Tocilizumab in addition to standard of care in the management of COVID-19: a meta-analysis of RCTs

Therapeutic Impact of Tocilizumab in the Setting of Severe COVID-19; an Updated and Comprehensive Review on Current Evidence

Introduction

The COVID-19 pandemic caused by SARS-CoV-2 has been the major health concern in 2019 globally. Considering the severity and phase of the disease, various pharmacotherapy schedules were proposed. Here, we set out to provide close-up insights on the clinical utility of Tocilizumab (TCZ), a biologic monoclonal antibody in this regard.

Methods

In this comprehensive review, various databases, including Scopus, PubMed Central, Medline, Embase, Google Scholar, and preprint publishers (med/bioRxiv) were searched until January 30, 2024, according to the keywords and search criteria.

Results

Besides the pros and cons, compelling evidence purported the safety and efficacy of TCZ and indicated that it exhibits great potential to reduce short-term and all-cause (28-30-day) mortality. TCZ significantly drops the adverse events if administered in the right time course (in the inflammatory phase) during critical/severe COVID-19 pneumonia. Despite contradictory results, the benefits of TCZ appear significant, especially in combination with add-on therapies, such as corticosteroids. Although the safety of TCZ is acceptable, solid data is lacking as to its benefits during pregnancy. There are limited data on TCZ combination therapies, such as hemoperfusion, intravenous immunoglobulin (IVIG), simple O2 therapy, vasopressor support, convalescent plasma therapy, and even in vaccinated patients and COVID-19 reinfection, especially in elderly persons. In addition, the impact of TCZ therapy on the long-lasting COVID-19 is unclear.

Conclusion

Personalized medicine based on individual characteristics and pertinent clinical conditions must be considered in the clinicians' decision-making policy. Finally, to mitigate the risk-to-benefit ratio of TCZ, a treatment algorithm, based on available literature and updated national institute of health (NIH) and Infectious Diseases Society of America (IDSA) guidelines, is also proposed.

Tocilizumab for the treatment of COVID-19

INTRODUCTION

Since the beginning of the COVID-19 pandemic, the repurposing of medicines has been pursued to find interventions effective in preventing fatal outcome of the disease. One of these drugs was tocilizumab, an interleukin-6 inhibiting monoclonal antibody, previously used to treat several immune-related disorders.

AREAS COVERED

In this article, we present the results of the initial observational studies and subsequent randomized clinical trials on the efficacy and safety of tocilizumab in the treatment of COVID-19. Despite conflicting results, possibly due to the heterogeneity of the studied populations, large studies have ultimately proven that preventing IL-6 from attaching to its receptors can effectively reverse the fatal course of the disease. We also discuss the meta-analyses, which mostly supported the validity of tocilizumab therapy. We show how tocilizumab found its place in the most important recommendations on COVID-19 treatment and obtained authorization from the major regulatory authorities.

EXPERT OPINION

The criteria for optimizing tocilizumab therapy in COVID-19 still need to be established. They are also important considering the existing risks of future zoonotic spillovers and epidemics that may trigger hyperinflammation that could be efficiently blocked. The experience gained with tocilizumab shall be perceived as preparedness for future challenges.

Should We Interfere with the Interleukin-6 Receptor During COVID-19: What Do We Know So Far?

Severe manifestations of COVID-19 consist of acute respiratory distress syndrome due to an initially local reaction leading to a systemic inflammatory response that results in hypoxia. Many therapeutic approaches have been attempted to reduce the clinical consequences of an excessive immune response to viral infection. To date, systemic corticosteroid therapy is still the most effective intervention. More recently, new hope has emerged with the use of interleukin (IL)-6 receptor inhibitors (tocilizumab and sarilumab). However, the great heterogeneity of the methodology and results of published studies obfuscate the true value of this treatment, leading to a confusing synthesis in recent meta-analyses, and the persistence of doubts in terms of patient groups and the appropriate time to treat. Moreover, their effects on the anti-infectious or pro-healing response are still poorly studied. This review aims to clarify the potential role of IL-6 receptor inhibitors in the treatment of severe forms of COVID-19.

Application of Machine Learning in Hospitalized Patients with Severe COVID-19 Treated with Tocilizumab

Among the IL-6 inhibitors, tocilizumab is the most widely used therapeutic option in patients with SARS-CoV-2-associated severe respiratory failure (SRF). The aim of our study was to provide evidence on predictors of poor outcome in patients with COVID-19 treated with tocilizumab, using machine learning (ML) techniques. We conducted a retrospective study, analyzing the clinical, laboratory and sociodemographic data of patients admitted for severe COVID-19 with SRF, treated with tocilizumab. The extreme gradient boost (XGB) method had the highest balanced accuracy (93.16%). The factors associated with a worse outcome of tocilizumab use in terms of mortality were: baseline situation at the start of tocilizumab treatment requiring invasive mechanical ventilation (IMV), elevated ferritin, lactate dehydrogenase (LDH) and glutamate-pyruvate transaminase (GPT), lymphopenia, and low PaFi [ratio between arterial oxygen pressure and inspired oxygen fraction (PaO₂/FiO₂)] values. The factors associated with a worse outcome of tocilizumab use in terms of hospital stay were: baseline situation at the start of tocilizumab treatment requiring IMV or supplemental oxygen, elevated levels of ferritin, glutamate-oxaloacetate transaminase (GOT), GPT, C-reactive protein (CRP), LDH, lymphopenia, and low PaFi values. In our study focused on patients with severe COVID-19 treated with tocilizumab, the factors that were weighted most strongly in predicting worse clinical outcome were baseline status at the start of tocilizumab treatment requiring IMV and hyperferritinemia.