The current study was performed to determine the maximum tolerated dose (MTD), toxicity, and outcome of infusional 5 bromo-2'-deoxyuridine (bromodeoxyuridine; BUdR) given with accelerated fractionation whole brain radiation therapy (WBRT) after chemotherapy for the treatment of primary central nervous system lymphoma (PCNSL).
Twelve patients with untreated and histologically confirmed PCNSL were entered on the study between 1994 and 1996. Chemotherapy was comprised of one course of IDHAP plus high-dose methotrexate (HD-MTX). IDHAP is comprised of idarubicin at a dose of 1.5 mg/m2/day × 4 days intravenously by continuous infusion (i.v. CI), dexamethasone at a dose of 40 mg i.v. on Days 1–5, cytosine arabinoside at a dose of 2000 mg/ m2 i.v. on Day 5 after cisplatin, and cisplatin at a dose of 25 mg/m2/day × 4 days i.v. CI. HD-MTX was given at a dose of 3.5 g/m2 i.v. between Day 10 and Day 14 after IDHAP. BUdR was given as an i.v. CI over 48 hours, 2–3 days prior to WBRT and then weekly during WBRT. Dose escalation started at 1.5 g/m2/day for Cohort 1 with subsequent increments of 0.3 g/m2/day. The WBRT dose was 45 grays (Gy) at a dose of 1.5 Gy twice a day, 5 days per week. Neurocognitive testing was performed before, during, and after treatment.
Nine of 12 patients entered on the study received BUdR. One of 3 patients in Cohort 1 developed leukoencephalopathy (LEP), a dose-limiting toxicity (DLT), within 2 months of the completion of therapy. Therefore, the next cohort received the same dose level. Because no toxicity was observed in Cohort 2, the third cohort received a BUdR dose of 1.8 g /m2/day. Shortly after completing enrollment in Cohort 3, 3 more patients developed LEP, including 2 from Cohort 1 who had received a dose of 1.5 g/m2/day. Thus, DLT occurred at a dose of 1.5 g/m2/day, the starting level in the current study. As a result, the trial was stopped. Eight of 12 patients achieved a complete response, 3 achieved a partial response, and 1 patient died before response assessment.
Hyperfractionated WBRT with concurrent BUdR after chemotherapy was found to result in modest disease control but has unacceptable neurotoxicity. Cancer 2003;98:1021–8. © 2003 American Cancer Society.