Download the ESMO 2012 Abstract Book - Oxford Journals

Annals of Oncology
abstr.3608) We extended the study by examining PTEN, PIK exon 9 and 20 for
mutations and methylation and correlated all the genes to tumor stage. We divided
TNM into early stage I & II and late III & IV.
Method: Ethical approval was obtained. DNA was extracted from tumor samples
obtained from CRC patients by resection. The PTEN methylation was analyzed by
methylation-specific PCR. and analyzed by gel electrophoresis after Sybr green
staining and UV-photography.
Results: Data were available for 117 patients. Correlation coefficients were calculated
and their significance assessed using Chi-squared: RAS/BRAF either mutant (mut)
with late stage, P = 0.123 (suggestive), RAS/BRAF either mut with MGMT
methylated, P = 0.017 (significant); PIK mut with PTEN methylated, P = 0.044
(significant); and PIK mut with CDH13 methylated, P = 0.123 (suggestive).
Concerning RAS/BRAF and stage, 86% of RAS/BRAF either mut tumours, were late
stage, while only 53% of wild type (wt) tumors were late stage. For RAS/BRAF and
MGMT, 76% of RAS/BRAF either mut were MGMT methylated, but 53% of wt
tumors were methylated. PIK mut tumors were also PTEN methylated, and CDH13
methylated. Results are tumor specific as all blood controls were unmethylated resp.
wt.
Conclusion: With PIK, PTEN and CDH13 no significant correlation was noted
with either MGMT unmethylated or methylated nor with RAS/BRAF either wt or
mut. RAS/BRAF correlated significantly with MGMT (p = 0.017), methylated PIK,
PTEN and CDH13 did not correlate with early or late stage. There was a
tendency, of RAS/BRAF mut to be associated with late stage. Of all these markers
none correlates in a significant fashion with early or late stages and as of now,
despite multiple genetic and epigenetic data sets, no predictive statement can be
made.
Disclosure: All authors have declared no conflicts of interest.
549P PROGNOSTIC ROLE OF KRAS MUTATIONS DETECTED BY
HIGH-SENSITIVITY TAQMELT PCR ASSAY IN METASTATIC
COLORECTAL CANCER
J. Garcia Foncillas 1 , S. Zazo 2 , C. Carames 1 , G. Serrano 1 , A. Leon 1 , A. Campos 3 ,
J.I. Martin-Valades 1 , C. Cañadas 2 , T. Hernandez-Guerrero 1 , F. Rojo 2
1 Department of Oncology, University Hospital “Fundacion Jimenez Diaz”, Madrid,
SPAIN, 2 Pathology, Hospital Universitario. Fundación Jimenez Diaz, Madrid,
SPAIN, 3 Department of Oncology, Hospital Infanta Elena, Madrid, SPAIN
Background: KRAS mutation is present in approximately 35-40% of patients with
metastatic colorectal cancer (mCRC) and has been established as a predictive marker
of resistance to anti-EGFR therapy, but its role as prognostic factor is not yet clear.
This study is aimed to analyze the prevalence and the impact in prognosis of
expanded number of KRAS mutations in caucasian mCRC population and the
sensitivity of the TaqMelt PCR assay cobas KRAS Mutation Test.
Methods: A single institution retrospective cohort of 669 consecutive mCRC patients
between 2000-9 with clinical follow-up was studied for frequent 7 mutations in
codons 12/13 by ARMS-scorpion real-time PCR (Therascreen, Qiagen) and TaqMelt
PCR assay cobas KRAS Mutation Test (Roche), which are designed to detect 19
mutations in KRAS codons 12, 13 and 61. DNA was obtained by cobas DNA
preparation kit (Roche) from one single 5um FFPE tissue section and by QIAamp
DNA FFPE Tissue Kit (Qiagen) from 50um of tissue.
Results: KRAS mutation was detected by the cobas KRAS Mutation Test in 41.2%
of mCRC patients and was correlated with poor overall survival (OS) (p = 0.013),
OS from the metastatic diagnosis for metachronous disease (p = 0.025), disease-free
survival for metastatic disease (p = 0.012) and time to progression (p = 0.046).
KRAS mutation was significantly associated with tumor grade (p = 0.025) and liver
as first site of dissemination (p = 0.047). However, KRAS mutations detected by
Therascreen did not impact on prognosis. The median of DNA concentration
obtained by cobas and QIAamp was 120ng/ul and 80ng/ul, respectively. The
frequency of invalid cases was 5.7% (cobas) and 17.9% (Therascreen). Finally,
cobas identified 19.2% additional KRAS mutations not detected by Therascreen.
Next Generation Sequencing by 454 GS FLX+ System analysis is ongoing to
validate discrepant mutations.
Conclusions: The cobas KRAS Mutation Test is a robust and reproducible assay that,
1) obtains superior DNA recovery from very small amount of FFPE tissue; 2) detects
up to 19.2% of mutations not detected by other methods; and, 3) KRAS mutations
detected by cobas correlate with poor outcome in mCRC.
Disclosure: All authors have declared no conflicts of interest.
550P TP, TS AND DPD AS POTENTIAL PREDICTORS OF OUTCOME
FOLLOWING CAPECITABINE PLUS OXALIPLATIN (XELOX) VS.
BOLUS 5-FLUOROURACIL/LEUCOVORIN (5-FU/LV) AS
ADJUVANT THERAPY FOR STAGE III COLON CANCER:
UPDATED BIOMARKER FINDINGS FROM STUDY NO16968
(XELOXA)
H. Schmoll1 , J. Tabernero2 , J.A. Maroun3 , F. De Braud4 , T. Price5 ,E.Van
Cutsem6 , M. Hill7 , S. Hoersch8 , K. Rittweger9 , D. Haller10 1 2
Internal Medicine, University Clinic Halle (Saale), Halle, GERMANY, Medical
Oncology, Vall d’Hebron University Hospital, Barcelona, SPAIN, 3 Medical
Oncology, The Ottawa Hospital Regional Cancer Centre, Ottawa, ON, CANADA,
4
Medical Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano,
Milano, ITALY, 5 Oncology, The Queen Elizabeth Hospital, Adelaide, SA,
AUSTRALIA, 6 Digestive Oncology, University Hospital Gasthuisberg/Leuven,
Leuven, BELGIUM, 7 Medical Oncology, Kent Oncology Centre, Maidstone,
UNITED KINGDOM, 8 Biostatistics, Dr. Manfred Köhler GmbH; working on behalf
of Roche PDBB (Biostatistics), Freiburg, GERMANY, 9 Global Development,
Hoffmann-La Roche Inc., Nutley, NJ, UNITED STATES OF AMERICA,
10
Hematology/oncology, University of Pennsylvania, Philadelphia, PA, UNITED
STATES OF AMERICA
Background: In NO16968, XELOX was superior in terms of disease-free survival
(DFS) and overall survival (OS) to bolus 5-FU/LV as adjuvant therapy for stage III
colon cancer [Schmoll et al. ASCO GI 2012]. Three key enzymes appear to have the
potential to predict efficacy and/or safety of fluoropyrimidine-based treatment:
thymidine phosphorylase (TP), thymidylate synthase (TS), and dihydropyrimidine
dehydrogenase (DPD). We evaluated the association between baseline TP, TS and
DPD and outcome (DFS and OS).
Methods: Patients (pts) with stage III colon cancer received either XELOX (8 cycles,
24w) or bolus 5-FU/LV (Mayo Clinic, 6 cycles, 24w; Roswell Park, 4 cycles, 32w).
The primary study endpoint was DFS; secondary endpoints included OS. TP, TS and
DPD expression levels were determined in formalin-fixed, paraffin-embedded tissues
by RT-PCR, and the median used as a cut-off point: high (above median) vs. low
(below median).
Results: The biomarker population included 498 (26%) of 1886 pts entered (XELOX,
n = 242; 5-FU/LV, n = 256). Baseline demographics, tumour characteristics, cancer
history and efficacy (DFS and OS) were similar to those in the main study
population. Cox regression analysis for DFS is shown in the table. In the XELOX
group pts with low tumour DPD and TP levels and a high TP/DPD ratio appeared
to have significantly better DFS; this effect was not observed with 5-FU/LV.
XELOX 5-FU/LV
Covariate
(high vs. low) HR 95% CI p value HR 95% CI p value
DPD 2.45 1.55–3.86 0.0001 0.69 0.47–1.00 NS
TP 1.73 1.10–2.72 0.0186 0.81 0.55–1.18 NS
TS 0.90 0.58–1.40 NS 0.91 0.62–1.33 NS
TP/DPD ratio 0.54 0.34–0.86 0.0091 0.76 0.51–1.13 NS
Conclusions: These exploratory findings suggest that low tumour levels of DPD may
be predictive for XELOX efficacy when given as adjuvant therapy in pts with resected
stage III colon cancer. There was no correlation between DPD levels and outcome in
the 5-FU/LV group. These data raise the possibility of predictive markers for XELOX
but, until validated prospectively, would currently not have a role in treatment
decisions.
Disclosure: H. Schmoll: Consultant or Advisory Board: Roche Research Funding:
Roche. J. Tabernero: Consultant or Advisory Board: Roche. J.A. Maroun:
Consultant or Advisory Board: Roche. Honoraria: Roche. Research Funding: Roche.
F. De Braud: Honoraria: Roche. T. Price: Consultant or Advisory Board: Roche. E.
Van Cutsem: Research Funding: Roche. M. Hill: Consultant or Advisory Board:
Roche. Honoraria: Roche. Research Funding: Roche. S. Hoersch: Employed by Dr.
Manfred Köhler GmbH/Roche. K. Rittweger: Employed by Hoffmann-La Roche
Inc. D. Haller: Consultant or Advisory Board: Roche. Honoraria: Roche. Research
Funding: Roche.
Volume 23 | Supplement 9 | September 2012 doi:10.1093/annonc/mds397 | ix187