Phase I clinical and pharmacokinetic study of irinotecan, fluorouracil, and leucovorin in patients with advanced solid tumors.
OBJECTIVE
To determine the maximum-tolerable dose (MTD) of fluorouracil (5FU) when given with fixed doses of leucovorin and irinotecan (CPT-11), to define the dose-limiting toxicities of this combination, and to evaluate the effect of 5FU on the pharmacokinetics of CPT-11.


METHODS
CPT-11, leucovorin, and 5FU were administered in repeated 6-week cycles that consisted of weekly treatment with all three drugs for 4 consecutive weeks followed by a 2-week break. On day 1 of treatment, CPT-11 alone was given by 90-minute infusion, and pharmacokinetic sampling was performed over 24 hours. Leucovorin and 5FU were administered by brief intravenous injection on day 2. On days 8, 15, and 22, CPT-11 infusion was immediately followed by leucovorin and then 5FU. A second 24-hour pharmacokinetic sampling was performed on day 8, which permitted comparison of the pharmacokinetics of CPT-11 with and without 5FU. For the second 6-week cycle, leucovorin was administered first, followed by 5FU and then CPT-11, and a third pharmacokinetic sampling was performed.


RESULTS
Forty-two patients were entered onto this trial. The CPT-11 dose was initially fixed at 100 mg/m2. Leucovorin was fixed at 20 mg/m2. 5FU doses of 210, 265, 340, 425, and 500 mg/m2 were studied. When the 500-mg/m2 dose of 5FU was found to be tolerable, this was then maintained and CPT-11 was escalated to 125 and then 150 mg/m2. This final CPT-11 dose exceeded the MTD. Neutropenia was the major dose-limiting toxicity. Diarrhea was common, but was rarely dose-limiting. Coadministration of 5FU had no substantial effect on the pharmacokinetics of CPT-11 or SN-38. Among the 38 patients with colorectal cancer, six partial responses (PRs) were seen in this predominantly 5FU-refractory patient population.


CONCLUSIONS
5FU does not substantially affect the metabolism of CPT-11 to its active metabolite, SN-38. The combination of CPT-11125 mg/m2, 5FU 500 mg/m2, and leucovorin 20 mg/m2 is feasible and tolerable on this schedule.
Saltz
L B
LB
Gastrointestinal Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. SALTZL@MSKCC.ORG
Kanowitz
J
J
Kemeny
N E
NE
Schaaf
L
L
Spriggs
D
D
Staton
B A
BA
Berkery
R
R
Steger
C
C
Eng
M
M
Dietz
A
A
Locker
P
P
Kelsen
D P
DP
D000328:Adult; D000368:Aged; D000931:Antidotes / Q000008:administration & dosage; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects / Q000627:therapeutic use*; D002166:Camptothecin / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D003967:Diarrhea / Q000139:chemically induced; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D006801:Humans; D000077146:Irinotecan; D002955:Leucovorin / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy*
D000931:Antidotes; D000972:Antineoplastic Agents, Phytogenic; D000077146:Irinotecan; D002955:Leucovorin; D005472:Fluorouracil; D002166:Camptothecin