Efficacy and safety of tocilizumab in hospitalized COVID-19 patients: A systematic review and meta-analysis

SARS-CoV-2 variant evasion of monoclonal antibodies based on in vitro studies

Monoclonal antibodies (mAbs) offer a treatment option for individuals with severe COVID-19 and are especially important in high-risk individuals where vaccination is not an option. Given the importance of understanding the evolution of resistance to mAbs by SARS-CoV-2, we reviewed the available in vitro neutralization data for mAbs against live variants and viral constructs containing spike mutations of interest. Unfortunately, evasion of mAb-induced protection is being reported with new SARS-CoV-2 variants. The magnitude of neutralization reduction varied greatly among mAb-variant pairs. For example, sotrovimab retained its neutralization capacity against Omicron BA.1 but showed reduced efficacy against BA.2, BA.4 and BA.5, and BA.2.12.1. At present, only bebtelovimab has been reported to retain its efficacy against all SARS-CoV-2 variants considered here. Resistance to mAb neutralization was dominated by the action of epitope single amino acid substitutions in the spike protein. Although not all observed epitope mutations result in increased mAb evasion, amino acid substitutions at non-epitope positions and combinations of mutations also contribute to evasion of neutralization. This Review highlights the implications for the rational design of viral genomic surveillance and factors to consider for the development of novel mAb therapies.

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.

Lack of Difference in Tocilizumab Efficacy in the Treatment of Severe COVID-19 Caused by Different SARS-CoV-2 Variants

Tocilizumab (TOC) is presumed to be an effective and safe treatment for severe COVID-19, but its usefulness has not been yet investigated for different SARS-CoV-2 variants. This study aimed to evaluate the influence of TOC on mortality in patients with severe COVID-19 caused by Delta and non-Delta SARS-CoV-2 variants. In a retrospective analysis, we compared the medical records of 78 and 224 patients with severe COVID-19 due to Delta and non-Delta variants, respectively. A total of 30 patients with Delta and 84 with non-Delta variants were treated with TOC in addition to standard therapy. There were no statistically significant differences in mortality rate when comparing Delta vs. non-Delta patients nor when comparing those treated with TOC vs. not treated with TOC in both variants. Using a logistic regression model, in the examined population as a whole, we found an increased (p < 0.05) risk of death as leukocyte and erythrocyte counts decreased and as procalcitonin increased. Increased procalcitonin was significant for mortality in the Delta group, while decreased IL-6, leukocytes, and platelets and increased fibrinogen and procalcitonin were significant in the non-Delta group. Tocilizumab efficacy in severe COVID-19 does not differ between Delta or non-Delta virus variants. The Delta variant of SARS-CoV-2 does not increase mortality when compared to other virus strains.

Tocilizumab fails survival benefit in severe COVID-19 – A retrospective cohort study

Objectives:

Anti-interleukin-6 monoclonal antibody, tocilizumab, has produced mixed results in clinical trials for effectiveness against coronavirus disease 2019 (COVID-19). We conducted a retrospective cohort study to compare outcomes at 28 days of a cohort of patients with severe COVID-19 treated with tocilizumab and standard care, with those receiving standard care only.

Materials and Methods:

In this record-based retrospective cohort study, patients hospitalised with COVID-19 were classified into non-severe and severe disease as per institutional protocol. One cohort received tocilizumab with standard care and the second cohort received only standard care. Few patients also received high-dose steroids as ‘pulse’ steroids on initial clinical deterioration. Data were collected for the treatment given including oxygen interface, steroids, antimicrobials, duration of hospital stay in survivors, requirement of mechanical ventilation, and day of intubation from symptom onset. The primary outcome was to compare the all-cause mortality between the two groups. The effect of pulse steroid therapy on all-cause mortality was studied in the secondary outcome.

Results:

There was statistically significant mortality in the tocilizumab cohort as compared to standard care alone (HR 2.43, 95% CI 1.54–3.89). The need for mechanical ventilation was more in the tocilizumab cohort (85% vs. 18%, P < 0.001). Tocilizumab cohort had a delay in the day of intubation by a mean of 2.29 days from the day of symptom onset (P < 0.05). Pulse steroid administration showed increased all-cause mortality (HR 1.94, 95% CI 1.18–3.20) and risk of mechanical ventilation.

Conclusion:

Tocilizumab cohort showed higher mortality and need for mechanical ventilation in our study which contrasts the result of a few previous trials. Our study warrants the need for future clinical trials on this subject to ensure better treatment strategies in upcoming COVID-19 waves.