Gerner, Eugene W.

Abstract A61 Background Patients with Barrett's esophagus (BE) and dysplasia are ideal candidates for chemopreventive strategies to reduce cancer risk. Difluoromethylornithine (DMFO) is a promising chemopreventive agent that inhibits polyamine synthesis involved in the regulation of cell growth and differentiation. We conducted a pilot study to examine the effects of DFMO on esophageal histopathology, mucosal polyamine content, and gene expression. Materials and Methods Patients (n=10) with histologically confirmed BE and low grade dysplasia were enrolled in a single-arm study of DFMO (0.5 g/m2/d) given continuously for 6 months. Esophagoscopy with biopsies (4 quadrants every 1 cm) was performed at baseline, 3 and 6 months, and at 12 months (where available). Grading of dysplasia was performed by a GI pathologist blinded to clinical/biomarker data. Audiology was also performed. Mucosal polyamine content was measured by high-performance liquid chromatography, and analyzed using paired t-tests. Gene expression profiling was performed using a cDNA two-color chip, and was compared between baseline and 6 months. Expression data was normalized using the two-channel fastlo routine and differential expression was computed using a Wilcoxon signed-rank test. Results After 6 months of DFMO treatment, histopathological response data demonstrate regression of dysplasia (n= 1), stable disease (n= 8), and progression of dysplasia (n= 1). Within the stable category, 2 patients with extensive low grade dysplasia showed only focal dysplasia based upon 4 or more biopsies at 6 months. Histolopathological improvements seen at 6 months were maintained at 12 months. Overall, DFMO was well tolerated. One patient had subclinical, unilateral ototoxicity. Modulation of polyamines (spermine, spermidine, putrescine, histamine) was shown only for putrescine which decreased with treatment (6 mo., p=0.07) and showed recovery to baseline at 12 months (p= 0.01). Gene expression profiling revealed modulated genes of potential biological importance (KLF5, KAL1, RFC5, TIMM8a, TC10) and of these, Krüppel-like factor 5 (KLF5) was downregulated whereas the others were upregulated. Conclusion >Further study of the chemopreventive effect of DFMO upon BE with dysplasia is suggested. DFMO treatment suppressed mucosal putrescine levels and downregulated KLF5, an important mediator of cell proliferation. Citation Information: Cancer Prev Res 2008;1(7 Suppl):A61.

Abstract Patients with Barrett's esophagus (BE) and dysplasia are candidates for chemopreventive strategies to reduce cancer risk. We determined the effects of difluoromethylornithine (DMFO) on mucosal polyamines, gene expression, and histopathology in BE. Ten patients with BE and low-grade dysplasia participated in a single-arm study of DFMO (0.5 g/m2/d) given continuously for 6 months. Esophagoscopy with biopsies was conducted at baseline, 3, 6, and 12 months. Dysplasia was graded by a gastrointestinal pathologist. Audiology was assessed (at baseline and at 6 months). Mucosal polyamines were measured by high-performance liquid chromatography. Microarray-based gene expression was analyzed using a cDNA two-color chip. DFMO suppressed levels of the polyamines putrescine (P = 0.02) and spermidine (P = 0.02) and the spermidine/spermine ratio (P < 0.01) in dysplastic BE (6 months vs. baseline) that persisted at 6 months following drug cessation. Among the top 25 modulated genes, we found those regulating p53-mediated cell signaling (RPL11), cell-cycle regulation (cyclin E2), and cell adhesion and invasion (Plexin1). DFMO downregulated Krüppel-like factor 5 (KLF5), a transcription factor promoting cell proliferation, and suppressed RFC5 whose protein interacts with proliferating cell nuclear antigen. Histopathology showed regression of dysplasia (n = 1), stable disease (n = 8), and progression to high-grade dysplasia (n = 1). Polyamines were suppressed in the responder to a greater extent than in stable cases. DFMO was well tolerated, and one patient had subclinical, unilateral ototoxicity. DFMO suppressed mucosal polyamines and modulated genes that may be mechanistically related to its chemopreventive effect. Further study of DFMO for the chemoprevention of esophageal cancer in BE patients is warranted. Cancer Prev Res; 4(6); 829–39. ©2011 AACR.