6115 VEGF gene polymorphisms in the prediction of benefit from first-line FOLFIRI plus bevacizumab (BV) in metastatic colorectal cancer (mCRC) patients (pts)

Pharmacodynamic and pharmacogenetic angiogenesis-related markers of first-line FOLFOXIRI plus bevacizumab schedule in metastatic colorectal cancer

Background:

The identification of molecular and genetic markers to predict or monitor the efficacy of bevacizumab (BV) represents a key issue in the treatment of metastatic colorectal cancer (mCRC).

Methods:

Plasma levels of vascular endothelial growth factor (VEGF), placental growth factor (PlGF), soluble VEGF receptor 2 (sVEGFR-2) and thrombospondin-1 (TSP-1) were assessed by ELISA assay at different time points in a cohort of 25 patients enroled in a phase II trial of GONO-FOLFOXIRI plus BV as first-line treatment of mCRC. VEGF: −2578A/C, −1498C/T, −1154A/G, −634C/G and 936C/T; and VEGFR-2: −604A/G, +1192C/T and +1719A/T, polymorphisms were assessed in a total of 54 patients.

Results:

Treatment with GONO-FOLFOXIRI plus BV determined a prolonged and significant reduction in plasma free, biologically active VEGF concentration. Interestingly, VEGF concentrations remained lower than at baseline also at the time of PD. Conversely, PlGF levels increased during the treatment if compared with baseline, suggesting a possible role in tumour resistance; moreover, sVEGFR-2 increased at the time of PD, as well as TSP-1. No association of assessed polymorphisms with outcome was found.

Conclusion:

Our study suggested the possible mechanisms of resistance to combined therapy in those patients with a progressive disease to be tested in ongoing phase III randomised studies.

Pharmacogenetic interaction analysis for the efficacy of systemic treatment in metastatic colorectal cancer

BACKGROUND

Pharmacogenetic markers related to drug metabolism and mechanisms of action could help to better select patients with metastatic colorectal cancer (mCRC) for treatment. Genetic interaction analysis is used as a rational tool to study the contribution of polygenic variation in relation to drug response.

PATIENTS AND METHODS

A selection of 17 polymorphisms in genes encoding drug targets, pathway molecules and detoxification enzymes was analyzed in 279 previously untreated mCRC patients treated with capecitabine, oxaliplatin and bevacizumab (CAPOX-B). Multifactor dimensionality reduction analysis was used to identify a genetic interaction profile for progression-free survival (PFS).

RESULTS

Median PFS was 10.9 [95% confidence interval (CI) 9.4-12.4] months. A genetic interaction profile consisting of the TYMS enhancer region and VEGF +405G>C polymorphisms was significantly associated with PFS. Median PFS was 13.3 (95% CI 11.4-15.3) and 9.7 (95% CI 7.6-11.8) months for the beneficial and unfavorable genetic profiles, respectively, corresponding to a hazards ratio for PFS of 1.58 (95% CI 1.14-2.19). None of the studied polymorphisms were individually associated with PFS.

CONCLUSIONS

Our results support a genetic interaction between the TYMS enhancer region and VEGF +405G>C polymorphisms as a predictor of the efficacy of CAPOX-B in mCRC patients.