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BACKGROUND. T cells that have been modified to express a CD19-specific chimeric antigen receptor (CAR) have antitumor activity in B cell malignancies; however, identification of the factors that determine toxicity and efficacy of these T cells has been challenging in prior studies in which phenotypically heterogeneous CAR–T cell products were prepared from unselected T cells. METHODS. We conducted a clinical trial to evaluate CD19 CAR–T cells that were manufactured from defined CD4+ and CD8+ T cell subsets and administered in a defined CD4+:CD8+ composition to adults with B cell acute lymphoblastic leukemia after lymphodepletion chemotherapy. RESULTS. The defined composition product was remarkably potent, as 27 of 29 patients (93%) achieved BM remission, as determined by flow cytometry. We established that high CAR–T cell doses and tumor burden increase the risks of severe cytokine release syndrome and neurotoxicity. Moreover, we identified serum biomarkers that allow testing of early intervention strategies in patients at the highest risk of toxicity. Risk-stratified CAR–T cell dosing based on BM disease burden decreased toxicity. CD8+ T cell–mediated anti-CAR transgene product immune responses developed after CAR–T cell infusion in some patients, limited CAR–T cell persistence, and increased relapse risk. Addition of fludarabine to the lymphodepletion regimen improved CAR–T cell persistence and disease-free survival. CONCLUSION. Immunotherapy with a CAR–T cell product of defined composition enabled identification of factors that correlated with CAR–T cell expansion, persistence, and toxicity and facilitated design of lymphodepletion and CAR–T cell dosing strategies that mitigated toxicity and improved disease-free survival. TRIAL REGISTRATION. ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01865617","term_id":"NCT01865617"}}NCT01865617. FUNDING. R01-CA136551; Life Science Development Fund; Juno Therapeutics; Bezos Family Foundation.

Oxidative stress has been implicated in the development of nonalcoholic fatty liver disease (NAFLD) and progression to the more severe form, nonalcoholic steatohepatitis (NASH), in children. We aimed to study the clinical correlation between bilirubin, a potent endogenous antioxidant with cytoprotective properties, and histopathological findings in pediatric patients with NAFLD.We included consecutive children with biopsy-proven NAFLD and obtained demographic, clinical, and histopathological data. We performed logistic regression analysis to assess the clinical factors associated with the histological features of NASH or fibrosis.From a total of 302 biopsies, 67% (203) had evidence of NASH, whereas 64.2% had some degree of fibrosis (stage 1 in 51%, stage 2 in 6.3%, and stage 3 in 6.6%). Mean total bilirubin was significantly lower in the NASH group compared with the non-NASH group (0.65 ± 0.24 vs 0.73 ± 0.22 mg/dL, P = 0.007). Higher total bilirubin levels were negatively correlated with the presence of steatosis and the NAFLD activity score (P0.05), whereas a trend in that direction was observed for presence of fibrosis and inflammation (P = 0.051). On multivariable analysis, higher bilirubin levels were significantly associated with a decreased likelihood of a histological diagnosis of NASH on biopsy (odds ratio 0.29, 95% CI 0.10-0.85, P = 0.024).In children with NAFLD, there is an inverse relation between serum bilirubin levels and the presence of NASH on biopsy. This may be secondary to the antioxidant effect of bilirubin.

BACKGROUND: Chemotherapy followed by autologous T cells that are genetically modified to express a CD19-specific chimeric antigen receptor (CAR) has shown promise as a novel therapy for patients with relapsed or refractory B cell acute lymphoblastic leukemia (B-ALL); however, the risk of severe cytokine release syndrome (sCRS) and neurotoxicity has tempered enthusiasm for widespread application of this approach. The functional heterogeneity that is inherent in CAR-T cell products that are manufactured from undefined T cell subsets has hindered definition of dose-response relationships and identification of factors that may impact efficacy and toxicity. METHODS: We are conducting the first clinical trial that administers CD19 CAR-T cells manufactured from a defined composition of T cell subsets to adults with relapsed or refractory B-ALL. CD8+ and CD4+ T cells were enriched from each patient, transduced with a CD19 CAR lentivirus and separately expanded in vitro before formulation for infusion in a 1:1 ratio of CD8+:CD4+ CAR+ T cells at 2x105, 2x106 or 2x107 CAR-T cells/kg. Prior to CAR-T cell infusion, patients underwent lymphodepletion with a high-dose cyclophosphamide (Cy)-based regimen with or without fludarabine (Flu). RESULTS: Twenty-nine adults with B-ALL (median age 40, range 22 - 73 years; median 17% marrow blasts, range 0 - 97%), including 10 patients who had relapsed after allogeneic transplantation, received at least one CAR-T cell infusion. Twenty-four of 26 restaged patients (92%) achieved bone marrow (BM) complete remission (CR) by flow cytometry. CD4+ and CD8+ CAR-T cells expanded in vivo after infusion and their number in blood correlated with the infused CAR-T cell dose. Thirteen patients received lymphodepletion with Cy-based regimens without Flu. Ten of 12 restaged patients (83%) achieved BM CR by flow cytometry; however, 7 of these (70%) relapsed a median of 66 days after CAR-T cell infusion. Disease relapse correlated with a loss of CAR-T cell persistence in blood. We observed a CD8 cytotoxic T cell response to the murine scFv component of the CAR transgene that contributed to CAR-T cell rejection, and resulted in lack of CAR-T cell expansion after a second CAR-T cell infusion in 5 patients treated for persistent or relapsed disease. To minimize immune-mediated CAR-T cell rejection 14 patients were treated with Cy followed by Flu lymphodepletion (Cy/Flu, Cy 60 mg/kg x 1 and Flu 25 mg/m2 x 3-5) before CAR-T cell infusion. All patients (100%) who received Cy/Flu lymphodepletion achieved BM CR after CAR-T cell infusion. CAR-T cell expansion and persistence in blood was higher in Cy/Flu-lymphodepleted patients compared to their counterparts who received Cy alone (Day 28 after 2x106 CAR-T cells/kg: CD8+ CAR-T cells, mean 55.8/μL vs 0.10/μL, p CAR-T cell infusion was associated with sCRS, characterized by fever and hypotension requiring intensive care in 7 of 27 patients (26%) and neurotoxicity (≥ grade 3 CTCAE v4.03) in 13 of 27 patients (48%). Two patients died following complications of sCRS. Patients with sCRS or neurotoxicity had higher peak serum levels of IL-6, IFN-γ, ferritin and C-reactive protein compared to those without serious toxicity. Importantly IL-6, IFN-γ and TNF-α levels in serum collected on day 1 after CAR-T cell infusion from those who subsequently developed neurotoxicity were higher than those collected from their counterparts who did not develop neurotoxicity (IL-6, p CONCLUSION: Risk-stratified dosing of CD19 CAR-T cells of defined subset composition is feasible and safe in a majority of patients with refractory B-ALL, and results in a CR rate of 92%. Addition of Flu to Cy-based lymphodepletion improves CAR-T cell expansion, persistence and DFS. Disclosures Turtle: Juno Therapeutics: Patents & Royalties, Research Funding. Berger:Juno Therapeutics: Patents & Royalties. Jensen:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding. Riddell:Adaptive Biotechnologies: Consultancy; Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Cell Medica: Membership on an entity's Board of Directors or advisory committees. Maloney:Seattle Genetics: Honoraria; Janssen Scientific Affairs: Honoraria; Roche/Genentech: Honoraria; Juno Therapeutics: Research Funding.

BACKGROUND: Autologous T cells genetically modified to express a CD19-specific chimeric antigen receptor (CAR) have demonstrated activity in patients with relapsed or refractory B cell NHL and CLL. The functional heterogeneity that is inherent in CAR-T cell products that are manufactured from undefined T cell subsets has hindered definition of dose-response relationships and identification of factors that may impact efficacy and toxicity, such as the lymphodepletion regimen and infused cell dose. We manufactured anti-CD19 CAR-T cells from a defined composition of CD4+ and CD8+ T cell subsets to treat adults with relapsed or refractory B cell NHL or CLL. T cell subsets were enriched from each patient, transduced with a CD19 CAR lentivirus and separately expanded in vitro before formulation for infusion in a 1:1 ratio of CD8+:CD4+ CAR+ T cells at one of three dose levels (2x105, 2x106 or 2x107 CAR-T cells/kg). CAR-T cells were administered 48-96 hours after lymphodepletion with either cyclophosphamide (Cy, 60 mg/kg)+/- etoposide or Cy (60 mg/kg) and fludarabine (25 mg/m2 daily for 3-5 days (Cy/Flu). RESULTS: Adult patients with relapsed/refractory CD19 expressing B cell NHL (n=28, median age 59 years, range 36-70) or CLL (n=6, median age 60 years, range 54-64) were treated with at least one CAR-T cell infusion. NHL histologies include diffuse large B cell or transformed NHL (DLBCL, n=18), follicular NHL (FL, n= 6) or mantle cell lymphoma (MCL, n=4). 15 patients had failed prior autologous (n=13) or allogeneic (n=3) transplants. Twelve of the 28 NHL patients received lymphodepletion with Cy-based regimens without fludarabine. Expansion of CAR-T cells and clinical responses were observed in 50% (CR=1 (DLBCL), PR=5 (2 FL, 2 DLBCL, 1 MCL), no response=6). Patients were treated at all three dose levels without dose limiting toxicity or severe cytokine release syndrome (sCRS). With this regimen, we observed short CAR-T cell persistence in most patients and demonstrated a CD8-mediated immune response to the murine scFv component of the CAR transgene that correlated with loss of CAR-T cells. Retreatment with CAR-T cells with or without chemotherapy in 5 patients led to no significant T cell expansion or clinical responses. To minimize transgene rejection fludarabine was added to the lymphodepletion regimen administered to the subsequent 16 NHL patients. Clinical responses were evaluated in 12 of 16 patients (2 not yet evaluable, 2 early deaths). Addition of Flu to the lymphodepletion regimen increased the CR rate to 42%, compared to 8% with Cy alone. Clinical responses were identified in 6 of 8 patients with DLBCL (3 CR, 3 PR) and 2 of 3 patients with FL (2 CR). The overall response rate was 67%. We noted higher peak CAR-T cell levels in blood in the Cy/Flu group (n=13) compared with the Cy only group (n=11) (CD8+ CAR-T cells, median 31.9 cells/ml vs 0.55 cells/ml, p = 0.009; CD4+ CAR-T cells, median 16.5 cells/ml vs 0.31 cells/ml, p= 0.007), and CAR-T cell persistence was longer in Flu-treated patients (see Figure 1 for patients treated at 2 x 107/kg). Surprisingly, 2 of 7 patients who received 2 x 107 CAR-T cells/kg experienced dose-limiting toxicity necessitating dose de-escalation. Markedly elevated IL-6 levels were observed within the first day after CAR-T cell infusion in patients who subsequently developed severe toxicity, which may provide an opportunity to test early interventional approaches to minimize toxicity. Six patients with relapsed and refractory CLL received CAR-T cells. Five of 6 restaged patients had complete clearance of blood and/or marrow disease by high-resolution flow cytometry 4 weeks following treatment. Overall clinical responses included 3 CR, 1 PR and 2 no response. One patient with a PR died from refractory pulmonary aspergillus infection. Patients with CR remain in remission at 1-10 months after therapy. CONCLUSION: Immunotherapy with CD19 CAR-T cells of defined subset composition is feasible in patients with NHL and CLL and has potent anti-tumor activity. Toxicity is related to cell dose. The addition of Flu to a Cy-based lymphodepletion regimen results in greater CAR-T cell expansion and persistence, and improves the CR rate after CD19 CAR-T cell therapy. Disclosures Turtle: Juno Therapeutics: Patents & Royalties, Research Funding. Berger:Juno Therapeutics: Patents & Royalties. Jensen:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding. Riddell:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding; Cell Medica: Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy. Maloney:Juno Therapeutics: Research Funding; Janssen Scientific Affairs: Honoraria; Seattle Genetics: Honoraria; Roche/Genentech: Honoraria.

3006 Background: Genetically modified T cells derived from distinct T cell subsets differ in the capacity to persist after adoptive transfer. We are conducting the first phase I/II clinical trial in which patients (pts) with CD19+ B cell malignancies receive T cells comprised of a defined composition of CD8+ TCM and CD4+ T cells engineered to express a CD19 CAR. Methods: CD8+ TCM and CD4+ T cells were separately enriched from each patient, transduced with a CD19 CAR lentivirus and expanded in vitro. The cell product for infusion was formulated in a 1:1 ratio of CD8+:CD4+ CAR+ T cells and infused at one of three dose levels (2x105 – 2x107 CAR-T cells/kg) after lymphodepleting chemotherapy. Results: Thirty-seven pts with ALL (n = 20), NHL (n = 14) or CLL (n = 3) have been treated and 33/37 received a product that conformed to a prescribed CD8+:CD4+ composition. There was no serious acute infusional toxicity. Severe cytokine release syndrome (sCRS) consisting of fever, hypotension, coagulopathy and neurotoxi...