Prescription of Anti-Spike Monoclonal Antibodies in COVID-19 Patients with Resistant SARS-CoV-2 Variants in Italy

Considerations for the development of monoclonal antibodies to address new viral variants in COVID-19

INTRODUCTION

Monoclonal antibody (mAb) therapies proved safe and effective in preventing progression of COVID-19 to hospitalization, but most were eventually defeated by continued viral evolution. mAb combinations and those mAbs that were deliberatively selected to target conserved regions of the SARS-CoV-2 spike protein proved more resilient to viral escape variants as evident by longer clinical useful lives.

AREAS COVERED

We searched PubMed for literature covering the need, development, and use of mAb therapies for COVID-19. As much of humanity now has immunity to SARS-CoV-2, the population at most risk is that of immunocompromised individuals. Hence, there continues to be a need for mAb therapies for immunocompromised patients. However, mAb use in this population carries the risk for selecting mAb-resistant variants, which could pose a public health concern if they disseminate to the general population.

EXPERT OPINION

Going forward, structural knowledge of the interactions of Spike with its cellular receptor has identified several regions that may be good targets for future mAb therapeutics. A focus on designing variant-resistant mAbs together with cocktails that target several epitopes and the use of other variant mitigating strategies such as the concomitant use of small molecule antivirals and polyclonal preparations could extend the clinical usefulness of future preparations.

The efficacy of antivirals, corticosteroids, and monoclonal antibodies as acute COVID-19 treatments in reducing the incidence of long COVID: a systematic review and meta-analysis

BACKGROUND

Whether treatment during acute COVID-19 results in protective efficacy against long COVID incidence remains unclear.

OBJECTIVES

To assess the relationship between acute COVID-19 treatments of antivirals, corticosteroids, and monoclonal antibodies (mAbs) and long COVID incidence, and their effects in different populations and individual symptoms.

METHODS

A systematic review and meta-analysis.

DATA SOURCES

Searches were conducted up to January 29, 2024 in PubMed, Medline, Web of Science, and Embase.

STUDY ELIGIBILITY CRITERIA

Articles that reported long COVID incidence post-acute COVID with a follow-up of at least 30 days with no language restrictions.

PARTICIPANTS

Patients with a COVID-19 diagnosis history.

INTERVENTIONS

Patients treated with antivirals, corticosteroids or mAbs.

ASSESSMENT OF RISK OF BIAS

Quality assessment was based on the Newcastle-Ottawa scale, risk of bias in nonrandomized studies of interventions-I and Cochrane risk of bias tool.

METHODS OF DATA SYNTHESIS

Basic characteristics were documented for each study. Random forest model and meta-regression were used to evaluate the correlation between treatments and long COVID.

RESULTS

Our search identified 2363 records, 32 of which were included in the qualitative synthesis and 25 included into the meta-analysis. Effect size from 14 papers investigating acute COVID-19 antiviral treatment concluded its protective efficacy against long COVID (OR, 0.61; 95% CI, 0.48-0.79; p 0.0002); however, corticosteroid (OR, 1.57; 95% CI, 0.80-3.09; p 0.1913), and mAbs treatments (OR, 0.94; 95% CI, 0.56-1.56; p 0.8012) did not generate such effect. Subsequent subgroup analysis revealed that antivirals provided stronger protection in the aged, male, unvaccinated and nondiabetic populations. Furthermore, antivirals effectively reduced 8 out of the 22 analysed long COVID symptoms.

CONCLUSIONS

Our meta-analysis determined that antivirals reduced long COVID incidence across populations and should thus be recommended for acute COVID-19 treatment. There was no relationship between mAbs treatment and long COVID, but studies should be conducted to clarify acute COVID-19 corticosteroids' potential harmful effects on the post-acute phase of COVID-19.

COVID-19 therapeutics

SUMMARYSince the emergence of COVID-19 in 2020, an unprecedented range of therapeutic options has been studied and deployed. Healthcare providers have multiple treatment approaches to choose from, but efficacy of those approaches often remains controversial or compromised by viral evolution. Uncertainties still persist regarding the best therapies for high-risk patients, and the drug pipeline is suffering fatigue and shortage of funding. In this article, we review the antiviral activity, mechanism of action, pharmacokinetics, and safety of COVID-19 antiviral therapies. Additionally, we summarize the evidence from randomized controlled trials on efficacy and safety of the various COVID-19 antivirals and discuss unmet needs which should be addressed.

Sotrovimab: A Review of Its Efficacy against SARS-CoV-2 Variants

Among the anti-Spike monoclonal antibodies (mAbs), the S-309 derivative sotrovimab was the most successful in having the longest temporal window of clinical use, showing a high degree of resiliency to SARS-CoV-2 evolution interrupted only by the appearance of the BA.2.86* variant of interest (VOI). This success undoubtedly reflects rational selection to target a highly conserved epitope in coronavirus Spike proteins. We review here the efficacy of sotrovimab against different SARS-CoV-2 variants in outpatients and inpatients, discussing both randomized controlled trials and real-world evidence. Although it could not be anticipated at the time of its development and introduction, sotrovimab's use in immunocompromised individuals who harbor large populations of variant viruses created the conditions for its eventual demise, as antibody selection and viral evolution led to its eventual withdrawal due to inefficacy against later variant lineages. Despite this, based on observational and real-world data, some authorities have continued to promote the use of sotrovimab, but the lack of binding to newer variants strongly argues for the futility of continued use. The story of sotrovimab highlights the power of modern biomedical science to generate novel therapeutics while also providing a cautionary tale for the need to devise strategies to minimize the emergence of resistance to antibody-based therapeutics.

A Web Tool to Estimate Baseline Anti-Spike Monoclonal Antibody Efficacy Based on Regional Genomic Surveillance

Drug appropriateness is a pillar of modern evidence-based medicine, but the turnaround times of genomic sequencing are not compatible with the urgent need to deliver treatments against microorganisms. Massive worldwide genomic surveillance has created an unprecedented landscape for exploiting viral sequencing for therapeutic purposes. When it comes to therapeutic antiviral antibodies, using IC₅₀ against specific polymorphisms of the target antigen can be calculated in vitro, and a list of mutations leading to drug resistance (immune escape) can be compiled. The author encountered this type of knowledge (available from the Stanford University Coronavirus Antiviral Resistance Database,) in a publicly accessible repository of SARS-CoV-2 sequences. The author used a custom function of the CoV-Spectrum.org web portal to deliver up-to-date, regional prevalence estimates of baseline efficacy for each authorized anti-spike mAb across all co-circulating SARS-CoV-2 sublineages at a given time point. This publicly accessible tool can inform therapeutic choices that would otherwise be blind.

SARS-CoV-2 variants resistant to monoclonal antibodies in immunocompromised patients constitute a public health concern

COVID-19 in immunocompromised hosts has emerged as a difficult therapeutic management problem. Immunocompromised hosts mount weak responses to SARS-CoV-2 and manifest infection outcomes ranging from severe disease to persistent infection. Weakened immune systems mean greater viral loads and increased opportunities for viral evolution. Gupta, Konnova, et al. report the emergence of resistant SARS-CoV-2 variants in immunocompromised patients after monoclonal antibody (mAb) therapy. mAbs target only a single determinant in the viral Spike protein, which is a weakness of such therapy when treating a mutagenic and variable virus. Hence, the emergence of mAb resistance could have been anticipated, but its documentation is important because it has major public health implications, since such resistant variants have the potential to spread and escape vaccine immunity. For immunocompromised patients, these findings suggest the need for combination therapy with antiviral drugs and the use of polyclonal antibody preparations such as convalescent plasma.

Tixagevimab + cilgavimab against SARS-CoV-2: the preclinical and clinical development and real-world evidence

INTRODUCTION

Direct-acting SARS-CoV-2 antiviral monoclonal antibodies have been an integral part of therapeutic strategies against COVID-19 pandemic. The monoclonal strategy was jeopardized by the emergence of new variants and resistant strains, making many monoclonal antibodies quickly obsolete. Nevertheless, a possible strategy consists in the use of antibody cocktails and the development of the cilgavimab + tixagevimab in combination is placed in this context.

AREAS COVERED

In this review, we describe the development of the cilgavimab + tixagevimab cocktail, from pre-clinical to real-world evidence.

EXPERT OPINION

The pre-clinical and clinical development of cilgavimab + tixagevimab followed a similar path to that of the antibodies developed in the earlier stages of the pandemic. Both antibodies have been developed from convalescent plasma and have been shown to be effective in clinical trials in prophylaxis and in early therapy. This cocktail has found its position in therapy especially in immunocompromised subjects for whom vaccine prevention is not feasible. The cocktail strategy, together with a more stable pandemic situation, could ensure a certain longevity to the drug against resistance, especially when compared with that of other antibodies. Recently emerged Omicron sub-lineages have demonstrated the ability to escape this cocktail's activity and so the future of this treatment could be compromised.

A Clinical Update on SARS-CoV-2: Pathology and Development of Potential Inhibitors

SARS-CoV-2 (severe acute respiratory syndrome) is highly infectious and causes severe acute respiratory distress syndrome (SARD), immune suppression, and multi-organ failure. For SARS-CoV-2, only supportive treatment options are available, such as oxygen supportive therapy, ventilator support, antibiotics for secondary infections, mineral and fluid treatment, and a significant subset of repurposed effective drugs. Viral targeted inhibitors are the most suitable molecules, such as ACE2 (angiotensin-converting enzyme-2) and RBD (receptor-binding domain) protein-based inhibitors, inhibitors of host proteases, inhibitors of viral proteases 3CLpro (3C-like proteinase) and PLpro (papain-like protease), inhibitors of replicative enzymes, inhibitors of viral attachment of SARS-CoV-2 to the ACE2 receptor and TMPRSS2 (transmembrane serine proteinase 2), inhibitors of HR1 (Heptad Repeat 1)-HR2 (Heptad Repeat 2) interaction at the S2 protein of the coronavirus, etc. Targeting the cathepsin L proteinase, peptide analogues, monoclonal antibodies, and protein chimaeras as RBD inhibitors interferes with the spike protein's ability to fuse to the membrane. Targeting the cathepsin L proteinase, peptide analogues, monoclonal antibodies, and protein chimaeras as RBD inhibitors interferes with the spike protein's ability to fuse to the membrane. Even with the tremendous progress made, creating effective drugs remains difficult. To develop COVID-19 treatment alternatives, clinical studies are examining a variety of therapy categories, including antibodies, antivirals, cell-based therapy, repurposed diagnostic medicines, and more. In this article, we discuss recent clinical updates on SARS-CoV-2 infection, clinical characteristics, diagnosis, immunopathology, the new emergence of variant, SARS-CoV-2, various approaches to drug development and treatment options. The development of therapies has been complicated by the global occurrence of many SARS-CoV-2 mutations. Discussion of this manuscript will provide new insight into drug pathophysiology and drug development.

WHO Is Recommending against the Use of COVID-19 Convalescent Plasma in Immunocompromised Patients?

Since December 2019, SARS-CoV-2 is ravaging the globe, currently accounting for over 660 million infected people and more than 6 [...].

Effectiveness of Sotrovimab in the Omicron Storm Time: A Case Series

Neutralizing monoclonal antibodies (mAbs) for pre- and post-exposure prophylaxis of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) are largely used to prevent the progression of the disease by blocking viral attachment, host cell entry, and infectivity. Sotrovimab, like other available mAbs, has been developed against the receptor binding Domain of the Spike (S) glycoprotein of the virus. Nevertheless, the latest Omicron variant has shown marked mutations within the S gene, thus opening the question of the efficacy of these neutralizing molecules towards this novel variant. In the present observational study, we describe the effects of Sotrovimab in the treatment of 15 fully vaccinated patients, infected by SARS-CoV-2 Omicron sub-variants, who were selected on the basis of factors widely considered to affect a worse prognosis: immune suppression (n = 12) and/or chronic kidney disease (n = 5) with evidence of interstitial pneumonia in nine patients. The effectiveness of Sotrovimab in the treatment of severe cases of COVID-19 was demonstrated by the regression of symptoms (mean 5.7 days), no need of hospitalisation, improvement of general health conditions and viral clearance within 30 days in all patients. In conclusion, although loss or reduction of mAbs neutralizing activity against the Omicron variant have been described, Sotrovimab has clinically proven to be a safe and useful treatment for patients with high risk of progression to severe COVID-19 infected by Omicron sub-variants.

Home and Out-of-Hospital Therapy with COVID-19 Convalescent Plasma in Europe

COVID19 convalescent plasma (CCP) has proven an effective treatment for outpatients, and CCP collected from vaccinated donors is among the few effective therapeutic options for immunocompromised patients. Despite this, most countries are still relying over in-hospital compassionate usages outside clinical trials. Given the need for early treatment, home transfusions are expecially needed. We review here the state of the art for out-of-hospital CCP transfusions and discuss solutions to potential burocratic hurdles.

A Critical Analysis of the Use of Cilgavimab plus Tixagevimab Monoclonal Antibody Cocktail (Evusheld™) for COVID-19 Prophylaxis and Treatment

Evusheld® (tixagevimab + cilgavimab; AZD7442) was the first anti-Spike monoclonal antibody (mAb) cocktail designed not only for treatment but also with pre-exposure prophylaxis in mind. The immunoglobulins were engineered for prolonged half-life by modifying the Fc fragment, thus creating a long-acting antibody (LAAB). We review here preclinical development, baseline and treatment-emergent resistance, clinical efficacy from registration trials, and real-world post-marketing evidence. The combination was initially approved for pre-exposure prophylaxis at the time of the SARS-CoV-2 Delta VOC wave based on a trial conducted in unvaccinated subjects when the Alpha VOC was dominant. Another trial also conducted at the time of the Alpha VOC wave proved efficacy as early treatment in unvaccinated patients and led to authorization at the time of the BA.4/5 VOC wave. Tixagevimab was ineffective against any Omicron sublineage, so cilgavimab has so far been the ingredient which has made a difference. Antibody monotherapy has a high risk of selecting for immune escape variants in immunocompromised patients with high viral loads, which nowadays represent the main therapeutic indication for antibody therapies. Among Omicron sublineages, cilgavimab was ineffective against BA.1, recovered efficacy against BA.2 and BA.2.12.1, but lost efficacy again against BA.4/BA.5 and BA.2.75. Our analysis indicated that Evusheld® has been used during the Omicron VOC phase without robust clinical data of efficacy against this variant and suggested that several regulatory decisions regarding its use lacked consistency. There is an urgent need for new randomized controlled trials in vaccinated, immunocompromised subjects, using COVID-19 convalescent plasma as a control arm.

Monoclonal Antibodies for Pre- and Postexposure Prophylaxis of COVID-19: Review of the Literature

Monoclonal antibodies are laboratory-made proteins that mimic the immune system's ability to fight off harmful microorganisms, including viruses such as Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2). The US Food and Drug Administration (FDA) and the European Medical Agency (EMA) have already authorized monoclonal antibodies of anti-SARS-CoV-2 to treat mild to moderate CoronaVIrus Disease-2019 (COVID-19) in patients at risk of developing severe disease. More recently, monoclonal antibodies anti-SARS-CoV-2 have been authorized for primary and secondary prophylaxis in patients at high risk of severe disease for background comorbidity. Primary or pre-exposure prophylaxis prevents COVID-19 in unexposed people, whereas secondary or postexposure prophylaxis prevent COVID-19 in recently exposed people to individuals with laboratory-confirmed SARS-CoV-2. This review focuses briefly on therapeutic indications of currently available monoclonal antibodies for COVID-19 pre- and postexposure prophylaxis and on the efficacy of convalescent plasma.