A Review of Safety Outcomes from Clinical Trials of Baricitinib in Rheumatology, Dermatology and COVID-19

Baricitinib is an oral, selective inhibitor of Janus kinase (JAK)1/JAK2 that transiently and reversibly inhibits many proinflammatory cytokines. This mechanism is a key mediator in a number of chronic inflammatory diseases; accordingly, baricitinib has been studied and approved for the treatment of several rheumatological and dermatological disorders, as well as COVID-19. This narrative review summarises and discusses the safety profile of baricitinib across these diseases, with special focus on adverse events of special interest (AESI) for JAK inhibitors, using integrated safety data sets of clinical trial data, and puts findings into context with the underlying risk in the respective disease populations, using supporting literature. We show that rates of infection with baricitinib generally reflected the inherent risk of the disease populations being treated, with serious infections and herpes zoster being more frequent in rheumatic diseases than in dermatological disorders, and herpes simplex being reported particularly in atopic dermatitis. Similarly, rates of major adverse cardiovascular events (MACE), venous thromboembolism (VTE) and malignancies were generally within or below the ranges reported for the respective disease populations, thereby reflecting the underlying risk; these events were therefore more frequent in patients with rheumatic diseases than in those with dermatological disorders, the latter of whom generally had low absolute risk. AESI were usually more common in patients with risk factors specific for each event. When a population similar to that of ORAL Surveillance was considered, the incidence rate of MACE with baricitinib was numerically lower than that reported with tofacitinib and similar to that of tumour necrosis factor inhibitors. No safety concerns were observed in hospitalised patients with COVID-19 who received baricitinib for up to 14 days. Identifying the patterns and likelihoods of AEs that occur during treatment in large groups of patients with different diseases can help the physician and patient better contextualise the benefit-to-risk ratio for the individual patient. Plain Language Summary The oral selective inhibitor of Janus kinase (JAK)1/JAK2 baricitinib transiently and reversibly inhibits elements of the inflammatory pathway, which are key mechanisms for several chronic, inflammatory rheumatological and dermatological diseases but, as with all drugs, it can be associated with unwanted effects. This narrative review summarises adverse events of special interest (AESI) for baricitinib, considered as such either because of characteristics of patients with the disease being treated (rheumatological and dermatological disorders and COVID-19) or the mechanism of action of the drug. The risk of these events is considered in light of the inherent risk of each event in populations with the respective diseases. We show that serious infections and herpes zoster during baricitinib therapy were most common in patients with rheumatological disorders, and herpes simplex was reported particularly in patients with atopic dermatitis, likely because of disease-related risk factors. MACE, VTE and malignancies generally occurred in baricitinib-treated patients with a frequency within or below the ranges reported for the respective disease populations. Rates generally reflected the underlying risk of the disease populations, being higher in patients with rheumatological diseases than in those with dermatological disorders, and mostly occurring in patients with underlying risk factors for the AESI. No safety concerns were observed in hospitalised patients with COVID-19 who received baricitinib for up to 14 days. Characterising patterns and likelihoods of unwanted events that occur during treatment in large groups of patients with different diseases can help put the actual risk to an individual patient into perspective.

Automated summary

Baricitinib is an oral, selective inhibitor of Janus kinase (JAK)1/JAK2 that transiently and reversibly inhibits proinflammatory cytokines. It has been approved for the treatment of rheumatological, dermatological disorders, and COVID-19. The safety profile of baricitinib varies across these diseases, with rates of infection and adverse cardiovascular events generally reflecting the inherent risk in the respective disease populations. Adverse events of special interest were more common in patients with risk factors specific to each event. Short-term use of baricitinib in hospitalized patients with COVID-19 did not raise safety concerns.