Phase I and pharmacokinetic study of once daily oral administration of S-1 in patients with advanced cancer.
OBJECTIVE
To determine the maximum tolerated dose, dose-limiting toxicities(DLTs), and pharmacokinetics of S-1, a combination of tegafur, 5-chloro-2,4-dihydroxypyridine (CDHP), and oxonic acid, administered once daily in patients with advanced cancer.


METHODS
Eighteen patients with refractory malignancies were treated with S-1 administered once daily for 21 consecutive days, followed by a 1-week break. Of 16 evaluable patients, 6 were treated at a dose of 50 mg/m(2)/day, and 10 were treated at 60 mg/m(2)/day.


RESULTS
DLTs were observed in 1 of 6 evaluable patients treated with 50 mg/m(2)/day and in 4 of 10 evaluable patients treated with 60 mg/m(2)/day. DLTs included diarrhea, nausea/vomiting, fatigue, and hyperbilirubinemia. The maximum tolerated dose was 50 mg/m(2)/day. Pharmacokinetic data are consistent with potent modulation of 5-fluorouracil (5-FU) by CDHP, with prolonged half-life and 5-FU AUC at least 10-fold higher than reported in previous studies of equitoxic doses of tegafur modulated by uracil. Pharmacodynamic analysis demonstrated a correlation between diarrhea grade and both 5-FU C(max) (r = 0.57, P < 0.05) and 5-FU area under the curve (r = 0.74, P < 0.01).


CONCLUSIONS
The recommended Phase II dose of S-1 administered once daily for 21 consecutive days of 28 is 50 mg/m(2). The pharmacokinetic data presented provide evidence of 5-FU modulation by CDHP. Pharmacodynamic analyses suggest that the utility of pharmacology-based dosing of S-1 should be explored in future trials. Evaluation of once-daily dosing of S-1 in malignancies for which fluoropyrimidines have known antitumor activity is warranted.
Department of Medical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Steven J
SJ
Cohen
Cynthia G
CG
Leichman
Gwen
G
Yeslow
Mary
M
Beard
April
A
Proefrock
Brian
B
Roedig
Bharat
B
Damle
Stephen P
SP
Letrent
Arthur P
AP
DeCillis
Neal J
NJ
Meropol
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019540:Area Under Curve; D004334:Drug Administration Schedule; D004338:Drug Combinations; D005260:Female; D005767:Gastrointestinal Diseases / Q000139:chemically induced; D006801:Humans; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D010094:Oxonic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011725:Pyridines / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005641:Tegafur / Q000008:administration & dosage / Q000493:pharmacokinetics*
D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; D011725:Pyridines; C079198:S 1 (combination); D005641:Tegafur; D010094:Oxonic Acid