Our findings suggest that the use of anakinra in patients with moderate hyperinflammation associated with severe SARS-CoV-2 pneumonia after previous failure of corticosteroid and/or tocilizumab therapy may be an alternative in the management of these patients, and may prevent deaths.
Immunosuppressive therapies are being used in patients with severe COVID-19 who develop hyperinflammatory state because of the pathogenic role of pro-inflammatory cytokines such as IL-1, IL-6 and tumor necrosis factor alpha.
Corticosteroid therapy has been used initially, and appears to reduce the mortality rate [19] [20]. Preliminary data from the RECOVERY trial showed that in severe COVID-19 pneumonia requiring oxygen or mechanical ventilation, moderate doses of dexamethasone resulted in lower 28-day mortality [21]. Tocilizumab, a humanized monoclonal antibody against IL-6, has been proposed to reduce the risk of intubation and/or death [22] [23] [24] [25] in patients with COVID-19 pneumonia associated with hyperinflammatory state, although it should be noted that the follow-up period in these previous studies was less than 28 days. In the present study, the 60-day mortality rate was similar in the group of patients who received corticosteroids and the group that received corticosteroids plus tocilizumab. However, the percentage of patients who required intubation was higher in the latter group, a finding probably related to the fact that those patients with worse quality of life and lower life expectancy for whom tocilizumab was ruled out as an option were also not considered candidates for ICU admission. These observations suggest that in patients with hyperinflammatory state who do not respond to corticosteroids, the addition of tocilizumab may not reduce mortality. This is consistent with phase III results from the COVACTA trial [26], which did not meet its primary endpoint of improved clinical status in hospitalized patients with severe COVID-19-associated pneumonia or its secondary endpoint of patient mortality at week 4. Together, these findings suggest the importance of determining the specific inflammatory profile in patients who are candidates for tocilizumab [27].
Anakinra is an IL-1 receptor antagonist that may be an alternative biologic for patients suffering from severe COVID-19 pneumonia and hyperinflammation who fail previous treatment with corticosteroids and/or tocilizumab. This drug may also have an additional beneficial effect on the prothrombotic state in these patients, since IL-1 blockade has been shown to reduce mortality rates in patients with acute myocardial infarction, as well as in patients with severe sepsis, liver dysfunction, and disseminated intravascular coagulation [28] [29] [30].
In the present study, 95% of the patients presented associated comorbidities, although without differences between treatment groups on admission in their CURB-65 or qSOFA scores. The predictive factors associated with higher mortality rate and worse prognosis were age, diabetes mellitus, ischemic heart disease, obesity, heart failure, hypertension, and kidney failure. Older age was the most important factor in patients with SARS-CoV-2 infection, and has been associated with the development of ARDS and subsequent death [31].
In the present study, the 30-day and 60-day mortality rate was lower in the group that received anakinra as rescue treatment after failure to respond to corticosteroids alone or with tocilizumab. This may have been a result of using an early treatment strategy with anakinra in patients who had not improved or who had worsened within 48 hours after receiving corticosteroid pulses and/or tocilizumab.
No differences were found in patients’ clinical course (death or ICU admission) at 60 days between patients with multimorbidity or patients older than 65 years treated with corticosteroids (group 1) and those who received corticosteroids and tocilizumab (group 2).
Regarding the 10 patients who received anakinra (group 3) because their clinical status did not improve or worsened despite treatment with corticosteroids and/or tocilizumab, their clinical course at 60 days (death or ICU admission) showed no association with previous treatment with corticosteroids alone or combined with tocilizumab. It is therefore possible that IL-1 blockade acted synergistically with corticosteroids or IL-6 blockade, and thus led to additional beneficial effects in controlling hyperinflammatory state.
The usefulness of anakinra therapy in patients with SARS-CoV-2 pneumonia who develop secondary hemophagocytic lymphohistiocytosis was recently reported [32]. This result together with the present findings suggests that anakinra could be administered instead of tocilizumab in patients with hyperinflammation associated with severe COVID-19 who have low serum IL-6 levels (<40) after failed corticosteroid therapy. The different cytokine profiles in these patients may determine their clinical response to the blockade of specific cytokines, a consideration we believe is important in designing future studies.
The likely beneficial effects of anakinra on the common pattern of coagulopathy observed in patients with COVID-19 were not associated with differences between groups in serum D-dimer levels before or after 3 days of treatment. Although IL-1 blockade has been associated with increased tissue factor expression, it is likely that other mechanisms derived from IL-1 blockade, such as reduced venous thromboinflammation and reduced platelet activation [33] [34] [35], may be beneficial in improving prothrombotic state in patients with severe SARS-CoV2 infection.
No differences were found in serum ferritin levels at 1 month between the three groups, suggesting that hyperinflammatory state was controlled to a similar degree in all patients regardless of their immunosuppressive treatment [36]. Although elevated ferritin levels have been considered a clinical factor associated with a poor prognosis in patients with cytokine storm [37], we observed no between-group differences in the association between serum ferritin levels and mortality – a finding probably related in part to the fact that the elevation in ferritin was moderate in all patients in the present cohort. Other laboratory factors associated with a worse prognosis, e.g. lymphopenia [38], were not associated with an increased mortality rate in any treatment group. The analysis of lymphocyte subpopulations showed that CD4 count was significantly lower on day 3 in the group treated with anakinra, although there were no significant differences between groups in CD8 count. Patients with severe respiratory failure associated with SARS-CoV-2 infection present CD4 depletion, so it is likely that IL-1 blockade contributes to an increase in circulating CD4 and thus helps to restore immune balance, with a better prognosis [39].
The dose of anakinra used in the present cohort was established based on pharmacokinetic criteria and was adjusted to body weight in an effort to minimize the risk of infection, given that our patients had previously received corticosteroids and/or tocilizumab. In one recently published study [40] the dose of anakinra associated with clinical improvement in patients with ARDS, hyperinflammation, and COVID-19 was higher (10 mg/kg/d); however, these patients had not been previously treated with corticosteroids and/or tocilizumab. This higher dose of anakinra was associated with a 24% rate of severe adverse effects and a 14% rate of infectious complications. In the present study, no patients had infectious complications, probably because of the lower dose of anakinra; this finding was also reported in a recent study [13] that used similar doses of anakinra.
The limitations of the present study are its retrospective observational design and the small sample size of the group that received anakinra. In addition, all the patients rescued with anakinra were male, a factor associated with greater severity, and this does not allow us to extrapolate our observations to women. In addition, we note that the sample size in group 3 (anakinra treatment) was small, and that a larger sample size would likely influence the significance level. However, the patients were recruited consecutively, and the treatment protocol was the same for all patients. In addition, patients in all groups had similar clinical severity indexes and similar age distributions, making them a more or less homogeneous sample.
In conclusion, the use of anakinra in patients with moderate hyperinflammation associated with severe COVID-19 pneumonia after previous failure of corticosteroid and/or tocilizumab therapy may be an alternative for the management of these patients, and may reduce mortality. However, randomized clinical trials are needed to confirm the possible benefits of this therapeutic strategy.