Abstract:Objective To retrospectively analyze the clinical efficacy and safety of the combination of orelabrutinib, rituximab and high-dose methotrexate (RMO) regimen in the treatment of newly diagnosed primary central nervous system lymphoma (PCNSL) patients.Methods The data of PCNSL patients treated in our hospital between January 2021 and January 2023 were analyzed retrospectively. All patients received 6 cycles of RMO regimen (rituximab 375 mg·m-2, iv, d1; orelabrutinib 150 mg, qd, po,d1~21; methotrexate 3.5 g·m-2, iv, d2; 3 weeks per cycle) as the induction therapy. Efficacy was assessed by MRI/PET every 2 cycles. After 6 cycles of RMO induction therapy, patients who achieved CR/CRu/PR by MRI and PET received autologous peripheral blood hematopoietic stem cell transplantation as consolidation therapy. Orelabrutinib monotherapy was prescribed as maintenance therapy until the disease progresses. The primary endpoint was the safety and efficacy of this regimen in newly diagnosed PCNSL patients.Results A total of 12 patients were enrolled in this study. The median age of the 12 patients was 58 (45~74) years old. All the patients were pathologically diagnosed as CD20-positive diffuse large B-cell lymphoma (DLBCL). After 4 cycles of RMO therapy, the efficacy was evaluated as complete response (CR) in 4 cases, partial response (PR) in 7 cases, and progressive disease (PD) in 1 case. The objective response rate (ORR) was 91.7%, and the CR rate was 33.3%. After 6 cycles of treatment, the efficacy was evaluated as 8 cases of CR, 2 cases of PR, and 2 cases of PD. The ORR was 83.3%, and the CR rate was 66.6%. The median progression-free survival (mPFS) and the median overall survival (mOS) were not achieved. The 6-month PFS rate was 83.3%, the 6-month OS rate was 100%, the 12-month PFS rate was 64.8%, and the 12-month OS rate was 80.8%. Eight patients underwent gene mutation testing, including 7 cases of MCD type and 1 case of A53 type. After receiving this regimen, the ORR and CR rate of 7 patients with MCD type were 100% and 85.7%, respectively. The main adverse events of RMO regimen was fatigue (25%), and only one patient had ≥3 grade adverse reaction. The most common hematologic toxicity was leukopenia (16.7%), and none of the patients experienced atrial fibrillation and renal failure.Conclusion The RMO regimen is a safe and effective treatment option for newly diagnosed PCNSL patients.