Emergency Use of Tocilizumab in Moderate and Severe COVID-19 Patients over the Prevaccination Stage during the Pandemic in Mexico

Introduction COVID-19 has been associated with the overactivation of the immune system; interleukin-6 (IL-6) seems to have a key role, which made its moderation to be proposed as a therapeutic blank. Tocilizumab has been used as part of treatments to modulate the immune response to infections caused by COVID-19. Material and Methods. An observational, descriptive, retrospective, and transversal study was carried out in patients diagnosed with moderate-severe COVID-19 who were hospitalized in the 251 General Regional Hospital from March to December 2020. Results A review of 700 files corresponding to hospitalized patients was carried out, and a sample of 70 patients who met the inclusion criteria proposed for this protocol was obtained. Among the comorbidities associated with the disease, it was found that hypertensive patients have a higher mortality rate: 62% died and so did 59% of those who needed invasive respiratory support. As regards admission tests, statistical significance was found for the figures of leukocytes, neutrophils, glomerular filtration rate, and PCR. Conclusion The use of this drug benefits mainly young nonhypertensive patients with a moderate disease and preserved renal functions with no need for invasive respiratory support, regardless of other comorbidities.


Introduction
In December 2019, the World Health Organization received a report from Chinese authorities regarding a group of 27 pneumonia cases with unknown etiology in the city of Wuhan (Hubei province) [1,2].
As of November 9 th , 2022, at the global level, 630,387,858 cases have been verifed, while 6,583,163 deaths have been recorded. In America, 180,429, 028 cases have been confrmed, while in Mexico, the fgures are 5,517 cases per 100,000 inhabitants and 256.6 confrmed deaths per 100,000 [3]. Up to the date mentioned above, 7,113,429 confrmed cases and 344,384 deaths have been registered in the country. In the state of Mexico, there have been 703,712 verifed cases [4].
Several drugs have been put forward as candidates for the treatment of this disease. Among them, we fnd those that block the bond of the host cell by means of angiotensinconverting enzyme (ACE), the union with TMPRSS2, endocytosis, viral replication, and infammatory processes [5]. It is worth mentioning that none of the drugs mentioned above have been tried; however, they have been used as rescue treatments for this disease [6].
COVID-19 pneumonia has been associated with lung damage, severe immunosuppression, and lymphopenia. In this scenario, the presence of some immunological biomarkers in the prognosis of the disease has been assessed, as demonstrated in a prospective study, which reported a worse prognosis in patients with ANA autoantibodies, reinforcing the role of inappropriate immune regulation in this disease [7]. On the other hand, there are cases of autoimmune thrombocytopenia associated with COVID-19, which support the presence of alterations in immune regulation [8].
In Iraq, a cross-sectional study was performed on COVID-19 patients for the purpose of fnding out the correlation among routine hematological, immunological, and infammatory markers, as well as their relationship with the severity of the disease. In this study, the authors found out that the IL-6 count of lymphocytes and neutrophils represents major risk factors in the severity of this disease [9].
Since an increase in the levels of IL-6 has been described as a consequence of the overactivation of the immune system in COVID-19 patients, the use of a blocker for such interleukin was suggested in order to limit the infammatory process triggered by the virus [10][11][12].
Blocking IL-6 by means of an antibody against its receptor has proven to be efcacious in various autoimmune diseases. Moreover, the use of the recombinant monoclonal antibody receptor of antihuman IL-6, tocilizumab, is presently approved for rheumatic diseases such as rheumatoid arthritis and juvenile idiopathic arthritis [13,14].
Tere is limited information regarding the use of this drug in COVID-19 patients, mainly from retrospective studies with few patients. Also, there are limited data about the outcomes of using this drug in Latin America and Mexico. Te few existing trials are limited to critical disease conditions in specialized medical centers.
Te following study describes a retrospective analysis on the characteristics and outcomes of patients who received tocilizumab during the frst stage before the COVID-19 vaccination campaign started in Mexico, in a second-level hospital, as a rescue treatment for moderate to severe disease. Te purpose of this characterization was to assess the variables related to prognosis improvements and mortality diminution in Mexican patients.

Methodology
Tis is a single-center, observational, retrospective, and transversal study carried out at Hospital General Regional No. 251 (HGR 251) of the Mexican Social Security Institute (IMSS).
Te sample comprised patients older than 18 years of age with a diagnosis of moderate to severe COVID-19 who were hospitalized in the facilities mentioned above during the frst and second waves of COVID-19 before the vaccination campaign.
Te inclusion criteria considered patients who had previously received tocilizumab doses in the internal medicine hospitalization service according to the internal algorithms of IMSS [15], while the exclusion criteria screened patients with contraindications due to tocilizumab hypersensitivity, latent tuberculosis, a history of diverticulitis, and verifed bacterial infections associated.

Statistical Analysis.
Te results were recorded in a digital database. Qualitative values will be expressed as means with ranges and standard deviation, while qualitative, in percentage. Te Kolmogorov-Smirnov (KS) test was applied to defne normality. Parametric quantitative values were analyzed with a Student's T-test, whereas the nonparametric quantitative values were analyzed with Mann-Whitney U test. Finally, qualitative variables were analyzed by means of the chi-squared test. Statistical analyses were run using Statistical Software for Social Sciences (IBM SPSS Statistics for Windows, Version 22.0, Armonk, NY: IBM Corp).

Ethical Aspects.
Since the research proposal corresponds to a study with no risk and retrospective in nature, permission was asked to avoid using an informed consent letter in the understanding of the obligation of preserving the confdentiality of personal and medical data and also restating the commitment to only obtaining the information necessary for the present study, which will be used in the research protocol.
Te study was submitted to the local research committee for revision, and after meeting the ethical requirements for research, it was approved with the registration number R-2021-1503-049.

Results
A review of the fles of 700 patients admitted to Hospital General Regional 251 during the frst and second COVID-19 waves, before the beginning of the vaccination campaign, was carried out, and a sample of 70 patients was obtained. Te patients meet the inclusion criteria proposed for this protocol. Among the basal characteristics of the population, we have a mean age of 49 years, ranging from 23 to 78 years; men account for 58.6% of the sample. Te mean of the onset of symptomatology was 8.49 ± 6.91 days. Obesity, hypertension, and diabetes mellitus were found among the most prevalent comorbidities; other basal characteristics are displayed in Table 1.
In addition to the treatment with tocilizumab, the totality of patients received enoxaparin, 94.3% clarithromycin, and 70% steroids.
Among the comorbidities associated with the disease, it was found that hypertensive patients have a higher mortality rate; 62% of these patients died, and no other comorbidity was statistically signifcant for the outcome of patients who received the drug; other comorbidities and their related mortality are displayed in Table 2.
Furthermore, 59% of the patients who needed invasive respiratory support died; this implies a worse prognosis for patients who received the drug and were intubated.
As for the pharmacological treatment associated with tocilizumab use and hospital outcome, we did not fnd statistical signifcance for any of the drugs mentioned above.
It was noticed that at younger ages, there is a higher likelihood for survival, considering that the average age of the survivors was 47.6 years, as compared with 54.45 of those who died.
In relation to admission tests, statistical signifcance was found for leukocytes, neutrophils, glomerular fltration rate (GFR), and PCR. While there was a higher count of leukocytes and neutrophils, there was an increase in mortality.
Renal function deterioration, expressed as a diminution of GFR, is associated with a worse prognosis as compared with those who retain good renal function.
Higher levels of PCR were associated with higher mortality in patients who received the drug. Other admission tests and their related mortality are displayed in Table 3.

Discussion
Te COVID-19 pandemic produced an unprecedented situation for which there were neither defned strategies nor guidance to treat this disease. In this context, various drugs for its treatment appeared [5,16,17] previously existing treatments were utilized, some of them indicated for chronic conditions [18]; among the drugs used to restrict the infammatory process were found the antagonist of IL-6, also known as pleiotropic cytokine, produced by a large amount of hematopoietic and somatic cells, which are in charge of multiple biological activities [13,14].
Te receptor of IL-6 (IL-6R) has two forms: one joined to the receptor of the interleukin-6 membrane (mIL-6R) and another as a soluble receptor (sIL-6R). IL-6 joins mIL-6R to produce a complex that then joins the gp130 protein to induce intracellular dimerization and signaling of the kinase Janus pathway/transducers and activators of the transcription signal (JAK/STAT); moreover, the phosphatase SHP2 joins the phosphorylated gp130 and mediates the activation of the Ras-Raf-MAPK pathway [19,20].
sIL-6R may be generated via two diferent mechanisms, i.e., the proteolysis of the membrane receptor by the metalloproteinase ADAM17 and the transition of spliced mRNA. Trough this receptor, cells with the protein gp130 in their membrane may be activated by IL-6 even in the absence of its membrane receptor [20].
Te activation of the cells by means of sIL-6R represents the proinfammatory activity of this interleukin, which leads to the recruitment of mononuclear cells, the inhibition of both T lymphocyte apoptosis and the diferentiation of Tregulator lymphocytes, and the stimulation of endothelial cells for MPC1 production [20]. However, the activation of the membrane receptor implies the activation of the STAT3 pathway, which generates the proliferation of epithelial intestinal cells, inhibits apoptosis at the epithelial level, and also induces a hepatic response to infammatory processes [20].
Te blocking of IL-6 by means of an antibody against its receptor has proven to be efcacious in various autoimmune diseases [19]. Presently, tocilizumab is approved for use in rheumatic diseases such as rheumatoid arthritis and juvenile idiopathic arthritis [13,14].
Te use of this sort of drugs in the face of a scarcely studied situation has various implications, among which one fnds the following: (1) the risk of not administering a drug that may improve the health of a patient positive to SARS-  CoV2; (2) the adverse efects of using a nonapproved drug for this disease; and (3) the risk of harming patients with chronic pathologies who need constant administration of these drugs and did not fnd them due to their limited availability [18].
Te scarce information about the use of this drug in patients with COVID-19 mainly comes from retrospective studies with few patients such as a single-center retrospective study in Italy, which included patients hospitalized in an intensive care unit. A total of 65 patients who met the inclusion criteria were selected. Tese criteria considered PCRconfrmed disease and the hyperinfammation stage, defned as PCR over 100 mg/L, ferritin over 900 ng/mL, LDH over 220 U/L, compatible tomographic data, and PaO 2 /FiO 2 under 300. Patients were grouped to receive standard treatment, as compared with standard treatment plus tocilizumab 400 mg, in two doses, fnding a higher survival and lower intubation rate in patients who were given this drug [21].
Another single-center retrospective cohort study carried out in Cleveland Clinic intended to fnd out the outcome of patients treated with tocilizumab; the sample comprised 51 patients, out of which 55% received this drug. In the analysis, patients who were given this drug experienced clinical improvement in shorter time (8 v. 13 days), used fewer vasopressors, and required less invasive mechanical ventilation [22].
A randomized open and controlled study was carried out in the United Kingdom to assess the various possible treatments for COVID-19 in such country and included patients with saturation under 92% or with supplementary oxygen requirements, as well as evidence of systemic infammation, to randomize them in standard care compared with standard care plus tocilizumab. Among the fndings of this study, we fnd a higher likelihood of hospital admission at 28 days, 57% v. 50%, with a lower possibility to undergo advanced respiratory tract management or end up in death, 35% v. 42%. In this way, it is concluded that this drug is able to improve survival and other clinical outcomes as well [23].
Some retrospective studies have demonstrated no diminution for mortality or during respiratory support in patients with severe disease [21,22].
However, other studies, i.e., COVINTOC, an open-label, randomized, phase-3 trial that compared the use of tocilizumab supplied as a single infusion at 6 mg/kg v. standard care did not show any beneft [24].
A randomized, double-blind, placebo-controlled phase-3 trial evaluated the safety and efcacy of tocilizumab in hospitalized patients with COVID-19 pneumonia with no need for mechanical ventilation; the selection of patients focused on the inclusion of high-risk patients and the minority population, which comprises 56% of Hispanics or Latinos. Te authors conclude that for hospitalized patients with COVID-19 pneumonia who were not receiving mechanical ventilation, tocilizumab reduced the likelihood of progression, nevertheless it did not improve survival [25].
In Mexico, there are few studies on this drug. One of them was a prospective cohort study that included 99 patients with severe and critical COVID-19 for the purpose of assessing the efect of tocilizumab on hospital mortality in severe and critical COVID-19 patients in a third-level medical center. Te study found no diferences between groups and mortality and concluded that tocilizumab was not associated with decreased hospital mortality [26].
Furthermore, the role of timing in the administration of this drug has been studied in a retrospective, observational study that was carried out with the aim of evaluating the mortality and prognosis of diferent administration times of tocilizumab, and it was found that mortality was only reduced when the drug was administered at early infammatory stages (8 to 15 days of the symptoms) [27].
Some of the clinical characteristics associated with the outcomes after using tocilizumab in the present retrospective study are as follows: clinical response was favorable Advances in Virology in younger patients; age was not described in other retrospective studies as a critical factor for the outcome of the use of this drug; however, being hypertensive was associated with an increment in mortality, while the rest of the comorbidity characteristics did not have a statistically signifcant impact on the outcome of the patients. In like manner, vital signs at admission did not make a signifcant diference in the outcome. Patients with good renal functions were additionally beneftted by the use of tocilizumab as compared with those with deteriorated functions, still with no need for therapy to substitute renal functions.
Higher levels of C-reactive protein are associated with the worst outcome. Moreover, the vast majority of patients received other drugs in addition to tocilizumab, and this did not modify the end result; in any case, the need for invasive respiratory support was associated with higher mortality; as noticed in other trials, maybe the use of tocilizumab on patients with no need for mechanical ventilation is associated with the improvement of mortality rates.

Conclusion
We may conclude that the use of this drug mainly benefts young, nonhypertensive patients with a moderate disease, preserved renal functions, and no need for invasive mechanical ventilation, regardless of the rest of their comorbidities.
Among the limitations of the study, we have that it was carried out in a single center with a limited sample and no placebo comparison; plus, there was no analysis on invasive respiratory support. A study on a larger population is necessary for more efectively ascertaining the characteristics of the population for which this drug is useful.

Data Availability
Te data used to support the study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that they have no conficts of interest.