ALBERT

Description: Introduction CTL019 is a novel, investigational, chimeric antigen receptor (CAR) immunotherapy whereby autologous T cells are genetically modified with a chimeric antigen receptor to target CD19 on the surface of malignant as well as healthy B cells. The cellular kinetics of CTL019 have been evaluated in several trials for patients with relapsed/refractory CD19+ leukemias, including pediatric acute lymphoblastic leukemia (pALL), adult ALL (aALL), and chronic lymphocytic leukemia (CLL) (Maude 2014, Porter 2015). Methods The cellular kinetic profile of CTL019 was determined in peripheral blood (PB) and bone marrow (BM) through serial measurements using flow cytometry and quantitative real-time polymerase-chain-reaction (qPCR) assay in 3 studies comprised of (i) 55 pALL patients (NCT01626495), (ii) 28 adult CLL patients from a dose selection study (NCT01747486), and (iii) 14 CLL and 6 adult ALL patients (NCT01029366). The flow cytometry assay used a CAR19-specific anti-idiotype antibody to enumerate CTL019 T cells as a % of CD3+ T cell (Porter 2015). Cellular kinetic parameters included: maximal extent of expansion as measured by peak copies of CTL019 DNA and peak % by flow cytometry (Cmax), area under the curve at day 28 (AUC0-28d) describing expansion and persistence in the first month, and time to reach Cmax (Tmax). Parameters were derived by non-compartmental methods. Where estimable, persistence was described by the half-life (T1/2) based on the slope of the terminal phase. Results Following infusion, CTL019, expansion and persistence was evident in the patients who responded to CTL019 as measured by both PK assays across all 3 studies. Table 1 summarizes (arithmetic mean (SD)) the CTL019 kinetic parameters. With complete remission (CR/CRi), CTL019 cells undergo rapid in vivo expansion beyond the original CTL019 dose with maximal expansion at a mean of 11 days in pALL and aALL and approximately 14-18 days in adult CLL as determined by qPCR and flow cytometry (Table 1). In CR/CRi patients the transgene level-profiles in PB reveal a kinetic profile with an initial rapid expansion followed by a slower decay function with some fluctuations of transgene over time resulting in higher AUC0-28d and Cmax, while non-responder (NR) patients tend to have a lower expansion and faster decay (shorter T1/2)of CAR positive T-cells resulting in lower AUC0-28d and Cmax by, leaving the mechanism to be further explored. In pALL, significantly higher AUC0-28d and Cmax were observed in CR/CRi patients compared to NR patients by flow cytometry; however, a wide range of mean AUC0-28d and Cmax was observed in NR patients (n=3) resulting from significant expansion in one NR patient as determined by qPCR. In CLL, the exposure metrics AUC0-28d and Cmax were approximately 12 times higher in CR/CRi patients compared with PRi/NR/PD in NCT01747486; a similar trend was observed in NCT01029366. Similar findings were captured by the flow cytometry based measurements as summarized in Table 1. In pALL and CLL, CR/CRi patients tend to maintain higher levels of CTL019 transgene over longer periods of time (〉6 months) compared to NR patients as demonstrated by the longer T1/2 value. Cellular kinetic parameters were not summarized by response category for aALL due to the small sample size (n=5 CR/CRi; n=1 NR). CTL019 transgene levels ranged from below the limit of quantification (BLQ) to 178,000 copies/ug in aALL patients with CR/CRi and BLQ to 21,900 copies/ug in the NR. CTL019 positive cells were also shown to traffic to BM at 1 month in responders (CR/CRi), irrespective of the disease. Conclusions Overall, significantly higher levels of in vivo proliferation and persistence were observed in patients who successfully responded to CTL019 (i.e. CR/CRi/PR) compared to NRs in both CLL and (adult and pediatric) ALL patients, as captured by both analytical measures, indicating that the kinetics of CTL019 T cells and that proliferation and persistence of CTL019 reasonably predicts response to therapy. These are the first three studies to demonstrate that cellular kinetics may predict responses to CAR based cellular therapy. These results imply that measures to increase proliferation and persistence of CAR T cells may enhance responses in resistant patients. Figure. CTL019 concentration-time profiles for %CD3+/CTL019+ measured by flow cytometry and cellular kinetic parameters for qPCR and flow cytometry for p-ALL and adult CLL Figure. CTL019 concentration-time profiles for %CD3+/CTL019+ measured by flow cytometry and cellular kinetic parameters for qPCR and flow cytometry for p-ALL and adult CLL Disclosures Mueller: Novartis Pharmaceuticals: Employment. Chakraborty:Novartis Pharmaceuticals: Employment, Equity Ownership. Wood:Novartis Pharmaceuticals: Employment, Other: Stock. Awasthi:Novartis Pharmaceuticals: Employment. Quintas-Cardama:Novartis Pharmaceuticals: Employment, Equity Ownership. Han:Novartis Pharmaceuticals: Employment, Equity Ownership. Maude:Novartis: Consultancy. Grupp:Jazz Pharmaceuticals: Consultancy; Pfizer: Consultancy; Novartis: Consultancy, Research Funding. Porter:Novartis: Patents & Royalties, Research Funding; Genentech: Employment. Frey:Novartis: Research Funding; Amgen: Consultancy. Marcucci:Novartis: Research Funding. Levine:GE Healthcare Bio-Sciences: Consultancy; Novartis: Patents & Royalties, Research Funding. Melenhorst:Novartis: Research Funding. June:Celldex: Consultancy, Equity Ownership; Immune Design: Consultancy, Equity Ownership; Pfizer: Honoraria; Novartis: Honoraria, Patents & Royalties: Immunology, Research Funding; University of Pennsylvania: Patents & Royalties; Tmunity: Equity Ownership, Other: Founder, stockholder ; Johnson & Johnson: Research Funding. Lacey:Novartis: Research Funding.

Description: Introduction: Hepatic veno-occlusive disease (VOD) is a serious complication of hematopoietic stem cell transplantation (HSCT) and, in severe cases, is associated with multi-organ failure and mortality rates exceeding 80% (Coppell et al. Biol Blood Marrow Transplant, 2010, p157-168). In the US there are currently no FDA-approved treatments for severe VOD. Defibrotide, an oligonucleotide with a mechanism of action that encompasses both restoration of the thrombo-fibrinolytic balance and endothelial cell protection, has recently been approved for the treatment of severe VOD following HSCT in the EU. The data presented are based on the primary and secondary endpoint analyses provided to the European Medicines Agency (EMA) that formed the basis of the defibrotide approval in the EU. Methods: A pivotal phase 3 study examined the efficacy and safety of defibrotide 25 mg/kg/day in patients with severe VOD (n=102) compared to historical controls (n=32) (Defibrotide Summary of Product Characteristics. Villa Guardia, Italy: Gentium SpA; 2013). The study’s primary endpoint was complete response (CR) (in terms of improvements in total bilirubin and resolution of multi-organ failure measured by renal and/or pulmonary dysfunction) by 100 days post-HSCT; secondary endpoints included survival 100 days and 180 days post-HSCT. We calculated the number needed to treat (NNT) with defibrotide to achieve one complete response and the NNT to prevent one death 100 days post-HSCT in patients with severe VOD compared to historical controls who did not receive defibrotide in order to evaluate how defibrotide compared to other novel and efficacious agents used for rare conditions in hemato-oncology. NNT is calculated as the reciprocal of the absolute risk reduction (1/ARR), where ARR is equal to the control minus experimental event rates (Laupacis et al, New Engl J Med, 1988, p1728-1733). Results: In the defibrotide trial, complete response by day 100 was achieved in 23.5% of the defibrotide-treated patients and 9.4% of the historical controls (P=0.013), which equated to an NNT of 7 (1/(0.235-0.094)) to achieve one complete response 100 days post-HSCT. Day 100 survival was 38.2% in the defibrotide group and 25.0% in the historical control group (P=0.034) (Defibrotide Summary of Product Characteristics. Villa Guardia, Italy: Gentium SpA; 2013). Therefore, the NNT to prevent one death in this study was 8 (1/(0.382-0.25)). To compare the NNTs in this analysis with those in other studies, a literature search was conducted, identifying a selected number of pediatric oncology clinical trials published within the previous 10 years each of which reported 5-year EFS rates (Sorrell et al, Cancer, 2012, p4806-4814; La et al, Int J Radiat Oncol Biol Phys, 2011, p1151-1157; Chou et al, Cancer, 2009, p5339-5348; Lange et al, Blood, 2008, p1044-1053; MacDonald et al, Cancer, 2005, p2862-2871). NNTs calculated from that review ranged from 5 to 50. Conclusion: The results of this pivotal Phase 3 trial showed improved complete response and survival in defibrotide-treated patients compared to historical controls who did not receive defibrotide for the treatment of severe VOD. The number needed to treat to achieve this benefit proved either comparable or lower than the NNT obtained for other widely-accepted and approved therapeutic medical interventions in hemato-oncology. Support: Jazz Pharmaceuticals Off-Label Use: Defibrotide is an investigational treatment for hepatic veno-occlusive disease in the United States. Disclosures Richardson: Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals Inc.: Research Funding. Off Label Use: Defibrotide is an investigational treatment for veno-occlusive disease in the United States.. Martin:EUSA Pharma - an international division of Jazz Pharmaceuticals: Employment; Jazz Pharmaceuticals: Equity Ownership. Hannah:Jazz Pharmaceuticals: Consultancy. Villa:Jazz Pharmaceuticals: Employment, Equity Ownership.

Description: Background: Severe hepatic veno-occlusive disease (VOD, also referred to as sinusoidal obstruction syndrome) with associated multi-organ failure (MOF) is a life-threatening complication of hematopoietic stem cell transplant (HSCT) and has an associated mortality rate 〉80%. Defibrotide has been shown to have a protective effect on injured endothelium and to restore the thrombo-fibrinolytic balance. In severe VOD, defibrotide has improved complete response (CR) rates and survival at Day +100 post HSCT compared with historical controls, and has also been shown to have a favorable safety profile. In the EU, defibrotide is now approved for the treatment of severe hepatic VOD in HSCT therapy. It is indicated in adults, adolescents, children, and infants 〉1 month of age. In the USA, there are currently no approved therapies for this complication; however, defibrotide has been made available since 2007 through an expanded access protocol directed treatment IND (T-IND). The aim of the T-IND is to gather additional data on safety and efficacy of defibrotide in a broader patient population, including those with severe VOD/MOF post HSCT, non-severe VOD post HSCT, and VOD following chemotherapy in the non-HSCT setting. This is the largest prospective evaluation of defibrotide for the treatment of VOD. Here we provide an update on the safety of defibrotide from this ongoing study. Methods: The original T-IND protocol required patients to have a diagnosis of VOD by Baltimore criteria (total bilirubin ≥2.0 mg/dL with ≥2 of the following: hepatomegaly, ascites, or 5% weight gain) with MOF (either renal and/or pulmonary failure) following HSCT; the study was amended to allow inclusion of patients with non-severe VOD (defined as no MOF) occurring either post-HSCT or post-chemotherapy. Key exclusion criteria include clinically significant bleeding or the need for 〉1 vasopressor. Defibrotide was given as a 2-hour infusion at 6.25 mg/kg IV every 6 hours (25 mg/kg/d) with a recommended minimum treatment duration of 21 days. Results: The current interim safety analysis is based on 612 patients enrolled between December 2007 and December 2013 (including 99 in 2013) for whom safety data is available and who received ≥1 dose of defibrotide. Across the USA, over the course of the study approximately 86 centers were active to enroll patients. Median patient age was 12 years (range 18 to 65 years, and 1.2% aged 〉65 years. Patients were primarily male (55.8%) and predominantly white (65.6%). Overall, 454 patients (74.2%) reported ≥1 treatment emergent adverse events (AEs). Of these, 138 patients (22.5%) had AEs that investigators assessed as related (possibly, probably, or definitely) to study medication. Related AEs in 〉2.0% were pulmonary hemorrhage (4.7%), gastrointestinal hemorrhage (3.6%), epistaxis (3.1%), and hypotension (2.8%). Serious AEs (SAEs) were reported by 368 patients (60.1%). The majority of SAEs were assessed as not related to study treatment; 82 patients (13.4%) had an SAE at least possibly related to study treatment, most commonly pulmonary hemorrhage (3.9%) and gastrointestinal hemorrhage (2.9%). AEs leading to death occurred in 254 patients (41.5%); these AEs were deemed by the investigators to be possibly related to study medication in only 17 patients (2.8%). Previously reported efficacy data at D +100 in 425 patients evaluable for outcome have shown survival of 55% (by Kaplan-Meier estimate) for patients following HSCT, and survival of 62% (by Kaplan-Meier estimate) in 45 patients following chemotherapy (without HSCT), respectively. Conclusions: Defibrotide therapy in patients with VOD was generally well tolerated in this population, with manageable toxicity, and promising results seen in terms of response and survival. Safety results from prior studies, which have also been associated with a low incidence of defibrotide-associated toxicities, have proven very consistent with the favorable tolerability profile seen in this largest experience to date. Enrollment to the T-IND study continues; updated results will be presented at the meeting. Support:Jazz Pharmaceuticals Off-Label Use Defibrotide is an investigational treatment for hepatic veno-occlusive disease in the United States. Disclosures Richardson: Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals Inc.: Research Funding. Off Label Use: Defibrotide is an investigational treatment for veno-occlusive disease in the United States.. Antin:Dana-Farber Cancer Institute: Employment; Tempera: Consultancy; Enlivex: Consultancy. Lehmann:Dana Farber/Boston Children's Hospital: Employment. Bandiera:Gentium S.p.A.: Employment. Hume:Jazz Pharmaceuticals Inc.: Employment. Hannah:Jazz Pharmaceuticals: Consultancy. Nejadnik:Jazz Pharmaceuticals: Employment. Study Group:Gentium S.p.A.: Employment.

Description: Introduction: Anti-CD19 chimeric antigen receptor T cells (CART19) generate unprecedented complete response rates of up to 90% in relapsing/refractory acute lymphoblastic leukemia. Associated with this therapy is a multi-symptom toxicity known as cytokine release syndrome (CRS). Clinically CRS resembles macrophage activation syndrome (MAS), with a pattern of cytokines in serum coupled with other biomarkers (such as ferritin) and physical findings (fever, sudden organomegaly, confusion). Clinical interest has focused on interleukin-6 (IL-6), as blocking this pathway with tocilizumab (an IL-6R antagonist) has relieved the most life-threatening aspects of CRS in patients. Nothing is known, however, about the mechanism behind the triggering of CAR associated CRS/MAS nor the cellular sources of the toxic cytokines. This is a critical lack of knowledge, as each CAR product may result in a different CRS resulting in different clinical outcomes and management strategies. We sought to identify the cellular source of IL-6 and other MAS cytokines specifically during a 41BB CAR mediated CRS, and cross validate with investigations into patient peripheral blood PBMCs during CRS. Results: Using a xenograft model of a primary patient leukemia and CART19 from a patient that experienced Grade 4 CRS, we measured cytokine production in the serum of animals 3 and 7 days post CART19. While we could detect GMCSF, IL-2 and IFNg easily, IL-6 was not detected and the animals did not appear ill during this phase despite disease response. Given the clinical similarities of CRS to MAS, we performed co-culture of CART19 T cells, Nalm-6 leukemia and cells derived in vitro from peripheral blood monocytes (which were autologous to the CAR T cells) including immature dendritic cells (iDC), mature dendritic cells (mDC) and macrophages. Similar to the in vivo results, coculture of CART19 and Nalm-6 produced high levels of GMCSF, IFNg, IL-2 and IL-10 but no detectable IL-6 or IL-8. Only in the presence of the monocyte lineage antigen presenting cells (APCs) did we observe IL-6 and IL-8 release (more than 100 fold increase over controls). Transwell in vitro experiments separating CART19/Nalm-6 from the APCs showed the same pattern, indicating the CART19 mediated killing of target cells induces the IL-6 release from APCs in a contact independent manner. Nanostring RNA analysis of separated cell populations indicated that IL-6 and IL-8 are exclusively produced by APCs, not CART19 or Nalm-6 (Figure 1). Both CD107a degranulation and the total Nanostring RNA profile of CART19 was not different in the presence or absence of APCs, indicating that an MAS-like CRS is likely not part of CART19 efficacy. Finally, we analyzed the peripheral blood mononuclear cells of 18 patients receiving CART19 for pediatric ALL by Nanostring. Patients with Grade 4 CRS and only circulating T cells showed no IL-6 or IL-8 RNA, confirming in vivo that CART19 cells are not the cellular source of IL-6 during CRS. Unsupervised clustering of the Nanostring profiles also revealed four distinct gene signatures: one for patients with only circulating leukemic blasts, two for Grade 2-3 CRS that clustered separately and one for Grade 4 CRS (Figure 2). Conclusions: Here we demonstrate that IL-6 as part of CRS is produced by APCs and not T cells in response to CART19 mediated killing of leukemia, and that CART19 cells do not seem affected by the presence of CRS cytokines either in transcriptional profile or killing potential. This data provides the rationale for blocking this toxic cytokine before symptoms appear without changing CART19 efficacy, in addition to supporting a rapid Nanostring based profile to identify prospectively the patients at risk for Grade 4 CRS. Figure 1. Scatterplot of RNA transcript levels from CAR T cells (blue) in the act of killing leukemia cells versus the transcript levels from APCs separated by transwell insert. There are clear distinctions on the cellular source of key cytokines in CRS, including IFNg, GMCSF and IL2 from CAR T cells and IL6 and IL8 from APCs. Figure 1. Scatterplot of RNA transcript levels from CAR T cells (blue) in the act of killing leukemia cells versus the transcript levels from APCs separated by transwell insert. There are clear distinctions on the cellular source of key cytokines in CRS, including IFNg, GMCSF and IL2 from CAR T cells and IL6 and IL8 from APCs. Figure 2. Unsupervised clustering shows four groups of CRS clusters based on T cell, monocyte and B cell genes. Each column is a patient sample, each row a single gene. Grade 4 is dominated by T cell genes only. Figure 2. Unsupervised clustering shows four groups of CRS clusters based on T cell, monocyte and B cell genes. Each column is a patient sample, each row a single gene. Grade 4 is dominated by T cell genes only. Disclosures Barrett: Novartis: Research Funding. Grupp:Novartis: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy; Pfizer: Consultancy.

Description: Abstract 470 We previously reported lower rates of grade II-IV aGVHD, but no improvement in survival with the addition of sirolimus to tacrolimus/methotrexate GVHD prophylaxis in a randomized phase III Children's Oncology Group/Pediatric Blood and Marrow Transplant Consortium trial, ASCT 0431. We performed further analysis of this cohort to test whether the presence or absence of aGVHD combined with detection of pre- and/or post-HCT minimal residual disease (MRD) would allow definition of high-risk populations amenable to early intervention to prevent relapse. MRD was measured on patient bone marrow samples with multi-channel flow cytometry at a single reference laboratory (detection threshold 0.01%). The trial included children ages 1–21yrs with high-risk CR1 and CR2 ALL receiving related and unrelated donor TBI-based allogeneic HCT. The analysis included 144 eligible patients with an estimated median follow up of 757d (interquartile range 558–1022d). Both the absence of grade II-IV aGVHD at day 100 and positive MRD pre-and/or post-HCT were correlated with relapse. To illustrate the effect of aGVHD on relapse, Table 1 shows the cumulative incidence of TRM, relapse, and EFS at 100 days, 1 yr, and 2 yrs after HCT in patients with or without aGVHD. Table 1. Effect of grade II-IV aGVHD by day 100 on TRM, Relapse, and EFS Time post-HCT # of Pts at Risk TRM Relapse EFS yes aGVHD no aGVHD yes aGVHD no aGVHD yes aGVHD no aGVHD yes aGVHD no aGVHD Day 100 69 44 3.0% 6.6% 0.8% 3.7% 35% 51% 1 year 32 55 4.6% 7.4% 5.0% 24% 31% 28% 2 years 17 19 7.0% 7.4% 6.4% 30% 27% 22% Thirty eight percent of patients developed grade II-IV aGVHD (most (89%) by day +50). Analysis of patients who did or did not experience aGVHD by day 100 showed that patients who developed aGVHD rarely experienced TRM or relapse from that time forward (7.0 and 6.4% with TRM and relapse at 2 yrs post-HCT, respectively). Conversely, patients who did not develop aGVHD had a small risk of early relapse (3.7% at d100) but a steadily increasing rate of relapse starting day 200 post-HCT. Patients who did not develop grade II-IV aGVHD relapsed nearly 5 times more than those with aGVHD (30% vs. 6.4 at 2 yrs), with the result that EFS at 2 years was 19% (17/89) in those with no aGVHD vs. 35% (19/55) in those with aGVHD (p=0.001). It is important to note that the occurrence of aGVHD did not impact the rate of TRM. To assess the effect of the MRD status on relapse, we measured MRD by flow cytometry of BM pre-HCT, within 2 wks of engraftment, and at 3, 6, 9, or 12m after HCT and correlated the presence of MRD in these samples with relapse rates. More than 400 samples were analyzed. For patients positive for pre-HCT MRD, the rate ratio (RR) for relapse was 3.7 (1.6–8.2) with an estimated two-year relapse risk of 27.4% (17.4–43.1) and 70.8% (50.4–99.4) in pre-HCT MRD negative and positive patients, respectively. For patients positive for post-HCT MRD, we constructed a Cox regression model to assess the effect of positive post-HCT MRD in the context of other transplant-related variables. In the post-HCT period, an MRD positive result was associated with a 14-fold increase in relapse rate over an MRD negative result (RR=14.3, 95% CI:6.1–33.6). These findings did not change after controlling for risk group, immunophenotype, donor type and pre-HCT MRD status. Finally, we did an analysis of the combined effect of aGVHD and MRD status. Patients who developed grade II-IV aGVHD had low rates of post-HCT MRD and relapse, and a combined predictive effect of MRD status in patients with aGVHD could not be assessed. However, among patients who did not develop aGVHD, pre- and post-HCT MRD statuses were found to be independent risk factors for relapse (Table 2). Table 2. Effect of Pre- and Post-HCT MRD on Relapse risk of Patients without aGHVD Pre-HCT MRD Post HCT MRD RR for Relaspe (CI) - - 1 (reference) + - 2.5 (1.0-5.8) - + 12.7 (4.2-38.2) + + 31.2 (7.5-129.3) In summary, measurement of flow MRD on BM samples pre- and early post-HCT is feasible and positive results along with absence of grade II-IV aGVHD is highly predictive of relapse. There is a brief “window of opportunity” after day 50 and before day 200 post-HCT when most patients who will get aGVHD have experienced it, and the large majority of high-risk patients identified by MRD and aGHVD status have yet to relapse. It is imperative that novel post-HCT interventions be developed and given during this window in order to decrease relapse in the very high-risk patients we have defined. Disclosures: No relevant conflicts of interest to declare.