Retrospective Evaluation of Rituximab, Methotrexate, Procabazine, Vincristine and Etoposide Followed By Consolidation with Rituximab, Aracytine and Ifosfamide for Elderly Patients with Newly Diagnosed Primary CNS Lymphoma

Introduction
Primary cerebral lymphoma (PCNSL) is an uncommon subtype of diffused large B-cell lymphoma (DLBCL) with a particular poor outcome as compared to systemic DLBCL, especially in elderly. For patients older than 60 years, standard treatment consists of high-dose methotrexate (HD-MTX) chemotherapy without consolidation brain radiotherapy to reduce the risk of leukoencephalopathy. Rituximab in combination with HD-MTX, procarbazine, vincristine followed by HD-cytarabine consolidation is one of standard of treatments for PCNSL patients with a 2-year PFS rate of 47% for patients aged of 60 or older in prospective trial (Morris JCO 2013). Etoposide and Ifosfamide are two drugs that can diffuse across blood-brain barrier and commonly used for relapsed/refractory PCNSL. To improve efficacy of R-MPVA protocol, we developed a new regimen which consisted in adding etoposide and ifosfamide for patients with a newly diagnosed PCNSL aged between 60 and 75 years old.

Patients & Methods

The protocol consisted of 3 cycles every 28 days of rituximab (375mg/m², J1 and J15), MTX (3.5 g/m², J1 and J15), vincristine (1.4 mg/m², J1 and J15), vepeside (100mg/m², J2) and procarbazine (100mg/m², J1-7). Consolidation therapy consisted of 2 cycles every 21 days rituximab (375mg/m², J1) in combination with cytarabine (3g/m², J1-2) with ifosfamide (1.5 g/m², J1-3). Response evaluations were planned after the 3 cycles of induction (R-MPV-VP16) and after consolidation (R-AraC-Ifo). We retrospectively reviewed treatment modalities, toxicities, response and outcome with this protocol and compared results with a matched group of patients with the same range age (60 – 75 years) treated with R-MPVA.

Results
Between 2013 and 2018, 28 PCNSL patients were treated with this protocol. The median age was 67.5 years old (range, 61-74). Poor performance status (PS 3-4) was presented in 9 patients (32%). As compared to 31 patients treated between 2007 and 2018 with R-MPVA, patients treated with intensive protocol were younger (66 vs. 69 years, P=0.01) and had less frequently a poor PS 3-4 (32% vs. 61%, P=0.04). In intent-to-treat analysis, 27 patients received 3 cycles of R-MPV-VP16 but one received only 2. Among them, five patients achieved PR and then received 1 to 2 additional cycles of R-MPV-VP16. Following this induction, 25 patients underwent 2 cycles R-AraC-ifo consolidation, 3 of them did not received ifosfamide for the second cycle because of hematological toxicity and poor PS. One patient in complete response (CR) after whole treatment received high-dose therapy followed by autologous stem cell transplantation. After R-MPV-VP16, 10 patients (36%) achieved CR and 14 partial responses (50%) (PR) as compared to 12 CR (39%) and 12 PR (39%) for patients treated with R-MPVA. After consolidation phase, 23 patients (82%) achieved CR after R-AraC-Ifo as compared to 21 CR (68%) after R-AraC in the historical arm. Differences were not statistically significant. R-MPV-VP16 regimen was associated with favorable toxicity profile with 13 (46%) grade 4 hematological toxicity, 8 (28%) grade 3 and one grade 4 (3%) renal toxicity, 3 (10%) grade 3 and one grade 4 (3%) hepatic toxicity, 6 (21%) grade 3 and 4 grade 4 (14%) and infectious toxicity. With a median follow-up of 46.5 months, patients treated with R-MPV-VP16 followed by R-AraC-ifo had a median event-free survival (EFS) of 33.2 months (95%CI, 17.6 – not reached [NR]) with a 2-year EFS rate of 52%; the median overall survival (OS) was not reached (95%CI, 58.6-NR) with a 2-year OS rate of 70%. With a median follow-up of 94.2 months, patients treated with R-MPVA had a median EFS of 18.3 months with a 2-year EFS rate of 39% (P=0.14, Fig 1); the median OS was 65.9 months with 2-year OS rate of 64% (P=0.33, Fig 1).

Conclusions
In this retrospective analysis of two HD-MTX and HD-AraC based regimens for PCNSL patients aged between 60 and 75 years performed in real-life setting, R-MPVA was more frequently proposed for older patients with a poorer PS. Combination of vepeside to R-MPV and ifosfamide to R-AraC was feasible with a favorable toxicity profile. Despite not statistically different, we observed a trend for an improvement of response rate at the end of treatment (82% vs. 68% of CR) and reduced rate of relapses (2-year EFS rates: 52% vs. 39%) with the intensified protocol. These first results deserve a confirmative larger prospective study of R-MPV-VP16 followed by R-AraC-ifosfamide for elderly PCNSL patients.