Simultaneous checkpoint-checkpoint or checkpoint-costimulatory receptor targeting with bispecific antibodies promotes enhanced human T cell activation Michael Hedvat, Christine Bonzon, Matthew Bernett, Gregory L. Moore, Kendra Avery, Rumana Rashid, Alex Nisthal, Suzanne Schubbert, Rajat Varma, Sung-Hyung Lee, Liz Bogaert, Irene W.L. Leung, Seung Chu, Umesh Muchhal and John R. Desjarlais
Dual Checkpoint Blockade
100 80 60 40 20 0 0
1
2
3
40%
8%
46% LAG3
XmAb20717 [Log µg/mL]
XmAb20717 enhances in vivo human T cell activation similarly to combination therapy
Periphery Tumor Environment • Weak monovalent interactions • Strong bivalent interactions • No activation • TIL activation
n.s.
**
2nd checkpoint only
Vehicle αPD1
10 2
** Vehicle αPD1
10 5 2.6x
10 5
10 4
** 6.2x
** p < 0.01
2.6x
XENP αPD1 20053 + αCTLA4
10 3
XENP αPD1 20053 + αCTLA4
Vehicle αPD1
XmAb20717 analog without half-life extension (Xtend) mutations
log CTLA4 mRNA
log PD1 mRNA
Bladder Breast
4
0
1
2
3
log CTLA4 mRNA
4
Kidney
Pancreatic
Colon
Lung Squamous
Lung-Adeno
Prostate
Head & Neck
Ovarian
TCGA Research Network
Contact:
[email protected]
0
1
2
3
log PD1 mRNA Melanoma
4
10 9
** p < 0.01
10 8
** 10 7
** p < 0.01
XmAb XmAb 22841 22841 + αPD1
**
**
11.3x
3.4x
**
** ** **
Days post huPBMC/Dose #1
no huPBMC
huPBMC + XmAb20717
**
10 8
10 7
10 6
-2 0 2 4 6 8 10 12 14 16 18 20 22
10 2
10 1
Day 22 post huPBMC engraftment
5
0
αPD1 PD1 PD1 x x ICOS (A)
PD1 x (B)
** p < 0.01
2.9x
PD1 x (C)
αPD1
αPD1 + αICOS
XmAb 23104
XmAb23104 enhances human T cell activation and proliferation in vivo
10 4
NSG mice engrafted with human PBMC n.s.
800
17x
** 2.0x 10 2
700
huPBMC + vehicle huPBMC + αPD1
** p < 0.01 vs. αPD1
** p < 0.01
Vehicle αPD1 XmAb XmAb 22841 22841 + αPD1
huPBMC + XmAb22841 huPBMC + XmAb22841 + αPD1
800
600
600
500 400
400
300 200
αPD1
αPD1 + XmAb 22841
200
**
100 0 0
4
8
12
16
20
** ** ** 24
28
Days post huPBMC/Dose #1
** 32
** 10 4
10 3
NSG engrafted with human PBMC and subcutaneously engrafted with MCF7 cells
huPBMC + vehicle
**
10
10 0
NSG mice engrafted with human PBMC and KG1a-luciferase cells
Mean Tumor Volume (mm3)
3
4 3 2 1 0 -1 -1
Tumor Burden
2
log ICOS mRNA
1
log LAG3 mRNA
0
5 4 3 2 1 0 -1 -1
10 9
3
XmAb20717 enhances allogeneic anti-tumor activity no huPBMC
TILs co-express multiple checkpoints: PD1 & CTLA4, CTLA4 & LAG3, and PD1 & ICOS
2
XmAb22841 enhances allogeneic anti-tumor activity and combines productively with PD1 blockade
Tumor Burden
XmAb
1
XmAb22841 [Log µg/mL]
10 6
10 3
** p < 0.01
2.7x
0
50 40 30 20 10 0
Mixed lymphocyte reactions (multiple human donor pairs)
PD1 x Costim. Prototypes CD45+ (Counts)
IFNγ [pg/mL]
CD45+ (Counts)
10 3
LAG3-
n.s.
22x
10 4
LAG3+ 50 40 30 20 10 0 -3 -2 -1
NSG mice engrafted with human PBMC
**
27x
SEB-stimulated human PBMC (multiple healthy donors)
CTLA4-
Triple checkpoint blockade significantly enhances in vivo human T cell activation
NSG mice engrafted with human PBMC
**
XmAb22841 4%
CTLA4+
XmAb23104
PD1 x ICOS bispecific antibodies were identified in empirical screens for synergistic activities
0
Day 32 post huPBMC engraftment
10 5
IFNγ [pg/mL]
PD1+ CTLA4+ (% )
PD1
82%
100 80 60 40 20 0 -3 -2 -1
Negative control
PD1- CTLA4- (%)
2%
89%
TIL-specific targeting with XmAb bispecifics
4 3 2 1 0 -1 -1
XmAb22841
LAG3- CTLA4- (%)
XmAb20717
PD1CTLA4-
PD1
Xtend
Receptor occupancy of 293T cells co-expressing CTLA4 and LAG3
CTLA4
XmAb
CTLA4
Receptor occupancy of 293T cells co-expressing PD1 and CTLA4 PD1+ CTLA4+
αICOS Fab
IFNγ (Fold-change)
Xtend
XmAb22841 selectively binds LAG3/CTLA4 dual-positive cells
• IND filings for these bispecific antibodies are anticipated in 2018.
Dual-checkpoint positive TILs
LAG3
XmAb20717 selectively binds PD1/CTLA4 dual-positive cells
1%
1st checkpoint only
αPD1 scFv
ICOS
XmAb20717
Xtend
Negative control
• Compelling ex vivo and in vivo data support the clinical development of XmAb20717, XmAb23104 and XmAb22841.
αLAG3 Fab
IL2 (Fold-change)
CTLA4
Summary • TIL-targeting XmAb bispecifics promote T cell activation and proliferation in preclinical models.
αCTLA4 scFv
PD1
XmAb23104
CD45+ (Counts)
αCTLA4 Fab
LAG3+ CTLA4+ (%)
• Targeting of multiple immune targets with such bispecific antibodies can potentially improve the therapeutic index of combination immunotherapies and reduce treatment-associated costs.
αPD1 scFv
Checkpoint Blockade + T Cell Costimulation
nivolumab pembrolizumab
PD1
IFNγ [pg/mL]
• XmAb bispecifics combine dual-targeting of PD1 and CTLA4 (XmAb20717), CTLA4 and LAG3 (XmAb22841), and PD1 and ICOS (XmAb23104) in a single antibody to achieve TIL-specific immune activation.
XmAb22841
XmAb20717
CTLA4
• Tumor infiltrating lymphocytes (TILs) express multiple immune checkpoints and costimulatory receptors (Matsuzaki et al PNAS 2010, Fourcade et al Cancer Res 2012, Gros et al JCI 2014).
Triple Checkpoint Blockade
10 4
** p < 0.01
10 3
αPD1
Vehicle
**
*
11.3x
1.7x
10 3
10 2
XmAb 23104
** p < 0.01 * p < 0.03 Vehicle
αPD1
XmAb 23104
XmAb23104 enhances allogeneic anti-tumor activity NSG mice engrafted with human PBMC and subcutaneously engrafted with MDA-MB-231 cells
Mean Tumor Volume (mm3)
Introduction
no huPBMC 1000 800
huPBMC + vehicle 1400
** p < 0.01 * p < 0.02
huPBMC + XmAb23104
**
1200 1000
600
800
400
600 400
200
* ** ** ** ** **
0
200 0
0
4
8
12
16
20
24
28
32
Day 33 post huPBMC engraftment
Days post huPBMC/Dose #1
© 2018 Xencor, Inc., Monrovia, CA 91016 USA
