Kei Morikawa

Anaplastic lymphoma kinase (ALK) fusion gene‐positive lung cancer often shows brain metastasis at initial diagnosis or during the course of treatment. However, molecular‐targeted drugs are known to pass through the blood–brain barrier and present positive effects for central nervous system lesions. There are few reports suggesting how effective molecular‐targeted drug therapy alone is for brain metastasis lesions of ALK fusion‐positive lung cancer, especially after the first use of ALK‐tyrosine kinase inhibitor (TKI) or for bulky brain metastases. A patient in his mid‐fifties with stage IV pleural dissemination developed brain metastases after 10 years of crizotinib use, but showed a complete response after switching to brigatinib. Moreover, a patient in her early sixties with stage III recurrent large brain metastases 5 years after chemoradiation therapy experienced dramatic tumor shrinkage with brigatinib. In each case of ALK fusion gene‐positive lung cancer with brain metastases, brigatinib showed a high efficacy and was well‐tolerated after previous ALK‐TKI and for bulky lesions.