J. Yun

Molecular Determinants of Cetuximab Efficacy

PURPOSE To investigate whether mRNA expression levels of cyclin D1 (CCND1), cyclooxygenase 2 (Cox-2), epidermal growth factor receptor (EGFR), interleukin 8 (IL-8), and vascular endothelial growth factor (VEGF), all members of the EGFR signaling pathway, are associated with clinical outcome in patients with EGFR-expressing metastatic colorectal cancer (CRC) treated with cetuximab. PATIENTS AND METHODS Thirty-nine patients with metastatic CRC, refractory to both irinotecan and oxaliplatin, were enrolled on IMCL-0144 and treated with single-agent cetuximab. The intratumoral mRNA levels of CCND1, Cox-2, EGFR, IL-8, and VEGF were assessed from paraffin-embedded tissue samples using laser-capture microdissection and quantitative real-time polymerase chain reaction. RESULTS There were 21 women and 18 men with a median age of 64 years (range, 35 to 83 years). Higher gene expression levels of VEGF were associated with resistance to cetuximab (P = .038; Kruskal-Wallis test). The combination of low gene expression levels of Cox-2, EGFR, and IL-8 was significantly associated with overall survival (13.5 v 2.3 months; P = .028; log-rank test). Both findings were independent of skin toxicity that was itself significantly correlated to survival. Patients with a lower mRNA amount of EGFR had a longer overall survival compared with patients that had a higher mRNA amount (7.3 v 2.2 months; P = .09; log-rank test). Patients with lower expression of Cox-2 had a significantly higher rate of grade 2 to 3 skin reactions under cetuximab treatment. CONCLUSION This pilot study suggests that gene expression levels of Cox-2, EGFR, IL-8, and VEGF in patients with metastatic CRC may be useful markers of clinical outcome in single-agent cetuximab treatment.

Genomic profiling associated with recurrence in patients with rectal cancer treated with chemoradiation

PURPOSE Stage II and III adenocarcinoma of the rectum has an overall 5-year survival rate of approximately 50%, and tumor recurrence remains a major problem despite an improvement in local control through chemotherapy and radiation. The efficacy of chemoradiation therapy may be significantly compromised as a result of interindividual variations in clinical response and host toxicity. Therefore, it is imperative to identify those patients who will benefit from chemoradiation therapy and those who will develop recurrent disease. In this study, we tested whether a specific pattern of 21 polymorphisms in 18 genes involved in the critical pathways of cancer progression (i.e., drug metabolism, tumor microenvironment, cell cycle regulation, and DNA repair) will predict the risk of tumor recurrence in rectal cancer patients treated with chemoradiation. PATIENTS AND METHODS A total of 90 patients with Stage II or III rectal cancer treated with chemoradiation were genotyped using polymerase chain reaction (PCR)-based techniques for 21 polymorphisms. RESULTS A polymorphism in interleukin (IL)-8 was individually associated with risk of recurrence. Classification and regression tree analysis of all polymorphisms and clinical variables developed a risk tree including the following variables: node status, IL-8, intracellular adhesion molecule-1, transforming growth factor-beta, and fibroblast growth factor receptor 4. CONCLUSION Genomic profiling may help to identify patients who are at high risk for developing tumor recurrence, and those who are more likely to benefit from chemoradiation therapy. A larger prospective study is needed to validate these preliminary data using germline polymorphisms on tumor recurrences in rectal cancer patients treated with chemoradiation.

Association of Cyclin D1 (CCND1) gene A870G polymorphism and clinical outcome of EGFR-positive metastatic colorectal cancer patients treated with epidermal growth factor receptor (EGFR) inhibitor cetuximab (C225)

3518 Background Cetuximab (C225) is a chimeric anti-EGFR monoclonal antibody with efficacy against EGFR-positive metastatic colorectal cancer. Recently, the link between EGFR signaling and the cell cycle has been identified. In vitro studies show blockade of EGFR by C225 can induce cell cycle arrest in the G1 phase which mediated by inhibition of interactions between cyclins and CDKs and increases expression of the cell cycle inhibitor p27KIP1. A frequent A870G polymorphism in the final codon of exon 4 of the Cyclin D1, leads gene alternatively spliced to produce two different mRNA transcripts [a] and [b] was also identified. In vivo studies have indicated this polymorphism can affect the prognosis of patients with different types of solid tumors. We hypothesized that CCND1 A870G polymorphism will predict clinical outcome in EGFR-positive metastatic colorectal cancer patients treated with EGFR inhibitor Cetuximab(C225). Methods Cyclin D1 A870G gene polymorphism was tested using PCR-RFLP method in genomic DNA extracted from peripheral blood from 39 metastatic colorectal cancer patients enrolled in a phase II EGFR inhibitor Cetuximab(C225) clinical trial. ResultsWe found a significant association between A870G polymorphism and overall survival of patients treated with Cetuximab(C225). With median follow-up 8.7 months (range 2.5, 11.7) and median survival time 4.8 months (95%C.I 2.7, 8.5), Patients with AA homozygous genotype survived a median time of 2.3 months (95%C.I 2.1, 5.7) compared with those have homozygous GG genotype 4.4 months (95%C.I 1.8, 9.8+) or heterozygous AG genotype 8.5 months(95%C.I 5.5, 11.7+), respectively (p<0.05, logrank test). ConclusionsThese data suggest that Cyclin D1 A870G polymorphism may be a potential prognostic molecular marker for clinical outcome of the EGFR-positive metastatic colorectal caner patients treated with third line EGFR inhibitor Cetuximab (C225). Prospective studies are needed to confirm these preliminary findings. [Table: see text].

Polymorphisms in IL-8 and the GSTP1 are associated with survival of metastatic colorectal cancer patients treated with CPT-11

3606 Background Irinotecan (CPT-11), an analogue of Camptothecins, demonstrates a broad spectrum of antitumor activity. Currently, there are no prognostic molecular markers for CPT-11 efficacy. Therefore, we investigated associations between polymorphisms in genes involved in CPT-11 metabolism (UGT1A1), chemoresistance (GSTP1), DNA repair (XPD, ERCC1, XRCC1, Werner 1074, and Werner 1367), and angiogenesis (IL-8 and COX-2) and survival of patients with metastatic colorectal cancer receiving CPT-11 based chemotherapy. In vivo studies show GSTP1 to detoxify chemotherapeutic agents by glutathione conjugation. In vivo and in vitro studies show IL-8 to possess angiogenic properties and its overexpression is associated with metastasis potential in colorectal cancer. Positional cloning studies identified Werner as the gene responsible for Werner Syndrome (WS), and cells from these patients have been shown to be particularly sensitive to Camptothecin. Methods The gene polymorphisms were tested using PCR-RFLP method on genomic DNA extracted from peripheral blood from metastatic colorectal cancer patients treated with CPT-11. Results 55 patients were collected; 31 males and 24 females; median age 55 (range 34-77) years. The response to CPT-11 was 40% (18/45, 1 pt was inevaluable, and 9 pts are still receiving treatment and were too early to be evaluated), with median survival of 22.9 (95% CI: 18.4, 29.3) months. The median time of follow-up and range was 15.4 (4.7-26.1) months. Individually, IL-8 and GSTP1 showed trends for overall survival (log rank p=0.07 and p=0.077, respectively). A combined analysis of these two genes showed patients carrying two favorable genotypes (homozygous Ile for GSTP1 and T allele for IL-8) had longer survival when compared with those patients carrying no favorable genotypes or only 1 favorable genotype (p=0.005). The Werner Loci polymorphisms also showed a trend for overall survival. Conclusion These data suggest that IL-8, GSTP1, and the Werner Loci polymorphisms may be potential prognostic molecular markers for clinical outcome of metastatic colorectal cancer patients treated with a CPT-11 regimen. [Table: see text].

Gene expression profiling associated with risk of recurrence in patients with colorectal cancer

3602 Background: Early identification of patients at increased risk for recurrence remains a central issue in the treatment of colorectal cancer. Altered expression levels in cancer-related genes h...