Immunodepletion of MDSC by AMV564, a Novel Tetravalent Bispecific - - PowerPoint PPT Presentation

Immunodepletion of MDSC by AMV564, a Novel Tetravalent Bispecific CD33/CD3 T-Cell Engager, Restores Immune Homeostasis in MDS In Vitro

Pingyan Cheng1, Erika A. Eksioglu1, Xianghong Chen1, Max Wei1, Jeanmarie Guenot2, Judith A. Fox2, Alan List1 and Sheng Wei1.

1Immunology and Malignant Hematology Program, H. Lee

Moffitt Cancer Center & Research Institute, Tampa, FL;

2Amphivena Therapeutics, San Francisco, CA

Abstract 51

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Disclosures

• J. Guenot: Amphivena Therapeutics, Inc: Employment
• J.A. Fox: Amphivena Therapeutics, Inc: Consultancy
• Sheng Wei: scientific advisor for Amphivena Therapeutics, Inc
• Alan List: medical & scientific advisor for Amphivena

Therapeutics, Inc

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T Cell MDSC

↑ROS ↑RNS ↑NO ↓L-arginine ↓L-cysteine Tregexpansion

IFN-γ, interferon-gamma; RNS, reactive nitrogen species; ROS, reactive oxygen species; TCR, T cell receptor

Tumor Microenvironment

Altered TCR-function ↓Proliferation ↑Apoptosis ↓IFN-γ production

MDSC Are Key Innate Immune Effectors in MDS Pathogenesis

• Immature CD33+ myeloid cells with distinct function & phenotype

‐ Induce tumor immune tolerance and regulatory T-cell expansion ‐ Suppress autologous hematopoiesis ‐ Suppress T-cell proliferation and IFN-γ production ‐ S100A9 is an autocrine driver of MDSC expansion and paracrine inducer of pyroptosis in autologous hematopoietic progenitors

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MDSC Express High Density CD33 & are Increased in MDS Bone Marrows

Chen X et al. J Clin Invest. 2013; 123:4595-4611.

MDSC CD33 Surface Density

P<0.0001

• MDSCs are distinguished phenotypically by CD33high and

HLA-DR−Lin−

• Genetically distinct and not derived from the mutant clone

% BM Lin-/CD33Hi MDSC

P<0.0005

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Cell Death

P<0.001

MDSC Depletion & Add-Back Granzyme B Polarization

MDSC are Key Effectors of Progenitor Cell Death & Ineffective Hematopoiesis

Chen X et al. J Clin Invest. 2013; 123:4595-4611.

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AMV564 is a Highly Potent CD33xCD3 T- Cell Engager Targeting CD33Hi Cells

AMV564

• AMV564 is a bispecific,

bivalent, 2X2 T-cell engager ‐ Composed of human antibody variable fragments (scFv) ‐ Two recognition sites for both CD33 & CD3 with strong avidity ‐ Results in T-cell directed lysis of CD33 myeloid cells

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Methods

Primary BM mononuclear cells (BMMNC) from15 MDS patients AMV564 (± α- PD1) or isotype IgG (control) 5-7 days in vitro Stem cells:

• DNA damage

(gH2AX)

• CFC

T cells:

• Percent reduction
• Proliferation

(BrdU/CellTrackerTM)

• Function (IFN-γ)

MDSC:

• percent reduction

BrdU, bromodeoxyuridine; gH2AX, phosphorylated histone 2AX; IFN-γ, interferon-gamma, CFC, colony-forming capacity; AMV564 50ng/ml, α-PD1 10 ug/ml

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AMV564 Treatment Depletes CD33Hi MDSC in BMMNC from MDS Patients

Media IgG (control) AMV564

P ≤ 0.001

IgG AMV564

BMMNC, bone marrow mononuclear cells, 7 day incubation

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Control

CD4 IFN-g CD4 Brdu

AMV564 Treatment Activates CD4+ T-cells in MDS BMMNC

Media AMV564

10 CD8 IFN-g Brdu CD8

AMV564 Treatment Activates CD8+ T-cells in MDS BMMNC Samples

Control Media AMV564

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Dose-dependent Depletion of MDSC by AMV564 Induces Proportionate T-Cell Activation

P ro p o rtio n 1 2 3 1 0 2 0 3 0 4 0 5 0

M D S C

P ro p o r tio n o f C e lls

Ig G (C o n tro l) A M V 564 0.1 µg /m l A M V 564 0.2 µg /m l A M V 564 0.5 µg /m l

MDSC

P ro p o rtio n P ro life ra tio n (B rd U ) F u n c tio n (IF N -g a m m a ) 2 0 4 0 6 0

C D 4 + T c e lls

P ro p o rtio n o f C e lls

CD4+ T cells

P ro p o rtio n P ro life ra tio n (B rd U ) F u n c tio n (IF N -g a m m a ) 2 0 4 0 6 0 8 0

C D 8 + T c e lls

P ro p o rtio n o f C e lls

CD8+ T cells

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AMV564 Depletion of MDSC Improves CFC & Decreases DNA Damage

IgG (control) AMV564 IgG AMV564

P ≤ 0.01 [n=6]

CFU-GEMM Formation DNA Damage (gH2AX)

4.98 1.35

gH2AX, phosphorylated histone 2AX CD34 gH2AX

5 10 15 20 25 30 35

IgG AMV546 Colonies (1x105 MDS BM cells)

P=0.018

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AMV564 Depletion of MDSC Enhances CD8 T-cell Response to PD-1 Blockade

IFN-γ

α-PD1 AMV564 + α-PD1 IgG AMV564

BrdU

BrdU, bromodeoxyuridine; IFN-γ, interferon-gamma; PD-1, programmed cell death protein 1

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IFN-γ

α-PD1 AMV564 + α-PD1 IgG AMV564

BrdU

BrdU, bromodeoxyuridine; IFN-γ, interferon-gamma; PD-1, programmed cell death protein 1

AMV564 Depletion of MDSC Enhances CD4 T-cell Response to PD-1 Blockade

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In Vivo Proof of Principal Case from AMV564 Phase I AML Trial

• Medical History

‐ 85 years/male ‐ Secondary AML (AML with MDS-related changes) ‐ Complex karyotype ‐ Resistant to HMA therapy

• Baseline characteristics

‐ Low disease burden (5% blasts at baseline) ‐ Low blood counts ▪ Neutrophils: 0.5 x 109/L (500/μL) ▪ Hemoglobin: 8.3 g/dL (transfusion-dependent) ‐ High inflammatory state ▪ CRP: 93 mg/L

CRP, C-reactive protein; FIH, first-in-human; HMA, hypomethylating agent

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Patient 004: Blood count changes from baseline

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• AMV564 effectively depletes CD33Hi MDSCs in a dose-

dependent fashion

• AMV564 restores immune homeostasis

‐ proliferation of CD4+ and CD8+ T-cells more than doubled with AMV564 treatment ‐ IFN-γ secretion markedly increased in AMV564-treated cells

• Suppression of MDSCs by AMV564 reduced DNA damage

in CD34+ cells and improved colony-forming capacity

• AMV564 depletion of MDSC enhances CD4/CD8 T-cell

response to PD-1 blockade and warrants investigation in lower risk MDS

Conclusions

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Acknowledgements

Wei Lab

• Pingyan Cheng
• Erika Eksioglu
• Xianghong Chen
• Alexis Burnette

Collaborators

• Alan List
• Eric J. Feldman
• Tae H. Han
• John F. DiPersio
• Peter Westervelt
• Michael Rettig