DNA IMAGE CYTOMETRIC MEASUREMENT AS A SURROGATE END-POINT BIOMARKER IN A PHASE-I TRIAL OF ALPHA-DIFLUOROMETHYLORNITHINE FOR CERVICAL INTRAEPITHELIAL NEOPLASIA

Cervical intraepithelial neoplasia grade 3 (GIN 3) is considered a hig h-risk precursor of invasive cervical cancer. cu-Difluoromethylornithi ne (DFMO) is a promising antiproliferative chemopreventive agent, The purpose of this study was to evaluate image cytometric measurement of nuclear DNA (ICM-DNA) as a surrogate end point biomarker (SEE) in a Ph ase I trial of DFMO for GIN. Thirty patients with CIN 3 were treated w ith DFMO at five doses, ranging from 0.0625 to 1.0 g/m(2)/day, for 1 m onth, Half of the patients had histological responses. Twenty-five pre -and posttreatment cervical biopsy specimens (from 11 responders and 1 4 nonresponders) were available for this analysis, ICM-DNA was perform ed on 4-mu m sections cut from formalin-fixed tissue blocks and staine d with a thionin-SO2 Feulgen reaction, ICM-DNAs for each case were exp ressed as normalized measurements (against the nuclear modal absorbanc e of lymphocytes) of the absorbance of each cell of interest and were presented in bar histograms, The mean normalized summed absorbance (Si gma ODn) was obtained as a mean histogram of the cell population of in terest, Nineteen (76%) of 25 patients had a significant decrease in Si gma ODn after DFMO treatment, Posttreatment values were significantly lower than pretreatment values in a paired analysis, and responders ha d significantly lower values than nonresponders, Analyses of different ICM-DNA references, including percentile values of Sigma ODn distribu tion, DNA malignancy grade, and 5c exceeding rate, showed a decrease o f mean Sigma ODn during DFMO treatment, In addition, the summed posttr eatment Sigma ODn histograms also showed progressively shorter right s houlders compared with pretreatment histograms in both responders and nonresponders, We concluded that the modulation of Sigma ODn reflected the chemoprevention effect of DFMO even before morphological changes appeared, and thus, ICM-DNA may be useful as a SEE in chemoprevention trials of DFMO. Additional reasons for using ICM-DNA as a SEE are the relative simplicity of its use, the high accuracy of the results, the low cost of the reagents, the ability to use small tissue samples, and the objectivity and reproducibility of the procedure.