Elarekibep (PRS-060/AZD1402), a new class of inhaled Anticalin medicine targeting IL-4Ra for type 2 endotype asthma

Abstract

T2 endotype asthma is driven by IL-4 and IL-13 signaling via IL-4Ra, which is highly expressed on airway epithelium, airway smooth muscle and immunocytes in the respiratory mucosa, suggesting potential advantages of an inhalable antagonist. Lipocalin 1 (Lcn1), a 16kD protein abundant in human periciliary fluid, has a robust drug-like structure well-suited to protein engineering, but has never been used to make an inhaled "Anticalin" protein therapeutic. To re-engineer Lcn1 into an inhalable IL-4Ra antagonist and assess its pharmacodynamic/kinetic profile. Lcn1 was systematically modified by directed protein mutagenesis yielding a high affinity, slowly dissociating, long-acting full antagonist of IL-4Ra designated 'PRS-060' with properties analogous to dupilumab, competitively antagonizing IL-4Ra dependent cell proliferation, mucus induction and eotaxin expression in vitro. As PRS-060 displayed exquisite specificity for human IL-4Ra, with no cross-reactivity to rodents or higher primates, we created a new triple-humanized mouse model substituting hIL-4Ra, hIL-4, and hIL-13 at their correct syntenic murine loci to model clinical dosing. Inhaled PRS-060 strongly suppressed acute allergic inflammation indices in triple humanized mice with a duration of action longer than its bulk clearance suggesting it may act locally in the lung. Lcn1 can be re-engineered into the Anticalin antagonist PRS-060, exemplifying a new class of inhaled topical, long-acting therapeutic with potential to treat T2 endotype asthma.