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7028 Background: r/r B-ALL was reported as the most-threatening disease because of the low disease free survival even treatment with allogeneic hematopoietic stem cell transplantation. For overcoming conventional therapies limitation, autologous CD19CAR-T was performed in our clinical trials to induce remission in patients with r/r disease. 30 patients (from 7 clinical centers, in China) as volunteers with r/r B-ALL were treated by autologous CD19 CAR-T. Methods: 5 juveniles and 25 adults with r/r ALL received autologous CD19 targeted CAR-T, the doses between 1.03 × 106 CAR-T cells/kg and 10.09 × 106CAR-T cells/kg. These 30 cases(from 7 clinical centers, in China) were treated with CAR-T cells from May. 8 2015 to January. 4 2017 (Table1). Patients were monitored for a response. Highly standardized CAR T cell preparation protocol and manageable CRS in most were kept for no significant difference in 7 clinical centers. Results: After treated with CAR-T, a total of 30 cases (5 juveniles and 25 adults coming from 7 clinical centers, in China) with r/r B-ALL were all detected the CAR-T cells proliferated in the blood and bone marrow. The results showed that complete remission (CR) is 26/30(86.67% ) between day7-14 after CD19 CART cell infusion, and 25/30(83.33%) cases arrived at MRD negative. There is about 1/3 of the total cases receiving a repeat infusions following initial ones since these patients have no safety concerns. Additionaly, the severe Cytokine release syndrome (CRS) was 8/30(26.67%) of cases and 24/30(80%) of cases was seen CRS. The anti-IL6R agent tocilizumab and Methylprednisolone were effective confrontation Severe CRS. Conclusions: This is the first multicentre report to our knowledge of successful treatment of r/r ALL with anti-CD19 CAR T cells in China. Even r/r B-ALL with high-burden leukemia patients also was effective and associated with a high remission rate after infused autologous CD19 CAR-T).(NCT 02813837).

137 Background: The adoptive transfer of autologous T cells genetically modified to express a CD19-specific, 4-1BB/CD3ζ-signaling CAR (CTL019) has shown remarkable activity and induces long-term remissions in a subset of patients with relapsed/refractory chronic lymphocytic leukemia (CLL) and acute lymphoblastic leukemia (ALL). In ALL, CTL019 induces a complete response (CR) in over 90% of patients while in CLL 25% of patients obtain a CR. It is not fully understood why only certain patients respond to therapy. Methods: We employed next generation sequencing of RNA (RNAseq) to identify predictive indicators of response to CTL019. We performed RNAseq on leukapheresis and manufactured product T cells prior to re-infusion from 35 CLL and 7 pediatric ALL patients with heavily pre-treated and high-risk disease. To characterize potency, we performed RNAseq on the infusion product after stimulation with the CAR. Results: We find that durable remission in CLL is associated with gene expression signatures of early memory and T-effector cells, while T cells from non-responding patients are enriched in signatures of T-regulatory cells, terminal differentiation, and exhaustion. In following the results from CLL, we find that pediatric ALL manufactured T cells are significantly enriched for an early memory, naïve T cell state and all achieved a CR. In parallel in vitro experiments, stimulation of the infusion product further demonstrated that CTL019 cells from CRs have an increased capacity for activation upon stimulation. We tested if we could extend these observations to identify a phenotype of T cells that is predictive of response prior to CTL019 manufacturing and find that the signatures predictive of response at the pre-infusion stage are also observed at the earlier leukapheresis time point. Conclusions: These findings suggest that intrinsic T cell fitness dictates response to CAR T cells. These gene expression signatures, along with additional immunological biomarkers, may be used to identify which patients are most likely to respond to adoptive transfer strategies and suggest manufacturing modifications that might potentiate the generation of maximally efficacious infusion products. Clinical trial information: NCT01029366, NCT01747486, NCT01626495.

Meeting abstracts Management of advanced B cell malignancies refractory to standard chemotherapy is challenging with sub-optimal results. Recent clinical reports of durable, objective responses from adoptive transfer of anti-CD19 chimeric antigen receptor (CAR) T cells have accentuated the

Leukemia is the most common childhood malignancy and acute lymphoblastic leukemia (ALL) represents the largest sub-type. Despite remarkable improvements over the last 40 years, standard therapy fails in 10-20% of newly diagnosed patients. Survival for children with relapsed ALL is poor, and the development and implementation of novel therapeutic strategies in pediatric ALL are critical to further advancements. Immunotherapeutic approaches have been central to more novel ALL therapies. However, more recent innovation in antibody engineering has improved potency and efficacy, and antibody-drug conjugates (ADCs) are an especially attractive option in severely immunocompromised patients. An even more sophisticated antibody design is that of bi-specific T-cell engaging or BiTE® antibodies, which directly recruit effector T cells to augment the anti-neoplastic effect. This review focuses on blinatumomab, a bi-specific anti-CD19/CD3 antibody that has shown efficacy in adult patients with precursor B-ALL and is currently being evaluated in the pediatric setting.

TPS7075Background: ALL is the most common childhood malignancy. While approximately 80% of patients achieve durable complete remissions (CR) following initial treatment, the 20% of patients with relapsed or refractory disease have poor outcomes and require effective new therapies. An ongoing study at the National Cancer Institute (NCI) using anti-CD19 CAR T cells with CD28/CD3-zeta signaling domains showed complete remissions in 14 of 20 pediatric subjects with r/r ALL. (NCT01593696; Lee, Lancet 2015). KTE-C19 is an autologous, anti-CD-19 CAR T cell therapy that utilizes the same construct investigated in the NCI studies, manufactured in a streamlined 6 - 8 day process. Here we describe a phase 1/2 study evaluating KTE-C19 in pediatric and adolescent patients with r/r ALL. Methods: Subjects with r/r ALL will be treated with fixed dose fludarabine and cyclophosphamide conditioning chemotherapy followed by a single infusion of KTE-C19 at a target dose of 2 x 106 anti-CD19 CAR T cells/kg. Phase 1 will enroll...

7559This study is supported in part by The Leukemia & Lymphoma Society Therapy Acceleration Program Background: Durable remissions with CD28/CD3z anti-CD19 CAR T cells have been observed in patient...

Adoptive immunotherapy using T cells genetically engineered to express a chimeric antigen receptor that targets CD19, a B-cell differentiation antigen, has demonstrated impressive efficacy in a range of B-lymphoid malignancies. The latest results demonstrate the potential of this approach in patients with chemotherapy-refractory diffuse large B-cell lymphoma.

Cytotoxic T cells transduced with chimeric anti-CD19 receptors prevent engraftment of primary lymphoblastic leukemia in vivo

3028 Background: CAR engineered autologous T cell therapy has shown promising efficacy in B cell malignancies in an ongoing phase 1 study (Kochenderfer et al. J Clin Oncol 2014, ASH 2014). Anti-CD1...

8517 Background: CTL019, a 2nd-generation anti-CD19 CAR transduced via lentiviral vector, can induce regression of refractory B cell malignancies. Though multiple myeloma (MM) is reported to be CD1...

3079 Background: Engineered autologous T cell therapy is proving to be a promising method to treat a variety of tumor types. An ongoing National Cancer Institute (NCI) Phase 1/2a study in patients ...

B43(anti-CD19)-Genistein immunoconjugate targets genistein, a naturally occurring protein tyrosine kinase inhibitory isoflavone to the membrane-associated anti-apoptotic CD19-LYN complexes and triggers apoptotic cell death. In this preclinical study, the toxicity profiles of B43-Genistein as well as unconjugated genistein were evaluated in mice. B43-Genistein and genistein were administered either as single bolus injections or daily injections for 10 consecutive days via the intraperitoneal route to mice. Genistein was not toxic to mice at the highest dose of 40 mg/kg and no test article-related histopathological lesions were found in any of the 64 genistein-treated mice. B43-Genistein had a significantly longer elimination half-life and slower plasma and tissue clearance than unconjugated genistein. B43-Genistein was not toxic to mice at the highest single dose of 40 mg/kg or highest cumulative dose of 100 mg/kg and no test article-related histopathological lesions were found in any of the 108 mice treated with B43-genistein. To our knowledge, this is the first preclinical toxicity and pharmacokinetic study of a tyrosine kinase inhibitor-containing immunoconjugate.

TPS10072 Background: Outcomes remain poor for patients (pts) with relapsed or refractory (r/r) B-cell malignancies such as acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL). CD19 is an attractive therapeutic target because it is widely expressed on normal and malignant B cells throughout B-cell maturation but not on pluripotent stem cells or non–B-cell tissues. We have developed chimeric antigen receptor T cells to target CD19+ cells (CART-19 or CTL019). This approach involves patient-derived T cells that are genetically modified via lentiviral transduction to express a CD19 antigen recognition domain attached to intracellular signaling domains (TCRζ and 4-1BB) that mediate T-cell activation. A recent study in CLL showed that CART-19 therapy had potent activity with responses in 5/8 evaluable pts (3 CR, 2 PR). Pts achieving CR (two > 24 months and one > 5 months) remain in CR with detectable CART-19 cells (Porter et al. ASH 2012). Here we describe a study of CART-19 therapy in pediatric pts with r/r leukemia and lymphoma (NCT01626495). Methods: Pts eligible for this single-arm, open-label study are aged 1 to 24 years with r/r CD19+ B-cell malignancies, without a transplant option or having relapsed after allogeneic stem cell transplantation (ASCT). Pts will undergo leukapheresis to obtain T cells, which will be stimulated, expanded, and transduced ex vivo to express the chimeric antigen receptor. Pts may receive lymphodepleting chemotherapy prior to CART-19 infusion. Study objectives: determine the safety and feasibility of administering CART-19 therapy to pediatric pts, assess duration of in vivo survival of CART-19 cells, and measure antitumor response. There are 2 cohorts in the study: Cohort 1 includes pts who have not undergone ASCT and are not currently eligible for a transplant, and cohort 2 includes pts who relapsed after ASCT. Cells are collected from the recipient, not the donor, which allows for this approach to be used in pts s/p cord blood transplant, and which we hypothesize will reduce the risk of GVHD as a result of toleration of the T cells in the recipient. To date, 7 pts have been enrolled. Clinical trial information: NCT01626495.

TPS7132 Background: The poor prognosis and lack of effective treatment options for patients with r/r CLL highlight the need for novel therapies in this setting. CD19 is a promising anticancer target because it is broadly expressed on normal and malignant B cells through several stages of maturation but absent on pluripotent stem cells. CART-19 (CTL019) therapy involves adoptive transfer of autologous T cells genetically modified via lentiviral transduction to express chimeric antigen receptors (CAR) designed to target CD19+ cells. CART-19 cells express a CD19 antigen recognition domain combined with intracellular signaling domains, CD137 (4-1BB) and CD3-zeta, which mediate cytolytic T-cell activity. In patients with r/r CLL, CART-19 therapy showed potent antileukemic activity with long-term persistence of transduced cells at doses from 1.4 × 107 to 1.1 × 109 CART-19 cells. As of August 2012, 3 of 8 evaluable CLL patients achieved CR (two > 24 months and one > 5 months) and remain in CR with detectable CART-19 cells. Two patients had PR lasting 3 and 5 months, and 3 patients did not respond (Porter et al. NEJM. 2011; Kalos et al. Sci Transl Med. 2011; Porter et al. ASH 2012). Here, we describe a study to determine the optimal dose of CART-19 cells (NCT01747486). Methods: Adults with relapsed or persistent CLL or SLL after ≥ 2 previous therapies will undergo leukapheresis to obtain T cells, which will be stimulated, expanded, and lentivirus transduced ex vivo to express the CD19/4-1BB/CD3-zeta CAR. Patients will undergo lymphodepletion chemotherapy prior to infusion of CART-19 cells. In stage I of the II-stage trial, 30 patients will be randomized 1:1 and receive either 1-5 × 108 or 1-5 × 107 CART-19 T cells. The optimal dose in stage I will be selected based on clinical responses, feasibility, and tolerability. In stage II, 8 additional patients will be enrolled into the selected dose cohort. Study objectives are to determine the efficacy (CR rate within 3 months) and safety (CTCAE v 4.0) of each dose, in vivo CART-19 expansion, and manufacturing feasibility. Three patients have been enrolled as of January 2013. Clinical trial information: NCT01747486.

10008 Background: Despite intensive chemotherapy and HSCT, outcomes in relapsed/refractory pediatric B cell ALL and NHL are poor. To treat children with or without prior allogeneic-HSCT and quickly deliver therapy, we developed a Phase I trial of 19CARTs for both HSCT-naive and post-allo-HSCT patients where autologous-collected T cells are manufactured in 11 days. Methods: T cells collected on Day -11 by lymphopheresis were positively selected and activated using anti-CD3/CD28 beads then transduced with the CD19-CAR gene via retrovirus. Cells were infused after 7 additional days of expansion. Patients (Pt) received fludarabine and cyclophosphamide prior to receiving 1e6 19CARTs/kg. Results: A 59-65 fold expansion of 19CARTs with 39-65% transduction efficiency was achieved in Pt 1 and 3 (ALL, NHL). Pt 1 achieved a complete response (CR). Mild cytokine release syndrome was observed (Gr 3 fever, Gr 2 hypotension) correlating with mild elevation in IL6, GM-CSF, INFg and C reactive protein (CRP; Table). No other non-hematologic, CAR-related Gr ≥3 toxicities were observed. Pt 2 (ALL) received 2.8% of the targeted cell dose due to lack of cell expansion likely from recent prior chemotherapy but experienced a transient CR with significant 19CART expansion (15% blood, 5% marrow, 6% CSF). Importantly, 19CARTs were well tolerated without evidence of GVHD in these post-allo HSCT patients. Conclusions: Autologous-collected allogeneic derived 19CART cells can be rapidly manufactured and safely administered to children with ALL and NHL. Clinical activity can be achieved without GVHD despite inflammatory cytokine generation. 19CARTs offer a potentially effective strategy to treat post-HSCT relapse warranting further study. Clinical trial information: NCT01593696. [Table: see text]

6500^ Background: Blinatumomab is a bispecific T-cell engaging (BiTE) antibody that directs cytotoxic T-cells to CD19 expressing target cells. Methods: In adult patients with relapsed/refractory B-precursor ALL, a phase II dose ranging trial is being conducted to evaluate efficacy and safety of blinatumomab. The primary endpoint is the rate of hematological complete remission (CR) or CR with partial hematological recovery (CRh*) within 2 cycles of blinatumomab treatment. Blinatumomab is administered by continuous intravenous infusion for 28-days followed by a 14-day treatment-free interval. Responding patients can receive 3 additional cycles of treatment or proceed to bone marrow transplantation. Three dose levels were explored as shown in the table. Results: In total 36 patients have been enrolled, 25 are currently evaluable. Seventeen out of 25 treated patients (68%) reached a hematological CR/CRh* and a minimal residual disease (MRD) response (MRD level -4) within the first 2 cycles. Five out of 17 responders (29%) showed a CRh* due to partial recovery of platelets. For the first 18 patients, response duration is 7.1 months and the median follow-up time for overall survival (OS) is 9.7 months (median not reached). Six cases of relapses have been recorded of which 3 were CD19+, and 3 CD19-. As final dose 5 µg/m²/day in week 1 and 15 µg/m²/day for the remaining treatment (cohort 2a and 3) was selected. In these cohorts (n=12), the most common treatment emergent adverse events (TEAEs, all grade 1-2) were pyrexia (67%), headache (33%) and tremor (33%). TEAEs of grade ≥3 (7 in 5 patients, no grade 4), irrespective of relationship, were infections, confusion, epilepsy, hypertension and thrombocytopenia. Conclusions: The final dose was well-tolerated and produced an exceptionally high complete remission rate. A global phase 2 study to confirm these data is underway. [Table: see text]

TPS2619 Background: Complete remission (CR) rates for B-ALL in adults is high (>80%), but overall survival remains low (approximately 30%). Patients with relapsed disease have a very poor prognosis with a median survival measured in months. Therefore, there is a dire need for novel therapies for adults with relapsed or minimal residual B-ALL. To this end we have developed a novel T cell therapy for B cell malignancies using patient derived T cells genetically modified to express the 19-28z chimeric antigen receptor (CAR), an artificial T cell receptor specific to the CD19 antigen expressed on most B cell tumors. Human T cells retrovirally modified to express the 19-28z CAR successfully targets and eradicates B cell tumors in vitro and systemic human B cell cancers in mice. We have recently published the results of our initial Phase I clinical trial experience (Brentjens, Rivière et al., Blood 2011) utilizing this technology in adults with chronic lymphocytic leukemia. These results suggest clinical activity and demonstrate a persistence of 19-28z+ T cells that is inversely associated with tumor burden. These studies suggest that 19-28z+ T cells may be particularly effective in relapsed B-ALL because these tumors retain a degree of chemotherapy sensitivity, which will allow the infusion of T cells after salvage chemotherapy when patients have low tumor burdens. To our knowledge, this is the first clinical trial using autologous CD19 targeted T cells in adults with B-ALL. Methods: We are enrolling patients to a Phase I T cell dose escalation trial (NCT01044069). Adults with CD19+ B-ALL classified as a CR, relapsed, or refractory are eligible for enrollment. After patients are enrolled they are leukapheresed to obtain peripheral blood T cells, which are then retrovirally transduced to express the 19-28z CAR and expanded in our GMP gene transfer facility. Enrolled patients with relapsed or refractory B-ALL undergo a cycle of re-induction chemotherapy and conditioning cyclophosphamide followed by infusion of autologous 19-28z+ T cells. To date, 11 patients have been enrolled and 2 patients have been infused with 19-28z+ T cells.

8057 Background: The recommended dose (RD) of SAR3419 administered intravenously every 3 weeks (q3w) for 6 cycles is 160 mg/m2 and is 55 mg/m2 when administered weekly (q1w) for 8-12 doses. Reversible corneal deposits were dose limiting (DLT) in the q3w schedule. The q1w schedule was well tolerated and active. However, based on the occurrence of late/cumulative adverse events (AE) at the RD supported by pharmacokinetic (PK) analyses showing ADC plasma accumulation after 4 weekly doses, an optimized schedule consisting of 4 weekly doses followed by 4 bi-weekly doses at the RD was tested. Methods: The q1w study was extended to treat 25 pts with the optimized schedule for 8 to 12 doses. Results: Twenty-one pts were evaluable. Main histologies were diffuse large B-cell (DLBCL) (9; 43%) and follicular (6; 29%). Median number of prior regimens was 2 [1-8], 6 pts received prior autologous transplantation and 95% of pts were Ann Arbor stage III-IV at study entry. Median number of doses received was 8 as planned with a median relative dose intensity of 1.0 [0.8-1.0]. Most frequent AEs were asthenia (1 pt with grade 3) and gastrointestinal disorders in 7 pts each. No AE fulfilled the defined DLT criteria. Reversible grade 1 blurred vision/corneal event occurred in 1 pt. Grade 3-4 haematological toxicities were minor consisting of non complicated neutropenia in 4 pts, thrombocytopenia in 2 pts and anemia in 1 pt with no transfusion support. Six (29%) pts, among them 3 with DLBCL, achieved an objective response including 3 CRu (1 in a pt refractory to last regimen). In addition, 9 (43%) pts had stable disease. Response duration was [8-35+] weeks, 5 pts still responding at the cut-off date. Conclusions: The optimized administration schedule shows an improved safety profile compared to prior tested schedules. The clinical efficacy is preserved essentially in aggressive lymphoma. The optimized schedule is being assessed in 2 phase II studies evaluating SAR3419 either as a single agent or in combination with rituximab in pts with DLBCL histology.

2625 Background: Radioimmunotherapy of non-Hodgkin's lymphoma has proven effectiveness when using anti-CD20 radioconjugates. So far, two different constructs are approved by the FDA: Zevalin and Be...

Monoclonal antibodies directed against two human B cell-restricted antigens, CD19 and CD22, were conjugated to highly purified ricin A chain. These A chain immunotoxins (A-IT) were specifically cytotoxic to Daudi cells and normal human peripheral blood B cells in vitro. The concentration required for 50% inhibition of protein synthesis (IC50) in these cells ranged from 7.5 X 10(-10) M to 4.2 X 10(-9) M. The specific toxicities of these A-ITs for Daudi cells were augmented 2- to 6-fold in the presence of 20mM NH4Cl. These studies demonstrate that A-ITs specific for CD19 and CD22 may be useful in the clinical treatment of B cell malignancies.