Expanding the therapeutic repertoire of epidermal growth factor receptor blockade: radiosensitization

Expression of epidermal growth factor receptor (EGFR) has been associated with radioresistance in cancer. Moreover, tumour cell recovery after irradiation paradoxically occurs, in part, as a result of activation of EGFR signalling by such treatment. A recent article by Huang, Li, Armstrong and Harari provides strong rationale for considering the anti-EGFR agent ZD1839 ('Iressa') as a radiosensitizing strategy. With the use of several in vitro and xenograft models of human squamous cell head and neck carcinoma, ZD1939 was shown to markedly improve radiotherapeutic response, with superior tumour inhibition and delayed tumour regrowth. Mechanisms underlying this effect included anti-proliferative and pro-apoptotic activity, with significant perturbation of tumour angiogenesis.