Systematic review and meta-analysis of the association between bridging therapy and outcomes of chimeric antigen receptor T cell therapy in patients with large B cell lymphoma

Abstract

Background

The existing evidence about the impact of bridging therapy (BT) on chimeric antigen receptor (CAR)-T cell therapy in patients with large B cell lymphoma (LBCL) is conflicting. Therefore, we reviewed all available evidence to examine the association between BT and CAR-T therapy outcomes by systematic review and meta-analysis approach.

Methods

Two reviewers independently searched Embase, PubMed, Web of Science, and Cochrane library to identify all records that described BT for LBCL treated with CAR-T. We then applied a fixed- or random-effects meta-analysis to estimate the pooled hazard ratios (HRs) and rate ratio (RRs) for efficacy and safety endpoints and assessed differences across various BT modalities. The Newcastle-Ottawa Scale was used to evaluate study quality.

Results

Twenty-six reports from 24 studies involving 2014 patients were included in the analysis. Pooled results showed that patients requiring BT had significantly worse 1-year overall survival rate (RR = 0.76, 95% confidence interval [CI] 0.68–0.85, P < 0.001), 1-year progression-free survival rate (RR = 0.71, 95% CI 0.60–0.85, P < 0.001), progression-free survival (HR = 1.35, 95% CI 1.07–1.69, P = 0.01), overall response rate (RR = 0.88, 95% CI 0.81–0.95, P = 0.001), complete response rate (RR = 0.78, 95% CI 0.65–0.93, P = 0.005), and grade ≥3 immune effector cell-associated neurotoxicity syndrome (RR = 1.43, 95% CI 1.10–1.87, P = 0.007), and tended to have poorer overall survival (HR = 1.42, 95% CI 0.99–2.02, P = 0.056) and grade ≥3 cytokine release syndrome (RR = 1.59, 95% CI 0.92–2.75, P = 0.096). Prolonged cytopenias were the common toxicity event associated with BT. Radiotherapy may serve as a promising BT option that can provide safe and effective disease control for patients with LBCL before CAR-T infusion. The inconsistency of patient baselines in the current study hindered further comparisons between different BT modalities. Most of the available evidence was rated as low quality because of concerns over low comparability.

Conclusion

BT appears to be associated with comparatively poor efficacy and safety outcomes after CAR-T infusion. However, due to the considerable heterogeneity between the BT and non-BT cohorts at disease baseline, no definitive conclusions can be made for the true impact of BT on CAR-T until further randomized studies are conducted.