Proteomic Study of Diffuse Large B-Cell Lymphoma Identifying Proteins Associated with R-CHOP Response

Background/Objectives: Diffuse large B-cell lymphoma (DLBCL) is a molecularly and pathogenically heterogenous disease with varying clinical outcomes, as reflected by the significant number of patients who develop relapse/refractory disease (rrDLBCL) following standard treatment with the combined R-CHOP regimen. The molecular background of rrDLBCL is not yet fully understood, and prognostic and/or companion diagnostic biomarkers for identification and treatment stratification of these patients are in high demand. Methods: This exploratory study used comprehensive proteomic data to identify proteins associated with treatment response. Proteome profiles of DLBCL cells were analyzed through groupwise comparison between cell lines with a resistant or sensitive response to rituximab, cyclophosphamide, doxorubicin, and vincristine. Their responses were determined using subsequent drug response screens, mimicking the conditions of diagnostic samples prior to treatment. Results: A total of 98 differentially abundant proteins, including NSFL1C, GET4, PCNA, and SMC5, were found between resistant and sensitive cells. These same 98 proteins were examined in two cohorts of DLBCL patients, leading to the identification of 16 proteins whose expression was consistently associated with treatment response both in vitro and in patient tissue samples. Among these, GET4 and NSFL1C showed the highest enrichment in R-CHOP resistant patients compared to sensitive responders. In the cell line study, GET4 was enriched in cyclophosphamide-resistant cell lines and NSFL1C enriched in vincristine-resistant cell lines, associating GET4 and NSFL1C enrichment in patient samples to responsiveness to cyclophosphamide and vincristine, respectively. Enrichment of DNA damage repair proteins was observed within the differential proteins, highlighting the need to investigate DNA damage repair involvement in treatment responses. Conclusions: This study identifies 16 proteins with concordant treatment response specificity in DLBCL cell lines and lymphoma tissue patient samples, suggesting their potential as prognostic markers for DLBCL.