Complete and durable regression of leptomeningeal involvement during lorlatinib treatment in a patient with lung cancer.

Metastatic spread to the central nervous system (CNS) is frequent in anaplastic lymphoma kinase ( ALK )-rearranged non-small cell lung cancer (NSCLC) and has an important impact on patient prognosis and quality of life. Leptomeningeal involvement may occur in up to 10% of cases of ALK-positive NSCLC. Lorlatinib is a third-generation ALK inhibitor that has excellent CNS penetrability and demonstrated its efficacy both in pretreated and treatment-naive patients. Herein, we present the case of a 34-year-old patient diagnosed with stage IV ALK-rearranged NSCLC who received two lines of ALK inhibitors (crizotinib followed by alectinib) and several courses of brain stereotactic ablative radiotherapy until leptomeningeal involvement was detected. Third-line lorlatinib was then administered, and 2 months later encephalic MRI documented complete regression of the leptomeningeal involvement that is still maintained after 36 months while treatment with lorlatinib is still ongoing with good tolerability. To the best of our knowledge, this is the longer intracranial response reported in the literature, underlining the importance of the most appropriate choice of systemic treatments and their integration with loco-regional approaches to improve outcomes.