The Molecular Mechanism of Shiga Toxin Stx2e Neutralization by a Single-domain Antibody Targeting the Cell Receptor-binding Domain

8025 Background: Relapsed/refractory (RR) multiple myeloma (MM), RRMM, remains as an incurable disease and has a 5-year survival rate of nearly 50%. To address the unmet medical need, an autologous CAR-T cell therapy was developed previously with a humanized single-domain antibody (sdAb) targeting BCMA as the antigen binding domain, 4-1BB and CD3ζ as cytoplasmic domain. Methods: An investigator-initiated clinical trial (IIT) was conducted in China to assess the safety and efficacy of the sdAb-based CAR-T. The trail was started in June 2018 and the last patient infused in June 2019. As of 1 February 2021, 34 were treated and followed up. The patients had received multiple lines of prior treatment (including bortezomib, lenalidomide, and others). Following a lymphodepleting regimen of cyclophosphamide (300-600 mg/m2, d-5, -4) and fludarabine (25-30 mg/m2, d-5 to d-3), patients were infused with 2.5-10.0 × 106 CAR+ cells/kg body weight. CAR-T was infused immediately after preparation and quality control performed in all patients except one, who was infused a 10.0 × 106 CAR+ cells/kg dose of frozen cells. Efficacy was assessed based on the IMWG criteria, toxicity was graded by CTCAE 4.02, and CRS grading was based on the grading system by CARTOX working group. Results: All 34 patients had the tumor burden of plasma cells in bone marrow, or M protein or free light chains (FLCs) in serum, 7 patients were accompanied with extramedullary diseases. The efficacy shows the best ORR is 88.2% (30/34), sCR rate is 55.9% (19/34). The mPFS was 12.1 months, several patients shows continuous sCR after 2 years. No obvious correlation between efficacy and dosage were found in three dose groups of 2.5×106 CAR+ cells/kg (6 pts), 5.0×106 CAR+ cells/kg (23 pts) or 10.0×106 CAR+ cells/kg (5 pts). The observed adverse events include thrombocytopenia (≥grade 3, 38.2%), neutropenia (≥grade 3, 44.1%), leukopenia (≥grade 3, 32.4%), lymphopeniPa (≥grade 3, 26.5%), and anemia (≥grade 3, 20.6%). CRS was monitored occurring in 29 patients (any grade, 85.3%, ≥grade 3, 2.9%). Conclusions: Our result demonstrates that the CART employing one humanized sdAb targeting BCMA is safe and efficacious for clinical application. The phase I clinical trial has been initiated in China for searching the RP2D using the cryopreserved CAR-T cells. Clinical trial information: NCT03661554.

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Allosteric Cross-Talk among Spike’s Receptor-Binding Domain Mutations of the SARS-CoV-2 South African Variant Triggers an Effective Hijacking of Human Cell Receptor

The Journal of Physical Chemistry Letters ◽

10.1021/acs.jpclett.1c01415 ◽

2021 ◽

pp. 5987-5993

Author(s):

Angelo Spinello ◽

Andrea Saltalamacchia ◽

Jure Borišek ◽

Alessandra Magistrato

Keyword(s):

South African ◽

Receptor Binding ◽

Cross Talk ◽

Human Cell ◽

Cell Receptor ◽

Binding Domain ◽

Receptor Binding Domain

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SARS-CoV-2 Prion-Like Domains in Spike Proteins Enables Higher Affinity to ACE2

10.20944/preprints202003.0422.v1 ◽

2020 ◽

Author(s):

George Tetz ◽

Victor Tetz

Keyword(s):

Receptor Binding ◽

Cell Receptor ◽

Binding Domain ◽

Spike Protein ◽

Striking Difference ◽

Receptor Binding Domain ◽

Viral Receptor ◽

Functional Roles ◽

Binding Domains ◽

Spike Proteins

Currently, the world is struggling with the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Prion-like domains are critical for virulence and the development of therapeutic targets; however, the prion-like domains in the SARS-CoV-2 proteome have not been analyzed. In this in silico study, using the PLAAC algorithm, we identified the presence of prion-like domains in SARS-CoV-2 spike protein. Compared with other viruses, a striking difference was observed in the distribution of prion-like domains in the spike, since SARS-CoV-2 was the only coronavirus with a prion-like domain found in the receptor-binding domain of the S1 region of the spike protein. The presence and unique distribution of prion-like domains in the SARS-CoV-2 receptor-binding domains of spike proteins is particularly interesting, since although SARS-CoV-2 and SARS-CoV S share the same host cell receptor, angiotensin-converting enzyme 2 (ACE2), SARS-CoV-2 demonstrates a 10- to 20-fold higher affinity for ACE2. Finally, we identified prion-like domains in the α1 helix of the ACE2 receptor that interacts with the viral receptor-binding domain of SARS-CoV-2. Taken together, the present findings indicate that the identified PrDs in the SARS-CoV-2 receptor-binding domain (RBD) and ACE2 region that interacts with RBD have important functional roles in viral adhesion and entry.

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Computational insights into differential interaction of mamalian ACE2 with the SARS-CoV-2 spike receptor binding domain

10.1101/2021.02.02.429327 ◽

2021 ◽

Author(s):

Cecylia S. Lupala ◽

Vikash Kumar ◽

Xiao-dong Su ◽

Chun Wu ◽

Haiguang Liu

Keyword(s):

Receptor Binding ◽

Cell Receptor ◽

Binding Domain ◽

Cell Entry ◽

Receptor Binding Domain ◽

Sequence Structure ◽

Angiotensin Converting Enzyme 2 ◽

Host Cell Receptor ◽

Comparison Results ◽

Horseshoe Bat

AbstractThe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causing agent of the COVID-19 pandemic, has spread globally. Angiotensin-converting enzyme 2 (ACE2) has been identified as the host cell receptor that binds to receptor-binding domain (RBD) of the SARS-COV-2 spike protein and mediates cell entry. Because the ACE2 proteins are widely available in mammals, it is important to investigate the interactions between the RBD and the ACE2 of other mammals. Here we analyzed the sequences of ACE2 proteins from 16 mammals and predicted the structures of ACE2-RBD complexes. Analyses on sequence, structure, and dynamics synergistically provide valuable insights into the interactions between ACE2 and RBD. The comparison results suggest that the ACE2 of bovine, cat and panda form strong binding with RBD, while in the cases of rat, least horseshoe bat, horse, pig, mouse and civet, the ACE2 proteins interact weakly with RBD.

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