ABSTRACT
Background: Multiple studies have been conducted to investigate Tocilizumab in patients with cOVID-19 pneumonitis. However, published reports show conflicting results, largely due to weak retrospective designs and heterogeneity in critical methodological issues. Methods: : This open-label trial was structured according to the Simon’s optimal two-stage design in order to clarify which patients could really benefit from anti-IL6 strategies and how a future randomized trial should be designed to provide reliable and unequivocal results. 46 patients received a single infusion of Tocilizumab. Inclusion criteria were: SARS-CoV2 infection diagnosed by rt-PCR, multifocal interstitial pneumonia, need of oxygen therapy (FiO2 50%) to maintain SO2 >93%, recent (within the last 24 hours) worsening of lung function. Clinical outcomes were established a priori to assess whether a patient responded to treatment. A low number of carefully chosen clinical and biological markers was measured in order to test their predictive values. Primary end point was early and sustained clinical response. Results: : Twenty-one (46%) patients fulfilled pre-defined response criteria. Lower levels of IL-6 at 24 hours after tocilizumab infusion (p=0.049) and higher baseline values of PaO2/FiO2 (p=0.008) predicted a favorable clinical response. Patients not improving at 72 hours were also non-responder at day 7. 11/25 of non-responder patients were intubated and 7 died. High levels of vWF were detected in all sera, with a tendency towards higher concentrations in the non-responder group. Conclusions: : Objective clinical response rate overcame the pre-defined threshold of 30%. Efficacy of tocilizumab to improve respiratory function in selected patients with severe COVID-19 pneumonitis warrants investigations in randomized trials. Trial registration: NCT 04315480