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Introduction: One of the main complications of adoptive T cell therapy (ACT) is the en-masse activation of tumor-reactive T cells inducing a large release of cytokines followed by activation of other immune cells leading to adverse events. These are classified as a cytokine release syndrome (CRS) or neurotoxicity described as a CAR T Related Encephalopathy Syndrome (CRES). Several biomarkers have been associated with CRS and/or neurotoxicity such as LDH, ferritin and CRP. Cytokines have also been associated with CRS and and/or CRES, but present approaches rely on retrospective study of collected biomarkers. Here, we report the results of cytokine analysis using a point of care (POC) device to predict immune-related toxicities in patients with relapsed/refractory (R/R)DLBCL treated with axicabtagene ciloleucel (axi-cel). Methods: Patients with R/R DLBCL treated with commercial axi-cel were included in this study. Baseline serum samples were collected prior to lymphodepleting chemotherapy and then daily during hospitalization. To select which cytokines to monitor, we retrospectively analyzed 38 serum cytokines in a cohort of 53 patients with R/R B cell acute lymphoblastic leukemia (B-ALL) who were treated with 19-28z CAR T cells. The patients were divided into those requiring treatment with tocilizumab and/or steroids versus those who did not require treatment. We observed several cytokines, including IL-2, IL-6, IL-15 and IFNg, which were significantly elevated in patients with CRS and/or CRES requiring treatment (Figure 1a). Based on this analysis and results of published studies, eight serum proteins were selected in our study including IL-1b, IL-2, IL-6, IL-15, IFNg, TNFa, and angiopoietin-1 &2. We monitored these proteins using a POC device that allows for rapid daily monitoring with a turnaround time of two hours. We established that the results from the POC device strongly correlate with a current gold standard device(Luminex), which has a typical two day turn around time. CRS and CRES were prospectively graded using revised Lee criteria (Lee et al Blood 2014) and the CARTOX group (Neelapu et al. NRCO 2017) respectively by an experienced clinical team and confirmed by chart review retrospectively. Results: A total of 20 patients with R/R DLBCL treated with commercial axi-cel were identified. Median age 64 years ( range 43-73) with 80% male.In our cohort, grades 1-3 CRS were observed in 45%, 40% and 5% respectively. There were no observed grade 0 or grade 4 CRS. There were two patients (10%) who died in the setting of severe toxicity. Patients with grade 5 CRS had higher levels of IL-6 and angiopoietin 2/angiopoietin 1 ratio at day one, which correlated with severity of toxicity r=0.52 (p= 0.039) , and r=0.53 (p=0.033) respectively (Fig. 1b). Furthermore, patients with high grades CRS had elevated levels of IL-15 at day seven (r=0.83, p=0.006). The majority of patients (55%) had grade 1-2 CRES.There were no significant correlations between serum cytokine levels and CRES or between those who required tocilizumab/steroids vs. those who did not, likely due to the small sample size. In select cases, daily monitoring of cytokines using the POC device provided clinical insight that wasn't evident from standard biomarkers. For example, one patient who developed delayed CRS had high serum levels of IL-6 but did not have elevated levels of CRP(Fig.1c). Discussion: In this analysis of 20 patients, we observed a correlation between severe CRS and elevated serum cytokine levels of IL-6 and angiopoietin 2/angiopoietin 1 ratio at day one suggesting that these biomarkers may be utilized to predict severe toxicity in patients treated with ACT. While this study is limited by small sample size, our observations correlate with previously published biomarkers data in patients enrolled in clinical trials. To our knowledge this is the first reported cytokine data using commercial axi-cel. Monitoring of cytokines using a POC device is feasible and will be useful clinically. High risk patients may be identified early and help guide intervention in real time, for example day one elevated IL-6 levels might inform earlier use of tocilizumab. We continue to enroll patients to validate cytokines as predictive biomarkers with the goal of informing the development of preventative strategies to mitigate CAR T cell therapy immune related adverse events. Disclosures Locke: Cellular BioMedicine Group Inc.: Consultancy; Kite Pharma: Other: Scientific Advisor; Novartis Pharmaceuticals: Other: Scientific Advisor. Brentjens:Juno Therapeutics, a Celgene Company: Consultancy, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Park:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy; Kite Pharma: Consultancy; Juno Therapeutics: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Novartis: Consultancy; Pfizer: Consultancy; Shire: Consultancy. Davila:Celyad: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Background: Relapsed adult acute lymphoblastic leukemia (ALL) is associated with high reinduction mortality, chemotherapy resistance, and dismal prognosis with a median overall survival (OS) < 6 months and 5-year OS ≤10%. We have previously reported a high anti-tumor activity of autologous T cells genetically modified to express 19-28z chimeric antigen receptor (19-28z CAR) targeting CD19 in adult patients with CLL and ALL (Brentjens R et al. Blood 2011; Davila M et al. Sci Transl Med2014). Herein, for the first time, we further report the long-term outcome of our phase I clinical trial in adults with relapsed/refractory (R/R) ALL (NCT01044069) with analysis on potential predictive markers of response and neurological toxicities. Patients and Methods: Adult patients with R/R B-ALL were enrolled. Eligible patients underwent leukapheresis, and 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). All patients received lymphodepleting chemotherapy followed 2 days later by 1x106 – 3x10619-28z CAR T cells/kg. The primary objective of the study was to evaluate the safety and anti-tumor activity of 19-28z CAR T cells in ALL. Post-treatment minimal residual disease (MRD) was assessed at day 14-28 by multiparameter flow cytometry and deep sequencing in the bone marrow (BM) samples (Adaptive Biotech Corp.) Results: 24 patients have been treated. The median age was 56 years (range, 23-74). 6 patients (25%) had Ph+ B-ALL (T315I mutation in 2 patients), 6 patients (25%) had prior allogeneic hematopoietic stem cell transplant (allo-HSCT), and 11 patients (46%) had 3 or more prior lines of ALL therapy before receiving the 19-28z CAR T cell therapy. Of the 24 patients, 22 patients were evaluable for response. At the time of 19-28z CAR T cell infusion, 12 of 22 patients had morphologic disease (6 to 97% blasts in the BM) and the remaining 10 patients had MRD. Twenty out of 22 patients (91%) were in complete remission (CR) after 19-28z CAR T-cell infusion, and 18 of these 20 patients (90%) achieved an MRD-negative CR. Ten of the 13 transplant eligible patients (77%) successfully underwent allo-HSCT following the 19-28z CAR T cell therapy. As of July 1, 2014, the median follow-up was 7.4 months (range 1-34), with 13 patients having at least 6 months of follow-up. Responses appear durable with 6 patients remaining disease-free beyond 1 year (range 12.6 – 34 months). Median overall survial (OS) is 9 months. 5 patients relapsed during the follow-up, including 1 patient with CD19 negative relapse. Three of the relapsed patients were treated again with the 19-28z CAR T cells, and two patients achieved a second CR. Comparing responders to non-responders, no association was observed between response and age ( While none of the 10 patients with MRD at the time of T cell infusion developed cytokine release syndrome (CRS), 9 of 13 patients with morphologic disease at the time of the T cell infusion developed CRS with or without neurological symptoms that required intervention with an IL-6R antagonist or corticosteroid. A detailed analysis of serum cytokines demonstrated a consistent peak of IL-6 (22.2 to 553-fold increase) immediately prior to the development of neurological toxicities. Based on these data, we have developed a multi-disciplinary CRS management algorithm for patients at high risk in order to reduce the severity of CRS and improve safety of the 19-28z CAR T cell therapy. Conclusions: While longer follow-up is needed to confirm the durability of the observed responses, the potent induction of MRD-negative responses and successful long-term outcomes, including subsequent allo-HSCT without apparent additional post-transplant toxicities, strongly support the use of 19-28z CAR T cells in adult patients with B-ALL. A temporal relationship between serum IL-6 levels and neurological toxicities indicates that early intervention with IL-6 directed therapy may be more effective in ameliorating neurological toxicities in patients with morphologic disease at the time of T-cell infusion. These findings will need to be evaluated systematically and confirmed in a larger phase 2 trial. Disclosures Park: Juno Therapeutics: Research Funding. Riviere: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 and Stock holder Other.

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. Figure 1 Figure 1. Disclosures Riviere: 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.

Although most adults diagnosed with B-ALL can be induced into a first complete remission (CR1 rates of approximately 80-90%), a majority will relapse and develop chemorefractory disease. Novel, non-chemotherapy based treatments are needed for this group of patients. We have developed a novel CD19-targeted T cell-based therapy for patients with B cell malignancies. We isolate T cells from patients with relapsed/refractory B-ALL and genetically modify them with a chimeric antigen receptor (CAR) construct, termed 19-28z, which comprises a CD19 binding domain fused to the signaling domains of the CD28 costimulatory receptor and the ζ chain of the CD3 complex. CD19 is a universal B cell antigen expressed on all normal and malignant B cells. Expression of the 19-28z CAR by a T cell promotes binding of the CD19 antigen and triggers cytotoxicity, cytokine release and proliferation upon engagement of CD19. We are conducting a Phase I clinical protocol in adults with relapsed/refractory B-ALL (NCT01044069). Enrolled patients are leukapheresed and then re-induced with salvage chemotherapy. A T cell infusion (3 x 106 19-28z CAR T cells/kg) is administered following conditioning chemotherapy. We now describe the results from this Phase I protocol. Thirteen adults have been treated to date: eleven were enrolled with relapsed/refractory disease, while the other 2 were enrolled and leukapheresed during CR1, but not treated until they relapsed. The age of the patients ranged from 23 to 74 with a median age of 42. Three of the 13 patients had Philadelphia-chromosome positive B-ALL, which is considered the most negative genetic risk factor for adults with B-ALL. We were able to achieve the required T cell dose, despite collecting patients with high blast counts or marked lymphopenias, in all but one patient. Seven of the 13 patients were infused with 19-28z CAR T cells while they had gross residual disease (>5 to 70% blasts in the BM). The remaining patients had MRD, detected by flow cytometry or deep sequencing, at the time of 19-28z CAR T cell infusion. Six patients developed toxicities including high-grade fevers (>40°C), hypotension, hypoxia, mental status changes, and seizures. These episodes ran for approximately one week before they were halted by treatment with steroids or tocilizumab. The other 7 patients did not experience toxicities. All patients completely recovered and were able to leave the hospital. The occurrence of toxicities correlated with tumor burden so that patients with gross residual disease (>5% blasts in BM) developed toxicities, while patients with MRD had no evidence of toxicities. Ten out of the 12 patients with detectable disease before T cell infusion developed MRD- responses such that 5 of the patients with gross residual disease (blasts > 5% in BM) became MRD- and 5 MRD+ patients became MRD-. The rapidity of the responses was quite remarkable with MRD- results obtained as early as 7 -14 days after T cell infusion. Furthermore, despite the poor predicted outcomes of relapsed Ph+ B-ALL we were able to get these patients MRD-, as detected by both deep sequencing for the IgH rearrangement and qPCR for the bcr-abl transcript. Conclusion The potent induction of MRD- responses and the reversibility of toxicities occurring in a subset of patients strongly support integrating this therapy in the modern paradigm for B-ALL therapy, by facilitating access to allogeneic-stem cell transplantation (SCT) for patients with relapsed B-ALL. Indeed, out of the 13 patients treated to date, 4 underwent an allo-SCT and 5 are being prepared for an allo-SCT. Of the remaining 4 patients, 1 is a non-responder (a patient with extramedullary disease, but no disease in the bone marrow), 1 relapsed (not eligible for allo-SCT), 1 is in CR2 (medically not eligible for allo-SCT), and 1 has not been evaluated for treatment response yet. Overall, the results from this Phase I protocol demonstrate that toxicities associated with this therapy are predictable and manageable. Furthermore, the remarkable MRD- re-induction rate and facilitation for allo-SCT we report here warrant further evaluation of this therapy in a Phase II protocol. Disclosures: No relevant conflicts of interest to declare.