Immunosuppressive effects and clinical response of fludarabine in refractory chronic lymphocytic leukemia

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Abstract
Fludarabine monophosphate is a new adenine nucleoside analogue with a promising efficacy in B-cell chronic lymphocytic leukemia (B-CLL) with response rates, including hematological complete remissions, of 50%–60% in previously treated and 75%–80% in previously untreated patients. Here, the clinical experience with and side effects of fludarabine are reported in 19 patients with refractory CLL (17 B-CLL, 2 T-CLL). All patients were pretreated with one to four different regimens and had progressive disease. Fludarabine was administered at a dosage of 25 mg/m2 daily for 5 days as a 30-minute intravenous infusion. This course was repeated every fifth week. Dosage and time course were adapted to toxicity. 12/18 (67%) evaluable patients achieved partial remissions (PR), 1/18 (6%) had stable disease (SD) and 5/18 (28%) were progressive. The median duration of partial remission until relapse or death was 6 months. Most responses to fludarabine occurred within two treatment courses. Major toxic effects included infections in 11 patients and nausea in 8 (mainly grade 1). Meanwhile, three patients died of progressive disease and 8 of pneumonias or other infections. Two patients had pneumocystis carinii pneumonias and one an aspergillus pneumonia. The high infection rate may be due not only to hypogammaglobulinaemia or fludarabine-induced granulocytopenia but also to a remarkable decrease of CD4+-cells during fludarabine therapy. In one case a tumor lysis syndrome was observed. No CNS toxicity was noted. It is concluded that fludarabine is effective even in patients with advanced chronic lymphocytic leukemia refractory to multiple chemotherapy regimens. However, fludarabine has a remarkable suppressive effect on T-lymphocytes, predominantly CD4+-lymphocytes. Long-term antibiotic prophylaxis is recommended.