A phase I, pharmacokinetic and pharmacodynamic study on vorinostat in combination with 5-fluorouracil, leucovorin, and oxaliplatin in patients with refractory colorectal cancer.
OBJECTIVE
We conducted a phase I study to determine the maximum tolerated dose of vorinostat in combination with fixed doses of 5-fluorouracil (FU), leucovorin, and oxaliplatin (FOLFOX).


METHODS
Vorinostat was given orally twice daily for 1 week every 2 weeks. FOLFOX was given on days 4 and 5 of vorinostat. The vorinostat starting dose was 100 mg twice daily. Escalation occurred in cohorts of three to six patients. Pharmacokinetics of vorinostat, FU, and oxaliplatin were studied.


RESULTS
Twenty-one patients were enrolled. Thrombocytopenia, neutropenia, gastrointestinal toxicities, and fatigue increased in frequency and severity at higher dose levels of vorinostat. Two of 4 evaluable patients at dose level 4 (vorinostat 400 mg orally twice daily) developed dose-limiting fatigue. One of 10 evaluable patients at dose level 3 (vorinostat 300 mg orally twice daily) had dose-limiting fatigue, anorexia, and dehydration. There were significant relationships between vorinostat dose and the area under the curve on days 1 and 5 (Pearson, < 0.001). The vorinostat area under the curve increased (P = 0.005) and clearance decreased (P = 0.003) on day 5 compared with day 1. The median C(max) of FU at each dose level increased significantly with increasing doses of vorinostat, suggesting a pharmacokinetic interaction between FU and vorinostat. Vorinostat-induced thymidylate synthase (TS) modulation was not consistent; only two of six patients had a decrease in intratumoral TS expression by reverse transcription-PCR.


CONCLUSIONS
The maximum tolerated dose of vorinostat in combination with FOLFOX is 300 mg orally twice daily x 1 week every 2 weeks. Alternative vorinostat dosing schedules may be needed for optimal down-regulation of TS expression.
Fakih
Marwan G
MG
Department of Medicine, Pharmacology, and Radiology, Roswell Park Cancer Institute, Buffalo, NY, USA. marwan.fakih@roswellpark.org
Pendyala
Lakshmi
L
Fetterly
Gerald
G
Toth
Karoli
K
Zwiebel
James A
JA
Espinoza-Delgado
Igor
I
Litwin
Alan
A
Rustum
Youcef M
YM
Ross
Mary Ellen
ME
Holleran
Julianne L
JL
Egorin
Merrill J
MJ
D000230:Adenocarcinoma / Q000188:drug therapy* / Q000556:secondary; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000493:pharmacokinetics* / Q000494:pharmacology*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D006877:Hydroxamic Acids / Q000008:administration & dosage; D002955:Leucovorin / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009944:Organoplatinum Compounds / Q000008:administration & dosage; D000077150:Oxaliplatin; D011379:Prognosis; D015996:Survival Rate; D014018:Tissue Distribution; D016896:Treatment Outcome; D000077337:Vorinostat
D006877:Hydroxamic Acids; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D000077337:Vorinostat; D002955:Leucovorin; D005472:Fluorouracil