Novel biomarkers in primary breast core biopsies to predict poor response to neoadjuvant chemotherapy and appearance of metastases.

Drug resistance has been one of the major obstacles limiting the success of cancer chemotherapy. In two thirds of breast cancer patients, large (>1cm) residual tumors are present after neoadjuvant chemotherapy (NCT). The residual tumor and involved nodes have been indicators of relapse and survival very important in breast cancer. The goal of this preliminary study was to assess the predictive significance of a panel of molecular biomarkers, related with the response to treatment or drug resistance to NCT, as determined on the diagnostic tumor. The expression of 22 proteins was examined using immunohistochemistry in tissue microarrays (TMA) from 115 patients of stage II-III breast cancer, treated with NCT. Among studied proteins, there are some that are anti-apoptotic, pro-proliferative, cancer stem cell markers and the Vitamin D Receptor. Other proteins are involved in the identification of molecular subtype, cell cycle regulation or DNA repair. Next, a predictive signature of poor response was generated from independent markers of predictive value. Tumors that expressed four or five conditions (biomarkers of chemoresistance with a determinated cutoff) were associated with a 9-fold increase in the chances of these patients of having a poor response to NCT. Additionally, we also found a worse prognostic signature, generated from independent markers of prognostic value. Tumors which expressed two or three conditions of worst prognostic, were associated with a 6-fold reduction in Distant Disease Free Survival. In conclusion, finding biomarkers of chemoresitance (ypTNM II-III) and metastases can become a stepping stone for future studies that will need to be assessed in a bigger scale.

Tumor thymidylate synthase 1494del6 genotype as a prognostic factor in colorectal cancer patients receiving fluorouracil-based adjuvant treatment.

PURPOSE: The purpose of this study was to analyze the value of germline and tumor thymidylate synthase (TS) genotyping as a prognostic marker in a series of colorectal cancer patients receiving adjuvant fluorouracil (FU) -based treatment. PATIENTS AND METHODS: One hundred twenty-nine colorectal cancer patients homogeneously treated with FU plus levamisole or leucovorin in the adjuvant setting were included. TS enhancer region, 3R G > C single nucleotide polymorphism (SNP), and TS 1494del6 polymorphisms were assessed in both fresh-frozen normal mucosa and tumor. Mutational analyses of TS and allelic imbalances were studied in all primary tumors and in 18 additional metachronic metastases. TS protein immunostaining was assessed in an expanded series of 214 tumors. Multivariate Cox models were adjusted for stage, differentiation, and location. RESULTS: Tumor genotyping (frequency of allelic loss, 26%) showed that the 3R/3R genotype was associated with a better outcome (hazard ratio [HR] = 0.38; 95% CI, 0.16 to 0.93; P = .020 for the recessive model). 3R G > C SNP genotyping did not add prognostic information. Tumor TS 1494del6 allele (frequency of allelic loss, 36%) was protective (for each allele with the deletion, based on an additive model, HR = 0.42; 95% CI, 0.22 to 0.82; P = .0034). Both polymorphisms were in strong linkage disequilibrium (D' = 0.71, P < .001), and the 3R/-6 base pair (bp) haplotype showed a significant overall survival benefit compared with the most prevalent haplotype 2R/+6bp (HR = 0.42; 95% CI, 0.20 to 0.85; P = .017). No TS point mutation was detected in primary tumors or metastases. TS protein immunostaining was not associated with survival or any of the genotypes analyzed. CONCLUSION: Tumor TS 1494del6 genotype may be a prognostic factor in FU-based adjuvant treatment of colorectal cancer patients.