Tisagenlecleucel in secondary CNS lymphoma

Although chimeric antigen receptor (CAR) T-cell therapy is improving outcomes of patients with non-Hodgkin lymphoma (NHL), it is not indicated for the use in patients with central nervous system (CNS) involvement. Due to concerns around neurotoxicity associated with the use of these products, CNS involvement was an exclusion criterion in previous clinical studies assessing the efficacy and safety of CAR T-cells.¹

Matthew J Frigault from Massachusetts General Hospital, Boston, MA, US, and colleagues recently reported in Blood the results of a retrospective analysis of a small number of patients with high-grade B-cell NHL and secondary CNS involvement, who were treated with commercial tisagenlecleucel (tisa) at the Massachusetts General Hospital.²

Study design

Eight patients with CNS involvement received lymphodepleting chemotherapy with cyclophosphamide (250mg/m²) and fludarabine (25mg/m²) 5, 4, and 3 days before single infusion of tisa (0.6–6.0 x 10⁸ cells). Patients received CNS-directed bridging therapy until lymphodepletion. Initial response was assessed 28 days after infusion by the treating physician in collaboration with a neuro-oncology specialist. Cytokine release syndrome (CRS) and neurotoxicity (NT) were evaluated by the treating physician according to the Lee criteria 2014 and CTCAE v5 and then retrospectively compared with the recent ASTCT 2019 guidelines.^3,4

Main findings

Safety

• Adverse events included grade 1 CRS and 1 NT event in a patient with progressive disease that were considered mainly due to CNS involvement rather CAR-T administration
• Four patients experienced grade 1 neurotoxicity according to Lee 2014 assessment³, which was limited to one patient when assessed using new ASTCT guideline⁴
• Patients did not require tocilizumab or high dose steroids for the management of CRS or NT
• Prophylactic anticonvulsants were administered to all patients and no patients received growth factor support before Day 7
• During therapy with CAR-T, two patients received concomitant maintenance with ibrutinib and one with ibrutinib plus steroids

Efficacy

• CAR T-cell expansion was observed in patients with and without active systemic disease suggesting their ability to reach CNS
• Treatment responses were seen as early as 3–4 weeks after infusion indicating kinetics of CAR T efficacy is similar between CNS and systemic disease
• Two patients died due to progressive disease 3 and 25 days after CAR T-cell infusion. Two further patients achieved a CR with complete resolution of CNS disease. One patient with PR had a CR at Day+180, while another patient with PR had an ongoing response at Day +90

Conclusion

This retrospective analysis points to the viability of tisa as a treatment option for patients with secondary CNS. Patients did not experience increased rates of CRS or NT while CNS responses were seen in half of the patients. The data presented in this retrospective study remain preliminary with a short follow-up but may pave the way for longer and larger prospective studies assessing the use of CAR T-cell therapy for the treatment of CNS disease. The authors are planning to explore this further in a pilot study of tisa in primary lymphoma.