On Jun. 16, 2021, Pfizer and The Academic Research Organization (ARO) from the Hospital Israelita Albert Einstein announced that the New England Journal of Medicine had published positive findings from the STOP-COVID study (NCT04469114) evaluating the efficacy and safety of oral Janus kinase (JAK) inhibitor tofacitinib in 289 hospitalized adult patients with COVID-19 pneumonia who were not on ventilation.

The trial was a research collaboration between Pfizer and the ARO from the Hospital Israelita Albert Einstein in Sao Paulo, Brazil, which was the trial coordinating center. It is important to note that tofacitinib has not been approved or authorized for use by any regulatory authority worldwide for the treatment of COVID-19 and tofacitinib should not be used in patients with an active serious infection.

The trial demonstrated a lower cumulative incidence of death or respiratory failure through day 28 – the primary outcome of the study – with tofacitinib (18.1%) compared to placebo (29.0%) (risk ratio 0.63; 95% confidence interval [CI], 0.41 to 0.97; p=0.04). Death from any cause through day 28 occurred in 2.8% of patients in the tofacitinib group and in 5.5% in the placebo group (hazard ratio 0.49; 95% CI, 0.15 to 1.63).

Serious adverse events occurred in 20 patients (14.1%) in the tofacitinib group and 17 (12.0%) in the placebo group. Among protocol-specified adverse events of special interest, deep vein thrombosis, acute myocardial infarction, ventricular tachycardia, and myocarditis occurred in one patient each in the tofacitinib group; hemorrhagic stroke and cardiogenic shock occurred in one patient each in the placebo group. The incidence of serious infection was 3.5% in the tofacitinib group and 4.2% in the placebo group.

The multi-center, randomized, double-blind, placebo-controlled trial included adult patients hospitalized with COVID-19 pneumonia receiving standard of care. Patients were randomized in a 1:1 ratio to receive either tofacitinib 10 mg twice daily plus standard of care or placebo twice daily plus standard of care for up to 14 days or until hospital discharge. Overall, 89.3% used glucocorticoids during hospitalization, predominantly dexamethasone.