Pts received larotrectinib 100 mg twice a day (BID) except for one pt who received 150 mg BID in the phase 1 trial (NCT02122913)….All pts had ETV6-NTRK3 gene fusions....Larotrectinib demonstrated rapid and durable efficacy with a favourable safety profile in pts with TRK fusion SGTs. These data highlight the importance of identifying NTRK gene fusions in pts with SGTs.

Patients with TRK fusion-positive salivary gland cancer treated with larotrectinib were identified from two clinical trials (NCT02122913 and NCT02576431)....All 24 patients had an ETV6-NTRK3 gene fusion....Larotrectinib demonstrated robust and durable efficacy in patients with TRK fusion-positive salivary gland tumors of various histologies, and a favorable safety profile.

Patients received larotrectinib 100 mg twice a day (BID) except for 1 patient who received 150 mg BID in the phase 1 trial (NCT02122913). All 22 patients had ETV6-NTRK3 gene fusions. The objective response rate was 91% (95% confidence interval [CI] 71–99%). Complete response was seen in 3 patients (14%), partial response in 16 (73%), and partial response awaiting confirmation in 1 (5%). Two patients (9%) with secretory carcinoma had progressive disease. Over a median follow-up of 22 months, median duration of response (DoR) was 35.2 months (95% CI 19.8–not estimable [NE]) with a 12-month DoR rate of 94% (95% CI 83–100%). Median progression-free survival was 36.8 months (95% CI 25.7–NE) at a median follow-up of 23.7 months. Median overall survival (OS) was not reached, and the 12-month OS rate was 95% over a median follow-up of 25.6 months.

With ETV6-NTRK3 fusion confirmed, the patient’s diagnosis was revised to metastatic secretory carcinoma of the salivary gland, and treatment with pan-Trk inhibitor Larotrectinib (100 mg twice daily) initiated. After 8 months of treatment, CT and MRI scans showed partial remission with pulmonary and skeletal metastases of reduced size.