Intraventricular and intravenous treatment of a patient with refractory primary CNS lymphoma using rituximab.

The treatment of primary central nervous system lymphoma (PCNSL) with chemo- and radiotherapy is efficient in terms of tumor response. However, time to tumor progression often is of short duration and leptomeningeal relapse is common. We present a 66-year-old man in third relapse of a CD20-positive PCNSL. After treatment with intravenous and intraventricular administration of the chimeric anti-CD20 monoclonal antibody rituximab, a total clearing of lymphoma cells in the cerebrospinal fluid (CSF) was achieved. There was no change in the size of the parenchymal tumor mass but there was slight improvement of clinical symptoms after therapy. Rituximab infusions (375 mg/m2) were first given systemically on days 1 and 8. Intraventricular injections of rituximab via Ommaya reservoir were given on days 16 (10 mg), 17 (40 mg), 24 (25 mg) and 25 (25 mg). Reversible side effects such as nausea, chills and hypotension were observed only immediately after intraventricular administration of 40 mg rituximab. Antibody levels in CSF were measured at 7 timepoints during and after the treatment period. These data suggest that intraventicular treatment with rituximab is safe and feasible with a potential activity on leptomeningeal tumor manifestation. Efficacy and pharmacokinetics of rituximab in PCNSL should be investigated in future trials.