Sabato 27 ottobre 2012 - Pacini Editore

252
Predictive factors in colorectal carcinoma
beyond KrAS
A. Scarpa, V. Corbo
Dipartimento di Patologia e Diagnostica, Policlinico GB Rossi, Università
di Verona
EGFR targeted monoclonal antibodies (cetuximab and panitumumab)
have paved the way to the individualized treatments
of metastatic colorectal cancer (mCRC). KRAS mutations
emerged as the major negative predictor of response to those
therapies. Mutations of KRAS occur in about 40% of mCRCs
thus enabling for the selection of patients that might respond
to anti-EGFR treatments. Unfortunately, the concept of a
binary relationship between mutations in a given gene and
response to therapy is not valid for mCRCs. Indeed, KRAS
mutations testing showed high specificity but low sensitivity.
A genetic basis for that failure has been recently demonstrated
by studies focusing on additional genes involved in downstream
EGFR signaling. Oncogenic mutations of BRAF or
PIK3CA and mutations of the tumor suppressor PTEN have
emerged as additional negative predictive markers. mCRCs
lacking alterations of those genes (defined “quadruple negative”)
have the highest probability to respond to anti-EGFR
therapies. Very recent evidences showing that distinct mutations
in a single cancer gene (such as codon-specific mutations
of PIK3CA) might have different roles in response
to therapy further complicated the scenario. However, the
effective translation of these findings into clinical practice
will empower the selection of patients eligible for anti-EGFR
therapies. At the same time, despite genetic analysis of tumor
samples are now part of the work of most pathology departments,
the uncovering of the genetic milieu of individual
colorectal cancer pose new challenges: testing simultaneously
multiple genes in individual tumors using limited amount
of tissue samples such as biopsy. The development of very
sensitive and informative assay platforms is therefore mandatory.
In line with this, a newly founded European Consortium
coordinates a multi-institutional effort for the development
and the implementation of a dedicated multi-gene panel test
to be used for therapy decision and prognostic stratification
in colon cancer.
Predittività nel carcinoma mammario:
uno sguardo oltre i fattori convenzionali
A. Sapino
Paper not received
CONGRESSO aNNualE di aNatOmia patOlOGiCa SiapEC – iap • fiRENzE, 25-27 OttOBRE 2012
Sabato 27 ottobre 2012
Sala Botticelli - 11.30-12.30
Fattori predittivi molecolari
Moderatori: Antonio Marchetti (Chieti), Giancarlo Troncone (Napoli)
Analysis of egfr mutations in circulating tumor
cells by massively parallel sequencing
F. Buttitta
Cardiovascular and Oncological Molecular Medicine Unit, Ce.S.I.
(Centro Scienze dell’Invecchiamento)- University “G. d’Annunzio”,
Chieti
The management of patients with advanced non-small cell
lung cancer (NSCLC) is currently based on the assessment of
EGFR mutations. The mutation test is routinely performed on
resected neoplastic tissues, biopsies or cytological samples. For
several patients with advanced lung cancer or with progressive
disease, it can be a challenge to obtain biological material for
molecular analysis. Circulating tumor cells (CTC) are rare
cells detectable in the blood of neoplastic patients and their
enumeration has been shown to correlate with clinical outcome
in patients with several types of malignancies. Furthermore,
CTCs appear to be a non-invasive source of tumor cells, providing
real-time information on biomarker status without the
need for invasive re-biopsy. Over the last few years, a set of
novel technologies for CTCs detection has emerged, including
nucleic-acid-based and cytometric approaches. The first class
of methods is predominantly represented by very sensitive
PCR-based techniques for the detection of specific DNA or
RNA sequences. More recently, there has been a shift towards
cytometric procedures because these methods allow the cells
to maintain integrity in order to be identified and counted. The
most widely used CTC detection platform is the CellSearch
system (Veridex LLC, Huntingdon Valley, PA, USA), which
is the only technology to have received FDA approval for the
enumeration of CTC in whole blood of patients affected by
breast, prostate and colon cancer. CellSearch platform utilizes
a semi-automated immunomagnetic bead-based separation to
enrich CTCs. However, CTCs isolation is until now a challenge,
because they occur at very low concentration of one cell
in the background of millions of white blood cells. Therefore,
their molecular characterization requires extremely sensitive
and specific procedures. We decided to analyze EGFR mutation
in CTCs isolated from plasma of a series of lung cancer
patients. The CTCs enriched by CellSearch platform were
subsequently analyzed by massively parallel sequencing on GS
Junior 454-Roche, a novel approach that can allow the detection
of genetic mutations even if they are present in a minority
of DNA molecules. This platform is able to run thousands of
gene sequences per sample from a single PCR and therefore
it is an ideal approach for gene sequencing of rare DNA molecules,
such as those extracted from circulating tumor cells in
a high background of white cells.
Le mutazioni del gene BrAF nel trattamento del
melanoma metastatico
F. Castiglione
Paper not received