Expression of Transketolase like gene 1 (TKTL1) predicts disease-free survival in patients with locally advanced rectal cancer receiving neoadjuvant chemoradiotherapy.

BACKGROUND: For patients with locally advanced rectal cancer (LARC) neoadjuvant chemoradiotherapy is recommended as standard therapy. So far, no predictive or prognostic molecular factors for patients undergoing multimodal treatment are established. Increased angiogenesis and altered tumour metabolism as adaption to hypoxic conditions in cancers play an important role in tumour progression and metastasis. Enhanced expression of Vascular-endothelial-growth-factor-receptor (VEGF-R) and Transketolase-like-1 (TKTL1) are related to hypoxic conditions in tumours. In search for potential prognostic molecular markers we investigated the expression of VEGFR-1, VEGFR-2 and TKTL1 in patients with LARC treated with neoadjuvant chemoradiotherapy and cetuximab. METHODS: Tumour and corresponding normal tissue from pre-therapeutic biopsies of 33 patients (m: 23, f: 10; median age: 61 years) with LARC treated in phase-I and II trials with neoadjuvant chemoradiotherapy (cetuximab, irinotecan, capecitabine in combination with radiotherapy) were analysed by quantitative PCR. RESULTS: Significantly higher expression of VEGFR-1/2 was found in tumour tissue in pre-treatment biopsies as well as in resected specimen after neoadjuvant chemoradiotherapy compared to corresponding normal tissue. High TKTL1 expression significantly correlated with disease free survival. None of the markers had influence on early response parameters such as tumour regression grading. There was no correlation of gene expression between the investigated markers. CONCLUSION: High TKTL-1 expression correlates with poor prognosis in terms of 3 year disease-free survival in patients with LARC treated with intensified neoadjuvant chemoradiotherapy and may therefore serve as a molecular prognostic marker which should be further evaluated in randomised clinical trials.

KRAS and BRAF mutations and PTEN expression do not predict efficacy of cetuximab-based chemoradiotherapy in locally advanced rectal cancer.

PURPOSE: Mutations in KRAS and BRAF genes as well as the loss of expression of phosphatase and tensin homolog (PTEN) (deleted on chromosome 10) are associated with impaired activity of antibodies directed against epidermal growth factor receptor in patients with metastatic colorectal cancer. The predictive and prognostic value of the KRAS and BRAF point mutations as well as PTEN expression in patients with locally advanced rectal cancer (LARC) treated with cetuximab-based neoadjuvant chemoradiotherapy is unknown. METHODS AND MATERIALS: We have conducted phase I and II trials of the combination of weekly administration of cetuximab and irinotecan and daily doses of capecitabine in conjunction with radiotherapy (45 Gy plus 5.4 Gy) in patients with LARC (stage uT3/4 or uN+). The status of KRAS and BRAF mutations was determined with direct sequencing, and PTEN expression status was determined with immunohistochemistry testing of diagnostic tumor biopsies. Tumor regression was evaluated by using standardized regression grading, and disease-free survival (DFS) was calculated according to the Kaplan-Meier method. RESULTS: A total of 57 patients were available for analyses. A total of 31.6% of patients carried mutations in the KRAS genes. No BRAF mutations were found, while the loss of PTEN expression was observed in 9.6% of patients. Six patients achieved complete remission, and the 3-year DFS rate was 73%. No correlation was seen between tumor regression or DFS rate and a single marker or a combination of all markers. CONCLUSIONS: In the present series, no BRAF mutation was detected. The presence of KRAS mutations and loss of PTEN expression were not associated with impaired response to cetuximab-based chemoradiotherapy and 3-year DFS.

Annexin and survivin in locally advanced rectal cancer: indicators of resistance to preoperative chemoradiotherapy?

BACKGROUND: The aim of preoperative chemoradiotherapy is improvement of local control in patients with locally advanced rectal cancer (LARC). Recent studies have shown that annexin and survivin are involved in the resistance capability of tumours. We sought to determine whether survivin, annexin A4 or annexin A5 expression predict resistance to preoperative chemoradiotherapy. MATERIAL AND METHODS: Biopsies of tumour and normal rectal tissue were taken from 38 patients with LARC (cT3/4Nx or Tx/N+) before the start of chemoradiotherapy and during surgery. mRNA expression of annexin A4/A5 and survivin was measured by real-time polymerase chain reaction (RT-PCR) and correlated with down-staging and progression-free survival (PFS). RESULTS: Significantly higher mRNA levels of survivin, and annexin A4/A5 were detected in untreated tumour compared with normal mucosa. After chemoradiotherapy, this difference disappeared for survivin and annexin A4. Annexin A5 expression in the tumour increased during chemoradiotherapy. No correlation between the mRNA levels of survivin, annexin A4/A5 and tumour down-staging or PFS was noticed. CONCLUSIONS: In the present analysis of 38 patients with LARC undergoing neoadjuvant chemoradiotherapy, the expression levels of survivin and annexin A4 and A5 did not correlate with down-staging. Moreover, with regard to PFS, none of these markers was found to be prognostically relevant.