Peter V. Danenberg

PURPOSE: Overexpression of the excision repair cross-complementing 1 (ERCC1) gene, which is crucial in the repair of cisplatin (CDDP)-DNA adducts, is reported to negatively influence the effectiveness of CDDP-based therapy for gastric and ovarian cancers. Recent evidence indicates that Gemcitabine (Gem) may modulate ERCC1 nucleotide excision repair activity, and down-regulation of DNA repair activity by ERCC1 antisense RNA reportedly inhibits synergism of CDDP/Gem. We investigated whether ERCC1 mRNA expression levels were associated with clinical outcomes after treatment with a combination Gem/CDDP regimen for patients with advanced stage non-small cell lung cancer (NSCLC). EXPERIMENTAL DESIGN: Response and survival were correlated with the level of ERCC1 expression in 56 patients with advanced (stage IIIb or IV) NSCLC treated as part of a multicenter randomized trial with Gem 1250 mg/m(2) days 1 and 8 plus CDDP 100 mg/m(2) on day 1 every 3 weeks. mRNA was isolated from paraffin-embedded pretreatment primary tumor specimens, and relative expression levels of ERCC1/beta-actin were measured using a quantitative reverse transcription-PCR (Taqman) system. RESULTS: ERCC1 expression was detectable in all tumors. There were no significant differences in ERCC1 levels by gender, age, performance status, weight loss, or tumor stage. The overall response rate was 44.7%. There were no significant associations between ERCC1 expression and response. Median overall survival was significantly longer in patients with low ERCC1 expression tumors (61.6 weeks; 95% confidence interval, 42.4-80.7 weeks) compared to patients with high expression tumors (20.4 weeks, 95% confidence interval, 6.9-33.9 weeks). ERCC1 expression, Eastern Cooperative Oncology Group performance status, and presence of weight loss were significant prognostic factors for survival in a Cox proportional hazards multivariable analysis. CONCLUSIONS: These data suggest that ERCC1 expression is a predictive factor for survival after CDDP/Gem therapy in advanced NSCLC. Although there was a trend toward decreased response with high ERCC1 mRNA levels, this difference failed to reach statistical significance. This result may reflect the impact of Gem and the requirement for ERCC1 expression for CDDP/Gem synergism or may be attributable to the relatively small patient sample size in this study. Prospective studies of ERCC1 as a predictive marker for activity of CDDP-based regimens in NSCLC are warranted.

PURPOSE: To test the hypotheses of whether the relative mRNA expression of the thymidylate synthase (TS) gene and the excision cross-complementing (ERCC1) gene are associated with response to and survival of fluorouracil (5-FU)/oxaliplatin chemotherapy in metastatic colorectal cancer. PATIENTS AND METHODS: Patients had progressive stage IV disease after unsuccessful 5-FU and irinotecan chemotherapy. All patients were evaluated for eligibility for a compassionate 5-FU/oxaliplatin protocol. cDNA was derived from paraffin-embedded tumor specimens to determine TS and ERCC1 mRNA expression relative to the internal reference gene beta-actin using fluorescence-based, real-time reverse transcriptase polymerase chain reaction. RESULTS: The median TS gene expression level from 50 metastasized tumors was 3.4 x 10(-3) (minimum expression, 0.18 x 10(-3);maximum expression, 11.5 x 10(-3)), and the median ERCC1 gene expression level was 2.53 x 10(-3) (minimum, 0.0; maximum, 14.61 x 10(-3)). The gene expression cutoff values for chemotherapy nonresponse were 7.5 x 10(-3) for TS and 4.9 x 10(-3) for ERCC1. The median survival time for patients with TS <or= 7.5 x 10(-3) (43 of 50 patients) was 10.2 months, compared with 1.5 months for patients with TS greater than 7.5 x 10(-3) (P < .001). Patients with ERCC1 expression <or= 4.9 x 10(-3) (40 of 50 patients) had a median survival time of 10.2 months, compared with 1.9 months for patients with ERCC1 expression greater than 4.9 x 10(-3) (P < .001). A TS of 7.5 x 10(-3) segregated significantly into response, stable disease, and progression (P = .02), whereas the association between ERCC1 and response did not reach statistical significance (P = .29). CONCLUSION: These data suggest that intratumoral ERCC1 mRNA and TS mRNA expression levels are independent predictive markers of survival for 5-FU and oxaliplatin combination chemotherapy in 5-FU-resistant metastatic colorectal cancer. Precise definition of the best TS cut point will require further analysis in a large, prospective study.

Effective development of targeted anticancer agents includes the definition of the optimal biological dose and biomarkers of drug activity. Currently available preclinical models are not optimal to this end. We aimed at generating a model for translational drug development using pancreatic cancer as a prototype. Resected pancreatic cancers from 14 patients were xenografted and expanded in successive groups of nude mice to develop cohorts of tumor-bearing mice suitable for drug therapy in simulated early clinical trials. The xenografted tumors maintain their fundamental genotypic features despite serial passages and recapitulate the genetic heterogeneity of pancreatic cancer. The in vivo platform is useful for integrating drug screening with biomarker discovery. Passages of tumors in successive cohorts of mice do not change their susceptibility to anticancer agents and represent a perpetual live bank, facilitating the application of new technologies that will result in the creation of an integrated stable database of tumor-drug response data and biomarkers.