To estimate the antitumor activity of 9-aminocamptothecin (9-AC) in patients with recurrent platinum-“resistant” ovarian cancer; and to determine the natur e and degree of toxicity of 9-AC in this cohort of patients. A multicenter phas e II study was conducted by the Gynecologic Oncology Group (GOG). Patients were to receive 9-AC (colloidal dispersion) 25 μg/m2/h (600 μg/m2/day) IV over 120 h (5 days) beginning days 1 and 8. Dose adjustment was permitted for toxicity. This schedule was repeated every 21 days until disease progression or unacceptab le adverse events. Hematopoietic growth factor support was used as necessary. Fr om January 1999 to December 2000, 29 member institutions of the GOG enrolled 58 patients. Two patients received no therapy; thus, 56 (97%) were evaluable. Medi an age was 61 (range: 33-81) years. A median of four (range: 1-32) courses of 9-AC was administered. The most frequent grade 3 or 4 toxicities were neutropen ia in 46%, leukopenia in 37%, gastrointestinal in 29%, anemia in 25%, and th rombocytopenia in 21%. There was one possible treatment-related death. There w ere four (7%) complete and four (7%) partial responses, for an overall respons e rate of 14%. Eighteen (32%) patients had stable disease, 22 (39%)-progress ed, and response could not be assessed in 8 (14%). The 9-AC at this dose and s chedule showed limited activity comparable to that seen with other agents in pla tinum-resistant ovarian or primary peritoneal cancer. To estimate the antitumor activity of 9-aminocamptothecin (9-AC) in patients with recurrent platinum- “resistant ” ovarian cancer; and to determine the natur e and degree of toxicity of 9-AC in this cohort of patients. A multicenter phas e II study was conducted by the Gynecologic Oncology Group (GOG). Patients were asked to receive 9-AC (colloidal dispersion) 25 μg / m2 / h (600 μg / m2 / day) IV over 120 h 1 and 8. Dose adjustment was permitted for toxicity. This Schedule was repeated every 21 days until disease progression or unacceptab le adverse events. Hematopoietic growth factor support was used as necessary. Fr om January 1999 to December 2000, 29 member institutions of the GOG enumerated 58 patients. Two patients received no therapy; thus, 56 (97%) were evaluable. Median was 61 (range: 33-81) years. was administered. The most frequent grade 3 or 4 toxicities were neutropen ia in 46%, leukopenia in 37%, gastrointesti There was one possible treatment-related death. There w ere four (7%) complete and four (7%) partial responses, for an overall respons e rate of 14%. The Eighteen (32%) patients had stable disease, 22 (39%) - progress ed, and response could not be assessed in 8 (14%). The 9-AC at this dose and s chedule showed limited activity comparable to that seen with other agents in pla tinum-resistant ovarian or primary peritoneal cancer.