorectal cancer (CRC) is the second most common cause of cancer-related death worldwide. Although overall survival for CRC patients has improved with earlier screening, survival continues to vary substantially across stages. Also, while the introduction of targeted therapies, including VEGF and EGFR inhibitors, has contributed to improving survival, better tools are needed to optimize patient selection and maximize therapeutic benefits. Emerging biomarkers can be used to guide pharmacologic decision-making, as well as monitor treatment response, clarify the need for adjuvant therapies, and indicate early signs of recurrence. This is a narrative review examining the current and evolving use of predictive and prognostic biomarkers in colorectal cancer.

AREAS COVERED

Areas covered include mutations of the MAPK (KRAS, BRAF) and HER2 pathways and their impacts on treatment decisions. In addition, novel methods for assessing tumor mutations and tracking treatment responses are examined.

EXPERT OPINION

The standard of care pathway for staging, and treatment selection and surveillance, of CRC will expand to include novel biomarkers in the next 5 years. It is anticipated that these new biomarkers will assist in decision-making regarding selection of targeted therapies and, importantly, in risk stratification for treatment decisions in patients at high risk for recurrence.