Current status and future of relapsed primary central nervous system lymphoma (PCNSL)

The treatment of primary central nervous system lymphoma (PCNSL) has centered around high-dose methotrexate and radiotherapy (RT). Methotrexate administered intra-arterially (IA) with blood-brain barrier disruption (BBBD) and without RT, has been a highly effective treatment with a 5 year survival of 42% without cognitive loss. The purpose of this analysis is to determine responses for patients with relapsed PCNSL treated with second line IA carboplatin-based chemotherapy with BBBD. Between February 1991 and April 2000, 37 relapsed PCNSL patients, most who failed front line therapy with methotrexate based chemotherapy, were treated at Oregon Health & Science University (OHSU) and Hadassah Hebrew University Hospital (HHUH) with IA carboplatin-based chemotherapy with BBBD. Nine patients had prior RT. The mean age was 57.5 years, and all but 1 patient were treated within 8 months after relapse. The median time for survival from first IA carboplatin/BBBD treatment was 6.8 months; however, 7 out of 37 patients survived ≥27 months. Nine patients had radiographic complete response (CR), 4 patients had radiographic partial response (PR), 12 had stable disease (SD), 10 had progressive disease (PD), and 2 were non-evaluable. The median time to failure for patients with CR and PR was 9.1 months. One long-term survivor is alive at 91.0 months from first carboplatin/BBBD treatment. In conclusion, we show that relapsed PCNSL has shown sensitivity to second line IA carboplatin-based chemotherapy with BBBD. We have developed a new protocol using i.v. rituximab prior to BBBD with IA carboplatin, i.v. cyclophosphamide and i.v. etoposide phosphate. The long-term program goal is to consolidate dose-intensive chemotherapy with monoclonal antibody directed radiation. Because patients with recurrent PCNSL commonly continue to relapse even after obtaining a complete response to enhanced chemotherapy treatment, patients who complete or fail the above carboplatin/BBBD treatment regimen will be offered consolidation with radioimmunotherapy using zevalin (Ibritumomab tiuxetan), IDEC-2B8 conjugated with yttrium-90 (⁹⁰Y).