Clinical trials involving the oncolytic virus, reovirus: ready for prime time?

The use of oncolytic viruses as a potential cancer therapeutic has been studied extensively over the past 15 years and is now in Phase III human clinical testing. One of the most promising of the viruses is the nonattenuated reovirus type-3 Dearing (RT3D; Reolysin(®), Oncolytics Biotech Inc., AB, Canada). The virus is a laboratory strain of a ubiquitous common environmental virus commonly infecting the respiratory and GI tracts of humans without major sequelae. The Phase I/II clinical trial conducted by Karapanagiotou et al. involved dose escalation of Reolysin to 3 × 10(10) tissue culture infectious dose 50 (TCID(50)) daily for 5 days in combination with paclitaxel (175 mg/m(2)) and carboplatin (area under the curve 5) given on day 1 every 3 weeks. Maximum tolerated dose was not reached in the dose-escalation phase and was only limited by manufacturing concentration limitation. Efficacy was suggested in this heavily pretreated head and neck cancer predominate patient population with a 26.9% response rate (seven out of 26 evaluable patients) of the 34 patients intended to treat. Although this was not a randomized trial, the fact that many of the patients (83%) had already received a platinum agent and subsequently progressed and then responded is of interest.