iMARIX for primary and secondary central nervous system lymphomas.

7086 Background: The Bruton tyrosine kinase inhibitor (BTKi) ibrutinib is used in relapsed/resistant central nervous system (CNS) lymphoma because it can cross the blood-brain barrier and is effective as a single drug. Its efficacy has been demonstrated in combination with rituximab and high-dose methotrexate. CNS lymphomas are aggressive lymphomas, and responses to single-agent therapies are generally poor or insufficient. Also, even well-established agents used in lymphoma treatment may sometimes be unavailable worldwide, and drug restrictions may be experienced worldwide. Thiotepa is one of these agents. In this case series, we summarized the iMARIX treatment in which we used ibrutinib in combination with high-dose methotrexate, cytarabine and rituximab instead of thiotepa for the treatment of primary/secondary CNS lymphomas. Methods: The participants diagnosed with primary/secondary CNS lymphoma and treated between August 2022 and December 2025, received rituximab 375 mg/ m2 (one day), 3.5 g/m2 methotrexate (one day), 2x2 g/ m2 cytarabine (two days), and ibrutinib 560 mg/day in each course. Ibrutinib was continued provided that platelet count is over 30.000/ mm3 and neutrophil count is over 500/ mm3. Patient data were collected retrospectively. Results: 17 patients were treated with iMARIX protocol during the study course. Male/ female ratio was 8 (47%)/ 9 (53%) and the median age was 53 (21- 71). 8 (47 %) of the participants had primary whereas 9 (53 %) had secondary CNS lymphoma. 4 (23.5%) participants died of either relapse or sepsis during the study period. The median overall survival was 16.3 months (4- 31.6). 13 (76,5 %) patients underwent consolidative autologous stem cell transplantation (ASCT). One patient experienced atrial fibrillation due to ibrutinib use. One patient experienced relapse after ASCT and was further treated with allogeneic stem cell transplantation. Conclusions: Although our patient series is small, the results suggest that the combination of ibrutinib with high-dose methotrexate, rituximab and cytarabine is a combination that may yield good clinical results with an acceptable tolerance and adverse effect profile.