BACKGROUND: Larotrectinib is the first-in-class, highly selective TRK inhibitor with demonstrated efficacy in various TRK fusion solid tumours. We report the efficacy and safety of larotrectinib in patients with TRK fusion gastrointestinal (GI) cancer. METHODS: Patients with TRK fusion GI cancer from NAVIGATE (NCT02576431) were included. Response was independent review committee (IRC)-assessed per RECIST v1.1. RESULTS: As of July 2023, 44 patients were enrolled. Tumour types included colorectal (CRC
n = 26), pancreatic (n = 7), cholangiocarcinoma (n = 4), gastric (n = 3), and one each of appendiceal, duodenal, oesophageal and hepatic cancers. Of the 26 patients with CRC, 16 (62 %) had known microsatellite instability-high (MSI-H) status. For the 43 IRC-eligible patients, overall response rate was 28 % (95 % confidence interval [CI] 15-44) for all patients and 44 % (95 % CI 24-65) for those with CRC. In patients overall and in those with CRC, median duration of response was 27 months (95 % CI 6-not estimable [NE]) and 27 months (95 % CI 6-NE), median progression-free survival was 6 months (95 % CI 5-9) and 7 months (95 % CI 6-NE), and median overall survival was 13 months (95 % CI 7-29) and 29 months (95 % CI 7-NE), respectively. Grade 3/4 treatment-related adverse events (TRAEs) occurred in seven (16 %) patients. There were no deaths due to TRAEs. CONCLUSION: Larotrectinib demonstrated long durability, extended survival and manageable safety in patients with TRK fusion GI cancer, including those with MSI-H CRC. This supports the wider adoption of next-generation sequencing testing for NTRK gene fusions in patients with GI cancer.