Abstract: Background : Approximately 45% of new ALL cases occur in adults ≥ 20 years of age (Howlader et al. SEER Cancer Statistics. 2015), and approximately 50% of adult patients relapse with poor subsequent outcomes (Oriol et al. Haematologica. 2010; Basson et al. JCO. 2011). Promising early efficacy and manageable safety were previously reported with anti-CD19 CAR T cells (KTE-C19) in adult patients with R/R ALL (Shah et al. ASCO 2017. #3024). Here we report updated results of the ZUMA-3 trial. Methods : Adult patients (≥ 18 years of age) with R/R ALL (Philadelphia+ eligible), & gt; 5% bone marrow (BM) lymphoblasts; Eastern Cooperative Oncology Group performance status (ECOG) 0-1; and adequate renal, hepatic, and cardiac function were eligible. Patients with active graft-versus-host disease or clinically significant infection were not eligible. Patients received a target dose of 1 × 106 CAR T cells/kg or 2 × 106 CAR T cells/kg after lymphodepletion with 25 mg/m2/day fludarabine for 3 days and 900 mg/m2/day cyclophosphamide given on the last day. The primary endpoint of phase 1 was incidence of dose-limiting toxicities (DLTs). Key secondary endpoints included incidence of adverse events (AEs), incidence of minimal residual disease-negative (MRD-) responses, duration of remission (DOR), relapse-free survival (RFS), and overall survival (OS). Exploratory endpoints included levels of anti-CD19 CAR T cells in blood and levels of cytokines in serum. Results : As of the data cut-off date (DCO; April 26, 2017), 22 patients have been enrolled, and 16 patients received KTE-C19 on study. Four patients had not received treatment by the DCO, 1 patient did not receive KTE-C19 due to an AE after conditioning, and 1 patient received KTE-C19 under compassionate use. All 16 patients who received KTE-C19 prior to the DCO were included in the safety analysis, and all patients who had the opportunity to be followed for 8 weeks prior to the DCO were included in the efficacy analysis (n = 11). Of the 16 patients dosed with KTE-C19, 63% were male, 56% had ECOG 1, and 50% had received ≥ 2 previous lines of treatment, including 3 patients with prior blinatumomab. Nineteen percent of patients had undergone prior allogeneic stem cell transplant, 31% had R/R to ≥ second-line therapy, 31% had primary refractory disease, and 19% experienced first relapse within 12 months of first remission. Most patients (81%) had baseline BM blasts ≥ 60%. Six patients received the 2 × 106 cells/kg dose and 10 received the 1 × 106 cells/kg dose. No DLTs were observed. One patient experienced a grade 5 event of cytokine release syndrome (CRS) at the 2 × 106 cells/kg dose, and no other KTE-C19-related grade 5 AEs were observed. In the 16 patients who received KTE-C19, all of whom were followed for at least 4 weeks, the most common grade ≥ 3 AEs were hypotension (56%), anemia (50%), pyrexia (50%), and decreased platelet counts (44%). Grade ≥ 3 CRS and neurologic events (NE) were reported in 25% and 63% of patients, respectively. Tocilizumab (toci) or steroids were given for AE management in 94% and 75% of patients, respectively. In the 11 patients eligible for the efficacy analysis, objective response rate was 82%, including 8 (73%) patients with a complete remission (CR or CR with partial hematopoietic recovery), and 1 (9%) with blast-free BM. All remissions were MRD- as determined by flow cytometry. All 5 (100%) of the other patients who were too early for inclusion in the efficacy analysis had MRD- bone marrow with varying degrees of count recovery at the time of the DCO. Median follow-up was 6.8 months; 4 patients relapsed 63 - 168 days after treatment with KTE-C19. Efficacy was comparable between patients who recieved KTE-C19 doses of 1 × 106 and 2 × 106 CAR T cells/kg. Data from additional patients, including those treated with a lower dose of 0.5 × 106 CAR T cells/kg, as well as updated safety, efficacy, biomarker, and product characteristic analyses across dosing groups will be presented. Conclusions : In this ongoing phase 1 study, KTE-C19 has shown promising efficacy in adult patients with R/R ALL. The safety profile was generally manageable and additional approaches to improve the benefit:risk profile are being explored. ZUMA-3 continues to enroll additional patients at the 0.5 × 106 CAR T cells/kg dose level. Disclosures Wierda: AbbVie: Consultancy, Honoraria, Research Funding; Karyopharm: Research Funding; Genentech/Roche: Consultancy, Honoraria, Research Funding; Merck: Consultancy, Honoraria; Juno: Research Funding; Pharmacyclics: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Kite: Research Funding; GSK/Novartis: Consultancy, Honoraria, Research Funding; Emergent: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Janssen: Research Funding; The University of Texas MD Anderson Cancer Center: Employment; Acerta: Research Funding. Oluwole: Kite Pharma: Membership on an entity's Board of Directors or advisory committees. Schiller: Kite Pharma: Research Funding. Topp: Regeneron: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Research Funding; Celgene: Other: Travel; Macrogenics: Consultancy, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, Research Funding. Kersten: Kite Pharma: Honoraria; Novartis: Honoraria; Roche: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Millenium/Takeda: Honoraria, Research Funding; Mundipharma: Honoraria; Gilead Sciences: Honoraria; BMS: Honoraria; MSD: Honoraria; Amgen: Honoraria. Mojadidi: Kite Pharma: Employment, Equity Ownership. Xue: Kite Pharma: Employment, Equity Ownership. Mardiros: Kite Pharma: Employment, Equity Ownership. Jiang: Kite Pharma: Employment, Equity Ownership. Shen: Kite Pharma: Employment, Equity Ownership. Aycock: Kite Pharma: Employment, Equity Ownership. Stout: Kite Pharma: Employment, Equity Ownership. Wiezorek: Kite Pharma: Employment, Equity Ownership. Jain: Kite Pharma: Employment, Equity Ownership.

Abstract: New therapies are needed for relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma. This phase 1b, open-label trial evaluated two anti-CD20-based triplet combinations. Methods Patients with R/R follicular lymphoma (FL; n  = 13) were treated with obinutuzumab, atezolizumab, and polatuzumab vedotin (G-atezo-pola; 1.4 mg/kg/1.8 mg/kg) and patients with R/R diffuse large B-cell lymphoma (DLBCL; n  = 23) received rituximab (R)-atezo-pola. The primary efficacy endpoint was complete response (CR) at end of induction (EOI) by PET-CT (investigator assessed; modified Lugano 2014 criteria). Safety endpoints were also assessed. Results 13 FL patients were treated and evaluable for safety; 2/23 DLBCL patients did not receive treatment and were not included in the safety population. Median observation time was 23.3 and 5.7 months in the FL and DLBCL cohorts, respectively. At EOI, CR rates in FL patients treated with G-atezo-pola at pola doses of 1.4 mg/kg ( N  = 3) and 1.8 mg/kg ( N  = 7) were 33% and 14%, respectively. In DLBCL patients receiving R-atezo-pola, the CR rate at EOI was 13%. In the FL cohort, 62% of patients experienced a grade 3–5 adverse event (AE; including two deaths) and 31% developed a serious AE (SAE). In DLBCL patients, R-atezo-pola was associated with a lower incidence of grade 3–5 AEs (24%; one death) and SAEs (10%). In both cohorts, the most common grade 3–5 AEs were hematologic toxicities. Conclusion Based on these safety issues, considered as related specifically to G-atezo-pola, and limited efficacy, no further development of either combination is planned. Trial registration NCT02729896; Date of registration: April 6, 2016.

Abstract: In the phase 3 TOWER study, exposure-adjusted AE rates were lower for blinatumomab vs SOC chemotherapy in Ph− B-cell r/r ALL patients. These data further support the role of blinatumomab as an efficacious and well-tolerated treatment option for B-cell r/r ALL patients.

Abstract: T cell–engaging immunotherapies exert unprecedented single-agent activity in multiple myeloma (MM), thereby putting a yet unexplored selective pressure on the clonal architecture. In this study, we report on homozygous BCMA (TNFRSF17) gene deletion after BCMA-targeting T cell–redirecting bispecific antibody therapy in a heavily pretreated MM patient. Loss of BCMA protein expression persisted over subsequent relapses, with no response to treatment with anti-BCMA antibody drug conjugate. In light of the multiple alternative targets that are emerging in addition to BCMA, we extended our analyses to delineate a more complete picture of genetic alterations that may have an impact on immunotherapy targets in MM. We performed whole-genome sequencing and RNA sequencing in 100 MM patients (50 were newly diagnosed; 50 were relapsed/refractory) and identified a significant proportion of patients with aberrations in genes encoding immunotherapy targets; GPRC5D ranked first with 15% heterozygous deletions, followed by CD38 (10%), SDC1 (5%), and TNFRSF17 (4%). Notably, these heterozygous deletions did not lower the expression levels of respective genes, but they may represent a first hit that drives the acquisition of homozygous deletions and subsequent antigen-loss relapse upon targeted immunotherapy. In summary, we show preexisting vulnerability in genes encoding immunotargets before and homozygous deletions after T cell–engaging immunotherapy.

Abstract: Patients with relapsed/refractory B‐cell precursor acute lymphoblastic leukemia who achieve full complete remission (CR), CR with partial hematologic recovery, or CR with incomplete hematologic recovery after treatment with blinatumomab can have a durable response with or without subsequent allogeneic hematopoietic stem cell transplantation (HSCT). In the current study, the best outcomes with blinatumomab are observed among patients who achieved minimal residual disease remission in first salvage therapy regardless of subsequent HSCT.

Abstract: Abstract 2880 Blinatumomab (MT103) is a single-chain bispecific antibody construct with specificity for CD19 and CD3 belonging to the class of bispecific T cell engager (BiTE®). We have previously reported that blinatumomab delivered as single agent to patients with relapsed NHL and B-precursor acute lymphoblastic leukemia by continuous intravenous (CIV) infusion over 4–8 weeks depleted peripheral B cells, expanded T effector cells, and resulted in clinical responses. In this phase I study 52 patients (41 males, 11 females) have been treated, 21 with FL, 21 with MCL and 10 with other subtypes of lymphoma (MZL, SLL, LPL, CLL). Patients have received a median of 3 prior regimens (range 1 to 12). Ninety percent of the patients had prior exposure to rituximab and 45% to fludarabine. Patients were treated at a dose range from 0.5 to 90 μg/m2/d. The most common adverse events (AEs) occurred early, were transient, reversible and did not require discontinuation of treatment. The most common clinical AEs regardless of causality were pyrexia (75%), headache (45%) and fatigue (37%). The most common laboratory abnormality AEs regardless of causality were lymphopenia (75%), leukopenia (57%), thrombocytopenia (39%), C-reactive protein increase (53%) and fibrin D dimer increase (37%). The medically most important AEs that resulted in permanent discontinuation were CNS events. Signs and symptoms observed included kinetic tremor, speech impairment, disorientation, apraxia and seizure. All CNS events were fully reversible without sequelae and no pathological findings by MRI imaging were reported. Out of the 52 patients treated, 9 had to discontinue treatment permanently in the first cycle due to these CNS events. At a dose of 90 μg/m2/d two DLTs were observed which were CNS events during the DLT period of the first 2 weeks of treatment. Therefore 60μg/m2/d is the currently recommended dose. A low B to T cell ratio ( 〈 1:8) determined by FACS analysis in peripheral blood was found to be a risk factor for CNS events. No CNS events requiring treatment discontinuation occurred in 32 out of 34 patients with a high B:T cell ratio (≥1:8) up to 60μg/m2/d. In the 18 patients with low B:T cell ratio, 7 had CNS events requiring treatment discontinuation. Patients with low B:T cell ratio were subsequently treated with an alternative dosing schedule in which reduced doses of either 5 and 15 μg/m2/d were sequentially administered for 1 week respectively followed by an increase to 60 μg/m2/d. First single-step dosing was applied. However, CNS events leading to treatment discontinuation were still observed. Therefore a double-step regimen was implemented; in the initial cohort of 3 patients with low B:T cell ratio there were no treatment discontinuations due to CNS events. Overall 18 patients with FL or MCL were treated with constant or step dosing regimens at or reaching 60 μg/m2/d dose level. Eight out of the 9 patients with constant dosing showed an objective response by Cheson criteria. All responders had a high B:T cell ratio. One patient with a low B:T cell ratio was discontinued due to a CNS AE. Six out of 9 patients with low B:T cell ratio enrolled for step dosing showed an objective response. One patient (single step dosing) discontinued treatment because of a CNS AE and 2 patients discontinued because of tumor progression. As of June 15th 2010, response duration ranged from 1 to 30+ months. Median for response duration was 26 months with 5 out of 14 responses ongoing. Table 1: Response evaluation in patients enrolled in 60 μg/m2/d cohorts. Dose Level Cohort Patients Complete Response Partial Response Overall Response FL MCL Total FL MCL Total FL MCL Total FL MCL Total 60 μg/m2/d Constant 6 3 9 2 1 3 4 1 5 6 2 8 5 or 15 then 60 μg/m2/d Single step 3 3 6 2 0 2 1 1 2 3 1 4 5/15/60 μg/m2/d Double Step 2 1 3 0 0 0 2 0 2 2 0 2 Total 11 7 18 4 1 5 7 2 9 11 3 14 These data confirm high single-agent activity of blinatumomab with long lasting remissions. Initial data with double step dosing demonstrate that this approach maintains clinical activity without discontinuations due to CNS AEs. Evaluation of safety and clinical efficacy of this uniform double step schedule including other subtypes of NHL is ongoing. Disclosure: Scheele: Micromet Inc.: Employment. Zugmaier:Micromet Inc.: Employment. Nagorsen:Micromet Inc.: Employment. Klinger:Micromet Inc.: Employment. Schmidt:Micromet Inc.: Employment. Klappers:Micromet. Inc: Employment. Kufer:Micromet Inc.: Employment. Bargou:Micromet Inc.: Consultancy.

Abstract: Introduction. Approximately 40% of patients (pts) with newly diagnosed AML either fail to achieve complete remission with intensive induction therapy or experience disease recurrence after a short remission (CR1 & lt;6 months). While these primary induction failure (PIF) and early relapse (ER) pts are treated collectively with late relapse (LR) pts (CR1 & gt;6 months), the probability of response for PIF/ER pts is particularly poor (~12%) with median expected overall survival of ~3.5 month and no approved therapy for this specific population. We have recently shown that increased immune infiltration of the tumor microenvironment (TME) is associated with induction failure and poor prognosis; conversely, an infiltrated TME predisposes for immunotherapy response1. We provide an update of the first-in-human study of flotetuzumab (FLZ), an investigational CD123 x CD3 bispecific DART® molecule currently in clinical development for PIF/ER AML pts. Methods. In this phase of the study, PIF is defined as being refractory to induction with: ≥1 high-intensity cytarabine-based chemotherapy (CTx) cycles, or ≥2 but ≤4 Bcl-2 inhibitor-based combinations, or gemtuzumab ozogamicin only. ER is defined as relapse following CR1 & lt; 6 months. Pts who receive up to one prior salvage attempt are included. Pts whose AML recurred following HSCT are excluded. The recommended Phase 2 dose (RP2D) of FLZ is 500 ng/kg/day administered as a continuous infusion in 28-day cycles following a step-up ('priming') lead-in dose during Cycle 1 Week 1. Disease status is assessed by modified IWG criteria. Duration of response is measured from initial response to relapse or death. Results. As of July 1, 2020, 38 PIF/ER (as defined above) AML patients have been treated at the RP2D (median age 63yrs [range 28-81]; 31.6% [12] pts female). Most pts (63.2%, 24/38) were PIF and the large majority (94.7%, 36/38) had non-favorable risk by ELN 2017 criteria (25 pts adverse, 11 pts intermediate); 34.2% (13/38) had secondary AML. For ER pts, median duration of CR1 was 2.9 months (range: 0.7-4.0 months). Cytokine release syndrome (CRS) was the most frequently reported treatment related adverse event (TRAE), with all pts experiencing mild-to-moderate (grade ≤ 2) CRS. No grade ≥ 3 CRS events have been reported in this cohort. Most CRS events (51.5%) occurred in the first week of treatment during step-up dosing. The incidence of CRS progressively decreased during dosing at RP2D (34.8% in week 2, 4.5% in week 3, and 6.1% in week 4), allowing outpatient treatment in most cases. Neurologic AEs have been infrequent, with the most prominent event being grade 1 or grade 2 headache in 23.7% (9/38) treated at the RP2D. Two pts experienced grade 3 confusion of short duration (1-2 days) that was fully reversible. Over half (57.9%) of pts had evidence of antileukemic activity (reduction in blast count) with a median decrease of 92.7% in BM blasts (Fig. 1). The overall complete response rate (CRR, & lt;5% bone marrow blast) was 42.1% (16/38; 7 CR, 4 CRh, 4 CRi, and 1 MLFS), with 68.8% (11/16) subsequently undergoing stem cell transplant. PIF pts showed a CRR of 45.8% (11/24; 5 CR, 3 CRh, and 3 CRi); CRR for ER pts was 35.7% (5/14; 2 CR, 1 CRh, 1CRi and 1 MLFS). Median time to first response was 1 cycle (range: 1-3 cycles). Sixty-nine percent (11/16) of responders normalized PB counts while on FLZ. Transfusion independence was achieved in 35.7% (10/28) of pts for whom data were available. Preliminary, median duration of response (mDOR) was 3.1 months (range 0.4-30.0 months) with many pts (29%, 11/38) still ongoing. With a median follow up time of 10.8 months, median overall survival (mOS) was 4.5 months (95% confidence interval [CI]: 2.9, 8.8). In pts that responded (CRR) the mOS was 7.7 months (95% confidence interval [CI] : 2.9, NA). Overall 6 and 12-month survival rates are 41 % (22.1%, 59.0%) and 24 % (6.1%, 42.5%), respectively. Conclusion: FLZ demonstrated encouraging activity in pts with PIF/ER AML, a population with poor prognosis and high unmet medical need, with 42.1% achieving CRR and over half of those receiving a stem cell transplant. Treatment is tolerable with a minimum 8 day inpatient treatment. The study is currently enrolling patients [NCT02152956] 1 Vadakekolathu J, Minden MD, Hood T, Church SE, Reeder S, Altmann H et al. Immune landscapes predict chemotherapy resistance and immunotherapy response in acute myeloid leukemia. Sci Trans Med 2020. Disclosures Aldoss: abbvie: Consultancy, Research Funding; agios: Honoraria; kite: Consultancy; autolus limited: Consultancy; JAZZ: Honoraria, Speakers Bureau; Amgen: Consultancy; Agios: Consultancy. Uy:Genentech: Consultancy; Agios: Consultancy; Pfizer: Consultancy; Jazz Pharmaceuticals: Consultancy; Daiichi Sankyo: Consultancy; Astellas Pharma: Honoraria. Emadi:Amgen: Membership on an entity's Board of Directors or advisory committees; NewLink Genetics: Research Funding; Jazz Pharmaceuticals: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; KinaRx: Other: co-founder and scientific advisor; Servier: Membership on an entity's Board of Directors or advisory committees. Walter:Aptevo Therapeutics: Research Funding. Foster:Daiichi Sankyo: Consultancy; Bellicum Pharmaceuticals: Research Funding; Macrogenics: Consultancy, Research Funding. Arellano:Hanmi: Research Funding; Gilead Sciences, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cephalon Oncology: Research Funding. Wieduwilt:Amgen: Research Funding; Macrogeneics: Research Funding; Leadiant: Research Funding; Merck: Research Funding; Shire: Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees. Michaelis:Jazz Pharmaceuticals: Research Funding. Stiff:Kite, a Gilead Company: Research Funding; Gamida Cell: Research Funding; Atara: Research Funding; Unum: Research Funding; Delta-Fly: Research Funding; Macrogenics: Research Funding; Amgen: Research Funding. Advani:Novartis: Consultancy, Other: advisory board; Pfizer: Honoraria, Research Funding; Takeda: Research Funding; OBI: Research Funding; Kite: Other: Advisory board/ honoraria; Amgen: Consultancy, Other: steering committee/ honoraria, Research Funding; Seattle Genetics: Other: Advisory board/ honoraria, Research Funding; Immunogen: Research Funding; Glycomimetics: Consultancy, Other: Steering committee/ honoraria, Research Funding; Macrogenics: Research Funding; Abbvie: Research Funding. Wermke:MacroGenics: Honoraria. Erba:AbbVie, Daiichi Sankyo, Forma, ImmunoGen, Jazz Pharmaceuticals, MacroGenics, Novartis, PTC: Research Funding; Glycomimetics: Other: member of Scientific Steering Committee; Celgene: Other: chair of the Scientific Steering Committee; Covance (AbbVie): Other: chair of the Independent Review Committee; AbbVie, Agios, Celgene, Incyte, Jazz Pharmaceuticals, and Novartis: Speakers Bureau; AbbVie, Agios, Amgen, Astellas, Celgene, Daiichi Sankyo, Glycomimetics, ImmunoGen, Incyte, Jazz Pharmaceuticals, MacroGenics, Novartis, and Pfizer: Consultancy. Topp:Amgen, Boehringer Ingelheim, KITE, Regeneron, Roche: Research Funding; Amgen, KITE, Novartis, Regeneron, Roche: Consultancy. Ravandi:Abbvie: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Celgene: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria; Orsenix: Consultancy, Honoraria, Research Funding. Muth:MacroGenics, Inc.: Current Employment, Current equity holder in publicly-traded company. Collins:IQVIA: Other: I have worked as a contractor for IQVIA in the past, within the past 24 months.; MacroGenics: Current equity holder in publicly-traded company, Other: I currently work as a contractor for MacroGenics. Guo:Macrogenics: Current Employment. Tran:MacroGenics: Current Employment. Kaminker:MacroGenics, Inc.: Current Employment, Current equity holder in publicly-traded company. Patel:MacroGenics: Current Employment. Bakkacha:MacroGenics: Current Employment. Jacobs:MacroGenics: Current Employment. Seiler:MacroGenics: Current Employment. Rutella:Kura Oncology: Research Funding; MacroGenics Inc.: Research Funding; NanoString Technologies Inc.: Research Funding. Bonvini:MacroGenics, Inc.: Current Employment, Current equity holder in publicly-traded company. Davidson-Moncada:Macrogenics: Current Employment. DiPersio:Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees.