Engineering ACE2 decoy receptors to combat viral escapability.

Decoy receptor proteins that trick viruses to bind to them should be resistant to viral escape because viruses that require entry receptors cannot help but bind decoy receptors. Angiotensin-converting enzyme 2 (ACE2) is the major receptor for coronavirus cell entry. Recombinant soluble ACE2 was previously developed as a biologic against acute respiratory distress syndrome (ARDS) and verified to be safe in clinical studies. The emergence of COVID-19 reignited interest in soluble ACE2 as a potential broad-spectrum decoy receptor against coronaviruses. In this review, we summarize recent developments in preclinical studies using various high-affinity mutagenesis and Fc fusion approaches to achieve therapeutic efficacy of recombinant ACE2 decoy receptor against coronaviruses. We also highlight the relevance of stimulating effector immune cells through Fc-receptor engagement and the potential of using liquid aerosol delivery of ACE2 decoy receptors for defense against ACE2-utilizing coronaviruses.

An engineered ACE2 decoy neutralizes the SARS-CoV-2 Omicron variant and confers protection against infection in vivo.

The Omicron (B.1.1.529) SARS-CoV-2 variant contains an unusually high number of mutations in the spike protein, raising concerns of escape from vaccines, convalescent serum, and therapeutic drugs. Here, we analyzed the degree to which Omicron pseudo-virus evades neutralization by serum or therapeutic antibodies. Serum samples obtained 3 months after two doses of BNT162b2 vaccination exhibited 18-fold lower neutralization titers against Omicron than parental virus. Convalescent serum samples from individuals infected with the Alpha and Delta variants allowed similar frequencies of Omicron breakthrough infections. Domain-wise analysis using chimeric spike proteins revealed that this efficient evasion was primarily achieved by mutations clustered in the receptor binding domain but that multiple mutations in the N-terminal domain contributed as well. Omicron escaped a therapeutic cocktail of imdevimab and casirivimab, whereas sotrovimab, which targets a conserved region to avoid viral mutation, remains effective. Angiotensin-converting enzyme 2 (ACE2) decoys are another virus-neutralizing drug modality that are free, at least in theory, from complete escape. Deep mutational analysis demonstrated that an engineered ACE2 molecule prevented escape for each single-residue mutation in the receptor binding domain, similar to immunized serum. Engineered ACE2 neutralized Omicron comparably to the Wuhan strain and also showed a therapeutic effect against Omicron infection in hamsters and human ACE2 transgenic mice. Similar to previous SARS-CoV-2 variants, some sarbecoviruses showed high sensitivity against engineered ACE2, confirming the therapeutic value against diverse variants, including those that are yet to emerge.

Engineered ACE2 receptor therapy overcomes mutational escape of SARS-CoV-2.

SARS-CoV-2 has mutated during the global pandemic leading to viral adaptation to medications and vaccinations. Here we describe an engineered human virus receptor, ACE2, by mutagenesis and screening for binding to the receptor binding domain (RBD). Three cycles of random mutagenesis and cell sorting achieved sub-nanomolar affinity to RBD. Our structural data show that the enhanced affinity comes from better hydrophobic packing and hydrogen-bonding geometry at the interface. Additional disulfide mutations caused the fixing of a closed ACE2 conformation to avoid off-target effects of protease activity, and also improved structural stability. Our engineered ACE2 neutralized SARS-CoV-2 at a 100-fold lower concentration than wild type; we also report that no escape mutants emerged in the co-incubation after 15 passages. Therapeutic administration of engineered ACE2 protected hamsters from SARS-CoV-2 infection, decreased lung virus titers and pathology. Our results provide evidence of a therapeutic potential of engineered ACE2.

Angiographic and Clinical Outcomes After Stent-less Coronary Intervention Using Rotational Atherectomy and Drug-Coated Balloon in Patients with De Novo Lesions.

OBJECTIVES: We investigated angiographic and clinical outcomes in patients with de novo lesions undergoing rotational atherectomy (RA) followed by drug-coated balloon (DCB) dilation (RA/DCB). BACKGROUND: Implantation of drug-eluting stent (DES) has been a mainstay of the interventional treatment of coronary artery disease (CAD); however, there still remain several DES-unsuitable clinical/lesion conditions. Nowadays DCB for de novo lesions has attracted more attention, and RA, which tends not to cause major dissection but to debulk intima, might be one of suitable pre-treatments before DCB. METHODS AND RESULTS: Thirty patients (34 lesions) undergoing RA/DCB for de novo lesions were enrolled. Clinical/lesion background included severe calcification, calcified nodule, inlet/outlet of aneurysm, ostial lesion, severe thrombocytopenia, bleeding tendency, and/or sequelae of Kawasaki disease. The largest burr size used was 1.83 ±â€¯0.23 mm, and the mean DCB diameter was 2.71 ±â€¯0.47 mm. Angiographic success was obtained in 94% of the lesions. No acute closure but 1 no reflow occurred. Repeat angiography (mean, 6.6 months after procedure) was performed for 19 lesions. Frequency of binary restenosis was 21.1%, and late lumen loss was 0.34 ±â€¯0.30 mm. During a mean follow-up period of 13.1 months, 6 deaths (2 sudden deaths, 1 cardiac death, 3 non-cardiac deaths), 2 strokes, and 2 target lesion revascularizations were observed. CONCLUSIONS: Stent-less PCI using RA/DCB might be an alternative revascularization therapy for CAD patients complicated with DES-unsuitable conditions.