Mitochondrial mass in pre-lymphodepletion T cells predicts early response to CAR-T therapy in relapsed/refractory non-Hodgkin lymphoma

Abstract Background: Response heterogeneity to CAR-T therapy in relapsed/refractory non-Hodgkin lymphoma (R/R NHL) remains a major clinical challenge. This study investigates mitochondrial metabolism biomarkers—mitochondrial mass (MM) and membrane potential (MMP)—in T-cell subsets as potential predictors of CAR-T efficacy. Methods: In this prospective cohort study (March 2023 to May 2025), 45 R/R NHL patients receiving CAR-T therapy were enrolled. MM and MMP of CD4⁺/CD8⁺ T-cell subsets (naïve [Tn], effector [Tef], central memory [Tcm], effector memory [Tem]) and absolute counts were quantified at pre-lymphodepletion and post-infusion timepoints (Day 7 [D7], Day 14 [D14], Month 1 [M1]). The primary endpoint was 3-month objective response rate (ORR-3; Lugano 2014 criteria). Three patients lost to early follow-up were excluded, leaving 42 patients for analysis. Results: The cohort (n=42) had median age 59 years (range 19–79), with 25 males and 17 females. Histological subtypes included DLBCL (n=38, 12 transformed), follicular lymphoma (n=3), and T-cell/histiocyte-rich large B-cell lymphoma (n=1). Twenty-nine patients received single-target CAR-T while 13 received dual-target products, with 30 achieving ORR-3. In the 28 patients with pre-lymphodepletion samples, MM was significantly higher in responders across multiple subsets (CD4⁺ Tn, Tef, Tcm, Tem; CD8⁺ Tef, Tcm, Tem; all p<0.05) with no differences in MMP or absolute counts. Multivariable analysis adjusted for age, transformed histology, primary refractoriness, and bulky disease confirmed independent associations for CD4⁺ Tn high MM (OR=7.78, 95%CI:1.41–42.80; p=0.018), CD4⁺ Tef high MM (OR=17.59, 95%CI:1.27–242.75; p=0.032), and CD8⁺ Tef high MM (OR=18.66, 95%CI:1.10–318.14; p=0.043). The combined prediction model achieved an AUC of 0.81 (95%CI:0.61–1.00) for ORR-3. No post-infusion parameters (D7/D14/M1) correlated with response. Conclusion: Superior mitochondrial mass in pre-lymphodepletion CD4⁺ Tn/Tef and CD8⁺ Tef subsets independently associates with improved CAR-T response, suggesting utility as an early efficacy biomarker. Despite promising discriminative capacity, wide confidence intervals necessitate validation in larger prospective cohorts.