Long-term efficacy and safety of larotrectinib in patients with tropomyosin receptor kinase (TRK) fusion lung cancer

9056 Background: Neurotrophic tyrosine receptor kinase ( NTRK) gene fusions are oncogenic drivers in a variety of tumor types, including lung cancer. Larotrectinib is a highly selective, central nervous system (CNS)-active TRK inhibitor that demonstrated rapid, deep, and durable responses in patients (pts) with TRK fusion lung cancer (Drilon et al. ASCO 2022) and is considered a preferred first-line therapy option for these pts (Owen et al. J Clin Oncol 2022). We report updated data from a larger cohort with longer follow-up. Methods: Pts with TRK fusion lung cancer enrolled in 2 larotrectinib clinical trials (NCT02576431 and NCT02122913) were included in this analysis. Larotrectinib was administered at 100 mg twice daily, and response was assessed by independent review committee (IRC) per RECIST v1.1. Results: As of July 20, 2022, 30 pts with a median age of 55.5 years (range 25–81) with TRK fusion lung cancer enrolled, including 12 pts with CNS metastases at baseline. The gene fusions involved NTRK1 (n = 24; 80%) or NTRK3 (n = 6; 20%). Pts received a median of 2 prior lines of systemic therapies, with 20 pts (67%) receiving ≥2. Among 27 pts eligible for IRC assessment, the objective response rate (ORR) was 74% (95% CI 54–89): 3 complete responses, 17 partial responses (PR), 4 stable disease (SD), 2 progressive disease (PD), and 1 not evaluable. Among the 12 pts with baseline CNS metastases, the ORR was 67% (95% CI 35–90): 8 PR, 2 SD, and 2 PD. The median time to response for all responders was 1.8 months. Median duration of response (DoR) was 33.9 months (95% CI 9.5–not estimable [NE]); median follow-up was 22.9 months. Median progression-free survival (PFS) was 33.0 months (95% CI 11.3–NE); median follow-up was 24.7 months. Median overall survival (OS) was 39.3 months (95% CI 17.2–NE); median follow-up was 23.1 months. For the 12 pts with CNS metastases, the medians for DoR, PFS, and OS were 9.5, 9.9, and 19.4 months, with median follow-ups of 17.4, 19.3, and 22.2 months, respectively. Duration of treatment for all pts evaluable per IRC ranged from 0.3+ to 75.2+ months. At data cut-off, 10 pts had progressed, with 6 continuing treatment post-progression for ≥4 weeks due to continued clinical benefit. Treatment-related adverse events (TRAEs) were predominantly Grade 1–2. Grade 3–4 TRAEs were reported in 5 pts (2 each increased aspartate aminotransferase, increased weight; 1 each increased alanine aminotransferase, myalgia, hypersensitivity). There were no treatment discontinuations due to TRAEs. Conclusions: In this larger dataset with longer follow-up, larotrectinib continued to demonstrate rapid and durable responses, extended survival, and favorable long-term safety in pts with advanced TRK fusion lung cancer, including those with CNS metastases. These results support the wider adoption of next-generation sequencing testing for NTRK1–3 gene fusions in pts with lung cancer. Clinical trial information: NCT02576431 , NCT02122913 .