Association of CD7⁺CXCR3⁺ CAR T cells with long-term remission in R/R DLBCL

Background. CAR T-cell therapy is the standard of care for R/R DLBCL, but more than half of patients fail to achieve long-term remission. Identification of cellular biomarkers in CAR T- cell infusion products (IPs) that predict complete remission beyond six months may guide the development of strategies to improve outcomes. Methods. IPs from 13 R/R DLBCL patients were analyzed using a 39-marker mass cytometry panel, comparing cell populations between long-term responders (R) and non-responders (NR). Both unsupervised and supervised analyses were performed. Longitudinal blood samples were analyzed for 30 days to track CAR T-cell subpopulation dynamics. Results. At a median follow-up of 13.5 months, median progression-free survival (PFS) was 13.3 months (95% CI: 9.7-24.3) in R (n=8) versus 3.5 months (95% CI: 0.5-5.4) in NR (n=5). The HR for PFS was 56.67 (95% CI: 7.3-439.3; P=0.0001). A subset of CD3 + CXCR3 + CD7 + CAR T-cells found in both CD4 + and CD8 + populations was significantly enriched in R and expressed higher levels of perforin, granzyme B, and NKG2D (restricted to CD8 + ). NR had more CXCR3 + CD7 + LAG3 + CAR T-cells. CD3, CD7, CXCR3, and NKG2D cell surface levels were higher in R, whereas LAG3, Ki67, and CD71 were elevated in NR. A predictive cut-off ratio of CD3 + CXCR3 + CD7 + LAG3 + CAR + T-cells 1.034 yielded a predictive accuracy of 0.92. Serum CXCL9 and CXCL10 levels were not different between groups. Conclusions. Increased frequency of CAR T-cells expressing CD7, CXCR3 and NKG2D in R versus LAG3 and CD71 in NR emerged as strong correlates of therapeutic outcome.