JACKSONVILLE, FloridaAn encouraging study reported at the 38th Annual
Meeting of the American Society of Clinical Oncology (abstract 206) suggests
that irinotecan (CPT-11, Camptosar) may prove valuable in advanced breast
cancer. The randomized multicenter phase II study by the North Central
Cancer Treatment Group was spearheaded by Edith Perez, MD, professor of
medicine, Mayo Clinic, Jacksonville, Florida.
The study included 103 heavily pretreated metastatic breast cancer
patients with visceral and soft tissue metastases. Over half of the patients
had been pretreated with both anthracyclines and taxanes, and about one
third had received two treatment regimens for metastatic disease.
The patients received irinotecan as a single agent either on a weekly
basis (100 mg/m² for 4 weeks with 2 weeks off) or 240 mg/m² every 3 weeks.
Treatment was continued until disease progression.
Irinotecan has not been properly evaluated for its activity in breast
cancer. Dr. Perez said that, to her knowledge, this study provides the first
data by a North American cooperative group on a topoisomerase inhibitor in
"The response rates were very interesting, especially in patients
who had received both anthracyclines and taxanes. In the every-3-week arm,
we achieved a respectable 13% response rate, and in the other arm, 27%. So
we could speculate that if we have this high of a response rate after
anthracyclines and taxanes, it could be a lot higher in earlier stage breast
cancer," she said.
Median time to progression was comparable to that seen with other single
agents, which is about 3 to 4 months (see table below), Dr. Perez said.
Treatment produced an acceptable level of toxicity. Grade 3-4 neutropenia
occurred in 32% of patients treated weekly and in 36% of those treated every
3 weeks; diarrhea occurred in 17% and 12%; nausea in 6% and 16%; vomiting in
4% and 20%; and dyspnea in 14% and 18%, respectively.