BACKGROUND: Used as single agents, paclitaxel and topotecan have demonstrated promising activity in treating patients with relapsed aggressive non-Hodgkin's lymphoma (NHL). We conducted a phase II clinical trial to investigate the activity and tolerability of the combination of both drugs. PATIENTS AND METHODS: Patients with refractory or relapsed aggressive NHL who had previously been treated with a maximum of two prior chemotherapeutic regimens were given intravenous infusions of paclitaxel 200 mg/m2 over three hours on day one and topotecan 1 mg/m2 over 30 minutes daily from days one to five. All patients received daily subcutaneous injections of filgrastim (granulocyte colony-stimulating factor) 5 microg/kg starting 24 hours after the last dose of chemotherapy until neutrophil recovery. Treatments were repeated every three weeks for a maximum of six courses. Patients who achieved partial remission or complete remission (CR) after at least two courses were offered stem cell transplantation, if eligible. RESULTS: Of the 71 patients eligible for this trial, 66 (93%) were evaluable for treatment response. The median age was 53 years (range 23 to 74 years). Thirty-six percent of the patients had previously been treated with ara-C/platinum-based regimens, and 48% failed to achieve CR after primary induction therapy. Sixty-seven percent of the patients had elevated lactate dehydrogenase levels at the time of treatment initiation. The overall response rate was 48% (95% confidence interval (95% CI): 36%-61%). Patients who had primary refractory disease had a response rate of 31%, compared with 65% for patients who did not. Similarly, the response rate of patients who failed to achieve CR after their most recent previous therapy was 37%, compared with a 65% response rate in patients who relapsed from a first or second CR. The median duration of response was six months. A total of 199 courses were given, with a median of three courses per patient. Neutropenia at levels < or = 500 leukocytes per microliter was observed after 32% of the courses, and thrombocytopenia at levels < or = 20,000 platelets per microliter was observed after 17% of the courses. Grade 3-4 neutropenic fever occurred after 6% of the courses. Non-hematologic toxic effects were predominantly grade 1-2. CONCLUSION: The combination of paclitaxel and topotecan is an effective first or second line salvage therapy for patients with relapsed or refractory aggressive NHL who had prior anthracycline- or platinum-based chemotherapy.