Decitabine effect on tumor global DNA methylation and other parameters in a phase I trial in refractory solid tumors and lymphomas.
OBJECTIVE
By hypomethylating genes, decitabine may up-regulate factors required for chemotherapeutic cytotoxicity. Platinum-resistant cells may have reduced expression of the copper/platinum transporter CTR1.


METHODS
Thirty-one patients with refractory malignancies received decitabine 2.5 to 10 mg/m(2) on days 1 to 5, and 8 to 12 or 15 to 20 mg/m(2) on days 1 to 5. Tumor was assessed for DNA methylation (by LINE assays), apoptosis, necrosis, mitoses, Ki67, DNA methyltransferase (DNMT1), CTR1, and p16.


RESULTS
Febrile neutropenia was dose limiting. One thymoma patient responded. Decitabine decreased tumor DNA methylation (from median 51.2% predecitabine to 43.7% postdecitabine; P = 0.01, with effects at all doses) and in peripheral blood mononuclear cells (from 65.3-56.0%). There was no correlation between tumor and peripheral blood mononuclear cells. Patients starting decitabine < or =3 versus >3 months after last prior cytotoxic or targeted therapy had lower predecitabine tumor CTR1 scores (P = 0.02), higher p16 (P = 0.04), and trends (P = 0.07) toward higher tumor methylation and apoptosis. Decitabine decreased tumor DNMT1 for scores initially >0 (P = 0.04). Decitabine increased tumor apoptosis (P < 0.05), mitoses (if initially low, P = 0.02), and CTR1 (if initially low, P = 0.025, or if < or =3 months from last prior therapy, P = 0.04). Tumor CTR1 scores correlated inversely with methylation (r = -0.41, P = 0.005), but CTR1 promoter was not hypermethylated. Only three patients had tumor p16 promoter hypermethylation. P16 scores did not increase. Higher blood pressure correlated with lower tumor necrosis (P = 0.03) and a trend toward greater DNA demethylation (P = 0.10).


CONCLUSIONS
Exposure to various cytotoxic and targeted agents might generate broad pleiotropic resistance by reducing CTR1 and other transporters. Decitabine decreases DNA methylation and augments CTR1 expression through methylation-independent mechanisms.
Stewart
David J
DJ
M. D. Anderson Cancer Center, Houston, Texas, USA. dstewart@mdanderson.org
Issa
Jean-Pierre
JP
Kurzrock
Razelle
R
Nunez
Maria I
MI
Jelinek
Jaroslav
J
Hong
David
D
Oki
Yasuhiro
Y
Guo
Zhong
Z
Gupta
Sanjay
S
Wistuba
Ignacio I
II
D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D027682:Cation Transport Proteins / Q000378:metabolism; D000079923:Copper Transporter 1; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D000077209:Decitabine; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D020287:In Situ Nick-End Labeling; D019394:Ki-67 Antigen / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008223:Lymphoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D012737:Sex Factors; D016896:Treatment Outcome; D055815:Young Adult
D000964:Antimetabolites, Antineoplastic; D027682:Cation Transport Proteins; D000079923:Copper Transporter 1; D019394:Ki-67 Antigen; C490079:SLC31A1 protein, human; D000077209:Decitabine; D015254:DNA Modification Methylases; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D001374:Azacitidine