A novel generation 1928zT2 CAR T cells induce remission in extramedullary relapse of acute lymphoblastic leukemia

Abstract

BackgroundAnti-CD19 chimeric antigen receptor (CAR) T cells have shown promise in the treatment of B cell acute lymphocytic leukemia (B-ALL). However, its efficacy in B-ALL patients with extramedullary involvement is limited due to poor responses and neurotoxicity. Here, we utilized a third generation of CAR T cell vector, which contains the Toll/interleukin-1 receptor (ITR) domain of Toll-like receptor 2 (TLR2), to generate 1928zT2 T cells targeting CD19, and evaluated the efficacy of 1928zT2 T cells in relapse or refractory B-ALL patients with extramedullary involvement.Methods1928zT2 T cells were generated by 19-28z-TLR2 lentiviral vector transfection into primary human T lymphocytes. The anti-leukemia effect of 1928zT2 T cells were determined by killing assays and in xenografts. Three patients diagnosed as relapse or refractory ALL with extramedullary involvement were infused with 1928zT2 T cells, and the clinical responses were evaluated by BM smear, B-ultrasonography, PET/CT, histology, flow cytometry, qPCR, ELISA, and luminex assay.Results1928zT2 T cells exhibited enhanced effector function against CD19+ leukemic cells in vitro and in a xenograft model of human extramedullary leukemia. Notably, the 1928zT2 T cells eradicated extramedullary leukemia and induced complete remission in the three relapse and refractory ALL patients without serious adverse effects. 1928zT2 T cells expanded robustly in the circulation of these three patients and were detected in the cerebrospinal fluid of patient 3. These three patients experienced cytokine release syndrome (CRS) with grade 2 or 3, which remitted spontaneously or after tocilizumab treatment. None of the three patients suffered neurotoxicity or needed further intensive care.ConclusionsOur results demonstrate that 1928zT2 T cells with TLR2 incorporation augment anti-leukemic effects, particularly for eradicating extramedullary leukemia cells, and suggest that the infusion of 1928zT2 T cells is an encouraging treatment for relapsed/refractory ALL patients with extramedullary involvement.Trial registrationClinicalTrials.gov identifier NCT02822326. Date of registration: July 4, 2016.

Selecting costimulatory domains for chimeric antigen receptors: functional and clinical considerations

“…56,57 In 10 out of 11 patients with active disease, greater expansion (up to 40-fold) of third-generation CAR T cells compared to second-generation CAR T cells was seen, and third-generation CAR T cells remained detectable at higher levels up to 160 days postinfusion. 53 Despite promising preclinical results and greater proliferative potential in early clinical trials, the clinical benefits of combining costimulatory domains within third-generation CAR T cells are yet to be conclusively demonstrated. Considering the results of Cheng et al, 25 who reported no significant difference between two-second-generation (CD28 vs 4-1BB) CAR T cells co-infused in patients, Ramos et al 56 concluded that third-generation CAR T cell therapy may be effective in the eradication of minimal residual disease and lead to longer, more durable remissions.…”

“…73 Moreover, increasing clinical experience in the early recognition and management of CRS and neurotoxicity is likely to reduce the incidence of severe toxicities, the early introduction of anti-IL-6 therapy and corticosteroids being associated with lower rates of life-threatening complications. 53,56,58 However, the number of recipients of third-generation CAR T cells in the published literature is low, and the results of additional trials, including some currently recruiting studies, will be needed to accurately assess toxicity risk (see Figure 4). CRS in particular often occurs during or near the peak of CAR T cell expansion.…”

“…For example, a number of Toll-like receptors (TLRs), as well as the TLR adaptor molecule MyD88, are expressed by activated T cells, and TLRs can serve as costimulatory molecules within T cells, augmenting T cell cytokine production and cytokine production in response to TCR stimulation. 52,53 TLR2 stimulation of human T cells, for example, leads to enhanced Akt and Erk1/Erk2 phosphorylation in the presence of TCR stimulation. 52 The incorporation of a TLR2 endodomain into CD28-costimulated second-generation CARs enhanced CAR T cell activity against CD19 and mesothelin-expressing tumors.…”

Improving the safety of CAR-T cell therapy by controlling CRS-related coagulopathy

“…In CD19-positive B cell malignancies, approximately 90% acute lymphoblastic leukemia (ALL) patients [1][2][3][4][5][6][7][8][9][10][11][12] and 70% lymphoma patients [13][14][15][16][17][18] can get remissions through CD19-specific CAR-T therapy. Encouragingly, two of the CD19-targeted CAR-T therapies, Kymriah and Yescarta, have been approved to treat relapsed/refractory (r/r) pediatric, young adult B cell ALL (B-ALL), and certain adult non-Hodgkin lymphomas (NHL) by the US Food and Drug Administration in 2017.…”

A review of chimeric antigen receptor T-cells in lymphoma

“…The exact mechanism of CAR-T induced neurotoxicity remains unclear but is thought to be at least partially driven by excessive cytokine production like CRS. The absence of CAR T-cells in cerebrospinal fluid in some cases of ICANS indicates an indirect mechanism for this process with diffusion of cytokines across the blood brain barrier being the most widely accepted mechanism of injury [25]. High levels of Granzyme B, which has previously been linked to neuronal injury, as well as IL-12 and IL-15 correlate with more severe ICANS [26].…”