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Complications occurring after lymphodepleting chemotherapy (LDC) may delay chimeric antigen receptor (CAR) T-cell infusion. The effect of these delays on clinical outcomes is unclear. We performed a retrospective analysis of 240 patients with relapsed/refractory large B-cell lymphoma treated with standard-of-care axicabtagene ciloleucel (axi-cel) and identified 40 patients (16.7%) who had delay in axi-cel infusion. Of these, 85% had delay due to infection. At time of LDC initiation, patients with delayed infusion had lower absolute neutrophil count (P=0.006), lower platelets (P=0.004), lower hemoglobin (P<0.001) and higher C-reactive protein (P=0.001) than those with on-time infusion. Patients with delayed infusion had lower day 30 overall response rates (59.0% vs. 79.4%; P=0.008) and shorter median progression-free survival (PFS) (3.5 vs. 8.2 months; P=0.002) and overall survival (7.8 vs. 26.4 months; P=0.046) than those with on-time infusion. The association with PFS was maintained on multivariate analysis. There was also an association between extent of delay and survival, with shorter median PFS in patients who had delays of 2-5 days (1.8 vs. 8.2 months; P=0.001) and >5 days (4.6 vs. 8.2 months; P=0.036), but not 1 day (5.7 vs. 8.2 months; P=0.238). Following propensity score matching, patients with delayed infusion continued to have shorter median PFS (3.5 vs. 6.0 months; P=0.015). Levels of pro-inflammatory cytokines on day of infusion were significantly higher in patients with delayed infusion. Together, these findings suggest that delays in CAR T-cell administration after initiation of LDC are associated with inferior outcomes. Further studies are needed to guide strategies to improve efficacy in such patients.

Conditioning chemotherapy (CCT) has been shown to be essential for optimal efficacy of chimeric antigen receptor (CAR) T-cell therapy. Here, we determined whether the change in absolute lymphocyte count, referred to as delta lymphocyte index (DLIx), may serve as a surrogate marker for pharmacodynamic effects of CCT and whether it associated with germline genetic variants in patients with large B-cell lymphoma (LBCL). One-hundred and seventy-one patients were included, of which 86 (50%) received bridging therapy post-leukapheresis. Median DLIx was 0.5 × 10 9 /L (range, 0.01-2.75 × 10 9 /L) and was significantly higher in patients who achieved complete response (p = 0.04). On multivariate analysis, low DLIx was associated only with use of bridging therapy (odds ratio 0.4, 95% CI 0.2-0.8, p = 0.007). Low DLIx was independently associated with shorter progression-free (p = 0.02) and overall survival (p = 0.02). DLIx was associated with genetic variations related to drug metabolism and macrophage biology such as ABCB1, MISP and CPVL. The impact of CCT on lymphocyte count is affected by use of bridging therapy but change in lymphocyte count is independently associated with efficacy. Studies aimed at investigating macrophage biology in this setting may suggest strategies to increase the efficacy of CCT and improve outcomes., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)