BOSTONInterim results from an ongoing multicenter study suggest
that an irinotecan (Camptosar) dosing regimen of every 3 weeks for
patients with 5-fluorouracil (5-FU)-refractory colorectal cancer may
be associated with a lower incidence of grade 3-4 late diarrhea when
compared to a four-times-a-week schedule. The results were presented
at the 36th ASCO Annual Meeting.
What we intend to do is compare the two most commonly used
schedules for using this drug, Charles S. Fuchs, MD, study
author, told ONI. The first order of business is to see
whether there are any differences in efficacy between the two
schedules. We dont have any data on that yet.
In addition, we want to see what differences there are in
toxicity and quality of life, said Dr. Fuchs, of the
Dana-Farber Cancer Institute and Harvard Medical School.
This study, which is still accruing patients, will directly compare
two regimens of irinotecan in a total of 300 patients with 5-FU-refractory
colorectal cancer. These regimens are commonly used in the United
States for second-line therapy of colorectal cancer after first-line
Regimen A delivers irinotecan at 125 mg/m² four times a week for
6 weeks. In regimen B, patients receive 350 mg/m² every 3 weeks.
Patients 70 years of age or older, with a performance status of 2, or
with prior pelvic irradiation, receive 300 mg/m².
Patients were given supportive care, which included standard
antiemetics, atropine for cholinergic symptoms, and loperamide for
Results of the study to date include data on 40 patients in arm A and
82 patients in arm B.
Patient characteristics in both arms are comparable and include a
median age of 65 in arm A and 63 years in arm B, with 33% in arm A
and 26% in arm B being 70 or older. Sixty percent of patients in arm
A are male, compared with 56% in arm B. For arm B, starting doses of
350 mg/m² were given in 56% of this group, and 46% received 300 mg/m².
Clinically relevant grade 3-4 adverse events in the first 6 weeks of
therapy for patients in cycle 1 of arm A vs cycles 1 and 2 of arm B
are shown in the Table.
Additionally, moderate-to-severe cholinergic symptoms occurred in
2.5% of arm A patients vs 28% of arm B patients.
Final analyses, which may occur as early as summer 2000, will
directly compare 1-year survival, time to tumor progression, response
rate, safety, and quality of life among all 300 patients.