Abstract CT206: Larotrectinib (L) in patients (pts) with solid tumors with NTRK1/2/3 amplification (amp): Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) Study

Abstract Background: TAPUR is a phase II basket study evaluating antitumor activity of commercially available targeted agents in pts with advanced cancers with specific genomic alterations. Results in a cohort of pts with solid tumors with NTRK1/2/3 amp treated with L are reported. Methods: Eligible pts had measurable disease, ECOG performance status (PS) 0-2, adequate organ function, and no remaining standard treatment (tx) options. Genomic testing was performed in CLIA-certified, CAP-accredited site selected labs. Amp cut-offs were defined per NGS providers. Tumors must not have had NTRK fusions. L dosing was one 100 mg capsule or oral solution twice daily until disease progression or unacceptable toxicity. Primary endpoint was disease control (DC) per investigator defined as objective response (OR) or stable disease (SD) of at least 16+ weeks (wks) duration (SD16+) per RECIST v1.1. Simon 2-stage design tested the null DC rate of 20% vs. 45% (power = 0.85, α=0.10). If ≥2 of 8 pts in stage 1 had DC, 13 more pts were enrolled; otherwise, the cohort was closed for futility. Secondary endpoints were OR, progression-free survival (PFS), overall survival (OS), duration of response and SD, and safety. Results: 8 pts with solid tumors (breast [n=3], soft tissue sarcoma [n=2], head and neck [n=1], non-small cell lung cancer (LC) [n=1], small cell LC [n=1]) with NTRK1 amp (n=5), NTRK2 amp (n=1), NTRK1 amp and mutation (mut) (n=1), and NTRK1 amp and NTRK3 mut (n=1) were enrolled. All pts were evaluable for efficacy. Table shows demographics and outcomes. SD16+ was observed in 1 pt with myxoliposarcoma and NTRK1 amp for a DC rate of 13% (1-sided 90% CI, 1 to 100) and an OR rate of 0% (95% CI, 0 to 37). Duration of SD in 1 pt was 24 wks. The null DC rate was not rejected (p=0.83). No pts had grade 3-5 tx-related adverse or serious adverse events. Conclusions: L did not meet prespecified criteria to declare a signal of activity in pts with solid tumors with NTRK amp. Citation Format: Jordi Rodon, Michael Rothe, Elizabeth Garrett-Mayer, Nithin Rohatgi, Alvaro G. Menendez, Leighton A. Elliott, Andrew Gregory, Abigail Gregory, Dominique C. Hinshaw, Gina N. Grantham, Susan Halabi, Richard L. Schilsky. Larotrectinib (L) in patients (pts) with solid tumors with NTRK1/2/3 amplification (amp): Results from the Targeted Agent and Profiling Utilization Registry (TAPUR) Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr CT206.