Inhalable neutralizing antibodies - promising approach to combating respiratory viral infections.

Respiratory syncytial virus (RSV) causes substantial morbidity and mortality in infants, the immunocompromised, and the elderly. RSV infects the airway epithelium via the apical membrane and almost exclusively sheds progeny virions back into the airway mucus (AM), making RSV difficult to target by systemically administered therapies. An inhalable "muco-trapping" variant of motavizumab (Mota-MT), a potent neutralizing mAb against RSV F is engineered. Mota-MT traps RSV in AM via polyvalent Fc-mucin bonds, reducing the fraction of fast-moving RSV particles in both fresh pediatric and adult AM by ≈20-30-fold in a Fc-glycan dependent manner, and facilitates clearance from the airways of mice within minutes. Intranasal dosing of Mota-MT eliminated viral load in cotton rats within 2 days. Daily nebulized delivery of Mota-MT to RSV-infected neonatal lambs, beginning 3 days after infection when viral load is at its maximum, led to a 10 000-fold and 100 000-fold reduction in viral load in bronchoalveolar lavage and lung tissues relative to placebo control, respectively. Mota-MT-treated lambs exhibited reduced bronchiolitis, neutrophil infiltration, and airway remodeling than lambs receiving placebo or intramuscular palivizumab. The findings underscore inhaled delivery of muco-trapping mAbs as a promising strategy for the treatment of RSV and other acute respiratory infections.

Inhaled "Muco-Trapping" Monoclonal Antibody Effectively Treats Established Respiratory Syncytial Virus (RSV) Infections.

Soluble angiotensin‐converting enzyme 2 (ACE2) can act as a decoy molecule that neutralizes severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) by blocking spike (S) proteins on virions from binding ACE2 on host cells. Based on structural insights of ACE2 and S proteins, we designed a “muco‐trapping” ACE2‐Fc conjugate, termed ACE2‐(G4S)6‐Fc, comprised of the extracellular segment of ACE2 (lacking the C‐terminal collectrin domain) that is linked to mucin‐binding IgG1‐Fc via an extended glycine‐serine flexible linker. ACE2‐(G4S)6‐Fc exhibits substantially greater binding affinity and neutralization potency than conventional full length ACE2‐Fc decoys or similar truncated ACE2‐Fc decoys without flexible linkers, possessing picomolar binding affinity and strong neutralization potency against pseudovirus and live virus. ACE2‐(G4S)6‐Fc effectively trapped fluorescent SARS‐CoV‐2 virus like particles in fresh human airway mucus and was stably nebulized using a commercial vibrating mesh nebulizer. Intranasal dosing of ACE2‐(G4S)6‐Fc in hamsters as late as 2 days postinfection provided a 10‐fold reduction in viral load in the nasal turbinate tissues by Day 4. These results strongly support further development of ACE2‐(G4S)6‐Fc as an inhaled immunotherapy for COVID‐19, as well as other emerging viruses that bind ACE2 for cellular entry.

Engineering a “muco‐trapping” ACE2‐immunoglobulin hybrid with picomolar affinity as an inhaled, pan‐variant immunotherapy for COVID‐19

Effective treatment and immunoprophylaxis of viral respiratory infections with neutralizing monoclonal antibodies (mAbs) require maintaining inhibitory concentrations of mAbs at the airway surface. While engineered mAbs with increased affinity to the neonatal Fc receptor (FcRn) are increasingly employed, little is known how increased affinity of Fc to FcRn influences basal-to-apical transepithelial transport (transcytosis) of mAbs across the airway epithelium. To investigate this, we utilized a model of well-differentiated human airway epithelium (WD-HAE) that exhibited robust FcRn expression, and measured the transepithelial transport of a mAb against SARS-CoV-2 Spike protein (CR3022) with either wildtype IgG 1 -Fc or Fc modified with YTE or LS mutations known to increase affinity for FcRn. Despite the marked differences in the affinity of these CR3022 variants for FcRn, we did not find substantial differences in basal-to-apical transport reflective of systemic dosing, or apical-to-basal transport reflective of inhaled dosing, compared to the transport of wildtype IgG 1 -Fc. These results suggest increasing FcRn affinity may only have limited influence over transcytosis rates of systemically dosed mAbs across the human airway epithelium over short time scales. Over longer time scales, the elevated circulating levels of mAbs with greater FcRn affinity, due to more effective FcRn-mediated recycling, may better resupply mAb into the respiratory tract, leading to more effective extended immunoprophylaxis. 

Impact of mAb-FcRn affinity on IgG transcytosis across human well-differentiated airway epithelium

https://doi.org/10.1016/j.jtbi.2022.111334

Antibody protection from SARS-CoV-2 respiratory tract exposure and infection

Rationale: Although COVID-19 is predominantly a respiratory tract infection, current antibody treatments are administered by systemic dosing. We hypothesize that inhaled delivery of a muco-trapping monoclonal antibody would provide a more effective and convenient treatment for COVID-19. Objective: We investigated the safety, tolerability, and pharmacokinetics of IN-006, a reformulation of regdanvimab, an approved intravenous treatment for COVID-19, for nebulized delivery by a handheld nebulizer. Methods: A Phase 1 study was conducted in healthy volunteers. Study staff and participants were blinded to treatment assignment, except for pharmacy staff preparing the study drug. The primary outcomes were safety and tolerability. Exploratory outcomes were pharmacokinetic measurements of IN-006 in nasal fluid and serum. Results: Twenty-three participants were enrolled and randomized across two single dose and one multiple dose cohorts. There were no serious adverse events (SAEs). All enrolled participants completed the study without treatment interruption or discontinuation. All treatment-emergent adverse events were transient, non-dose dependent, and were graded mild to moderate in severity. Nebulization was well tolerated and completed in a mean of 6 minutes in the high dose group. Mean nasal fluid concentrations of IN-006 in the multiple dose cohort were 921 microgram/gram of nasal fluid at 30 minutes after dosing and 5.4 microgram/gram at 22 hours. Mean serum levels in the multiple dose cohort peaked at 0.55 microgram/mL at 3 days after the final dose. Conclusions IN-006 was well-tolerated and achieved concentrations in the respiratory tract orders of magnitude above its inhibitory concentration. These data support further clinical development of IN-006.

A randomized, double-blind, Phase 1 study of IN-006, an inhaled antibody treatment for COVID-19

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A randomized, double-blind, Phase 1 study of IN-006, an inhaled antibody treatment for COVID-19