Radiotherapy Bridging in Patients With R/R High-Grade Lymphoma Receiving CD19 CAR-T in the UK

Role of radiation in chimeric antigen receptor T-cell therapy for patients with relapsed/refractory non-Hodgkin lymphoma: Current studies and future prospects

Chimeric antigen receptor T-cell (CAR-T) therapy has revolutionized the treatment approach for patients with relapsed/refractory non-Hodgkin lymphoma (R/R NHL). However, the long-term prognosis has been discouraging. Moreover, the urgent resolution of two critical issues is necessary: minimize tumor burden before CAR-T infusion and control fatal toxicities post CAR-T therapy. By combining radiotherapy (RT), the safety and efficacy of CAR-T can be improved. RT can serve as bridging therapy, reducing the tumor burden before CAR-T infusion, thus enabling safe and successful CAR-T infusion, and as salvage therapy in cases of CAR-T therapy failure. This review aims to discuss the current evidence supporting the use of RT in CAR-T therapy for patients with R/R NHL. Although most studies have shown a positive role of RT in combined modality treatments for patients undergoing CAR-T therapy, the synergy gained from these remains uncertain. Furthermore, the optimal dose/fraction and radiation response require further investigation.

Incorporating radiation with anti-CD19 chimeric antigen receptor T-cell therapy for relapsed/refractory non-Hodgkin lymphoma: A multicenter consensus approach

Anti-CD19 chimeric antigen receptor T-cell therapy (CART) has revolutionized the outcomes of relapsed and/or refractory B-cell non-Hodgkin lymphoma. However, CART is still limited by its availability, toxicity, and response durability. Not all patients make it to the CART infusion phase due to disease progression. Among those who receive CART, a significant number of patients experience life-threatening cytokine release syndrome toxicity, and less than half maintain a durable response with the majority relapsing in pre-existing sites of disease present pre-CART. Radiation therapy stands as a promising peri-CART and salvage treatment that can improve the outcomes of these patients. Evidence suggests that bridging radiotherapy prior to CART controls the disease during the manufacturing period, augments response rates and local control, cytoreduces/debulks the disease and decreases the severity of cytokine release syndrome, and may prolong disease-free intervals and survival especially in patients with bulky disease. Consolidative radiotherapy for residual post-CART disease alters the pattern of relapse and improves local recurrence-free and progression-free survivals. Salvage radiotherapy for relapsed post-CART disease has favorable survival outcomes when delivered comprehensively for patients with limited relapsed disease and palliates symptoms for patients with diffuse relapsed disease. The biology of the disease during the peri-CART period is poorly understood, and further studies investigating the optimal timing and dosing of radiation therapy (RT) are needed. In this review, we tackle the most significant challenges of CART, review and propose how RT can help mitigate these challenges, and provide The Mayo Clinic experts' approach on incorporating RT with CART.

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

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.