Infusion Of Chimeric Antigen Receptor Research Articles

Third Generation CD19-CAR T Cells for Relapsed and Refractory Lymphoma and Leukemia Report from the Swedish Phase I/IIa Trial

Chimeric antigen receptor (CAR) T cells have shown promising results in patients with B cell malignancy. In preclinical studies we showed that CD19-targeting third generation (3G) CAR T cells containing signaling domains from both CD28 and 4-1BB as co-stimulatory molecules have greater activation and proliferation in response to antigens than 2G CARs containing CD28 only. Herein we report results from a phase I/IIa study (NCT:02132624) using these 3G CAR T cells. Patients with relapsed or refractory CD19+ B-cell malignancy were eligible, provided there was no curative treatment available. Of the first eleven patients reported, nine had lymphoma and two had acute lymphoblastic leukemia (ALL). Autologous CAR T cells were manufactured using a gamma retrovirus encoding the CAR and expanded by αCD3/αCD28/IL2. During CAR T cell production, all lymphoma patients received treatment to control tumor burden (-90 to -3 days before T cell infusion). Their treatment depended on the type of lymphoma and previous treatments. In addition, prior to T cell infusion (day -2 to -1) patients #6-11 received cyclophosphamide (500mg/m2) and fludarabine (25mg/m2) as conditioning to decrease immunosuppressive cells.The patients received one infusion of CAR T cells (2x107 cells/m2 patients 1 and 2; 1x108 patients 4, 5, 7, 8, 9; and 2x108 patients 6, 10, 11, 12). Patient #1 (DLBCL) had a mild cytokine release syndrome (CRS) after four weeks (never requiring treatment), followed by a complete response of his lymphoma. A relapse and a second CRS occurred after six weeks and he was treated with prednisone with good symptomatic effect and reduction of tumor size. The patient progressed after three months. Patients #2, 4, 5 (CLL, MCL, MCL) all progressed after 2, 1, and 3 months, respectively. Patient #6 (DLBCL) responded to treatment (CR) prior to T cell infusion and remained in complete remission for 6 months post T cell infusion. Patients #7 (CLL) and #9 (DLBCL) also responded to treatment prior to T cell infusion and remains in complete remission +4 and +5 months,respectively. The CLL patient has a tumor negative bone marrow. Patient #8 (FL-DLBCL) had a mild CRS but progressed after 1 month but. Patient #10 (ALL) experienced transient CNS toxicity followed by a complete response. However, at 3 months the patient relapsed with a CD19 negative ALL, accompanied by increased levels of immunosuppressive cells such as T regulatory cells and myeloid derived suppressor cells. Patient #11 (ALL) is in complete remission after a CRS (+3 month) and patient #12 (FL/Burkitt) had a major CRS requiring intensive care and a stable disease for one month before progression. The CAR transgene could be detected in blood at the time of clinical symptoms of response and most patients that progressed lost CAR signal.In summary, 6 of 11 patients (3 DLBCL, 1 CLL and 2 ALL) treated with increasing doses of 3rd generation CAR T cells in Sweden had CR or CCR. CRS occurred in 4/11 but was mild in all but one and CNS-toxicity occurred in 2/11 patients of which one required hospitalisation. Correlations between the levels of T regulatory cells and myeloid derived suppressor cells in blood and patient response are currently under investigation. DisclosuresBrenner:Bluebird Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Cell Medica: Other: Licensing Agreement; Celgene: Other: Collaborative Research Agreement. Loskog:Alligator Bioscience AB: Patents & Royalties; RePos Pharma AB: Membership on an entity's Board of Directors or advisory committees; Lokon Pharma AB: Employment, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; NEXTTOBE AB: Membership on an entity's Board of Directors or advisory committees; Vivolux AB: Membership on an entity's Board of Directors or advisory committees.

Allogeneic T-Cells Expressing an Anti-CD19 Chimeric Antigen Receptor Cause Remissions of B-Cell Malignancies after Allogeneic Hematopoietic Stem Cell Transplantation without Causing Graft-Versus-Host Disease

Introduction Progressive malignancy is the leading cause of death after allogeneic hematopoietic stem cell transplantation (alloHSCT). After alloHSCT, B-cell malignancies are often treated with infusions of unmanipulated donor lymphocytes (DLIs) from the transplant donor. DLIs are frequently not effective at eradicating malignancy, and DLIs often cause graft-versus-host disease (GVHD), which is a potentially lethal allogeneic immune response against normal recipient tissues. Methods We conducted a clinical trial of allogeneic T cells that were genetically engineered to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19. The CAR was encoded by a gamma-retroviral vector and included a CD28 costimulatory domain. Patients with B-cell malignancies after alloHSCT received a single infusion of CAR T cells. No chemotherapy or other therapies were administered. The T cells were obtained from each recipient's alloHSCT donor. Findings Eight of 20 treated patients obtained remissions, including 6 complete remissions (CR) and 2 partial remissions. The response rate was highest for acute lymphoblastic leukemia with 4/5 patients obtaining minimal-residual-disease-negative CRs, but responses also occurred in chronic lymphocytic leukemia (CLL) and lymphoma. The longest ongoing CR is 30+ months in a patient with CLL. No patient developed new-onset acute GVHD after CAR T-cells were infused. Toxicities included fever, tachycardia, and hypotension. Median peak blood CAR T-cell levels were higher in patients who obtained remissions (39 CAR+ cells/mL) than in patients who did not obtain remissions (2 CAR+ cells/mL, P=0.001). Presence of endogenous normal or malignant blood B lymphocytes before CAR T-cell infusion was associated with higher post-infusion median blood CAR T-cell levels (P=0.04). Compared to patients who did not obtain a remission of their malignancies, patients obtaining remissions had a higher CD8:CD4 ratio of blood CAR+ T cells at the time of peak CAR T-cell levels (P=0.007). The mean percentage of CAR+CD8+ T cells expressing the programmed cell death-1 (PD-1) protein increased from 12% at the time of infusion to 82% at the time of peak blood CAR T-cell levels (P<0.0001). The mean percentage of CAR+CD4+ T cells expressing PD-1 increased from 32% at the time of infusion to 91% at the time of peak blood CAR T-cell levels (P<0.0001). Interpretation Infusion of allogeneic anti-CD19 CAR T cells is a promising approach for treating B-cell malignancies after alloHSCT. Our findings point toward a future in which antigen-specific T-cell therapies will be an important part of the field of allogeneic hematopoietic stem cell transplantation. Table. PatientNumber Malignancy Transplant type Total T cellsinfused/kg Anti-CD19CAR-expressingT cells infused/kg Malignancyresponseat last follow-up(interval from infusion to last follow-up in months) 1 CLL URD 10/10 HLA match 1x106 0.4x106 SD (3) 2 DLBCL Sibling 2x106 0.7x106 SD (1) 3 CLL Sibling 4x106 2.4x106 PD 4 DLBCL Sibling 4x106 2.2x106 SD (31+) 5 CLL URD 10/10 HLA match 1.5x106 1.0x106 CR (30+) 6 MCL Sibling 7x106 4.6x106 SD (3) 7 CLL URD 10/10 HLA match 1x106 0.7x106 PD 8 MCL Sibling 7x106 3.9x106 SD (24+) 9 MCL URD 10/10 HLA match 4x106 2.2x106 PR (3) 10 MCL Sibling 10x106 7.8x106 SD (2) 11 CLL URD 9/10 HLA match 5x106 3.1x106 PR (12+) 12 ALL Ph+ Sibling 7x106 5.2x106 MRD-negative CR (15+) 13 MCL Sibling 10x106 7.1x106 SD (9) 14 ALL Ph-neg Sibling 10x106 7.0x106 MRD-negative CR (5) 15 ALL Ph-neg Sibling 10x106 6.9x106 MRD-negative CR (3) 16 ALL Ph-neg Sibling 7x106 5.6x106 PD 17 DLBCL Sibling 10x106 8.2x106 CR (6+) 18 DLBCL Sibling 10x106 3.1x106 SD (2) 19 FL transformed to DLBCL URD 10/10 HLA match 5x106 4.3x106 PD 20 ALL Ph-neg URD 9/10 HLA match 5x106 4.2x106 MRD-negative CR (3+)^ CLL, chronic lymphocytic leukemia; ALL Ph+, Philadelphia chromosome positive acute lymphoblastic leukemia; ALL Ph-neg, Philadelphia chromosome negative acute lymphoblastic leukemia; MCL, mantle cell lymphoma; DLBCL, diffuse large B-cell lymphoma; FL, follicular lymphoma; Sibling, human leukocyte antigen-matched sibling donor; URD, unrelated donor; HLA, human leukocyte antigen; PD, progressive disease; SD, stable disease; PR, partial remission; CR, complete remission; MRD-negative, minimal residual disease negative. ^Patient 20 underwent a second alloHSCT 3.5 months after anti-CD19 CAR T-cell infusion while in MRD-negative CR. Disclosures Goy: Celgene: Consultancy, Research Funding, Speakers Bureau; Allos, Biogen Idec, Celgene, Genentech, and Millennium. Gilead: Speakers Bureau. Rosenberg:Kite Pharma: Other: CRADA between Surgery Branch-NCI and Kite Pharma.

IGF1R- and ROR1-Specific CAR T Cells as a Potential Therapy for High Risk Sarcomas.

Patients with metastatic or recurrent and refractory sarcomas have a dismal prognosis. Therefore, new targeted therapies are urgently needed. This study was designed to evaluate chimeric antigen receptor (CAR) T cells targeting the type I insulin-like growth factor receptor (IGF1R) or tyrosine kinase-like orphan receptor 1 (ROR1) molecules for their therapeutic potential against sarcomas. Here, we report that IGF1R (15/15) and ROR1 (11/15) were highly expressed in sarcoma cell lines including Ewing sarcoma, osteosarcoma, alveolar or embryonal rhabdomyosarcoma, and fibrosarcoma. IGF1R and ROR1 CAR T cells derived from eight healthy donors using the Sleeping Beauty (SB) transposon system were cytotoxic against sarcoma cells and produced high levels of IFN-γ, TNF-α and IL-13 in an antigen-specific manner. IGF1R and ROR1 CAR T cells generated from three sarcoma patients released significant amounts of IFN-γ in response to sarcoma stimulation. The adoptive transfer of IGF1R and ROR1 CAR T cells derived from a sarcoma patient significantly reduced tumor growth in pre-established, systemically disseminated and localized osteosarcoma xenograft models in NSG mice. Infusion of IGF1R and ROR1 CAR T cells also prolonged animal survival in a localized sarcoma model using NOD/scid mice. Our data indicate that both IGF1R and ROR1 can be effectively targeted by SB modified CAR T cells and that such CAR T cells may be useful in the treatment of high risk sarcoma patients.

Interim Safety Analysis: a Phase I Trial of High Dose Therapy and Autologous Stem Cell Transplantation Followed By Infusion of Chimeric Antigen Receptor Modified T-Cells (19-28z CAR-T) Directed Against CD19+ B-Cells for Relapsed and Refractory Aggressive B Cell Non-Hodgkin Lymphoma (B-NHL)

Background: Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive B-NHL. While 50-80% of patients with DLBCL are cured with standard induction therapy, a large fraction of patients either relapse or have primary refractory (rel/ref) disease. High-dose therapy followed by autologous stem cell transplantation (HDT-ASCT) is the established standard of care for these patients. Despite this, approximately half of all rel/ref patients that are chemosensitive to salvage therapy are cured with this approach. Relapse is the major cause of treatment failure, and ultimately death, in these patients. Our group has demonstrated encouraging activity with 19-28z chimeric antigen receptor modified T cells (19-28z CAR-T) directed against CD19 in rel/ref ALL. We hypothesize that biologic optimization of cellular therapy with 19-28z CAR-T can be met immediately post-HDT-ASCT given: lymphoproliferative cytokine availability through lymphodepletion post-HDT, depletion of prohibitive regulatory cellular elements post-HDT and achievement of minimal residual disease prior to 19-28z CAR-T consolidation. Herein, we report safety data on the first 6 patients of the phase I MSKCC #12-117: 19-28z CAR-T post HDT-ASCT for poor-risk rel/ref aggressive B-NHL.Methods: Eligibility for this study includes rel/ref aggressive B-NHL appropriate for HDT-ASCT as defined by chemosensitivity to salvage therapy and poor risk features including: 1) FDG-PET positivity following 2 cycles of salvage therapy or 2) bone marrow involvement of B-NHL at the time of rel/ref clinical restaging. Patients underwent separate apheresis for CD34+ progenitor cells and CD3+ T cells. T cells were transduced with a retrovirus encoding a CAR construct composed of anti-CD19 scFV linked to CD28 and CD3ζ signaling domains (19-28z). Patients were admitted for BEAM conditioned HDT and ASCT occurred day 0. Pegfilgrastim was administered on day+1 and 19-28z CAR-T dose per phase I study was split on days +2 and +3.Results: This analysis includes the first six patients, all male, on the phase I study. The median age is 61 (range 34-68) years at the time of HDT-ASCT. Diagnoses included: n=2 relapsed and transformed follicular lymphoma (one with double-hit biology), n=3 relapsed DLBCL (one CD5+) and one subject with relapsed and transformed marginal zone lymphoma involving the bone marrow. Five patients were treated at dose level #1 (5 x106 19-28z CAR-T/kg) with no dose-limiting toxicity (DLT) observed. Four of the five patients at dose level #1 experienced grade 3 febrile neutropenia and one patient met-criterion for non-severe cytokine-release syndrome (nCRS) effectively treated with tocilizumab 4 mg/kg x1. One patient was treated at dose-level #2, 1 x107 CAR-T/kg, and experienced a DLT of grade 4 severe CRS (sCRS) manifested with acute kidney injury, hypotension and mental status changes effectively treated and fully recovered with tocilizumab in combination with dexamethasone. Peak CRP in all patients was observed at a median of 3.5 days (range 3-4 days) post-19-28z CAR-T infusion (median peak CRP= 17 mg/dL, range: 5-43.1 mg/dL), with CRP >20 mg/dL identified in the two patients that experienced CRS (nCRS=27 mg/dL, sCRS=43 mg/dL). Previously associated serum cytokine elevations (Davila et al Sci Trans Med, 2014) were observed in the two patients that experienced CRS (Figure). All patients engrafted neutrophils at a median of 10 days (range: 9-10 days) post-ASCT, and achieved a complete remission at first post-HDT-ASCT restaging. No sequelae of autoimmune phenomenon were observed. At a median follow-up of six months, with 2 patients >one year post HDT-ASCT, all patients remain alive and in remission.Conclusions: This is the first report of 19-28z CAR-T cells in conjunction with consolidative HDT-ASCT for poor-risk rel/ref aggressive B-NHL. No DLTs have been observed at dose level #1, 5 x106 19-28z CAR-T/kg, while sCRS was observed in n=1 at 1 x107 CAR-T/kg resulting in a DLT. CRS was associated with pro-inflammatory serum cytokine elevation. CRS was aborted with tocilizumab with (sCRS=1) or without (nCRS=1) dexamethasone. All patients engrafted neutrophils at the expected time point. The use of 19-28z CAR T cells is a promising approach in this small group of poor-risk PET+ NHL patients undergoing autologous transplant. This is an ongoing trial and updated data will be presented. [Display omitted] DisclosuresRiviere:Juno Therapeutics: Consultancy, scientific co-founders Other. Sadelain:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other. Brentjens:Juno Therapeutics: Consultancy, scientific co-founder Other.

Effective Treatment Of Chemotherapy-Refractory Diffuse Large B-Cell Lymphoma With Autologous T Cells Genetically-Engineered To Express An Anti-CD19 Chimeric Antigen Receptor

▪We have treated 20 patients and administered 23 total T-cell infusions on a clinical trial of autologous T cells genetically modified to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19. This is the largest reported clinical trial of anti-CD19-CAR T cells. The first 9 CAR-T-cell treatments have been reported (Kochenderfer et al. Blood 2010 and Blood 2012). This abstract communicates unreported results from 14 patients who received anti-CD19-CAR T cells produced with a new 10-day culture process. These patients did not receive exogenous interleukin-2. Of these 14 patients, 5 obtained complete remissions (CR), and 6 obtained partial remissions (PR), (see table).TablePatientAge/GenderMalignancyNumberof priortherapiesTotal cyclo-phosphamidedose(mg/kg)Number ofCAR+ T cellsinfused(X106/kg)Response(timeafter cellinfusion inmonths)156/MSMZL41205PR (20+)243/FPMBCL4605CR (19+)361/MCLL2604CR (16+)430/FPMBCL31202.5NE563/MCLL41202.5CR (10+)648/MCLL1602.5CR (7+)742/MDLBCL5602.5CR (4+)844/FPMBCL10602.5PR (6+)938/MPMBCL31202.5SD (1)1057/FLow-grade NHL4601PR (4+)1158/FDLBCL from CLL13601PR (2)1260/FDLBCL3601SD (1+)1368/MCLL4601PR (2+)1443/MDLBCL2601PR (1+)The CAR used in this work is encoded by a gammaretrovirus and incorporates the variable regions of an anti-CD19 antibody, part of CD28, and part of CD3-zeta. A mean of 70.5% of the infused T cells expressed the CAR, and the infused cells produced cytokines and degranulated in a CD19-specific manner. Because prior chemotherapy has been shown to enhance the activity of adoptively-transferred T cells, patients received cyclophosphamide (total doses shown in table) plus fludarabine (25 mg/m2 daily for 5 days) before a single infusion of anti-CD19-CAR-transduced T cells.This is the first report of successful treatment of chemotherapy-refractory primary mediastinal B-cell lymphoma (PMBCL) and diffuse large B-cell lymphoma not otherwise specified (DLBCL) with anti-CD19-CAR T cells. All of the 8 treated patients with either PMBCL or DLBCL were chemotherapy-refractory, and 5 of these 8 patients obtained either a CR or PR on this trial. We defined chemotherapy-refractory as progression or no response 1 month after the end of the most recent chemotherapy. For example, Patient 2 had PMBCL that was refractory to 3 different chemotherapy regimens and that relapsed after radiation therapy. Patient 2 obtained a CR after infusion of anti-CD19 CAR T cells and remains in CR 19 months post-infusion.Blood B-cell depletion lasting more than 3 months occurred in 3 of 3 evaluable patients. Most patients were not evaluable for B-cell depletion due to B-cell depletion by prior treatments. One patient died suddenly of unknown etiology 16 days after infusion of CAR T cells. Acute toxicities including fever, hypotension, and delirium occurred after infusion of anti-CD19-CAR T cells. The toxicities resolved in less than 3 weeks after the cell infusion and were temporally associated with elevated serum interleukin-6 and interferon gamma levels in most patients. Peak blood levels of cells containing the CAR gene ranged from 2.3% to 66.5% of blood mononuclear cells. These results demonstrate the feasibility of treating patients with chemotherapy-refractory B-cell malignancies by using autologous anti-CD19 CAR T cells. The numerous remissions obtained should encourage further development of this approach.SMZL, splenic marginal zone lymphoma; PMBCL, primary mediastinal B-cell lymphoma; CLL, chronic lymphocytic leukemia; DLBCL, diffuse large B-cell lymphoma not otherwise specified. CR, complete remission; NE, not evaluable; PR, partial remission; SD, stable disease. (+) indicates an ongoing response. Disclosures:Rosenberg:Kite Pharma: Research Funding.

Donor-Derived Anti-CD19 Chimeric-Antigen-Receptor-Expressing T Cells Cause Regression Of Malignancy Persisting After Allogeneic Hematopoietic Stem Cell Transplantation

▪Progressive malignancy is a leading cause of death in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). To improve treatment of B-cell malignancies that persist despite alloHSCT, we conducted a clinical trial of allogeneic T cells genetically modified to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19. Ten patients were treated on this trial. Four patients were recipients of human-leukocyte-antigen (HLA)-matched unrelated donor (URD) transplants and 6 patients were recipients of HLA-matched sibling transplants. T cells for genetic modification were obtained from each patient's healthy alloHSCT donor. Patients received a single infusion of anti-CD19-CAR T cells. Cell doses ranged from 1x106 to 10x106 T cells/kg. A mean of 58% of the infused cells expressed the CAR. Patients did not receive chemotherapy or other anti-malignancy therapy with the CAR-T-cell infusions, so the responses observed in these patients are not confounded by the effects of chemotherapy. In contrast to other reports of successful treatment of B-cell malignancies with anti-CD19-CAR T cells, the patients on this study were not lymphocyte-depleted at the time of the CAR-T-cell infusions.Two patients with chronic lymphocytic leukemia (CLL) refractory to standard unmanipulated allogeneic donor lymphocyte infusions (DLIs) had regressions of large malignant lymph node masses after infusion of allogeneic anti-CD19-CAR T cells. One of these CLL patients obtained a complete remission that is ongoing 9 months after treatment with allogeneic anti-CD19-CAR T cells. This patient also had complete eradication of blood B cells within 9 days after her CAR-T-cell infusion. Another patient had tumor lysis syndrome requiring rasburicase treatment as his CLL dramatically regressed in lymph nodes, bone marrow, and blood within 2 weeks of his anti-CD19-CAR-T-cell infusion. A patient with mantle cell lymphoma obtained a partial remission that is ongoing 3 months after infusion of anti-CD19-CAR T cells. A fourth patient with diffuse large B-cell lymphoma has ongoing stable disease 11 months after infusion of anti-CD19-CAR T cells. The other 6 treated patients all had short periods of stable malignancy or progressive disease after their CAR-T-cell infusions. Specific eradication of blood B cells occurred after infusion of CAR T cells in 3 of 4 patients with measurable blood B cells pretreatment. None of the patients treated on this study developed GVHD after their anti-CD19-CAR-T-cell infusions, despite the fact that 6 of 10 treated patients had experienced GVHD at earlier time-points after their most recent alloHSCT. One patient, who had a history of cardiac dysfunction with prior acute illnesses, had temporary cardiac dysfunction after infusion of anti-CD19-CAR T cells. The most prominent toxicities experienced by patients were fever and hypotension; these peaked 5 to 12 days after CAR-T-cell infusions and resolved within 14 days after the T-cell infusions. Two patients had Grade 3 fever, and 2 patients had Grade 3 hypotension. No patients experienced Grade 4 toxicities that were attributable to the CAR-T-cell infusions. Elevated levels of serum interferon gamma were detected in 3 patients at the time that they were experiencing toxicities.We detected cells containing the anti-CD19-CAR gene in the blood of 8 of 10 patients. The peak blood levels of CAR T cells varied from undetec to 2.8% of peripheral blood mononuclear cells. The persistence of the CAR T cells in the blood of patients was limited to one month or less. When we assessed T cells from the blood of patients ex vivo, we found elevated levels of the T-cell inhibitory molecule programmed cell death protein-1 (PD-1) on CAR+ T cells compared to CAR-negative T cells. These results show for the first time that small numbers of donor-derived allogeneic anti-CD19-CAR T cells can cause regression of highly treatment-resistant B-cell malignancies after alloHSCT without causing GVHD. Malignancies that were resistant to standard DLIs regressed after anti-CD19-CAR-T-cell infusions. Future goals for improving this approach include enhancing the persistence of anti-CD19-CAR T cells and reducing toxicities. Infusion of allogeneic T cells genetically modified to recognize malignancy-associated antigens is a promising approach for treating residual malignancy after alloHSCT. Disclosures:No relevant conflicts of interest to declare.

CD19 Targeted Allogeneic EBV-Specific T Cells for the Treatment of Relapsed ALL in Pediatric Patients Post HSCT

AbstractAbstract 353T cells can be genetically modified to target tumor antigens through the expression of a chimeric antigen receptor (CAR). CAR modified T cells targeting the CD19 antigen is a novel therapeutic approach for patients with relapse B-ALL following allo-HSCT. We have previously demonstrated donor derived Epstein-Barr virus specific cytotoxic T cells (EBV-CTLs) can be safely infused in patients following allo-HSCT. Following retroviral gene transfer with our CD19-specific CAR (19–28z), EBV-CTLs demonstrate in vitro cytotoxicity against CD19+ targets, retain EBV-specificity without allogeneic reactivity, and in vivo, eradicate systemic Burkitt lymphoma in a SCID/Beige murine model. Based on our preclinical studies we have initiated a phase I dose escalation clinical trial (NCT01430390) in pediatric patients with relapsed CD19+ B-ALL following allo-HSCT utilizing donor 19–28z+ EBV-CTLs. Three patients have received conditioning chemotherapy (fludarabine 25mg/m2 × 5 days) followed by infusion of CAR modified EBV-CTLs without infusion related toxicity. Subsequently, patient 1 and 3 safely received additional T cell infusions without (patient 1) and with (patient 3; cyclophosphamide) conditioning chemotherapy. Total CAR+ T cell dose for each infusion ranged from 1.4 – 4.1×105 cells/kg (1×106 total EBV-CTLs/kg per infusion). Patient 1 developed fever and biopsy proven skin GVHD (grade II) three days following his first infusion which resolved 2 weeks after starting topical steroids. Modified T cells were detected by Q-PCR in the bone marrow and peripheral blood up to 3 and 18 weeks respectively in patient 1 following first infusion, up to 2 weeks in the peripheral blood in patient 2, and have been below the limit of detection in patient 3. Patient 1 died from progressive disease 29 weeks following first infusion and patient 2 died from progressive disease 19 weeks post infusion. Patient 3, initially treated in remission following salvage chemotherapy, has no evidence of disease (NED) 15 months after last extramedullary relapse and 5 months post first infusion of 19–28z+ EBV-CTLs. These early results demonstrate the feasibility of allogeneic 1928z+ EBV-CTL infusions without the development of significant GVHD post allo-HSCT. Subsequent cohorts of patients will receive dose escalation of modified T cells and will be evaluated for safety, persistence of 19–28z+ EBV-CTLs, and for anti-tumor efficacy. Disclosures:No relevant conflicts of interest to declare.

Efficacy and safety of adoptive immunotherapy using anti-CD19 chimeric antigen receptor transduced T-cells: a systematic review of phase I clinical trials

There remain some key questions regarding the adoptive infusion of chimeric antigen receptor (CAR) transduced T-cells in the clinical setting. This article systematically reviews the phase I clinical trials using CARs targeting CD19 in B-lineage malignancies. Twenty-nine patients were enrolled and the 6-month progression free survival for this cohort was 50.0 ± 9.9%. Univariate analysis showed that patients benefited from lymphodepletion before CAR+T-cell infusion and the administration of interleukin-2 (IL-2). Longer-term persistence (≥ 4 weeks) and stronger expansion of CAR+ T-cells in the blood and higher peak serum interferon-γ (IFN-γ) level (≥ 200 pg/mL) were also related to superior outcome. Regarding treatment-related adverse events, the most prominent toxicities were fever, rigors, chills, acute renal failure, hypotension and capillary leak syndrome. In conclusion, anti-CD19 CAR+ T-cells have shown some benefits in patients with B-lineage malignancies and are well tolerated in most patients. Preconditioning and cytokine supplement are required to improve the clinical outcome.

The Effects of Co-Stimulatory Endodomains on the Fate of T Cells Expressing a Tumor Directed Chimeric Antigen Receptor (CAR) In Human Subjects with B Cell Malignancies

AbstractAbstract 3949B cell lymphomas have been effectively treated by immunotherapy, including monoclonal antibodies (MAbs) and adoptive T cell transfer. To extend this success, investigators have genetically modified T cells to express a B cell specific antibody incorporated in an artificial chimeric antigen receptor (CAR), essentially combining antibody and cell-based approaches. Early B cell directed CARs combined the antigen binding domains of the variable regions of a CD19 or CD20 MAb (scFv) with the CD3ζ endodomain of the TCR/CD3 complex. Although such CARs confer potent cytotoxic function to T cells, initial clinical trials showed that T cells modified to express CARs engineered in this way had limited in vivo persistence, apparently receiving insufficient costimulation following CAR engagement.To overcome the above limitations, a multiplicity of costimulatory endodomains, including CD28, 41BB or OX40, have been incorporated into the CAR molecule. Because of patient heterogeneity, it has proved difficult to draw definitive conclusions about the relative expansion, persistence and effectiveness of cells with each modification, so that their comparative value in human subjects remains speculative. We therefore designed a phase I, dose escalation clinical trial in which patients with refractory/relapsed B cell malignancies were simultaneously infused with two autologous T cell products. Both express a CAR with an identical CD19-specific exodomain, but one CAR also has a CD28-ζ endodomain while the other expresses only a ζ endodomain. With this study design, each patient acts as a “self-control”, allowing us to directly discover the consequences of CD28 costimulation for the fate of the T cells in vivo.We enrolled two patients at each of the three cell dose levels (1st level = 2×107/m2 of each product; 2nd level = 1×108/m2; 3rd level = 2×108/m2). End points of the study were safety, persistence of each of the two generations of CAR-modified T cells, and assessment of antitumor activity. T cell products were generated by activation of autologous PBMC with immobilized OKT3 and gene modified with retroviral vectors encoding either CAR.19ζ or CAR.19-28ζ. After transduction, T cells were expanded ex vivo for a median of 14 days (range 6–18) in the presence of IL-2. CAR expression was 42%±18% and 49%±16% for CAR.19ζ and CAR.19-28ζ, respectively. This corresponded to 51,246±16,795 and 18,283±9,484 transgene copy numbers/μg DNA, respectively, as measured by Q-PCR. Products contained both CD8+ cells (CAR.19ζ = 49%±22%, CAR.19-28ζ = 48%±22%). Few naïve T cells were present in either transduced population (CD45RA+ = 6%±5% and 6%±6%, respectively), and memory T cells predominated in both (CD45R0+CD62L+ = 50%±24% and 47%±66%, respectively). Both T cell components equally and specifically targeted CD19+ tumors in vitro as assessed by 51Cr release assays (specific lysis was 53%±10% for CAR.19ζ and 65%±19% for CAR.19-28ζ at a 20:1 E:T ratio). All infusions were well tolerated in all patients. Persistence of CAR+ T cell was assessed in peripheral blood by Q-PCR assays specific for CAR.19ζ and CAR.19-28ζ.Molecular signals for CAR.19-28ζ began at a low level after infusion, but progressively increased (7 to 63 fold) to peak at 1–2 weeks post infusion, before declining to background levels over the ensuing 8 to 13 weeks. By contrast, molecular signals corresponding to CAR.19ζ+ cells were barely detectable after infusion, showed no expansion, and rapidly disappeared. Currently 4 patients are evaluable for disease response; 2 had stable disease for up to 6 months and 2 had progressive disease.Hence, infusion of both CAR.19ζ and CD19-28ζ T cells has been safe at current doses. Direct comparison of each cell product in individual patients indicates that inclusion of the CD28 costimulatory endodomain (2nd generation CAR) enhances expansion and persistence. Nonetheless, both the limited expansion and persistence and the modest clinical effects suggest that additional modifications will need to be made to CAR endodomains to optimize the benefits of this therapy. We suggest our approach will allow these modifications to be evaluated systematically and directly even in small-scale clinical studies. Disclosures:Off Label Use: T cell products in studies conducted under INDs.

Non-Integrating Gene Transfer To Redirect Specificity of Lymphocytes towards Pediatric CD19+ Malignancies

Pediatric B-lineage malignancies, such as acute lymphoblastic leukemia (B-ALL), generally have a poor prognosis upon relapse of tumor cells exhibiting resistance to conventional chemotherapy. In the absence of new commercially-available therapies for refractory pediatric cancers, it is up to pediatric oncologists to develop and apply new therapeutics. One candidate targeted therapy for B-lineage leukemia/lymphoma, is adoptive transfer of autologous T cells genetically modified to express a chimeric antigen receptor (CAR) and rendered specific for CD19. However, the broad adoption of T-cell gene therapy for children is limited by the expense to produce and release expression vectors and cell products and the risk of insertional mutagenesis. Therefore, we are developing an approach to express the CAR without integration of transgene and therefore without causing genotoxicity. Here we demonstrate that non-viral gene transfer of vector-free in vitro-transcribed messenger ribonucleic acid (mRNA) can efficiently introduce CAR into T cells. We demonstrate, using a commercially available electroporator, that codon-optimized mRNA coding for CD19-specific CAR is expressed on primary human T cells (Figure 1A) that redirects the specificity of CD19+ tumors (Figure 1B). When scaled-up for clinical trials, the electro-transfer of one or more mRNA species into T cells has the advantage of (i) ex vivo manipulation of T cells with preservation of homing receptors for lymph nodes and bone marrow (sites of leukemia/lymphoma), (ii) availability of clinically-meaningful numbers of genetically manipulated T cells within a day of apheresis, (iii) high levels of transgene expression, (iv) reduced cost (preparation of clinical-grade plasmid and mRNA compared with recombinant virus), and (iv) safety (no insertional mutagenesis). The relative ease of gene/mRNA transfer coupled with minimal manipulation of large numbers of T cells allows investigators to give patients multiple doses using existing infrastructure such as already widely exists for processing hematopoietic stem cells and blood banking. We are preparing a multi-institution clinical trial in which pediatric patients with refractory B-ALL receive personalized medication, prepared at each site, in the form of recursive infusions of CAR+ T cells repetitively electroporated with mRNA. This application of transient transfection to adoptive immunotherapy is expected to be of wide appeal for pediatric and adult patients alike with tumors that can be targeted by CAR. [Display omitted]