Diffuse large B-cell lymphoma (DLBCL) is a molecularly and pathogenically heterogenous disease with varying clinical outcomes which is reflected in the substantial group of patients developing relapse/refractory disease (rrDLBCL) after standard treatment with the combinatory regimen R-CHOP. The molecular background of developing rrDLBCL is yet to be fully understood and prognostic and/or companion diagnostic biomarkers for identification, treatment stratification and prediction of adverse treatment effects of these patients are in high demand. Therefore, this exploratory study aims to use comprehensive proteomic relative quantitative data to identify proteins that are associated with treatment response. Proteome profiles of untreated DLBCL cells were analyzed by groupwise comparison between cell lines having poor and good response to rituximab, cyclophosphamide, doxorubicin and vincristine, respectively, determined by subsequent drug response screen.