Tumor Genomic Biomarkers as Prognostic Modifiers of Outcomes Following CD19 CAR T-Cell Therapy in Aggressive Large B-Cell Lymphoma: A Systematic Review and Exploratory Meta-Analysis

Background/Objectives: Outcomes after CD19-directed chimeric antigen receptor (CAR) T-cell therapy for relapsed or refractory (R/R) aggressive large B-cell lymphoma (aLBCL) remain heterogeneous. Tumor genomic biomarkers, such as TP53 alteration, MYC/BCL2/BCL6 rearrangement-defined double-hit or triple-hit lymphoma (DHL/THL), cell of origin (COO), and complex karyotype, are established or candidate prognostic factors in conventionally treated lymphoma, but their relevance after CAR T-cell therapy is uncertain. We conducted a systematic review with exploratory meta-analysis of biomarker-stratified outcomes after CD19 CAR T-cell therapy in aLBCL. Methods: We searched MEDLINE, Embase, and Web of Science/BIOSIS (April 2026), with targeted PubMed citation lookup during full-text retrieval (PROSPERO CRD420261350514). Eligible studies enrolled adults with R/R disease treated with protocol-eligible CD19 CAR T-cell therapy and reported prespecified tumor genomic biomarkers with stratified outcomes. Random-effects models, using restricted maximum-likelihood estimation with Hartung–Knapp–Sidik–Jonkman (HKSJ) adjustment, were fitted when at least three comparable, non-overlapping studies provided extractable data. Results: After duplicate removal, 182 records were screened, 37 were assessed for eligibility, and 26 studies were included in the qualitative synthesis; 10 contributed to 4 pooled analyses. DHL/THL-positive disease was associated with worse unadjusted overall survival (OS) (hazard ratio [HR] 1.52; 95% confidence interval [CI], 1.21–1.89; 95% prediction interval (PI), 0.56–4.08), and non-Germinal center B-cell-like (GCB)/ABC COO with worse adjusted progression-free survival (PFS) (HR 1.44; 95% CI, 1.04–2.00; 95% PI, 0.86–2.43). The complete-response analyses for TP53 alteration (OR 1.30; 95% CI, 0.01–156.60) and COO (OR 1.27; 95% CI, 0.24–6.61) were statistically uninformative. No study permitted evaluation of complex karyotypes. Conclusions: Biomarker-stratified evidence after CD19 CAR T-cell therapy is sparse and inconsistently reported. DHL/THL status and non-GCB/activated B-cell-like (ABC) COO showed exploratory survival signals, whereas the TP53 and COO complete-response analyses were uninformative. These biomarkers remain hypothesis-generating rather than validated predictors of CAR T-cell outcome, and standardized, prospective biomarker-stratified reporting is needed.