19-28z Chimeric Antigen Receptor Research Articles

Overexpression of Rorγt in CAR T Cells Improves Persistence and Reduces Exhaustion

Although T cells modified with a chimeric antigen receptor (CAR) are highly effective, durability of remissions may be limited by the poor persistence of adoptively transferred CAR T cells in patients. Growing evidence supports the idea that the pre-infusion phenotype of CAR T cells affects the efficacy of CAR T cell therapies, in part due to the increased ability of certain subsets of CAR T cells to persist long-term. Studies using conventional T cells have suggested that adoptive transfer of T cells programmed to have Th17/Tc17 effector functions can increase the anti-tumor efficacy and persistence of transferred cells when compared to adoptive transfer of non-Th17/Tc17 cells. However, standard CAR formats currently in clinical use that contain either a CD28 or 4-1BB costimulatory domain fail to generate substantial numbers of Th17/Tc17-like cells. Thus, few studies have investigated whether Th17/Tc17 CAR T cells could enhance the efficacy of CAR T cell therapies.We generated a multi-cistronic lentiviral construct encoding ROR-related Orphan Receptor gamma (RORγt), a key lineage-specifying transcription factor involved in Th17/Tc17 differentiation, followed by a murine CAR targeting CD19 that contains a CD28 costimulatory domain (1928z). RORγt expression did not hinder degranulation in response to CAR antigen upon co-culture with E2aPbx, a murine acute lymphoblastic leukemia cell line. Significantly higher numbers of RORγt-1928z CAR T cells produce IL-17 compared to 1928z CAR T cells (p<0.0001) suggesting that RORγt expression is sufficient to program type-17 effector functions in CAR T cells.To determine the impact of RORγt overexpression on CAR T cell phenotype and persistence in vivo, we adoptively transferred 1x10 6 1928z or RORγt-1928z CAR T cells into leukemia-bearing C57Bl6/J recipients and analyzed CAR T cells from the bone marrow at days 4, 11, and 31. As early as day 4 post-transfer, RORγt-1928z CAR T cells were present at significantly higher numbers than 1928z CAR T cells, and remained higher through Day 31 (0.16% of the bone marrow for 1928z CAR T cells vs 0.84% of the bone marrow for RORγt-1928z CARs; p= 0.0012, n=5 mice per group. The RORγt-1928z CAR T cells were enriched for an effector/effector memory phenotype (CD62L-) compared to 1928z CAR T cells, which were mostly of a central memory phenotype (CD62L+). Interestingly, the RORγt-1928z CAR T cells were enriched for IL-7Rα+ cells and expressed more IL7Rα than their 1928z CAR T cell counterparts (p=0.0012), suggesting an increased capacity for self-renewal in RORγt-1928z CAR T cells.Previous work from our lab has demonstrated that CAR T cells that persist after leukemia clearance have an exhausted phenotype, with increased expression of PD1 and a reduced functionality 1. After leukemia clearance, RORγt-1928z CAR T cells expressed lower levels of PD1 than their 1928z counterparts (p<0.0001). Finally, 1928z CAR T cells form a population of Eomes hiPD1 hi cells, associated with terminal exhaustion, that is absent in the RORγt-1928z CAR T cells.Taken together, our preliminary data demonstrates that overexpression of RORγt is sufficient to program type-17 effector functions in CAR T cells and suggests that RORγt overexpression can enhance the ability of CAR T cells to persist and self-renew, and prevent terminal exhaustion. RORγt overexpression may enhance persistence of CAR T cells and durability of remissions in hematologic malignancies. Furthermore, RORγt overexpression may also be a strategy to enhance CAR T cell efficacy against solid tumors, where an immunosuppressive microenvironment contributes to T cell dysfunction.1.Yinmeng Yang, Mark Eric Kohler, Terry J. Fry; Effect of Chronic Endogenous Antigen Stimulation on CAR T Cell Persistence and Memory Formation. Blood2017; 130 (Supplement 1): 166. doi: https://doi.org/10.1182/blood.V130.Suppl_1.166.16 DisclosuresFry: Sana Biotechnology: Current Employment, Current equity holder in publicly-traded company.

Modified EASIX predicts severe cytokine release syndrome and neurotoxicity after chimeric antigen receptor T cells

AbstractPatients who develop chimeric antigen receptor (CAR) T-cell–related severe cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome (ICANS) exhibit hemodynamic instability and endothelial activation. The EASIX (Endothelial Activation and Stress Index) score (lactate dehydrogenase [LDH; U/L] × creatinine [mg/dL]/platelets [PLTs; 109 cells/L]) is a marker of endothelial damage that correlates with outcomes in allogeneic hematopoietic cell transplantation. Elevated LDH and low PLTs have been associated with severe CRS and ICANS, as has C-reactive protein (CRP), while increased creatinine is seen only in a minority of advanced severe CRS cases. We hypothesized that EASIX and 2 new modified EASIX formulas (simplified EASIX, which excludes creatinine, and modified EASIX [m-EASIX], which replaces creatinine with CRP [mg/dL]), calculated peri-CAR T-cell infusion, would be associated with development of severe (grade ≥ 3) CRS and ICANS. We included 118 adults, 53 with B-acute lymphoblastic leukemia treated with 1928z CAR T cells (NCT01044069) and 65 with diffuse large B-cell lymphoma treated with axicabtagene ciloleucel or tisagenlecleucel. The 3 formulas showed similar predictive power for severe CRS and ICANS. However, low PLTs and high CRP values were the only variables individually correlated with these toxicities. Moreover, only m-EASIX was a significant predictor of disease response. m-EASIX could discriminate patients who subsequently developed severe CRS preceding the onset of severe symptoms (area under the curve [AUC] at lymphodepletion, 80.4%; at day −1, 73.0%; and at day +1, 75.4%). At day +3, it also had high discriminatory ability for severe ICANS (AUC, 73%). We propose m-EASIX as a clinical tool to potentially guide individualized management of patients at higher risk for severe CAR T-cell–related toxicities.

Comparing CAR T-cell toxicity grading systems: application of the ASTCT grading system and implications for management

AbstractVarious grading systems are currently used for chimeric antigen receptor (CAR) T-cell–related toxicity, cytokine release syndrome (CRS), and immune effector cell–associated neurotoxicity syndrome (ICANS). We compared the recently proposed American Society for Transplantation and Cellular Therapy (ASTCT) grading system to other grading scores in 2 populations of adults: patients (n = 53) with B-cell acute lymphoblastic leukemia (B-ALL) treated with 1928z CAR T-cells (clinicaltrials.gov #NCT01044069), and patients (n = 49) with diffuse large B-cell lymphoma (DLBCL) treated with axicabtagene-ciloleucel (axi-cel) or tisagenlecleucel after US Food and Drug Administration approval. According to ASTCT grading, 82% of patients had CRS, 87% in the B-ALL and 77% in the DLBCL groups (axi-cel: 86%, tisagenlecleucel: 54%), whereas 50% of patients experienced ICANS, 55% in the B-ALL and 45% in the DLBCL groups (axi-cel: 55%, tisagenlecleucel: 15%). All grading systems agreed on CRS and ICANS diagnosis in 99% and 91% of cases, respectively. However, when analyzed grade by grade, only 25% and 54% of patients had the same grade in each system for CRS and ICANS, respectively, as different systems score symptoms differently (upgrading or downgrading their severity), leading to inconsistent final grades. Investigation of possible management implications in DLBCL patients showed that different recommendations on tocilizumab and steroids across current guidelines potentially result in either overtreating or delaying treatment. Moreover, because these guidelines are based on single products and different grading systems, they cannot be universally applied. To avoid discrepancies in assessing and managing toxicities of different products, we propose that unified grading be used across clinical trials and in practice and that paired management guidelines with product-specific indications be developed.

Clinical Factors Associated with Improved Survival Following Allogeneic HSCT after CD19 CAR Therapy in Adult Patients with Relapsed B-ALL

Introduction: Autologous chimeric antigen receptor (CAR) T cell therapy has shown to be effective in CD19+ relapsed or refractory (R/R) B-ALL patients (pts). However, relapses are common and the role of post-CAR allogeneic hematopoietic stem cell transplant (alloHSCT) remains unclear, particularly in adults with relapsed B-ALL. We previously reported that there was no survival benefit with post-CAR alloHSCT in overall adult ALL population (Park J et al. NEJM 2018), but it is unclear whether there is a subset of pts who may benefit the most from post-CAR alloHSCT. Therefore, we sought to identify clinical features that are associated with a better long-term survival in adult B-ALL pts treated with CD19 CAR T cells followed by alloHSCT. Methods: We performed a retrospective chart review of adult pts with R/R ALL treated with 19-28z CAR T therapy at MSKCC (NCT01044069), with a particular focus on pts who achieved minimal residual disease (MRD) negative CR to the CAR therapy and subsequently proceeded to alloHSCT. Clinical data was updated with the data cutoff date of July 15, 2019. We examined the association between overall survival and the following clinical factors: impact of age, prior HSCT status, presence of Philadelphia chromosome (Ph), disease status at the time of CAR therapy (MRD vs. morphologic), severity of cytokine release syndrome (CRS) and neurotoxicity (NTX) experienced during CAR therapy. Survival was calculated from the time of CAR T cell infusion. Continuous variables were analyzed univariately using cox PH models. Categorical variables were analyzed using Kaplan Meier methodology and log rank tests. Results: Of the 53 pts who received 1928z CAR T cells, 16 pts proceeded to alloHSCT after achieving MRD negative CR to the CAR therapy. The median age of these pts was 38 (range, 23-66), and baseline disease and pt characteristics as well as response and toxicity to CAR T therapy are listed in Table 1. Of the 16 pts, 6 pts remain alive in remission; 4 pts died of relapse (median time to relapse: 104.5 days, 57-194), and 6 pts died of transplant-related mortality (TRM) in remission (n=4, infection; n=1, pulmonary VOD; n=1, respiratory failure of unclear etiology). Detailed disease and treatment characteristics by the outcome categories are listed in Table 2. For those pts who are alive in remission, the median survival is 47.5 months (range, 39.7-92.4). Among the examined clinical variables, we found younger age and no severe NTX (i.e. grade 0-2) after CAR therapy to be significantly associated with improved overall survival (p=0.014 and 0.05, respectively) but prior lines of therapy, time to HSCT, prior HSCT, Ph chromosome, disease status at the time of T cell therapy and severity of CRS did not impact the survival after alloHSCT. Conclusions: In this retrospective analysis, we found that younger age and no severe NTX to CD19 CAR therapy were associated with improved overall survival following alloHSCT. Number of relapses following alloHSCT (4 of 16 pts) appears to be lower compared to the previously reported number of relapse in the adult ALL cohort without alloHSCT (17 of 26 pts). However, the occurrence of TRM due to infection is high, likely a reflection of heavily pretreated pt population and possibly further immunosuppression from CAR + alloHSCT. The link between severe NTX and worse survival is unclear but could be related to prolonged corticosteroid use and high disease burden. While no definitive conclusion can be drawn due to a small sample size, our data suggests a certain subset of adult pts with R/R B-ALL may benefit more from alloHSCT as a consolidation therapy following CD19 CAR T cells, and acute and late infectious complications following alloHSCT should be carefully monitored. These findings should be validated prospectively and compared between different CAR constructs. Disclosures Park: Allogene: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Autolus: Consultancy; GSK: Consultancy; Incyte: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Riviere:Fate Therapeutics: Consultancy; Juno Therapeutics: Consultancy, Equity Ownership, Research Funding; Memorial Sloan Kettering Cancer Center: Employment. Sadelain:Memorial Sloan Kettering Cancer Center: Employment; Fate Therapeutics: Consultancy, Patents &amp; Royalties; Juno Therapeutics: Consultancy, Patents &amp; Royalties, Research Funding. Brentjens:JUNO Therapeutics: Consultancy, Patents &amp; Royalties, Research Funding; Celgene: Consultancy.

Prediction of toxicity in R/R DLBCL treated with Axicabtagene Clioleucel (19-28z CAR T)

Abstract Background A cytokine release syndrome (CRS) or neurotoxicity described as a chimeric antigen receptor (CAR) T Related Encephalopathy Syndrome (CRES) is one of the main complications while CD19 CAR T has been successful in relapsed/refractory (R/R) B cell malignancies. CRS and/or CRES have been associated with standard biomarkers such as CRP and ferritin but also with cytokines. We report the results of cytokine analysis using a point of care (POC) device to predict immune-related toxicities in patients with R/R DLBCL treated with axicabtagene ciloleucel (axi-cel). Methods Patients treated with commercial axi-cel in Moffitt Cancer Center were included in this study. Serum samples were collected prior to lymphodepleting chemotherapy at baseline and then during hospitalization. Based on 38 serum cytokineś analysis in B-cell acute lymphoblastic leukemia patients treated with 19-28z CAR T and results of published studies, 8 serum proteins were selected to monitor. CRS and CRES were prospectively graded by Lee criteria and CARTOX respectively. Results 41 patients were identified. Median age was 64 years old (76% male). Non-severe (grade 0-2) and severe (grade 3-5) CRS were observed in 93% and 7% respectively while non-severe and severe CRES were observed in 71% and 29% respectively. 2 patients died in the setting of severe toxicity. Baseline CRP, ferritin, IL-6 levels were significantly elevated in the patients who developed severe CRS and/or CRES. Baseline angiopoietin-2/angipoietin-1 ratio (ANG-2/1) was also correlated with severe CRES. In select cases, monitoring of cytokines provided clinical insight that wasnt evident from standard biomarkers. Conclusions We observed correlations between severe toxicities and elevated serum cytokine levels of baseline IL-6 and ANG-2/1 suggesting that these biomarkers may be utilized to predict severe toxicity in patients treated with CAR T. Monitoring of cytokines using a POC device is feasible and would be useful clinically.

Impact of bridging chemotherapy on clinical outcome of CD19 CAR T therapy in adult ALL.

2520 Background: Autologous chimeric antigen receptor (CAR) T cell therapy has shown to be effective in CD19+ relapsed or refractory (R/R) B-ALL but requires a 2-4 week period of cell processing and manufacture. During this “bridging period,” patients are vulnerable to disease progression and complications. We sought to characterize bridging strategies in our published study of CD19 CAR T cell therapy in adults with R/R ALL (Park et al., NEJM, 2018). Methods: We performed a retrospective review of adult patients with R/R ALL treated with 19-28z CAR T therapy at MSKCC. Bridging therapy was defined as any therapy given from trial enrollment to cell infusion and classified as either high intensity (remission-inducing or myelosuppressive regimens, eg hyper-CVAD or high-dose cytarabine based regimens) or low intensity (maintenance and/or less myelosuppressive regimens, eg POMP, Blinatumomab, TKI). Results: Of 53 patients who received CAR T cell infusion, 19 were bridged with a high intensity regimen and 34 with a low intensity regimen. There was no difference in number of prior therapies, pre-bridging chemotherapy disease burden, and prior transplant status between groups. High intensity therapy was associated with a higher rate of Gr3-4 infectious complications during the bridging period (78% vs 32%, p &lt; 0.002 by Fisher’s Exact) but not with response to bridging or CAR T cell therapy, relapse free survival, post-CAR Gr3-4 cytokine release syndrome (CRS) or neurotoxicity (NT). Patients in both groups who converted from morphologic to molecular disease during bridging (n=9) had a decreased rate of eventual severe CRS (0% vs 41%, p=0.01) or NT (0% vs 55%, p &lt;0.01) compared to patients with persistent morphologic disease. In all patients enrolled on trial (n=83), use of high compared to low intensity bridging was not associated with higher rates of successful CAR T cell infusion (63% vs 79%, p&gt;0.05) or a combined endpoint of CAR T cell infusion or alternative therapy including transplant (80% vs 86%, p&gt; 0.05). Conclusions: High intensity bridging therapy is associated with a high risk of infectious complications without a clear benefit in outcome in R/R ALL receiving CD19 CAR T cells. Selection of bridging regimen therefore requires consideration of previous treatments and patient status to maximize the efficacy and safety. Clinical trial information: NCT01044069.

Calibrated CAR Activation Potential Directs Alternative T Cell Fates and Therapeutic Potency

Immunotherapy with second-generation chimeric antigen receptor (CAR) T cells has achieved great clinical success against hematological malignancies. CD19-specific CARs incorporating CD28 and CD3z signaling domains have demonstrated remarkable potency resulting in the frequent induction of complete remissions and were recently approved by the US FDA for use in some refractory B cell malignancies. We previously demonstrated that CD28-based CARs program strong effector functions, but impart a relatively limited T cell lifespan. Increasing functional T cell persistence is therefore likely to further enhance the therapeutic success of 1928z CAR T cells.We hypothesized that excessive signal strength arising from redundancy of combined CD3z and CD28 signals might foster terminal T cell differentiation and exhaustion. We therefore proceeded to titrate the activation potential of CD28-based CARs and assess the impact thereof on the function, longevity and therapeutic potency of CAR T cells.We analyzed the contribution of individual immunoreceptor tyrosine-based activation motifs (ITAMs) to the phenotype and function of 1928z CAR T cells. ITAM-mutated CAR T cells demonstrated similar expression levels in retrovirally transduced primary T cells and directed comparable short-term cytotoxicity and proliferation capacity in vitro. However, remarkable differences in their therapeutic potency emerged when T cells expressing different mutant CARs were tested in the pre-B acute lymphoblastic leukemia NALM6 mouse model. The CAR “stress test” model revealed that a CAR containing a single functional ITAM - depending on its position - outperformed wild-type 1928z CARs, achieving rapid and durable tumor eradication even at low T cell doses, by delaying T cell differentiation and exhaustion. CAR T cells retrieved from the bone marrow of treated mice demonstrated that inactivation of two ITAM domains augmented CAR persistence at the tumor sites with a higher percentage of central memory cells and a decreased proportion of terminally differentiated effector cells. Deletion mutants further revealed the importance of ITAM location within second-generation CAR T cells.These findings were rigorously tested by directing the mutant CAR cDNAs to the T-cell receptor α constant (TRAC) locus using CRISPR/Cas9 technology, thereby ruling out potentially confounding effects arising from different CAR expression levels. TRAC-1928z mutants demonstrated superior antitumor efficacy compared to conventional TRAC-1928z CARs and prevented terminal T cell differentiation and exhaustion.Genome-wide transcriptional profiles of TRAC-edited naïve peripheral blood T cells further demonstrated that CARs encoding different ITAMs direct T cells to different fates. While TRAC-1928z CARs demonstrated similarity to transcriptional profiles of effector cells, reducing the number of ITAMs to one ITAM preserved a less-differentiated T cell state and promoted greater T cell persistence. We identified one 1928z mutant CAR, which improved therapeutic potency and induced a transcriptional profile similar to that of stem cell memory T cells (TSCM). Another 1928z mutant CAR with further reduction of the activation potential resulted in a naïve-like phenotype with great proliferation potential and persistence, but greatly diminished anti-tumor efficacy.In conclusion, we demonstrate that the number and position of ITAMs in 1928z CAR T cells influence functional, phenotypic and transcriptional programs resulting in profound effects on therapeutic potency. Balancing T cell differentiation and acquisition of effector functions is essential to optimize therapeutic potency of CAR T cells and can be intrinsically regulated by defined mutations in the CD3z chain of 1928z CAR T cells.Improved therapeutic potency of CAR T cells can thus be achieved by calibrating activation strength, thus retaining memory functions and preventing exhaustion, without compromising effector functions. Importantly, we were able to identify a novel CAR design which programs a favorable balance of effector and memory signatures, inducing increased persistence of highly functional CARs with the replicative capacity of long-lived memory cells and potent effector functions. Clinical studies evaluating the new CAR design are in preparation. DisclosuresSadelain:Juno Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Fate Therapeutics Inc.: Research Funding.

A Phase I First-in-Human Clinical Trial of CD19-Targeted 19-28z/4-1BBL “Armored” CAR T Cells in Patients with Relapsed or Refractory NHL and CLL Including Richter's Transformation

A Phase I First-in-Human Clinical Trial of CD19-Targeted 19-28z/4-1BBL “Armored” CAR T Cells in Patients with Relapsed or Refractory NHL and CLL Including Richter's Transformation

Long-Term Follow-up of CD19 CAR Therapy in Acute Lymphoblastic Leukemia

BackgroundCD19-specific chimeric antigen receptor (CAR) T cells induce high rates of initial response among patients with relapsed B-cell acute lymphoblastic leukemia (ALL) and long-term remissions in a subgroup of patients.MethodsWe conducted a phase 1 trial involving adults with relapsed B-cell ALL who received an infusion of autologous T cells expressing the 19-28z CAR at the Memorial Sloan Kettering Cancer Center (MSKCC). Safety and long-term outcomes were assessed, as were their associations with demographic, clinical, and disease characteristics.ResultsA total of 53 adults received 19-28z CAR T cells that were manufactured at MSKCC. After infusion, severe cytokine release syndrome occurred in 14 of 53 patients (26%; 95% confidence interval [CI], 15 to 40); 1 patient died. Complete remission was observed in 83% of the patients. At a median follow-up of 29 months (range, 1 to 65), the median event-free survival was 6.1 months (95% CI, 5.0 to 11.5), and the median overall survival was 12.9 months (95% CI, 8.7 to 23.4). Patients with a low disease burden (<5% bone marrow blasts) before treatment had markedly enhanced remission duration and survival, with a median event-free survival of 10.6 months (95% CI, 5.9 to not reached) and a median overall survival of 20.1 months (95% CI, 8.7 to not reached). Patients with a higher burden of disease (≥5% bone marrow blasts or extramedullary disease) had a greater incidence of the cytokine release syndrome and neurotoxic events and shorter long-term survival than did patients with a low disease burden.ConclusionsIn the entire cohort, the median overall survival was 12.9 months. Among patients with a low disease burden, the median overall survival was 20.1 months and was accompanied by a markedly lower incidence of the cytokine release syndrome and neurotoxic events after 19-28z CAR T-cell infusion than was observed among patients with a higher disease burden. (Funded by the Commonwealth Foundation for Cancer Research and others; ClinicalTrials.gov number, NCT01044069.)

Impact of disease burden on long-term outcome of 19-28z CAR modified T cells in adult patients with relapsed B-ALL.

7003Background: We have previously reported high anti-tumor activity of CD19-targeted 19-28z chimeric antigen receptor (CAR) modified T cells in adult patients (pts) with relapsed or refractory (R/...

Abstract IA07: Chimeric antigen receptor T cells for cancer immunotherapy

Abstract Background: T cells can be genetically modified to target tumor antigens through the expression of a chimeric antigen receptor (CAR). CAR structure consists of two fundamental domains – the antigen binding portion (most commonly single chain variable fragment (scFv) derived from a monoclonal antibody) joined to one or more intracellular T cell signaling domains. To be effective CAR T cells must expand, persist, exhibit enduring anti-tumor cytotoxicity, withstand and/or counteract an immunosuppressive tumor microenvironment, and overcome targeted tumor antigen escape following infusion. T cells targeting the CD19 antigen is a novel therapeutic approach for patients with hematologic malignancies. To this end, we have previously demonstrated that CAR T cells have a significant clinical benefit in adult patients with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We now extend this novel treatment approach by testing of our CD19-specific CAR in a multicenter trial for children and young adults with relapsed CD19+ B-ALL. Patients and Methods: Pediatric and young-adult patients with very high risk (VHR) or R/R CD19+ B-ALL were eligible for enrollment and leukapheresis. Patients with R/R B-ALL were eligible for infusion if they demonstrated residual disease following salvage chemotherapy. Once eligibility was determined isolation and transduction of T cells was performed using a retroviral vector encoding a CD19-specific CAR comprised of a CD19-specific scFv and the CD28 and CD3ζ signaling domains (termed 19-28z). All patients received conditioning chemotherapy followed 2 days later by 1x106 3x106 19-28z 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. Post-treatment response was assessed at day 14-28 bone marrow aspirate including multiparameter flow cytometry for minimal residual disease (MRD). Results: To date, 28 patients with have been enrolled on protocol with a median age of 11.5 years (range 9 months to 20 years) at time of T cell collection. We have treated 11 patients with 19-28z CAR T cells with a median age 14.9 years (range 3-22 years). Patients received a dose of 1-3 x 10^6 CAR T cells/kg and complete response (complete remission or complete remission with incomplete count recovery) occurred in 7/11 (64%) patients. Significantly, correlations with response included lower disease burden (as assessed by bone marrow cellularity; p&amp;lt;0.004) and fold expansion following CD3/28 bead activation during the generation of CAR T cells (p&amp;lt;0.03). Specifically, BM cellularity ≤50% and fold expansion (average &amp;gt;135 vs &amp;lt;40 fold expansion) was seen in responders compared to non-responders. Pre-collection peripheral blood absolute lymphocyte count, lymphocyte proliferative response (phytohemagglutinin proliferation assay), and CD3 absolute count did not correlate with response in this small sample size. Development of fever and cytokine release syndrome (CRS) occurred in responders including grade I-II (n=3) and grade III-IV (n=4). Systemic immunosuppressants (corticosteroids or anti-IL6 receptor antibody tocilizumab) abrogated clinical symptoms of CRS. Elevated serum cytokines (notably IFN-γ and IL-6) was noted in patients with CRS. Monitoring of bone marrow demonstrated peak 19-28z CAR T cell detection within 1-2 weeks following infusion with gradual contracture over 1-2 months. Conclusions: These early results demonstrate the feasibility and significant clinical impact of CAR T cells in patients with R/R B-ALL. In an effort to more rapidly generate statistically relevant data, demonstrate the exportability of this technology between academic institutions, and offer this therapeutic option to a broader number of pediatric patients with chemo-refractory B-ALL we have expanded this trial to include a collaborating institution. The objective of our trial is not to provide an intent-to-treat cohort, but rather demonstrate the tolerability of this technology in patients with relapsed B-ALL. Furthermore, patients meeting disease eligibility were not pre-screened for lymphocyte function prior to collection and/or treatment. Subsequent cohorts of patients will receive 19-28z CAR T cells and will be evaluated for toxicity, persistence of CAR T cells, and for anti-leukemic efficacy. Citation Format: Kevin J. Curran, Lewis B. Silverman, Rachel Kobos, Nancy A. Kernan, Steven P. Margossian, Jae H. Park, Craig S. Sauter, Victoria Szenes, Xiuyan Wang, Richard J. O'Reilly, Michel Sadelain, Isabelle Riviere, Reiner J. Brentjens. Chimeric antigen receptor T cells for cancer immunotherapy. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Pediatric Cancer Research: From Mechanisms and Models to Treatment and Survivorship; 2015 Nov 9-12; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(5 Suppl):Abstract nr IA07.

Implications of Minimal Residual Disease Negative Complete Remission (MRD-CR) and Allogeneic Stem Cell Transplant on Safety and Clinical Outcome of CD19-Targeted 19-28z CAR Modified T Cells in Adult Patients with Relapsed, Refractory B-Cell ALL

Background: We have previously reported high anti-tumor activity of autologous T cells genetically modified to express 19-28z chimeric antigen receptor (CAR) targeting CD19 in adult patients with relapsed or refractory (R/R) ALL (Park et al. ASH 2014). Herein, we further report the long-term outcome of a larger cohort from our phase 1 clinical trial in adults with R/R ALL (NCT01044069) with a focused analysis on the role of post-treatment minimal residual disease (MRD) negativity as a predictive marker of survival as well as the effect of allogeneic hematopoietic stem cell transplant (allo-HSCT) prior to or after CAR T cell infusion on safety and clinical outcome. Patients and Methods: Adult patients with R/R B-cell ALL (B-ALL) were enrolled. Eligible patients underwent leukapheresis, and T cells were transduced with a retroviral vector encoding a CAR comprising a CD19-specific scFv and CD28 and CD3ζ signaling domains (19-28z). All patients received lymphodepleting chemotherapy followed 2 days later by 1x106 - 3x106 19-28z 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. Post-treatment MRD was assessed at day 14-28 by multiparameter flow cytometry in bone marrow (BM) samples. Results: 44 patients have been treated to date. The median age was 45 years (range, 22-74). 14 patients (32%) had Philadelphia chromosome positive (Ph+) ALL (T315I mutation in 5 patients), 17 patients (39%) had prior allo-HSCT, and 24 patients (55%) had ≥ 3 prior lines of ALL therapy. Of the 44 patients, 43 patients were evaluable for response. At the time of 19-28z CAR T cell infusion, 22 of the 43 patients (51%) had morphologic disease (≥5% blasts in BM or measurable extramedullary disease) and the remaining 21 patients had minimal disease (&lt;5% blasts in BM). 36 patients (84%) were in complete remission (CR) after 19-28z CAR T-cell infusion. MRD analysis was performed in 35 of 36 CR patients, and 29 of these 35 patients (83%) achieved an MRD-negative CR (MRD-CR). As of July 13, 2015, the median follow-up was 4.2 months (range 1-45), with 16 patients having at least 6 months of follow-up. Responses appear durable with 7 patients remaining disease-free beyond 1 year up to 45 months. A median overall survival (OS) of all patients and patients who achieved MRD-CR is 8.5 months and 10.8 months, respectively. Post-treatment MRD status emerged as a strong predictive marker of OS: OS at 6 months was 76% (95% CI: 51-89) in the MRD-CR cohort vs. 14% (95% CI: 8-45) in the MRD+CR cohort. In contrast, allo-HSCT after achieving CR with CAR T cell infusion did not affect the survival rate. Of the 36 patients in CR following the T cell infusion, 12 patients underwent allo-HSCT. OS at 6 months was 70% (95% CI: 33-89) in patients who underwent post-CAR allo-HSCT vs. 64% (95% CI: 36-82) in patients who did not get allo-HSCT after CAR T cells. Comparing baseline disease characteristics of patients who had prior allo-HSCT before the CAR T cell treatment vs. no prior allo-HSCT, patients who had prior allo-HSCT (n=17) were similar in age (median age 45 vs. 46), but had higher disease burden (65% with morphologic disease vs. 44%), were more heavily pretreated (59% of patients with ≥4 lines of therapy vs. 15%), and included more high-risk disease (41% with Ph+ ALL vs. 26%). However, there was no statistically significant difference in CR rates (75%, CI: 48-93 vs. 89%, CI: 71-98), incidences of severe cytokine release syndrome (24% vs. 22%), and OS at 6 months (57% vs. 60%) between these two cohorts. Fewer patients who had prior allo-HSCT underwent another allo-HSCT following CAR T cell infusion: 2 patients vs. 10 patients with no prior all-HSCT. Although no obvious case of graft-versus-host disease (GvHD) was noted, one patient experienced a grade 3 gastrointestinal toxicity that may have been related to GvHD. Conclusions: These data confirm the potent anti-tumor efficacy of 19-28z CAR T cells (JCAR015) in adult patients with R/R ALL. MRD negativity following the 19-28z CAR T cell treatment is highly predictive of survival, and allo-HSCT post-CAR T cell infusion had no significant impact on survival. Furthermore, 19-28z CAR T cells appear to be safe in patients who had prior allo-HSCT, and may represent an attractive alternative option to second allo-HSCT. These findings are being confirmed in an ongoing multi-center, pivotal phase 2 trial evaluating JCAR015 in adult patients with R/R ALL. Disclosures Park: Amgen: Consultancy; Genentech: Research Funding; Juno Therapeutics: Other: Advisory Board, Research Funding. Riviere:Juno Therapeutics: Other: Co-founder, stockholder and consultant. Curran:Juno Therapeutics: Consultancy. Sadelain:Juno Therapeutics: Consultancy, Equity Ownership, Other: Co-Founder, stockholder, Patents &amp; Royalties: Licensed patents on CARs. Brentjens:Juno Therapeutics: Other: Co-founder, stockholder and consultant.

Multi-Center Clinical Trial of CAR T Cells in Pediatric/Young Adult Patients with Relapsed B-Cell ALL

T cells can be genetically modified to target tumor antigens through the expression of a chimeric antigen receptor (CAR). CAR T cells targeting the CD19 antigen is a novel therapeutic approach for patients with relapsed B cell acute lymphoblastic leukemia (B-ALL). We have previously demonstrated that CAR T cells have a significant clinical benefit in adult patients with relapsed B-ALL. The primary objective of this study (NCT01860937) is to extend the use and test the safety of CD19 specific CAR T cells in a multicenter trial for children and young adults with relapsed CD19+ B-ALL. To date, 24 patients with very high risk (VHR) or relapsed B-ALL have been enrolled on protocol with a median age of 12 years (range 2-20 years) at time of T cell collection. We have treated 9 patients with relapsed B-ALL with a median age 15 years (range 3-22 years) using patient derived T cells expressing a CD19 specific CAR (19-28z). Patients received a dose of 1-3 x 10^6 CAR T cells/kg and complete response (complete remission or complete remission with incomplete count recovery) occurred in 5/9 (55%) patients. Significantly, correlations with response included lower disease burden (as assessed by bone marrow cellularity; p<0.02) and fold expansion following CD3/28 bead activation during the generation of CAR T cells (p<0.02). Specifically, BM cellularity ≤50% and fold expansion (average >150 vs <40 fold expansion) was seen in responders compared to non-responders. Pre-collection peripheral blood absolute lymphocyte count, lymphocyte proliferative response (phytohemagglutinin proliferation assay), and CD3 absolute count did not correlate with response in this small sample size. Development of fever and cytokine release syndrome (CRS) occurred in responders including grade I-II (n=2) and grade III-IV (n=3). Systemic immunosuppressants (corticosteroids or anti-IL6 receptor antibody tocilizumab) abrogated clinical symptoms of CRS. Elevated serum cytokines of IFN-g (>20 fold), fractalkine (>20 fold), Flt-3L (>55 fold), IL-5 (>15 fold), IL-6 (>100 fold), and IL-10 (>15 fold) were demonstrated in patients with CRS. Monitoring of bone marrow demonstrated peak 19-28z CAR T cell detection within 1-2 weeks following infusion with gradual contracture over 1-2 months. These early results demonstrate the feasibility and significant clinical impact of this approach in patients with relapsed B-ALL. In an effort to more rapidly generate statistically relevant data, demonstrate the "exportability" of this technology between academic institutions, and offer this therapeutic option to a broader number of pediatric patients with chemo-refractory B-ALL we have expanded this trial to include a collaborating institution. The objective of our trial is not to provide an intent-to-treat cohort, but rather demonstrate the tolerability of this technology in patients with relapsed B-ALL. Furthermore, patients meeting disease eligibility were not pre-screened for lymphocyte function prior to collection and/or treatment. Subsequent cohorts of patients will receive 19-28z CAR T cells and will be evaluated for toxicity, persistence of CAR T cells, and for anti-leukemic efficacy. DisclosuresCurran:Juno Therapeutics: Consultancy. Off Label Use: CAR T cells for B-ALL. Riviere:Juno Therapeutics: Other: Co-founder, stockholder and consultant. Prockop:Atara Biotherapeutics: Other: I have no financial disclosures, but Atara Biotherapeutics has exercised a licensing agreement with Memorial Sloan Kettering Cancer Center and MSKCC and some investigators at MSKCC have a financial interest in Atara.. Park:Actinium Pharmaceuticals, Inc.: Research Funding; Juno Therapeutics: Consultancy. O'Reilly:Atara Biotherapeutics: Research Funding. Sadelain:Juno Therapeutics: Other: Co-founder, stockholder and consultant. Brentjens:Juno Therapeutics: Other: Co-founder, stockholder and consultant.

Phase I trial of 19-28z chimeric antigen receptor modified T cells (19-28z CAR-T) post-high dose therapy and autologous stem cell transplant (HDT-ASCT) for relapsed and refractory (rel/ref) aggressive B-cell non-Hodgkin lymphoma (B-NHL).

8515 Background: HDT-ASCT is the standard of care for patients with rel/ref diffuse large B-cell lymphoma (DLBCL). Herein, we report safety data on the first 8 patients of our phase I clinical tria...

475. Phase I Clinical Trial of Autologous CD19-Targeted 19-28z CAR T Cells in Adult Patients With Relapsed or Refractory B-ALL

Adult patients with relapsed or refractory (R/R) acute lymphoblastic leukemia (ALL) have a dismal prognosis with a median overall survival (OS) < 6 months. Salvage chemotherapy is ineffective and often induces only a transient remission. We previously reported high anti-tumor activity of autologous T cells genetically modified to express 19-28z chimeric antigen receptor (CAR) targeting CD19 antigen in adult patients with ALL (Davila M et al. Sci Transl Med 2014). Herein, we report updated results and long-term outcome from our phase I clinical trial of 19-28z CAR T cells in adult patients with R/R ALL (NCT01044069). Adult patients with R/R B-ALL were enrolled, and underwent leukapheresis. T cells were transduced with a gamma-retroviral vector 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 1-3 x106 CAR T cells/kg. Bone marrow (BM) biopsy was performed immediately prior to T cell infusion for disease status assessment. 28 patients (pts) have been treated to date. The median age was 55 years (range, 23-74). 9 pts (32%) had Ph+ B-ALL (T315I mutation in 3 pts), 8 pts (29%) had prior allogeneic stem cell transplant (allo-SCT), and 22 pts (78%) had either primary refractory disease or CR1 duration of <12 months. Of the 28 pts, 27 pts were evaluable for response. At the time of 19-28z CAR T cell infusion, 14 of 27 evaluable pts had morphologic disease (>5% blasts in BM) and 13 pts had minimal residual disease (MRD). 24 of 27 pts (89%) were in complete remission (CR) following the 19-28z CAR T cell infusion; 11 of these pts had morphologic disease at the time of T cell infusion, and 13 pts had MRD. 21 of 24 CR (88%) was MRD negative. A median time to CR was 22.5 days (range, 9-33). 10 pts successfully underwent allo-HSCT following the 19-28z CAR T cell therapy. The median follow-up is 6 months (range, 1-38 months) with 15 pts having at least 6 months of follow-up. Responses appear durable with 12 pts remaining disease-free, including 7 pts without subsequent allo-SCT. Median OS of all pts is 8.5 months. While none of the 13 pts with MRD at the time of T cell infusion developed significant cytokine release syndrome (CRS), 5 of 15 pts with morphologic disease developed severe CRS that required either vasopressors or mechanical ventilation for hypoxia, successfully managed with corticosteroid and/or IL-6R inhibitor. Treatment with 19-28z CAR T cells can induce a high CR rate of 89% in these heavily pretreated adult pts with R/R ALL regardless of the disease risk characteristics including Ph+ status, age, pre-T cell disease burden, prior allo-SCT, and CR1 duration. While CRS can develop following T cell infusion, the risk of CRS predictably correlates with the disease burden and can successfully be managed with corticosteroid and/or IL-6R inhibitor. These findings support the use of 19-28z CAR T cells in adult pts with R/R ALL and warrant a further investigation in a larger phase 2 trial.

A Systemic Xenograft Model of Waldenström’s Macroglobulinemia Demonstrates the Potent Anti-Tumor Effect of Second Generation CD19 Directed Chimeric Antigen Receptor Modified T Cells in This Disease

Chimeric antigen receptor (CAR) modified T-cell therapy consists of ex-vivo genetic manipulation of autologous lymphocytes in order to establish robust T-cell mediated anti-tumor immunity. Our group was the first to design and evaluate a CAR targeted toward the B cell antigen CD19 in mice. Currently we utilize a second generation CAR comprised of a single-chain variable fragment (scFv) derived from an antibody against CD19 fused to the CD3 ζ chain and the CD28 intracellular signaling domain (19-28z) to provide the necessary signal 1 and signal 2 for enhanced T-cell activation and persistence. We have gone on to test the safety and efficacy of 19-28z CAR T-cells in patients with chronic lymphocytic leukemia (CLL) and acute lymphoblastic leukemia (ALL). We observed rapid complete molecular remissions in the first 14/16 patients treated with relapsed/refractory ALL. We hypothesize that contributing to the enhanced efficacy seen in ALL, when compared to solid tumors or extra-medullary CLL, is the fact that ALL is a bone marrow predominant disease, which may provide a microenvironment more amenable to T-cell therapy.Waldenström’s Macroglobulinemia (WM) is an ideal disease to test 19-28z CAR-modified T-cell therapy, as it is often bone marrow predominant, and WM cells from patient samples typically uniformly express high levels of CD19. Furthermore, despite recent progress made with novel BCR-directed therapy, complete eradication of the WM clone from the bone marrow niche remains elusive, therefore providing an ideal clinical scenario for treatment consolidation via alternative cytotoxic methods such as cellular immunotherapy.Using the human WM cell line, BCWM.1, we evaluated the in vitro efficacy of 19-28z CAR-modified T-cells when compared to mock transduced T cells or T cells transduced with an irrelevant second generation CAR directed towards the ovarian antigen MUC16. In a 4 hour co-culture assay, we observed significant cytotoxicity, even at low effector:target ratios (52% lysis at 1:1; 92% lysis at 10:1; p<0.01). This corresponded to increased secretion of INFγ and IL-2, markers of T-cell activation (p<0.01).We then conducted in vivo studies using sublethally irradiated SCID/beige mice to generate a systemic model of WM via tail vein injection of 1x106 luciferase transduced BCWM.1 cells. This model is characterized by tumor growth in the bone marrow followed by rapid spread to the liver, lungs, kidney, and CNS. Mice were monitored by weekly bioluminescent imaging (BLI) and ultimately were sacrificed when they developed hind leg paralysis. 19-28z CAR modified T-cells administered at day 7, after tumor establishment, when compared to non-treated and irrelevant CAR-modified T cell controls, delayed the progression of disease and doubled the median survival time of the mice after treatment (p=0.001).Taken together, the pre-clinical efficacy demonstrated in this abstract and the clinical features of WM, listed above, provide the rational for testing 19-28z CAR modified T cells clinically for WM. We have now opened a clinical trial for patients with relapsed or refractory WM, in which chemotherapy preconditioning is followed by a single dose of 19-28z CAR modified autologous T-cells (NCT00466531). DisclosuresBrentjens:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other.

Chimeric Antigen Receptor (CAR) T Cells Targeting the CD19 Antigen for the Treatment of Pediatric Relapsed B Cell ALL

T cells can be genetically modified to target tumor antigens through the expression of a chimeric antigen receptor (CAR). CAR T cells targeting the CD19 antigen is a novel therapeutic approach for patients with relapsed B cell acute lymphoblastic leukemia (B-ALL). We have previously demonstrated that CAR T cells have a significant clinical benefit in adult patients with relapsed B-ALL. The primary objective of this study (NCT01860937) is to extend the use and test the safety of CD19 specific CAR T cells in children with relapsed CD19+ B-ALL. To date, 11 pediatric patients with very high risk (VHR) or relapsed B-ALL have been enrolled on protocol with a median age of 13 years (range 2-23 years) at time of T cell collection. We have treated 4 pediatric patients with relapsed B-ALL (ages 13, 14, 19, and 22 years) using patient derived T cells expressing a CD19 specific CAR (19-28z). Complete response (complete remission or complete remission with incomplete count recovery) occurred in 2/4 (50%) patients. Severe cytokine release syndrome (sCRS) defined by fever for ≥3 consecutive days, elevated serum cytokine levels, and one clinical sign of toxicity (hypotension, hypoxia, neurologic disorder including altered mental status, obtundation, and/or seizure) occurred in both patients who responded to CAR T cells. Morphologic disease (≥5% bone marrow blasts) at time of treatment was present in three patients including both patients with sCRS. Systemic immunosuppressants (corticosteroids or anti-IL6 receptor antibody tocilizumab) abrogated clinical symptoms of sCRS. Elevated serum cytokines of IFN-g (>20 fold), fractalkine (>20 fold), Flt-3L (>55 fold), IL-5 (>15 fold), IL-6 (>100 fold), and IL-10 (>15 fold) were demonstrated in patients with sCRS. Monitoring of bone marrow demonstrated peak 19-28z CAR T-cell detection within 1-2 weeks following infusion with gradual contracture over 2-3 months. These early results demonstrate the feasibility and significant clinical impact of this approach in patients with relapsed B-ALL. To more rapidly generate statistically relevant data, demonstrate the “exportability” of this technology between academic institutions, and offer this therapeutic option to a broader number of pediatric patients with chemo-refractory B-ALL our trial will expand into a phase I multicenter clinical trial with a collaborating institution. Subsequent cohorts of patients will receive 19-28z CAR T cells and will be evaluated for toxicity, persistence of CAR T cells, and for anti-leukemic efficacy. DisclosuresOff Label Use: CAR T cells for relapsed B-ALL. Riviere:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other. Boulad:Genzyme Sanofi: Trials partially funded by Genzyme Sanofi Other. Sadelain:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other. Brentjens:Juno Therapeutics: Consultancy, Scientific co-founder and Stock holder Other.

CD19-Targeted 19-28z CAR Modified Autologous T Cells Induce High Rates of Complete Remission and Durable Responses in Adult Patients with Relapsed, Refractory B-Cell ALL

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 (<60 vs. ≥60), prior allo-HSCT, number of prior therapies, or pre-treatment blast percentage.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. DisclosuresPark: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.

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.

Cancer CARtography: charting out a new approach to cancer immunotherapy.

Evaluation of: Davila ML, Riviere I, Wang X et al. Efficacy and toxicity management of 19-28z CAR T cell therapy in B cell acute lymphoblastic leukemia. Sci. Transl. Med. 6(224), 224ra25 (2014). Recently, chimeric antigen receptor (CAR) T-cell immunotherapy has entered clinical trials in patients with relapsed or refractory B-cell acute lymphoblastic leukemia. 19-28z CAR T cells express a fusion protein comprised of an anti-CD19 mAb fused with CD28 costimulatory and CD3-zeta-chain signaling domains. The current paper demonstrates that administration of 19-28z CAR T cells in patients with relapsed or refractory B-ALL in a Phase I clinical trial has led to 88% of patients undergoing complete remission. Despite the benefits, CAR T-cell therapy is associated with cytokine release syndrome toxicities. The authors demonstrated criteria to diagnose severe cytokine release syndrome (sCRS) and treated sCRS with either high-dose steroids or with tocilizumab, an IL-6 receptor-specific mAb. Although both alleviated sCRS, steroid treatment negated the beneficial effects of CAR T-cell therapy, whereas tocilizumab did not. Taken together, CAR T-cell immunotherapy can be used as a safe and effective approach against tumors with known tumor-associated antigens.