Measurement of the early level of mdr1 gene expression is a predictive marker of tumour response in breast cancer patients treated by Neo-Adjuvant chemotherapy

The development of resistance to Adriamycin (ADR) remains a major obstacle in the treatment of cancer patients [1]. The main mechanism of resistance termed multidrug resistance (MDR) has consistently been associated with an increased expression of the 170 Kd membrane glycoprotein (Gp170) [2]. Gp170 is encoded by the mdr 1 gene [3] and functions as an energy-dependent drug efflux pump that reduces intracellular drug accumulation [4]. The overexpression of Gp170 and the increased mdr 1 gene transcription found in in vivo and in vitro MDR cells correlate with the level of resistance [5, 6].