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Despite the success of autologous anti-CD19 CAR T cell therapy in B-Acute lymphoblastic leukaemia (B-ALL) and Diffuse Large B Cell Lymphoma (DLBCL), treatment failures occur. One contributing factor may be the intrinsic T cell fitness of the CAR T cell product that is influenced by the underlying malignancy and prior treatments. With the advent of gene editing, 'off the shelf' non-HLA matched healthy donor (HD) CAR T cells are under investigation for the treatment of patients (pts) in clinical trials. UCART19 (S68587) is a first-in-class allogeneic CAR T cell product expressing a second generation anti-CD19 CAR with TALEN®-mediated gene knockouts of T cell receptor alpha chain (TRAC) and CD52 to prevent graft versus host disease and to render them resistant to anti-CD52 antibody used for lymphodepletion. Preliminary clinical trial data on the use of UCART19 in B-ALL was previously reported at ASH (Benjamin et al, 2018). The phenotypic and functional characteristics of CAR T cell products manufactured from B-ALL, Chronic Lymphocytic Leukaemia (CLL) and DLBCL pts were compared to young adult healthy donor (HD) CAR T cell products. In addition, potential effects related to knocking out TRAC in HD TCR-CAR T cells were examined. Thawed PBMCs from B-ALL, CLL, DLBCL pts and HDs underwent T cell enrichment, activation with anti-CD3/CD28 beads and IL-2, followed by transduction with anti-CD19 4-1BB CD3ζ lentiviral CAR construct and expansion. HD TCR- CAR T cells were manufactured by electroporation of HD CAR T cells with mRNA coding for TRAC TALEN® and residual TCRαβ+cells were removed by magnetic bead selection. CAR expression levels, T cell subsets, and exhaustion markers were examined by flow cytometry. Expression of activation markers CD25 and CD69 was measured in response to co-culture with the CD19+cell line NALM-6. Cytotoxicity against NALM-6 and Raji was assessed and antigen-mediated proliferation measured over 14 days. HD CAR T cells (n=11) expanded significantly more during manufacture than CAR T cells derived from B-ALL (n=9), CLL (n=8) or DLBCL (n=8) pts. As expected, the electroporation step resulted in a transient decrease in viability which recovered over time in culture (n=10). Median CAR expression level was higher on CLL CAR T cell products compared to those from B-ALL pts and HDs, thought to be due to a higher CD4:CD8 ratio in some CLL products. As a consequence of TCR knockout, CD3 expression was lost on HD TCR- CAR T cells (n=10), apart from a small population of γδ CAR T cells. CLL and DLBCL CD8+CAR+cells expressed higher levels of PD1 than HD CD8+CAR+cells. DLBCL CD4+CAR+cells also expressed significantly higher levels of PD1 than HD or HD TCR-CD4+CAR+T cells. CAR+CD8+CD27+PD1- T cells have been previously described as a functionally important population that correlated with clinical outcome in pts who received CLL CAR T cells (Fraietta et al, 2018). We found HD (n=13) and HD TCR- (n=10) CAR T cells had significantly more CD8+CD27+PD1- CAR T cells compared to those derived from CLL (n=8) and DLBCL (n=6) pts, but similar levels to B-ALL pts (n=10). In the absence of CD19 antigen, DLBCL CAR+CD8+ T cells (n=6) had greater expression of CD25 and CD69. However, in response to stimulation with CD19+ NALM-6 cells, HD (n=12), HD TCR- (n=10) and B-ALL (n=10) CAR T cells had higher fold increase in CD69+ cells compared to DLBCL (n=6) CAR T cells. On paired analysis (n=6), no difference was seen in activation in response to CD19 antigen on HD compared to HD TCR- CAR T cells. All CAR T cell products demonstrated comparable cytotoxicity against NALM-6 and Raji cell lines in short term in vitro assays. However, long-term cytotoxicity will be evaluated in a murine model. We performed a detailed comparison of the phenotypic and functional characteristics of CAR T cells derived from pts with B-cell malignancies and HDs. DLBCL CAR T cells showed lower antigen specific activation but higher baseline activation which could lead to more differentiated exhausted T cells. CAR T cells derived from HDs show a higher proportion of the therapeutically relevant CAR+CD8+CD27+PD1- cells compared to patients with mature B cell malignancies (CLL and DLBCL), which is maintained after TRAC knockout. This suggests allogeneic CAR T cells, such as UCART19, may provide a more effective product for pts with T cell dysfunction. Disclosures Graham: Gillead: Other: Funding to attend educational meeting; Servier: Research Funding. Jozwik:Servier: Research Funding. Metelo:Pfizer: Research Funding; Allogene: Research Funding. Almena-Carrasco:Servier: Employment. Peranzoni:Servier: Employment. Ramsay:Celgene Corporation: Research Funding; Roche Glycart AG: Research Funding. Dupouy:Servier: Employment. Farzaneh:Autolus Ltd: Equity Ownership, Research Funding. Patten:Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria; Roche: Honoraria, Research Funding. Benjamin:Amgen: Honoraria; Allogene: Research Funding; Gilead: Honoraria; Servier: Research Funding; Eusapharm: Consultancy; Pfizer: Research Funding; Takeda: Honoraria; Novartis: Honoraria.

Background After European Medicines Agency (EMA) approval of axicabtagene ciloleucel and tisagenlecleucel for the treatment of relapsed/refractory (r/r) high-grade lymphoma in 2018, England was one of the first European countries granting fully funded access to these CD19 CAR-T therapies. Both products are available through the National Health Service England (NHSE) Cancer Drug Fund until their cost-effectiveness has been determined. The NHSE CAR-T program has been set up in a structure aiming to implement robust and transparent criteria for patient selection and to ensure equity of treatment access: CAR-T slots are approved by a weekly National CAR-T Clinical Panel (NCCP), consisting of independent clinical experts, patient representatives, and delegates from each CAR-T centre; treatment is delivered in 7 geographically spread commissioned CAR-T centres (Birmingham, Bristol, King's College Hospital London, University Hospital London, The Christie Manchester, Manchester Royal Infirmary, Newcastle). Here, we report prospective data on the first 122 lymphoma patients approved by the NCCP. Methods Patients with r/r high-grade lymphoma referred to the NCCP between December 2018 and July 2019 and deemed eligible for treatment with CD19 CAR-T were analysed. Eligibility was assessed in the CAR-T centre's tumor board, based on organ function and fitness (performance status 0/1), absence of active CNS disease, and biopsy confirmation of r/r high-grade lymphoma. The final decision on patient eligibility was made by consensus through the NCCP independent clinical panel. CAR-T product selection for each patient was done by the CAR-T centre, mainly on the basis of manufacturing slot availability. Results 122 patients were approved for treatment with CD19 CAR-T therapy by the panel. CAR-T centres selected 76 patients for axicabtagene ciloleucel and 46 for tisagenlecleucel. Patients' median age was 56 years (range 18-75). 62% were male. 87 (71%) patients had de novo diffuse large B-cell lymphoma, 29 (24%) transformed lymphoma (23 from follicular- and 6 from marginal zone lymphoma), and 6 (5%) primary mediastinal B-cell lymphoma. 96 (79%) patients had biopsy confirmation of disease prior to submission. 71 (58%) patients had received 2 prior lines of therapy for high-grade lymphoma, 51 (42%) patients 3 or more treatment lines (maximum 6). 5 patients had previous allogeneic, 19 previous autologous transplant. 88% of patients (107/122) were refractory to the last line of treatment (stable- or progressive disease (PD) or relapse within 6 months). Among 122 patients, 112 completed leukapheresis, 3 are awaiting the procedure, and 7 patients did not proceed (6 due to PD, 1 opted for radical radiotherapy). 57 of 112 patients were infused at the time of abstract submission, 42 are awaiting CAR-T infusion. 10 patients did not proceed to infusion due to disease progression and clinical deterioration (3 with CNS relapse), 2 due to manufacturing failure. One patient achieved a complete response following bridging therapy and is currently monitored. 84% (88/105) patients received bridging therapy between the time of NCCP approval and CAR-T infusion (median 64 days), 62 had chemotherapy, 9 radiotherapy, and 17 steroids only. Details on bridging therapy, treatment-related toxicities and outcomes will be provided at the meeting, by which time approximately 62 patients will have completed their 3 months PET response assessment. Conclusion NHSE has successfully implemented a national structure for providing licenced CAR-T products in England, enabling equity of access and oversight on capacity and patient outcomes, which can serve as a model for newly licenced, cost-intense and complex cell- and gene therapies in the future. The prospective and centralised nature of this dataset offers a true reflection of the real-world patient population undergoing CAR-T therapy in England. Disclosures Kuhnl: Kite Gilead: Honoraria. Roddie:Gilead: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Novartis: Consultancy. Menne:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Kyowa Kirin: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau. Sanderson:Kite/Gilead: Honoraria. Osborne:Novartis: Other: Travel; Pfizer: Honoraria, Speakers Bureau; MSD: Consultancy; Takeda: Consultancy, Honoraria, Other: Travel, Speakers Bureau; Roche: Consultancy, Honoraria, Other: Travel, Speakers Bureau; Servier: Consultancy; Gilead: Consultancy. Radford:AstraZeneca: Equity Ownership, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; ADC Therapeutics: Consultancy, Research Funding; GSK: Equity Ownership; Seattle Genetics: Consultancy, Honoraria. Patten:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria; Roche: Honoraria, Research Funding. O'Reilly:Kite Gilead: Honoraria. Bloor:Abvie, Gilead, Novartis, Autolus, Celgene, etc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational grant. Rowntree:Novartis: Consultancy. Bowles:Abbvie: Research Funding; Janssen: Research Funding. Collins:Gilead: Consultancy, Honoraria. McMillan:BMS: Honoraria; Celgene: Honoraria, Speakers Bureau; F. Hoffmann-La Roche Ltd: Honoraria, Speakers Bureau; Gilead: Honoraria; Novartis: Honoraria; Sandoz: Honoraria; Pfizer: Honoraria, Research Funding; MSD: Honoraria.

Background UCART19 is a genetically modified T-cell product manufactured from non-HLA matched healthy donor cells. Lentiviral-transduced CAR T-cells express (1) an anti-CD19 CAR (anti-CD19 scFv- 41BB- CD3ζ) and (2) an RQR8 "safety switch" that is intended to allow targeted elimination of RQR8+ cells by rituximab. UCART19 has been additionally modified to disrupt the T-cell receptor alpha constant (TRAC) and CD52 genes. The preliminary results of this "off-the-shelf" allogeneic CAR T-cell therapy in a phase I, dose-escalation trial of UCART19 in CD19+ R/R B-ALL adult patients (pts) are described. Methods The primary objective of this study is to determine the maximum tolerated dose of UCART19 by investigating up to four dose levels (DL) in separate sequential cohorts. Adult pts (age ≥16 years) with CD19+ R/R B-ALL who have exhausted available treatment options are eligible. Disease burden must be quantifiable morphologically or with a minimal residual disease (MRD) load ≥1x10-3 at the end of the last anti-leukemic treatment. The lymphodepletion regimen combines cyclophosphamide and fludarabine, with or without alemtuzumab (FC or FCA). A single dose of UCART19 is administered on Day 0, and pts are closely monitored for safety and anti-leukemic activity until the end of study, 3 months after UCART19 administration. Pts are then rolled-over into a 15-years long-term follow-up study. The dose escalation follows a modified Toxicity Probability Interval (mTPI) design based on the occurrence of dose-limiting toxicity (DLT) assessed at the end of the 28-day evaluation period post UCART19 (D28). Results As of 24 June 2017, the 2 first cohorts (3 pts each) who received the first DL (DL1=6x106 total CAR+ cells) have been completed. Median age was 22.5 years (range 18-42). Pts received 1 to 5 previous lines of treatment with 5 out of 6 pts having undergone an allogeneic stem cell transplant (allo-SCT). Four of them had relapsed within 4-6 months post-transplant. Prior to UCART19 infusion, 4 pts had low disease burden ( All pts experienced cytokine release syndrome (CRS): 1 G1, 4 G2 and 1 G4. CRS G1 and G2 were manageable by supportive care ± tocilizumab. CRS G4, assessed as a DLT, occurred in the context of neutropenic sepsis, and was considered to be a contributory factor in the patient's death from multiple organ failure at D15. Time to onset of first CRS symptoms ranged between D5 and D10. CRS correlated with serum cytokine increase (IL-6; IL-10 and INFγ) and UCART19 expansion in the blood. One patient was reported to have probable skin GvHD G1. Only G1 neurotoxic events were observed in 1 patient. Asymptomatic viral reactivations (CMV and/or adenovirus) were seen in 3 pts and resolved with antiviral therapy. Among the 6 pts, 4 achieved a CRi with MRD negativity at D28 (MRD-ve, defined as a tumor burden All 4 pts achieving MRD-ve remission underwent a subsequent allo-SCT, 3 of them within 3 months of UCART19 infusion and 1 following retreatment with FC lymphodepletion and the same dose of UCART19, this patient having relapsed with CD19+ disease 2 months post initial UCART19 infusion. Post allo-SCT, 1 patient relapsed at 100 days with CD19+ disease, 1 died from infection and 2 remain in complete remission. Three pts remain alive at 2.4, 5.3 and 10.2 months respectively post UCART19 treatment. UCART19 (both cells and transgene levels) peaked between D12 and D17 in blood (flow cytometry [figure 1] and qPCR, respectively). UCART19 was detectable in blood from D10 to D28 (up to D42 in 1 patient) and in BM aspirates performed at D14 and D28. In-vivo cell expansion in BM occurred in all but the refractory patient. Conclusion Preliminary results of this first-in-human trial of UCART19 treatment in a high risk R/R B-ALL adult population revealed no unexpected toxicities. Asymptomatic lymphodepletion-related viral reactivations and a probable skin GvHD G1 were encountered. CRi with MRD-ve was achieved in 4 out of 5 pts who reached D28. The 2 first cohorts treated at DL1 have been completed and DL2 will now be investigated on which further results may be presented. The study is active in the UK and will be expanded to other EU countries and the US (NCT 02746952). Disclosures Graham: Servier: Research Funding; Pfizer: Other: Educational meeting attendance; Gilead: Other: Educational meeting attendance; Sanofi: Other: Educational meeting attendance. Yallop: Jazz Pharmaceuticals: Honoraria; Amgen: Honoraria; Pfizer: Other: Advisory board. Jozwik: Servier: Research Funding. Patten: Gilead Inc: Honoraria, Research Funding; Roche: Honoraria; Abbvie: Honoraria. Ellard: Moldmed: Honoraria. Potter: Pfizer: Other: Advisory board; Jazz: Honoraria. Devereux: AbbVie: Consultancy, Honoraria; MSD: Consultancy, Honoraria; Roche: Consultancy, Other: travel expenses; GSK: Consultancy; Gilead: Consultancy, Honoraria, Other: travel expenses, Speakers Bureau; Janssen: Consultancy, Honoraria, Other: travel expenses, Speakers Bureau; Servier: Other: Advisory board. Pagliuca: Jazz: Honoraria; Merck: Honoraria, Research Funding; Bluebird: Honoraria; Pfizer: Honoraria; Basilea: Honoraria; Astellas: Consultancy, Speakers Bureau; Gilead: Honoraria. Zinai: Servier: Employment. Binlich: Servier: Employment. Dupouy: Servier: Employment. Philippe: Servier: Employment. Balandraud: Servier: Employment. Dubois: Servier: Employment. Konto: Bristol-Myers Squibb: Employment, Equity Ownership; Pfizer: Employment, Equity Ownership. Patel: Pfizer: Employment, Equity Ownership. Benjamin: Pfizer: Other: Participated in Adboard meeting, Research Funding; Servier: Research Funding; Celgene: Honoraria.

Abstract 3878 Poster Board III-814 Introduction Despite recent therapeutic improvements in the management of myeloma it remains an incurable disease. New therapies are therefore required. Pomalidomide (POM, Celgene) is a thalidomide derived immunomodulatory agent with similar preclinical spectrum of activity as lenalidomide. In Phase 1 studies we have previously demonstrated that POM monotherapy is well tolerated by patients with relapsed myeloma determining a maximum tolerated dose of 2mg od or 5mg on alternate days (Schey et al. JCO 2004; Streetly et al. BJHaem 2008). The toxicity profile was acceptable and overall response rates of 54 and 50% were observed with daily and alternate day dosing respectively. The current study examines long term responses, progression and survival outcomes. Patients were entered into the POM daily dosing or alternate day dosing Phase 1 studies between March 2001 and September 2003 and continued to receive treatment with POM until progressive disease (PD) or Grade 3 or greater non-haematological toxicity. Patients with PD were eligible to receive dexamethasone in addition to POM. POM became unavailable in May 2005 and patients still receiving drug were switched to receive lenalidomide. All patients gave informed consent. Results 44 patients received treatment with POM at a dose of 1mg alternate days – 10mg od. A median of 3 (range 1 – 8) prior lines of therapy had been received. POM was received for a median of 9.3 months (1 – 53). Following POM withdrawal 8/44 patients who had not developed PD subsequently received lenalidomide from a median of 30 months after starting POM. Overall responses by IMWG criteria to POM monotherapy were: CR 13.6%, VGPR 4.5%, PR 34%, MR 9%, SD 29.5% and PD 7% giving an overall response rate (>PR) of 52%. Dexamethasone was introduced for PD for 10 patients and prolonged SD for 1 patient. 5/10 of these patients had >MR response to the addition of dexamethasone. With a median follow-up of 28 months the median PFS was 13.7 months and median OS was 28 months. Patients who had a PR response or better received POM for a median of 17.5 months and had improved PFS (median 19.8 months) and OS (median 42 months). 8/44 patients subsequently received lenalidomide. 7/8 of these patients have now developed PD at a median 26 months from commencing lenalidomide and 74 months from starting POM. Conclusions POM is a very well tolerated drug with excellent long term responses observed in this Phase 1/2 setting predominantly as monotherapy. Phase 2 studies are ongoing and results of these are awaited with interest. Disclosures: Streetly: Celgene: Honoraria. Schey:Celgene: Honoraria.