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LIST OF TABLES Table 1: Abbreviations and Specialist Terms .............................................................................6
Table 2: Test Articles Used in Study ALPN100-PHRM-001 .....................................................9
Table 3: Test Materials Used in Study ALPN100-PHRM-001 ..................................................9
Table 4: Analysis Tools Used in Study ALPN100-PHRM-001 ...............................................11
Table 5: ALPN-101 Binding Affinity (EC50) to CD28, ICOS, and CTLA-4 Across Species Assessed by Flow Cytometric Analysis ........................................................16
Table 6: ALPN-101 Demonstrates Superior Binding to CD28 Compared to that of WT ICOSL-Fc1.1 .......................................................................................................17
Table 7: ALPN-101 KD, ka, kd, Errors, and Full R2 Measured by BLI Analysis.....................18
Table 8: ALPN-101 Flow Cytometric Raw Binding Values (MFI): Human Counter Structures ....................................................................................................................25
Table 9: ALPN-101 Flow Cytometric Raw Binding Values (MFI): Cynomolgus Counter Structures ....................................................................................................................26
Table 10: ALPN-101 Flow Cytometric Raw Binding Values (MFI): Rat Counter Structures ....................................................................................................................27
Table 11: ALPN-101 Flow Cytometric Raw Binding Values (MFI): Mouse Counter Structures ....................................................................................................................28
Table 12: ALPN-101 Flow Cytometric Raw Binding Values (MFI): Mock Transfectants ...............................................................................................................29
Table 13: ALPN-101 BLI Binding Responses for Each Replicate in the Titrations ..................30
Pharmacology Study Report Alpine Immune Sciences, Inc. ALPN100-PHRM-001
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LIST OF FIGURES Figure 1: Flow Cytometric Analysis Gating Strategy (A) and Representative Histograms of ALPN-101 Binding to Human Counter Structures (B) .......................14
Figure 2: ALPN-101 Binding to Human, Cynomolgus Monkey, Rat, and Mouse CD28, ICOS, and CTLA-4 .........................................................................................15
Figure 3: General Description of Binding Sensorgrams ............................................................19
Figure 4: CD28 Binding Sensorgram .........................................................................................19
Figure 5: ICOS Binding Sensorgram .........................................................................................20
Figure 6: CTLA-4 Binding Sensorgram .....................................................................................20
Pharmacology Study Report Alpine Immune Sciences, Inc. ALPN100-PHRM-001
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2. LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS
Table 1: Abbreviations and Specialist Terms
Abbreviation or specialist term Explanation
AIS Alpine Immune Sciences, Inc.
ALPN-101 ICOSL vIgD 236 IgV (DG44)-Fc1.1 or ICOSL vIgD-Fc1.1
ADCC Antibody-dependent cellular cytotoxicity
BLI Bio-Layer Interferometry (e.g. using the Forté Bio™ Octet system)
BSA Bovine serum albumin
CD28 Cluster of Differentiation 28
CDC Complement-dependent cytotoxicity
CTLA-4 Cytotoxic T lymphocyte-associated antigen 4
EC50 Half maximal effective concentration
Expi239FTM Subline of HEK 293, human embryonic kidney cell line
EDTA Ethylenediaminetetraacetic acid
Fc Fragment crystallizable region of immunoglobulin
Fc1.1 Fragment crystallizable region of human immunoglobulin IgG1, engineered to lack binding to Fc receptors or complement ("effectorless")
FSC Forward scatter
GLP Good Laboratory Practice
ICOS Inducible T cell costimulator
ICOSL Inducible T cell costimulator ligand
IgV Immunoglobulin-like variable domain
KBI KBI Biopharma (contract manufacturing site)
KD Equilibrium dissociation constant (= kd/ka)
kd Disassociation constant, off-rate constant
ka Association constant, on-rate constant
MFI Mean fluorescence intensity
min Minute(s)
NaN3 Sodium azide
SSC Side scatter
Pharmacology Study Report Alpine Immune Sciences, Inc. ALPN100-PHRM-001
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3. ABSTRACT
ALPN-101 [ICOSL vIgD 236 IgV (DG44)-Fc1.1] is an Fc fusion protein of a human inducible T cell costimulator ligand (ICOSL) variant immunoglobulin domain (vIgD™) designed to inhibit simultaneously the CD28 and ICOS T cell costimulatory pathways (ALPN100-CMC-002). This study determined binding by flow cytometry of ALPN-1...
ALPN-101 bound human CD28, ICOS, and CTLA-4 in flow cytometric assays with EC50s of 648, 633, and 680 pM, respectively. ALPN-101 bound cynomolgus monkey homologs of its target molecules with affinities (440, 579, 704 pM) similar to those for the human targets, and ALPN-101 bound rat (1064, 1028, 793 pM) and mouse (1153...
As assessed by the ForteBio Octet system, ALPN-101 bound recombinant soluble human CD28, ICOS, and CTLA-4 with KD values of 192, 707, and 241 pM, respectively.
Pharmacology Study Report Alpine Immune Sciences, Inc. ALPN100-PHRM-001
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4. STUDY RATIONALE AND OBJECTIVES
ALPN-101 is an Fc fusion protein containing a variable immunoglobulin domain (vIgDTM) of ICOSL engineered to have increased affinity for both ICOS and CD28, designed to provide dual inhibition costimulatory signaling (ALPN100-CMC-002).
ALPN-101 is designed to bind counter-structures ICOSL, CD28 and CTLA4. The objective of this study was to determine binding activity of ALPN-101 to its counter-structures:
1. By flow cytometric analysis of ALPN-101 binding to cells transduced and expressing CD28, CTLA-4, and ICOS based on sequences derived from species relevant for preclinical and clinical development: human (Homo sapiens), cynomolgus monkey (Macaca fascicularis), rat (Rattus norvegicus), and mouse (Mus musculus) (Rixon,...
2. Via BLI analysis using the Forté Bio™ Octet system to determine affinity (KD) of ALPN-101 for human recombinant CD28, CTLA-4, and ICOS.
Pharmacology Study Report Alpine Immune Sciences, Inc. ALPN100-PHRM-001
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5. STUDY MATERIALS
5.1. Test Articles
The test articles used in Study ALPN100-PHRM-001 are listed in Table 2.
Table 2: Test Articles Used in Study ALPN100-PHRM-001
Item Source Catalog/Lot No.
ALPN-101 [ICOSL vIgD 236 IgV (DG44)-Fc1.1] or ICOSL vIgD-Fc1.1 KBI Biopharma, Inc. Lot# 622 p23A (used for flow cytometry analyses)
ALPN-101 [ICOSL vIgD 236 IgV (DG44)-Fc1.1] or ICOSL vIgD-Fc1.1 KBI Biopharma, Inc. Lot# PDB00242 (used for BLI analyses)
WT ICOSL-Fc1.1 [WT ICOSL ECD-Fc1.1] AIS N10229
Fc1.1 control (see ALPN100-CMC-001) AIS N10118.3
ZLZ (ICOS WT ECD) FLAG His AIS P1011
ZLZ (CD28 WT ECD) FLAG His AIS P1012
(CTLA4 WT ECD) GSS His6 AIS A145
5.2. Test Materials
The test materials used in Study ALPN100-PHRM-001 are listed in Table 3.
Table 3: Test Materials Used in Study ALPN100-PHRM-001
Item Source Catalog/Lot No.
Expi293F™ Cells Gibco A14527
Expifectamine 293 transfection kit Gibco A14524
Expi293 expression media Gibco A14351-01
Opti-MEM Gibco 31985-010
PBS Gibco 14190-136
Poloxamer 188/Pluronic Acid Corning 13-901-Cl
24 well plates Thomson Instrument Co. 931568
R-Phycoerythrin AffiniPure F(ab') Fragment Goat Anti-Human IgG, Fc Fragment Specific Jackson ImmunoResearch 109-116-098
pcDNA3.1 Plasmid Expression Vector ThermoFisher Sciences V79020
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Table 3: Test Materials Used in Study ALPN100-PHRM-001 (Continued)
Item Source Catalog/Lot No.
PAIS47_CD28 (HUMAN) AIS N/A
PAIS195_ICOS_CD4_TM (HUMAN) AIS N/A
PAIS50_CTLA4 (HUMAN) AIS N/A