1617P - Clinical interest of digital PCR for routine detection of circulating DNA in metastatic colorectal cancer

Date 28 September 2014
Event ESMO 2014
Session Poster Display session
Topics Colon Cancer
Rectal Cancer
Translational Research
Presenter David Sefrioui
Citation Annals of Oncology (2014) 25 (suppl_4): iv546-iv563. 10.1093/annonc/mdu358
Authors D. Sefrioui1, C. Vasseur2, R. Sesboué2, F. Blanchard3, A. Gangloff1, M. Baretti4, L. Beaussire2, F. Clatot5, C. Dolfus3, J. Sabourin3, P. Michel1, T. Frebourg2, F. Di Fiore6
  • 1Digestive Oncology Unit, C.H.U. Charles Nicolle, FR-76000 - Rouen/FR
  • 2U1079, Rouen University, FR-76000 - Rouen/FR
  • 3Department Of Pathology, C.H.U. Charles Nicolle, FR-76000 - Rouen/FR
  • 4Cancer Center, Humanitas Clinical and Research Center, Rozzano/IT
  • 5Medical Oncology Department, Centre Henri Becquerel, 76000 - Rouen/FR
  • 6Digestive Oncology Unit, CHU Hôpitaux de Rouen-Charles Nicolle, 76031 - Rouen/FR

Abstract

Aim

Liquid biopsy based on circulating DNA is considered as a promising issue in cancer patients to assess key somatic alterations involved in disease progression or in treatment sensitivity. However, the clinical relevance of sensitive detection methods such as Digital PCR remains to be established. The aim was to evaluate the clinical interest of Digital PCR in circulating DNA detection including cell-free (cfDNA) and circulating tumour (ctDNA) DNA in patients treated for a metastatic colorectal cancer (MCRC).

Methods

A prospective single-center study was conducted from April to July 2013 in 34 patients treated for a MCRC. DNA was extracted from 1 mL of plasma using the QIAamp ® kit Circulating Nucleic Acid. ctDNA was detected and quantified (fragments per mL of plasma) by Digital PCR (Digital 3D ™ QuantStudio ®, Life Technologies) from KRAS mutations identified in the primary tumor. cfDNA was also quantified by Digital PCR and expressed in ng/mL of plasma. Response to chemotherapy and survival were analyzed according to both cfDNA and ctDNA. cfDNA was integrated as a dichotomized covariate (above versus below 75% percentile) for response and overall survival (OS) analysis.

Results

The mean cfDNA concentration was 106 ng/mL (range, 3-1443 ng/mL). KRAS mutations were identified in tumour from 16/34 patients (c.34G>T, n=1; c.35G>A, n=8; c.35G>C, n=3; c.35G>T, n=2; c.38G>A, n=2) with a sensitivity and specificity for ctDNA detection of 63% (10/16) and 100% (0/18), respectively. The mean level of ctDNA was 21972 fragments/mL (range, 136 and 308,000). There was a significant correlation between cfDNA and ctDNA (&rgr;=0.993, p<0.0001). Moreover, cfDNA and ctDNA were significantly associated with 3-months survival (respectively 51 vs 372 ng/mL, p=0.0048 and 1300 vs 108,000/ml, p=0.02). Using 75th percentile as cut-off, control disease and median OS were also significantly decreased in patients with high cfDNA as compared to those with low level (respectively 53% vs 89%, p=0.02 and 4.8 months vs not reached; p=0.02).

Conclusions

Digital PCR is a simple and non-invasive method allowing the routine detection of circulating DNA. Our results also highlight that cfDNA and ctDNA are correlate markers with a significant prognostic impact in MCRC patients.

Disclosure

All authors have declared no conflicts of interest.