Optimized IL-6 Blockade for the Treatment of Diabetic Macular Edema

Optimized IL-6 Blockade for the Treatment of Diabetic Macular Edema
Poster #B0200
Schmidt, Michael; Tisdale, Alison; Lowden, Patricia; Kovalchin, Joseph; Furfine, Eric
Eleven Biotherapeutics, Cambridge, MA, United States.
ABSTRACT
EBI-029 ENGINEERING AND PRECLINICAL DATA
Purpose: IL-6 is a pleiotropic cytokine with established roles in inflammation and angiogenesis. Vitreal IL-6 levels are significantly elevated in patients with
diabetic macular edema and are positively correlated with both disease severity and resistance to therapeutic VEGF blockade. Here we test the hypothesis that
intravitreal administration of a rodent specific IL-6 antagonist can reduce choroidal neovascularization in a rat model and report development of EBI-029, a
novel antagonistic IL-6 antibody optimized for ocular administration.
Methods: Choroidal neovascularization (CNV) studies were performed in rats. Six animals per treatment group underwent bilateral laser treatment on Day 0
to produce three lesions per eye. On Days 3 and 10, 3 µg of a polyclonal anti-rat-IL-6 antibody was administered to the test group by intravitreal (IVT) injection
while PBS or an anti-VEGF polyclonal antibody was administered to the vehicle and positive control groups, respectively. Retinal angiography was performed
on Day 15 and 22 to measure the lesion area. EBI-029 was created by immunizing mice with recombinant human IL-6, then humanizing the resulting mouse
monoclonal through CDR grafting and affinity maturation using yeast display. Antagonistic potency was assessed using a HEK-BlueTM IL-6 reporter cell line
(Invivogen) with either IL-6 alone (cis- signaling) or IL-6 complexed with a soluble IL-6 receptor (trans-signaling).
CONCLUSIONS
EBI-029
EBI-029 Binds Site 2 of IL-6
EBI-029 is a proprietary, optimized anti-IL6 antibody that
potently blocks Site 2 of the ligand
• EBI-029 blocks Site 2 of IL-6 at the interface between gp130 and
the IL-6/IL-6Rα complex
• Site 2 epitope is accessible in both free and receptor bound IL-6
EBI-029 generation and characterization
• Immunized mice with recombinant human IL-6 and
selected clones with potent blockade of IL-6 and the
IL-6/sIL-6Rα complex
Results: In the rat CNV model, IVT administered anti-IL6 antibody significantly reduced lesion size compared to the vehicle control (p = 0.0054 on Day 15 and
p = 0.0005 on Day 22). There was no significant difference between the IL-6 antagonist and anti-VEGF positive control. The humanized antibody EBI-029 binds
Site II of human IL-6 with 200 pM affinity and potently blocks signaling of IL-6 and the IL-6/sIL-6Rα complex in cellular assays. A Fab fragment of EBI-029 was
thermally stable (Tm ~ 80°C), concentrated up to 20 mg/mL with no measurable aggregation, and has a vitreal clearance half-time of ~80 hours in rabbits.
Full-length IgG2 variants of EBI-029 with mutations in the Fc domain to ablate FcRn binding have been generated to further extend vitreal residence and reduce
systemic exposure.
• Humanized by CDR grafting and affinity matured
using AMP-RxTM platform to monovalent KD ~ 200 pM
Conclusions: Local IL-6 antagonism is efficacious in a rat model of choroidal neovascularization supporting the role of IL-6 in pathologic ocular angiogenesis.
A novel antibody against human IL-6, EBI-029, potently inhibits IL-6 cis- and trans-signaling and has excellent biophysical properties for IVT administration.
Together, this work supports the further development of EBI-029 as a therapy for diabetic macular edema either as a stand-alone drug or in combination with
VEGF blockade.
• Drug like properties are compatible with
requirements of IVT dosing
Site 2 blockade
Current Treatment Options
• EBI-029 is well expressed, thermally stable (Tm > 80°C
for Fab fragment), and soluble at 20 mg/mL in PBS,
pH 7.4
• EBI-029 is a humanized, affinity matured
antibody that binds Site 2 of IL-6 and
potently blocks the cis- and trans- signaling
pathways that drive pathologic signaling
• Epitope mapped to Site 2 of IL-6 by point mutant and
functional screening
Photocoagulation
Surgical procedure, damage to retina
Steroids
Increased intraocular pressure, risk of glaucoma and cataracts
Anti-VEGF
Significant refractory population, need for multiple re-injections
IL-6 is a pleiotropic cytokine with established roles in inflammation and angiogenesis. Excessive IL-6 signaling is implicated in several autoimmune diseases
with the IL-6 receptor antagonist Tocilizumab approved for treating rheumatoid arthritis. In the eye, vitreal IL-6 levels are significantly elevated in patients with
DME and positively correlate with disease severity (Yoshimura et al.). In animal models, intravitreal injection of IL-6 induces retinal leukostasis (Rojas et al.).
Additionally, ablation of IL-6 signaling by genetic knock-out or systemic treatment with anti-IL-6 receptor antibody significantly reduces angiogenesis and
macrophage infiltration in a murine laser induced choroidal neovascularization (CNV) model (Izumi-Nagai et al.).
Local IL-6 Blockade Reduces Choroidal Neovascularization
Vessel area (pixels)
Dual Role of IL-6 Signalling
*
*
*
Optimized Intravitreal Pharmacokinetics
[Antibody] (nM)
• Additional studies are underway to assess
the role of IL-6 in DME and characterize
EBI-029 activity and PK
[Antibody] (nM)
REFERENCES
• EBI-029 Fab fragment blocks both cis- and trans- IL-6
signaling due to Site 2 targeting; potency is
unchanged in the presence of sIL-6Rα
*
* p ≤ 0.005
Yau JWY et al. Global prevalence and major risk factor of
diabetic retinopathy. Diabetes Care (2012) 35:556-564
• Anti-IL-6Rα IgG clone B-R6 has decreased potency in
the presence of an excess of sIL-6Rα
Yoshimura et al. Comprehensive analysis of inflammatory
immune mediators in vitreoretinal diseases. PLoS One (2009)
4(12):e8158
Antagonism studies performed in HEK-BlueTM IL-6 reporter cells
(Invivogen) with 10 pM IL-6 and 50 nM sIL-6Rα
•
Laser induced CNV model performed in rats
•
3 µg of a polyclonal anti-rat-IL-6 antibody (R&D Systems AF506) administered
by IVT injection on Day 3 and 10 post laser significantly reduces
neovascularization compared to vehicle control as measured by in vivo
angiography
•
No significant difference in neovascularization between anti-IL6 treated group
and anti-VEGF positive control (R&D Systems polyclonal mAb AF564)
Comparison to Existing IL-6 Antagonists
Receptor blockade (Tocilizumab)
Site 1 blockade (Clinical antibodies)
DESIGNING OPTIMAL IL-6 BLOCKADE FOR THE EYE
IL-6 Signaling Mechanism
•
•
•
IL-6 signals through a hexameric complex
consisting of IL-6, IL-6Rα, and gp130 in a
2:2:2 ratio (Boulanger et al.)
Complex formation is driven by three
distinct binding sites on the IL-6 ligand:
Site 1, which binds IL-6Rα, Site 2, which
mediates binding of the IL-6/IL-6Rα
complex to gp130, and Site 3, which
drives association of the two IL-6/IL-6R
α/gp130 trimers
Both the membrane bound (cis-) and
soluble (trans-) forms of IL-6Rα are
capable of signaling
Both free IL-6 and the soluble IL-6/IL-6Ra
complex are upregulated in eye disease
and either can drive pathologic signaling
•
•
•
Existing IL-6 antagonists are designed for systemic administration
and have pharmacokinentic properties that are suboptimal for local,
ocular administration. In particular, they may require frequent
injections or have increased risk of systemic toxicity.
Goal – Develop a novel IL-6 antagonist with activity and
pharmacokinetics optimized for intravitreal (IVT) administration
Key criteria
- Potent blockade of free
IL-6 (cis- signaling) and
the IL-6/sIL-6Rα complex
(trans- signaling)
- Rapid systemic clearance
of molecules that escape
eye to minimize systemic
toxicity
- Slow vitreal clearance
following IVT administration
to support monthly or
greater frequency of dosing
- Excellent drug-like
properties compatible
with high concentration
IVT injection
Presentation #1062 /Poster #B0200, ARVO Annual Meeting, Session #: 158, Session Title: The Diabetic Retina: physiology and pharmacology, May 4, 2014 3:15 PM to 5:00 PM
Rojas M et al. Role of IL-6 in angiotensin II-induced retinal
vascular inflammation. Investigative Ophthalmology & Visual
Science (2010) 51(3):1709-1718
Izumi-Nagai K et al. Interleukin-6 receptor-mediated activation
of signal transducer and activator of transcription-3 (STAT3)
promotes choroidal neovascularization. Am J Pathol (2007)
170(6):2149-58
Boulanger MJ et al. Hexameric structure and assembly of the
interleukin-6/IL-6-receptor/gp130 complex. Science (2003) 300:
2101-2104.
Local IL-6 Antagonist Target Product Profile (TPP)
•
• EBI-029 has excellent stability and solubility
sufficient for high concentration IVT
delivery
• An engineered version of EBI-029 with
ablated FcRn binding has been developed
to reduce transcytotic clearance from the
eye and prevent systemic accumulation
Fractional IL-6 signaling
Limitation
Fractional IL-6 signaling
EBI-029 Potently Blocks Cis- and Trans- IL-6 Signaling
Therapeutic Approach
• Local blockade of IL-6 signaling is
efficacious in a rat model of laser-induced
choroidal neovascularization
• Existing IL-6 antagonists are designed for
systemic administration and may have
suboptimal pharmacokinetic properties for
local delivery, leading to frequent
administrations or risk of systemic toxicity
IL-6 IN DIABETIC MACULAR EDEMA
Background Biology: Diabetic macular edema (DME) is a serious, vision-threatening
complication arising in nearly 8% of diabetic patients (Yau JWY et al.). DME
pathology involves retinal leukostasis, breakdown of the retinal-blood barrier,
vascular leak, and neovascularization leading to swelling in the macula. While
several treatment options exist including photocoagulation, steroids, and VEGF
antagonists, these are each limited by toxicity or incomplete efficacy. Therefore,
there remains a significant unmet need for safe and effective therapies to be
administered either as stand alone drugs or in combination with VEGF blockade.
• IL-6 is significantly upregulated in the eyes
of patients with DME and likely contributes
to both the angiogenic and inflammatory
components of disease
Igawa T et al. Antibody recycling by engineered pH-dependent
antigen binding improves the duration of antigen
neutralization. Nature Biotechnology. (2010); 28(11):1203-1208
While several IL-6 antagonists exist in clinical development with one anti-IL-6Rα antibody, Tocilizumab, approved for treating RA, these
molecules are designed for systemic applications with suboptimal formats and epitopes for local ocular disease. In particular anti-IL-6Rα
antibodies are cleared quickly by receptor mediated internalization increasing the need for frequent administrations (Igawa et al.).
Additionally, both anti-receptor and anti-Site 1 antibodies can significantly increase the tissue concentration of IL-6 as they disrupt the
normal route of receptor mediated clearance (Nishimoto et al.). Lastly, both the anti-receptor and anti-Site 1 epitopes are sterically
occluded in preformed IL-6/sIL-6Rα complexes potentially reducing their efficacy against trans- signaling.
Presenting and corresponding author: Michael Schmidt, Eleven Biotherapeutics, mike.schmidt@elevenbio.com
Nishimoto N et al. Mechanisms and pathologic significances
in increase in serum interleukin-6 (IL-6) and soluble IL-6
receptor after administration of an anti–IL-6 receptor antibody,
tocilizumab, in patients with rheumatoid arthritis and
Castleman disease. Blood. (2008); 112(10):3959-3964.