Diethylnitrosamine initiation does not alter clofibric acid-induced hepatocarcinogenesis in the rat.

Clofibric acid (CLO) is a nongenotoxic hepatocarcinogen in rodents that causes altered hepatocellular foci and/or neoplasms. Initiation by DNA-damaging agents such as diethylnitrosamine (DEN) accelerates focus and tumor appearance and could therefore significantly contribute to shortening of the regulatory 2-year rodent carcinogenicity bioassays. However, it is crucial to evaluate the histological and molecular impact of initiation with DEN on hepatocarcinogenesis promoted by CLO. Male F344 rats were given a single nonnecrogenic injection of DEN (0 or 30 mg/kg) followed by Control diet or CLO (5000 ppm) in diet for up to 20 months. Histopathology and gene expression profiling were performed in liver tumors and surrounding nontumoral liver tissues. The molecular signature of DEN was characterized and its histopathological and immunohistopathological effects on focus and tumor types were also determined. Although foci and tumors appeared earlier in the DEN+CLO-treated group compared to the group treated with CLO alone, DEN had little impact on gene expression in nontumoral tissues since the gene expression profiles were highly similar between Control and DEN-treated rats, and DEN+CLO- and CLO-treated rats. Finally, tumors obtained from DEN+CLO and CLO-treated groups displayed highly correlated gene expression profiles (r>0.83, independently of the time-point). The pathways involved in tumor development revealed by Gene Ontology functional analysis are similar when driven either by spontaneous initiation or by a chemically induced initiation step. Our work described here may contribute to the design optimization of shorter preclinical tests for the evaluation of the nongenotoxic hepatocarcinogenic potential of drugs under development.

Clinical outcomes in ER+ HER2 -node-positive breast cancer patients who were treated according to the Recurrence Score results: evidence from a large prospectively designed registry.

The Recurrence Score® is increasingly used in node-positive ER+ HER2-negative breast cancer. This retrospective analysis of a prospectively designed registry evaluated treatments/outcomes in node-positive breast cancer patients who were Recurrence Score-tested through Clalit Health Services from 1/2006 through 12/2011 (N = 709). Medical records were reviewed to verify treatments/recurrences/survival. Median follow-up, 5.9 years; median age, 62 years; 53.9% grade 2; 69.8% tumors ≤ 2 cm; 84.5% invasive ductal carcinoma; 42.0% N1mi, and 37.2%/15.5%/5.2% with 1/2/3 positive nodes; 53.4% Recurrence Score < 18, 36.4% Recurrence Score 18-30, and 10.2% Recurrence Score ≥ 31. Overall, 26.9% received adjuvant chemotherapy: 7.1%, 39.5%, and 86.1% in the Recurrence Score < 18, 18-30, and ≥ 31 group, respectively. The 5-year Kaplan-Meier estimates for distant recurrence were 3.2%, 6.3%, and 16.9% for these respective groups and the corresponding 5-year breast cancer death estimates were 0.5%, 3.4%, and 5.7%. In Recurrence Score < 18 patients, 5-year distant-recurrence rates for N1mi/1 positive node/2-3 positive nodes were 1.2%/4.4%/5.4%. As patients were not randomized to treatment and treatment decision is heavily influenced by Recurrence Score, analysis of 5-year distant recurrence by chemotherapy use was exploratory and should be interpreted cautiously: In Recurrence Score < 18, recurrence rate was 7.7% in chemotherapy-treated (n = 27) and 2.9% in chemotherapy-untreated patients (n = 352); P = 0.245. In Recurrence Score 18-30, recurrence rate in chemotherapy-treated patients (n = 102) was significantly lower than in untreated patients (n = 156) (1.0% vs. 9.7% P = 0.019); in Recurrence Score ≤ 25 (the RxPONDER study cutoff), recurrence rate was 2.3% in chemotherapy-treated (n = 89) and 4.4% in chemotherapy-untreated patients (n = 488); P = 0.521. In conclusion, our findings support using endocrine therapy alone in ER+ HER2-negative breast cancer patients with micrometastases/1-3 positive nodes and Recurrence Score < 18.

Clinical outcomes in patients with node-negative breast cancer treated based on the recurrence score results: evidence from a large prospectively designed registry.

The 21-gene Recurrence Score® (RS) assay is a validated prognostic/predictive tool in ER + early-stage breast cancer. However, clinical outcome data from prospective studies in RS ≥ 11 patients are lacking, as are relevant real-life clinical practice data. In this retrospective analysis of a prospectively designed registry, we evaluated treatments/clinical outcomes in patients undergoing RS-testing through Clalit Health Services. The analysis included N0 ER + HER2-negative breast cancer patients who were RS-tested from 1/2006 through 12/2010. Medical records were reviewed to verify treatments/recurrences/survival. The cohort included 1801 patients (median follow-up, 6.2 years). Median age was 60 years, 50.4% were grade 2 and 81.1% had invasive ductal carcinoma; 48.9% had RS < 18, 40.7% RS 18-30, and 10.4% RS ≥ 31, with chemotherapy use of 1.4, 23.7, and 87.2%, respectively. The 5-year Kaplan-Meier estimates for distant recurrence were 0.8, 3.0, and 8.6%, for patients with RS < 18, RS 18-30 and RS ≥ 31, respectively; the corresponding 5-year Kaplan-Meier estimates for breast cancer death were 0.0, 0.9, and 6.2%. Chemotherapy-untreated patients with RS < 11 (n = 304) and 11-25 (n = 1037) (TAILORx categorization) had 5-year Kaplan-Meier estimates for distant recurrence risk/breast cancer death of 1.0%/0.0% and 1.3%/0.4%, respectively. Our results extend those of the prospective TAILORx trial: the 5-year Kaplan-Meier estimates for distant recurrence and breast cancer death rate for the RS < 18 patients were very low supporting the use of endocrine therapy alone. Furthermore, in chemotherapy-untreated patients with RS 11-25 (where TAILORx patients were randomized to chemoendocrine or endocrine therapy alone), 5-year distant recurrence rates were also very low, suggesting that chemotherapy would not have conferred clinically meaningful benefit.

Characterization of an acute molecular marker of nongenotoxic rodent hepatocarcinogenesis by gene expression profiling in a long term clofibric acid study.

Evaluation of the nongenotoxic potential early during the development of a drug presents a major challenge. Recently, two genes were identified as potential molecular markers of rodent hepatic carcinogenesis: transforming growth factor-beta stimulated clone 22 (TSC-22) and NAD(P)H cytochrome P450 oxidoreductase (CYP-R) (1). They were identified after comparing the gene expression profiles obtained from the livers of Sprague-Dawley rats treated with different genotoxic and nongenotoxic compounds in a 5 day repeat dose in vivo study. To assess the potential of these two genes as acute markers of carcinogenesis, we investigated their modulation during a long-term nongenotoxic study in the rat using a classic initiation-promotion regime. Clofibric acid (CLO), which belongs to the broad class of chemicals known as peroxisome proliferators, was used as a nongenotoxic hepatocarcinogen. Male F344 rats were given a single nonnecrogenic injection of diethylnitrosamine (0 or 30 mg/kg) and fed a diet containing none or 5000 ppm CLO for up to 20 months. Necropsies of five rats per groups were performed at 18, 46, 102, 264, 377, 447 (control, DEN, and DEN + CLO rats), 524, and 608 days (for the CLO and control rats). Gross macroscopic and microscopic evaluation and gene expression profiling (on Affymetrix microarrays) were performed in peritumoral and tumoral liver tissues. Bioanalysis of the liver gene expression data revealed that TSC-22 was strongly down-regulated early in the study. Its underexpression was maintained throughout the study but disappeared upon CLO withdrawal. These modulations were confirmed by real-time polymerase chain reaction. However, CYP-R gene expression was not significantly altered in our study. Taken together, our results showed that TSC-22, but not CYP-R, has the potential to be an acute early molecular marker for nongenotoxic hepatocarcinogenesis in rodents.