Chimeric antigen receptor (CAR) modified T cells targeted to CD19 have resulted in unprecedented remission rates for adult and pediatric patients with relapsed and refractory B cell acute ...lymphoblastic leukemia (ALL). With regulatory approval for tisagenlecleucel and many other agents under active investigation, the use of CAR T cells for ALL continues to expand. While some remissions from anti‐CD19 CAR T cells are durable without a consolidative allogeneic stem cell transplantation, CD19 positive and negative relapses remain a significant concern fueling investigations into the biology of CAR T cell persistence and the development of CARTs that target more than 1 antigen. The treatment related toxicities of cytokine release syndrome and neurologic events are potentially life threatening but recent advances have improved understanding and management strategies. This review summarizes outcomes for patients with ALL treated with CD19‐CAR T cells while exploring the field's challenges and future directions.
Chimeric antigen receptor T-cell therapy targeting CD19 (CART19) has expanded the treatment options for patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (ALL). The approval ...of tisagenlecleucel for pediatric and young adult patients with r/r ALL has allowed broader access for some patients, but the treatment of older adults is available (at the time of this writing) only within a clinical trial. High remission rates have been consistently observed with varied CART19 products and treatment platforms, but durability of remissions and thus the potential role of a consolidative allogeneic stem cell transplant (SCT) is more uncertain and likely to vary by product and population treated. The immunologic characteristics of CARTs that confer high response rates also account for the life-threatening toxicities of cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, the severity of which also varies by patient and disease characteristics and product. Further considerations informing a decision to treat include feasibility of leukapheresis and timeline of manufacture, alternative treatment options available, and the appropriateness of a potential consolidative allogeneic SCT. Advances in the field are under way to improve rate and duration of responses and to mitigate toxicity.
T-cell-engaging immunotherapies are exciting new approaches to treat patients with acute lymphoblastic leukemia (ALL). These unique agents, which include blinatumomab, a CD3/CD19 bispecific antibody, ...and chimeric antigen receptor (CAR) modified T cells targeted to CD19 have shown unprecedented remission rates in the relapsed, refractory ALL setting. Cytokine release syndrome (CRS), resulting from the high magnitude of immune activation by these therapies, is the most significant treatment-related toxicity. CRS manifests with fever and malaise and can progress to life-threatening capillary leak with hypoxia and hypotension. The clinical signs of CRS correlate with T-cell activation and high levels of cytokines, including interleukin 6 (IL-6). Tocilizumab, an anti-IL-6 receptor antagonist, is usually effective in the management of severe CRS induced by CAR T cells and has been adopted by most clinical trial programs. With blinatumomab administration, the goal has been to prevent CRS with corticosteroid premedication, disease cytoreduction, and dose adjustments. Collaborative efforts are underway to harmonize the definition and grading system of CRS to allow for better interpretation of toxicities across trials and allow for informed management algorithms.
The adoptive transfer of T lymphocytes reprogrammed to target tumour cells has demonstrated potential for treatment of various cancers
. However, little is known about the long-term potential and ...clonal stability of the infused cells. Here we studied long-lasting CD19-redirected chimeric antigen receptor (CAR) T cells in two patients with chronic lymphocytic leukaemia
who achieved a complete remission in 2010. CAR T cells remained detectable more than ten years after infusion, with sustained remission in both patients. Notably, a highly activated CD4
population emerged in both patients, dominating the CAR T cell population at the later time points. This transition was reflected in the stabilization of the clonal make-up of CAR T cells with a repertoire dominated by a small number of clones. Single-cell profiling demonstrated that these long-persisting CD4
CAR T cells exhibited cytotoxic characteristics along with ongoing functional activation and proliferation. In addition, longitudinal profiling revealed a population of gamma delta CAR T cells that prominently expanded in one patient concomitant with CD8
CAR T cells during the initial response phase. Our identification and characterization of these unexpected CAR T cell populations provide novel insight into the CAR T cell characteristics associated with anti-cancer response and long-term remission in leukaemia.
To describe long-term outcomes of anti-CD19 chimeric antigen receptor T (CART) cells in patients with relapsed or refractory chronic lymphocytic leukemia (CLL).
Between January 2013 and June 2016, 42 ...patients with relapsed or refractory CLL were enrolled in this study and 38 were infused with anti-CD19 CART cells (CART-19). Of these, 28 patients were initially randomly assigned to receive a low (5 × 10
) or high (5 × 10
) dose of CART-19, and 24 were evaluable for response assessment. After an interim analysis, 10 additional patients received the selected (high) dose and of these, eight were evaluable for response. Patients were followed for a median 31.5 months (range, 2 to 75 months).
At 4 weeks, the complete and overall responses for the 32 evaluable patients were 28% (90% CI, 16% to 44%) and 44% (90% CI, 29% to 60%), respectively. The median overall survival (OS) for all patients was 64 months; there was no statistically significant difference between low- and high-dose groups (
= .84). Regardless of dose, prolonged survival was observed in patients who achieved a CR versus those who did not (
= .035), with median OS not reached in patients with CR versus 64 months in those without CR. The median progression-free survival was 40.2 months in patients with CR and 1 month in those without a CR (
< .0001). Toxicity was comparable in both dose groups.
In patients with advanced CLL, a 5 × 10
dose of CART-19 may be more effective than 5 × 10
CART-19 at inducing CR without excessive toxicity. Attainment of a CR after CART-19 infusion, regardless of cell dose, is associated with longer OS and progression-free survival in patients with relapsed CLL.
Initial success with chimeric antigen receptor-modified T cell therapy for relapsed/refractory acute lymphoblastic leukemia is leading to expanded use through multicenter trials. Cytokine release ...syndrome, the most severe toxicity, presents a novel critical illness syndrome with limited data regarding diagnosis, prognosis, and therapy. We sought to characterize the timing, severity, and intensive care management of cytokine release syndrome after chimeric antigen receptor-modified T cell therapy.
Retrospective cohort study.
Academic children's hospital.
Thirty-nine subjects with relapsed/refractory acute lymphoblastic leukemia treated with chimeric antigen receptor-modified T cell therapy on a phase I/IIa clinical trial (ClinicalTrials.gov number NCT01626495).
All subjects received chimeric antigen receptor-modified T cell therapy. Thirteen subjects with cardiovascular dysfunction were treated with the interleukin-6 receptor antibody tocilizumab.
Eighteen subjects (46%) developed grade 3-4 cytokine release syndrome, with prolonged fever (median, 6.5 d), hyperferritinemia (median peak ferritin, 60,214 ng/mL), and organ dysfunction. Fourteen (36%) developed cardiovascular dysfunction treated with vasoactive infusions a median of 5 days after T cell therapy. Six (15%) developed acute respiratory failure treated with invasive mechanical ventilation a median of 6 days after T cell therapy; five met criteria for acute respiratory distress syndrome. Encephalopathy, hepatic, and renal dysfunction manifested later than cardiovascular and respiratory dysfunction. Subjects had a median of 15 organ dysfunction days (interquartile range, 8-20). Treatment with tocilizumab in 13 subjects resulted in rapid defervescence (median, 4 hr) and clinical improvement.
Grade 3-4 cytokine release syndrome occurred in 46% of patients following T cell therapy for relapsed/refractory acute lymphoblastic leukemia. Clinicians should be aware of expanding use of this breakthrough therapy and implications for critical care units in cancer centers.
Patients with multiply relapsed or refractory chronic lymphocytic leukemia (CLL) have a poor prognosis. Chimeric antigen receptor (CAR)-modified T cells targeting CD19 have the potential to improve ...on the low complete response rates with conventional therapies by inducing sustained remissions in patients with refractory B cell malignancies. We previously reported preliminary results on three patients with refractory CLL. We report the mature results from our initial trial using CAR-modified T cells to treat 14 patients with relapsed and refractory CLL. Autologous T cells transduced with a CD19-directed CAR (CTL019) lentiviral vector were infused into patients with relapsed/refractory CLL at doses of 0.14 × 10(8) to 11 × 10(8) CTL019 cells (median, 1.6 × 10(8) cells). Patients were monitored for toxicity, response, expansion, and persistence of circulating CTL019 T cells. The overall response rate in these heavily pretreated CLL patients was 8 of 14 (57%), with 4 complete remissions (CR) and 4 partial remissions (PR). The in vivo expansion of the CAR T cells correlated with clinical responses, and the CAR T cells persisted and remained functional beyond 4 years in the first two patients achieving CR. No patient in CR has relapsed. All responding patients developed B cell aplasia and experienced cytokine release syndrome, coincident with T cell proliferation. Minimal residual disease was not detectable in patients who achieved CR, suggesting that disease eradication may be possible in some patients with advanced CLL.
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