Preclinical Safety Profile of a Depleting Antibody against CRTh2 for Asthma: Well Tolerated Despite Unexpected CRTh2 Expression on Vascular Pericytes in the Central Nervous System and Gastric Mucosa.
CRTh2 is expressed on immune cells that drive asthma pathophysiology. Current treatment options for severe asthma are inadequate and therapeutic antibody-mediated depletion of CRTh2-expressing cells represents a promising new therapeutic strategy. Here we report for the first time that CRTh2 is not only expressed on immune cells, but also on microvasculature in the central nervous system (CNS) and gastric mucosa in humans. Microvascular expression of CRTh2 raises a safety concern because a therapeutic antiCRTh2 antibody with enhanced depletion capacity could lead to vascular damage. To evaluate this safety risk, we characterized microvascular expression in human and in transgenic mice expressing human CRTh2 protein (hCRTh2.BAC.Tg) and found that CRTh2 is not localized to microvascular endothelium that is directly exposed to circulating therapeutic antibody, but rather, to pericytes that in the CNS are shielded from direct circulatory exposure by the blood-brain barrier. Immunohistochemical visualization of an intravenously administered antiCRTh2 antibody in transgenic mice revealed localization to microvascular pericytes in the gastric mucosa but not in the CNS, suggesting the blood-brain barrier effectively limits pericyte exposure to circulating therapeutic antibody in the CNS. Repeated dosing with a depleting antiCRTh2 antibody in hCRTh2.BAC.Tg mice revealed linear pharmacokinetics and no drug-related adverse findings in any tissues, including the CNS and gastric mucosa, despite complete depletion of CRTh2 expressing circulating eosinophils and basophils. Collectively, these studies demonstrate that the likelihood of drug-related CNS or gastrointestinal toxicity in humans treated with a therapeutic depleting antiCRTh2 antibody is low despite pericyte expression of CRTh2 in these tissues.
Departments of Safety Assessment.
Kathila S
KS
Rajapaksa
Immunology.
Tao
T
Huang
Pathology.
Neeraj
N
Sharma
Departments of Safety Assessment.
Shannon
S
Liu
Pathology.
Margaret
M
Solon
Preclinical and Translational Pharmacokinetics.
Arthur
A
Reyes
Pathology.
Sarah
S
Paul
Antibody Engineering.
Angie
A
Yee
Pathology.
Janet
J
Tao
Pathology.
Sreedevi
S
Chalasani
Neuroscience.
Nga
N
Bien-Ly
Biomedical Imaging.
Kai
K
Barck
Biomedical Imaging.
Richard A D
RA
Carano
Biochemical and Cellular Pharmacology;
Jianyong
J
Wang
Pathology.
Linda
L
Rangell
OMNI Biomarker Development, Genentech Inc, South San Francisco, California, 94080.
Meire
M
Bremer
Departments of Safety Assessment.
Dimitry M
DM
Danilenko
Departments of Safety Assessment.
Paula
P
Katavolos
Antibody Engineering.
Isidro
I
Hotzel
Immunology Preclinical and Translational Pharmacokinetics.
Karin
K
Reif
Pathology caustin@gene.com.
Cary D
CD
Austin
D000818:Animals; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000633:toxicity; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000633:toxicity; D001249:Asthma / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000378:metabolism; D002199:Capillary Permeability; D002490:Central Nervous System / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D005753:Gastric Mucosa / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007275:Injections, Intravenous; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020286:Pericytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011982:Receptors, Prostaglandin / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D018570:Risk Assessment; D014018:Tissue Distribution
D018927:Anti-Asthmatic Agents; D000911:Antibodies, Monoclonal; D011971:Receptors, Immunologic; D011982:Receptors, Prostaglandin; C036293:prostaglandin D2 receptor
G-protein coupled; biological modeling; exposure assessment; gene expression/regulation; histopathology; methods; receptor; risk assessment; transgenic models