Radiation and Chimeric Antigen Receptor T-cell Therapy in B-cell Non-Hodgkin Lymphomas

Total body irradiation primes CD19-directed CAR T cells against large B-cell lymphoma

CD19-targeting chimeric antigen receptor T cells (CART19) have demonstrated significant effectiveness in treating relapsed or refractory large B-cell lymphoma (LBCL). However, they often fail to sustain durable remissions in more than half of all treated patients. Therefore, there is an urgent need to identify approaches to enhance CART19 efficacy. Here, we studied the impact of low-dose radiation on CART19 activity in vitro and find that radiation enhances the cytotoxicity of CART19 against LBCL by upregulating death receptors. Disrupting the FAS receptor diminishes this benefit, indicating that this pathway plays an important role in enhancing the cytotoxic effects of CAR T cells. To further validate these findings, we conducted in vivo studies using a lymphoma syngeneic mouse model delivering total body irradiation (TBI). We observed that delivering TBI at a single dose of 1Gy prior to CAR T cell infusion significantly improved CART19-mediated tumor elimination and increased overall survival rates. Importantly, we characterized several important effects of TBI, including enhanced lymphodepletion, improved T cell expansion and persistence, better intra-tumoral migration, and a more favorable, anti-tumor phenotypic composition of the T cells. In summary, for the first time, we have demonstrated preclinically that administering TBI before CART19 infusion significantly accelerates tumor elimination and improves overall survival. This approach holds promise for translation into clinical practice and serves as a valuable foundation for further research to enhance outcomes for patients receiving CART19 treatment.

Hyper-fractionated radiotherapy as a bridging strategy to enhance CAR-T efficacy by regulating T-cell co-stimulatory molecules in relapsed/refractory diffuse large B-cell lymphoma

Background

Bridging therapy can prevent patients from disease progression while waiting for CAR-T cell preparation. Hyper-fractionated radiotherapy can achieve an effective target dose within a short period, minimize radiation damage, and may modify immune environment compared to conventional radiotherapy.

Aims

This study aims to investigate the efficacy and safety of bridging hyper-fractionated radiotherapy in combination with CAR-T therapy for relapsed/refractory diffuse large B-cell lymphoma. The potential mechanisms were explored.

Methods

This is a prospective pilot study. After T-cell collection, the patients underwent hyper-fractionated radiotherapy at lesion sites with 1.5 Gy twice daily for 10 days before CAR-T cell infusion. Peripheral blood immune cell subsets and quantitative serum proteomics were assessed before radiotherapy and after radiotherapy before CAR-T cell infusion.

Results

A total of 13 patients have been enrolled. The median follow-up time was 6 (3-24) months after CAR-T infusion. At 3-month follow-up, 9/13(69%) patients had CR, 1/13(8%) patient had PR, 1/13(8%) patient remained SD, and 2/13(15%) patients died of disease progression. The local recurrence rate was 1/13(8%). Seven patients have been followed up for more than 6 months, and they remain in CR. The median PFS and OS were not reached. No grade 3-4 CRS or ICANS were reported. After hyper-fractionated radiotherapy, peripheral PD1+CD8+T/T ratio significantly decreased while quantitative serum proteomics profiling showed a decrease in sCD28.

Conclusion

Hyper-fractionated radiotherapy can rapidly control tumor progression sites without delaying the infusion time. This approach can improve the ORR and does not increase the incidence of CRS and ICANS. The mechanism may be related to the regulation of T-cell co-stimulatory molecules, which demands further exploration.

Targeted and cellular therapies in lymphoma: Mechanisms of escape and innovative strategies

The therapeutic landscape for lymphomas is quite diverse and includes active surveillance, chemotherapy, immunotherapy, radiation therapy, and even stem cell transplant. Advances in the field have led to the development of targeted therapies, agents that specifically act against a specific component within the critical molecular pathway involved in tumorigenesis. There are currently numerous targeted therapies that are currently Food and Drug Administration (FDA) approved to treat certain lymphoproliferative disorders. Of many, some of the targeted agents include rituximab, brentuximab vedotin, polatuzumab vedotin, nivolumab, pembrolizumab, mogamulizumab, vemurafenib, crizotinib, ibrutinib, cerdulatinib, idelalisib, copanlisib, venetoclax, tazemetostat, and chimeric antigen receptor (CAR) T-cells. Although these agents have shown strong efficacy in treating lymphoproliferative disorders, the complex biology of the tumors have allowed for the malignant cells to develop various mechanisms of resistance to the targeted therapies. Some of the mechanisms of resistance include downregulation of the target, antigen escape, increased PD-L1 expression and T-cell exhaustion, mutations altering the signaling pathway, and agent binding site mutations. In this manuscript, we discuss and highlight the mechanism of action of the above listed agents as well as the different mechanisms of resistance to these agents as seen in lymphoproliferative disorders.

Influence of Culture Conditions on Ex Vivo Expansion of T Lymphocytes and Their Function for Therapy: Current Insights and Open Questions

Ex vivo expansion of T lymphocytes is a central process in the generation of cellular therapies targeted at tumors and other disease-relevant structures, which currently cannot be reached by established pharmaceuticals. The influence of culture conditions on T cell functions is, however, incompletely understood. In clinical applications of ex vivo expanded T cells, so far, a relatively classical standard cell culture methodology has been established. The expanded cells have been characterized in both preclinical models and clinical studies mainly using a therapeutic endpoint, for example antitumor response and cytotoxic function against cellular targets, whereas the influence of manipulations of T cells ex vivo including transduction and culture expansion has been studied to a much lesser detail, or in many contexts remains unknown. This includes the circulation behavior of expanded T cells after intravenous application, their intracellular metabolism and signal transduction, and their cytoskeletal (re)organization or their adhesion, migration, and subsequent intra-tissue differentiation. This review aims to provide an overview of established T cell expansion methodologies and address unanswered questions relating in vivo interaction of ex vivo expanded T cells for cellular therapy.