Combined Lorlatinib, Dabrafenib, and Trametinib Treatment for ROS1-Rearranged Advanced Non-Small-Cell Lung Cancer with a Lorlatinib-Induced BRAF V600E Mutation: A Case Report

BACKGROUND: Lorlatinib has been suggested as the therapeutic option for patients with ROS1-rearranged non-small-cell lung cancer (NSCLC) after ROS1 tyrosine kinase inhibitor (TKI) failure. However, the mechanism mediating lorlatinib resistance has not been well elucidated in ROS1-rearranged NSCLC. Post- lorlatinib therapeutic options remain scarce. CASE PRESENTATION: Herein, we describe a 31-year-old female patient with stage IVB ROS1-rearranged NSCLC. She received 2nd line treatment with crizotinib after chemotherapy failure and achieved a partial response lasting for 15 months. An NF1 p.G127Ter mutation emerged as a potential crizotinib resistance mechanism. She subsequently received lorlatinib treatment and achieved a progression-free survival (PFS) of seven months. Based on the emergence of a resistant BRAF V600E, the patient was switched to a combinatorial targeted therapy with lorlatinib, dabrafenib, and trametinib and attained stable disease. She continued the treatment with a time-to-treatment failure of 5.5 months. The acquisition of NRAS p.Q61R and NTRK amplification may confer resistance to the combinatorial targeted therapy. CONCLUSION: To the best of our knowledge, we reported the first case demonstrating that BRAF p.V600E can mediate the lorlatinib resistance in ROS1-rearranged NSCLC and the combinational targeted therapy of ROS1 TKI with dabrafenib and trametinib may serve as an efficient therapeutic option for subsequent treatment.