The dose reduction index (DRI) calculated using the Calcusyn program was used to estimate the ED50 of drugs (267 and/or docetaxel) against the indicated cell lines. The DRI estimates the extent to which the dose of one or more agents in the combination can be reduced to achieve effect levels that are comparable with those achieved with single agents. Black bars indicate the mean ED50 calculated for the drugs when added alone and the grey bars indicate the mean ED50 calculated for the drugs when used in combination. (a) ED50s for QLT0267 (267); when used in combination to treat LCC6 cells the ED50 of 267 can be reduced by 3.6-fold. (b) ED50s for docetaxel; the dose reduction index assessment for docetaxel (Dt) indicated that dose reductions of up to 27.5 fold (LCC6 cells) can be obtained.