Lack of Apparent Neurotoxicity in Older Patients with Primary Central Nervous System Lymphoma Receiving Long-term Tirabrutinib: Report of 2 Cases

Older patients represent a unique and vulnerable subgroup, requiring careful consideration when determining treatment options. Treatment-related leukoencephalopathy is commonly observed in older patients months to years after receiving radiotherapy and/or methotrexate for primary central nervous system lymphoma (PCNSL). Tirabrutinib is an orally available, highly selective, and potent second-generation Bruton's tyrosine kinase inhibitor (BTKi) approved for treating recurrent/refractory PCNSL in Japan. However, limited studies evaluate the imaging findings in patients receiving tirabrutinib. In this study, we reported 2 cases of older patients with PCNSL who did not develop treatment-related neurotoxicity or leukoencephalopathy after long-term administration of tirabrutinib.