regulatory t cell selective il-2-fc fusion proteins for
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Regulatory T cell selective IL-2-Fc fusion proteins for the treatment of autoimmune diseases
Regulatory T cells (Tregs) are CD4+FoxP3+ cells expressing CD25 (IL-2R) that maintain immune tolerance in tissues by suppressing the function of both CD4 and CD8 effector T cells.
Tregs are dysfunctional in most autoimmune diseases, and a promising therapeutic approach has been to restore their numbers and function. One such approach has been a low-dose IL-2 regimen since Treg homeostasis depends on IL-2. However, IL-2 as a drug suffers from fast in vivo clearance and a narrow therapeutic index.
To solve this problem we generated a long-lasting IL-2-Fc fusion protein with greater selectivity for Tregs: To increase selectivity for Tregs, we weakened the interaction of IL-2-Fc with CD122 (IL-2R) and/or
strengthened the interaction with CD25. We improved half-life by engineering IL-2-Fc so that it has reduced potency on Tregs. Further half-life extension was achieved by using Xencor's Xtend® Fc domain to increase FcRn binding
to identify our lead molecule XmAb®27564.
Introduction
Contact: [email protected] © 2018 Xencor, Inc., Monrovia, CA 91016 USA
XmAb27564 is well-tolerated in cynomolgus monkeys
Treg selective IL-2-Fc are engineered using Xencor’s Fc domains XmAb27564 promotes the selective and sustained expansion of Tregs in cynomolgus monkeys
XmAb27564 is a Treg selective IL-2-Fc protein that has been produced using Xencor’s heterodimer and Xtend Fc domains.
XmAb27564:- selectively leads to STAT5 phosphorylation in human and mouse Tregs in vitro- has an extended in vivo half-life due to its low potency on Tregs and Xtend Fc domain- is well tolerated in single and multiple doses administered to cynomolgus monkeys- selectively promotes a profound and sustained proliferation of Tregs in monkeys
XmAb27564 is equally selective and potent for Tregs in mice making it suitable for preclinical mouse models of autoimmune diseases.
XmAb27564 is likely to improve the therapeutic index for autoimmune indications, where low dose IL-2 therapy has demonstrated promising results and therefore its clinical development is warranted.
Monovalent IL-2-FcAnalytical SEC of purified IL-2-Fc
Conclusion
Rajat Varma, Ke Liu, Kendra Avery, Rumana Rashid, Suzanne Schubbert, Irene Leung, Christine Bonzon, Liz Bogaert, John Desjarlais and Matthew Bernett
Fc HeterodimerXtend
Engineered IL-2-Fc selectively promotes Treg signaling in humans and mice
XmAb27564 preserves suppression of rapamycin-expanded human Tregs
Tregs were cultured in RPMI media containing 10% FBS, 0.5 g/mL anti‐CD28, 100 ng/mL rapamycin and either 10 µg/mL XmAb27564 or 10 ng/mL recombinant human IL‐2 for 15 days prior to seeding suppression assay.
Suppression assay seeded with 1 x 105 CFSE labeled human PBMCs and indicated numbers of Tag-it Violet labeled Tregs on plate-bound anti-CD3 (OKT3; 100 ng/mL).
XmAb27564 exhibits enhanced pharmacokinetics in cynomolgus monkeys
IL‐2 IL‐2 IL‐2 IL‐2
WT IL‐2
Affinity Low(~10 nM) Medium (~100 pM) High (~10 pM) Medium (~1 nM)
Signaling ‐ ‐ ++++ ++
XmAb27564
Affinity Low Medium High Very low
Signaling ‐ ‐ +++ ‐
Load
IL2‐Fc HeterodimerEmpty‐Fc Homodimer
pSTA
T5 M
FI
10-1 100 101 102 103 104 105 106 1070
2000
4000
6000
8000
XENP26109*
Concentration (pM)
pSTA
T5 M
FI
CD8+ CD44 highCD4+ CD44 highTregs
IL-2 signaling in human T cells IL-2 signaling in mouse T cells
%Pr
olife
ratin
g ce
lls
Sustained pharmacokinetics up to several days in cynomolgus monkeys
CD
4+C
D45
RA
-(F
old
base
line)
CD
8+C
D45
A-
(Fol
d ba
selin
e)
CD
16+
NK
Cel
ls(F
old
base
line)
Treg
s(F
old
base
line)
Tregs CD4 Memory Cells
CD8 Memory Cells NK Cells
CD
4+ C
D45
RA
-(F
old
base
line)
CD
8+ C
D45
RA
-(F
old
base
line)
CD
16+
NK
cel
ls(F
old
base
line)
Albu
min
(Fol
d ba
selin
e)
Sodi
um(F
old
base
line)
Chl
orid
e(F
old
base
line)
Treg expansion in response to repeat dosing of XmAb27564 on day 0 and day 15 in cynomolgus monkeys
Tregs CD4 Memory Cells
CD8 Memory Cells NK Cells
Eosi
noph
ils(F
old
base
line)
Albu
min
(Fol
d ba
selin
e)
Eosi
noph
ils(F
old
base
line)
Bas
ophi
ls(F
old
base
line)
Serum albumin as a measure of vascular leakage
Sodium Chloride
Eosinophils Basophils
Repeat dosing of XmAb27564 is well tolerated in cynomolgus monkeys
Albumin
Eosinophils Basophils
%Pr
olife
ratin
g ce
lls
pSTA
T5 M
FI
pSTA
T5 M
FI
* XENP26109 is the non-Xtend version of XmAb27564