Treatment of locally recurrent epstein–barr virus‐associated nasopharyngeal carcinoma using the anti‐viral agent cidofovir

Nasopharyngeal carcinoma (NPC) is an Epstein–Barr virus (EBV) associated malignant tumor. Recently, cidofovir, an anti‐viral drug which is an acyclic nucleoside analogue, has been reported to have an anti‐tumor potential. Two patients with NPC, who had previously received multi‐round therapy, were treated with cidofovir. Cidofovir was topically injected in and around the tumor once every 3 weeks (originally 75 mg/ml sulution, diluted to 15 mg/ml just before injection, 37.5 mg of cidofovir at a time). Tumor growth was suppressed for several months around the injection site in each patient. EBV‐encoded RNAs in situ hybridization revealed the reduction of the tumor cell population; however, the EBER expression was still maintained in the NPC tumor cells. Although the anti‐tumor mechanism remains unclear, these results suggest that cidofovir is actually an effective and safe agent for the treatment of NPC. J. Med. Virol. 80:879–882, 2008.