Background Entrectinib is a potent inhibitor of ROS1 (in addition to TRKA/B/C), designed to effectively penetrate the central nervous system (CNS); brain metastases are common in patients with advanced ROS1 fusion-positive NSCLC. Entrectinib achieves therapeutic levels in the CNS with antitumor activity in multiple intracranial tumor models. We present an updated integrated safety and efficacy analysis from three Phase I/II studies of entrectinib (ALKA-372-001 [EudraCT 2012-000148-88], STARTRK-1 [NCT02097810], STARTRK-2 [NCT02568267]) in patients with locally advanced or metastatic ROS1 fusion-positive NSCLCs.

Methods The analysis included patients with ROS1 inhibitor-naïve NSCLC harboring a ROS1 fusion identified via nucleic acid-based diagnostic platforms. The ROS1 safety-evaluable population included patients with ROS1 fusion-positive NSCLC who received ≥1 dose of entrectinib; the integrated efficacy analysis included patients with at least 6 months of follow-up. Tumor assessments were done at week 4 and every 8 weeks thereafter. Blinded independent central review (BICR), RECIST v1.1 was performed. Primary endpoints by BICR: overall response rate (ORR) and duration of response (DOR). Key secondary endpoints: progression-free survival (PFS), safety. Additional endpoints: intracranial ORR (complete/partial responses), DOR in patients with an intracranial response, PFS in patients with baseline CNS disease.

Results In the ROS1 safety-evaluable population (n=134), at least one treatment-related AE (TRAE) of any grade was seen in 93% of patients. Patients with at least one TRAE by highest grade were: grade 1/2, 59%; grade 3, 31%; grade 4, 4%. There were no grade 5 TRAEs. TRAEs led to dose reduction or discontinuation in 34% and 5% of patients, respectively. In the efficacy-evaluable population (n=53 patients with treatment-naïve, ROS1 fusion-positive NSCLC; median age 53 years, 64% female, 59% never smokers), BICR-assessed ORR was 77% (95% CI 64-88), complete responses n=3 (6%). Median BICR-assessed DOR: 25 mo (95% CI 11-35). Median BICR-assessed PFS: 26 mo (95% CI 16-37) and 14 mo (95% CI 5-NR) for patients without (n=30) and with CNS disease (n=23) at baseline, respectively. In patients with baseline CNS disease (per BICR assessment, n=20), intracranial ORR was 55% (95% CI 32-77) and median intracranial DOR in patients with an intracranial response (n=11) was 13 mo (95% CI 6-not reached).

Conclusion Entrectinib is highly active in patients with ROS1 fusion-positive NSCLC, including those with CNS disease. Entrectinib is well tolerated and has a manageable safety profile.

Citation Format: Alexander Drilon, Fabrice Barlesi, Filippo De Braud, Byoung Chul Cho, Myung-Ju Ahn, Salvatore Siena, Matthew G. Krebs, Chia-Chi Lin, Tom John, Daniel SW Tan, Takashi Seto, Rafal Dziadziuszko, Hendrick-Tobias Arkenau, Christian Rolfo, Jürgen Wolf, Chenglin Ye, Todd Riehl, Susan Eng, Robert C. Doebele. Entrectinib in locally advanced or metastatic ROS1 fusion-positive non-small cell lung cancer (NSCLC): Integrated analysis of ALKA-372-001, STARTRK-1 and STARTRK-2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT192.