scholarly journals Therapy of Paediatric B-ALL with a Fast Off Rate CD19 CAR Leads to Enhanced Expansion and Prolonged CAR T Cell Persistence in Patients with Low Bone Marrow Tumour Burden, and Is Associated with a Favourable Toxicity Profile

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 225-225
Author(s):  
Sara Ghorashian ◽  
Anne Marijn Kramer ◽  
Shimobi Onuoha ◽  
Gary Wright ◽  
Jack Luke Bartram ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Magnetic Bead ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Post Infusion ◽  
Grade 3

Introduction: The CARPALL study (NCT02443831) employed a novel CD19CAR (CAT-41BBz CAR) with a faster off rate than the Kymriah FMC63-41BBz CAR (CAT 3.1x10-3s-1, FMC 6.8 x 10-5s-1), with equivalent on-rate (CAT 2.2 x 105, FMC 2.1 x 105). We herein report updated outcomes and CAR T cell persistence with an additional 6 months follow up from a submitted manuscript (Ghorashian et al., Nat Med, submitted) Methods: Patients aged <25 years with high risk, relapsed CD19+ B-ALL were eligible on this multi-centre, open label, non-randomised phase I study of autologous CAT-41BBz CAR T cells. Patients were followed to a data cut-off of 07/18/2019. CAT-41BBz CAR T cells were generated by magnetic bead activation of leucapheresed PBMCs, lentiviral transduction, followed by bioreactor expansion and magnetic bead removal prior to cryopreservation. All patients received lymphodepletion (fludarabine + cyclophosphamide) followed by 1x106/kg CAR T cells. Presence of CAR T cells in the blood and bone marrow (BM) was assessed (flow cytometry and qPCR) monthly for 6 months, then 6 weekly to 1 year and then 3 monthly. BM MRD was assessed (IgH qPCR, flow cytometry) at the same time-points up to 2 years to establish durability of responses as a stand-alone therapy. Primary end-points were incidence of grade 3-5 toxicity and the proportion of patients achieving molecular remission. Results: Of 17 patients recruited, 14 were treated due to manufacturing failure in 3 patients.The median age was 9 years (range 1-19 years). All patients had advanced ALL with a median of 4 prior therapy lines. 10 of 14 patients (71%) had relapsed post allogeneic SCT. Prior to lymphodepletion, 4 patients had >5% BM disease, 6 had disease between 5x10-2and 1x10-5, 4 were BM MRD negative having had recurrent isolated CNS disease. Median transduction efficiency was 31% (range 16.5 to 96.4%). 12/14 treated patients received the anticipated dose of 1x106CAR T cells/kg (2 received 0.9x106/kg). Considering all evaluable patients, (n=14 for CAR T cell persistence by qPCR, n=13 by flow) the geometric mean of Cmax was 128 912/µg DNA and of the area under the curve between D0 and D28 was 1,721,355 copies/ µg DNA (Table 1). At the point of maximal expansion, a median of 35% of circulating T cells were CAR+. Median half-life was 34 days (range 3-102). CAR T cells continued to be detectable by qPCR in 11 of 14 (79%) patients at last assessment and by flow cytometry up to 30 months post infusion in 8 of 13(61%). Median duration of CAR T persistence by flow was 261 days (range 7-917). 3 patients failed to have persistence of CAR T cells beyond 1 month. T cell mediated anti-CAR specific cytotoxic activity was detected in 2/2 evaluable patients. Updated persistence data will be presented at the meeting Cytokine release syndrome (CRS) occurred in 13 (93%, grade 1 n=9, grade 2 n=4). None developed ≥grade 3 CRS, had CRS-related ICU admission, or received Tocilizumab. CRS was associated with modest elevations of IL-6, IFN-γand IL-10. Grade 2 neurotoxicity was observed in 3 patients and resolved spontaneously. One patient had grade 4 leucoencephalopathy presumed due to chemotherapy as well as grade 5 sepsis. Ten patients (71%) had grade 3-4 cytopenia persisting beyond day 28 or recurring afterthis. 12/14 (86%) patients achieved molecular complete or continuing complete remission at a median of 30 days post infusion (range 30-90 days, Table 2). At a median follow-up of 20.3 months, 4/14 (29%) evaluable patients remain MRD negative. 5 relapsed with CD19-disease, 1 with CD19+ disease. The median duration of EFS (based on death or morphological relapse) has not been reached, 12 month EFS = 52%, OS = 70% (Figures 1, 2 and Table 3). Conclusion: We noted excellent CAR T cell expansion and persistence in a ALL cohort treated with the fast off-rate CAT-41BBz CAR despite their lower BM disease at treatment compared to other studies. The kinetics documented for all evaluable patients showed a 5-fold greater CAR T cell expansion and 2-fold longer half-life than responders in published series utilising tisagenlecleucel in a similar ALL cohort (Mueller et al., Blood 2017). Patients had a favourable toxicity profile with no severe (grade 3-4) CRS and equivalent disease outcomes to the ELIANA study despite having similarly advanced disease (Maude et al., NEJM 2018292). These data suggest long lived CAR T cell persistence supports stand-alone therapy for ALL with durable responses. Disclosures Ghorashian: Celgene: Honoraria; novartis: Honoraria; UCLB: Patents & Royalties: UCLB. Kramer:UCLB: Patents & Royalties. Ciocarlie:Servier: Other: Financial Support. Farzaneh:Autolus Ltd: Equity Ownership, Research Funding. Pule:Autolus: Employment, Equity Ownership, Patents & Royalties. Amrolia:UCLB: Patents & Royalties.

scholarly journals A Novel Low Affinity CD19CAR Results in Durable Disease Remissions and Prolonged CAR T Cell Persistence without Severe CRS or Neurotoxicity in Patients with Paediatric ALL

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 806-806
Author(s):  
Sara Ghorashian ◽  
Anne Marijn Kramer ◽  
Sarah Jayne Albon ◽  
Gary Wright ◽  
Fernanda Castro ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Transduction Efficiency ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Post Infusion ◽  
Grade 3

Abstract Introduction: Published studies of CD19 CAR T cells have shown unprecedented response rates in ALL but with a 23-27% incidence of severe Cytokine Release Syndrome (CRS) and 27-50% incidence of severe neurotoxicity which may limit broader application. We developed a novel second generation CD19CAR (CAT-41BBz CAR) with a lower affinity and faster off-rate but equivalent on-rate than the FMC63-41BBz CAR (Kd 116 nM vs 0.9 nM, T1/2 10s vs 1260s) utilised in CTL019 currently under consideration by the FDA. Pre-clinical studies indicated T-cells transduced with CAT-41BBz mediate enhanced tumor clearance and show increased expansion in an NSG-NALM6 stress test model (Kramer et al., submitted). We here report interim results from a multi-centre, Phase I clinical study of autologous CAT-41BBz CAR T cells as therapy for high risk/relapsed paediatric ALL, CARPALL (NCT02443831) demonstrating efficacy with an excellent safety profile. Methods: Autologous T cells were activated with anti-CD3/CD28 beads, transduced with a SIN lentiviral vector encoding CAT-41BBz CAR and expanded for 4 days prior to magnetic bead removal and cryopreservation. Transduction efficiency was assessed using an anti-idiotype antibody. Serum levels of cytokines associated with CRS were measured using cytometric bead array. All patients received lymphodepletion with fludarabine 150 mg/m2 + cyclophosphamide 1.5g/m2 followed by a single infusion of CAR T cells at a dose of 1x106 CAR+ T cells. Patients were monitored for the presence of CAR T cells in the blood by flow cytometry and by qPCR for the 41BBz junctional region, as well as circulating B cell count monthly for 6 months and then 6 weekly to 1 year. Disease status was assessed in the bone marrow morphologically, by IgH qPCR, as well as by flow cytometric assessment of MRD at the same time-points to establish durability of responses as a stand-alone therapy. The primary end-points were incidence of grade 3-5 toxicity related to CAR T cells within 30 days and the proportion of patients achieving molecular remission. Results: We have enrolled 10 patients and treated 8 to date. Six of 8 had relapsed post myeloablative SCT. The median disease burden prior to lymphodepletion was 9% blasts (ranging from molecular CR to 74% blasts, Table 1). It was possible to generate a product meeting release criteria in all but 1 patient (90% feasibility). Median transduction efficiency was 18.1% (range 6.7 to 76.3%). All treated patients received the anticipated dose of 1x106 CAR T cells/kg. Cytokine release syndrome occurred in all patients (grade 1 n=4, grade 2 n=4), but to date none have developed ≥ grade 3 CRS, required ICU admission or therapy with Tocilizumab. CRS was associated with modest elevations of IL-6, IFN-γ and IL-10 and resolved spontaneously in all. Grade 2 neurotoxicity was observed in 3 patients and resolved spontaneously, but no severe (≥grade 3) neurotoxicity was seen. Five patients had prolonged grade 4 neutropenia lasting > 30 days but this resolved in all by 2 months. Only 1 patient experienced significant infective complications in the context of pre-existing poor marrow reserve following allogeneic SCT. 6/7 (86%) evaluable patients achieved molecular remission at a median of 30 days post infusion (range 30-60 days, Table 1). One patient did not respond and died of CD19+ disease progression. At a median follow-up of 5.9 months (range 28-328 days), 4/7 evaluable patients remain in flow MRD negative remission of whom 3 show no evidence of molecular MRD at 1, 7.5 and 9 months. Two patients relapsed with CD19- disease at 3 and 4 months post infusion: 1 of these remains alive with disease at 11 months and the other died of disease progression. Reflecting our pre-clinical data with CAT-41BBz CAR, we have seen excellent CAR T cell expansion (median 65459 copies/µg DNA at 1 month, range 609 to 230112) and persistence at up to 11 months post-infusion (Figure 1). All 7 evaluable patients have ongoing CAR T cell persistence detectable by both flow and qPCR as well as ongoing B cell aplasia at last follow-up. Conclusions: These interim results with a novel low affinity CD19 CAR show similar remission rates to those reported by US studies in paediatric ALL with an improved safety profile. No severe (grade ≥3) CRS or neurotoxicity has occurred to date despite high tumour burden in 4 patients. Excellent CAR T cell expansion has been documented, as well as long duration of CAR T cell persistence and associated B cell aplasia. Disclosures Ghorashian: UCL: Patents & Royalties: UCL Business. Kramer: UCL: Patents & Royalties: UCL Business. Lucchini: Alexion: Membership on an entity's Board of Directors or advisory committees. Pule: Autolus Ltd: Employment, Equity Ownership, Research Funding; UCL: Patents & Royalties: UCL Business.

scholarly journals Feasibility, and Efficacy of Donor-Derived cd19-Targeted Car t-Cell Therapy in Refractory/Relapsed(r/r)b-Cell Acute Lymphoblastic Leukemia (b-all) Patients

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 4-6
Author(s):  
Xian Zhang ◽  
Junfang Yang ◽  
Wenqian Li ◽  
Gailing Zhang ◽  
Yunchao Su ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T ◽  
Grade 3

Backgrounds As CAR T-cell therapy is a highly personalized therapy, process of generating autologous CAR-T cells for each patient is complex and can still be problematic, particularly for heavily pre-treated patients and patients with significant leukemia burden. Here, we analyzed the feasibility and efficacy in 37 patients with refractory/relapsed (R/R) B-ALL who received CAR T-cells derived from related donors. Patients and Methods From April 2017 to May 2020, 37 R/R B-ALL patients with a median age of 19 years (3-61 years), were treated with second-generation CD19 CAR-T cells derived from donors. The data was aggregated from three clinical trials (www.clinicaltrials.gov NCT03173417; NCT02546739; and www.chictr.org.cn ChiCTR-ONC-17012829). Of the 37 patients, 28 were relapsed following allogenic hematopoietic stem cell transplant (allo-HSCT) and whose lymphocytes were collected from their transplant donors (3 HLA matched sibling and 25 haploidentical). For the remaining 9 patients without prior transplant, the lymphocytes were collected from HLA identical sibling donors (n=5) or haploidentical donors (n=4) because CAR-T cells manufacture from patient samples either failed (n=5) or blasts in peripheral blood were too high (>40%) to collect quality T-cells. The median CAR-T cell dose infused was 3×105/kg (1-30×105/kg). Results For the 28 patients who relapsed after prior allo-HSCT, 27 (96.4%) achieved CR within 30 days post CAR T-cell infusion, of which 25 (89.3%) were minimal residual disease (MRD) negative. Within one month following CAR T-cell therapy, graft-versus-host disease (GVHD) occurred in 3 patients including 1 with rash and 2 with diarrhea. A total of 19 of the 28 (67.9%) patients had cytokine release syndrome (CRS), including two patients (7.1%) with Grade 3-4 CRS. Four patients had CAR T-cell related neurotoxicity including 3 with Grade 3-4 events. With a medium follow up of 103 days (1-669days), the median overall survival (OS) was 169 days (1-668 days), and the median leukemia-free survival (LFS) was 158 days (1-438 days). After CAR T-cell therapy, 15 patients bridged into a second allo-HSCT and one of 15 patients (6.7%) relapsed following transplant, and two died from infection. There were 11 patients that did not receive a second transplantation, of which three patients (27.3%) relapsed, and four parents died (one due to relapse, one from arrhythmia and two from GVHD/infection). Two patients were lost to follow-up. The remaining nine patients had no prior transplantation. At the time of T-cell collection, the median bone marrow blasts were 90% (range: 18.5%-98.5%), and the median peripheral blood blasts were 10% (range: 0-70%). CR rate within 30 days post CAR-T was 44.4% (4/9 cases). Six patients developed CRS, including four with Grade 3 CRS. Only one patient had Grade 3 neurotoxicity. No GVHD occurred following CAR T-cell therapy. Among the nine patients, five were treated with CAR T-cells derived from HLA-identical sibling donors and three of those five patients achieved CR. One patient who achieved a CR died from disseminated intravascular coagulation (DIC) on day 16. Two patients who achieved a CR bridged into allo-HSCT, including one patient who relapsed and died. One of two patients who did not response to CAR T-cell therapy died from leukemia. Four of the nine patients were treated with CAR T-cells derived from haploidentical related donors. One of the four cases achieved a CR but died from infection on day 90. The other three patients who had no response to CAR T-cell therapy died from disease progression within 3 months (7-90 days). Altogether, seven of the nine patients died with a median time of 19 days (7-505 days). Conclusions We find that manufacturing CD19+ CAR-T cells derived from donors is feasible. For patients who relapse following allo-HSCT, the transplant donor derived CAR-T cells are safe and effective with a CR rate as high as 96.4%. If a patient did not have GVHD prior to CAR T-cell therapy, the incidence of GVHD following CAR T-cell was low. Among patients without a history of transplantation, an inability to collect autologous lymphocytes signaled that the patient's condition had already reached a very advanced stage. However, CAR T-cells derived from HLA identical siblings can still be considered in our experience, no GVHD occurred in these patients. But the efficacy of CAR T-cells from haploidentical donors was very poor. Disclosures No relevant conflicts of interest to declare.

scholarly journals Evolution and Proliferation of CD7 CAR-T Cells Compared to CD19 CAR-T Cells Therapies for Acute Leukemia

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2820-2820
Author(s):  
Xian Zhang ◽  
Gailing Zhang ◽  
Wenqian Li ◽  
Liyuan Qiu ◽  
Dongchu Wang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Body Temperature ◽  
Incidence Rate ◽  
Cell Ratio ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Grade 3

Abstract Background In October 2020, we began the clinical trials of CD7 CAR-T treatment for CD7-positive hematological malignancies at our center. We found that the proliferation profile and evolution of CD7 CAR-T cells within 1-month following infusion into patients were quite different from those of CD19 CAR-T cells. From these data, we reasoned that the time to occurrence of CAR-T-cell-related side effects might also differ between the two cellular therapies. Here, we systematically compared the proliferation and CAR-T-cell-related side effects of CD7 CAR-T cells to these of CD19 CAR-T cells. Patients and Methods From October 2020 to June 2021, a total of 30 patients (24 male, 6 female) including 22 with T-cell acute lymphoblastic leukemia (T-ALL), 3 with T-cell lymphoblastic lymphoma (T-LBL), and 5 with mixed phenotype acute leukemia (MPAL) received autologous CD7 CAR-T cells manufactured by the SenlangBio company (https://clinicaltrials.gov NCT04572308, NCT04796441 and NCT04938115). The median follow-up time was 116 days (range: 15-221days). On Day 30, 25/30 patients (83.3%) achieved complete remission (CR)/CR with incomplete blood recovery (CRi). From December 2017 to June 2021, 45 B-ALL patients (19 male, 26 female) received CD19 CAR-T cells, also manufactured by SenlangBio (NCT04792593 and NCT04546893). The median follow-up time was 351 days (range: 15-1110days). On Day 30, 43/45 patients (95.6%) achieved CR/CRi. The median infused CD7 CAR-T cell dose was 1×10 6/kg (range: 0.5-2×10 6/kg), and the median infused CD19 CAR-T cell dose was 3×10 5/kg (range: 0.2-10×10 5/kg). The CD7 or CD19 CAR-T cell ratio in peripheral blood lymphocytes (PBLC) and the CD7 or CD19 B-lymphocyte percentage in PBLC samples from patients were analyzed on days 0, 4, 7, 10, 14, 21, and 30 following CAR-T cell infusion using flow cytometry. Results The presence of CD7 CAR-T cells in the PBLC samples were gradually detected following CD7 CAR-T cell infusion. The CD7 CAR-T cell ratio in PBLC increased significantly on Day 10. CD7 CAR-T cell peak appeared on Day 21 with a peak of 39.14% (range: 0.04%-74.58%), and was still detectable on Day 30 with a high CD7 CAR-T ratio of 7.5% (1.15%-70.41%). The ratio of CD19 CAR-T cells in patient PBLC samples showed a significant increase on Day 7 following infusion, and the CAR-T cell peak appeared on Day 10 with a peak of 14.71% (range: 0.11%-89.33%), and then quickly decreased to 0.23% (range: 0%-82.88%) on Day 21 (Figure 1). As the CAR-T cells increased, the proportion of target cells decreases significantly (Figure 2). However, the rate of decrease of CD19 cells differed from that of CD7 cells. CAR-T cell proliferation is also associated with CAR-T-cell-related adverse effects including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Observing the adverse effects after CD7 CAR-T infusion, we found that fever (incidence rate of 83.8%) occurred on the first 1-3 days following infusion, with a body temperature among patients of about 38°C. After patients' body temperature dropped to approximately normal levels, fever occurred again on Day 10-21 (incidence rate of 77.4%), and a higher temperature of 38-40°C was observed. The adverse event profile coincided with the proliferation of CD7 CAR-T cells we observed. Among the 30 cases, 5 had Grade 2 CRS, 2 had CRS of Grade ≥3, and 1 patient had Grade 3 ICANS. Fever following CD19 CAR-T infusion consisted mainly on Day 7-14 after the infusion (incidence rate of 86.6%), followed by a gradual drop of body temperature to normal after Day 14. Among the 45 patients, 5 had Grade 2 CRS, 5 had CRS of Grade ≥3 and 7 had Grade ≥3 ICANS. Conclusions In this clinical study, we found that the proliferation and evolution of CD7 CAR-T cells are distinct from that of C19 CAR-T cells. CD7 CAR-T cells began to proliferate significantly later following patient infusion and persisted longer compared to CD19 CAR-T cells. We found that patients experienced two rounds of fever, appearing on Day 1-3 and Day 10-21 following CD7 CAR-T infusion, which required more attention and prevention compared to the fever experienced by patients infused with CD19 CAR-T cells. However, the incidence of CRS and ICANS did not increase following CD7 CAR-T infusion. More patients and long-term observation are needed to confirm these results and to improve clinical management of patients treated with CAR-T cellular therapies. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals AUTO1, a Novel Fast Off CD19CAR Delivers Durable Remissions and Prolonged CAR T Cell Persistence with Low CRS or Neurotoxicity in Adult ALL

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 226-226 ◽  
Author(s):  
Claire Roddie ◽  
Maeve A O'Reilly ◽  
Maria A V Marzolini ◽  
Leigh Wood ◽  
Juliana Dias Alves Pinto ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Board Of Directors ◽  
Advisory Committees ◽  
Split Dose ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Grade 3

Introduction: In adults, prognosis for B-ALL is poor, patients are more vulnerable to CD19 CAR immunotoxicity and there is currently no CD19 CAR therapeutic with acceptable toxicity and durable efficacy. We have developed a novel second generation CD19CAR (CAT-41BBz CAR), with a faster off-rate but equivalent on rate than the FMC63-41BBz CAR (Kd 116 nM vs 0.9 nM, T1/2 9s vs 4.2 hours) designed to result in more physiological T-cell activation, reduce toxicity and improve engraftment. Preliminary paediatric clinical data of this novel CD19 CAR (AUTO1) supports this assertion. We here describe preliminary data from ALLCAR19 (NCT02935257), a multi-centre, Phase I clinical study of AUTO1 as therapy for r/r adult B-ALL. Methods: Manufacturing: AUTO1 utilises non-mobilised autologous leucapheresate. The first 6 trial products were generated using a standard dynal bead/WAVE Bioreactor process and subsequent products using a semi-automated closed process. Study design: ALLCAR19 is a phase I/II study recruiting subjects 16-65y with r/r B ALL. Lymphodepletion with fludarabine (30mg/m2 x3) and cyclophosphamide (60mg/kg x1) is followed by split dose CAR T cell infusion (Day 0: if ≥20% BM blasts, infuse 10 x 106 CAR T cells ; if <20% BM blasts, infuse 100 x 106 CAR T cells. Day +9: if no Grade 3-5 CRS/CRES, infuse Dose 2, to a total dose of 410 x 106 CAR T cells). Study endpoints include feasibility of manufacture, grade 3-5 toxicity and remission rates at 1 and 3 months Results: As of 24 July 2019, 16 patients have been leukaphresed, 14 products manufactured (one failed leukaphresis and one currently in manufacture) and 13 patients have received at least 1 dose of AUTO1. Of the 16 patients, median age was 35.5 (range 18-63), 10/16 (63%) had prior blinatumomab or inotuzumab ozogamicin and 12/16 (75%) had prior HSCT. At the time of pre-conditioning, 9/13 (69%) patients were in morphological relapse with >5% leukemic blasts of which 6/13 (46%) had ≥50% blast. 9/13 patients (69%) received the total target split dose of 410 x 106 CAR T cells while 1/13 patients (8%) received a reduced split total dose of 51.3 x 106 CAR T cells due to manufacturing constraints. 3/13 patients (23%) received only a first dose of 10 x 106 CAR T cells. The dose was administered safely to date: No patients experienced ≥Grade 3 CRS (using Lee criteria) and only 1/13 (8%) experienced Grade 3 neurotoxicity (dysphasia) that resolved swiftly with steroids. All patients had robust CAR expansion (median peak expansion 172 CAR/uL blood). Of the 13 patients dosed (1/13 pending 28 day follow up), 10/12 (83%) achieved MRD negative CR at 1 month and all patients had ongoing CAR T cell persistence at last follow up. Two patients experienced CD19 negative relapse (one at M3, one at M6), 1 patient died on D17 before first response evaluation, 1 died in molecular CR from sepsis, and 1 died from persistent disease. Currently, 7/12 remain on study and continue in flow/molecular MRD negative remission with a median follow up of 9.0 months (range 1.2-14.8). Conclusions: AUTO1 delivers excellent early remission rates with initial data showing 83% MRD negative CR and robust CAR expansion and persistence. Despite high tumour burden, the safety profile compares favourably to other CD19 CARs, with no cases of severe CRS and only one case of Gr3 neurotoxicity. This is consistent with experience in the paediatric cohort. Updated results will be presented. Disclosures Roddie: Novartis: Consultancy; Gilead: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau. O'Reilly:Kite Gilead: Honoraria. Farzaneh:Autolus Ltd: Equity Ownership, Research Funding. Linch:Autolus: Membership on an entity's Board of Directors or advisory committees. Pule:Autolus: Membership on an entity's Board of Directors or advisory committees. Peggs:Gilead: Consultancy, Speakers Bureau; Autolus: Membership on an entity's Board of Directors or advisory committees.

Interim analysis of ZUMA-5: A phase II study of axicabtagene ciloleucel (axi-cel) in patients (pts) with relapsed/refractory indolent non-Hodgkin lymphoma (R/R iNHL).

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 8008-8008 ◽  
Author(s):  
Caron A. Jacobson ◽  
Julio C. Chavez ◽  
Alison R. Sehgal ◽  
Basem M. William ◽  
Javier Munoz ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Objective Response ◽  
Blood Levels ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Grade 3 ◽  
Anti Cd20

8008 Background: Advanced stage iNHL, including follicular lymphoma (FL) and marginal zone lymphoma (MZL), is considered incurable as most pts experience multiple relapses (Wang, et al. Ther Adv Hematol. 2017), highlighting a need for novel therapies. Here, we present interim results from ZUMA-5, a Phase 2, multicenter study of axi-cel, an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy, in pts with R/R iNHL. Methods: Adults with R/R FL (Grades 1-3a) or MZL (nodal or extranodal) after ≥ 2 lines of therapy (including an anti-CD20 monoclonal antibody [mAb] with an alkylating agent), and an ECOG of 0 – 1 were eligible. Pts were leukapheresed and received conditioning chemotherapy followed by axi-cel infusion at 2 × 106 CAR T cells/kg. The primary endpoint was objective response rate (ORR) by central review (Cheson, et al. J Clin Oncol. 2014). Secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), safety, and blood levels of cytokines and CAR T cells. Results: As of 8/20/19, 94 pts (80 FL; 14 MZL) received axi-cel with a median follow-up of 11.5 mo (range, 4.2 – 24.9). Median age was 63 y (range, 34 – 79), 47% of pts were male, 52% had stage IV disease, 51% had ≥ 3 FLIPI, and 59% had high tumor bulk (GELF). Pts had a median 3 prior lines of therapy, 66% progressed < 2 y after initial anti-CD20 mAb-containing therapy (POD24), and 73% were refractory to the last prior treatment. Of 87 pts evaluable for efficacy, ORR was 94% (79% complete response [CR] rate). Pts with FL (n = 80) had an ORR of 95% (80% CR rate). Pts with MZL (n = 7) had an ORR of 86% (71% CR rate). Overall, 68% of pts had ongoing responses as of the data cutoff. Updated data, including DOR, PFS, and OS with longer follow-up, will be included in the presentation. Of 94 pts evaluable for safety, 83% experienced Grade ≥ 3 adverse events (AEs), most commonly neutropenia (33%) and anemia (28%). Grade ≥ 3 cytokine release syndrome (CRS; per Lee et al, Blood 2014) and neurologic events (NEs; per CTCAE v4.03) occurred in 11% and 19% of pts, respectively. Median times to onset of CRS and NEs were 4 and 7 d, with median durations of 6 and 14.5 d. There were 2 Grade 5 AEs: multisystem organ failure in the context of CRS (related to axi-cel) and aortic dissection (unrelated to axi-cel). Median peak and AUC0-28 CAR T cell levels were 44 cells/µL and 490 cells/µL × d, respectively. Conclusions: Axi-cel demonstrated significant and durable clinical benefit, with high rates of ORR and CR, and a manageable safety profile in pts with R/R iNHL. Clinical trial information: NCT03105336 .

scholarly journals Feasibility of Outpatient CAR T Cell Therapy: Experience of a Single Institution

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4828-4828
Author(s):  
Yusra F Shao ◽  
Dipenkumar Modi ◽  
Andrew Kin ◽  
Asif Alavi ◽  
Lois Ayash ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T ◽  
Grade 3

Abstract Background Chimeric Antigen Receptor (CAR) T cell therapy has emerged as a promising therapeutic option for relapsed/refractory non-Hodgkin lymphoma. However, access to CAR T cell therapy remains limited as CAR T cells are routinely administered in the hospital setting. Hence, there's a growing interest in standardizing outpatient administration of CAR T cells to increase patient access and minimize costs. Here, we describe our institution's experience with outpatient administration of CAR T cells. Methods In this retrospective study, we reviewed who received CAR T cell therapy in the outpatient setting at Karmanos Cancer Center between June 2019 and June 2021.Charts were reviewed for age, disease pathology, prior lines of therapy, need for hospitalization within 30 days, development of CRS and/or neurotoxicity, need for ICU admission, need for steroids and/or tocilizumab, length of admission, and disease state at last follow up. All patients received fludarabine and cyclophosphamide as lymphodepletion (LD) therapy day -5 to -3. CAR T cells were infused on day 0. Patients subsequently followed up in clinic daily for 2 weeks and were started on allopurinol, ciprofloxacin, fluconazole, acyclovir and levetiracetam. First response was assessed by FDG PET scan 4 weeks after CAR T cell . Results A total of 12 patients received CAR T cells during the study period. All patients had a diagnosis of DLBCL and received Tisagenlecleucel. Median age at CAR T cell therapy was 69.5 years (40-78 years). Median number of prior lines of therapy was (2-3) while 2 patients had received prior stem cell transplantation. Table 1 describes patient characteristics and lines of therapy. Two patients received bridging therapy prior to LD. Overall response rate was 58.3% (complete response-3, partial response-4). Median duration of follow up was 6.7 (0.6-13.8 months). Four patients required subsequent therapy after CAR T cell for disease progression while 9 patients were alive at the time of data cut off. Figure 1 summarizes disease response and follow . Table 2 summarizes complications during follow up. Nine (75%) patients developed anemia (grade 3-4 n=4, 33.3%), 8 (66.7%) developed thrombocytopenia (grade 3-4 n= 3, 37.5%), and 8 (66.7%) developed neutropenia (grade 3-4 n=8, 66.7%). Median time to platelet recovery to &gt;,000 and neutrophil recovery to &gt;500 was 66 days (44-81 days) and 11.5 days (6-65 days), respectively. Three (25%) patients required platelet and red blood cell transfusion support. Six (50%) patients developed cytokine release syndrome (CRS) with median grade 2 (range 1-3, grade 3-4 n=1). Five (5/6) patients required hospitalization, five (5/6) required tocilizumab, and one (1/6) required steroids. One (8.3%) patient developed neurotoxicity of grade 1 severity improved without systemic therapy. Six patients required hospitalization within 30 days of CAR T cell infusion. Median day of admission from CAR T cell infusion was 4 days (range 2-12 days (range 2-12 days, admission within 3 days n=2, admission under observation n=1). Patient characteristics at admission are summarized in table 3. Of these, 5 patients were diagnosed with CRS,1 patient with colitis and none with blood stream infection. Two patients required ICU admission. Median length of hospital admission was 5.5 days (2-9 days). All patients were alive at discharge while 1 patient required subsequent admission within 30 . Conclusion Outpatient administration of Tisagenlecleucel is feasible with low risk of hospital admission within 3 days of infusion. Adoption of outpatient CAR T cell therapy may increase patient access for treatment of DLBCL and diseases such as multiple myeloma while reducing administration costs for this novel therapy. Figure 1 Figure 1. Disclosures Modi: Genentech: Research Funding; Seagen: Membership on an entity's Board of Directors or advisory committees; MorphoSys: Membership on an entity's Board of Directors or advisory committees. Deol: Kite, a Gilead Company: Consultancy.

scholarly journals A Feasibility and Safety Study of CD19 and CD22 Chimeric Antigen Receptors-Modified T Cell Cocktail for Therapy of B Cell Acute Lymphoblastic Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 277-277 ◽  
Author(s):  
Junfang Yang ◽  
Jianqiang Li ◽  
Xian Zhang ◽  
Fanyong LV ◽  
Xiaoling Guo ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Lymphoblastic Leukemia ◽  
Median Number ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Post Infusion

Abstract Introduction: Chimeric antigen receptor (CAR) T cell therapy targeting CD19 has recently demonstrated high success but also shown limitations regarding their toxicity and development of CD19negative variants. Here we reported results from a phase I study designed to determine the safety of the CD19 CAR-T and CD22 CAR-T cocktail and the feasibility of making enough quantities to treat patients with CD19+CD22+ relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL). Patients and Methods: From July 2017 to July 2018, a total of 15 patients with CD19+CD22+ relapsed/refractory B-ALL were treated, including 5 children and 10 adults (Table 1). All patients received fludarabine 30mg/m2/d´3d and cyclophosphamide 250mg/m2/d´2d before infusion of CAR-T cells, followed by a cocktail CAR-T cell infusion with a median number of 2 (0.9-5)´105 CD19 CAR+ T cells/kg and a median number of 0.5 (0.4-12)´105 CD22 CAR+ T cells/kg. The lentiviral backbone containing constructs of CD19 CAR and CD22 CAR are shown in Figure 1. CD19 CAR includes a truncated EGFR sequence which can be used to identify and select CAR+ cells. CD22 CAR includes a single chain variable fragment (ScFv) sequence derived from a monoclonal antibody against human PD-L1 which attempts to reduce the exhaustion of CAR-T cells by blocking the PD-1/PD-L1. Real-time quantitative PCR using primers with specificity for the ScFv of CD19 CAR and ScFv of CD22 CAR can detect the in vivo CAR-T persistence for either CAR. Sequential transduction was performed 2 days after activation of sorted T cells stimulated with CD3 and CD28 antibodies. Percentages of CD19 CAR+ and CD22 CAR+ T cells were determined by flow cytometry through staining with an antibody against EGFR and a fusion protein of CD22-Fc, respectively, and expression of anti-PDL1 ScFv in CD22 CAR-T cells were demonstrated by flow cytometry through intracellular staining with a PD-L1-Fc fusion protein. The primary end points of this study were to evaluate feasibility and toxicity, and the secondary end points included disease response and persistent CAR-T engraftment of infused CAR-T cell. Results: The median observation period was 133 days (24-392 days). The median percentage of pre-treatment bone marrow CD19+CD22+ blasts was 21.5%(0.11-74.1%). On day 20-30 after CAR-T infusion, 15/15 (100%) cases achieved complete remission (CR) or incomplete CR(CRi), 14/15 (93.3%) cases had negative minimal residual disease (MRD). Patient P098 had residual (0.58%) CD19+CD22+ BM blasts at day 30 post-infusion and thereafter achieved negative MRD after re-infusion with CD19 CAR-T cells. 11/17 patients were bridged into allo-HSCT and have remained in remission state with a median follow up of 133 (97-214) days. 2/5 patients without bridging allo-HSCT relapsed on day 240 and day 105 post-infusion, respectively. Notably, both patients (100%) relapsed with CD19+CD22+ leukemia cells. Despite achievement of a very high CR rate, a very low treatment-related toxicity was observed in this trial. Only 1 patients experienced grade 3 cytokine release syndrome (CRS) and another patient (6.7%) developed grade 3 central nervous system (CNS) toxicity; all other patients were CRS grade<2 and CNS grade 0. On days -1, 1, 4, 7, 10, 14, 21 and 28 after infusion, peripheral blood (PB) was drawn and the level of infused CD19 and CD22 CAR-T cells were analyzed by either qPCR or flow cytometry assay. Results demonstrated obvious in vivo proliferation of both CD19 and CD22 CAR-T cells. The median peak level was 3.5 (0.47-79.1)´104 copy number/mg PB genomic DNA for CD19 CAR-T, and 0.9 (0.08-80.8)´104 copy number/mg PB genomic DNA for CD22 CAR-T. The median day to reach the peak value was day 10 for both CARs, ranging mostly from day 7 to day 14. Conclusion: This study demonstrates technical feasibility, high efficacy and low toxicities of CD19 and CD22 CAR-T cocktail in treating patients with CD19+CD22+ relapsed/refractory B-ALL. Both patients relapsed with CD19+ leukemia suggests this cocktail treatment may reduce the risk of CD19 negative relapse. Low toxicities may relate with small number of infused CAR-T, but involvement of anti-PDL1 ScFv which is co-expressed with CD22 CAR construct cannot be excluded. Therefore, related mechanisms are currently being investigated in the lab. Disclosures No relevant conflicts of interest to declare.

109 Dominant-negative TGFβ receptor 2 enhances GPC3-targeting CAR-T cell efficacy against hepatocellular carcinoma

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A121-A121
Author(s):  
Nina Chu ◽  
Michael Overstreet ◽  
Ryan Gilbreth ◽  
Lori Clarke ◽  
Christina Gesse ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Dominant Negative ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

BackgroundChimeric antigen receptors (CARs) are engineered synthetic receptors that reprogram T cell specificity and function against a given antigen. Autologous CAR-T cell therapy has demonstrated potent efficacy against various hematological malignancies, but has yielded limited success against solid cancers. MEDI7028 is a CAR that targets oncofetal antigen glypican-3 (GPC3), which is expressed in 70–90% of hepatocellular carcinoma (HCC), but not in normal liver tissue. Transforming growth factor β (TGFβ) secretion is increased in advanced HCC, which creates an immunosuppressive milieu and facilitates cancer progression and poor prognosis. We tested whether the anti-tumor efficacy of a GPC3 CAR-T can be enhanced with the co-expression of dominant-negative TGFβRII (TGFβRIIDN).MethodsPrimary human T cells were lentivirally transduced to express GPC3 CAR both with and without TGFβRIIDN. Western blot and flow cytometry were performed on purified CAR-T cells to assess modulation of pathways and immune phenotypes driven by TGFβ in vitro. A xenograft model of human HCC cell line overexpressing TGFβ in immunodeficient mice was used to investigate the in vivo efficacy of TGFβRIIDN armored and unarmored CAR-T. Tumor infiltrating lymphocyte populations were analyzed by flow cytometry while serum cytokine levels were quantified with ELISA.ResultsArmoring GPC3 CAR-T with TGFβRIIDN nearly abolished phospho-SMAD2/3 expression upon exposure to recombinant human TGFβ in vitro, indicating that the TGFβ signaling axis was successfully blocked by expression of the dominant-negative receptor. Additionally, expression of TGFβRIIDN suppressed TGFβ-driven CD103 upregulation, further demonstrating attenuation of the pathway by this armoring strategy. In vivo, the TGFβRIIDN armored CAR-T achieved superior tumor regression and delayed tumor regrowth compared to the unarmored CAR-T. The armored CAR-T cells infiltrated HCC tumors more abundantly than their unarmored counterparts, and were phenotypically less exhausted and less differentiated. In line with these observations, we detected significantly more interferon gamma (IFNγ) at peak response and decreased alpha-fetoprotein in the serum of mice treated with armored cells compared to mice receiving unarmored CAR-T, demonstrating in vivo functional superiority of TGFβRIIDN armored CAR-T therapy.ConclusionsArmoring GPC3 CAR-T with TGFβRIIDN abrogates the signaling of TGFβ in vitro and enhances the anti-tumor efficacy of GPC3 CAR-T against TGFβ-expressing HCC tumors in vivo, proving TGFβRIIDN to be an effective armoring strategy against TGFβ-expressing solid malignancies in preclinical models.Ethics ApprovalThe study was approved by AstraZeneca’s Ethics Board and Institutional Animal Care and Use Committee (IACUC).

scholarly journals P08.05 Combined pharmacological targeting of adenosine 2a- and 2b-receptor enhances CAR T cell function

2021 ◽  
Vol 9 (Suppl 1) ◽  
pp. A26.2-A27
Author(s):  
M Seifert ◽  
M Benmebarek ◽  
B Cadilha ◽  
J Jobst ◽  
J Dörr ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Combination Therapy ◽  
Cell Function ◽  
Cytokine Secretion ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Cell Effector

BackgroundDespite remarkable response rates mediated by anti-CD19 chimeric antigen receptor (CAR) T cells in selected B cell malignancies, CAR T cell therapy still lacks efficacy in the vast majority of tumors. A substantial limiting factor of CAR T cell function is the immunosuppressive tumor microenvironment. Among other mechanisms, the accumulation of adenosine within the tumor can contribute to disease progression by suppressing anti-tumor immune responses. Adenosine 2a- and 2b-receptor (A2A and A2B)-mediated cAMP build-up suppresses T cell effector functions. In the present study we hypothesize, that combination therapy with the selective A2A/A2B dual antagonist AB928 (etrumadenant) enhances CAR T cell efficacy.Materials and MethodsSecond generation murine (anti-EPCAM) and human (anti-MSLN) CAR constructs, containing intracellular CD28 and CD3ζ domains, were fused via overlap extension PCR cloning. Murine or human T cells were retrovirally transduced to stably express the CAR constructs. A2A/A2B signaling in CAR T cells was analyzed by phospho-specific flow cytometry of CREB (pS133)/ATF-1 (pS63). CAR T cell activation was quantified by flow cytometry and enzyme-linked immunosorbent assay (ELISA) of IFN-γ, IL-2 and TNF-α. CAR T cell proliferation was assessed by flow cytometry. CAR T cell cytotoxicity was assessed by impedance based real-time cell analysis.ResultsAB928 protected murine CAR T cells from cAMP response element-binding protein (CREB) phosphorylation in the presence of stable adenosine analogue 5′-N-ethylcarboxamidoadenosine (NECA). NECA inhibited antigen-dependent CAR T cell cytokine secretion in response to four murine tumor cell lines. CAR T cell-mediated tumor cell lysis as well as proliferation were decreased in the presence of NECA or adenosine. Importantly, AB928 fully restored CAR T cell cytotoxicity, proliferation, and cytokine secretion in a dose dependent manner. Further, AB928 also restored antigen dependent cytokine secretion of human CAR T cells in the presence of NECA.ConclusionsHere we used the A2A/A2B dual antagonist AB928 to overcome adenosine-mediated suppression of CAR T cells. We found that AB928 enhanced important CAR T cell effector functions in the presence of the adenosine analogue, suggesting that combination therapy with AB928 may improve CAR T cell efficacy. This study was limited to in vitro experiments. To confirm the relevance of our findings, this combination therapy must be further investigated in an in vivo setting.Disclosure InformationM. Seifert: None. M. Benmebarek : None. B. Cadilha : None. J. Jobst: None. J. Dörr: None. T. Lorenzini: None. D. Dhoqina: None. J. Zhang: None. J. Zhang: None. U. Schindler: E. Ownership Interest (stock, stock options, patent or other intellectual property); Modest; Amgen Inc., Arcus Biosciences. Other; Significant; Arcus Biosciences. S. Endres: None. S. Kobold: B. Research Grant (principal investigator, collaborator or consultant and pending grants as well as grants already received); Significant; Arcus Biosciences.

scholarly journals B-CLL Mediated Resistance to CAR T Cell Therapy Via Insufficient Activation Is CAR-Independent

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 44-44
Author(s):  
McKensie Collins ◽  
Weimin Kong ◽  
Inyoung Jung ◽  
Stefan M Lundh ◽  
J. Joseph Melenhorst
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Research Funding ◽  
Cytokine Production ◽  
Cell Function ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Chronic Lymphocytic Leukemia (CLL) is a B cell malignancy that accounts for nearly 1/3rd of adult leukemia diagnoses in the Western world. Conventional chemo-immunotherapies initially control progression, but in the absence of curative options patients ultimately succumb to their disease. Chimeric Antigen Receptor (CAR) T cell therapy is potentially curative, but only 26% of CLL patients have a complete response. CLL-stimulated T cells have reduced effector functions and B-CLL cells themselves are believed to be immunosuppressive. Our work demonstrates that insufficient activation of CAR T cells by CLL cells mediates some of these effects and that the results are conserved between ROR1- and CD19-targeting CARs. Results: In this study we used an in vitro system to model the in vivo anti-tumor response in which CAR T cells serially engage with CLL cells. Multiple stimulations of CD19 or ROR1-targeting CAR T cells with primary CLL cells recapitulated many aspects of known T cell dysfunction including reduced proliferation, cytokine production, and activation. While the initial stimulation induced low level proliferation, subsequent stimulations failed to elicit additional effector functions. We further found that these functional defects were not permanent, and that CAR T cell function could be restored by switching to a stimulus with an aAPC (artificial Antigen Presenting Cell) control cell line. The aAPCs are well-characterized as potent stimulators of CAR T cell effector responses. Flow cytometry revealed that CLL-stimulated CAR T cells retained a non-activated, baseline differentiation profile, suggesting that CLL cells fail to stimulate CAR T cells rather than rendering them non-functional. One mechanism that could dampen activation is immune suppression. We assessed this at a high level by stimulating CAR T cells with CLL cells and aAPCs mixed at known ratios. However, even cultures containing 75% CLL cells stimulated proliferation and cytokine production. Extensive immune-phenotyping revealed high level expression of the IL-2 Receptor on 90% (18/20) of the B-CLL cells tested. Since cytokine sinking via IL-2 receptor expression is a well-known mechanism of regulatory T cell suppression, we hypothesized that CLL cells similarly sink IL-2, blunting T cell activation. To test this, we supplemented IL-2 into CLL/CAR T cell co-cultures and showed that this rescued proliferation but only partially restored cytokine production. In contrast to our hypothesis, analysis of cytokine production by flow cytometry showed that CLL-stimulated CAR T cells did not produce IL-2 following a 6- or 12-hour stimulus, but TNFα was expressed after 12-hours. Similarly, CAR T cell degranulation, a prerequisite for target cell lysis was triggered after CLL recognition. These data again suggested that CLL cells insufficiently stimulate CAR T cell cytokine production, but also showed that cytolytic activity against CLL cells is intact. We further proposed that CLL cells express insufficient levels of co-stimulatory and adhesion molecules to activate CAR T cells. Flow cytometry showed that most CLL cells expressed co-stimulatory and adhesion molecules at low levels; we hypothesized that up-regulating these molecules would enhance CAR T cell targeting of CLL cells. CLL cells were activated with CD40L and IL-4, which increased expression of CD54, CD58, CD80, and CD86. Stimulating CAR T cells with activated CLL cells enhanced CAR T cell proliferation and induced cell conjugate formation, indicating cell activation. Therefore, improving CLL stimulatory capacity can rescue T cell dysfunctions. To assess whether IL-2 addition and CD40 ligation were synergistic, we combined the two assays; however, we saw no additional improvement over IL-2 addition alone, suggesting that the two interventions may act upon the same pathway. Importantly, we also showed that rescue of CAR T cell function via IL-2 addition or CD40 ligation was not CAR-specific, as we observed the functional defects and subsequent rescue with both a ROR1-targeting CAR and the gold standard CD19-targeting CAR. Conclusions: Together, these data show that CAR T cell "defects" in CLL are actually insufficient activation, and improving the stimulatory capacity of CLL cells may enable better clinical responses. Further, this effect is not CAR-specific and these results may therefore be broadly applicable to multiple therapies for this disease. Disclosures Melenhorst: IASO Biotherapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Research Funding; Novartis: Other: Speaker, Research Funding; Johnson & Johnson: Consultancy, Other: Speaker; Simcere of America: Consultancy; Poseida Therapeutics: Consultancy.

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