Cidofovir as primary pre-emptive therapy for post-transplant cytomegalovirus infections

Pre-emptive antiviral therapy for CMV infection following allogeneic stem c ell transplantation is an effective strategy for preventing CMV disease. Th is entails the logistic difficulty of daily intravenous therapy with gancic lovir or foscarnet to clinically asymtomatic patients. Cidofovir (CDV) is e ffective against CMV in vitro and has the practical advantage of weekly adm inistration. However, there are limited data on the pre-emptive use of CDV in CMV infections. We carried out a pilot study exploring the efficacy and toxicity of CDV as primary pre-emptive therapy for CMV infections monitored by PCR-based assays. CDV was used at 5 mg/kg with probenecid and hydration , weekly for a maximum of 4 weeks, followed by fortnightly maintenance trea tment. Four patients were treated with CDV and two of them responded. Both the non-responders developed CMV disease. There was no renal toxicity noted in any of the patients, but three patients had severe vomiting and one dev eloped uveitis, which precluded maintenance treatment in the two responders . Following failure of CDV, foscarnet was effective in controlling the CMV infection in both patients, although the infection recurred in both. Thus, larger randomised studies are required before CDV can be recommended as a p rimary pre-emptive therapy for post-transplant CMV infections.