[Brainlife] FRANCESCHI E et al (2004) - Evaluation of 1p and 19q chromosomal alterations in oligodendroglial neoplasms using microdissection and microsatellite analysis technique and correlations with response to chemotherapy

Evaluation of 1p and 19q chromosomal alterations in oligodendroglial neoplasms using microdissection and microsatellite analysis technique and correlations with response to chemotherapy

E. Franceschi, G. Cavallo, A. Paioli, L. Scopece, R. Degli Esposti, E. Leonardi, F. Spagnolli, A. M. Cremonini, A. Pession, L. Crino

Bellaria Hospital, Bologna, Italy; Bufalini Hospital, Cesena, Italy

Background. Oligodendroglial tumors are chemosensitive diseases.
The evaluation by fluorescence in situ hybridization has been used to assess 1p and 19q alterations that are considered the best chemosensitivity test in these tumors.
Here we show another way to evaluate 1p and 19q chromosomal alterations by using microsatellite analysis that could be considered an useful tool in translational research for the accuracy of this method.

Methods. Patients DNA was extracted from peripheral blood to define the wild type allelic condition, instead tumoral DNA was obtained from laser microdissected cells.
We analized 4 microsatellites on Chr1p and 3 on Chr19q (chosen from sequences described by J.M. Nigro et al., Am J Path 2001); for each locus loss of heterozigosity (LOH), allelic imbalance or chromosomal instability were defined based on allelic peaks pattern.
Chemotherapic regimens allowed were: PCV or Temozolomide or Carboplatin-Etoposide (CE).

Results. At the time of abstract submission we evaluated 21 oligodendroglial tumor adult patients: 4 with oligodendroglioma, 12 with anaplastic oligodendroglioma and 5 with mixed oligoastrocytoma (2 G2 and 3 G3).
In 10 patients both primary and recurrent disease samples were available.
16/21 patients were treated with chemotherapy.
PCV combination was used as first line in 1 patient, Temozolomide was used as first line in 9 patients and CE combination was used as first line in 6 patients.

Conclusions. The evaluation of 1p and 19q status by microsatellite analysis is feasible and provides useful informations about oligodendroglial tumors.
Further results and correlations with response to radiotherapy and chemotherapy, and differences in 1p and 19q LOH pattern between primary and recurrence will be presented at the meeting.

Table 1
	WT	LOH1p	LOH 19q	LOH 1p+19q	Allelic imbalance	Chromosomal instability
O2	2 - 50%	0	0	2 - 50%	1	1
O3	2 - 17%	2 - 17%	1 - 8%	7 - 58%	2	2
OA2	1 - 50%	0	0	1 - 50%	0	0
OA3	2 - 66%	0	0	1 - 33%	0	0