Combined Antibodies Evusheld against the SARS-CoV-2 Omicron Variants BA.1.1 and BA.5: Immune Escape Mechanism from Molecular Simulation

[Effectiveness of tixagevimab/cilgavimab in reducing SARS-CoV-2 infections, hospitalizations and mortality in inmunocompromised patients]

INTRODUCTION

Inmunocompromised people have higher SARS-CoV-2 morbi-mortality and they are subsidiary to receive pre-exposure prophylaxis. The objective of this study is to evaluate the effectiveness of tixagevimab/cilgavimab (Evusheld) in preventing SARS-CoV-2 infections, hospitalizations and mortality in immunocompromised patients.

MATERIALS AND METHODS

119 immunocompromised people>18 years old eligible of receiving Evusheld were followed for 6 months. People with previous SARS-CoV-2 infection or incomplete vaccination regimen were exluded. A total of 19 people who received Evusheld were matched by propensity score, using a 1:1 ratio, with another 19 people who did not receive Evusheld. Sociodemographic, related to SARS-CoV-2 risk factors and related to immunosuppression variables were included. The dependent variables were infection, hospitalization, and mortality related to SARS-CoV-2. Statistical analyzes were performed using SPSS Statistics 19.0, STATA 11.0, and the R statistical package.

RESULTS

In total, 4 people in the Evusheld group and 11 in the control group had SARS-CoV-2 infection, showing an incidence rate of 3.87 and 13.62 per 100 person-months, respectively. The HR (Hazard Ratio) was 0.29 (95% CI=0.09-0.90) for SARS-CoV-2 infection, 0.37 (0.07-1.92) for SARS-CoV-2 hospitalization and, 0.23 (0.03-2.09) for SARS-CoV-2 mortality in the Evusheld group compared to control group.

CONCLUSIONS

This study demonstrates that Evusheld reduces the SARS-CoV-2 infections.

Understanding the Reversible Binding of a Multichain Protein-Protein Complex through Free-Energy Calculations

We demonstrate that the binding affinity of a multichain protein-protein complex, insulin dimer, can be accurately predicted using a streamlined route of standard binding free-energy calculations. We find that chains A and C, which do not interact directly during binding, stabilize the insulin monomer structures and reduce the binding affinity of the two monomers, therefore enabling their reversible association. Notably, we confirm that although classical methods can estimate the binding affinity of the insulin dimer, conventional molecular dynamics, enhanced sampling algorithms, and classical geometrical routes of binding free-energy calculations may not fully capture certain aspects of the role played by the noninteracting chains in the binding dynamics. Therefore, this study not only elucidates the role of noninteracting chains in the reversible binding of the insulin dimer but also offers a methodological guide for investigating the reversible binding of multichain protein-protein complexes utilizing streamlined free-energy calculations.

Prolonged Viral Shedding in Cancer Patients with Asymptomatic or Mild Omicron Infection: A Retrospective Study

Background

This study aimed to investigate the risk factors for persistent viral shedding in cancer patients after Omicron infection.

Methods

Patients with asymptomatic or mild Omicron infection (≥18 years) who were treated in a makeshift hospital in Shanghai were enrolled from 9 Apr to 11 May, 2022. Deidentified information of all patients were collected retrospectively. Logistic regression model was used to identify risk factors associated with prolonged duration of viral shedding (defined as the time from the day of first positive SARS-CoV-2 RNA test to the first day of two consecutive negative SARS-CoV-2 RNA tests).

Results

A total of 1442 Omicron-infected patients were enrolled, including 129 cancer patients and 1313 non-cancer patients. The baseline clinical characteristics of cancer and non-cancer patients were balanced by propensity score matching (1:4). Compared with non-cancer patients, a higher odds ratio ([OR] 1.84, 95% CI 1.24-2.76, P = 0.003) of lasting viral shedding for ≥7 days was found in cancer patients. Further subgroup analyses found that cancer patients were at higher risk for prolonged viral shedding in a subgroup of patients without hypertension (OR 1.89), diabetes (OR 1.80), or other chronic disease (OR 2.13), unvaccinated (OR 1.97), and asymptomatic (OR 2.36). In addition, 29 patients with active cancer and 19 patients with inactive cancer were identified. The median duration of viral shedding in the active cancer group was longer than that in the inactive cancer group (10 vs 6 days, P = 0.002). The risk of persistent viral shedding ≥7 days was also increased in the active cancer group (OR 5.33, 95% CI 1.49-21.51, P = 0.013).

Conclusion

Cancer disease is an independent risk factor for prolonged viral shedding in Omicron infected patients, especially in patients with active cancer.

Treatment-Emergent Cilgavimab Resistance Was Uncommon in Vaccinated Omicron BA.4/5 Outpatients

Mutations in the SARS-CoV-2 Spike glycoprotein can affect monoclonal antibody efficacy. Recent findings report the occurrence of resistant mutations in immunocompromised patients after tixagevimab/cilgavimab treatment. More recently, the Food and Drug Agency revoked the authorization for tixagevimab/cilgavimab, while this monoclonal antibody cocktail is currently recommended by the European Medical Agency. We retrospectively reviewed 22 immunocompetent patients at high risk for disease progression who received intramuscular tixagevimab/cilgavimab as early COVID-19 treatment and presented a prolonged high viral load. Complete SARS-CoV-2 genome sequences were obtained for a deep investigation of mutation frequencies in Spike protein before and during treatment. At seven days, only one patient showed evidence of treatment-emergent cilgavimab resistance. Quasispecies analysis revealed two different deletions on the Spike protein (S:del138-144 or S:del141-145) in combination with the resistance S:K444N mutation. The structural and dynamic impact of the two quasispecies was characterized by using molecular dynamics simulations, showing the conservation of the principal functional movements in the mutated systems and their capabilities to alter the structure and dynamics of the RBD, responsible for the interaction with the ACE2 human receptor. Our study underlines the importance of prompting an early virological investigation to prevent drug resistance or clinical failures in immunocompetent patients.

Tixagevimab/Cilgavimab as Pre-Exposure Prophylaxis against COVID-19 for Multiple Myeloma Patients: A Prospective Study in the Omicron Era

Background: tixagevimab/cilgavimab, distributed under the name "Evusheld", was the first available pre-exposure prophylaxis for COVID-19 other than vaccination. It received an EUA from the FDA after sufficient trial data showed efficacy in preventing SARS-CoV-2 infections and subsequent severe disease. Its potential benefits for high-risk immunocompromised patients generated a lot of interest. Individuals with multiple myeloma fall into this category, as they are characterized by attenuated immune responses and, in some cases, vaccines have limited efficacy. Methods: this single-center, prospective study included consecutive patients with multiple myeloma. All individuals were considered high-risk for COVID-19 due to their underlying disease. Baseline demographic and clinical characteristics, as well as data regarding COVID-19 infection and antibodies, were collected. Patients were administered two intramuscular 150 mg doses of Evusheld and were monitored during the follow-up period. Results: one hundred and eleven multiple myeloma patients were included in this analysis, with a median age of 64 years (range 58-69) and fifty-three were females (47.7%). Fourteen patients (12.6%) had a prior history of COVID-19 and all patients were vaccinated with either three or four doses of mRNA-based vaccines. An increase was observed in the median neutralizing-antibody levels before and after tixagevimab/cilgavimab administration, from 92.6% to 97.3%. The high levels were sustainable, with a median neutralizing-antibody level of 95.4% at 3 months post Evusheld administration. Overall, nine patients (8.1%) were diagnosed with COVID-19 during the follow-up period, at a median of 31 days. There were no SARS-CoV-2- infection-related hospitalizations or deaths. The monoclonal antibody combination was well tolerated, with no infusion-related reactions or major adverse events, and pain at the injection site only was reported by 33 patients (30%). Conclusions: tixagevimab/cilgavimab (Evusheld) seemed beneficial for patients with multiple myeloma, who presented high neutralizing-antibody levels and a low incidence of COVID-19 during the initial Omicron wave. No new safety concerns emerged. However, novel combinations of monoclonal antibodies against the new circulating variants of SARS-CoV-2 are deemed necessary in view of the emergence of immune tolerance.