CD3 Bispecific DART Research Articles

Flotetuzumab and other T-cell immunotherapies upregulate MHC class II expression on acute myeloid leukemia cells

AbstractAcute myeloid leukemia (AML) relapse is one of the most common and significant adverse events following allogeneic hematopoietic cell transplantation (HCT). Downregulation of major histocompatibility class II (MHC-II) surface expression on AML blasts may represent a mechanism of escape from the graft-versus-malignancy effect and facilitate relapse. We hypothesized that T-cell immunotherapies targeting AML antigens would upregulate MHC-II surface expression via localized release of interferon gamma (IFN-γ), a protein known to upregulate MHC-II expression via JAK-STAT signaling. We demonstrate that flotetuzumab (FLZ), a CD123 × CD3 bispecific DART molecule, and chimeric antigen receptor expressing T cells targeting CD123, CD33, or CD371 upregulate MHC-II surface expression in vitro on a THP-1 AML cell line with intermediate MHC-II expression and 4 primary AML samples from patients relapsing after HCT with low MHC-II expression. We additionally show that FLZ upregulates MHC-II expression in a patient-derived xenograft model and in patients with relapsed or refractory AML who were treated with FLZ in a clinical trial. Finally, we report that FLZ-induced MHC-II upregulation is mediated by IFN-γ. In conclusion, we provide evidence that T-cell immunotherapies targeting relapsed AML can kill AML via both MHC-independent mechanisms and by an MHC-dependent mechanism through local release of IFN-γ and subsequent upregulation of MHC-II expression.

Combinatorial Anti-Tumor Activity in Animal Models of a Novel CD123 x CD3 Bispecific Dart® Molecule (MGD024) with Cytarabine, Venetoclax or Azacitidine Supports Combination Therapy in Acute Myeloid Leukemia

Combinatorial Anti-Tumor Activity in Animal Models of a Novel CD123 x CD3 Bispecific Dart® Molecule (MGD024) with Cytarabine, Venetoclax or Azacitidine Supports Combination Therapy in Acute Myeloid Leukemia

Preliminary Translational Results from an Ongoing Phase 1 Study of Flotetuzumab, a CD123 x CD3 Dart®, in AML/MDS: Rationale for Combining Flotetuzumab and Anti-PD-1/PD-L1 Immunotherapies

Background:Immunotherapy has transformed cancer treatment; in particular, checkpoint inhibitors (CPI) are now approved for the treatment of several solid tumors and in patients with Hodgkin's disease. In hematological malignancies, including acute myeloid leukemia (AML), the utility of CPIs may be more limited due to less mutations observed in their genomes. Immunologic treatments of hematologic malignancies targeting “shared” epitopes differentially overexpressed by hematologic cancers also represents a rational approach to the immunotherapy of AML.Methods:Translational studies were performed in an ongoing phase 1 study in patients with AML and MDS treated with flotetuzumab (MGD006/S80880), a novel CD123 x CD3 bispecific DART® protein, to assess the potential role of combining PD-1/PD-L1 inhibitors with flotetuzumab.Results:Flotetuzumab has anti-leukemic activity in patients with relapsed/refractory AML (ESMO 2017). Inherent to flotetuzumab's mode of action is redirecting T-cells to lyse AML cells in conjunction with enhancement of T-cell activation, proliferation and cytokine production. Multispectral immunohistochemistry analysis of bone marrow samples from our study showed flotetuzumab in situ with a ~2-fold increase in CD8 T-cells upon treatment; consistent with this, we observe up-regulation of PD-1 on both CD4 and CD8 T-cells along with dose dependent secretion of IFNɣ in patient samples. In line with reports of PD-L1 induction by IFNɣ, we observed PD-L1 upregulation on AML blasts incubated with IFNɣ. Furthermore, circulating levels of IFNɣ secretion in flotetuzumab-treated patients correlated with PD-L1 expression on AML blasts. Notably, primary AML samples with higher levels of PD-L1 on malignant blasts were less susceptible to flotetuzumab-mediated killing in vitro. Furthermore, patients that progressed early (within two-weeks) on flotetuzumab treatment had higher baseline levels of PD-L1 on AML cells. Interestingly, a number of patients with residual disease on flotetuzumab showed higher proportion of PD-L1 positive AML blasts vs. basal levels.Conclusions:Flotetuzumab has shown evidence of activity against CD123+ AML blasts in vivo, associated with an increase in T-cell infiltration and activation in the bone marrow, with enhanced IFNɣ secretion, which in turn may lead to upregulation of PD-1 on T cells and PD-L1 expression by the AML blasts. Synergistic cytotoxicity was observed after treatment of AML cell lines with both flotetuzumab and CPI in vitro. Furthermore, AML cells in patients that progressed on flotetuzumab or with residual disease tend to be PD-L1 positive. Taken together, these data suggest that combination with anti-PD1/PD-L1 therapy may enhance the effect of flotetuzumab in selected patients with relapsed or refractory AML. clinicaltrials.gov NCT02152956 DisclosuresFox:Bristol Myers-Squibb: Consultancy, Research Funding; AstraZeneca/MedImmune: Consultancy, Research Funding; PerkinElmer: Consultancy, Research Funding; Janssen/Johnson and Johnson: Consultancy, Research Funding; Argos: Consultancy; Bayer: Consultancy; Definiens: Consultancy; OncoSec: Consultancy, Research Funding; PrimeVax: Consultancy, Equity Ownership; Peregrine: Consultancy; UbiVac: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Co-Founder and managing Member of LLC; Ventana/Roche: Consultancy; Viralytics: Consultancy, Research Funding. Primo:Vivia Biotech: Employment. Ballesteros:Vivia Biotech: Employment. Sun:Macrogenics Inc: Employment, Equity Ownership. Lelièvre:Institut de recherches international Servier: Employment. Baughman:MacroGenics, Inc.: Employment. La Motte-Mohs:MacroGenics: Employment, Equity Ownership, Patents & Royalties; Sunnybrook Health Sciences Centre: Patents & Royalties. Muth:MacroGenics, Inc.: Employment, Equity Ownership. Moore:MacroGenics, Inc.: Employment, Equity Ownership. Bonvini:MacroGenics, Inc.: Employment, Equity Ownership, Research Funding. Wigginton:MacroGenics: Employment, Equity Ownership. Davidson-Moncada:MacroGenics: Employment, Equity Ownership.

Lead-in Dose Optimization to Mitigate Cytokine Release Syndrome in AML and MDS Patients Treated with Flotetuzumab, a CD123 x CD3 Dart® Molecule for T-Cell Redirected Therapy

Background:Flotetuzumab (MGD006/S80880) is a novel CD123 x CD3 bispecific DART® protein being tested in a Phase 1 study of patients with relapsed/refractory acute myeloid leukemia (AML) and myelodysplastic syndrome. Cytokine secretion with ensuing potential for cytokine release syndrome (CRS) is inherent in T-cell activation and is observed with T-cell redirecting therapies. Two lead-in dose (LID) strategies, in conjunction with early intervention with tocilizumab, were assessed for their ability to mitigate CRS.Methods:In LID-1 schema, flotetuzumab was administered at 100ng/kg/day(d) for 4d followed by 3d pause and resumption at 300 or 500ng/kg/d starting on Day 8. The LID-2 schema included 30ng/kg/d for 3d, 100ng/kg/d for 4d and 300 or 500ng/kg/d on Day 8. IL-2, IL-6, IL-8, IL-10, TNF-a, INF-ɣ, and GM-CSF were measured and CRS severity graded. Peak cytokine values during first reported CRS events, occurring within 10 days of start of first dose, were evaluated. Median peak cytokine levels were compared between patients with and without LID. Other potential CRS determinants were evaluated.Results:Infusion-related reactions (IRR)/CRS occurred in 34/45 (76%) of patients and were generally manageable and reversible, with most events (28/34; 82%) Grade (Gr) 1 and 2. Among 29 patients with complete cytokine data, 68% experienced CRS within 2 days of start of flotetuzumab, and an additional 8% within 10 days (14% Gr 1, 55% Gr2, and 7% Gr 3). Cytokine levels were generally higher in patients with CRS than in pts without (median IL-6, 116.2 vs. 67.9 pg/mL; IL-8, 191.1, vs. 144.6 pg/mL; IL-10, 867.6, vs. 348.7 pg/mL), and were generally higher with increasing CRS grade. LID reduced overall cytokine levels. Institution of a two-step LID in Week 1 decreased severity by mean 0.54 grade during cycle 1 (mean CRS grade week 1: 1.16 vs. 2; week 2: 1 vs. 1.33; week 3: 0.67 vs. 0.83; week 4: 0.13 vs 0.67 LID-2 vs. LID-1, respectively). Median peak cytokine levels observed with LID were lower during Week 1 and after achieving the maximum dose. Preliminary data show a relationship between baseline circulating T-cell number and maximum CRS grade during Week 1, with higher grade of CRS (≥2) in Week 1 associated with higher baseline levels of circulating T-cells. Other variables evaluated (including tumor burden) did not trend with CRS grade. Anti-leukemic activity with flotetuzumab has been reported (ESMO 2017); CRS grade and frequency did not correlate with response.Conclusions:CRS is commonly observed with T-cell-directing therapies. Two-step LID showed effectiveness in limiting IRR/CRS events and circulating cytokines over a single-step LID. Ability to predict which patients may develop CRS would be helpful when administering T-cell-activating therapies. Flotetuzumab data suggest that a patient's baseline circulating T-cell number may be a potential predictor of CRS severity. CRS severity did not correlate with anti-leukemic activity. clinicaltrials.gov NCT02152956 DisclosuresFoster:Incyte: Honoraria; Shire: Honoraria; Amgen: Honoraria; Pfizer: Research Funding; Macrogenics: Research Funding; Celgene: Research Funding; Celator: Research Funding. Uy:Boehringer Ingelheim: Consultancy; GlycoMimetics: Consultancy; Novartis: Consultancy, Other: Travel Suppport. Rizzieri:Erytech: Research Funding; Shire: Research Funding. Arellano:Cephalon Oncology: Research Funding. Topp:Amgen: Consultancy, Honoraria, Other: Travel, Research Funding; Roche: Consultancy, Research Funding; Macrogenics: Consultancy, Research Funding; Regeneron: Consultancy, Honoraria, Research Funding; Celgene: Other: Travel. Huls:Celgene: Consultancy; J&J: Consultancy. Martinelli:Amgen: Consultancy; Roche: Consultancy; Johnson&Johnson: Consultancy; Pfizer: Consultancy; Ariad/Incyte: Consultancy; Celgene: Consultancy. Ciceri:GSK: Other: B-thalassemia gene therapy was developed by Fondazione Telethon and Ospedale San Raffaele and has been inlicenced by GSK that provides funding for the clinical trial, Research Funding. Sun:Macrogenics Inc: Employment, Equity Ownership. Baughman:MacroGenics, Inc.: Employment. Shankar:MacroGenics: Employment. Lelièvre:Institut de recherches international Servier: Employment. Bonvini:MacroGenics, Inc.: Employment, Equity Ownership, Research Funding. Wigginton:MacroGenics: Employment, Equity Ownership. davidson-Moncada:MacroGenics: Employment, Equity Ownership.

Prophylactic Ruxolitinib for Cytokine Release Syndrome (CRS) in Relapse/Refractory (R/R) AML Patients Treated with Flotetuzumab

Introduction: CRS is a potentially life-threatening toxicity observed following T cell-redirecting therapies. CRS is associated with elevated cytokines, including IL6, IFNγ, TNFα, IL2 and GM-CSF. Glucocorticosteroids (GC) and the IL6 receptor blocking antibody tocilizumab (TCZ) can reduce CRS severity; however, CRS may still occur and limit the therapeutic window of novel immunotherapeutic agents. Disruption of cytokine signaling via Janus kinase (JAK) pathway interference may represent a complementary approach to blocking CRS. Ruxolitinib (RUX), an oral JAK1/2 inhibitor approved for the treatment of myelofibrosis and polycythemia vera, interferes with signaling of several cytokines, including IFNγ and IL6, via blockade of the JAK/STAT pathway. We hypothesized that RUX may reduce the frequency and severity of CRS in R/R AML patients (pts) undergoing treatment with flotetuzumab (FLZ), an investigational CD123 x CD3 bispecific DART® molecule. Methods: Relapse/refractory (including primary induction failure, early relapse and late relapse) AML pts were included in this study. RUX pts were treated at a single site, Washington University, St. Louis, MO. RUX was dosed at 10 mg or 20mg BID days -1 through 14. Comparator (non-RUX) pts (n=23) were treated at other clinical sites. FLZ was administered at 500 ng/kg/day continuously in 28-day cycles following multi-step lead-in dosing in week 1 of cycle 1. CRS was graded per Lee criteria1. Results: As of July 1st, 2020, 10 R/R AML pts, median age 65 (range 40-82) years, have been enrolled and treated in the RUX cohort (6 at 10mg, 4 at 20 mg of RUX). All pts had non-favorable risk by ELN 2017 criteria (8 adverse and 2 intermediate); 1 (10.0%) pt had secondary AML; pt characteristics in the RUX and non-RUX cohorts were balanced, except for median baseline BM blasts which was higher in non-RUX pts: 15% (range 5-72) vs (40% (range 7-84), RUX and non-RUX pts respectively. Cytokine analysis showed statistically significant (p<0.05) lower levels of IL4, IL12p70, IL13, IL15, IL17A, IFNα2, but higher levels of GM-CSF were measured in RUX vs non-RUX pts, specifically during co-administration with FLZ (Fig. 1). However, incidence and severity of CRS events were similar. In the RUX cohort, 9 (90%) pts experienced mild to moderate (grade ≤ 2; 48.6% of events were grade 1) CRS events whereas no grade ≥ 3 CRS were reported; in the non-RUX cohort, 23 (100%) pts experienced mild to moderate (grade ≤ 2; 73.1% of events were grade 1) CRS events, 1 (4.3%) grade ≥ 3 CRS was reported. Most CRS events occurred in the first 2 weeks of FLZ administration (75% and 92%, respectively). No differences in duration of CRS events were noted. However, more CRS-directed treatment was used in the RUX cohort. Five (50%) pts received a total of 12 doses of TCZ, 1 (10%) pt received GC and 1 (10%) pts received vasopressors in the RUX cohort. In the non-RUX cohort, 5 (21.7%) pts received 8 doses of TCZ, 3 (13.0%) pts received GC and 1 (3.7%) pt received vasopressors. Dose intensity (DI) at FLZ dose of 500 ng/kg/day was comparable, with median DI of 97.6% and 98.0% in RUX and non-RUX cohorts, respectively. Time to first response (TTFR; BM < 5% blasts) and time on treatment (ToT) were similar between both groups. Median TTFR was 1 cycle for both groups (range 1-2 cycles), and median ToT was 1.4 (range 0.9-5.1) and 1.8 (range 1.3-5.1) months, for RUX and non-RUX pts, respectively. Complete response rate (BM < 5% blasts) was similar: 4 (40%) in RUX pts, and 8 (34.8%) in non-RUX pts; 2 RUX (50%) and 5 non-RUX (62.5%) responders transitioned to stem cell transplant. Conclusion: Prophylactic RUX produced a clear difference in cytokine profiles but no discernable improvement in clinical CRS or response rates in FLZ treated patients. A larger study may be required to determine the prophylactic role of RUX in CRS.

Immune Senescence and Exhaustion Correlate with Response to Flotetuzumab, an Investigational CD123×CD3 Bispecific Dart® Molecule, in Acute Myeloid Leukemia

Immune Senescence and Exhaustion Correlate with Response to Flotetuzumab, an Investigational CD123×CD3 Bispecific Dart® Molecule, in Acute Myeloid Leukemia

Flotetuzumab As Salvage Therapy for Primary Induction Failure and Early Relapse Acute Myeloid Leukemia

Flotetuzumab As Salvage Therapy for Primary Induction Failure and Early Relapse Acute Myeloid Leukemia

Flotetuzumab and Other Cellular Immunotherapies Upregulate MHC Class II Expression on Acute Myeloid Leukemia Cells in Vitro and In Vivo

Background: Allogeneic hematopoietic cell transplantation (allo-HCT) is the only curative therapy for patients with high-risk and refractory acute myeloid leukemia (AML). Unfortunately, up to 50 percent of patients relapse after allo-HCT.Recent research has shown that 30-50 percent of AML samples from patients relapsing after allo-HCT have downregulation of MHC class II (MHC-II) expression, which may promote immune effector evasion and disease relapse. These studies also report that interferon gamma (IFNγ) can restore MHC-II expression. IFNγ has never been systemically administered after allo-HCT and would likely cause significant and potentially life-threatening toxicities. Reinduction of MHC-II expression may lead to re-engagement of immune effectors, restoration of the graft-versus-malignancy effect, and disease control. We hypothesized that T cell immunotherapies targeting AML cells will lead to T cell activation, localized IFNγ release, and upregulation of MHC-II on AML cells. Methods: For in vitro experiments, THP1 cells (THP1s), which have intermediate MHC-II expression, or primary human AML samples with low MHC-II expression from a patient relapsing after allo-HCT (AML-low cells) were co-cultured with or without T-cell immunotherapy and with or without human MHC-mismatched CD3+ T cells. The following T-cell immunotherapies were tested: flotetuzumab (FLZ), an investigational CD123 x CD3 bispecific DART® molecule; a CD33 x CD3 bispecific molecule (Creative Biolabs, Shirley, NY); and CD123-directed chimeric antigen receptor (CAR) T cells. THP1 IFNγ receptor-1 (IFNγR1) knockout cell lines were generated using CRISPR-Cas9. MHC-II expression was measured by flow cytometry and IFNγ concentrations via Luminex immunoflourescence assay. In order to rescue THP1s from FLZ-induced death and allow for longitudinal evaluation, a transwell plate system was used, placing THP1s, human CD3+ T cells, and FLZ in the top well and THP1s in the bottom well. This allowed for diffusion of IFNγ but not human T cells to the bottom wells, permitting MHC-II upregulation while limiting death. The upper and lower wells were coincubated together for 24 hours prior to harvesting of the THP1s in the lower well for longitudinal studies and mixed-lymphocyte reactions. For in vivo experiments, NOD-scid IL2Rgammanull mice expressing human IL-3, GM-CSF, and SCF (NSG-S) were irradiated with 250 rads and injected with 10e6 primary AML-low cells per mouse. After 5.5 weeks, mice were divided into the following groups: 1) untreated control; 2) FLZ only (2mg/kg); 3) human mismatched T cells only (10e7 T cells per mouse); 4) FLZ and T cells. Results: In vitro co-culture of THP1 or AML-low cells with FLZ and T cells led to significantly increased MHC-II expression at 48 hours when compared with the control, FLZ only, and T cell only groups (Figure 1A-B). Co-culture of THP1s with the CD123 CAR-T cells led to similar results. Although co-incubation with a CD33 x CD3 bispecific led to a similar result, the MHC-II upregulation was not nearly as dramatic as that seen with CD123 targeting agents. Using a transwell system to rescue THP1s from FLZ-mediated toxicity, FLZ-induced MHC-II upregulation on THP1s peaked at 48-72 hours (similar kinetics to what is seen with IFNγ alone). These THP1s with upregulated MHC-II activated third-party donor mismatched human CD4+ T cells to a greater extent than untreated THP1s controls. Co-cultures of THP1s with CD4+ T cells and FLZ induced the secretion of very high concentrations of IFNγ, and blockade of IFNγ signaling through knockout of IFNγR1 led to abrogation of the effect (Figure 1C-D). Finally, in an in vivo model, NSG-S mice injected with AML-low samples and treated with FLZ and T cells showed significant upregulation of MHC-II expression on the AML cells. Single cell RNA-sequencing of AML cells purified from these mice is ongoing. Conclusions: Use of FLZ and other T-cell immunotherapies targeting AML antigens led to both direct AML killing as well as significant upregulation of MHC-II expression on AML cells both in vitro and in vivo. The effect appears to be mediated primarily by IFNγ. T-cell immunotherapies represent a promising treatment approach for AML patients relapsing after allo-HCT and may lead to enhanced immune recognition in the 30-50% of patients who relapse after allo-HCT. Based on these results, a clinical trial treating patients relapsing after allo-HCT with FLZ is planned. Disclosures Christopher: Boulder Bioscience: Patents & Royalties: IP around the use of interferon gamma to treat stem cell transplant. Kim:Tmunity: Patents & Royalties: methods for gene editing in hematopoietic stem cells to enhance the therapeutic efficacy of antigen-specific immunotherapy (Licensed by University of Pennsylvania); Neoimmune Tech: Patents & Royalties: use of long-acting IL-7 analogs to enhance CAR T cells (licensed by Washington University). Muth:MacroGenics, Inc.: Current Employment, Current equity holder in publicly-traded company. Davidson:MacroGenics: Current Employment. DiPersio:Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees.

TP53 Abnormalities Correlate with Immune Infiltration and Associate with Response to Flotetuzumab Immunotherapy in Acute Myeloid Leukemia

TP53 Abnormalities Correlate with Immune Infiltration and Associate with Response to Flotetuzumab Immunotherapy in Acute Myeloid Leukemia

Improvement in Cytokine Release Syndrome Management for the Treatment of AML Patients with Flotetuzumab, a CD123 x CD3 Bispecific Dart® Molecule for T-Cell Redirected Therapy

Improvement in Cytokine Release Syndrome Management for the Treatment of AML Patients with Flotetuzumab, a CD123 x CD3 Bispecific Dart® Molecule for T-Cell Redirected Therapy

Flotetuzumab (FLZ), an Investigational CD123 x CD3 Bispecific Dart® Protein-Induced Clustering of CD3+ T Cells and CD123+ AML Cells in Bone Marrow Biopsies Is Associated with Response to Treatment in Primary Refractory AML Patients

Introduction The infiltration of immune cells into tumors has been associated with therapeutic effects in preclinical models and patients with cancer. In AML, we have previously reported that immune infiltrated TME is predictive of failure to cytotoxic chemotherapy, but associated with response to immunotherapy, specifically FLZ (Uy ASH 2018, Rutella ASH 2018). Furthermore, FLZ also affects immune infiltration in the TME (Rutella ASH 2018). NK cells play an important role in AML control (Ruggieri Science 2012). FLZ (MGD006/S80880) is a humanized DART® molecule that bridges CD123 on AML with CD3 on T cells and mediates anticancer activity via T-cell activation and cytolytic activity against the bound cancer cell. While this is well described in vitro, little evidence of this interaction is available in vivo. Methods Patients (pts) were treated on the recommended phase 2 dose (RP2D) of FLZ (multi-step lead-in dose followed by 500ng/kg/day, in 28-day cycles). We studied the bone marrow (BM) tissue samples for 6 primary refractory pts at baseline and after treatment. Response assessment was performed at day 25±3 days of each cycle. Serial BM samples were evaluated using 2 different staining panels (PD-L1, FoxP3, CD8, CD3, CD103 / CD123, CD3, CD57, CD16) on consecutive slides. Slides were stained using a Leica BondRx autostainer and fluorescence imaged using a Polaris Vectra 3 and analyzed using inForm software. A density-based clustering algorithm developed and run in QuPath was used to quantify CD3+ T cell clusters. Results Six pts with primary refractory AML were included in this report. Pts were heavily pretreated (median prior lines of therapy was 3, range 2-9), and had adverse cytogenetic risk (ELN 2017). Three pts had a complete remission (CR) after 1 cycle of therapy (CR, CRh, CRi), two went on the receive allogeneic stem cell transplant (HSCT). In baseline BM samples, CD3 and CD8 cell infiltrates were higher in CR vs non-responders (CD3+ 18.3% ±6.9 vs 9.3% ±1.8; CD8+ 9.4% ±3.5 vs 4.8% ±1.2; mean±SEM). Two of the three CR patients, who underwent HSCT, developed clusters (Figure 1) in their on-treatment biopsies with 65 and 22 clusters of an average of 34 and 17 T cells per cluster, respectively. All clusters in CR pts were found on or adjacent to CD123+ cells. The BM biopsy of the CR pt with no detected clusters had no unequivocal evidence of residual/recurrent leukemic blasts. This pt had their dose interrupted early due to non-treatment related AE (infectious complication) and did not receive a full cycle of treatment; the response was transient and the pt relapsed shortly thereafter. NK cells (CD57+CD16+) were increased in post treatment biopsies of CR vs non-responders (0.93 ±0.31 vs 0.27 ±0.13; mean±SEM) with the largest fold increase in CR (28 vs 9). Lastly, post treatment biopsy PD-L1 expression was higher in non-responders than CR (23% vs 16%) with non-responders exhibiting the largest fold change in total PD-L1+ cells (10.9 vs 2.2). Summary Consistent with its proposed mechanism of action, these data highlight for the first time, the dynamic induction of an increase in T-cell infiltration, and clustering around CD123 AML cells in the bone marrow microenvironment of two AML patients that responded to FLZ. In pts with resistance to FLZ (non-responders) PD-L1 induction was significantly higher indicating that in some pts treatment with sequential check point inhibitor could obviate this mechanism of resistance A trial combining FLZ with sequential administration of a PD-1 inhibitor (MGA012) is currently recruiting pts. Figure 1. Baseline and on-treatment IHC of BM biopsies of a FLZ-treated CR pt showing cluster formation following treatment. Disclosures Bifulco: Ventana: Other: advisory board; PrimeVax: Equity Ownership, Other: ScientificBoard; BMS: Other: Advisory Board; Providnece: Patents & Royalties: Imaging processing; Halio Dx: Other: advisory board. Wigginton:macrogenics: Employment, Equity Ownership; western oncolytics: Consultancy, Other: consultancy. Muth:MacroGenics, Inc.: Employment, Equity Ownership. Davidson-Moncada:MacroGenics, Inc.: Employment, Equity Ownership. Fox:Akoya: Research Funding; Bristol Myers Squibb: Research Funding; Definiens: Membership on an entity's Board of Directors or advisory committees; Macrogenics: Research Funding; Ultivue: Membership on an entity's Board of Directors or advisory committees.

Flotetuzumab, an Investigational CD123 x CD3 Bispecific Dart® Protein, in Salvage Therapy for Primary Refractory and Early Relapsed Acute Myeloid Leukemia (AML) Patients

Flotetuzumab, an Investigational CD123 x CD3 Bispecific Dart® Protein, in Salvage Therapy for Primary Refractory and Early Relapsed Acute Myeloid Leukemia (AML) Patients

Immune Landscapes Predict Chemotherapy Resistance and Anti-Leukemic Activity of Flotetuzumab, an Investigational CD123×CD3 Bispecific Dart® Molecule, in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Immune Landscapes Predict Chemotherapy Resistance and Anti-Leukemic Activity of Flotetuzumab, an Investigational CD123×CD3 Bispecific Dart® Molecule, in Patients with Relapsed/Refractory Acute Myeloid Leukemia

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

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 (Vergez et al 2011). 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) acute myeloid leukemia (AML). In this study, flotetuzumab led to T-cell activation which in turn was associated with PD-1 induction on T lymphocytes, enhanced IFNɣ secretion, and upregulation of PD-L1 expression by AML blasts (ASH 2018 Rutella, ASH 2018 Uy). 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, also known as INCMGA00012, is an investigational anti-PD-1 antibody that has shown clinical activity in a Phase 1 study (SITC 2018 Mehnert). 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. Methods This is a Phase 1 dose escalation study designed to characterize the safety, tolerability, dose-limiting toxicities, maximum tolerated dose (MTD) or maximum administered dose (if no MTD is defined), pharmacokinetics, and preliminary anti-leukemic activity of flotetuzumab in combination with MGA012, each administered intravenously (IV) in patients with R/R AML. Response evaluation will be determined by modified ELN 2017 criteria. Activity is measured by complete response (CR) (complete remission [CR], or CR with partial hematologic recovery [CRh], or CR with incomplete hematological recovery [CRi], or morphologic leukemia-free state [MLFS]) rate, relapse-free survival, or mortality rate at 1 and 3 months. The impact of flotetuzumab/MGA012 combination on overall survival and event-free survival will be explored. Eligible patients will consist of adults with relapsed or refractory AML (any subtype except acute promyelocytic leukemia) who have exhausted standard of care options. In Induction Cycle 1, patients will be treated with a step-up lead in dose of flotetuzumab, followed by continuous infusion flotetuzumab, starting at week 2 of Cycle 1 and continuing through each 28-day cycle. MGA012 will be administered every two weeks. Depending on response, patients will transition to either consolidation or second induction. Eligible patients who achieve CR/CRh/CRi can receive maintenance MGA012 alone for up to 12 months. Disclosures Wei: AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax, Research Funding, Speakers Bureau; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Honoraria, Research Funding; Janssen: Honoraria. Fong:Novartis: Speakers Bureau; Amgen: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Astellas: Consultancy. Montesinos:Karyopharm: Membership on an entity's Board of Directors or advisory committees, Other: Research support; Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research support, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research support, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Research support, Research Funding, Speakers Bureau. Gil:Jazz Pharmaceuticals: Honoraria; Gilead: Honoraria; Daiichi-Sankyo: Honoraria; Novartis: Honoraria, Research Funding; Pfizer: Honoraria; Abbvie: Honoraria. Perez De Oteyza:Celgene: Speakers Bureau. Rowe:BioSight: Consultancy. Wolach:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Speaker; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Speaker. Sun:MacroGenics, Inc.: Employment, Equity Ownership. Baughman:MacroGenics, Inc.: Employment, Equity Ownership. McNulty:MacroGenics, Inc.: Employment, Equity Ownership. Bonvini:MacroGenics, Inc.: Employment, Equity Ownership. Wigginton:Western Oncolytics: Other: clinical advisory board; MacroGenics, Inc.: Employment, Equity Ownership. Davidson-Moncada:MacroGenics, Inc.: Employment, Equity Ownership.

Abstract 1560: Selection of a bispecific trivalent HER2 x CD137 TRIDENT format providing optimal tumor-anchored immune co-stimulation

Abstract Introduction: CD137 (4-1BB) signaling provides co-stimulation of CD8 or NK cells following antigen or FcγR engagement, respectively. Efforts to leverage CD137 co-stimulation via agonistic monoclonal antibodies (mAbs) have been thwarted by limited clinical efficacy or unacceptable toxicity. Bispecific targeting strategies linking CD137 activation to a tumor-targeting moiety provides an approach to localize CD137 activation to the tumor microenvironment. Here we evaluate a panel of Fc-bearing HER2 x CD137 bispecific molecules incorporating different valency and geometry to define the format providing optimal CD137 co-stimulation in a tumor-cell anchor-dependent manner. Methods: An anti-HER2 mAb specificity that does not cross compete with margetuximab, trastuzumab or pertuzumab and a proprietary anti-CD137 mAb were utilized to assemble a set of HER2 x CD137 bispecific molecules in bivalent and tetravalent DART® or trivalent TRIDENTTM configurations. The resulting molecules were compared in binding, signaling and co-stimulation assays in the presence or absence of tumor cells expressing HER2. Combination studies were performed in vitro and in immune deficient mice reconstituted with human PBMCs. Results: TRIDENT molecules bearing bivalent CD137 and monovalent HER2 binding achieve optimal HER2-dependent tumor-cell anchored CD137 immune cell co-stimulation. CD137 co-stimulation increases proportionally with the level of HER2 expression as observed with HER2 1+ (MCF7 breast), HER2 2+ (JIMT1 breast) and 3+ (N87 gastric) tumor cells and was paralleled with increased HER2+/CD137+ cell association. No CD137 activation is observed in the absence of HER2-expressing tumor cells. HER2 x CD137 bispecifics enhance NK-cell proliferation and IFN-γ release induced by margetuximab, an Fc-optimized anti-HER2 mAb that up-regulates CD137 expression on NK-cells concomitant with enhanced ADCC against HER2-positive cells. Similarly, HER2 x CD137 bispecific molecules enhanced the in vitro activity of orlotamab, a B7-H3 x CD3 bispecific DART molecule that up-regulates CD137 during T-cell redirected killing. Finally, in vivo mouse studies demonstrate the ability of HER2 x CD137 molecules to expand tumor-associated CD8 cells when co-administered with a tumor targeted CD3 bispecific molecule and support enhance anti-tumor activity. Conclusion: An optimal HER2 x CD137 bispecific format providing maximal CD137 activation in a HER2- dependent manner was identified as a trivalent TRIDENT molecule bearing bivalent CD137 and monovalent HER2 binding. Combinatorial activity with HER2 x CD137 bispecifics was observed with both a HER2-directed therapeutic mAb and a CD3-engaging tumor-targeted bispecific molecule. HER2 x CD137 TRIDENT molecules have therapeutic potential and provide a structural template for incorporating alternate tumor- and/or co-stimulatory-targeting arms. Citation Format: Liqin Liu, Chia-Ying K. Lam, Ralph Alderson, Vatana Long, Yinhua Yang, Robert Burns, Lusiana Widjaja, Jonathan Li, Christina Wolf, Valentina Ciccarone, James Tamura, Gundo Diedrich, Ezio Bonvini, Syd Johnson, Paul A. Moore. Selection of a bispecific trivalent HER2 x CD137 TRIDENT format providing optimal tumor-anchored immune co-stimulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1560.

Management of Cytokine Release Syndrome in AML Patients Treated with Flotetuzumab, a CD123 x CD3 Bispecific Dart® Molecule for T-Cell Redirected Therapy

Management of Cytokine Release Syndrome in AML Patients Treated with Flotetuzumab, a CD123 x CD3 Bispecific Dart® Molecule for T-Cell Redirected Therapy

Bone Marrow T Cell Changes By Multiplex IHC after Treatment with Flotetuzumab, a CD123 x CD3 Bispecific Dart® Protein, in a Primary Refractory t-AML Patient

Therapy-related acute myelogenous leukemia (t-AML) is associated with adverse genetic lesions, complex karyotype, and TP53 mutation; it is challenging to treat and confers a poor prognosis. We describe a 74-year-old female patient with AML that developed 9 years after receiving 6 cycles of cytotoxic (FOLFOX) chemotherapy as adjuvant treatment of colorectal carcinoma. At diagnosis, the bone marrow (BM) biopsy revealed blast count of 35%, with normal karyotype, 5q loss and AML1 (RUNX1) locus (21q22) amplification by fluorescence in situ hybridization (FISH). Initial treatment with 5 cycles of azacitidine (AZA) failed to induce a response. The patient was subsequently treated on a Phase 1 trial of flotetuzumab (MGD006/S80880) (FLZ), a novel T-cell redirecting (CD123 x CD3) DART protein [NCT02152956]. Prior to FLZ, BM blasts demonstrated clonal evolution with a complex karyotype (92,XXXX, t(14;21)(q22;q22)) and new IDH1, and TET2 mutations.Patient received a total of 3 cycles (28 days/cycle) of FLZ. After one FLZ cycle, the patient achieved a (complete response) CR, with normal cytogenetics, and residual IDH1 and TET2 mutations. After 2 additional cycles of FLZ consolidation, the CR was maintained, with loss of the IDH1 mutation, but persistence of the TET2 mutation. CR was maintained with no additional therapy for approximately 7 months. Serial BM samples were evaluated for T cells (CD3, CD4, CD8, FOXP3 and PD-L1) using multiplex IHC (Fig 1). BM T cells were unchanged during AZA treatment. At the initial bone marrow on FLZ (CR), significant increases in CD3+, CD3+CD8-, CD3+ CD8+, and FOXP3-positive T cells and PD-L1 expression compared to baseline were noted. CD3+CD8+ T cells persisted in the BM 1 month beyond completion of the additional 2 cycles of consolidation with FLZ, while other T cells subsets and PD-L1 expression returned to baseline (Fig. 1) Three months after the last FLZ treatment, all T cell subsets had returned to baseline, with an early increase in leukemic blasts (8%), but normal cytogenetics. Five months after FLZ treatment blasts were unchanged, but a new abnormal cytogenetic clone, with additional mutations, accompanied by a rise in PD-L1 expression cells was observed. Seven months after FLZ treatment, frank leukemia with 50% blasts developed, and all T cell subsets and PD-L1 expression had returned to pre-treatment levels.Consistent with its proposed mechanism of action, these data highlight for the first time the induction of an increase in T-cell infiltration, which persist beyond FLZ, in the bone marrow microenvironment of an AML patient that also achieved a complete and durable anti-leukemic response after treatment with FLZ. [Display omitted] DisclosuresLelièvre:Servier: Employment. Wigginton:MacroGenics: Employment. Davidson-Moncada:MacroGenics: Employment. Fox:MacroGenics: Research Funding.

Phase 1 Cohort Expansion of Flotetuzumab, a CD123×CD3 Bispecific Dart® Protein in Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML)

Phase 1 Cohort Expansion of Flotetuzumab, a CD123×CD3 Bispecific Dart® Protein in Patients with Relapsed/Refractory Acute Myeloid Leukemia (AML)

Adaptive Immune Gene Signatures Correlate with Response to Flotetuzumab, a CD123 × CD3 Bispecific Dart® Molecule, in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Background. The therapeutic approach in patients (pts) with acute myeloid leukemia (AML) has not changed substantially in >30 years. The introduction of new treatment strategies, including immunotherapy, remains a priority. Flotetuzumab, a CD123 × CD3 bispecific DART immunotherapy, is being tested in a phase 1/2 study of relapsed/refractory (R/R) AML. We previously showed that AML pts with an immune-enriched and IFN-γ-dominant tumor microenvironment (TME) experience significantly shorter relapse-free survival, suggesting refractoriness to standard induction chemotherapy (Vadakekolathu J, et al. Blood 2017; 130: 3942A). Herein, we report that an IFN-γ-dominant TME, while predicting resistance to standard therapy, is favoring response of AML to flotetuzumab. Methods. Gene expression was analyzed in 78 bone marrow (BM) samples (36 at baseline, 27 post-cycle 1 and 15 post-cycle 2) from 40 pts with relapsed or refractory AML enrolled in a phase 1/2 clinical trial of flotetuzumab (NCT#02152956). Thirty-six baseline BM samples were included in the analysis, of which 34 from pts who were treated at the target dose of ≥500 ng/kg/day. The NanoString PanCancer IO360™ assay was used to assess the expression of 770 genes, including the levels of 14 immune cell types and of 32 immuno-oncology signatures, and their correlation with response to flotetuzumab. Data are presented as score means per group±SEM and analyzed by unpaired t-test. Results. Gene expression analysis of BM samples at baseline stratifies flotetuzumab-treated pts into 3 clusters within an immunological continuum: immune-depleted, immune-exhausted and immune-enriched (Fig. 1A). Pts with primary-refractory disease (refractory to ≥2 induction attempts, first CR of Conclusions. We provide evidence for a range of immune gene expression profiles in AML, with primary refractory pts displaying an enhanced immune infiltration signature compared with relapse pts. Furthermore, an IFN-γ-related gene signature at baseline, a feature of primary refractory pts, was associated with clinical response to flotetuzumab. HMA-refractory pts showed an immune-rich but exhausted phenotype with PD-L1 expression, suggesting these pts may further benefit from flotetuzumab combination therapy with checkpoint inhibition (Rettig M, et al. Blood 2017; 130: 1365). Lastly, treatment with flotetuzumab further shifted the immune signature toward a more immune rich phenotype. The AML TME immune gene expression can influence susceptibility to therapy, with primary refractory AML showing an IFN-γ-dominant signature associated with response to flotetuzumab. Disclosures Rutella:NanoString Technologies: Research Funding. Church:NanoString Technologies: Employment. Viboch:NanoString Technologies: Employment. Sullivan:NanoString Technologies: Employment. Hood:NanoString Technologies: Employment. Warren:NanoString Technologies: Employment. Cesano:NanoString Technologies: Employment. La Motte-Mohs:MacroGenics: Employment, Equity Ownership. Muth:MacroGenics: Employment. Lelievre:Servier: Employment. Lowenberg:Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity9s Board of Directors or advisory committees; Agios Pharmaceuticals: Membership on an entity9s Board of Directors or advisory committees; international Scientific Advisory Board, Institute Gustave Roussy, Paris: Membership on an entity9s Board of Directors or advisory committees; Clear Creek Bio Ltd: Consultancy, Honoraria; Chairman Scientific Committee and Member Executive Committee, European School of Hematology (ESH, Paris, France): Membership on an entity9s Board of Directors or advisory committees; Editorial Board "European Oncology & Haematology": Membership on an entity9s Board of Directors or advisory committees; Editorial Board "The Netherlands Journal of Medicine": Membership on an entity9s Board of Directors or advisory committees; Elected member, Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity9s Board of Directors or advisory committees; Supervisory Board, National Comprehensive Cancer Center (IKNL), Netherlands: Membership on an entity9s Board of Directors or advisory committees; Chairman, Leukemia Cooperative Trial Group HOVON (Netherlands): Membership on an entity9s Board of Directors or advisory committees; Editorial Board "International Journal of Hematology": Membership on an entity9s Board of Directors or advisory committees; "Up-to-Date", section editor leukemia: Membership on an entity9s Board of Directors or advisory committees; Astex: Consultancy; Celgene: Membership on an entity9s Board of Directors or advisory committees. Davidson-Moncada:MacroGenics: Employment.

A Next-Generation Fc-Bearing CD3-Engaging Bispecific DART® Platform with Extended Pharmacokinetic and Expanded Pharmacologic Window: Characterization As CD123 x CD3 and CD19 x CD3 DART Molecules

Background: CD3-engaging DART molecules direct T cells to tumor-expressed antigens. Flotetuzumab, a CD123 x CD3 bispecific DART molecule that targets the differential expression of the IL-3 receptor alpha chain (CD123) on acute myeloid leukemia (AML) blasts and leukemic stem cells, is currently being investigated in a phase 1 study in relapsed/refractory AML and myelodysplastic syndrome (MDS), with initial evidence of clinical activity1. A common adverse event in redirected T-cell killing interventions is cytokine release syndrome (CRS), a Cmax-associated event that may limit their therapeutic window. Owing to its short circulating half-life, flotetuzumab is administered as continuous infusion, which affords prolonged exposure with limited Cmax excursions. In contrast, long-acting Fc-bearing, CD3-engaging molecules would eliminate the need for continuous dosing, but would be especially impacted by CRS, given the high Cmax levels required to maintain adequate trough concentrations over several days or weeks. We previously reported the development of a CD3-engaging DART molecule with reduced affinity for CD3 that maintained maximal target cell killing and T-cell proliferation, albeit at higher concentrations than its wild-type (WT) counterpart, but with reduced cytokine release2. We report here further optimization and validation of the approach.Methods: Anti-CD3 variants spanning a range of affinities were formatted as Fc-bearing DART molecules with CD123- or CD19-targeting arms and evaluated for cell binding as well as for antigen-dependent induction of T-cell proliferation, cytolytic activity and cytokine release. A therapeutic index (TI) was determined from the ratio of in vitro cell killing activity to that of target cell-induced cytokine release. In vivo anti-tumor activity was assessed in human immune cell-reconstituted mouse tumor models or in mice expressing the epitope recognized by the CD3 arm of the DART proteins (human CD3 k/i mice). Safety, pharmacokinetic (PK) and biological activity of selected molecules was evaluated in cynomolgus monkeys.Results: Six Fc-bearing DART molecules (from a panel of 23 CD123 x CD3 DART variants) were selected for characterization. These molecules spanned a relatively small interval of low CD3 affinities, but varied greatly in activity, from inactive at all concentrations tested to being capable of lysing tumor cells, including primary leukemic and MDS blasts, to the same maximal level of killing observed with the parental WT DART molecule. Higher concentrations of the active variants were needed, owing to a deliberate design incorporating decreased CD3 binding. At levels capable of complete tumor cell lysis, active DART variants showed greatly reduced pro-inflammatory cytokine release (e.g., IL-2, IFN-γ and TNF-α) in vitro and in human PBMC-reconstituted mice compared to the WT version. Molecules were ranked based on their TI and a version with a highly favorable index was engineered as a B-cell targeting CD19 x CD3 DART molecule to conveniently ascertain its biological activity in cynomolgus monkeys. The CD19 x CD3 DART variant demonstrated good tolerability at single doses up to 30 mg/kg. B-cell depletion in the circulation and lymphoid tissues occurred at 1 mg/kg and achieved maximal depletion at ≥10 mg/kg, equivalent to the degree of reduction observed with 0.1 mg/kg of the WT molecule. However, only minimal circulating pro-inflammatory cytokines (including IL-6) were observed at all doses of the DART variant, while a substantial increase in IL-2, IL-6 and IFN-γ (among others) was observed with 0.1 mg/kg of the WT counterpart. The PK profile of the DART variant in cynomolgus monkeys appeared linear in the 1-30 mg/kg interval, with a half-life of 5 to 10 days, consistent with possible clinical dosing at weekly or longer intervals.Conclusions: A next-generation CD3-engaging Fc-bearing DART platform was generated through CD3 arm affinity modulation. These DART variants feature extended PK and an expanded TI suitable for potential clinical development in hematological malignancies.1. Uy et al, Blood 2017, vol. 130, Suppl 1 6372. Huang et al, Keystone Symposia: Antibodies as Drugs, 2/25-3/1/2018, Whistler, BC, Canada DisclosuresBonvini:MacroGenics: Employment, Equity Ownership. La Motte-Mohs:MacroGenics: Employment, Equity Ownership. Huang:MacroGenics, Inc.: Employment, Equity Ownership. Lam:MacroGenics, Inc.: Employment, Equity Ownership. Kaufman:MacroGenics, Inc.: Employment, Equity Ownership. Liu:MacroGenics, Inc.: Employment, Equity Ownership. Alderson:MacroGenics, Inc.: Employment, Equity Ownership. Stahl:MacroGenics, Inc.: Employment, Equity Ownership. Brown:MacroGenics, Inc.: Employment, Equity Ownership. Li:MacroGenics, Inc.: Employment, Equity Ownership. Sharma:MacroGenics, Inc.: Employment, Equity Ownership. Tamura:MacroGenics, Inc.: Employment, Equity Ownership. Johnson:MacroGenics, Inc.: Consultancy, Equity Ownership. Moore:MacroGenics, Inc.: Employment, Equity Ownership.