Alternative dosing schedules for irinotecan.
Most of the clinical experience with irinotecan (CPT-11 [Camptosar]) has been with either a weekly or an every-3-week schedule. Recent phase I trials have explored new routes and schedules of administration. One approach attempts to maximize dose frequency and intensity by giving irinotecan every 2 weeks. A phase I trial of this approach is now complete and has led to a phase II trial in patients with recurrent colorectal cancer. Data suggest that smaller doses of a topoisomerase I inhibitor administered repeatedly may result in greater antitumor activity than large doses administered intermittently. A phase I trial has been performed in adults in which irinotecan was administered daily for 5 consecutive days, followed by 2 days off, for 2 weeks out of 3. Similar trials are under way in children. Oral administration, another strategy that has undergone phase I testing, has several theoretical advantages:(1) The acidic pH of the stomach favors maintenance of irinotecan in the active lactone ring form. (2) Irinotecan is more rapidly and extensively converted to SN-38 by tissue carboxylesterases found in high concentrations in the gut and liver. (3) Low doses can be delivered over a protracted period. (4) The oral route enhances patient convenience. These alternative dosing schedules may facilitate integration of irinotecan into combination chemotherapy and combined-modality treatment regimens.
Rothenberg
M L
ML
Division of Medical Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Kuhn
J G
JG
Schaaf
L J
LJ
Drengler
R L
RL
Eckhardt
S G
SG
Villalona-Calero
M A
MA
Hammond
L
L
Miller
L L
LL
Petit
R G
RG
Rowinsky
E K
EK
Von Hoff
D D
DD
D000328:Adult; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006801:Humans; D000077146:Irinotecan
D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D002166:Camptothecin