Evaluation of the pharmacodynamic effects of MGCD0103 from preclinical models to human using a novel HDAC enzyme assay.
OBJECTIVE
The pharmacodynamic properties of MGCD0103, an isotype-selective inhibitor of histone deacetylase (HDAC), were evaluated in preclinical models and patients with a novel whole-cell HDAC enzyme assay.


METHODS
Boc-Lys(epsilon-Ac)-AMC, a HDAC substrate with fluorescent readout, was found to be cell permeable and was used to monitor MGCD0103-mediated HDAC inhibition in cultured cancer cells in vitro, in peripheral WBC ex vivo, in mice in vivo, and in human patients.


RESULTS
MGCD0103 inhibited HDAC activity in several human cancer cell lines in vitro and in human peripheral WBC ex vivo in a dose-dependent manner. Unlike suberoylanilide hydroxamic acid, the HDAC inhibitory activity of MGCD0103 was time dependent and sustained for at least 24 hours following drug removal in peripheral WBC ex vivo. Inhibitory activity of MGCD0103 was sustained for at least 8 hours in vivo in mice and 48 hours in patients with solid tumors. HDAC inhibitory activity of MGCD0103 in peripheral WBC correlated with induction of histone acetylation in blood and in implanted tumors in mice. In cancer patients, sustained pharmacodynamic effect of MGCD0103 was visualized only by dose-dependent enzyme inhibition in peripheral WBC but not by histone acetylation analysis.


CONCLUSIONS
This study shows that MGCD0103 has sustained pharmacodynamic effects that can be monitored both in vitro and in vivo with a cell-based HDAC enzyme assay.
Bonfils
Claire
C
MethylGene, Inc., Montreal, Quebec, Canada.
Kalita
Ann
A
Dubay
Marja
M
Siu
Lillian L
LL
Carducci
Michael A
MA
Reid
Gregory
G
Martell
Robert E
RE
Besterman
Jeffrey M
JM
Li
Zuomei
Z
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D001549:Benzamides / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D001681:Biological Assay / Q000379:methods*; D045744:Cell Line, Tumor; D004334:Drug Administration Schedule; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000032:analysis* / Q000187:drug effects; D006801:Humans; D020128:Inhibitory Concentration 50; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy*; D011743:Pyrimidines / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D001549:Benzamides; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D011743:Pyrimidines; C523184:mocetinostat; D006655:Histone Deacetylases