“ <i>Nomen Omen</i> : The Myth of God Janus”

The Latins believed that a person's name could be indicative of the destiny, a notion encapsulated in the phrase “nomen omen.” This idea has endured over the centuries and remains a familiar expression in modern Italian. This paper playfully explores whether the name Janus—as found in Janus kinase inhibitors—was a foreshadowing of the characteristics and destiny of this drug class. Janus (Latin: Ianus) is the god of beginnings and transitions. He presides over doorways, gates, endings, and passages, including the shift from war to peace. The month of January (Ianuarius) is named after him, symbolizing a propitious start to the new year. Like many Roman deities, Janus had several epithets that highlight both his importance within the pantheon and the deep reverence for Romans. These included Divum Deus (“God of the Gods”) and Divum Pater (“Father of the Gods”) [1]. Due to his unique physical appearance, he was known as Bifrons (“two-faced”), having two faces joined at the back of his head, covered by hair (Figure 1). This duality granted him complete vision of time, his older face looking into the past, and his younger face gazing into the future [1]. Turning to the drug class: Janus kinases (JAKs) are a family of protein tyrosine kinases responsible for intracellular signal transduction. They were first discovered in 1989 by Wilks et al. Interestingly, their significance was not initially recognized. In fact, the original name was a somewhat not epic and dismissive acronym of “Just Another Kinase” [2]. It wasn't until 2 years later that the name was changed to the current Janus kinase. The name was inspired by the fact that these kinases appeared to contain two kinase-like domains, much like the two faces of the god Janus [3]. More than 30 years after this renaming, JAK inhibitors have become highly valued in dermatology and almost as cherished by dermatologists as Janus was by the ancient Romans. Striking parallels can be drawn between Janus and JAK inhibitors, extending far beyond the structural resemblance of their dual domains. Beginnings: JAK inhibitors have ushered in a new era in the treatment of several dermatological diseases that had previously seen unsatisfactory outcomes. Notable examples include: baricitinib (a JAK1/JAK2 inhibitor) and ritlecitinib (a JAK3/TEC inhibitor) approved for moderate-to-severe alopecia areata [4-6], ruxolitinib (JAK1/JAK2 inhibitor) approved for non-segmental vitiligo [7] and delgocitinib (a pan-JAK inhibitor) approved for chronic hand eczema [8]. Transitions: Atopic dermatitis (AD) is a chronic inflammatory skin condition that transitions over time from an acute phase—dominated by Th2 and Th22 responses—to a chronic phase characterized by the simultaneous activation of Th1, Th2, and Th17 immune pathways [9]. To date, three JAK inhibitors have been approved for moderate-to-severe AD: baricitinib, upadacitinib (selective JAK1 inhibitor), and abrocitinib (selective JAK1 inhibitor) [10]. These drugs modulate cytokine expression from both the Th2 and Th1 axes, making them capable of addressing different stages of AD [9]. In light of these parallels, it is fair to say that JAK inhibitors share more than just a name with the god Janus. The phrase “nomen omen” indeed feels appropriate. Janus could see the future—something we cannot. But perhaps his younger face is gazing upon a future where new JAK inhibitors will be developed, and even more patients will benefit from this evolving class of medications. The author has drafted the manuscript and critically reviewed its content autonomously. I wish to express my sincere gratitude to Prof. Maria Stella Mercurio, whose expertise in Latin literature greatly enriched this work through her invaluable suggestions and insights. The author has nothing to report. The author has no affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Data derived from public domain resources.