ALBERT

Description: Background: Infusion of chimeric antigen receptor modified T cells targeting the CD30 molecule and encoding the CD28 endodomain (CD30.CAR-Ts) in the absence of lymphodepleting chemotherapy has been shown to be safe with responses seen in patients (pts) with relapsed/refractory (r/r) CD30+ lymphomas (Ramos et al., JCI 2017). We present here the results of a phase 1b/2 trial of CD30.CAR-Ts administered after lymphodepleting chemotherapy in pts with r/r CD30+ Hodgkin (HL) and Non-Hodgkin lymphoma (NHL). Methods: The primary objective of the phase 1b portion of the study was to determine the recommended phase 2 dose level (RP2DL) of CD30.CAR-Ts using a standard 3+3 design. Two dose levels were tested: 1 x 108 CAR-Ts/m2 (DL1) and 2 x 108 CAR-Ts/m2 (DL2). For lymphodepletion, the first 8 pts (including the first 3 pts treated at DL1) received 2 days of bendamustine (benda) 90 mg/m2, while the 10 remaining pts received 3 days of benda 70 mg/m2 and fludarabine (flu) 30 mg/m2, except for one pt who received only 1 day of benda and flu due to possible benda toxicity. Inclusion criteria were age ≥ 18 years, CD30+ disease, and r/r HL or NHL having failed ≥2 prior therapies. Results: At the time of data cut off (7/1/2018), 18 pts with a median age of 40.5 years (range: 23-70) had received CD30.CAR-Ts and undergone response assessment. Sixteen pts had HL, 1 had enteropathy associated T cell lymphoma, and 1 had Sezary syndrome. All pts were heavily pre-treated with a median of 8.5 prior therapies (range: 4-17). All pts had received prior brentuximab vedotin and 13 had prior checkpoint inhibitor therapy. Fourteen pts had prior autologous stem cell transplant (SCT) and 7 had prior allogeneic SCT. Treatment was well tolerated with no dose limiting toxicities; as a consequence, the highest dose level of CAR-T cells (2 x 108 CAR-Ts/m2) was given as the RP2DL. Three pts developed cytokine release syndrome (CRS) (grade 1: 2 pts and grade 2: 1 pt). Grade 1 CRS resolved spontaneously, while the pt with grade 2 CRS responded to tocilizumab. No neurotoxicity was observed. Out of the 18 pts, 4 were in a complete response (CR) before infusion due to bridging chemotherapy and remained disease free at 6 wk follow up. Two of these pts have since relapsed with PFS of 3.8 months and 11.9 months while the other 2 pts are still in CR after 1 year of follow up. The 14 pts with evidence of disease pre-lymphodepletion were included in efficacy analysis. Of these 14 pts, 6 had a CR (43%, all in the benda/flu cohort), 1 had partial response (7%), 2 had stable disease (14%) and 5 had progressive disease (35%) at disease assessment. No responses occurred in the 3 pts treated at DL1. At median follow up of 138 days, the median PFS was 129 days. The median PFS for the 3 evaluable pts who received benda at DL1 was 55 days vs 172 days for the 9 pts who received benda/flu at DL2 (p = 0.039). The median PFS for the 2 evaluable pts at DL2 who received benda lymphodepletion was 85.5 days but this was not included in the comparison due to small sample size. Two out of 14 evaluable pts remain in CR at 1 year. Using PCR on peripheral blood, CD30.CAR-Ts were found to be increased in the circulation of all pts, peaking at wk 2 post infusion, with increasing CAR-T cells in pts receiving greater number of CAR-T cells or more robust lymphodepletion (3.4x103 ± 2.9x103 copies/ug of DNA for DL1-beda vs. 61x103 ± 41x103 for DL2-benda vs. 59x103 ± 22x103 for benda/flu). These differences were confirmed by flow cytometry (CD3+CAR+ cells = 13%±9% for DL1-benda vs 21%±10% for DL2-benda vs 35%±8% for benda/flu). Persistence was also related to dose level and lymphodepletion (0.06x103 ± 0.01x103 vs 0.44x103 ± 0.41x103 vs 28x103 ± 15x103/ug of DNA at wk 4 for DL1-benda, DL2-benda, and benda/flu, respectively). Although both lymphodepletion regimens reduced the lymphocyte counts, only the combination of benda/flu was found to have a significant increase in IL-15 and IL-7 cytokines (13 fold, p

Description: Background: Pediatric hospital-acquired venous thromboembolism (HA-VTE) incidence is rising but remains relatively low overall, requiring risk stratification to reduce unnecessary thromboprophylaxis exposure. Large sample sizes are needed for prospective epidemiologic risk factor studies, necessitating collaboration. Objectives: We formed the multi-institutional Children's Hospital-Acquired Thrombosis (CHAT) web-based registry via Research Electronic Data Capture (REDCap) to identify independent HA-VTE risk factors for future clinical risk score development. Methods: This IRB-approved, retrospective chart review reveals HA-VTE risk factors from patients aged 0-21 years who developed diagnostically-validated VTE more than 48 hours after hospital admission, or after central venous line placement, at 3 pediatric hospitals from January 2012 - December 2014. We used descriptive statistics to summarize demographics, medical comorbidities and types of any applicable central lines for the initial 373 patients entered into the database, as well as characteristics of the VTEs themselves and associated laboratory testing. Further analysis is currently underway utilizing matched controls and logistic regression to identify specific odds ratios for independent risk factors. Results: The median length of time to VTE diagnosis was 9 with interquartile range (IQR) of day 4-18, 35.3% of VTE occurred in a critical care unit, and 21% were incidentally found. The distribution of VTE included deep vein thromboses (DVT) of the arms/legs (81.1%) followed by cerebral sinus venous thrombosis (7.3%), pulmonary embolism (5.4%), DVT of the abdomen (4%), and intracardiac DVT (4%) with some overlap due to patients with multiple, separate, concurrent VTE events. Demographic characteristics of the initial 373 subjects revealed median age of 3.7 years (IQR of 0.4 years to 13.8 years) at VTE diagnosis and a slight male predominance (57.4%). 62.6% of patients had significant past medical history (Figure 1) and 8% were immobile at baseline. Evaluation of hospital course revealed a multitude of acquired putative risk factors for HA-VTE (Figure 2). 75.7% of VTE were associated with a central venous catheter (CVC). Of CVC-related VTE, 72% were in the same vein as CVC, 20% were in a vein which previously held a CVC, 3.6% surrounded the CVC tip, 2.9% occurred in a vein where CVC placement was attempted but unsuccessful. 59% of patients had at least one documented infection during hospitalization, 48% of patients had surgery, 5.5% of patients underwent trauma prior to admission, and 59.7% (n=221) of patients were intubated at some point during their admission with 86.9% (n=192) of those patients developing VTE after a minimum of 24 hours of mechanical ventilation. Laboratory testing of hospitalized patients revealed 51.2% of patients had a d-dimer level obtained at time of VTE and 97.8% of those patients had an elevated level. 44% of patients had at least one thrombophilia lab test ordered. Conclusions: The initial CHAT database results demonstrate a slight male predisposition and multiple associated chronic medical illnesses and acquired hospital course co-morbidities, particularly CVCs which were involved in three-fourths of VTE events. Ongoing work includes incorporating additional institutions and utilizing control subjects to identify independent risk factors for the development of a risk score model. Long-term goals include prospective validation of the scoring system in a cohort of patients from pediatric centers not involved in development of the risk score with the ultimate plan of using the scoring system to stratify patients for future randomized clinical trials of risk-based prevention strategies to evaluate the safety and efficacy of this approach for reduction of pediatric HA-VTE incidence without unnecessary thromboprophylaxis exposure. Figure 1. Distribution of past medical history Figure 1. Distribution of past medical history Figure 2. Prevalence of acquired risk factors. *Some patients with more than 1 documented infection. ^Procedures included: dialysis, plasmapheresis, cardiac catheterization, stent placement, coiling procedure. Figure 2. Prevalence of acquired risk factors. *Some patients with more than 1 documented infection. ^Procedures included: dialysis, plasmapheresis, cardiac catheterization, stent placement, coiling procedure. Disclosures Young: Kedrion: Consultancy; Biogen Idec: Consultancy, Honoraria; Novo Nordisk: Consultancy, Honoraria; Bayer: Consultancy; Baxter: Consultancy.

Description: The presence of MRD in patients with acute myeloid leukemia (AML) who are in morphologic remission has been shown to be a powerful predictor of eventual relapse. FMS-like tyrosine kinase 3 internal tandem duplications (FLT3-ITD) confer a negative prognostic impact by increasing the risk of relapse. However, the ability to detect these mutations in remission bone marrow specimens is hampered by the limited sensitivity of conventional polymerase chain reaction (PCR)-based assays, which detect approximately only 1 of every 100 (1%) mutant cells. To address this problem, we have developed a novel NGS-based MRD assay for the detection of FLT3-ITD mutations. Using isolated genomic DNA from bone marrow aspirates or whole-blood samples, PCR primers flanking exons 14 and 15 of the FLT3 gene were designed and highly diverse NGS libraries were generated. These libraries were then sequenced by Illumina's sequencing-by-synthesis method. The bioinformatics approach we used identifies unique FLT3-ITD mutations of varying length along with wild type sequences and calculates a mutant allelic frequency. The assay was validated using clinical samples to assess accuracy and reproducibility. DNA samples from selected mutant cell lines representing different FLT3-ITD lengths were spiked into normal DNA to evaluate assay sensitivity and linearity. The assay was linear (R2 = 0.958) down to FLT3-ITD allele frequency levels of 0.035% but was capable of detecting FLT3-ITD mutations at a level as low as 0.003%. We next validated the assay using clinical samples from patients with FLT3-ITD AML. The negative prognostic impact of FLT3-ITD mutations can be mitigated in part when an FLT3 inhibitor is administered in combination with induction chemotherapy, as demonstrated in CALGB10603/RATIFY (N Engl J Med. 2017;377:454). It was reported in this study that patients treated with an FLT3 inhibitor combined with chemotherapy followed by allogeneic transplant in first remission had better overall survival than their counterparts in the control arm. One hypothesis for this outcome is that the FLT3-inhibitor-treated patients had a lower leukemic burden prior to transplant. As a pilot test of this concept, we used our MRD assay on a series of bone marrow aspirate samples collected from 10 patients with newly diagnosed FLT3-ITD AML. The patients were selected to be as uniform as possible. All patients had intermediate-risk karyotype, a detectable FLT3-ITD mutation by conventional PCR, and mutated NPM1. All patients received cytarabine-based intensive induction and achieved morphologic first remission with a single course of chemotherapy. Finally, all patients underwent allogeneic transplant in first remission. The sample analyzed for MRD was the first collected after remission induction, 5-8 weeks after the start of therapy. The investigators performing the MRD assay were blinded to the clinical data. Four patients received chemotherapy alone, while 6 were treated with chemotherapy (7+3) plus an FLT3 inhibitor. In all patients' remission samples, the MRD assay identified the FLT3-ITD mutation that precisely matched the one observed in the original diagnostic specimen. This demonstrates the sensitivity of the assay (all samples had a detectable mutation), and the unique length of each patient's mutation confers a degree of specificity not achievable with MRD detection methods that focus on other AML-associated mutations. Supporting our hypothesis was the observation that patients treated with FLT3 inhibitors had MRD levels lower than those in patients treated with chemotherapy alone (Figure). Our results help establish the role of NGS-based MRD assays for the clinical management of FLT3-ITD AML. This assay could be used to define the depth of remission, identify persistent disease, and help guide decision making in the use of FLT3 inhibitors as continuation therapy. This study provides validation of the clinical utility of our MRD assay, which will be used to analyze the remission samples from patients in the ongoing phase 3, randomized, double-blind, placebo-controlled QuANTUM-First clinical trial, in which patients with newly diagnosed FLT3-ITD AML are randomized to receive either the highly potent and selective FLT3 inhibitor quizartinib or placebo in combination with chemotherapy, followed by single-agent quizartinib as continuation therapy. Disclosures Shi: Novartis: Employment, Equity Ownership; Daiichi Sankyo: Other: Provide clinical trial testing services. Chang:Daiichi Sankyo: Employment. Laing:Novartis: Employment; Daiichi Sankyo: Other: Provide clinical trial testing services. Berisha:Daiichi Sankyo: Employment. Adams:Johns Hopkins University: Employment. Ding:Navigate BP: Employment; Daiichi Sankyo: Other: Provide clinical trial testing services. Nakamaru:Daiichi Sankyo: Employment. Lameh:Navigate BioPharma Inc,: Employment; Daiichi Sankyo: Other: Provide clinical trial testing services. Pollner:Navigate BioPharma Inc.: Employment. Kobayashi:Daiichi Sankyo: Employment.

Description: Key Points Bispecific antibodies binding CD3 and CLL-1 deplete CLL-1+ target cells in animal models. An appropriately engineered CLL-1/CD3 bispecific antibody could be effective in treating AML.

Description: Background - Hospital-acquired venous thromboembolism (HA-VTE), comprised of deep vein thrombosis and pulmonary embolism, is associated with significant mortality and morbidity and the overall incidence is rising, leading to its recognition as a leading quality and patient safety concern in pediatric hospitals. Risk-based prophylactic strategies are used in adults but a paucity of high quality evidence exists regarding the safety and efficacy of these interventions in the pediatric population. Defining an objective assessment of VTE risk to guide standard approaches to the use of mechanical and/or pharmacologic prophylaxis (in the absence of contraindications) is a desirable strategy to decrease HA-VTE incidence while minimizing potential risks associated with prophylaxis. Methods- With Institutional Review Board approval, we retrospectively evaluated electronic health record data from 39 patients age 0-21 years (inclusive) who developed VTE more than 48 hours after admission to Children's Hospital Colorado (Aurora, CO, USA) from January 1, 2014 - December 31, 2014. We identified purported HA-VTE cases via ICD-9 discharge diagnosis codes, then two different reviewers cross-referenced and validated with pharmacy and radiology records. We evaluated the HA-VTE patient's VTE risk scores (high, moderate, or low) using our institutional VTE prevention clinical care guideline (CCG) at discrete time points prior to clot diagnosis, as well as whether the patient received mechanical and/or pharmacologic thromboprophylaxis. Objectives: We sought to determine the ability of our CCG to accurately assess HA-VTE risk prior to clot development and to assess the utilization and timing of thromboprophylaxis. Results: Of the 39 patients who developed a HA-VTE during the study period, CCG-based risk assessment on the day before the event had identified four (10.3%) patients as low risk, two (5.1%) as moderate risk, and 33 (84.6%) as high risk, as seen in Table 1. This distribution represents an overall increase in risk score compared to those determined on admission when 13 (33.3%) were low risk, 4 (10.3%) were moderate risk, and 22 (56.4%) were high risk. Admission risk scores tended to hold steady or increase during the hospitalization (Figure 1) and only one patient experienced a decrease in risk level prior to HA-VTE diagnosis. HA-VTE patients often had high risk scores as early as seven or even 14 days prior to the event, and 20 (51%) of the patients who developed HA-VTE were high risk during the entire admission. Of the HA-VTE patients, 19 (48.7%) were receiving thromboprophylaxis on the day prior to the event. 4 (21.1%) received pharmaceutical type only, 12 (63.2%) received mechanical type only, and 3 (15.8%) received both types. Conclusion: Institutional CCGs can be used to determine HA-VTE risk stratification in hospitalized children, thereby informing decisions regarding initiation of thromboprophylaxis as a preventative strategy in the absence of contraindications. Comparison to a group of age group- and risk level-matched control patients who did not develop HA-VTE is underway and will give appropriate context to the high risk designation as it pertains to HA-VTE incidence and the impact of thromboprophylaxis strategies. Table 1. Risk scores prior to HA-VTE diagnosis: Risk scores at various time points during hospitalization Risk Level Risk Score on Admission Risk Score 14 Days Prior Risk Score 7 Days Prior Risk Score 1 Day Prior Risk Score Day of VTE Low 13 (33.3%) 0 (0%) 2 (10.5%) 4 (10.3%) 4 (10.3%) Moderate 4 (10.3%) 1 (9.1%) 1 (5.3%) 2 (5.1%) 2 (5.1%) High 22 (56.4%) 10 (90.9%) 16 (84.2%) 33 (84.6%) 33 (84.6%) Total 39 11 19 39 39 Figure 1. Patient-level risk score tracking: Each colored line represents a unique HA-VTE patient's risk score trajectory during hospitalization. Risk scores upon admission correspond to days represented by negative numbers denoting various days prior to event (Day 0), and all patients have evaluations from 14, 7, and 1 day prior to the event, if applicable. Figure 1. Patient-level risk score tracking: Each colored line represents a unique HA-VTE patient's risk score trajectory during hospitalization. Risk scores upon admission correspond to days represented by negative numbers denoting various days prior to event (Day 0), and all patients have evaluations from 14, 7, and 1 day prior to the event, if applicable. Disclosures Off Label Use: We may discuss use of heparin (unfractionated or low molecular forms) for VTE thromboprophylaxis in children.

Description: Background: The safety and efficacy of treating pts with relapsed/refractory (r/r) CD30+ lymphomas with chimeric receptor modified T cells targeting the CD30 molecule (CD30.CAR-T) has been recently demonstrated (Grover et al., ASH 2018). Expression of PD-1 on CD30.CAR-T cells has been observed post-infusion at the time of disease recurrence. To determine the safety and efficacy of anti-PD-1 mAb therapy (CPI) post CD30.CAR-T cell therapy, we present a retrospective cohort review of pts with r/r Hodgkin lymphoma (HL) who subsequently received CPI after CD30.CAR-T progression. Methods: We followed and analyzed the clinical outcome of 5 pts with r/r HL who progressed after CD30.CAR-T cell therapy at the University of North Carolina at Chapel Hill and subsequently received CPI to treat relapsed disease. Clinical responses in follow up were determined per local radiologist assessment. Results: Prior to CAR-T cell therapy, the average age of the pts in this cohort was 36 years old (range, 26-54). Four of the five had been treated with CPI prior to CD30.CAR-T therapy, with a median duration of response of 224 days (range, 81-280) and best objective response being a partial response (PR) for all 4 pts. The median time from CPI to CD30.CAR-T therapy was 483 days (range, 25-1174 days). A total of 5 pts have been treated with CPI following clinical progression after CD30.CAR-T. All pts were heavily pre-treated with a median of 8 therapies prior to CD30.CAR-T. One pt received a second infusion of CD30.CAR-T after having stable disease (SD) 6 weeks following the first infusion. Following CD30.CAR-T infusion, 1 pt initially had a complete response (CR), 1 pt had a PR, 2 pts had stable disease (SD), and 1 pt had progressive disease (PD). All 5 pts subsequently developed PD. The median time from CD30.CAR-T to CPI was 132 days (range, 67-393 days), (Table 1). Of the 5 pts evaluable for response, 4 pts achieved a CR and 1 pt achieved a PR (Figure 1). At the time of data cutoff, the median duration of response was 212 days (range 139-836) with ongoing response in 3 pts. Two pts developed recurrent disease following CPI and were again treated with CD30.CAR-T cell therapy, achieving a 2nd CR in both cases. CPI use was associated with the expected toxicities. One pt developed neuropathy, leading to therapy discontinuation after 8 months of therapy. Another pt developed grade 3 colitis, resulting in discontinuation of therapy after 25 months of therapy. A third pt developed pneumonitis (prior mediastinal radiation), with discontinuation of therapy after 8 months of therapy. All pts were still alive at last follow up with a median overall survival of 2.44 years (range, 0.93-2.76) from initial CD30.CAR-T cell therapy. Conclusion: To our knowledge, this is first report of pts with r/r HL who received CPI after CD30.CAR-T cell therapy. Though limited by size, this cohort demonstrates clinical efficacy of CPI after CD30.CAR-T even in those pts who had progressed after previous treatment with CPI. All pts achieved an objective response with CPI administered for relapsed disease after CD30.CAR T cell therapy. Four of five of these patients achieved a CR and 3 patients achieved an improved response when compared to CPI prior to CD30.CAR-T. Combination of CPI and CD30.CAR-T may be an attractive study design in the future for r/r HL. Disclosures Grover: Seattle Genetics: Consultancy. Park:BMS: Consultancy, Research Funding; Rafael Pharma: Membership on an entity's Board of Directors or advisory committees; G1 Therapeutics: Consultancy; Teva: Consultancy, Research Funding; Gilead: Speakers Bureau; Seattle Genetics: Research Funding, Speakers Bureau. Savoldo:Baylor College of Medicine: Patents & Royalties: CAR.CD30 patent; Bluebirdbio: Other: research agreement; Cell Medica: Other: Research Agreement; Bellicum: Other: Research Agreement. Serody:Merck: Research Funding; GlaxoSmithKline: Research Funding.