Timing of NTRK Gene Fusion Testing and Treatment Modifications Following TRK Fusion Status Among US Oncologists Treating TRK Fusion Cancer
Andrew J. Klink, Abhishek Kavati, Awa Gassama, Tom Kozlek, Ajeet Gajra, Ruth Antoine
Abstract
BACKGROUND: Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers with an estimated prevalence of less than 1% across all solid tumors. Tropomyosin receptor kinase inhibitors (TRKis) block the constitutively activated tyrosine receptor kinase (TRK) fusion protein produced in NTRK gene fusion positive (NTRK+) tumors from downstream signaling. Tropomyosin receptor kinase inhibitors are now first-line (1L) or subsequent treatment options for TRK fusion cancers. OBJECTIVE: This study assessed timing of NTRK gene fusion testing and treatment modifications among patients with TRK fusion cancers. PATIENTS AND METHODS: This was a one-time physician questionnaire with a retrospective, multisite patient chart abstraction of oncology practices in the USA. From June to September 2020, medical oncologists from the Oncology Provider Extended Network (OPEN) who treated patients with NTRK+ advanced/metastatic solid tumors abstracted information into electronic case report forms (eCRFs) for adult patients with advanced/metastatic solid tumors and a NTRK+ tumor test result with a known fusion partner. Use of NTRK testing in routine clinical practice among patients with advanced/metastatic solid tumors was assessed. Data included demographic, clinical, and NTRK gene fusion testing characteristics. Responses were summarized using descriptive statistics. RESULTS: Twenty-eight community-based medical oncologists who had managed or treated 148 patients with advanced/metastatic TRK fusion cancer between 01/01/2016 and 12/31/2019 completed the survey. Lung (27%), thyroid (18%), salivary gland (14%), and colorectal (12%) were the most commonly reported tumor types. A majority (68%) tested NTRK status prior to 1L initiation; testing after disease progression on 1L (36%), 2L (25%), and 3L (21%) was also noted. Most oncologists (96%) reported no difficulty interpreting NTRK reports. Nearly all (96%) indicated using next-generation sequencing (NGS) for determining NTRK status. The majority (57%) indicated that age, tumor type, and performance status did not impact NTRK testing decisions. Less than half (46%) include TRKi therapy following NTRK+ determination. NTRK testing guidelines were commonly reviewed by physicians (89%). CONCLUSION AND RELEVANCE: Among patients with advanced/metastatic TRK fusion cancer, medical oncologists reported testing for NTRK fusions at diagnosis or prior to 1L. Future research should elucidate why fewer than half of oncologists surveyed (46%) would not use TRKis after NTRK+ status confirmation, assess clinical practices among NTRK+ patients, and characterize treatment patterns and clinical outcomes in real-world settings.