A phase I dose-finding study of 5-azacytidine in combination with sodium phenylbutyrate in patients with refractory solid tumors.
OBJECTIVE
This was a phase I trial to determine the minimal effective dose and optimal dose schedule for 5-azacytidine (5-AC) in combination with sodium phenylbutyrate in patients with refractory solid tumors. The pharmacokinetics, pharmacodynamics, and antineoplastic effects were also studied.


METHODS
Three dosing regimens were studied in 27 patients with advanced solid tumors, and toxicity was recorded. The pharmacokinetics of the combination of drugs was evaluated. Repeat tumor biopsies and peripheral blood mononuclear cells (PBMC) were analyzed to evaluate epigenetic changes in response to therapy. EBV titers were evaluated as a surrogate measure for gene re-expression of epigenetic modulation in PBMC.


RESULTS
The three dose regimens of 5-AC and phenylbutyrate were generally well tolerated and safe. A total of 48 cycles was administrated to 27 patients. The most common toxicities were bone marrow suppression-related neutropenia and anemia, which were minor. The clinical response rate was disappointing for the combination of agents. One patient showed stable disease for 5 months whereas 26 patients showed progressive disease as the best tumor response. The administration of phenylbutyrate and 5-AC did not seem to alter the pharmacokinetics of either drug. Although there were individual cases of targeted DNA methyltransferase activity and histone H3/4 acetylation changes from paired biopsy or PBMC, no conclusive statement can be made based on these limited correlative studies.


CONCLUSIONS
The combination of 5-AC and phenylbutyrate across three dose schedules was generally well tolerated and safe, yet lacked any real evidence for clinical benefit.
Chemical Therapeutics Program, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Johns Hopkins University, Baltimore, Maryland 21231, USA.
Jianqing
J
Lin
Jill
J
Gilbert
Michelle A
MA
Rudek
James A
JA
Zwiebel
Steve
S
Gore
Anchalee
A
Jiemjit
Ming
M
Zhao
Sharyn D
SD
Baker
Richard F
RF
Ambinder
James G
JG
Herman
Ross C
RC
Donehower
Michael A
MA
Carducci
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D001374:Azacitidine / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005260:Female; D051548:Histone Acetyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D010654:Phenylbutyrates / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D016896:Treatment Outcome
D010654:Phenylbutyrates; C075773:4-phenylbutyric acid; D015254:DNA Modification Methylases; D051548:Histone Acetyltransferases; D001374:Azacitidine