Tag-n-trak study: Preliminary analysis of an unselected biobank tumors with NTRK fusion transcript, the French SFCE society contribution.

Abstract

10540 Background: NTRK ( Neurotrophic receptor tyrosine kinase) fusion transcript was initially described in infantile fibrosarcoma (IFS) and is now known to be present in many other rare types of tumor with a lower incidence. The main objective of the study is to describe the presentation and outcome of unselected tumors with NTRK fusion transcript (NTRK-FTT) to better consider the role of TRK inhibitors (TRKi) in such entities. Methods: We selected patients (pts) from the Institut Curie biobank (adults and children) with NTRK-FTT and which were assessed by RT-qPCR then RNA sequencing in a prospective or retrospective process, between 2001 and 2019. Results: We identified 62 NTRK-FTT among 2119 screened tumors (2.2 cases/year with RT-qPCR and 6.9 cases/year with RNA seq after 2016), NTRK3 (44 cases) (including 41 NTRK3-ETV6), NTRK2 (9) or NTRK1 (9). Most of pts had under 2 years (y) (74%) and only 7 pts were adults. We report preliminary analysis of clinical observation for the first 27 pts. Median age was 0.4 y [0-60.2]. Pathologic diagnosis was IFS (12 cases), various CNS tumors (4), atypical teratoid rhabdoid tumor (1), myofibroblastic inflammatory tumor (2), benign tumors (3), cellular congenital mesoblastic nephroma (2), lipofibromatosis like neural tumor, myxoïd liposarcoma, unclassifiable sarcoma (1 each). Two pts had metastatic tumors. Among all, 22 had surgery (1 mutilating), 15 chemotherapy, 4 radiotherapy, and 5 received TRKi, as second line treatment (2 pts) or ≥ third line (3 pts). After a median follow-up of 50 months [range, 1-155], 20/27 pts remained in complete remission, 3 had stable residue, and 4 had progressive disease (associated to 1 disease-related and 1 toxic deaths). Five-year OS is 88% [95%CI, 73.5-100] and 5y-EFS 59.5% [95%CI, 41.7-84.9]. Conclusions: This descriptive study showed that NTRK-FTT is rare (2.9%), encompasses a variety of different histotypes (n = 14). Systematic RNA sequencing allowed to depict 3.5 times more NTRK-FTT than targeted RT-qPCR. Overall outcome is favorable despite frequent tumor events. According to tumor type and the uncertainties regarding the long-term side effects of TRKi, the benefit/risk ratio must be carefully evaluated before using these drugs in first line.