Tisagenlecleucel is a CD19 chimeric antigen receptor (CAR) T-cell therapy approved for treatment of pediatric and young adult patients with relapsed/refractory acute lymphoblastic leukemia (ALL) and adults with non-Hodgkin lymphoma (NHL). The initial experience with tisagenlecleucel in a real-world setting from a cellular therapy registry is presented here. As of January 2020, 511 patients were enrolled from 73 centers, and 410 patients had follow-up data reported (ALL, n = 255; NHL, n = 155), with a median follow-up of 13.4 and 11.9 months for ALL and NHL, respectively. Among patients with ALL, the initial complete remission (CR) rate was 85.5%. Twelve-month duration of response (DOR), event-free survival, and overall survival (OS) rates were 60.9%, 52.4%, and 77.2%, respectively. Among adults with NHL, the best overall response rate was 61.8%, including an initial CR rate of 39.5%. Six-month DOR, progression-free survival, and OS rates were 55.3%, 38.7%, and 70.7%, respectively. Grade ≥3 cytokine release syndrome and neurotoxicity were reported in 11.6% and 7.5% of all patients, respectively. Similar outcomes were observed in patients with in-specification and out-of-specification products as a result of viability <80% (range, 61% to 79%). This first report of tisagenlecleucel in the real-world setting demonstrates outcomes with similar efficacy and improved safety compared with those seen in the pivotal trials.

PURPOSE Tisagenlecleucel is a CD19-specific chimeric antigen receptor T-cell therapy, US Food and Drug Administration–approved for children, adolescents, and young adults (CAYA) with relapsed and/or refractory (RR) B-cell acute lymphoblastic leukemia (B-ALL). The US Food and Drug Administration registration for tisagenlecleucel was based on a complete response (CR) rate of 81%, 12-month overall survival (OS) of 76%, and event-free survival (EFS) of 50%. We report clinical outcomes and analyze covariates of outcomes after commercial tisagenlecleucel. METHODS We conducted a retrospective, multi-institutional study of CAYA with RR B-ALL across 15 US institutions, who underwent leukapheresis shipment to Novartis for commercial tisagenlecleucel. A total of 200 patients were included in an intent-to-treat response analysis, and 185 infused patients were analyzed for survival and toxicity. RESULTS Intent-to-treat analysis demonstrates a 79% morphologic CR rate (95% CI, 72 to 84). The infused cohort had an 85% CR (95% CI, 79 to 89) and 12-month OS of 72% and EFS of 50%, with 335 days of median follow-up. Notably, 48% of patients had low-disease burden (< 5% bone marrow lymphoblasts, no CNS3, or other extramedullary disease), or undetectable disease, pretisagenlecleucel. Univariate and multivariate analyses associate high-disease burden (HB, ≥ 5% bone marrow lymphoblasts, CNS3, or non-CNS extramedullary) with inferior outcomes, with a 12-month OS of 58% and EFS of 31% compared with low-disease burden (OS; 85%, EFS; 70%) and undetectable disease (OS; 95%, EFS; 72%; P < .0001 for OS and EFS). Grade ≥ 3 cytokine release syndrome and neurotoxicity rates were 21% and 7% overall and 35% and 9% in patients with HB, respectively. CONCLUSION Commercial tisagenlecleucel in CAYA RR B-ALL demonstrates efficacy and tolerability. This first analysis of commercial tisagenlecleucel stratified by disease burden identifies HB preinfusion to associate with inferior OS and EFS and increased toxicity.

Chimeric antigen receptor (CAR) T-cells provide a therapeutic option in hematologic malignancies. However, treatment failure after initial response approaches 50%. In allogeneic hematopoietic cell transplantation, optimal fludarabine exposure improves immune reconstitution, resulting in lower nonrelapse mortality and increased survival. We hypothesized that optimal fludarabine exposure in lymphodepleting chemotherapy prior to CAR T-cell therapy would improve outcomes. In a retrospective analysis of relapsed/refractory B-cell acute lymphoblastic leukemia patients undergoing CAR T-cell (tisagenlecleucel) infusion after cyclophosphamide/fludarabine lymphodepleting chemotherapy, we estimated the fludarabine exposure as area-under-the-curve (AUC;mg*hr/L) using a validated population-pharmacokinetic model. Fludarabine exposure was related to overall survival (OS), cumulative incidence of relapse (CIR), and a composite endpoint (loss of B-cell aplasia (BCA) or relapse). Eligible patients (n=152) had a median age of 12.5 years (range &lt;1-26), response rate of 86% (131/152), 12-month OS of 75.1% (95%-CI: 67.6-82.6%), and 12-month CIR of 36.4% (95%-CI: 27.5-45.2%). Optimal fludarabine-exposure was determined as an AUC≥13.8mg*hr/L. In multivariable analyses patients with an AUC&lt;13.8mg*hr/L had a 2.5-fold higher CIR (HR=2.45 [1.34-4.48]; P=0.005) and a twofold higher risk of relapse or loss of BCA (HR=1.96 [1.19-3.23]; P=0.01) compared to those with optimal fludarabine exposure. High preinfusion disease burden was also associated with an increased risk of relapse (HR=2.66 [1.45-4.87]; P=0.001) and death (HR=4.77 [2.10-10.9]; p&lt;0.001). Personalized PK-directed dosing to achieve optimal fludarabine exposure should be tested in prospective trials and based on this analysis may reduce disease relapse after CAR T-cell therapy.

Introduction: Chimeric Antigen Receptor (CAR) T cell therapy targeting CD19 has shifted our treatment approach for relapsed and refractory (r/r) pediatric B cell acute lymphoblastic leukemia (ALL). The landmark ELIANA pediatric trial studying tisagenlecleucel, CD19-specific CAR T cells, demonstrated a complete response (CR) rate of 81% in 75 infused patients and 12 month overall survival (OS) and event-free survival (EFS) rates of 76% and 50% respectively. Cytokine release syndrome (CRS) and neurotoxicity rates of 77% and 40% were respectively reported. In August 2017, the FDA approved tisagenlecleucel for B-cell ALL that is refractory or in second or greater relapse in patients up to age 25. With CAR commercialization, institutions deliver tisagenlecleucel without the regulation of a clinical study and practices relating to CAR delivery and reporting remain heterogeneous. Here, we report real world clinical outcomes using commercially available tisagenlecleucel for pediatric r/r B-ALL. Methods and Results: Retrospective data were collected from PRWCC member institutions (n=15) and included 200 patients. This includes 15 (7.5%) patients not infused due to manufacturing failure (n=6), death from disease progression and/or toxicity (n=7), or physician discretion following disease remission from prior therapy(n=2). The remaining 185 patients (92.5%) were infused with tisagenlecleucel, including 87% (161) receiving standard-of-care CAR T cell products meeting manufacturing release criteria and 13% (24) receiving CD19-CAR T cells manufactured by Novartis and provided on the managed access program (NCT03601442; n=14) or with single-patient IND approval (n=10). At time of CAR T cell infusion, median age was 12 years (range 0-26) with 40% females and 60% males. Median duration of follow-up at time of analysis was 11.2 months (range 0.2-28.8). The CR rate at 1 month follow up was 79% (156/198) on an intent-to-treat basis and 85% (156/184) among evaluable infused patients. Of infused patients achieving morphologic CR with available testing, 97% (148/153) were negative for MRD by flow cytometry. Duration of remission at 6 and 12 months among patients who achieved CR was 75% and 63% respectively, with 35% (55/156) of responders experiencing relapse. At time of relapse, 41% (21/51) of evaluable patients had relapse with CD19- disease and 59% (30/51) had continued CD19 expression. OS and EFS rates were 85% and 64% at 6 months and 72% and 51% at 12 months, respectively. CRS and neurotoxicity of any grade were seen in 60% (111/184) and 22% (39/181) of evaluable patients with ≥ grade 3 CRS and neurotoxicity rates of 19% (35/184) and 7% (12/181) respectively. One grade 5 CRS and 1 grade 5 neurotoxicity (intracranial hemorrhage) were reported. Post infusion toxicity management included tocilizumab in 26% (47/184) and systemic steroids in 14% (25/184) of patients. Among 181 infused patients with documented disease burden, 51% (95) had high burden (HB) disease , as defined by &gt;5% bone marrow lymphoblasts, peripheral blood lymphoblasts, CNS3 status or non-CNS extramedullary (EM) site of disease; 22% (40) had low burden (LB) disease, defined by detectable disease not meeting the HB criteria; and 25% (46) had no detectable disease (NDD) at time of last evaluation prior to CAR infusion. The morphologic CR rate was lower at day 28 in HB vs. LB and NDD (74% vs. 98% and 96%) and the OS and EFS were lower among patients with HB at 6 mo [OS; 75% (HB), 94%(LB), 98% (NDD), EFS; 50% (HB), 86% (LB), 75%(NDD), p&lt;0.0001] and 12 mo [OS; 58% (HB), 85% (LB), 95% (NDD), EFS; 34% (HB), 69%(LB), 72%(NDD), p&lt;0.0001]. Multivariate analysis will be presented at the meeting. Conclusions: This retrospective, multi-institutional analysis describes real world outcomes using tisagenlecleucel to treat pediatric r/r B-ALL. Early responses at 1 month and OS and EFS at 6 and 12 months are comparable to reported ELIANA trial outcomes. Safety is demonstrated in this cohort with lower rates or CRS and neurotoxicity, likely related to a lower disease burden cohort. Continued relapse and decrease in OS without evident plateau is seen following 6 months post-infusion warranting expanded follow up. Comparative analysis of outcomes in patient cohorts with varying disease burden demonstrate decreased CR, EFS and OS in patients with high disease burden as compared to patients with lower disease burden or no detectable disease at last evaluation prior to CAR infusion. Disclosures Phillips: Novartis: Membership on an entity's Board of Directors or advisory committees. Stefanski:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Margossian:Novartis: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Verneris:Fate Therapeutics: Consultancy, Current equity holder in publicly-traded company; Novartis: Membership on an entity's Board of Directors or advisory committees; Bmogen: Consultancy, Current equity holder in publicly-traded company; Uptodate: Consultancy. Myers:Novartis: Consultancy, Honoraria, Other: ELIANA trial Steering Committee, Speakers Bureau. Brown:Jazz: Honoraria; Servier: Honoraria; Janssen: Consultancy; Novartis: Consultancy. Qayed:Novartis: Consultancy; Mesoblast: Consultancy. Hermiston:Novartis: Membership on an entity's Board of Directors or advisory committees; Sobi: Membership on an entity's Board of Directors or advisory committees. Satwani:Takeda: Consultancy; Mesoblast: Consultancy. Curran:Novartis: Consultancy, Research Funding; Mesoblast: Consultancy; Celgene: Research Funding. Mackall:Lyell Immunopharma: Consultancy, Current equity holder in private company; Nektar Therapeutics: Consultancy; NeoImmune Tech: Consultancy; Apricity Health: Consultancy, Current equity holder in private company; BMS: Consultancy; Allogene: Current equity holder in publicly-traded company. Laetsch:Cellectis: Consultancy; Novartis: Consultancy, Research Funding; Pfizer: Research Funding; Bayer: Consultancy, Research Funding.

Chimeric antigen receptor (CAR) T-cells have transformed the therapeutic options for relapsed/refractory (R/R) B-cell ALL. Data for CAR therapy in extramedullary (EM) involvement is limited. Retrospective data was abstracted from the Pediatric Real World CAR Consortium (PRWCC) of 184 infused patients from 15 US institutions. Response (CR) rate, overall survival (OS), relapse-free survival (RFS), and duration of B-cell aplasia (BCA) in patients referred for tisagenlecleucel with EM disease (both CNS3 and non-CNS EM) were compared to bone marrow (BM) only. Patients with CNS disease were further stratified for comparison. Outcomes are reported on 55 patients with EM disease prior to CAR (n=40 CNS3; n=15 non-CNS EM). The median age at infusion in CNS cohort was 10 years (range &lt;1-25) and the non-CNS EM cohort was 13 years (2-26). In patients with CNS disease, 88% (35/40) achieved a CR, versus only 66% (10/15) with non-CNS EM disease. Patients with CNS disease (both with and without marrow involvement) had comparable 24-month OS outcomes to non-CNS EM or BM only (p=0.41). There was no difference in 12-month RFS between CNS, non-CNS EM, or BM only patients (p=0.92). No increased toxicity was seen with CNS or non-CNS EM disease (p=0.3). Active CNS disease at time of infusion did not impact outcomes. Isolated (iCNS) disease trended towards improved OS when compared to combined CNS and BM (p=0.12). R/R EM disease can be effectively treated with tisagenlecleucel with toxicity, relapse rates and survival rates comparable to patients with BM only. Outcomes for iCNS relapse are encouraging.

Tisagenlecleucel, chimeric antigen receptor T cell (CART) therapy targeting CD19, has shown remarkable complete response (CR) rates for patients up to the age of 26 with refractory/relapsed B-cell acute lymphoblastic leukemia (B-ALL), and is FDA-approved for this indication. Currently, patients receive a single dose of tisagenlecleucel across a wide dose range of 0.2- 5.0 x 106 CAR T cells/kg for patients ≤ 50 kg, or 0.1- 2.5 x 108 CAR T cells for patients &gt; 50 kg. The effect of cell dose on survival and remission has yet to be well-established. Our primary goal was to determine if CART cell dose impacts overall survival (OS), event-free survival (EFS) and relapse-free-survival (RFS) in tisagenlecleucel-recipients. Retrospective data were collected from the Pediatric Real World CAR Consortium (PRWCC) member institutions and included 185 patients infused with commercial tisagenlecleucel. The median dose of viable transduced CAR T cells was 1.7 x106 CAR T cells/kg. To assess the impact of cell dose, we divided the responders into dose quartiles: 0.134-1.300 x 106 (D1; n=48 (27%), 1.301-1.700 x 106 (D2; n=46 (26%), 1.701-2.400 x 106(D3; n=43 (24%) and 2.401-5.100 x 106 (D4; n=43 (24%). OS, EFS, and RFS were improved in patients that received higher doses of Tisagenlecleucel (p=0.031, 0.0079 and 0.0045 respectively). Moreover, higher doses of tisagenlecleucel were not associated with increased toxicity. As the current tisagenlecleucel package insert dose-range remains broad, this work has implications in regard to targeting higher cell doses to optimize patients for long-standing remission.

PURPOSE Nonresponse and relapse after CD19-chimeric antigen receptor (CAR) T-cell therapy continue to challenge survival outcomes. Phase II landmark data from the ELIANA trial demonstrated nonresponse and relapse rates of 14.5% and 28%, respectively, whereas use in the real-world setting showed nonresponse and relapse rates of 15% and 37%. Outcome analyses describing fate after post-CAR nonresponse and relapse remain limited. Here, we aim to establish survival outcomes after nonresponse and both CD19+ and CD19– relapses and explore treatment variables associated with inferior survival. METHODS We conducted a retrospective multi-institutional study of 80 children and young adults with B-cell acute lymphoblastic leukemia experiencing nonresponse (n = 23) or relapse (n = 57) after tisagenlecleucel. We analyze associations between baseline characteristics and these outcomes and establish survival rates and salvage approaches. RESULTS The overall survival (OS) at 12 months was 19% across nonresponders (n = 23; 95% CI, 7 to 50). Ninety-five percent of patients with nonresponse had high preinfusion disease burden. Among 156 morphologic responders, the cumulative incidence of relapse was 37% (95% CI, 30 to 47) at 12 months (CD19+; 21% [15 to 29], CD19–; 16% [11 to 24], median follow-up; 380 days). Across 57 patients experiencing relapse, the OS was 52% (95% CI, 38 to 71) at 12 months after time of relapse. Notably, CD19– relapse was associated with significantly decreased OS as compared with patients who relapsed with conserved CD19 expression (CD19– 12-month OS; 30% [14 to 66], CD19+ 12-month OS; 68% [49 to 92], P = .0068). Inotuzumab, CAR reinfusion, and chemotherapy were used as postrelapse salvage therapy with greatest frequency, yet high variability in treatment sequencing and responses limits efficacy analysis across salvage approaches. CONCLUSION We describe poor survival across patients experiencing nonresponse to tisagenlecleucel. In the post-tisagenlecleucel relapse setting, patients can be salvaged; however, CD19– relapse is distinctly associated with decreased survival outcomes.

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