a phase 1 study of flotetuzumab, a cd123 x cd3 dart ... · a phase 1 study of flotetuzumab, a cd123...

A Phase 1 Study of Flotetuzumab, a CD123 x CD3 DART ® Protein, Combined with MGA012, an Anti-PD-1 Antibody, in Patients with Relapsed or Refractory Acute Myeloid Leukemia Andrew H. Wei 1 , Chun Yew Fong 2 , Pau Montesinos 3 , Maria Calbacho 4 , Jordi Sierra 5 , Jaime Perez De Oteyza 6 , Jacob M. Rowe 7 , Ofir Wolach 8 , Yishai Ofran 9 , Yakir Moshe 10 , Jichao Sun 11 , Jan Baughman 11 , Eileen McNulty 11 , Ezio Bonvini 11 , Jon M. Wigginton 11 ; and Jan K Davidson-Moncada 11 1 The Alfred Hospital, Melbourne, VIC, Australia; 2 Department of Clinical Haematology, Austin Health and Olivia Newton John Cancer Research Institute, Melbourne, Australia; 3 Hospital Universitari i Politècnic La Fe, Valencia & CIBERONC, Instituto Carlos III, Madrid, Spain; 4 Hematology and Hemotherapy, Hospital 12 de Octubre, Madrid, Spain; 5 Hematologia Clínica, Hospital de la Santa Creu i de Sant Pau, Barcelona, Spain; 6 Hospital Universitario Sanchinarro, Madrid, Spain; 7 The Ruth and Bruce Rappaport Faculty of Medicine, Shaare Zedek Medical Center, Jerusalem, Israel; 8 Sackler Faculty of Medicine, Tel Aviv University, Petah Tikva, Israel; 9 Ramban Health Care Campus, Haifa, Israel; 10 Sackler faculty of Medicine, Tel Aviv University, Department of Hematology, Tel Aviv (Sourasky) Medical Center, Tel Aviv, Israel; 11 MacroGenics, Inc., Rockville, MD ©2019 MacroGenics, Inc. All rights reserved. Presented at the 61 st American Society of Hematology Annual Meeting, December 7–10, 2019, Orlando, FL 2662 Study Design Induction LID 1 8 15 22 28 NOTE: One cycle only Consolidation 1 8 15 22 28 NOTE: One cycle only 2 nd Induction 1 8 15 22 28 NOTE: Flotetuzumab via continuous infusion. Continue combination therapy up to 5 cycles, meet criteria for CRx, CRi, CRh, or MLFS, or criteria for discontinuation Extended MGA012 Phase 1 8 15 22 28 NOTE: ≤ 12 cycles MGA012 Flotetuzumab lead-in dose LID Flotetuzumab CRx, CRi, CRh, or MLFS CR, SD, PD Key Eligibility Criteria Inclusion ■ Confirmed diagnosis of primary or secondary AML (any subtype except acute promyelocytic leukemia) according to WHO classification ■ Patients with AML must be unlikely to benefit from cytotoxic chemotherapy defined by any one of the following criteria: – Leukemia refractory to ≥ 2 induction attempts – Leukemia in 1st relapse with initial CR duration < 6 months – Leukemia in 1st relapse following ≥ 1 unsuccessful salvage attempts – Leukemia in 2nd or higher relapse ■ Prior treatment failure with at least 4 cycles of a hypomethylating agent ■ Eastern Cooperative Oncology Group performance status of ≤ 2 ■ Life expectancy ≥ 4 weeks ■ Peripheral blast count ≤ 20,000/mm 3 at the time of initiation of infusion on Cycle 1 Day 1 ■ Acceptable laboratory parameters and adequate organ reserve Exclusion ■ Prior treatment with an anti-CD123-directed agent, with the exception of patients who have failed or relapsed after treatment with monotherapy flotetuzumab on Protocol CP-MGD006-01 (NCT02152956) ■ Need for concurrent other cytoreductive chemotherapy ■ History of known or suspected autoimmune disease with the specific exceptions of vitiligo, resolved childhood atopic dermatitis, psoriasis not requiring systemic treatment (within the past 2 years), and patients with a history of Grave’s disease that are now euthyroid clinically and by laboratory testing ■ Previous treatment with radiotherapy, cytotoxic chemotherapy, immunotherapeutic agents, investigational agent, excluding prior flotetuzumab, in the 2 weeks prior to study drug administration; use of immunosuppressant agents in the 2 weeks prior to study drug administration ■ Known central nervous system leukemia References 1. Vergez et al. Haematologica. 2011 Dec;96(12):1792-8. 2. Root et al. Antibodies. 2016 5(1), 10.3390/antib5010006. 3. Godwin et al. ASH 2019. 4. Rutella et al. ASH 2018. 5. Uy et al. ASH 2018. 6. Mehnert et al. SITC 2019. 7. Rao et al. SITC 2019. Rationale PD-1/PD-L1 Axis Blockade Enhances Flotetuzumab Anti-leukemic Activity In Vitro In vitro studies have shown synergistic T-cell mediated cytotoxicity of an AML cell line (KG1A) with flotetuzumab in the presence of PD-1/PD-L1 axis blockade compared to flotetuzumab alone 0 0.1 0 25 50 75 100 Flotetuzumab (ng/mL) Viable Cells (%) PBS ISO anti-PD-L1* anti-PD-1* *statistically significant (p<0.05). KG1A cells incubated with human T cells at E:T ratio 0.25:1 in the presence of flotetuzumab ± 10 μg/mL anti-checkpoint antibody. MGA012* Investigational anti-PD-1 antibody that has shown evidence of clinical activity in Phase 1 and 2 studies 6 *Also known as INCMGA00012. 80 -80 20 - 30 60 -60 40 -40 20 -20 0 100 Best Percentage Change From Baseline PD PD PD PD PD PD SD PD SD PD PR PD PR PR PD PD SD PD PD SD Out of 26 evaluable patients with locally advanced or metastatic squamous carcinoma of the anal canal, 6 did not have any baseline or postbaseline tumor assessments. Upper limit of dotted line indicates a criterion for PD (≥ 20% increase in sum of target lesion diameters) and lower limit indicates a criterion for PR (≥ 30% decrease in sum of target lesion diameters). PD, progressive disease; PR, partial response; SD, stable disease. Flotetuzumab combination with CPI aims to obviate flotetuzumab-induced pathways of AML resistance and harness flotetuzumab-induced positive changes of immune modulation ■ Flotetuzumab leads to T-cell activation, which in turn was associated with PD-1 induction on T lymphocytes, enhanced IFNγ secretion, and upregulation of PD-L1 expression by AML blasts 4,5 ■ Residual bone marrow AML blasts show higher expression of PD-L1 positive compared to baseline ■ Enhanced PD-L1 expression by AML blasts was associated with reduced flotetuzumab activity in vitro and in vivo ■ In vitro studies have shown synergistic T-cell mediated cytotoxicity of an AML cell line (KG1A) with flotetuzumab in the presence of PD-1/PD-L1 axis blockade compared to flotetuzumab alone ■ MGA012 is an anti-PD-1 antibody that has shown clinical activity in Phase 1 and Phase 2 studies 6,7 ■ We hypothesize that combined checkpoint inhibition with MGA012 together with redirected T-cell killing of CD123+ cells with flotetuzumab may show enhanced activity over flotetuzumab alone Background ■ Acute myeloid leukemia (AML) blasts and leukemic stem and progenitor cells typically express higher levels of CD123 than their normal hematopoietic stem cell counterparts, making CD123 an attractive target ■ Leukemic CD123 expression is associated with poor prognosis, high-risk disease, and increased risk of induction failure 1 ■ Single-agent flotetuzumab, an investigational CD123 x CD3 bispecific DART protein, has shown evidence of clinical activity in a Phase 1 study of relapsed/ refractory (R/R) AML Flotetuzumab (MGD006): CD123 x CD3 Bispecific DART ® Protein ■ Flotetuzumab: – An investigational bispecific molecule that co-engages T cells (anti-CD3) with a tumor associated antigen (CD123) – Designed to: – Redirect T cells to kill tumor cells – Recognize tumors independent of TCR and MHC – Currently being tested in a Phase 1/2 study in AML ■ CD123, the low-affinity IL-3 receptor (IL3Rα) – Normally expressed on plasmacytoid dendritic cells (pDCs), basophils, monocytes, and hematopoietic progenitor cells (HPCs) – Over-expressed on leukemic stem cells (LSCs) in AML and other hematologic malignancies Anti-CD3 Anti-CD123 Chain 1 Chain 2 VH1 VL2 VH2 VL1 Cys -COOH Cys -COOH Target Ag DART Crystal Structure 2 H 2 N H 2 N VL VH VH VL NH 2 NH 2 S–S COOH COOH Anti-CD3 T-cell Infiltration in the Bone Marrow of a Flotetuzumab- treated Patient 3 CD123 DAPI CD3 CD123 DAPI Baseline Flotetuzumab (Cycle 1) Single-agent Flotetuzumab Has Shown Evidence of Clinical Activity in a Phase 1 Study of Refractory AML 350 100 75 50 25 0 -25 -50 -75 -100 Bone Marrow Blast Change from Baseline (%) CR: 5 (17.9%) CR/CRh: 8 (28.6%) CR/CRh/CRi*: 9 (32.1%) ORR (CR/CRh/CRi/MLF/PR): 9 (32.1%) *Four of the responders (2 CR, 1 CRh and 1 CRi) received allo-HSCT consolidation 300 30 pts treated at RP2D: 28 response evaluable, 24 pts in waterfall plot, 4 PD on PB blasts, 2 non-evaluable pts (1 pt withdrew consent, 1 pt withdrawn due to non-TRAE). CR: complete response; CRh: complete response with partial hematological recovery; CRi: complete response with incomplete hematological improvement. (CP-MGD006-01, NCT02152956). Data cut-off November 1, 2019. In Vitro Upregulation of Checkpoint Molecules by Flotetuzumab Upregulation of PD-1 on CD4 and CD8 T cells and of other checkpoint molecules on AML blasts upon co-incubation with flotetuzumab 0 10 3 10 4 10 5 0 10 3 10 4 10 5 0 10 3 10 4 10 5 BL 500 50 5 CD4 gate CD3 gate CD8 gate MGD006 (ng/mL) PD-1 IFNγ (pg/mL) 0 100 200 300 1500 2000 2500 3000 Baseline (BL) 500 pg/mL 50 pg/mL 5 pg/mL Basal Time After 120h DART Exposure 1 1E1 1E2 1 1E1 1E2 1 1E1 1E2 1 1E1 1E2 1 1E1 1E2 1 1E1 1E2 PD-L1 PD-L2 B7-H3 CD80 Mean Fluorescence Intensity CD86 CD45 Top Panel: Donor PBMCs from an AML patient containing 24% CD123-positive cells and 14.2% CD3-positive T cells were cultured in a 96-well U-bottom tissue culture plate at 6 x 104 cells/well in the presence of 500 (blue shaded histograms), 50 (orange shaded histograms), or 5 (green shaded histograms) pg/mL of MGD006 for 2 days. PD-1 and PD-L1 expression was determined on non-T cells (CD3-negative cells) or on CD3-, CD4-, or CD8-gated-T cells using flow cytometry. Untreated PBMCs (red shaded histograms) from this AML-patient were used to establish a baseline control for PD-1 and PD-L1 expression. In order to better visualize the dose response of MGD006 in upregulating PD-L1 expression in non-T cells, the red dashed line was established based on the basal level of PD-L1 expression present within the untreated group and applied across all doses of MGD006. Bottom Panel: Primary AML sample was incubated for 120 hours with 50 ng/ml of MGD006. Expression of check point inhibitors was measured at baseline and after incubation. Blue histograms represent basal levels and green post incubation. Induction of IFNγ and PD-L1 In Flotetuzumab-treated Patients Dose-dependent detection of circulating IFNγ in flotetuzumab-treated patients 300 500 300 500 0 10 20 30 40 Cohort (dose ng/kg/day) Cohort (dose ng/kg/day) IFNγ (pg/mL, mean ± SEM) 0 1 2 3 PD-L1+ AML Blasts (% of total) ■ Concurrent increase of PD-L1 expression on circulating AML blasts is noted associated with increased IFNγ in the circulation Patient samples were evaluated for circulating IFNγ levels (left panel) and PD-L1 expression on circulating AML blasts at 2 dose levels: 300 ng/kg/day and 500 ng/kg/day. PD-L1 Upregulation in Residual Bone Marrow Blasts Baseline Cycle 1 Day 25 CD274 (PD-1) CD123 10 6 10 5 10 4 10 3 10 2 10 1 10 0 10 0 10 1 10 2 10 3 10 4 10 5 10 6 98.1 78.0 21.7 0.32 0 1.46 0 0.39 10 6 10 5 10 4 10 3 10 2 10 1 10 0 10 0 10 1 10 2 10 3 10 4 10 5 10 6 CD274 (PD-L1) CD123 0 500 1000 1500 gMFI (mean ± SEM) Flow cytometry analysis of CD123 and PD-L1 in AML blast bone marrow samples pre (BL D-14) and post flotetuzumab (C1D25). Flotetuzumab Activity and PD-L1 Expression PD-L1 Expression Is Associated with Decreased Activity In Vitro and In Vivo Sample # 1 Sample # 2 Sample # 3 Sample # 4 Sample # 5 Sample # 6 80 60 40 20 CD123 CTLA4 LAG3 PD1 PDL1 PDL2 TIM3 GITR CD123 CTLA4 LAG3 PD1 PDL1 PDL2 TIM3 GITR CD123 CTLA4 LAG3 PD1 PDL1 PDL2 TIM3 GITR CD123 CTLA4 LAG3 PD1 PDL1 PDL2 TIM3 GITR CD123 CTLA4 LAG3 PD1 PDL1 PDL2 TIM3 GITR CD123 CTLA4 LAG3 PD1 PDL1 PDL2 TIM3 GITR 100 0 Expression on AML blasts (%) B. Flotetuzumab (μg/mL) 110 100 90 80 70 60 50 40 30 20 10 0 Live Cells (%) Live CD25+ T cells Live AML blasts A. 0.00001 0.0001 0.001 0.01 0.1 0.00001 0.0001 0.001 0.01 0.1 0.00001 0.0001 0.001 0.01 0.1 0.00001 0.0001 0.001 0.01 0.1 0.00001 0.0001 0.001 0.01 0.1 0.00001 0.0001 0.001 0.01 0.1 Primary AML samples were co-incubated with flotetuzumab at different concentrations for 144 hours in vitro. Figure A: Flotetuzumab induced T cell activation (cell count CD25+ T cells) in a dose dependent manner and depletion of AML blasts cells in a dose dependent manner. Figure B: Immunophenotyping of AML samples expressed as percent of total cells. Boxes highlight the expression on PD-L1 in flotetuzumab sensitive samples (green) vs resistant samples (red). [email protected]

a phase 1 study of flotetuzumab, a cd123 x cd3 dart ... · a phase 1 study of flotetuzumab, a cd123...

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