Simple SummaryFMC63-CAR-T cell therapy, an immunotherapy against CD19 protein expressed on malignant B cells, is effective in diffuse large B-cell lymphoma (r/r DLBCL) with complete response in half of the treated patients. Remarkably, there are two germline CD19 antigen variants due to the single nucleotide polymorphism rs2904880 encoding leucine or valine at amino acid position 174 of the CD19 antigen, which is present in half of the global population. We present evidence that this single nucleotide polymorphism in CD19 has a clinical impact on the treatment outcome in FMC63-anti-CD19-CAR-T cell therapy.AbstractChimeric antigen receptor (CAR)-T cell therapy is effective in patients with relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL) with response rates of 63–84% and complete response observed in 43–54%. Common germline variants of the target antigen CD19 may elicit different responses to CAR-T cell therapy. The CD19 gene single nucleotide polymorphism rs2904880 encoding leucine or valine at amino acid position 174 of the CD19 antigen was prevalent in 51% of the studied DLBCL patients. In a retrospective comparative analysis of clinical outcome, there were significant differences in CD19 L174 versus V174 carriers: the median time of progression-free survival was 22 vs. 6 months (p= 0.06), overall survival was 37 vs. 8 months (p= 0.11), complete response rates were 51% vs. 30% (p= 0.05), and refractory disease rates were 14% vs. 32% (p= 0.04). The single nucleotide polymorphism in CD19 was shown to influence the treatment outcome in FMC63-anti-CD19-CAR-T cell therapy, and the CD19 minor allele L174 predicted a favorable treatment outcome.