Aim of the study: Chimeric antigen receptor T (CAR-T) cells are a powerful form of immune-cell therapy for patients with relapsed/refractory B-cell lymphoma and acute B lymphoblastic leukaemia. CAR-T cells have been commercially available in Switzerland since 2018. Because of the complexity and costs of this treatment it is critical to review patient outcomes in real-world settings, to examine whether the promising results from pivotal trials can be reproduced and to identify clinical parameters that determine their efficacy.
Methods: Here we present results of a retrospective study analysing outcomes of patients treated with CAR-T cells in a single academic centre in Switzerland during the first two years after commercial approval (BASEC-No. 2020-02271). Cytokine release syndrome (CRS), immune-cell associated neurotoxicity syndrome (ICANS), responses to treatment, ancillary laboratory studies and administrative specifics of CAR-T treatment were examined and are discussed.
Results: From October 2018 to August 2020 CAR-T cell therapy was evaluated in 34 patients, mostly with relapsed/refractory aggressive B-cell lymphoma (87% had refractory disease). Thirty-one patients underwent leukapheresis. Three of 31 patients (9.6%) died of rapid disease progression before the CAR-T cell product was delivered, two patients were enrolled into a clinical trial, three patients were not given CAR-T cells for other reasons. Ultimately, 23 patients were infused with a commercial CAR-T cell product and included in this analysis. Fourteen (61%) patients received bridging therapy while waiting for a median of 41 days (range 31-62) for delivery of the CAR-T cell product. Toxicity and severe side effects were rare (CRS >3 in 13%, ICANS > grade 3 in 10% of patients), manageable and resolved completely thereafter. The best overall response rate was 65%, with complete responses in 38% of lymphoma patients. At 12 months postinfusion, 61% of patients were alive and 35% progression free. With a median follow-up of 14 months, 13/23 (56%) patients were alive at the time of writing.
Conclusion: CAR-T cell therapy proved to be safe and manageable under adequate hospital conditions. Outcomes resemble results from pivotal trials. The majority of patients was heavily pretreated and refractory at the time of CAR-T cell infusion. Patient selection, time point of leukapheresis, bridging strategies and timing of CAR-T cell infusion may be critical to further improve outcomes.