P17.14.B A RETROSPECTIVE STUDY OF THE BTK-INHIBITOR TIRABRUTINIB FOR THE TREATMENT OF RECURRENT/REFRACTORY PRIMARY CNS LYMPHOMA

Abstract BACKGROUND Tirabrutinib is a highly selective oral Bruton’s tyrosine kinase inhibitor of the second generation that has been approved for the treatment of recurrent/refractory primary central nervous system lymphoma (PCNSL) in Japan. We evaluated tirabrutinib investigations that were conducted at a single institution. MATERIAL AND METHODS Our institutional review board approved this single center retrospective study. Thirty-five patients with recurrent or refractory PCNSL treated with tirabrutinib at our institution between 2020 and 2025 were included. Data concerning the patient’s age, gender, imaging results, pathological findings, including immunostaining results, and treatment details, encompassing chemotherapy and radiation therapy, was acquired from medical records. This study also aimed to address the long-term imaging burden caused by radiation after treatment. RESULTS Tirabrutinib was administered to 17 patients with recurrent cases (20-85 years old, median 70 years old, 10 males and 7 females), 18 with refractory cases (58-87 years old, median 74 years old, 12 males and 6 females). Four male patients received rechallenge with tirabrutinib against re-relapsed. We assessed the effectiveness of tilabrutinib and observed complete response (CR) in 13 cases, partial response (PR) in 2 case, stable disease (SD) in 1 case, and progressive disease (PD) in 2 case among refractory patients. In recurrent cases, we observed CR in 11 cases, PR in 1 case, SD in 3 cases, and PD in 2 cases. In the rechallenge for re-relapsed cases, we noted a CR in 2 cases, SD in 1 case, and PD in 1 case. The treatment failure free survival following beginning of tirabrutinib was 7.9 months for refractory cases and 14.2 months for recurrent cases. The overall survival was 25 months for refractory cases and 32.4 months for recurrent cases. One patient each experienced CTCAE grade 3 interstitial pneumonia or liver failure, both of which improved after discontinuing the medication. Four patients exhibited grade 1-2 skin rashes. Elderly patients with refractory PCNSL without radiation therapy did not develop treatment-related neurotoxicity or leukoencephalopathy after long-term administration of tirabrutinib. CONCLUSION In real-world settings, tirabrutinib has shown to be an effective and well-tolerated treatment for recurrent or refractory PCNSL.