Direct real-time quantitative PCR for measurement of host-cell residual DNA in therapeutic proteins.

•“No DNA extraction” direct qPCR was developed for residual DNA quantification.•Approach combines treatment with PK and SDS followed by Tween 20 in PCR mix.•Direct qPCR for CHO residual DNA was validated according to ICH guidelines.•Method was applied to >20 drug proteins with sensitivity down to 0.1ppb.•Direct qPCR also applicable for residual DNA from other organisms (SP2/0, E. coli).