The role of topoisomerase-I inhibitors in the treatment of non-Hodgkin's lymphoma.

First-line chemotherapy and/or radiotherapy can achieve disease-free survival in 30% to 75% of patients with non-Hodgkin's lymphomas (NHL), a diverse group of hematologic malignancies, depending on disease stage. However, as many as 50% of patients with advanced-stage NHL either do not achieve an Initial clinical response or subsequently relapse. Topotecan, a topoisomerase-I inhibitor, is considered a potential treatment for NHL. The efficacy of topotecan, alone and in combination with paclitaxel, in the treatment of patients with relapsed NHL has recently been Investigated. In a clinical study of topotecan as a single agent, patients with aggressive NHL who had received only 1 prior chemotherapy regimen had a 43% response rate, and similar patients with Indolent NHL had a 40% response rate. A combination of paclitaxel and topotecan has been shown to have efficacy in a phase 11 trial, with overall response rates of 27% in patients with primary refractory NHL and 72% in patients with relapsed NHL. Based on these promising early results, further Investigation of topotecan in the treatment of NHL is warranted.